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- 3. PURPOSE/GOALS OF ANESTHESIA I.WHAT IS ANESTHESIA? General anesthesia Unconscious in reversible, controlled manner Binds to receptors: Brain - unconsciousness Brainstem - immobility spinal cord Sympathetic response Hypertension Tachycardia tachypnea 5 components of anesthesia: Unconsciousness Amnesia Analgesia Immobility Attenuation of anatomic responses to noxious stimulation
- 4. ACTIONS OF COMMONLY USED ANESTHETIC DRUGS
- 5. ACTIONS OF COMMONLY USED ANESTHETIC DRUGS
- 6. I. WHO GIVES ANESTHESIA?
- 7. I. WHAT ARETHE RISKS OF ANESTHESIA? Sore throat Postoperative nausea or vomiting Dental damage Corneal abrasion Awareness Brain damage Death
- 8. PREOPERATIVE EVALUATION II. PATIENT ASSESSMENT Causes stress and physiologic effects Past and current medical and surgical conditions Anesthesiologist or nurse In person, preoperative clinic, phone interview or web-based questionnaire Healthy patients and emergency surgery – same day evaluation
- 9. Chief complaint Age, height, weight Surgical history Previous anesthetics Family history Medications and allergies Medical problems and systems review PREANESTHETIC EVALUATION
- 10. II. ANESTHETIC PLAN Best approach: Patient Medical history Proposed procedure Ideal anesthetic: Minimum physiologic trespass Optimal surgical conditions Comfortable Expeditious recovery
- 11. II. NIL PER OS STATUS Complications: regurgitation and aspiration Exceptions: Emergency surgeries Trauma Severe pain Nausea and vomiting Intestinal obstruction RAPID SEQUENCE INDUCTION
- 12. II. INFORMED CONSENT Last step Disclose pertinent risks Allow questions Legal guardian or medical proxy
- 13. SOAP-ME S – suction O – oxygen (pre-oxygenate with 100% FiO2 for 5mins) A – airway (appropriately sized tubes, blades and oral/nasal airway) P – personnel (RT, nurse, fellow/attending, sedation provider) M – medications: premeds, induction, paralytic, rescue meds (epi, atropine, fluids) E – equipment: vent, ET, stylet, syringe, stylet, tapes, IV
- 14. II. PREMEDICATION Thorough preoperative consultation --- BEST way IV Benzodiazepine (ie. Midazolam)
- 15. III. INTRAOPERATIVE MANAGEMENT Complications may occur at any time during anesthetic Induction: Unconscious Cardiac and respiratory effects Lower BP Diminished upper airway muscle tone
- 16. III. MONITORING Assess: Oxygenation and perfusion Breath sounds to detect airway problems Body temperature Routine noninvasive monitor ECG BP Pulse oximeter Capnography Temperature
- 18. III. INDUCTION Babies and small children – inhalation induction IV induction is rapid and reliable Combination of drugs Propofol – most common, rapid onset (<60 seconds) Lidocaine
- 19. III. INDUCTION
- 20. III. AIRWAY Preoxygenation Denitrogenation 3 minutes to complete 4 tidal breaths
- 27. III. MAINTENANCE Begins after induction when the airway is secured. May use various IV or inhaled agents The goal of anesthesia ensure unconsciousness and amnesia Immobility muscle relaxation blunted sympathetic reflexes
- 28. III. EMERGENCE Review patient’s hemodynamics and temperature Degree of residual neuromuscular blockade Ensure adequate analgesia for the transition to recovery While assessing readiness for emergence, the anesthesiologist begins to decrease or discontinue IV or inhaled anesthetics. Timing of these changes depends on the type of drugs given and the duration of the administration
- 29. CRITERIA FOR EXTUBATION Awake and responsive Stable vital signs Reversal of paralysis Good hand grip Sustained head lift for 5 seconds Negative inspiratory force ≥20mmHg Vital capacity > 15ml/kg
- 30. IV. POSTOPERATIVE CARE Transfer care to recovery room nurse Requires effective and clear communication to avoid error and harm The person assuming the care must respond and confirm that he/she heard and understands the relayed information Must be hemodynamically stable and normothermic Unstable patient is better left intubated, ventilated and sedated until stable
Editor's Notes
- Good morning. I’m Krystel Lacson and will be reporting about the basics of general anesthesia
- -General anesthesia is a process whereby the patient is rendered unconscious in a reversible, controlled manner. -unconsciousness is induced by binding to specific receptors throughout the brain, brainstem and spinal cord -anesthetics most likely make patients unconscious by acting on the brain, while immobility results from effects on the brainstem **complete paralysis can produce immobility in response to surgical stimulation, although paralysis without unconsciousness can lead to awareness with recall, an uncommon but potentially horrifying complication **muscle relaxation provides optimal conditions for endotracheal intubation and improves surgical exposure during intra-abdominal and intrathoracic procedures Even while paralyzed, the body can mount a robust SYMPATHETIC RESPONSE to surgical stimulation with hypertension, tachycardia and tachypnea. The last element of general anesthesia aims to controll these changes
- Some drugs provide all of the elements of anesthesia, while others have more specific roles. This table shows the actions of some commonly used drugs Potent inhaled agents such as iso/sevo have strong effects on amnesia/unconsciousness and immobility, with dose dependent muscle relaxation and suppression of sympha reflexes IV anes have strong effects of amnesia/unconsciouseness and immobility with no muscle relaxation
- Paralytics such as succs and rocuronium produce muscle relaxation but provides no amnesia/unconsciousness nor suppression of sympa reflexes Opioidsdo not produce unconsciousness ------ and longer acting opioids Sympatolytic drugs provide moderate suppression of sympathetic reflexes
- -There are a variety of medical professionals who will be encountered on an anesthesia rotation -these people are known as qualified anesthesia care providers -they have different backgrounds and training and may work alone or as part of an anesthesia care team So this table shows us the training required, the role played in anesthesia care team and the professional organization they’re under
- Most anesthesia consent forms include a list of possible complications. Some of these are.. -nausea and vomiting – common but transient -dental damage and corneal abrasion – less common but self-limited or repairable -awareness, brain damage, or death – rare but catastrophic **awareness – happens 1 in 10,000 patients, and patient with awareness with recall are at increased risk of this complication after a subsequent anesthetic ** death due to anesthesia is very rare, occurring in fewer than 1 in 100,000 anesthetics
- -Surgery stresses the body and anesthetics have significant physiologic effects, therefore, before giving any anesthetic, anesthesiologists evaluates the patient, looking for problems that might increase the risks -requires knowledge of the patient’s past and current medical and surgical conditions -May be completed in person by an anesthesiologist, by a nurse in preoperative clinic or via phone interview, or web-based questionnaire -and Healthy patients for outpatient surgery and any patient needing emergency surgery may be evaluated on the day of the operation
- 1. Preanes eval begins with chief complaint. In this case, what surgery is needed and why??? ***although this information should be available in the medical records, confirming the site and side of surgery directly with the patient is an important safeguard against wrong-site, wrong-side surgery 2. Next the patient’s age, height and weight are reviewed. Extremes in any of these values can present unique concerns 3. Surgical history can alert the anesthesiologist to significant medical problems 4. Questions about previous anesthetics can help prepare for difficult airway, postoperative nausea and vomiting, and other possible complications 5. Even if a patient has never had anesthesia, family history might reveal malignant hyperthermia, pseudo-cholinesterase deficiency or other heritable problems ***Pseudocholinesterase (soo-doe-koh-lin-ES-tur-ays) deficiency is a rare disorder that makes you sensitive to certain muscle relaxants — succinylcholine or mivacurium — used during general anesthesia. Mivacurium is no longer available in the United States but is sometimes used in other countries. On the day of surgery, the anesth reviews the patient’s history and conducts a focused physical exam with emphasis on the heart, lungs, airway, and if regional anesthesia is planned, the site of the regional anesthetic Most patients need only this focused history and PE before undergoing anesthesia but for those with coexisting disease, additional evaluation is needed
- There are multiple ways to provide anesthetic. Choosing the best approach requires an understanding of each patient, his/her medical history, and proposed procedure Ideal anesthetic should produce minimum physiologic trespass, optimal surgical conditions, and a comfortable and expeditious recovery
- General anesthesia and sedation places patients at risk for regurgitation and aspiration of gastric contents **this complication can produce problems ranging from mild chemical pneumonitis and pneumonia to death To minimize this risk, a patient should fast before an elective anesthetic. This picture shows us the preoperative fasting in general The duration of fasting depends on the type of food or liquid ingested. Despite these NPO guideline, patient may take oral medications with a sip of water on the day of surgery There are exceptions to these rules and these patients may have full stomachs regardless of how long they have been NPO. We may opt to choose RAPID SEQUENCCE induction to quickly secure the airway and minimize the risk of aspiration *parturients are treated as having a full stomach regardless of their last food or liquid intake
- This is the last step in the preop eval, which should be targeted to the patient’s specific risks and concerns. We need to disclose pertinent risks and allow the patient to ask questions In some cases, a legal guardian or medical proxy will give consent Regardless, it is important for the patient to understand and agree with the anesthetic plan Rarely, in life-threathening emergency, anesthesia and surgery may proceed without informed consent
- So in the OR, we use this acronym para guide natin kung okay na ang usual set-up
- Patients stay at PACU prior to OR and dun na natin sila usually sinusundo. And here, we usually give premedications prior to transfer to OR. Many patients are anxious when they are getting ready for a surgery Thorough preoperative consultation with anesthesiologist is the best way to relieve patient’s anxiety So yun nga, the patient may receive a small dose of IV benzodiazepine (midazolam) for additional anxiolysis before entering the OR. **Oversedated patients may not cooperate with moving and positioning in the OR. **Outpatient settings, even small doses of midaz can delay discharge. **we have to remember that Elderly are especially sensitive to its sedating effects
- During induction, we administer drugs that render the patient unconscious and have significant cardiac and respiratory effects. -it Can lower BP by dilating arteries and mostly veins, depressing cardiac function or both. -Diminished upper airway muscle tone which can obstruct breathing -many anesthetics act at the brainstem to decrease respi drive. -we also have Paralytic agents given directly which also affect respiratory muscles
- We should monitor the patient Because anesthetics depress cardiorespiratory function and surgery can increase HR and BP of the patient We must assess blah blah Routine blah blah **ECG provides info about cardiac rate and rhythm, may detect ischemia **BP can vary depending on the depth of anesthesia, degree of surgical stimulation, and patient’s volume status **Pulse ox provides info about adequacy of oxygenation and detects presence of pulsatile blood flow. **Capnography and capnometry detect the adequacy of ventilation. **changes in body temp occur routinely during anesthesia, so hypo or hyperthermia are possible
- The World Health Organization has developed a checklist called “the WHO Surgical Safety checklist” used in operating rooms worldwide to increase safety and reliability Eto po ung routine q&a pagpasok natin ng OR
- -GA begins with induction -babies and small children commonly undergo inhalational induction wherein the patient breathes increasing amounts of anesthetic through a facemask until he or she becomes unconscious **this avoids the need for IV access while the child is awake **may be used in adults who are needle phobic or with poor peripheral venous access -IV induction is rapid and reliable and is the more common choice for older children and adults. -anesthetist usually injects a combination of drugs chosen to quickly anesthetize the patient and provide optimal conditions for airway management and surgery -small doses of Propofol provide sedation and anxiolysis. Larger doses cause loss of consciousness. -patient will remain unconscious for 3-5minutes after an induction dose -we use lidocaine because it can dull the burning sensation and limit BP and HR response to laryngoscopy and intubation -fast acting opioids like fentanyl, sufentanil or remifentanil are effective at blocking the cardiovascular responses to laryngoscopy and surgery Here are other examples of other induction agents
- -after the patient loses consciousness, we often inject paralytic agent such as succs or rocuronium. These drugs act at the neuromuscular junction to produce muscle weakness or total paralysis Succinyl provides most rapid onset of action which lasts for about 10-15mins. Side effects include tachycardia, bradycardia blah blah Rocuronium’s onset of action is about 1-2mins and can last for 30-45mins -depolarizing muscle relaxants produce noncompetetive neuromuscular blockade. Their actions cannot be reversed by anticholinesterases -non-depolarizing muscle relaxants produce competitive neuromuscular blockade. Their residual actions can be reversed by an anticholinesterase **anticholinesterase--neostigmine
- -anesthetics impair respiration and sedatives like midazolam and propofol relax oropharyngeal muscles and can produce airway obstruction, (especially in patients with obstructive sleep apnea. Potent inhaled agents may also obliterate the respiratory response to hypoxemia) -so we must be ready to assist or control the patient’s breathing -because of these effects on airway and respiration, the patient usually breathe 100% oxygen for a few minutes before induction of anesthesia. -this step is used to replace nitrogen in a patient’s lungs with oxygen and is called preoxygenation or denitrogenation -it usually takes 3 minutes for complete denitrogenation -however in emergencies, four tidal breaths of 100% oxygen will suffice -if induction anesthesia merely causes airway obstruction, chin lift and jaw thrust maneuvers may open the airway and allow spontaneous ventilation to resume. -but if respiration is significantly depressed, or patient is apneic, artificial respirations must be provided. -initially, we use face mask and breathing bag attached to the anesthesia machine
- Steps to intubation Ensure completeness of equipment needed. Position the patient. Usually nakaextend ung neck nila Sometimes, cricoid pressure (sellick maneuveer) in needed to get a better view Position laryngoscope
- 5. If with visualized entry point, insert the ET tube, but avoid advancing too far 6. Ensure proper placement of the tube and its depth 7. Remove the guidewire 8. inflate the cuff 9. Confirm position of the tube with stethoscope or in other setting, a chest xray post intubation 10. Lastly, we need to Secure the tube
- -endotracheal tubes are inserted through the larynx and into the trachea. Most ET tubes in adults have a cuff at their tracheal end to separate the lungs from the pharynx. This cuff allows positive pressure ventilation and can protect the lungs against aspiration of gastric contents So sa mga hindi pa po nakaobserve ng intubation, we insert the larynscope until we see the epiglottis So eto na po dapat ang makikita natin sa dulo ng laryngoscope, eto ung base ng tounge, epiglottis, vocal cords and ung cartilage. We insert the ET tube here. The size of the ET tube and depth depends on the size/age/gender of the patient Males: size 8 Female size 7.5 Et depth (age/2 + 12)
- The Mallampati score is one assessment to describe the relative size of the base of the tongue compared to the oropharyngeal opening in hopes of predicting the difficult airway
- The Cormack-Lehane scale describes the best view of the glottis during laryngoscopy, with grades defined by the structures that can be seen, as follows:
- This table shows us why difficult airway is expected. First we have to look externally if there is trauma, large incisors, beard or mustache and large tongue. We have to evaluate if there is adequate mouth opening, hyoid-mentum distance and thyroid to floor of mouth distance. If we have Mallampati score of 3 or 4, presence of obstruction or decreased neck mobility The higher the score, the more likely intubation will be difficult
- Maintenance begins after induction when the airway is secured we may use various IV or inhaled agents to keep patient unconscious throughout the surgery This table shows different inhaled anesthetics and here in VLMC, we mainly use Sevoflourane at the moment. It has a pleasant aroma and is a good choice for inhalation induction with no symphathetic stimulation The goal of anesthesia is to ensure unconsciousness and amnesia, immobility, muscle relaxation and blunted sympathetic reflexes Both propofol if given in continuous IV infusion and the potent inhaled agents provide amnesia and block purposeful movement in response to surgical stimulation. Opioids are commonly given during general anesthesia because they decrease the dose of potent inhaled agents needed to keep the patient unconscious and immobile. They also help minimize the cardiac depression associated with these drugs. Fentanyl is the most common opioid used here at vlmc. With onset of 1-2 mins, duration of 20 mins **And intraoperative opioids can provide postoperative analgesia **during induction desflourane and isoflurane often produce tachycardia, opioids can block this effect. *paralytic agents produce immobility but do not produce unconsciousness or amnesia and if used improperly can leave the patient awake but paralyzed
- As surgery winds down, anesthesiologists prepare the patient for emergence *hypothermia can increase oxygen consumption, impair hemostasis, and delay emergence. *iso/sevoflurane are fat soluble and accumulate in adipose tissue
- So here are the criterias for extubation ----- Risks of extubating too soon include airway obstruction, aspiration and laryngospasm Delaying extubation too long can cause hypertension and tachycardia, increase intracranial pressure and bleeding especially for patients who have undergone surgery on the head and neck Once the patient is extubated and ventilating adequately, patient is transferred back to PACU
- Once at PACU, anesthesiologist must transfer care to recovery room nurse.