1. Hypoxemia, defined as low oxygen levels in arterial blood, can be caused by hypoventilation, low inspired oxygen, right-to-left shunts, ventilation-perfusion mismatching, or diffusion impairment in the lungs.
2. Physical exam and arterial blood gas analysis are used to diagnose hypoxemia and its underlying causes. Treatment focuses on oxygen supplementation, treating the underlying condition, correcting acid-base imbalances, and mechanical ventilation if needed.
3. The causes, mechanisms, diagnosis and management of hypoxemia are complex but critical for treatment of respiratory failure.
Gas exchange between the alveoli and the pulmonary capillary blood occurs by diffusion, as will be discussed in the next chapter. Diffusion of oxygen and carbon dioxide occurs passively, according to their concentration differences across the alveolar-capillary barrier. These concentration differences must be maintained by ventilation of the alveoli and perfusion of the pulmonary capillaries.
Alveolar ventilation brings oxygen into the lung and removes carbon dioxide from it. Similarly, the mixed venous blood brings carbon dioxide into the lung and takes up alveolar oxygen. The alveolar Image not available. and Image not available. are thus determined by the relationship between alveolar ventilation and pulmonary capillary perfusion. Alterations in the ratio of ventilation to perfusion, called the Image not available., will result in changes in the alveolar Image not available. and Image not available., as well as in gas delivery to or removal from the lung.
Alveolar ventilation is normally about 4 to 6 L/min and pulmonary blood flow (which is equal to cardiac output) has a similar range, and so the Image not available. for the whole lung is in the range of 0.8 to 1.2. Image not available. However, ventilation and perfusion must be matched on the alveolar-capillary level, and the Image not available. for the whole lung is really of interest only as an approximation of the situation in all the alveolar-capillary units of the lung. For instance, suppose that all 5 L/min of the cardiac output went to the left lung and all 5 L/min of alveolar ventilation went to the right lung. The whole lung Image not available. would be 1.0, but there would be no gas exchange because there could be no gas diffusion between the ventilated alveoli and the perfused pulmonary capillaries.
Oxygen is delivered to the alveolus by alveolar ventilation, is removed from the alveolus as it diffuses into the pulmonary capillary blood, and is carried away by blood flow. Similarly, carbon dioxide is delivered to the alveolus in the mixed venous blood and diffuses into the alveolus in the pulmonary capillary. The carbon dioxide is removed from the alveolus by alveolar ventilation. As will be discussed in Chapter 6, at resting cardiac outputs the diffusion of both oxygen and carbon dioxide is normally limited by pulmonary perfusion. Thus, the alveolar partial pressures of both oxygen and carbon dioxide are determined by the Image not available. If the Image not available. in an alveolar-capillary unit increases, the delivery of oxygen relative to its removal will increase, as will the removal ...
Gas exchange between the alveoli and the pulmonary capillary blood occurs by diffusion, as will be discussed in the next chapter. Diffusion of oxygen and carbon dioxide occurs passively, according to their concentration differences across the alveolar-capillary barrier. These concentration differences must be maintained by ventilation of the alveoli and perfusion of the pulmonary capillaries.
Alveolar ventilation brings oxygen into the lung and removes carbon dioxide from it. Similarly, the mixed venous blood brings carbon dioxide into the lung and takes up alveolar oxygen. The alveolar Image not available. and Image not available. are thus determined by the relationship between alveolar ventilation and pulmonary capillary perfusion. Alterations in the ratio of ventilation to perfusion, called the Image not available., will result in changes in the alveolar Image not available. and Image not available., as well as in gas delivery to or removal from the lung.
Alveolar ventilation is normally about 4 to 6 L/min and pulmonary blood flow (which is equal to cardiac output) has a similar range, and so the Image not available. for the whole lung is in the range of 0.8 to 1.2. Image not available. However, ventilation and perfusion must be matched on the alveolar-capillary level, and the Image not available. for the whole lung is really of interest only as an approximation of the situation in all the alveolar-capillary units of the lung. For instance, suppose that all 5 L/min of the cardiac output went to the left lung and all 5 L/min of alveolar ventilation went to the right lung. The whole lung Image not available. would be 1.0, but there would be no gas exchange because there could be no gas diffusion between the ventilated alveoli and the perfused pulmonary capillaries.
Oxygen is delivered to the alveolus by alveolar ventilation, is removed from the alveolus as it diffuses into the pulmonary capillary blood, and is carried away by blood flow. Similarly, carbon dioxide is delivered to the alveolus in the mixed venous blood and diffuses into the alveolus in the pulmonary capillary. The carbon dioxide is removed from the alveolus by alveolar ventilation. As will be discussed in Chapter 6, at resting cardiac outputs the diffusion of both oxygen and carbon dioxide is normally limited by pulmonary perfusion. Thus, the alveolar partial pressures of both oxygen and carbon dioxide are determined by the Image not available. If the Image not available. in an alveolar-capillary unit increases, the delivery of oxygen relative to its removal will increase, as will the removal ...
Mechanical ventilation ppt including airway, ventilator, tubings and connections, nursing management, trouble shooting common problems and issues, suctioning etc.
lungs is a vital organ that will help to respiration . in case of respiratory failure the . VQ mismatch will occur and that lead to hypercapnic and hypo capnic respiration
Respiratory failure Concepts with sample mcqs Medico Apps
Respiratory Failure: Concepts and Sample MCQs
(For NEET PG, USMLE, PLAB, FMGE /MCI Screening Entrance Exams)
For more such notes and quizzes visit www.medicoapps.org
For my colleagues and medical students out there who need to either read or present the subject of hypoxia in surgical patients. I hope you find this one helpful.
Acute respiratory failure happens quickly and without much warning. It is often caused by a disease or injury that affects your breathing, such as pneumonia, opioid overdose, stroke, or a lung or spinal cord injury. Respiratory failure can also develop slowly
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
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
Acute scrotum is a general term referring to an emergency condition affecting the contents or the wall of the scrotum.
There are a number of conditions that present acutely, predominantly with pain and/or swelling
A careful and detailed history and examination, and in some cases, investigations allow differentiation between these diagnoses. A prompt diagnosis is essential as the patient may require urgent surgical intervention
Testicular torsion refers to twisting of the spermatic cord, causing ischaemia of the testicle.
Testicular torsion results from inadequate fixation of the testis to the tunica vaginalis producing ischemia from reduced arterial inflow and venous outflow obstruction.
The prevalence of testicular torsion in adult patients hospitalized with acute scrotal pain is approximately 25 to 50 percent
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- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
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Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
Triangles of Neck and Clinical Correlation by Dr. RIG.pptx
Approach to hypoxemia
1. APPROACH TO HYPOXEMIA
DR KALIPRASANNA CHATTERJEE
2ND YEAR PGT
DEPARTMENT OF PULMONARY MEDICINE
BURDWAN MEDICAL COLLEGE
2. DEFINATION
• Arterial hypoxemia is defined as a partial pressure of
oxygen in arterial blood (PaO2) less than 80 mmHg
while breathing in room air.
• Hypoxia is defined as a deficiency in either the
delivery or the utilization of oxygen at the tissue level,
which can lead to changes in function, metabolism
and even structure of the body.
3. CLASSIFICATION OF HYPOXEMIA
This classification is based on predicted normal values for a patient who is less
than 60 years old and breathing room air. For older patients, subtract 1 mm
Hg for every year over 60 years of age from the limits of mild and moderate
hypoxemia.
A PaO2 of less than 40 mm Hg represents severe hypoxemia at any age.
4.
5. CAUSES OF HYPOXEMIA
The mechanisms that cause hypoxemia can be divided into
those that increase P(A-a)O2 and those where P(A-a)O2 is
preserved .
1. HYPOVENTILATION.
2. LOW INSPIRED OXYGEN.
3. RIGHT TO LEFT SHUNT.
4. VENTILATION PERFUSION INEQUALITY.
5. DIFFUSION IMPAIRMENT.
6. HYPOVENTILATION
• Hypoventilation is used here to refer to conditions in which
alveolar ventilation is abnormally low in relation to oxygen
uptake or carbon dioxide output.
• Alveolar ventilation is the volume of fresh inspired gas going
to the alveoli (i.e. Non–dead space ventilation).
• Hypoventilation occurs when the alveolar ventilation is
reduced and the alveolar PO2 therefore settles out at a lower
level than normal. For the same reason, the alveolar PCO2, and
therefore arterial PCO2, are also raised
7. HYPOVENTILATION
• P(A-a)O2 is normal.
• PaCO2 is elevated (hypercapnia)
• Increasing the fraction of inspired oxygen (FIO2) can alleviate
the hypoxemia and the hypercapnia can be corrected by
mechanically ventilating the patient to eliminate CO2.
8. HYPOVENTILATION
• The relationship between the fall in Po2 and the rise in Pco2
that occurs in hypoventilation can be calculated from the
alveolar gas equation if we know the composition of inspired
gas (PIo2) and the respiratory exchange ratio (R).
• A simplified form of the alveolar gas equation is –
9. CAUSES OF HYPOVENTILATION
1. depression of the respiratory center by drugs, such as
morphine derivatives and barbiturates.
2. diseases of the brain stem, such as encephalitis.
3. abnormalities of the spinal cord conducting pathways, such
as high cervical dislocation; anterior horn cell diseases,
including poliomyelitis.
4. affecting the phrenic nerves or supplying the intercostal
muscles;
10. CAUSES OF HYPOVENTILATION
5.diseases of the myoneural junction, such as myasthenia
gravis;
6.diseases of the respiratory muscles themselves, such as
progressive muscular dystrophy; thoracic cage
abnormalities (e.g., crushed chest);
7. diseases of nerves to respiratory muscles (e.g., Guillain-
Barrý syndrome);
8.upper airway obstruction (e.g., thymoma);
9. hypoventilation associated with extreme obesity
(pickwickian syndrome)
10. miscellaneous causes, such as metabolic alkalosis and
idiopathic states.
11. LOW INSPIRED OXYGEN [ PI O2 ]
• Examples-
• A decrease in barometric pressure [e.g. breathing at high
altitude].
• A decrease in FIO2 – accidental [e.g. anesthetist does not
supply enough oxygen or improper installation of oxygen
supply lines or a leak in the breathing circuit].
• P(A-a)O2 normal
• PaCO2 is decreased. This reduction in PaCO2 (hypocapnia) is
due to hyperventilation in response to hypoxemia.
• Peripheral chemoreceptors sense the low arterial PO2 and
initiate an increase in ventilation through their input to the
medullary respiratory centre
12. RIGHT TO LEFT SHUNT
• Shunt refers to the entry of blood into the systemic arterial
system without going through ventilated areas of lung.
• Shunt may be anatomical or physiological.
• P(A-a)O2 is elevated.
• PaCO2 is normal.
13. RIGHT TO LEFT SHUNT
• Anatomic shunt: when a portion of blood bypasses the
lungs through an anatomic channel.
• In healthy individuals
• i) A portion of the bronchial circulation’s (blood supply to the
conducting zone of the airways) venous blood drains into the
• pulmonary vein.
• ii) A portion of the coronary circulation’s venous blood drains
through the thebesian veins into the left ventricle.
• note: i & ii represent about 2% of the cardiac output and
account for 1/3 of the normal P(A-a)O2 observed in health.
14. RIGHT TO LEFT SHUNT
• Congenital abnormalities
• i) intra-cardiac shunt [e.g. Tetralogy of Fallot: ventricular
septal defect + pulmonary artery stenosis]
• ii) intra-pulmonary fistulas [direct communication between a
branch of the pulmonary artery and a pulmonary vein].
15. RIGHT TO LEFT SHUNT
• Physiologic shunt: In disease states, a portion of the
cardiac output goes through the regular pulmonary vasculature
but
does not come into contact with alveolar air due to filling of
the alveolar spaces with fluid [e.g. pneumonia, drowning,
pulmonary edema]
• An important diagnostic feature of a shunt is that the arterial
PO2 does not rise to the normal level when the patient is given
100% oxygen to breathe.
16. RIGHT TO LEFT SHUNT
• Examples of
intrapulmonary shunt.
(a) Collapsed and
fluid filled alveoli are
examples of
intrapulmonary shunt.
• (b) Anomalous blood
return of mixed
venous blood
bypasses the alveolus
and thereby
contributes to the
development of
intrapulmonary shunt.
17. VENTILATION PERFUSION INEQUALITY
• PaCO2 is normal
• P(A-a)O2 is elevated
• VA/Q inequality is the most common cause of hypoxemia in
disease states
18. VENTILATION PERFUSION INEQUALITY
• In normal individuals, there is a spectrum of VA/Q ratios that
range from relatively underventilated units to those lung units
which are ventilated but not perfused.
• In normal lungs, VA/Q may range from 0.6 to 3.0, with the
distribution of all units of the lung in aggregate usually
averaging a VA/Q of approximately one.
19. VENTILATION PERFUSION INEQUALITY
• The distribution of ventilation varies with common events,
such as changes in body posture, lung volumes, and age.
• Increasing age produces a gradual increase in the degree of the
VA/Q inequality.
• Ventilation–perfusion imbalance exists even in the normal
lung, depending on the region, but remains fairly tightly
regulated when assessing normal lung aggregate function
20. VENTILATION PERFUSION INEQUALITY
• In patients with obstructive or restrictive ventilatory diseases,
decreased ventilation may result from structural or functional
abnormalities of the airway and can lead to decreased VA/Q
units
• On the other hand, lung units with increased VA/Q ratios can
develop disorders that lead to over ventilation of lung units,
conditions such as emphysema,for example, in which patients
have airspace enlargement as a result of the destruction of the
alveolar sac distal to the terminal bronchiole.
• Moreover, the development of impaired perfusion through
the pulmonary vasculature, as observed in cases of
pulmonary embolism or pulmonary vasospasm, may cause
high VA/Q ratios
22. VENTILATION PERFUSION INEQUALITY
• Reflex mechanisms are present in the lung to minimize the
effect of VA/Q inequality, thus avoiding or minimizing the
detrimental effects of impaired gas exchange
• One mechanism is hypoxic pulmonary vasoconstriction
(HPV), whereby a fall in VA/Q leads to the development of
alveolar hypoxia which in turn causes vasoconstriction of
the perfusing arteriole.
• This effect is beneficial for pulmonary gas exchange because it
decreases the denominator of the VA/Q relationship, thereby
partially correcting regional VA/Q imbalance and improving
arterial hypoxemia
23. VENTILATION PERFUSION INEQUALITY
• HPV appears to operate over a range of alveolar PO2 values
between 30 and 150 mmHg.
• The mechanism by which alveolar hypoxia sends the message to
trigger regional vasoconstriction is unclear, but may involve the
release of humoral messengers.
• Many factors, however, can significantly interfere with HPV
1. certain drugs such as calcium channel blockers, beta-agonists,
and inhalational anesthetic agents.
• Lower respiratory tract infections or disease processes that cause
elevations in left atrial pressure can also interfere with HPV.
• In addition, although HPV may be helpful in improving arterial
hypoxemia, a progression in vasoconstrictor effect can lead to the
development of secondary pulmonary hypertension and, eventually,
right heart failure
24. DIFFUSION LIMITATION
• It is now generally believed that oxygen, carbon dioxide, and
indeed all gases cross the blood-gas barrier by simple passive
diffusion
• Fick's law of diffusion states that the rate of transfer of a gas
through a sheet of tissue is proportional to the tissue area (A)
and the difference in partial pressure (P1-P2) between the two
sides, and is inversely proportional to the thickness (T)
25. DIFFUSION LIMITATION
• The rate of diffusion is also proportional to a constant, D,
which depends on the properties of the tissue and the particular
gas.
• The constant is proportional to the solubility (Sol) of the gas,
and inversely proportional to the square root of the molecular
weight (MW)
26. DIFFUSION LIMITATION
• PaCO2 is normal.
• P(A-a)O2 is normal at rest but may be elevated during
exercise.
• a rare observation in the clinical setting
27. DIFFUSION LIMITATION
• Diffusing capacity is reduced by diseases in which the
thickness is increased, including diffuse interstitial pulmonary
fibrosis, asbestosis, and sarcoidosis.
• It is also reduced when the area is decreased, for example, by
pneumonectomy.
• The fall in diffusing capacity that occurs in emphysema may
be caused by the loss of alveolar walls and capillaries
31. SYMPTOMS
• Specific organ
symptoms:
• Pulmonary
• Cough
• Chest pains
• Sputum production
• Stridor
• Dyspnea (resting vs.
exertional)
• Cardiac
• Orthopnea
• Peripheral edema
• Chest pain
• Other
• Fever
• Abdominal pain
• Anemia
• Bleeding
32. PHYSICAL EXAMINATION
• Physical examination of patients with hypoxemia begins with
a quick, but thorough, general assessment.
• The initial priority is to triage patients who present with severe
forms of respiratory failure from those with less severe forms.
33. PHYSICAL EXAMINATION
• General findings:
• Mental alertness
• Ability to speak in complete
sentences
• Respiratory rate > 35
breaths/min
• Heart rate > or < 20 beats from
normal
• Pulsus paradoxus present?
• Elevated work of breathing?
• Using accessory muscles
• Rib cage or abdominal paradox
• Specific organ dysfunction:
• Pulmonary:
• Stridor
• Wheezes
• Rhonchi
• Crackles.
• Cardiac:
• Tachycardia, bradycardia
• Hypertension, hypotension
• Crackles
• New murmurs
37. Oxygenation
• Oxygen is frequently necessary for patients who present with
hypoxemia or with conditions known to predispose to
hypoxemia.
• Most of the initial morbidity and mortality that occurs in
patients results from the consequences of untreated
hypoxemia.
38. Oxygenation
• Various types of external oxygen delivery devices are now available to
provide variable concentrations of inspired oxygen.
• The choice of a particular device depends on-
• (1) the magnitude of supplemental oxygen required by the patient to
achieve effective oxygenation;
• (2) the need for precise control of supplemental oxygen to avoid
excessive oxygenation and the development of hypercapnia.
• (3) whether airway control is needed to suction the patient for excessive
secretions.
• (4) whether other techniques are needed to increase oxygen by increasing
lung volume (externally applying positive pressure to the airway by CPAP
or PEE P.
39. Oxygenation
• Nasal prongs:
-simplest and most comfortable method.
-does not provide enriched oxygen in an extremely precise manner.
• Face mask devices:
-fit more tightly and may have non-rebreathing valves that,
coupled with an inspiratory reservoir of oxygen, provide higher
and more precise concentrations of supplemental oxygen.
-delivery of oxygen by means of a face mask with a Venturi device (a
calibrated inline device) can provide high flows of oxygen in a more
precise manner and minimize the effect of room air entrainment.
40. Medications
• The use of medications in the treatment of respiratory failure
depends on the underlying disorder.
• In patients who present with an exacerbation of airway
obstruction, bronchodilators, corticosteroids, theophylline
preparations, and possibly antibiotics, are required.
• In patients who present with pulmonary edema due to volume
overload, or with cardiac dysfunction, diuretics are in order.
• In patients who have more pronounced cardiac dysfunction,
the selected use of cardiac inotropes may be required
41. Supportive Therapy
• Acid–base or electrolyte disturbances may compromise
respiratory pump function and contribute to an elevated
ventilatory workload.
• Hypocalcemia, hypomagnesemia, hypokalemia,and
hypophosphotemia all have been identified as conditions that
lead to skeletal muscle weakness and, specifically, respiratory
skeletal muscle weakness.
•
• Correction of these abnormalities can markedly improve
ventilatory muscle strength and increase respiratory reserve.
42. Supportive Therapy
• Regardless of etiology, metabolic acidosis increases
ventilatory workload and its presence should be identified and
appropriately treated.
• The use of ancillary testing and physical examination must
appropriately diagnose the cause of metabolic acidosis
because effective therapy of this disorder is a crucial part of
the overall treatment plan for respiratory failure
43. Supportive Therapy
• Nutritional support and, in some cases, reconditioning are
also important in restoring respiratory pump function and
reversing the presence of respiratory failure.
• Renutrition increases respiratory muscle mass and restores
ventilatory muscle endurance, an important beneficial
physiologic effect that results in an improvement in respiratory
pump function.
• Moreover, rehabilitation of patients who present in a
deconditioned state, or with disuse atrophy after a critical
illness, is similarly important in restoring respiratory pump
function.
44. Reducing Ventilatory Workload
• In some patients,, ventilatory workload far exceeds capacity,
and the patient’s spontaneous effort must be augmented with
mechanical ventilation until the condition causing the higher
workload resolves or the patient’s ventilatory capacity
increases.
• Augmentation of the patient’s spontaneous breathing effort can
be achieved by either invasive or noninvasive forms of
mechanical ventilation.
• In noninvasive mechanical ventilation,a nasal or nasal oral
face mask is used to augment the patient’s spontaneous efforts
without the use of an artificial airway.
• In the case of invasive ventilation, an artificial conduit is
inserted in the patient’s airway, either an endotracheal tube or
a subglottically placed tracheotomy tube
45. Reducing Ventilatory Workload
• Invasive ventilation is the method most frequently used to
augment a patient’s spontaneous respiratory effort.
• When using invasive ventilation, endotracheal intubation is
considered mandatory for the patient’s therapy so as to-
• (1) provide airway protection.
• (2) serve as a conduit for suctioning patients with excessive
mouth or lower respiratory tract secretions.
• (3) achieve higher inspired oxygen concentrations than are
possible with a face mask.
• (4) apply positive pressure via the ventilator to increase lung
volume to treat refractory hypoxemia.