1 Flashcards
designed for gas exchange. Its prime function is to allow oxygen to move from the air into the venous blood and CO2 to move out. Although the lung performs other functions, its primary responsibility is to exchange gas.
In other words, it extracts oxygen from the ai
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Lung
it extracts oxygen from the air and transfer it into the bloodstream, and then release carbon dioxide from the bloodstream into the atmosphere, in a process of gas exchange.
Lung
Normal Tidal Volume of a Male
500mL
Normal Tidal Volume of a Female
400mL
move between air and blood by simple diffusion that is from an area of high to low partial pressure.
O2 and CO2
An important practical application of respiratory physiology is the
Testing of pulmonary functions
These tests are useful in a variety of settings.
The most important is the hospital pulmonary function laboratory where these tests help in the diagnosis and management of patients with pulmonary or cardiac diseases.
Testing of pulmonary functions
Transport of O2 via the bloodstream to the cells
Oxygenation
Required for metabolism
Oxygen
Is the exhaling of CO2 via the respiratory tract
Ventilation
Is the exhaling of CO2 via the respiratory tract
Ventilation
Is a byproduct of metabolism
Carbon dioxide
measure how well the lungs take in and exhale air and
how efficiently they transfer oxygen into the blood. The
tests measure lung volume and capacity, flow rates and
gas exchange.
PULMONARY FUNCTION TESTS (PFTs)
are used to assess lung function or capacity. The tests
will be performed at rest or during exercise. The results
are standardized (adjusted) based on one’s age, gender,
race, and height.
PULMONARY FUNCTION TESTS (PFTs)
What can pulmonary function tests do?
•Identify the high-risk smoker
•Detect lung disease early
•Determine the strength of breathing muscles
•Evaluate the course of lung disease
•Measure therapy effectiveness
•Determine the cause of shortness of breath
•Evaluate the effects of occupational exposures
•Determine the degree of impairment
•Evaluate the risk of complications after surgery
Types of Pulmonary Function Test
- Spirometry
- Lung Volumes Test
- Gas Exchange Testing (DLCO)
*Maximal Respiratory Pressure - Maximal Voluntary Ventilation (MVV)
- Hig Altitude Simulation Testing
*Pulse Oximetry
*Bronchoprovocation
*Arterial Blood Gases (ABGs)
- the most common type of lung
function test. It measures how much and how
quickly you can move air in and out of your
lungs. This is a very basic breathing test to
assess the amount of air you inhale and exhale
as a function of time. It also calculates the
speed (flow) of air that can be inhaled or
exhaled.
Spirometry
Also known as “body plethysmography”
Lung Volume test
this test measures the
amount of air you can hold in your lungs and
the amount of air that remains after you exhale
(breathe out) as much as you can.
Lung Volume test
These are the most accurate way to measure
how much air the lungs can hold.
Lung Volume test
where the patient sits or stands
inside an air-tight box that looks like a telephone
booth.
Plethysmography
this test measures the extent to which
oxygen passes from the air sacs of the
lungs to the blood.
Gas Exchange Testing (DLCO)
➢ the test is important in assessing many
different lung diseases and involves
normal and deep breathing as well as
holding one’s breath briefly.
Gas Exchange Testing (DLCO)
➢ this measures the maximal amount of air that can be
inhaled and exhaled in one minute. The test, generally
carried out over 15 seconds, will require one to breathe
in and out as forcefully as possible.
Maximal Voluntary Ventilation (MVV)
➢ it can be helpful in assessing the overall function of the
respiratory system. It may be reduced in cases of
asthma, upper airway obstruction, stiffness of the
respiratory system, and with respiratory muscle
weakness.
Maximal Voluntary Ventilation (MVV)
maximal inspiratory pressure followed by maximal
expiratory pressure was obtained from residual
volume and total lung capacity, with the subjects
seated wearing nose clips and with a rigid, plastic
flanged mouthpiece in place.
Maximal Respiratory Pressures
The subjects were connected to a manual shutter
apparatus with the maximal pressures measured
using a manometer.
. Maximal Respiratory Pressures
are global
measures of maximal strength of respiratory
muscles and they are respectively the greater
pressure which may be generated during
maximal inspiration and expiration against an
occluded airway.
-Maximal inspiratory pressure (MIP) and
maximal expiratory pressure (MEP)
also known as “methacholine challenge test”. It is
used to diagnose asthma. It can find out how
“reactive” or “responsive” the lungs are to things
you inhale that can cause asthma symptoms.
.Bronchoprovocation
These symptoms include cough, a tight feeling in
the chest, and shortness of breath.
Bronchoprovocation
➢ this is a test that allows an estimate of blood
oxygen levels in high altitudes. This is particularly
important for patients who have lung disease and
are dependent on oxygen at sea level.
High Altitude Simulation Testing
The results can be used to prescribe the correct
flow of oxygen when you fly or when you are
visiting an area at high altitude.
.High Altitude Simulation Testing
estimates oxygen levels in the blood. For this test, a
probe will be placed on one’s finger or another skin
surface such as the ear. It causes no pain and has few or
no risks.
Pulse Oximetry
estimates oxygen levels in the blood. For this test, a
probe will be placed on one’s finger or another skin
surface such as the ear. It causes no pain and has few or
no risks.
Pulse Oximetry
a test that directly measure the levels of gases, such as
oxygen and carbon dioxide, in the blood.
Arterial Blood Gases (ABGs)
tests are usually performed in a hospital, but may be done
in a doctor’s office.
Arterial Blood Gases (ABGs)
For this test, blood will be taken from an artery, usually in the
wrist where the pulse is measured. Patient may feel brief pain
when the needle is inserted or when a tube attached to the
needle fills with blood. It is possible to have bleeding or infection
where the needle was inserted.
Arterial Blood Gases (ABGs)
is a laboratory test to monitor the
patient’s acid-base balance. It is used to determine the
extent of the compensation by the buffer system and
includes the measurements of the acidity (pH), levels of
oxygen, and carbon dioxide in arterial blood. Unlike other
blood samples obtained through a vein, a blood sample
from an ,_______ is taken from an artery
(commonly on radial or brachial artery).
Arterial Blood Gas)
The normal range for ________ is used as a guide,and the determination of disorders is often based on blood pH
ABGs
HCO3 level is considered because the kidneys
regulate bicarbonate ion levels.
If the blood is basic
The PaCO2 or partial
pressure of carbon dioxide in arterial blood is assessed because the lungs
regulate the majority of acid.
If the blood is acidic,
pH normal range is
7.35-7.45
PaCO2 normal range is
35 - 45 mmHg (respiratory determinant)
PaO2 normal range is
75 - 100 mmHg
HC03 normal range is
22 - 26 mEq/L (metabolic determinant)
Oxygen saturation normal range is
95 - 100%
Base excess normal range is
-2 to +2 mmol/L
is a drug, chelating substance or a chemical that
neutralizes the effects of another drug or a poison.
oxygen from the air and
Antidote
Is a condition that results when a person is submerged in water to
the point they cannot breath.
the bloodstream into the
Near- Drowning
is the most common cause of death in drowning victims,
which results in cardiopulmonary collapse.
Asphyxia
is the most common treatment method after a near-drowning
event.
CPR
is also something that should be
considered if the patient was submersed in cold water.
Temperature management
Airway clearance therapy may also be indicated;
- Bronchoscopy
- Lavage
- Prone positioning technique
Most near - drowning victims develops
ARDS (Acute Respiratory Distress Syndrome)
A respiratory impairment from submersion or immersion in liquid
leading to hypoxia or decreased oxygenation.
Drowning
What exactly happens when you’re drowning?
- Laryngeal spasm -when you’re underwater and can’t get
air. Airway will close and you can’t breathe. - Loss of consciousness -when you cannot re-surface and
get air. - Death
Risk factors associated with drowning
Age – the younger you are, the more likely you are to
drown (under 15)
2. Gender – male
3. Can’t swim (most obvious)
4. Epilepsy
5. Intoxication (around bodies of water)
6. Exhaustion – you can be a very good swimmer but in a
very bad scenario.
is the first and primary concern
SAFETY
Suspected drowning indicate a
Respiratory problem
- Measures O2 saturation in blood
- Slow to indicate change in ventilation
Pulse Oximetry
- measures CO2 in the airway
- Provides a breath- to- breath status of ventilation
Capnography
Factors that influence PFTs:
a. Weight
b. Age
c. Sec
d. Race
e. Altitude
f. Environmental factors
g. Patient’s effort( most important)
a machine that measures residual volume,
functional residual capacity and total lung capacity.
It is the most
accurate test for showing absolute volumes of air in the lungs,
which helps the doctor diagnose any lung issues.
Plethysmograph
can be defined as a syndrome in which the
respiratory system fails to meet one or both of its gas exchange
functions; Oxygenation and Carbon dioxide Elimination
Respiratory failure
Body relies primarily on the _________, the ______, the ________to accomplish effective respiration.
- Central nervous system
- Pulmonary system
- Heart and vascular system
Rapid and significant compromise in the system’s ability to
adequately exchange carbon dioxide and /or oxygen
ARF (Acute Respiratory Failure)
is a rise in PaCO2 (hypercapnia) that occurs
when the respiratory load can no longer be supported by the
strength or activity of the system.
Ventilatory Failure
The most common causes of respiratory/ventilatory Failure are;
• Severe acute exacerbations of asthma and COPD
• Overdose of drugs that suppress ventilatory drive
• Conditions that cause respiratory muscle weakness such as
Guillain-Barré syndrome, Myasthenia gravis and Botulism.
is the volume of air that is inhaled that does not take
part in the gas exchange, because it either remains in the
conducting airways or reaches alveoli that are not perfused or
poorly perfused.
Dead space
is a life-threatening impairment of oxygenation, carbon dioxide
elimination, or both. Respiratory failure may occur because of
impaired gas exchange, decreased ventilation, or both
ARF (Acute Respiratory Failure)
Common manifestations of ARF include:
*Early signs
*Progression of Hypoxemia
* Physical findings
restlessness, dyspnea, fatigue, headache, air
hunger, tachycardia and increased BP.
Early signs
confusion, lethargy, tachycardia,
tachypnea, central cyanosis, diaphoresis, altered
consciousness, and, without treatment, eventually
obtundation, respiratory arrest, and death.
Progression of Hypoxemia:
use of accessory muscles, decreased breath
sounds if patient cannot adequately ventilate
Physical findings:
Types of Respiratory Failure
Type 1 (Hypoxemic)
Type 2 (Hypercapnic / Ventilatory)
Type 3 ( Peri- Operative)
Type 4 (SHOCK)
PO2 < 60 mmHg on room air.
-Defined as a low level of oxygen in the blood (hypoxemia)
without an increased level of carbon dioxide in the blood
(hypercapnia), and indeed the PCO2, may be normal or low.
Type 1 ( Hypoxemic )
PCO2 > 50mmHg
- Caused by inadequate alveolar ventilation; both oxygen and carbon dioxide are affected
- Defined as the buildup of carbon dioxide levels (P.CO₂) that
has been generated by the body but cannot be eliminated.
Type 2 ( Hypercapnic / Ventilatory )
This is generally a subset of type 1
failure but is sometimes considered separately because it is so
common.
Residual anesthesia effects, post-operative pain, and
abnormal abdominal mechanics contribute to decreasing FRC
and progressive collapse of dependent lung units.
➢ TYPE 3 (PERI-OPERATIVE):
Causes of post - operative atelectasis include:
- Decreased FRC
- Supine / Obese / Ascites
- Anesthesia
- Upper abdominal incision
- Airway secretions
secondary to cardiovascular instability.
Describes patients who are intubated and ventilated in the process of resuscitation for shock
o Cardiogenic
o Hypovolemic
o Septic
Type 4 ( Shock )
Hypoxic Respiratory Failure
- Low ambient oxygen
- V/Q mismatch
- Alveolar hypoventilation
- Diffusion problem
- Shunt
( e.g. at high altitude)
Low ambient
(parts of the lung receive oxygen but not enough blood to absorb it, e.g. pulmonary embolism)
V/Q mismatch
(decreased minute volume due to reduced respiratory muscle activity, e.g. in acute neuromuscular disease); this form can also cause type 2 respiratory failure if severe
Alveolar hypoventilation
(oxygen cannot enter the capillaries due to parenchymal disease, e.g. in pneumonia or ARDS)
Diffusion problem
(oxygenated blood mixes with non-oxygenated blood from the venous system, e.g. right-to-left shunt)
Shunt
is clinical, supplemented by measurements of ABGs and chest x- ray.
Diagnosis
may be required to maintain adequate ventilation and oxygenation while the underlying cause is corrected.
• Intubation and mechanical ventilation
Medical Management of Hypoxic Respiratory Failure
- Correct hypoxemia
- Reduce preload
- Reduce after load
- Support perfusion
- Reverse Bronchospasm
- Maintain Oxygenation
2 types of respiratory failure
Hypercapnia ( “pump failure” )
Hypoxemia. (“lung failure”)
- Is a severe form of lung injury
- acute onset
- bilateral pulmonary infiltrate on CxR
PaO2 / FiO2 <200 - Absence of left heart failure
Acute Respiratory Distress Syndrome
is a form of non-cardiogenic pulmonary edema, due to diffuse alveolar injury. This diffuse alveolar damage occurs secondary to an inflammatory process. The initiative of inflammation can be Direct injury to the Lung or indirect injury by systemic causes.
Acute Respiratory Distress Syndrome
ARDS has three phases __________,____________, and __________.
All of them have characteristic clinical and pathologic features.
Exudative
Proliferative
Fibrotic
In this phase, alveolar capillary endothelial cells and type I pneumocytes (alveolar epithelial cells) are injured, and tight alveolar barrier is damaged giving away the entry to fluid and macromolecules. The protein rich edema fluid accumulates in the interstitial and alveolar spaces.
Exudative phase
encompasses the first 7 days of illness after exposure to a precipitating ARDS risk factor. Tachypnea and increased work of breathing result frequently in respiratory fatigue and ultimately in respiratory failure.
Exudative phase
This phase of ARDS usually lasts from day 7 to day 21. Most patients recover rapidly and are liberated from mechanical ventilation during this phase. Despite this improvement, many patients still experience dyspnea, tachypnea, and hypoxemia.
Proliferative Phase
Histologically, the first signs of resolution are often evident in this phase, with the initiation of lung repair, the organization of alveolar exudates, and a shift from neutrophil- to lymphocyte-predominant pulmonary infiltrates.
Proliferative Phase
Most patients with ARDS recover lung function within 3-4 weeks, very few progresses into fibrotic phase that may require long-term support on mechanical ventilators and/or supplemental oxygen.
Fibrotic Phase
RISK FACTORS OF ARDS
• Sepsis
• Aspiration of gastric contents
• Pulmonary contusion
• Pneumonia
• Near drowning
• Smoke inhalation/burn
• Trauma
• Pancreatitis
• Multiple transfusions
• Pulmonary embolism
• Disseminated intravascular coagulation
has been associated with a mortality rate of 25- 58%.
An acute event that typically develops over 4-48 hours.
Acute Respiratory Distress Syndrome
Clinical Disorders Associated with ARDS
Direct Lung Injury
Indirect Lung Injury
Aspiration of gastric contents
Pulmonary contusion
Toxic gas (smoke) inhalation fractures
Near- Drowning
Diffuse pulmonary infection
Direct Lung Injury
Severe sepsis
Major trauma
Multiple long-bone
Hypovolemic shock
Hypertransfusion
Acute pancreatitis
Drug overdose
Reperfusion injury
Post-lung transplantation
Post-cardiopulmonary bypass
Indirect Lung Injury
Common diagnostic tests for patients with potential ARDS;
a. plasma Brain Natriuretic Peptide (BNP) levels
b. Transthoracic echocardiography
c. Pulmonary Artery catheterization - is the definitive method to distinguish between hemodynamic and permeability pulmonary edema.
MEDICAL MANAGEMENT OF ARDS
- Focus: Identification and treatment of the underlying condition
- Aggressive, supportive care must be provided to compensate for the severe respiratory dysfunction
- Circulatory support
- Adequate fluid volume
- Nutritional support
- Supplemental oxygen - used as the patient begins the initial spiral of hypoxemia
- Monitoring of ABG analysis, pulse oximetry and bedside pulmonary function testing
Used as the patient begins the initial spiral of Hypoxemia
Supplemental Oxygen
is a critical part of the treatment of ARDS because it usually improves oxygenation but it does not influence the natural history of the syndrome.
Positive end-expiratory pressure (PEEP)
helps increase functional residual capacity and reverse alveolar collapse resulting in improved arterial oxygenation.
Positive end-expiratory pressure (PEEP)
Is vital in the treatment of ARDS
Adequate Nutritional Support
Caloric Requirement in ARDS is
35 to 45kcal/kg/day to meet daily requirement
______ is the first consideration in ARDS however, ________ may also be required
- Enteral feeding
- Parenteral Nutrition
Goes through the patient’s nose and into stomach
Nasogastric Tube
Goes through the patient’s mouth and into the trachea
Endotracheal tube
Goes through the patient’s mouth and into the trachea
Endotracheal tube
Which warms and moistens the air
Humidifier
Is essential to limit O2 consumption and reduce oxygen needs
Rest
