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 ...
This slide summarize all the ways to measure the blood pressure in an very easy manner.This slide specially explains all invasive methods of blood pressure measurement with real world images and examples.
Lung volumes and lung capacities refer to the volume of air in the lungs at different phases of the respiratory cycle.
The average total lung capacity of an adult human male is about 6 litres of air.[1]
Tidal breathing is normal, resting breathing; the tidal volume is the volume of air that is inhaled or exhaled in only a single such breath.
The average human respiratory rate is 30–60 breaths per minute at birth,[2] decreasing to 12–20 breaths per minute in adults.[3
Pulmonary function tests (PFT) are series of tests that measure lung function and aid in the management of patients with respiratory disease.
They are performed using standardized equipment and can be used for diagnosis, prognostication, management and follow-up of patients with pulmonary pathology.
Although PFT may not identify the exact pathology, it broadly classifies respiratory disorders as either obstructive or restrictive. In this session , the role of PFT in the measurement of lung mechanics and diagnosis of various diseases will be discussed in detail.
PULMONARY FUNCTION TESTS - LAB DATA INTERPRETATIONLincyAsha
PULMONARY FUNCTION TESTS
LAB DATA INTERPRETATION
CLINICAL PHARMACY PRACTICE
M.PHARMACY
PHARMACY PRACTICE
1ST YEAR
Pulmonary function tests are a series of tests performed to examine a patient’s respiratory system and identify the severity of pulmonary impairment.
These tests are performed to measure a patient’s lung volume, capacity, flow rate and gas exchange.
This allows medical professionals to obtain an accurate diagnosis and determine the best course of medical intervention for the patient.
In general there are two types of lung disorders that these tests can be used to assess
Obstructive lung diseases
Restrictive lung diseases
1.OBSTRUCTIVE LUNG DISEASES
It include conditions that make it difficult to exhale air out of the lungs
This results in shortness of breath that occurs from narrowing and constriction of the airways and causes the patient to have decreased flow rates. Eg. COPD, Asthma
2.RESTRICTIVE LUNG DISEASES
It include conditions that make it difficult to fully fill the lungs with air during inhalation.
When the lungs aren’t fully able to expand it causes the patient to have decreased lung volumes. Eg. Pulmonary fibrosis, interstitial lung disease
Pulmonary function tests would be indicated for the following:
On healthy patients as part of a routine physical exam
Evaluate signs and symptoms of lung disease
Diagnosis of certain medical conditions
Measure current stage of disease and evaluate its progress
Assess how a patient is responding to different treatments
Determine patient’s condition before surgery to assess the risk of respiratory complications
Screen people who are at risk of pulmonary disease
Determine how much a patient’s airways have narrowed due to disorders
In certain types of work environments to assess the health of employees.
Additionally PFTs may be indicated for the following
Chronic lung conditions
Restrictive airway problems
Asthma
COPD
Shortness of breath
Impairment or disability
Early morning wheezing
Chest muscle weakness
Lung cancer
Respiratory infections
STATIC LUNG VOLUMES
Lung volume is the amount of air breathed by an individual under a specific condition.
1.Tidal Volume (TV)
It is the volume of air inspired or expired during normal breathing at rest.
2.Inspiratory Reserve Volume (IRV)
It is the volume of air inspired with maximum effort over and above the normal tidal volume.
3.Expiratory Reserve Volume (ERV)
It is the volume of air expired forcefully after a normal respiration.
4.Residual Volume (RV)
It is the volume of air remaining in the lungs after a forceful expiration
STATIC LUNG CAPACITIES
1.Inspiratory capacity (IC)
It is the amount of air a person can inspire forcefully after a normal respiration.
IC = TV+IRV
2.Functional Residual Capacity (FRC)
It is the amount of air that remains in the lungs at the end of normal respiration.
FRC = ERV+RV
3.Vital Capacity (VC)
It is the maximum volume of air exhaled forcefully from the lungs after a maximum inspiration.
4.Total Lung Capacity
This is an amazing article giving brief clinical application of PFT.
Bedside PFT are best explained here.
Bedside PFT references most of times are incomplete and inadequate
COURTSEY -DEPARTMENT OF ANESTHESIA, MAMC and LOK NAYAK HOSPITAL, NEW DELHI
pediatric plastic anethesia cleft lip and palate.pptxmohamed abuelnaga
lecture about anaesthesia management for cleft lip and cleft palate surgery. what is the best anaesthesia technique .what is the best analgesic modality for perioperative pain control. how to perform trigeminal nerve block .role of acupuncture in management of postoperative
pain and agitation.
cerebral vasospasm carries a high risk of mortality and morbidity following aneurysmal SAh. the accurate mechanism of vasospasm is still not fully understood.
mechanism oriented management is the best way for disease management. several recent mechanisms of vasospasm as well as recent methods of management have developed.
new technique for pain management ,described by dr forero ,it can replace epidural anesthesia,paravertebral anesthesia and other regional blocks.it can be used for both acute and chronic painful conditions
different causes of low back pain,how to diagnose low back pain ,interventional management for low back pain ,evidence based interventions ,color real photos for different interventions
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
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
MANAGEMENT OF ATRIOVENTRICULAR CONDUCTION BLOCK.pdfJim Jacob Roy
Cardiac conduction defects can occur due to various causes.
Atrioventricular conduction blocks ( AV blocks ) are classified into 3 types.
This document describes the acute management of AV block.
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
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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
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
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
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- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
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2. Pulmonary function tests is a generic term used to
indicate a battery of studies or maneuvers that may
be performed using standardized equipment to
measure lung function.
Evaluates one or more aspects of the respiratory
system:
– Respiratory mechanics
– Lung parenchymal function/ Gas exchange
– Cardiopulmonary interaction
Introduction
4. Only spirometry enables the detection of COPD years before shortness of
breath develops
Enright PL, Hyatt RE, eds. Office Spirometry: A Practical Guide to the Selection and Use of Spirometers.
Philadelphia, PA: Lea & Febiger, 1 987. Used with permission of Mayo Foundation for Medical Education
and Research.
5. @Lung resection
@H/o smoking, dyspnoea
@Cardiac surgery
@ Upper abdominal surgery
@ Lower abdominal surgery
@ Uncharacterized pulmonary disease(defined as
history of pulmonary Disease or symptoms and no
PFT in last 60 days)
American College of Physicians
Guidelines
6. • Recent eye surgery
• Thoracic , abdominal and cerebral aneurysms
• Active hemoptysis
• Pneumothorax
• Unstable angina/ recent MI within 1 month
Contraindications
7. A)MECHANICAL VENTILATORY FUNCTIONS OF
LUNG/ CHEST WALL:
• BED SIDE PULMONARY FUNCTION TESTS
• STATIC LUNG VOLUMES & CAPACITIES – VC, IC, IRV ,
ERV, RV, FRC
• DYNAMIC LUNG VOLUMES –FVC, FEV1, FEF 25‐75% ,
PEFR, MVV, RESP. MUSCLE STRENGTH
CATEGORIZATION OF PFT
8. B)GAS‐ EXCHANGE TESTS:
A)Alveolar‐arterial po2 gradient
B) Diffusion capacity
C) Gas distribution tests:-
1)single breath N2 test.
2)Multiple Breath N2 test.
3) Helium dilution method.
4) Radio Xe scinitigram.
9. C)CARDIOPULMONARY INTERACTION:
• Qualitative tests:
1) History , examination
2) ABG
• Quantitative tests:
1) 6 min walk test
2) Stair climbing test
3)Shuttle walk
4) CPET(cardiopulmonary exercise testing)
10. RESPIRATORY RATE
-component of PFT
-Important evaluator in weaning & extubation
protocol
-Increase RR ‐ muscle fatigue ‐ work load ‐ weaning
fails
Bed side pulmonary function tests
11. 1) Sabrasez breath holding test:
Ask the patient to take a full but not too deep breath & hold
it as long as possible
• >25 SEC ‐NORMAL Cardiopulmonary Reserve (CPR)
• 15‐25 SEC ‐ LIMITED CPR
• <15 SEC ‐ VERY POOR CPR (Contraindication for
elective surgery)
25‐ 30 SEC ‐ 3500 ml VC
20 – 25 SEC ‐ 3000 ml VC
15 ‐ 20 SEC ‐ 2500 ml VC
10 ‐ 15 SEC ‐ 2000 ml VC
5 ‐ 10 SEC ‐ 1500 ml VC
12. 2) SCHNEIDER’S MATCH BLOWING TEST:
(MEASURES Maximum Breathing Capacity):
Ask to blow a match stick from a distance of 6” (15
cms) with:‐
Mouth wide open
Chin rested/supported
No purse lipping
No head movement
No air movement in the room
Mouth and match at the same level
13. • Can not blow out a match
– MBC < 60 L/min
– FEV1 < 1.6L
• Able to blow out a match
– MBC > 60 L/min
– FEV1 > 1.6L
• MODIFIED MATCH TEST:
DISTANCE MBC
9” >150 L/MIN.
6” >60 L/MIN.
3” > 40 L/MIN.
14. 3)COUGH TEST:
DEEP BREATH F/BY COUGH
ABILITY TO COUGH
STRENGTH
EFFECTIVENESS
INADEQUATE COUGH IF:
FVC<20 ML/KG
FEV1 < 15 ML/KG
PEFR < 200 L/MIN.
A wet productive cough / self propagated paraoxysms of
coughing – patient susceptible for pulmonary Complication.
15. 4)FORCED EXPIRATORY TIME:
After deep breath, exhale maximally and forcefully & keep
stethoscope over trachea & listen.
Normal FET 3‐5 SECS.
OBS.LUNG DIS. > 6 SEC
RES. LUNG DIS. < 3 SEC
5)WRIGHT PEAK FLOW METER:
Measures PEFR (Peak Expiratory Flow Rate)
Normal MALES‐ 450‐700 L/MIN.
FEMALES‐ 350‐500 L/MIN.
<200 L/ MIN. – INADEQUATE COUGH EFFICIENCY.
16. 6)DE‐BONO WHISTLE BLOWING TEST:
MEASURES PEFR.
Patient blows down a wide bore tube at the end of which is a
whistle, on the side is a hole with adjustable knob.
As subject blows → whistle blows, leak hole is gradually
increased till the intensity of whistle disappears.
At the last position at which the whistle can be blown , the
PEFR can be read off the scale.
18. • SPIROMETRY : CORNERSTONE OF ALL PFTs.
• John hutchinson – invented spirometer.
• “Spirometry is a medical test that measures the volume
of air an individual inhales or exhales as a function of time.
• CAN’T MEASURE FRC, RV, TLC
STATIC LUNG VOLUMES AND CAPACITIES
19. • Good start of test‐ without any hesitation
• No coughing / glottic closure
• No variable flow
• No early termination(> 6 sec)
• No air leak
• The two largest values for FVC and the two largest values
for FEV1 should vary by no more than 0.2L.
Normal values vary and depend on:
I. Height – Directly proportional
II. Age – Inversely proportional
III. Gender
IV. Ethnicity
SPIROMETRY‐Acceptability Criteria
20. PFT tracings have:
Four Lung volumes: tidal volume, inspiratory reserve
volume, expiratory reserve volume, and residual volume
Five capacities: inspiratory capacity, expiratory capacity,
vital capacity, functional residual capacity, and total lung
capacity
Addition of 2 or more volumes comprise a capacity.
22. It can be measured by
– nitrogen washout technique
– Helium dilution method
– Body plethysmography
Measuring RV, FRC
23. • The patient breathes 100% oxygen, and all the
nitrogen in the lungs is washed out.
• The exhaled volume and the nitrogen
concentration in that volume are measured.
• The difference in nitrogen volume at the initial
concentration and at the final exhaled concentration
allows a calculation of intrathoracic volume, usually
FRC
N2 Washout Technique
24. • Pt breathes in and out from a reservoir with
known volume of gas containing trace of helium.
• Helium gets diluted by gas previously present in
lungs.
• eg: if 50 ml Helium introduced and the helium
concentration is 1% , then volume of the lung is 5L.
Helium Dilution technique
25. • Plethysmography (derived from greek word
meaning enlargement).
• Based on principle of BOYLE’S LAW(P*V=k)
• Priniciple advantage over other two method
is it quantifies non‐ communicating gas
volumes.
Body Plethysmography
26. • A patient is placed in a sitting
position in a closed body box
with a known volume
• The patient pants with an
open glottis against a closed
shutter to produce changes
in the box pressure
proportionate to the volume
of air in the chest.
• As measurements done at
end of expiration, it yields
FRC
27. Includes measuring:
• pulmonary mechanics – to
assess the ability of the lung to
move large volume of air quickly
through the airways to identify
airway obstruction
• FVC
•FEV1
•Several FEF values
•Forced inspiratory rates(FIF’s)
•MVV(max voluntry vent.) or MBC
Dynamic lung volumes(forced
spirometry=timed expiratory spirogram)
28. • The FVC is the maximum volume of air that can be
breathed out as forcefully and rapidly as possible
following a maximum inspiration.
• Characterized by full inspiration to TLC followed by
abrupt onset of expiration to RV.
• Indirectly reflects flow resistance property of
airways.
FORCED VITAL CAPACITY
29. Interpretation of % predicted:
80-120% Normal
70-79% Mild reduction
50%-69% Moderate reduction
<50% Severe reduction
FVC
30. FEV1 : the volume exhaled during the first second of the FVC
maneuver.
• Measures the general severity of the airway obstruction
• Normal is 3‐4.5 L
FEV1 – Decreased in both obstructive & restrictive lung
disorders(if patient’s vital capacity is smaller than predicted
FEV1).
Forced expiratory volume in 1sec
(FEV1)
31. FEV1/FVC – Reduced in obstructive disorders.
Interpretation of % predicted:
>75% Normal
60%‐75% Mild obstruction
50‐59% Moderate obstruction
<49% Severe obstruction
32. -Max. Flow rate during the mid‐expiratory part of FVC
maneuver.
-Measured in L/sec
- May reflect effort independent expiration and the status
of the small airways
-Highly variable
- Depends heavily on FVC
- N value – 4.5‐5 l/sec. Or 300 l/min.
Interpretation of % predicted:
>60% Normal
40‐60% Mild obstruction
20‐40% Moderate obstruction
<10% Severe obstruction
Forced mid-expiratory flow 25‐75% (FEF25‐75)
33. • Maximum flow rate during an FVC maneuver occurs in
initial 0.1 sec.
• After a maximal inspiration, the patient expires as
forcefully and quickly as he can and the maximum flow rate
of air is measured.
• Forced expiratory flow between 200‐1200ml of FVC.
• It gives a crude estimate of lung function, reflecting larger
airway function.
• Effort dependent but is highly reproductive.
Peak expiratory flow rates
34. • It is measured by a peak flow meter,
which measures how much air (litres
per minute)is being blown out or by
spirometry.
• The peak flow rate in normal adults
varies depending on age and height.
• Normal : 450 ‐ 700 l/min in males
300 ‐ 500 l/min in females.
• Clinical significance ‐ values of <200/l‐
impaired coughing & hence likelihood
of post‐op complication.
35. • Measures ‐ speed and efficiency of filling &
emptying of the lungs during increased respiratory
effort.
• Maximum volume of air that can be breathed in
and out of the lungs in 1 minute by maximum
voluntary effort.
• It reflects peak ventilation in physiological
demands.
• Normal : 150 ‐175 l/min. It is FEV1 * 35
• <80% ‐ gross impairment.
Maximum Voluntary Ventilation (MVV) or
maximum breathing capacity (MBC)
36. • The subject is asked to breathe as
quickly and as deeply as possible
for 12 secs and the measured
volume is extrapolated to 1min.
• Periods longer than 15 seconds
should not be allowed because
prolonged hyperventilation leads
to fainting due to excessive
lowering of arterial pCO2 and H+.
• MVV is markedly decreased in
patients with
A. Emphysema
B. Airway obstruction
C. Poor respiratory muscle strength
38. • First 1/3rd of expiratory flow is effort
dependent and the final 2/3rd near
the RV is effort independent
• Inspiratory curve is entirely effort
dependent
• Ratio of
– maximal expiratory flow(MEF)
/maximal inspiratory flow(MIF)
– mid VC ratio and is normally 1
FLOW VOLUME LOOPS
39. • flow‐volume loops provide
information on upper airway
obstruction:
Fixed obstruction: constant
airflow limitation on
inspiration and expiration
such as
1. Benign stricture
2. Goiter
3. Endotracheal neoplasms
4. Bronchial stenosis
UPPER AIRWAY OBSTRUCTION
40. Variable intrathoracic obstruction:
flattening of expiratory limb.
1.Tracheomalacia
2. Polychondritis
3. Tumors of trachea or main bronchus
• During forced expiration – high pleural
pressure – increased intrathoracic pressure ‐
decreases airway diameter. The flow volume
loop shows a greater reduction in the
expiratory phase
• During inspiration – lower pleural pressure
around airway tends to decrease obstruction
41. Variable extrathoracic obstruction:
1.Bilateral and unilateral vocal cord
paralysis
2. Vocal cord constriction
3. Chronic neuromuscular disorders
4. Airway burns
5. OSA
• Forced inspiration‐ negative transmural
pressure inside airway tends to collapse it
• Expiration – positive pressure in airway
decreases obstruction
• inspiratory flow is reduced to a greater
extent than expiratory flow
42. Peak expiratory flow reduced so maximum
height of the loop is reduced
Airflow reduces rapidly with thereduction
in the lung volumes because the airways
narrow and the loop become concave
Concavity may be the indicator of airflow
obstruction and maypresent before the
change in FEV1 or FEV1/FVC
Flow volume loop and lung diseases
ASTHMA
43. Airways may collapse during
forced expiration because of
destruction of the supporting lung
tissue causing very reduced flow at
low lung volume and a
characteristic (dog‐leg) appearance
to the flow volume curve
EMPHYSEMA
44. • Improvement in FEV1 by 12‐15% or
200 ml in repeating spirometry after
treatment with Sulbutamol 2.5mg or
ipratropium bromide by nebuliser
after 15‐30 minutes
• Reversibility is a characterestic
feature of B.Asthma
• In chronic asthma there may be only
partial reversibility of the airflow
obstruction
• While in COPD the airflow is
irreversible although some cases
showed significant improvement
REVERSIBILITY
46. • low total lung capacity
• low functional residual capacity
• low residual volume.
• Forced vital capacity (FVC) may be
low; however, FEV1/FVC is often
normal or greater than normal due
to the increased elastic recoil
pressure of the lung.
• Peak expiratory flow may be
preserved or even higher than
predicted leads to tall, narrow and
steep flow volume loop in
expiratory phase.
RESTRICTIVE PATTERN‐flow volume loop
47. ALVEOLAR‐ARTERIAL O2 TENSION GRADIENT:
Sensitive indicator of detecting regional V/Q inequality
N value in young adult at room air = 8 mmHg to up to 25
mmHg in 8th decade (d/t decrease in PaO2)
AbN high values at room air is seen in asymptomatic
smokers & chr. Bronchitis (min. symptoms)
A‐a gradient = PAO2 ‐ PaO2
* PAO2 = alveolar PO2 (calculated from the alveolar gas
equation)
* PaO2 = arterial PO2 (measured in arterial gas)
PAO2:
(PB ‐ PH2O)*FiO2 ‐ (PaCO2/RQ)
TESTS FOR GAS EXCHANGE FUNCTION
48. DIFFUSING CAPACITY
• Rate at which gas enters the blood divided by its
driving pressure
( gradient – alveolar and end capillary tensions)
• Measures ability of lungs to transport inhaled gas
from alveoli to pulmonary capillaries
• Normal‐ 20‐30 ml/min/mm Hg
• Depends on:
‐ thickeness of alveolar capillary membrane
‐ hemoglobin concentration
‐ cardiac output
49. SINGLE BREATH TEST USING CO
• Pt inspires a dilute mixture of CO and hold the breath for
10 secs.
• CO taken up is determined by infrared analysis:
• DlCO = CO ml/min/mmhg
PACO – PcCO
• DLO2 = DLCO x 1.23
• Why CO?
A) High affinity for Hb which is approx. 200 times that of O2
, so does not rapidly build up in plasma
B) Under N condition it has low blood conc ≈ 0
C) Therefore, pulmonary conc.≈0
51. • Stair climbing and 6‐minute walk test
Tests for cardiopulmonary reserve
cardiopulmonary interaction
52. • Shuttle walk
• The patient walks between cones 10 meters apart with
increasing pace.
• The subject walks until they cannot make it from cone to
cone between the beeps.
• Less than 250m or decrease SaO2 > 4% signifies high risk.
• A shuttle walk of 350m correlates with a VO2 max of 11
ml.kg‐1.min‐1
53. Non invasive technique
Effort independent
To test ability of subjects physiological response to cope with metabolic
demands
Physiological Principle
• Exercising muscle gets energy from 3 sources‐ stored energy (creatine
phosphate), aerobic metabolism of glucose, anaerobic metabolism of
glucose
• In exercising muscle when oxygen demand exceeds supply‐lactate starts
accumulating‐ lactate anaerobic threshold (LAT)
• With incremental increase in exercise – expired minute volume, oxygen
consumption per minute, CO2 production per minute increases
Cardiopulmonary Exercise Testing
54. ◦ Anaerobic threshold (> 11 ml/kg/min)
◦ Maximum oxygen utilization VO2 (>20ml/kg/min)
◦ Ventilatory equivalent of O2 (< 35L)
◦ Ventilatory equivalent of CO2 (<42L)
◦ Oxygen pulse (4‐6ml/heart beat)
What To Measure
55. • As an anesthesiologist our goal is to :
1) to identify pts at risk of increased post‐op morbidity
&mortality
2) to identify pts who need short‐term or long term post‐op
ventilatory support.
Assessment of lung function in
thoracotomy pts
56. Calculating the predicted postoperative
FEV1 (ppoFEV1) and TLCO (ppoTLCO):
There are 5 lung lobes containing
19 segments in total with the division of each
lobe.
Pop FEV1=preoperative FEV1 * no. of segments
left after resection
19
• Can be assessed by ventilation perfusion scan. For eg:
A 57-year-old man is booked for lung
resection. His CT chest show a large RUL
mass confirmed as carcinoma:
ppoFEV1= 50*16/19=42%
57.
58. In addition to history , examination , chest X‐ ray,
PFT’s pre‐ operative evaluation includes:
• ventilation perfusion scintigraphy/ CT scan.
• split‐lung function tests:
methods have been described to try and simulate the
postoperative respiratory situation by unilateral
exclusion of a lung or lobe with an endobronchial
tube/blocker or by pulmonary artery balloon occlusion
of a lung or lobe artery
59. There is no single measure that is a ‘Gold standard ‘in
predicting post‐op complication
60. Pulmonary function criteria suggesting increased risk
of post‐operative pulmonary complications for
various surgeries
61. • They act only to support or exclude a diagnosis.
• A combination of a thorough history and
physical exam, as well as supporting laboratory
data and imaging is helpful in developing a
anaesthetic plan for patient with pulmonary
dysfunction.
Yes, PFTs are really wonderful but…
They do not act alone