This document discusses the physiological changes that occur during pregnancy and how they impact anesthesia practice. It notes that pregnancy results in increased blood volume, cardiac output, respiratory rate and oxygen consumption to support the growing fetus. Regional and general anesthesia can impact the mother's cardiovascular and respiratory physiology, with risks of supine hypotension, hypoxemia and decreased uterine blood flow. Careful anesthetic management is needed to support both mother and fetus simultaneously during pregnancy and delivery.
Physiological Changes in Pregnancy and Its Anaesthetic Implications.Mohtasib Madaoo
This document summarizes the physiological changes in pregnancy and their implications for anesthesia. It discusses how pregnancy causes increased blood volume, cardiac output, oxygen consumption and acidity levels. These changes can cause issues like supine hypotension syndrome when the mother lies on her back. The document also covers respiratory, coagulation, gastrointestinal and central nervous system changes in pregnancy and how they impact drug dosages and anesthesia techniques. Special considerations are discussed for intubation, regional anesthesia and placental drug transport.
Cerebral physiology and effects of anaesthetic agentsRicha Kumar
The document discusses cerebral physiology and the effects of anesthetic agents. It covers topics such as:
- Anatomy of the cerebral circulation including the circle of Willis.
- Regulation of cerebral blood flow including chemical, myogenic, and neurogenic factors.
- Effects of increased intracranial pressure on cerebral perfusion.
- How different anesthetic agents like barbiturates, propofol, etomidate, narcotics, benzodiazepines, ketamine, and volatile anesthetics affect cerebral blood flow and cerebral metabolic rate.
The document discusses neurophysiology and factors controlling cerebral blood flow (CBF). Some key points:
- The brain has high metabolic needs but no oxygen storage, so it relies on continuous CBF. CBF parallels metabolic activity and averages 50 ml/100g/min.
- CBF is controlled by cerebral perfusion pressure (CPP), which depends on mean arterial pressure and intracranial pressure. Autoregulation normally keeps CBF constant over a wide range of pressures.
- Important factors influencing CBF include carbon dioxide, which causes vasodilation; oxygen; hematocrit; temperature; and anesthetic agents, many of which are cerebral vasodilators. Barbiturates
The document discusses various paediatric breathing circuits used in anaesthesia. It describes the key components and classifications of breathing circuits. The most commonly used circuits include the Mapleson A (Magill) system, which is best for spontaneous breathing but requires high fresh gas flows. The Mapleson D and Bain circuits are efferent reservoir systems that work efficiently for controlled ventilation. The Ayre's T-piece is a simple no-valve circuit designed for paediatric use. The document provides details on the construction, functioning and advantages of these different breathing circuit designs.
Caudal anesthesia involves injecting local anesthetic into the caudal canal of the sacrum to provide pain relief below the umbilicus. It can be used alone or with general anesthesia for surgeries involving the perineum, anus, rectum, or lower extremities. The technique involves identifying the sacral hiatus and inserting a needle, with ultrasound or fluoroscopy guidance available. Potential complications include dural puncture, nerve injury, and local anesthetic toxicity. The level of pain relief varies significantly among patients.
This document provides an outline and overview of key topics in obstetric anesthesia. It discusses the physiological changes that occur during pregnancy and how they impact anesthesia care. Specific areas covered include analgesia and anesthesia techniques for labor, cesarean delivery, and high-risk obstetric emergencies. Fetal monitoring and considerations for providing anesthesia for non-obstetric surgeries during pregnancy are also summarized. The document aims to educate anesthetists on understanding pregnancy physiology and its implications for safe anesthesia care during labor, delivery, and other procedures.
This document provides an overview of anesthesia considerations for laparoscopic surgeries. It discusses the history of laparoscopy, physiological effects of pneumoperitoneum including on the cardiovascular, respiratory, central nervous and renal systems. It also outlines respiratory complications like subcutaneous emphysema, pneumothorax, gas embolism and their treatment. The effects of patient positioning and conduct of anesthesia are summarized.
This document discusses pregnancy and surgery, specifically addressing whether they can safely mix. It notes that around 0.75-2% of pregnancies involve surgery. The most common surgeries are appendectomy, cholecystectomy, adnexal disease procedures, and trauma procedures. It reviews important physiologic changes in pregnancy and rates of complications from surgery. It discusses fetal hazards, principles of teratology, and implications for anesthetizing pregnant patients. It provides FDA categories and reviews effects of specific anesthetic agents. The document emphasizes using minimal effective doses of historically safe drugs and avoiding maternal hypotension, hypoxia, and hypercarbia.
Physiological Changes in Pregnancy and Its Anaesthetic Implications.Mohtasib Madaoo
This document summarizes the physiological changes in pregnancy and their implications for anesthesia. It discusses how pregnancy causes increased blood volume, cardiac output, oxygen consumption and acidity levels. These changes can cause issues like supine hypotension syndrome when the mother lies on her back. The document also covers respiratory, coagulation, gastrointestinal and central nervous system changes in pregnancy and how they impact drug dosages and anesthesia techniques. Special considerations are discussed for intubation, regional anesthesia and placental drug transport.
Cerebral physiology and effects of anaesthetic agentsRicha Kumar
The document discusses cerebral physiology and the effects of anesthetic agents. It covers topics such as:
- Anatomy of the cerebral circulation including the circle of Willis.
- Regulation of cerebral blood flow including chemical, myogenic, and neurogenic factors.
- Effects of increased intracranial pressure on cerebral perfusion.
- How different anesthetic agents like barbiturates, propofol, etomidate, narcotics, benzodiazepines, ketamine, and volatile anesthetics affect cerebral blood flow and cerebral metabolic rate.
The document discusses neurophysiology and factors controlling cerebral blood flow (CBF). Some key points:
- The brain has high metabolic needs but no oxygen storage, so it relies on continuous CBF. CBF parallels metabolic activity and averages 50 ml/100g/min.
- CBF is controlled by cerebral perfusion pressure (CPP), which depends on mean arterial pressure and intracranial pressure. Autoregulation normally keeps CBF constant over a wide range of pressures.
- Important factors influencing CBF include carbon dioxide, which causes vasodilation; oxygen; hematocrit; temperature; and anesthetic agents, many of which are cerebral vasodilators. Barbiturates
The document discusses various paediatric breathing circuits used in anaesthesia. It describes the key components and classifications of breathing circuits. The most commonly used circuits include the Mapleson A (Magill) system, which is best for spontaneous breathing but requires high fresh gas flows. The Mapleson D and Bain circuits are efferent reservoir systems that work efficiently for controlled ventilation. The Ayre's T-piece is a simple no-valve circuit designed for paediatric use. The document provides details on the construction, functioning and advantages of these different breathing circuit designs.
Caudal anesthesia involves injecting local anesthetic into the caudal canal of the sacrum to provide pain relief below the umbilicus. It can be used alone or with general anesthesia for surgeries involving the perineum, anus, rectum, or lower extremities. The technique involves identifying the sacral hiatus and inserting a needle, with ultrasound or fluoroscopy guidance available. Potential complications include dural puncture, nerve injury, and local anesthetic toxicity. The level of pain relief varies significantly among patients.
This document provides an outline and overview of key topics in obstetric anesthesia. It discusses the physiological changes that occur during pregnancy and how they impact anesthesia care. Specific areas covered include analgesia and anesthesia techniques for labor, cesarean delivery, and high-risk obstetric emergencies. Fetal monitoring and considerations for providing anesthesia for non-obstetric surgeries during pregnancy are also summarized. The document aims to educate anesthetists on understanding pregnancy physiology and its implications for safe anesthesia care during labor, delivery, and other procedures.
This document provides an overview of anesthesia considerations for laparoscopic surgeries. It discusses the history of laparoscopy, physiological effects of pneumoperitoneum including on the cardiovascular, respiratory, central nervous and renal systems. It also outlines respiratory complications like subcutaneous emphysema, pneumothorax, gas embolism and their treatment. The effects of patient positioning and conduct of anesthesia are summarized.
This document discusses pregnancy and surgery, specifically addressing whether they can safely mix. It notes that around 0.75-2% of pregnancies involve surgery. The most common surgeries are appendectomy, cholecystectomy, adnexal disease procedures, and trauma procedures. It reviews important physiologic changes in pregnancy and rates of complications from surgery. It discusses fetal hazards, principles of teratology, and implications for anesthetizing pregnant patients. It provides FDA categories and reviews effects of specific anesthetic agents. The document emphasizes using minimal effective doses of historically safe drugs and avoiding maternal hypotension, hypoxia, and hypercarbia.
This document provides information about epidural anaesthesia. It discusses the history and development of epidural techniques. It then describes the anatomy of the spinal cord, meninges, epidural space and sacral canal. It explains the mechanism of action of epidural anaesthesia and factors affecting drug distribution and elimination. Finally, it outlines the physiological effects of epidural anaesthesia on the cardiovascular, respiratory, gastrointestinal, genitourinary and neuroendocrine systems.
This document discusses low-flow and minimal-flow anesthesia techniques. It begins by defining low-flow as a fresh gas flow of 1 L/min and minimal-flow as 0.5 L/min. Rebreathing systems allow reuse of exhaled gases after removal of carbon dioxide. Using these techniques can reduce costs by 55-75% and minimize environmental pollution from volatile anesthetic gases. Proper monitoring and maintenance of breathing gas conditions is important for patient safety when using low fresh gas flows.
Pregnancy induced hypertension includes gestational hypertension, preeclampsia, chronic hypertension, and chronic hypertension with superimposed preeclampsia. Preeclampsia is a multisystem disorder caused by abnormal placentation leading to placental hypoxia and endothelial damage. Management involves maternal and fetal monitoring, antihypertensive treatment for severe hypertension, magnesium sulfate for seizure prophylaxis, and delivery once the fetus is mature. Anesthetic management is crucial and involves careful consideration of neuraxial versus general anesthesia depending on the severity of the preeclampsia and other maternal factors.
Cardiomyopathies are diseases of the heart muscle that cause it to be structurally and functionally abnormal without other known causes like coronary artery disease. There are several types including dilated, hypertrophic, restrictive, arrhythmogenic right ventricular, and Takotsubo cardiomyopathy. Anesthesia management aims to minimize negative inotropic effects, maintain appropriate preload and afterload, and prevent hypotension, arrhythmias, and tachycardia. Goals depend on the type of cardiomyopathy and whether systolic or diastolic dysfunction predominates. Close monitoring is important due to potential hemodynamic instability from anesthesia and surgery.
Advances in the field of labour analgesia have tread a long journey from the days of ether and chloroform in 1847 to the present day practice of comprehensive programme of labour pain management using evidence-based medicine. Newer advances include introduction of newer techniques like combined spinal epidurals, low-dose epidurals facilitating ambulation, pharmacological advances like introduction of remifentanil for patient-controlled intravenous analgesia, introduction of newer local anaesthetics and adjuvants like ropivacaine, levobupivacaine, sufentanil, clonidine and neostigmine, use of inhalational agents like sevoflourane for patient-controlled inhalational analgesia using special vaporizers, all have revolutionized the practice of pain management in labouring parturients.
Physiological changes in pregnancy and uteroplacental blood flowomar143
Physiological changes in pregnancy result in increased blood volume, cardiac output, and oxygen demand. The fetus receives oxygenated blood through the low-resistance placental circulation. Fetal blood circulation is characterized by shunts that direct blood away from the lungs. Uteroplacental blood flow is vital to fetal oxygen delivery and depends on perfusion pressure and vascular resistance. Monitoring of uteroplacental blood flow provides insight into fetal wellbeing.
This document discusses strategies for optimizing preoxygenation prior to endotracheal intubation. It notes that conventional preoxygenation techniques provide safe intubation for most ED patients but that a subset may still desaturate. To safely intubate this higher risk group, the document recommends optimizing preoxygenation through techniques like non-invasive ventilation, apneic oxygenation through nasal cannula, positioning patients in a head-up position, and breaking the sequence of rapid sequence intubation administration. The goal is to prevent deoxygenation and extend the safe apneic period for patients undergoing endotracheal intubation.
The document discusses monitored anesthesia care (MAC), which involves administering drugs to provide anxiolytic, hypnotic, amnestic, and analgesic effects without depressing consciousness below a certain level. It provides guidelines on drug selection and dosing for MAC, including opioids like fentanyl and remifentanil, benzodiazepines like midazolam, propofol, ketamine, and dexmedetomidine. It also discusses factors that can lead to patient agitation during MAC and principles of drug administration via continuous infusion or patient-controlled methods.
The document discusses obstetric emergencies including massive obstetric hemorrhage, antepartum hemorrhage from placenta previa or abruption, uterine rupture, and postpartum hemorrhage. It provides definitions, risk factors, diagnostic criteria, management guidelines, and anesthetic considerations for each of these conditions. Prevention and treatment involve careful monitoring, IV access, blood products, oxytocic medications, and timely delivery when indicated to stabilize both mother and fetus.
Regional anesthesia such as spinal or epidural anesthesia is preferred over general anesthesia for cesarean sections due to lower risks for both mother and baby. Spinal anesthesia provides rapid onset but a finite duration, while epidural anesthesia allows for gradual onset and better control of sensory levels via a catheter. Both techniques require careful management of hypotension through fluid administration and vasopressors. Neuraxial opioids can enhance analgesia without negatively impacting the neonate. The goals are to provide adequate anesthesia and analgesia for surgery and postoperatively while maximizing safety for mother and baby.
This document provides information on interscalene brachial plexus blocks, including indications, contraindications, anatomy, techniques, complications, and references. It describes Winnie's anterior approach using landmarks to identify the interscalene groove for injection, as well as a posterior approach. Areas of blockade, continuous techniques, and use of nerve stimulation are also summarized. Supraclavicular blockade as an alternative is outlined with similar details.
Anaesthetic management of ruptured ectopic pregnancy by Arowojolu BoluwajiArowojolu Samuel
anaesthetic management of a patient with ruptured ectopic pregnancy. helping anaesthetist to know what to do in emergency anaesthesia. this is an emergency case. salpingectomy. arowojolu boluwaji
The document discusses the history and current practices of pain management during childbirth. It notes that historically, childbirth pain was seen as divine punishment. Non-pharmacological techniques like acupuncture and hypnosis were used. Queen Victoria popularized using chloroform for pain relief in the 1800s. Now, over 90% of women receive some form of analgesia, mainly neuraxial techniques like epidurals that are considered very safe when administered properly. The document provides details on various analgesic options and their risks and benefits.
This document discusses low flow anaesthesia. It defines low flow as 500-1000 ml/min of fresh gas flow. The document outlines the technical requirements for safely conducting low flow anaesthesia, including monitors for inspired oxygen, end tidal CO2 and anaesthetic concentrations. It describes the initiation, maintenance and emergence phases of low flow anaesthesia, emphasizing achieving and maintaining an appropriate anaesthetic depth. The document discusses advantages like reduced cost and pollution compared to higher fresh gas flows.
This document discusses various methods for monitoring the depth of anesthesia. It describes clinical techniques such as assessing autonomic responses and muscle movement. It also discusses pharmacological principles like minimum alveolar concentration for different anesthetic responses. Methods for monitoring brain electrical activity are outlined, including spontaneous EEG, compressed spectral analysis, bispectral index, and entropy monitors. Brain electrical activity monitors provide quantitative measures of anesthetic effect but can be influenced by other physiological factors. Overall, the document provides an overview of traditional and advanced techniques for assessing depth of anesthesia.
Elderly patients represent the fastest growing population globally. They experience many age-related physiological changes that increase surgical risk. Preoperative evaluation and optimization is important to identify risks like cardiovascular disease and pulmonary issues. Anesthesia in the elderly requires lower doses of induction agents and opioids due to pharmacokinetic changes. Regional anesthesia may provide benefits over general anesthesia. Close postoperative monitoring is needed due to risks of complications like delirium, cognitive dysfunction, hypotension, and hypothermia.
This document discusses Minimum Alveolar Concentration (MAC) and related concepts:
- MAC is defined as the minimum alveolar concentration of an inhaled anesthetic needed to prevent movement in 50% of patients during surgery. It allows comparison of anesthetic potency.
- Meyer-Overton hypothesis links anesthetic potency to lipid solubility. Exceptions to this rule exist.
- MAC derivatives measure concentrations needed for other clinical endpoints like unconsciousness or amnesia.
- Many physiological, pharmacological, and pathological factors can increase or decrease an individual's MAC. Precise anesthetic dosing requires accounting for these factors.
Double lumen tubes were developed in the 1950s-60s to enable lung isolation during thoracic surgery. The Carlens and Bryce-Smith tubes were some of the earliest designs, featuring curves and cuffs to isolate the left or right mainstem bronchus. Modern tubes like the Robertshaw are widely used and come in varying sizes from 26-41 French. Placement requires careful advancement and confirmation via auscultation, cuff inflation, and bronchoscopy to avoid malposition and injury. Double lumen tubes allow selective ventilation and treatment of each lung but require replacement with a single tube after surgery.
The document summarizes the major physiological changes that occur during pregnancy across multiple body systems. Hormonal changes including increased progesterone, estrogen, prolactin, and cortisol levels help prepare the body for pregnancy. The pancreas produces higher insulin levels to regulate increased blood sugar levels and fuel metabolism. The uterus grows substantially larger to accommodate the fetus, and other organs like the cervix, vagina, blood vessels, and respiratory system also undergo changes. Weight gain during pregnancy of 11-16 kilograms is distributed between increased fluid, tissues, the placenta and developing baby. Most systems return to their pre-pregnancy state after delivery.
Physiological changes during pregnancy can be extensive. The uterus grows dramatically in size and the cervix softens. The breasts enlarge and darken. Throughout pregnancy, the body retains more fluid and blood volume increases. Respiration increases to support higher oxygen needs. The heart works harder pumping more blood. The kidneys and liver increase in size. Many hormonal changes prepare the body for childbirth and nurturing a baby.
This document provides information about epidural anaesthesia. It discusses the history and development of epidural techniques. It then describes the anatomy of the spinal cord, meninges, epidural space and sacral canal. It explains the mechanism of action of epidural anaesthesia and factors affecting drug distribution and elimination. Finally, it outlines the physiological effects of epidural anaesthesia on the cardiovascular, respiratory, gastrointestinal, genitourinary and neuroendocrine systems.
This document discusses low-flow and minimal-flow anesthesia techniques. It begins by defining low-flow as a fresh gas flow of 1 L/min and minimal-flow as 0.5 L/min. Rebreathing systems allow reuse of exhaled gases after removal of carbon dioxide. Using these techniques can reduce costs by 55-75% and minimize environmental pollution from volatile anesthetic gases. Proper monitoring and maintenance of breathing gas conditions is important for patient safety when using low fresh gas flows.
Pregnancy induced hypertension includes gestational hypertension, preeclampsia, chronic hypertension, and chronic hypertension with superimposed preeclampsia. Preeclampsia is a multisystem disorder caused by abnormal placentation leading to placental hypoxia and endothelial damage. Management involves maternal and fetal monitoring, antihypertensive treatment for severe hypertension, magnesium sulfate for seizure prophylaxis, and delivery once the fetus is mature. Anesthetic management is crucial and involves careful consideration of neuraxial versus general anesthesia depending on the severity of the preeclampsia and other maternal factors.
Cardiomyopathies are diseases of the heart muscle that cause it to be structurally and functionally abnormal without other known causes like coronary artery disease. There are several types including dilated, hypertrophic, restrictive, arrhythmogenic right ventricular, and Takotsubo cardiomyopathy. Anesthesia management aims to minimize negative inotropic effects, maintain appropriate preload and afterload, and prevent hypotension, arrhythmias, and tachycardia. Goals depend on the type of cardiomyopathy and whether systolic or diastolic dysfunction predominates. Close monitoring is important due to potential hemodynamic instability from anesthesia and surgery.
Advances in the field of labour analgesia have tread a long journey from the days of ether and chloroform in 1847 to the present day practice of comprehensive programme of labour pain management using evidence-based medicine. Newer advances include introduction of newer techniques like combined spinal epidurals, low-dose epidurals facilitating ambulation, pharmacological advances like introduction of remifentanil for patient-controlled intravenous analgesia, introduction of newer local anaesthetics and adjuvants like ropivacaine, levobupivacaine, sufentanil, clonidine and neostigmine, use of inhalational agents like sevoflourane for patient-controlled inhalational analgesia using special vaporizers, all have revolutionized the practice of pain management in labouring parturients.
Physiological changes in pregnancy and uteroplacental blood flowomar143
Physiological changes in pregnancy result in increased blood volume, cardiac output, and oxygen demand. The fetus receives oxygenated blood through the low-resistance placental circulation. Fetal blood circulation is characterized by shunts that direct blood away from the lungs. Uteroplacental blood flow is vital to fetal oxygen delivery and depends on perfusion pressure and vascular resistance. Monitoring of uteroplacental blood flow provides insight into fetal wellbeing.
This document discusses strategies for optimizing preoxygenation prior to endotracheal intubation. It notes that conventional preoxygenation techniques provide safe intubation for most ED patients but that a subset may still desaturate. To safely intubate this higher risk group, the document recommends optimizing preoxygenation through techniques like non-invasive ventilation, apneic oxygenation through nasal cannula, positioning patients in a head-up position, and breaking the sequence of rapid sequence intubation administration. The goal is to prevent deoxygenation and extend the safe apneic period for patients undergoing endotracheal intubation.
The document discusses monitored anesthesia care (MAC), which involves administering drugs to provide anxiolytic, hypnotic, amnestic, and analgesic effects without depressing consciousness below a certain level. It provides guidelines on drug selection and dosing for MAC, including opioids like fentanyl and remifentanil, benzodiazepines like midazolam, propofol, ketamine, and dexmedetomidine. It also discusses factors that can lead to patient agitation during MAC and principles of drug administration via continuous infusion or patient-controlled methods.
The document discusses obstetric emergencies including massive obstetric hemorrhage, antepartum hemorrhage from placenta previa or abruption, uterine rupture, and postpartum hemorrhage. It provides definitions, risk factors, diagnostic criteria, management guidelines, and anesthetic considerations for each of these conditions. Prevention and treatment involve careful monitoring, IV access, blood products, oxytocic medications, and timely delivery when indicated to stabilize both mother and fetus.
Regional anesthesia such as spinal or epidural anesthesia is preferred over general anesthesia for cesarean sections due to lower risks for both mother and baby. Spinal anesthesia provides rapid onset but a finite duration, while epidural anesthesia allows for gradual onset and better control of sensory levels via a catheter. Both techniques require careful management of hypotension through fluid administration and vasopressors. Neuraxial opioids can enhance analgesia without negatively impacting the neonate. The goals are to provide adequate anesthesia and analgesia for surgery and postoperatively while maximizing safety for mother and baby.
This document provides information on interscalene brachial plexus blocks, including indications, contraindications, anatomy, techniques, complications, and references. It describes Winnie's anterior approach using landmarks to identify the interscalene groove for injection, as well as a posterior approach. Areas of blockade, continuous techniques, and use of nerve stimulation are also summarized. Supraclavicular blockade as an alternative is outlined with similar details.
Anaesthetic management of ruptured ectopic pregnancy by Arowojolu BoluwajiArowojolu Samuel
anaesthetic management of a patient with ruptured ectopic pregnancy. helping anaesthetist to know what to do in emergency anaesthesia. this is an emergency case. salpingectomy. arowojolu boluwaji
The document discusses the history and current practices of pain management during childbirth. It notes that historically, childbirth pain was seen as divine punishment. Non-pharmacological techniques like acupuncture and hypnosis were used. Queen Victoria popularized using chloroform for pain relief in the 1800s. Now, over 90% of women receive some form of analgesia, mainly neuraxial techniques like epidurals that are considered very safe when administered properly. The document provides details on various analgesic options and their risks and benefits.
This document discusses low flow anaesthesia. It defines low flow as 500-1000 ml/min of fresh gas flow. The document outlines the technical requirements for safely conducting low flow anaesthesia, including monitors for inspired oxygen, end tidal CO2 and anaesthetic concentrations. It describes the initiation, maintenance and emergence phases of low flow anaesthesia, emphasizing achieving and maintaining an appropriate anaesthetic depth. The document discusses advantages like reduced cost and pollution compared to higher fresh gas flows.
This document discusses various methods for monitoring the depth of anesthesia. It describes clinical techniques such as assessing autonomic responses and muscle movement. It also discusses pharmacological principles like minimum alveolar concentration for different anesthetic responses. Methods for monitoring brain electrical activity are outlined, including spontaneous EEG, compressed spectral analysis, bispectral index, and entropy monitors. Brain electrical activity monitors provide quantitative measures of anesthetic effect but can be influenced by other physiological factors. Overall, the document provides an overview of traditional and advanced techniques for assessing depth of anesthesia.
Elderly patients represent the fastest growing population globally. They experience many age-related physiological changes that increase surgical risk. Preoperative evaluation and optimization is important to identify risks like cardiovascular disease and pulmonary issues. Anesthesia in the elderly requires lower doses of induction agents and opioids due to pharmacokinetic changes. Regional anesthesia may provide benefits over general anesthesia. Close postoperative monitoring is needed due to risks of complications like delirium, cognitive dysfunction, hypotension, and hypothermia.
This document discusses Minimum Alveolar Concentration (MAC) and related concepts:
- MAC is defined as the minimum alveolar concentration of an inhaled anesthetic needed to prevent movement in 50% of patients during surgery. It allows comparison of anesthetic potency.
- Meyer-Overton hypothesis links anesthetic potency to lipid solubility. Exceptions to this rule exist.
- MAC derivatives measure concentrations needed for other clinical endpoints like unconsciousness or amnesia.
- Many physiological, pharmacological, and pathological factors can increase or decrease an individual's MAC. Precise anesthetic dosing requires accounting for these factors.
Double lumen tubes were developed in the 1950s-60s to enable lung isolation during thoracic surgery. The Carlens and Bryce-Smith tubes were some of the earliest designs, featuring curves and cuffs to isolate the left or right mainstem bronchus. Modern tubes like the Robertshaw are widely used and come in varying sizes from 26-41 French. Placement requires careful advancement and confirmation via auscultation, cuff inflation, and bronchoscopy to avoid malposition and injury. Double lumen tubes allow selective ventilation and treatment of each lung but require replacement with a single tube after surgery.
The document summarizes the major physiological changes that occur during pregnancy across multiple body systems. Hormonal changes including increased progesterone, estrogen, prolactin, and cortisol levels help prepare the body for pregnancy. The pancreas produces higher insulin levels to regulate increased blood sugar levels and fuel metabolism. The uterus grows substantially larger to accommodate the fetus, and other organs like the cervix, vagina, blood vessels, and respiratory system also undergo changes. Weight gain during pregnancy of 11-16 kilograms is distributed between increased fluid, tissues, the placenta and developing baby. Most systems return to their pre-pregnancy state after delivery.
Physiological changes during pregnancy can be extensive. The uterus grows dramatically in size and the cervix softens. The breasts enlarge and darken. Throughout pregnancy, the body retains more fluid and blood volume increases. Respiration increases to support higher oxygen needs. The heart works harder pumping more blood. The kidneys and liver increase in size. Many hormonal changes prepare the body for childbirth and nurturing a baby.
Physiological changes in pregnancy affect many body systems. The cardiovascular system adapts to support the growing fetus through increased blood volume, cardiac output, and stroke volume. The respiratory system increases minute ventilation and oxygen consumption while functional residual capacity decreases. The placenta allows passage of most anesthetic drugs from mother to fetus through passive diffusion. Anesthesiologists must consider these physiological alterations when planning anesthetic care for pregnant patients.
Liver transplantation & its anaesthetic managementSwadheen Rout
Liver transplantation requires careful anaesthetic management due to the extensive pathophysiological changes that occur in patients with end-stage liver disease. The three main challenges are secondary organ dysfunction, metabolic derangements, and maintaining haemodynamic stability during the complex surgery. Thorough preoperative evaluation and optimization of organ systems is essential to reduce perioperative risks. Invasive monitoring is important to guide fluid management and vasopressor use during hemodynamic fluctuations.
Ischaemic heart disease & its anaesthetic implicationsSwadheen Rout
This document discusses ischaemic heart disease and its anaesthetic management. It provides an overview of ischaemic heart disease, including its prevalence and risk factors. It then covers the physiology of myocardial oxygen supply and demand, and how an imbalance can lead to ischemia. The document outlines goals and approaches for pre-operative cardiac assessment, including evaluating risk, indications for further testing, and optimization of medical management for high-risk patients. Pre-operative optimization may include starting beta blockers, continuing medications, and consideration of coronary revascularization for selected patients.
The document discusses the history and pharmacodynamics of inhalational anesthetics. It summarizes that no single individual discovered anesthesia, but rather discoveries were made across scientific disciplines by curious individuals. It then discusses several landmark discoveries and uses of anesthetic agents from the 18th century onward. The document also summarizes some of the leading theories about how anesthetic agents produce their effects, including lipid solubility theories and theories related to their interactions with lipid bilayers and proteins like ion channels. Finally, it briefly discusses sites of anesthetic action in the body and factors that can influence their potency.
During pregnancy, the female body undergoes many physiological changes to support the growing fetus. The genital organs like the uterus, cervix, and breasts enlarge and the vascularity increases. The cardiovascular system works harder - blood volume, heart rate, and cardiac output increase. Respiration also increases to supply more oxygen to the mother and fetus. Hormonal changes driven by the placenta result in further physical adaptations like skin pigmentation and breast development. These changes help create a healthy environment for the baby to develop over the 9 months of pregnancy.
Detailed account of the various changes that occur in maternal anatomy, physiology, and metabolism of pregnant women. These physiological changes are often very precise, and deviations of physiological responses can be a prelude to possible disease/infectious states. In this second part of Labor, we will examine the various systems of the human body,its altered states during pregnancy, and how those changes affect the woman preparing for delivery. Special care is imperative in properly determining the needs of an expecting mother, so developing an intimate, trusting relationship between the mother and fully understanding her physiological output will lead to the best chances of a successful delivery.
Physiological changes in pregnancy include changes in the central nervous, respiratory, and cardiovascular systems. The minimum alveolar concentration of anesthetic gases decreases by up to 40% due to hormonal and endogenous changes. Oxygen consumption and minute ventilation increase while functional residual capacity decreases, increasing the risk of desaturation. Blood volume and plasma volume increase substantially, elevating cardiac output and stroke volume and decreasing systemic vascular resistance.
Anaesthetic management of a patient with mitral stenosis put for non-cardiac ...Ankur Khandelwal
Mitral stenosis is a narrowing of the mitral valve that causes obstruction of blood flow from the left atrium to the left ventricle. Rheumatic fever is the most common cause. Symptoms range from none in mild cases, to shortness of breath with exertion in moderate cases, to shortness of breath at rest in severe cases. Diagnosis is made through echocardiogram which can assess the severity based on metrics like mitral valve area and pressure gradients. Treatment depends on symptoms and severity, ranging from medications and lifestyle changes in mild cases, to balloon valvuloplasty or surgical commissurotomy in moderate to severe cases. Anesthetic management aims to avoid tachycardia and
This document discusses pregnancy and valvular heart disease. It notes that pregnancy places significant strain on the heart and can negatively impact both mother and fetus if the mother has an existing heart condition. It provides details on physiological changes during pregnancy and delivery that impact the cardiovascular system. It then reviews specific valvular conditions like mitral stenosis, aortic stenosis, and mechanical heart valves. It recommends carefully planning and monitoring pregnancies for women with valvular disease, with vaginal delivery preferred in most cases depending on the severity of the condition. Close follow-up is important to monitor for complications.
A pregnant women with valvular heart diseaseescardio
This document presents the case of a 28-year-old pregnant woman with known but uninvestigated valvular heart disease. Echocardiography revealed severe mitral regurgitation with mild mitral stenosis and mild aortic regurgitation. Close monitoring during pregnancy showed the condition was well tolerated without treatment. A multidisciplinary team recommended vaginal delivery with monitoring due to the risks of cardiac surgery during pregnancy. Delivery was successful at term with a healthy baby. The key messages were that regurgitant valve disease can be tolerated in pregnancy if left ventricular function is normal, cardiac surgery should be avoided, and multidisciplinary management including delivery planning is important.
This document discusses the case of a female patient presenting with palpitations, breathlessness, and fatigue. Her history reveals rheumatic heart disease diagnosed at age 12. Examination finds a mid-diastolic murmur at the apex, and echocardiogram shows mitral stenosis with a mitral valve area of 2.0 cm2. The patient is diagnosed with mild mitral stenosis of rheumatic origin, without congestive cardiac failure. The document then discusses the anatomy, pathophysiology, symptoms, complications and treatment of mitral stenosis, as well as relevant considerations for anaesthetic management.
The document discusses the case of a 26-year-old female patient who is 36 weeks pregnant with mitral stenosis. She presents with palpitations, breathlessness, and fatigue. Her history and examination are consistent with mild mitral stenosis of rheumatic origin, as confirmed by echocardiogram findings of a mitral valve area of 2.0 cm2 and transvalvular pressure of 8 mm Hg. The discussion centers on the pathophysiology, diagnosis, and management of mitral stenosis, including the plan for regional anesthesia for her elective caesarean section.
Valvular heart disease, specifically mitral stenosis, places a hemodynamic burden on the heart over time. The disease results in a narrowed mitral valve opening that obstructs blood flow from the left atrium to the left ventricle. This obstruction can lead to elevated left atrial pressure and pulmonary hypertension. Symptoms include breathlessness and fatigue. Echocardiography is used to evaluate the severity based on mitral valve area and pressure gradients. Treatment involves managing symptoms medically or surgically replacing/repairing the valve. Anesthetic management focuses on maintaining preload, controlling heart rate, and avoiding pulmonary vasoconstriction.
This document summarizes several physiological changes that occur during pregnancy. Key changes include increased blood volume, cardiac output, and respiratory rate. Hormonal changes lead to decreased sensitivity to local anesthetics and inhalational agents. The supine position can cause issues late in pregnancy due to compression of the inferior vena cava and aorta. Regional techniques require lower doses of local anesthetics during pregnancy. Overall, pregnancy results in significant cardiovascular and respiratory adaptations to meet increased metabolic demands of the mother and fetus.
Obstetric physiology by dr shalini[208736]Manu Gupta
Pregnancy produces significant physiological changes that increase as it progresses. These include hormonal alterations, increased oxygen and metabolic demands, and mechanical effects of the growing uterus. Key cardiovascular changes are a 30-50% increase in cardiac output, 30% increase in blood volume, and 15-20% decrease in peripheral resistance. Respiratory changes include a 50% increase in minute ventilation and 20-50% rise in oxygen consumption. Renal blood flow and glomerular filtration rate increase by 50%. These changes help meet the demands of pregnancy but may complicate anesthesia care.
Physiological Changes in pregnancy and Anaesthetic implications.pptxPritPal24
The document summarizes several physiological changes that occur during pregnancy and their implications for anesthesia. Key changes include increased blood volume, cardiac output and lung volume. Regional blocks require lower drug doses due to increased sensitivity. Opioids readily cross the placenta so their use is limited in labor. Neuraxial techniques provide effective labor analgesia with less fetal exposure than parenteral opioids. Positioning is important to prevent supine hypotension from aortocaval compression.
The document discusses the physiological changes that occur during pregnancy and their implications for anesthesia. Some key changes include increased blood volume, cardiac output and decreased systemic vascular resistance. This causes issues like supine hypotension syndrome. Respiratory changes like decreased functional residual capacity can lead to rapid desaturation. Coagulation changes put the pregnant woman at higher risk for thromboembolism. Anesthetic techniques must account for these changes like positioning to avoid supine hypotension and protecting the airway due to decreased lung volumes.
Pregnant patients are admitted in ICU with a number of pregnancy related problems. Some of them are really life threatening. Identification and prompt action is the key to save lives.
Physiological changes in pregnancy.pptxfarhafatima11
1) Physiological changes in pregnancy include increased weight, blood volume, cardiac output and decreased FRC.
2) Respiratory changes include increased oxygen consumption and minute ventilation but decreased FRC leading to risk of atelectasis.
3) Renal changes involve increased GFR and decreased resorption causing mild glycosuria and proteinuria.
4) Hematological changes result in a hypercoagulable state with increased clotting factors and decreased platelets.
Physiologic changes during pregnancy.pptxTadesseFenta1
Physiological changes during pregnancy alter the body's response to anesthesia. These changes begin early in pregnancy and progress significantly. By term, there are reductions in MAC values (up to 40%), sensitivity to local anesthetics (up to 30%), and FRC (up to 20%). Pregnant women also experience increased oxygen consumption (20-50%), minute ventilation (40-50%), cardiac output (up to 50%), blood volume (45%), and risk of aspiration. Anesthesia requires accounting for these changes through techniques like left uterine displacement, preoxygenation, and rapid sequence induction.
Anesthetic Considerations of Physiological Changes During Preg.pptZIKRULLAH MALLICK
During pregnancy, physiological changes alter the response to anesthesia. The respiratory system adapts to increased oxygen consumption through higher minute ventilation and respiratory drive. Cardiovascular changes include increased blood volume, heart rate, and stroke volume. Supine hypotension can occur due to compression of the inferior vena cava. Anesthetic agents readily cross the placenta and can depress the fetus, so doses must be carefully titrated. Labor further increases oxygen demand and the risk of supine hypotension due to uterine contractions displacing blood from the uterus into central circulation.
Anatomical & physiological changes in pregnancy & their clinical implications...alka mukherjee
The document discusses the anatomical and physiological changes that occur during pregnancy and their clinical implications. It summarizes that during pregnancy, the body undergoes various changes to support fetal growth and development, including increases in blood volume, cardiac output, and lung capacity. These changes are driven by increased levels of estrogen and progesterone from the placenta. Most changes revert back to pre-pregnancy levels by 6 weeks postpartum. Understanding these normal adaptations is important for managing pregnant patients and recognizing how pre-existing conditions may be impacted.
This document discusses respiratory issues that can occur during pregnancy, including common causes of acute respiratory failure in pregnant women. Some key points include:
- Respiratory failure accounts for 40-50% of ICU admissions of pregnant women and has a 12% mortality rate.
- Hormonal and anatomical changes during pregnancy can affect the upper respiratory tract, lungs, and diaphragm.
- Common causes of respiratory failure mentioned include asthma, pneumonia, pulmonary edema, pulmonary embolism, aspiration, anemia, and peripartum cardiomyopathy.
- Management of conditions like asthma and cardiac arrest during pregnancy requires special considerations due to the risks to both mother and fetus. Fetal monitoring and timely delivery
This document summarizes the case of a 42-year-old, 137 kg female patient at 38 weeks gestation with severe aortic stenosis and chronic hypertension admitted for induction of labor due to increasing shortness of breath. Key issues include managing the patient's comorbidities during labor and delivery while maintaining hemodynamic stability given her fixed cardiac output from aortic stenosis. Anesthetic plans focus on careful titration of regional techniques or general anesthesia to prevent rapid hemodynamic changes.
This document summarizes the physiological changes that occur during pregnancy and their implications for providing anesthesia. Key changes include increases in blood volume, cardiac output, lung minute ventilation and renal blood flow. The uterus receives 20% of total blood flow and compresses major blood vessels in the supine position. Drug pharmacokinetics are altered by changes in protein binding, organ blood flows and placental drug transfer. Close monitoring is needed due to sensitivities to medications and risks like aspiration or hypotension from regional techniques. Proper positioning, fluid management and drug dosing can help compensate for physiological adaptations to support the health of both mother and fetus.
Pregnancy poses significant risks for patients with mitral stenosis due to physiological changes that can exacerbate the condition. Careful medical management is needed to minimize risks during pregnancy, labor, delivery and postpartum. Anesthesia goals are to avoid tachycardia, maintain preload and systemic vascular resistance. Epidural analgesia and invasive monitoring are recommended for labor and cesarean delivery. Close monitoring in the postpartum period is also important due to risks of pulmonary edema from autotransfusion.
PHYSIOLOGICAL CHANGES IN PREGNANCY AND ITS ANAESTHETIC IMPLICATIONS.pptxKeerthy Unnikrishnan
The document provides information on the anatomical and physiological changes that occur during pregnancy. It discusses changes in various body systems like cardiovascular, respiratory, gastrointestinal and renal systems due to hormonal changes and increasing size of the uterus and fetus. It also summarizes the fetal circulation pattern and how it differs from adult circulation. The key points are:
1. Hormonal changes and increasing size of uterus causes anatomical and physiological changes in mother's body to support the growing fetus.
2. Cardiovascular changes include increased blood volume, cardiac output and sensitivity to medications. Respiratory changes are increased minute ventilation and oxygen demand.
3. Fetal circulation has parallel arterial systems with ductus venosus, foramen oval
This document discusses the physiological changes that occur during pregnancy and how they impact anesthesia. It covers hematological, cardiovascular, respiratory, gastrointestinal and other organ system changes. Key points include a 40% increase in maternal blood volume, decreased uterine blood flow in the supine position, decreased FRC making mothers more susceptible to hypoxemia, and increased risk of gastric aspiration due to decreased LES tone. Regional anesthesia is preferred for c-sections to allow mother/baby bonding while avoiding neonatal drug exposure from general anesthesia. Precautions must be taken to prevent hypotension from regional blocks.
The document discusses hypertensive disorders of pregnancy including preeclampsia, eclampsia, and chronic hypertension. Some key points:
- Preeclampsia complicates 7-10% of pregnancies in the US and is a leading cause of maternal death. It is defined as new hypertension and proteinuria after 20 weeks.
- Eclampsia occurs in 1 in 10,000-150,000 pregnancies and is characterized by seizures that cannot be attributed to other causes in women with preeclampsia.
- Magnesium sulfate is the drug of choice for preventing and treating seizures from eclampsia, as it reduces the risk of recurrent seizures by over 50%. However,
Maternal physiology undergoes significant changes during pregnancy to support the growing fetus.
Cardiac output increases by 40-50% by the third trimester due to rises in stroke volume and heart rate, while systemic vascular resistance decreases by 20% due to blood vessel dilation.
Respiratory function also changes with a 50% increase in minute ventilation by the second trimester to support increased oxygen demands of the mother and fetus.
The kidneys experience a 50% rise in glomerular filtration rate by 16 weeks to help regulate fluid balance, as plasma volume expands by 40-50% through sodium and water retention.
Respiratory failure during pregnancy.ppsxSamiaa Sadek
This document discusses respiratory physiology and causes of respiratory failure during pregnancy. It notes the anatomical and functional changes that occur during pregnancy, including elevated diaphragm, increased lung volumes, and decreased functional residual capacity. Causes of respiratory failure include conditions like preeclampsia, amniotic fluid embolism, and pulmonary embolism. The document provides guidance on managing respiratory failure with non-invasive ventilation when possible and invasive mechanical ventilation if needed, emphasizing proper settings and monitoring to support both mother and fetus.
This document summarizes the physiological changes that occur during pregnancy and discusses their implications for anesthesia. Key points include:
- Blood volume, plasma volume, and cardiac output increase significantly during pregnancy to meet demands of the uterus, placenta, and fetus. Regional anesthesia can cause hypotension due to further decreases in peripheral resistance.
- Respiratory function changes include elevated diaphragm and decreased functional residual capacity, making pregnant women more susceptible to hypoxemia. Rapid sequence induction requires pre-oxygenation.
- Gastrointestinal changes like decreased lower esophageal sphincter tone increase risk of regurgitation and aspiration under general anesthesia. Regional techniques are preferred for labor and delivery.
Pregnancy causes significant changes to respiratory and cardiovascular physiology. The lungs experience anatomical changes like upward displacement of the diaphragm and increased chest wall circumference. Pulmonary function is altered with a decrease in FRC and increase in minute ventilation and tidal volume. Maternal blood volume and cardiac output increase significantly. Common respiratory medications for conditions like asthma are generally considered safe during pregnancy, though safety categories vary and long term effects are still being evaluated. Corticosteroids can be used cautiously as well. Overall respiratory management requires understanding how pregnancy impacts disease manifestations and treatment.
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These lecture slides, by Dr Sidra Arshad, offer a quick overview of the physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar lead (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
6. Describe the flow of current around the heart during the cardiac cycle
7. Discuss the placement and polarity of the leads of electrocardiograph
8. Describe the normal electrocardiograms recorded from the limb leads and explain the physiological basis of the different records that are obtained
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10. Define the mean QRS vector
11. Describe the axes of leads (hexagonal reference system)
12. Comprehend the vectorial analysis of the normal ECG
13. Determine the mean electrical axis of the ventricular QRS and appreciate the mean axis deviation
14. Explain the concepts of current of injury, J point, and their significance
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. Chapter 3, Cardiology Explained, https://www.ncbi.nlm.nih.gov/books/NBK2214/
7. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
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These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
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5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
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REGULATION FOR COMBINATION PRODUCTS AND MEDICAL DEVICES.pptx
Physiological changes in pregnancy & its anaesthetic implications
1. Dr. Swadheen kumar Rout
1st year P.G
Dept. of Anaesthesiology
M.K.C.G College & hospital
2. INDIA -204 / 1,00,000 live births.
USA - 7 / 1,00,000 live births.
Although no studies in india, studies in usa have
shown that, 4-5% of total deaths are due to over
zealous anaesthetic practices & its complications.
So one must be familiar not only with the effect of
various drugs and techniques on the pregnant women
and foetus but also the physiological changes in
pregnancy which alter response to anaesthesia.
3. Pregnancy produces profound physiological
changes(adaptive to stress) that become more significant
as pregnancy progresses.
This changes can be due to:
1) Hormonal alteration.
2) Mechanical effect of gravid uterus.
3) Increased oxygen & metabolic requirement.
4) Haemodynamical alteration.
In addition unique challenges - two patients are cared for
simultaneously , Failure to take care can be disastrous for
one or both of them.
5. Fluid retention is the most fundamental systemic change of
normal pregnancy.
The total plasma volume is increased during pregnancy
45%. The most marked expansion occurs in extra cellular
volume (ECV) with some increase in intra cellular water.
The factors contributing –
Increase sodium retention.(RAAS)
Decrease in thirst threshold.
Decrease in plasma oncotic pressure(↓ albumin)
6. At term, maternal blood volume has increased by
1000—1500 mL in most women, allowing them to
easily tolerate the blood loss associated with
delivery.
Normal delivery = 400-500ml blood loss
Cesarean section = 800-1000ml blood loss
Blood volume does not return to normal until 1—2
weeks after delivery
7. Cardiac output(40%) increases to meet accelerated maternal and
fetal metabolic demands. This increase is mostly due to an
increase in stroke volume (30%) as heart rate increases only
slightly (about 15%).
Heart rate elevation occurs in response to increased oxygen
demand.
CO ↑ 40% by 12 weeks
50% for rest of pregnancy
60%-100% during labor & after delivery
CO highest right after delivery (release of aorto-caval compression) due
to uterine contraction.
8. Peripheral vascular resistance (VR) decreases due to
the vaso-dilatory effects of progesterone and the
proliferation of low resistance vascular beds in the
inter-villous spaces of the placenta.
Because of the decrease in peripheral vascular
resistance(inspite of increased CO), arterial blood
pressure does not significantly change or may show a
slight fall in a uncomplicated pregnancy.
Diastolic(20%) > Systolic(8%)
The response to adrenergic agents and vasoconstrictors is
thus blunted.
9. Despite the increase in blood volume, there is no
change in the central venous pressure(CVP) during
pregnancy. This is likely due to dilated systemic and
pulmonary circulations.
Cardiac chambers enlarge and myocardial hypertrophy is
often noted on echocardiography.(eccentric due to
activation of RAAS).
Also show variable ECG
,ECHO,CXR Changes.
10. Effect of Pregnancy on Cardiovascular Investigations
Investigation Findings
Chest radiography Apparent cardiomegaly
Enlarged left atrium (lateral views)
Increased vascular markings
Straightening of left-sided heart border
Postpartum pleural effusion
ECG Right-axis deviation
Right bundle branch block
ST-segment depression on left precordial leads
Q waves in lead III
T-wave inversion in leads III, V2, and V3
Rotation of 15 degrees(QRS axis)
ECHO Trivial tricuspid regurgitation
Pulmonary regurgitation (up to 94% at term)
Increased left atrial size by 12%-14%
Increased left ventricle end-diastolic dimensions by 6%-10%
Inconsistent increase in left ventricle thickness
Mitral regurgitation (28% at term)
Pleural effusion (40% postpartum)
From Gei AF, Hankins GDV: Cardiac disease and pregnancy.
11. Occurs in 20% of women at term.
Aorto-caval compression
Compression of IVCCompression of lower aorta
↓ COP by 24% at term.↓ blood flow to kidneys,
utero-placental circulation &
lower extremeties
Supine Hypotension syndrome
(hypotension associated with pallor, sweating,
or nausea and vomiting)
Decreases in cardiac output can occur in
the supine position after the 28th week of
pregnancy.
Fetal hypoxia
12. Compensatory mechanisms in
unanaesthetised Women
Venous Collaterals ↑ SVR & HR
Paravertebral
Venous plexus
Abdominal
wall
Reduced during general
or regional anesthesia.
Severe Hypotension
Profound Fetal Hypoxia
13. Women with a 28-week or longer gestation should
not be placed supine without left uterine
displacement.
Can be done by
Left lateral decubitus
Tilting the table
Left side down
Rigid wedge (>15 degree)
under
The right hip
Fluid preloading before neuro-axial anesthesia
It does not completely avoid maternal hypotension but
It ↑ maternal COP → preserve utero-placental
blood flow.
14. Physical examination of the term pregnant woman
may also be abnormal with auscultation commonly
revealing a wide, loud, split first heart sound, an S3
sound, and a soft systolic ejection murmur.
Hence essential to differentiate abnormal
cardiovascular changes from normal physiological
changes of pregnancy.
15. • Criteria to diagnose cardiac disease during pregnancy:
1) Presence of diastolic murmurs.
2) Systolic murmurs of severe intensity (grade 3).
3) Unequivocal enlargement of heart (X-ray).
4) Presence of severe arrythmias, atrial fibrillation or
flutter
16. Changes in the respiratory system during pregnancy
involve the upper airways, minute ventilation, lung
volumes, and oxygen consumption.
Major physiological changes occur in the respiratory
system during pregnancy due to a combination of both
hormonal and mechanical factors.
Dyspnoea is a common complaint in pregnancy
affecting over half of women at some stage.
18. Due to increased metabolic demands, Oxygen
consumption (+ 20 - 50%) and minute ventilation(+40
- 50%) progressively increase during pregnancy.
(Increased progesterone sensitizes the central
respiratory center to carbon dioxide – directly
stimulating ventilation)
The pregnant woman thus takes larger Tidal
volumes(40-50%) to eliminate carbon dioxide.
Paco2 decreases to(28—32 mm Hg); significant
respiratory alkalosis is prevented by a compensatory ↓
in pasma HCO3 concentration.
19. Hyperventilation may also increase Pa02.
Elevated levels of 2,3-diphosphoglycerate offset
the effect of hyperventilation (↓PaCO2) on
hemoglobin affinity for oxygen.
The combination of increased 2,3-DPG with
increase in cardiac output enhances oxygen
delivery to tissues.
20. The maternal respiratory pattern changes as the
uterus enlarges
Diaphragm rises up(4cm) compensatory increases in
Antero-posterior diameters
Diaphragm motion not restricted
Chest wall limitation
Thoracic breathing favoured over Abdominal
20% decrease in FUNCTIONAL RESIDUAL CAPACITY(FRC).
* No change in CLOSING CAPACICITY (CC) & VITAL CAPACITY
22. ↓ FRC/CC + ↑O2 Consumption
=
Rapid O2 de-saturation during
periods of apnea (diminished capacity to
tolerate apnea).
Supine Position & Regional Block
further diminishes FRC
Pre-oxygenation prior to induction of general
anesthesia should be given to avoid hypoxemia in
pregnant patients.
Rapid devlopment of hypoxemia
23. Rapid gaseous induction
The decrease in FRC coupled with the increase in minute
ventilation accelerates the uptake of all inhalational
anesthetics.
↓FRC ® less dilution
↑MV ® rapid deep depth
24. Hormonal Changes Capillary engorgement of
respiratory tract mucosa
1) ↑ Incidence of difficult intubation.
2) Trauma and bleeding during
endotracheal intubation.
☼ Repeated attempts at laryngoscopy minimized
☼ Use a small ETT (6 – 7 mm) during GA
25. 1) Progressive decrease in MAC .
40% at term
(Returns to normal by 3rd day postpartum).
Progesterone increases
20 times normal
level at term
β- endorphin surge during
labor & delivery
26. LA requirements for subarachnoid or epidural anaesthesia
are reduced in pregnancy (30%)
a) ↑ diffusion of LA to the receptor site.
b) ↑ sensitivity of nerve fibres to LA (Lower CONCN.
needed).
c) engorged epidural venous plexus.
d) ? raised CSF progesterone levels.
Spinal ligaments including ligament flavum SOFT hence
loss of resistance technique used for regional block may be
masked
CNS : its anaesthetic importance
27. IVC obstruction by enlarging
uterus
Engorged Epidural
Venous Plexus
1) ↓CSF Volume
2) ↓Volume of
Epidural Space
3) ↑Epidural space
Pressure
1,2: This enhances the cephalad spread of LA
during regional blocks.
3 : Predisposes to higher incidence of dural puncture &
intravascular injection
28. The parturient should be considered a full stomach patient
during most of gestation
☼ Upward & ant. displacement of the stomach by the
uterus → Incompetence of gastro-esophageal
sphincter → Gastro-esophageal reflux & aspiration.
☼ ↑ Progesterone → ↓ tone of gastro-esophageal sphincter.
☼ Placental Gastrin → Hyper-secretion of gastric acid.
☼ Gastric emptying → Delayed with labor.
29. Narcotics and anti-cholinergic reduce lower
esophageal sphincter pressure (used with precaution)
For GA:
Pharmacological prophylaxis against aspiration.
Supine position with lateral tilt
No positive pressure ventilation before intubation
Rapid sequence induction.
Sellick’s maneuver
30. Renal vasodilatation increases renal blood flow
early during pregnancy.
↑ Cardiac output(CO) ↑ GFR & ↑ RPF(renal
plasma flow) by 50%.
↑ Renin & Aldosterone level promotes Na+ retention
leading to volume overload.
↓ Renal tubular threshold for glucose & amino acids →
mild glycosuria & proteinuria (< 300mg/d).
31. ↑ GFR ↑ clearance of urea, uric acid and
creatinine
↓ plasma concentrations of
sr. Creatinine & BUN
BUN and Creatinine levels that would be considered
marginally elevated in pre-pregnant patients are usually
indicative of severe renal impairment in pregnancy.
32. Hepatic function and blood flow are unchanged.
A mild ↓ in serum albumin is due to an expanded
plasma volume. Thus, the free fraction of albumin-
bound medications is increased.
A 25—30% decrease in serum pseudocholinesterase
activity is also present at term,but it rarely produces
significant prolongation of SCh action.
Increased cholesterol gall stone
formation(progesterone).
33. ↑ Blood Volume ( up to 90ml/Kg)
↑ by 1000 – 1500 ml at term.
↑ Plasma Volume(45%) > ↑ RBC mass(30%)
Dilutional anemia & ↓ blood viscosity
Facilitates maternal & fetal
exchange of respiratory gases,
nutrients & metabolites
↓ Impact of maternal blood
loss at delivery
34. • Pregnancy leads to a hypercoagulable state, due to,
a) factors VII, VIII, X, XII ,IX ( only factor XI )
b) fibrinogen and FDP's
c) fibrinolytic activity - levels of plasminogen activators
d) antithrombin III
Probably a protective adaptation to lessen the risks
associated with the acute haemorrhage that occurs at
delivery.
Increased risk of thromboembolic disease (Post-Anaesthesia
ambulation )
35. Leucocytosis up to 21,ooo/µL.
↑ ESR
10-20% ↓ in platelet count.(Mild thrombocytopenia not a
contra-indication for neuraxial block).
Marked ↓ cell mediated immunity→ ↑ susceptibility to
viral infection.
36. Pregnancy is Diabetogenic
Human Placental lactogen(HPL)→ relative insulin resistance.
• Biochemically Starvation like state
↓ Blood Glucose & Amino Acid levels.
↑ Free Fatty Acids, Ketones & triglycerides.
To promote fetal growth.
Insulin levels steadily rise during pregnancy
37. Secretion of HCG and elevated levels of estrogens
promote hypertrophy of the thyroid gland.
↑ TBG (↑ T3 & ↑ T4) → Free T3, T4 & TSH remain
normal.
38. • Increased level of relaxin - softening cervix
- relax symphysis pubis
- & pelvic joints
Increased risk of back pain(lax ligaments)
40. Maximally dilates uterine vasculature so autoregulation is absent.
Uterine Blood Flow
Directly proportional to difference between
uterine arterial and venous pressure.
Inversely proportional to uterine
vascular resistance.
Uterine vasculature has abundant α-adrenergic & some β-adrenergic receptors.
Previously , vasoconstrictor agents with predominant β-adrenergic activity
(e.g. Ephedrine) were of choice for hypotension during pregnancy.
Recent studies show that α-adrenengic drugs (e.g.Phenylephrine) have
similar effects causing less fetal acidosis.
42. Placental transfer of anaesthetic agents
Placental transfer of drugs depends on:
1) Molecular weight : < 500 Da cross easily.
2) Protein binding– inversely proportional
3) Lipid solubility: Highly ionized substances have poor lipid solubility.
4) Maternal & fetal pH : affect ionization of the drug.
5) Maternal drug concentration: affected by dose given
and route of administration.
6) Timing of administration.
43. Limited effects if < 1MAC
& delivery within 10 min.
of induction
Cross placenta
freely
Inhalational Agents
Intravenous Agents:
Thipental, ketamine &
propofol
Limited fetal effects in
usual induction doses
(drug distribution,
metabolism & placental
uptake)
Variable effects.Cross placenta freelyOpioids
Most significant respiratory depressant effectsMorphine
Significant respiratory depression peaking 1- 3
hr after administration.
Meperidine
Minimal effect if < 1µg/Kg.Fentanyl
Minimal effects on
fetus.
The highly ionized
property impedes
placental transfer.
Muscle Relaxants
44. Local anesthetics → Placental transfer depends on:
1) pKa.
2) Maternal & fetal pH : Fetal acidosis → higher fetal to maternal
drug ratios . Binding of hydrogen ions to the nonionized form → trapping
of local anesthetic in fetal circulation
3) Degree of protein binding : highly protein bound agents
diffuse poorly across the placenta.
Chloroprocaine has the least placental transfer as it is rapidly
broken down by plasma cholinestrase in the maternal circulation.
45. Effect of labor on maternal physiology
Stages of labor
1st stage 2nd stage 3rd stage
Starts with true labor
pains, ends by full
cervical dilation.
Starts with full cervical
dilation, fetal descent
occurs, ends with complete
delivery of fetus.
Extends from birth of the
baby to delivery of the
placenta.
Latent phase Active phase
Progressive cervical effacement
& minor dilataton (2 – 4 cm).
Progressive cervical dilatation
up to 10 cm.
8 – 12 h in nulliparous
5 – 8 h in multiparous.
Contractions are 1.5- 2 min
apart, last 1 – 1.5 min
15 – 120 min.
15 – 30 min.
46. Intense painful contractions
Maternal hyperventilation
MV ↑ up to 300%.
↑ O2 consumption 60%
above 3rd trimester values
Marked Hypocapnia
PaCo2 < 20 mmHg
Uterine VasoConstriction
(fetal acidosis)
Periods of hypoventilation → transient
maternal & fetal hypoxemia in between
Contractions.
47. Each contraction
Displaces 300 – 500ml blood from
uterus to central circulation.
COP ↑ 45% above 3rd trimesteric value.
Maximum strain on the heart occurs immediately
after delivery.
Uterine intense involution→ sudden relieve of IVC
→ ↑ COP 80% above prelabor values.
48. Summary
To illustrate how all these changes may affect anaesthetic
management, lets imagine performing a general anaesthetic for
caesarean setion and list some key points
1) Careful attention to the assessment of the airway and any
necessary preparation to deal with a potentially difficult airway
in the pre operative period.
2)When positioning the patient on the table, remember to use
either a left tilt of between 15 – 30 degrees on the table or a
wedge under the right buttock to minimize aorto-caval
compression.
3)Venous access often easier due to engorgement of the venous
system
49. 4) Pre oxygenation is essential and should be with a tight fitting
mask for at least 3 minutes.
5) Rapid sequence induction with the application of cricoid
pressure is mandatory. Intubation may be difficult and so
adjuncts for difficult intubation should be available.
6) Once the airway is secured, ventilation should be aimed to
keep the PCO2 in the normal range for pregnancy.
7) The MAC of volatile anaesthetic is slightly reduced.
8) There is decreased sensitivity to endogenous and exogenous
catecholamines and so if vasopressors are required to maintain
adequate blood pressure, the amounts needed may be greater.
10) Extubation should be done with the patient awake and on
their side to reduce the risk of aspiration of gastric contents.