Respiratory Disease Flashcards
Tidal Volume
Normal breath volume
Functional residual capacity
remaining gas in lung after normal expiration
Vial capacity
max expiration volume after max inspiration
Residual volume
remaining gas in lung after max expiration
Fick’s Law
Diffusion rate is proportional to tissue area, partial pressure difference, solubility f gas in the tissue
DIffusion rate is inversely proportional to Tissue thickness and square root of molecular weight
Diffusion of CO2 vs O2
CO2 diffuses 20 TIMES more rapidly than O2
What are the 5 causes of Hypoxemia
Hypoventilation Anatomic R to L shunt Low inspired O2 Diffusion impairment Ventilaation-perfusion (V/Q) mismatch
What is the definition of Hypoventilation?
High PaCO2 (greater than 40 mmHg)
Shunt
Blood entering arterial system without going through ventilated area of lung
Diffusion impairment
Thickened blood gas barrier
Alveolar hypoxia
vasoconstriction of small pulmonary arteries
Hypoxia Pulmonary Vasconstriction (HPV)
Normal physiologic mechanism to match V:P
PAO2
Partial Pressure of O2 in Alveoli
FiO2
Fraction of inspired O2
PATM
Atmospheric pressure
PH2O
Saturated water vapor pressure at 37C
PaCO2
Arterial CO2
What is the Alveolar gas equation?
PAO2 = FiO2 (PATM-PH2O)-(PaCO2/R)
Alveolar-arterial gradient
Difference between PAO2 and PaO2
Should be less than 10-15mmHg
Arterial O2 to fractional inspired O2 ratio (PaO2:FiO2)
Clinically useful easy to calculate, objective measure of oxygenating ability
What does a Arterial O2 to fractional inspired O2 ratio (PaO2:FiO2) of less than 500 mean?
V:Q mismatch
CaO2
Content of oxygen in blood
What is the equation of CaO2
(1.34x[Hb] x SaO2) + (0.003 x PaO2)
What are the factors affecting ventilation?
PaCO2 Arterial pH PaO2 Pulmonary and airway stretch receptors Body temperature Stress, anxiety, pain
What drugs cause minimal respiratory depression?
Benzodiazepines
Phenothiazines
Alpha 2 agonists
Opioids
What drugs cause significant respiratory depression?
Propofol Etomidate Alfaxalone Ketamine Volatile anesthetics Drug combos
IPPV
Intermittent Positive Pressure Ventilation
PIP
Peak Inspiratory Pressure
PEEP
Positive End-Expiratory Pressure
Peak Inspiratory Pressure
Pressure achieved at the end if inspiration
Positive End-Expiratory Pressure
Pressure maintained in airway to prevent alveolar collapse
When is a mechanical ventilator required?
Equine gas anesthesia
small animal if open thorax, using NMBD or patients with increased ICP
What are the disadvantages of IPPV?
Normal Inspiration
PPV is not physiologically normal
Decreased blood pressure
Pulmonary damage
What are the types of respiratory dysfunction?
Airway obstruction
Pulmonary dysfunction
Extrapulmonary dysfunction
What should you do for animal with pleural effusion or pneumothorax?
Thoracocentesis
Brachycephalic airway syndrome
Long soft palate
Stenotic trachea
Everted laryngeal saccules
stenotic nares
Treatment for hypoxemia
resolve any airway obstruction Positioning: sternal Increase PIP Consider broncodilator PEEP
What is the treatment for Equine colic and hypoxemia?
No delay in starting IPPV High PIP PEEP Bronchodilator Tilt table head up Improve cardiac output Must balance positve pressure ventilation with maintaining BP and CO O2 delivery dependent on CaO2 and CO
