Pulmonary Flashcards
Respiratory physiology is related to what law?
Boyle’s (p1v1=p2v2) - explains intrapulmonary pressure changes during respiratory cycle
Intrapulmonary pressure is the pressure within the ____
alveoli
Intrapulmonary pressure is ____ with inspiration and ____ with expiration
negative, positive - oscillates around atmospheric pressure
Intrapleural pressure is the pressure in the _____
potential space between inside of chest wall and lungs
Lungs recoil ____ and chest recoils ____
inward, outward
Intrapleural pressure is ___ with inspiration and ___ with expiration
more negative, less negative (may become positive with forced expiration) - always negative pressure
Lowest intrapulmonary pressure is reached halfway into ____ after that, air ____ lungs raises pressure
inspiration, entering
Highest intrapulmonary pressure is reached halfway into ____ after that, air ____ the lungs reduces the pressure
exhalation, leaving
Intrapleural pressure is more negative in the (dependent/non-dependent?) lung, less negative in the (dependent/non-dependent?) lung
non-dependent, dependent
Normal V/Q
0.8 - alveolar ventilation is
Absolute shunt (V/Q) number, defined and examples
zero- there is no ventilation- desaturated blood from the right heart returns to left without being oxygenated. Babies, atelectesis, pneumo
Absolute dead space (V/Q) number, defined, example
Infinitiy, no perfusion, PE
Causes of low PaO2
Low inspired oxygen, hypoventilation or V:Q mismatch
Equation for PAO2
PAO2 = FiO2 (Patm - PH2O =~713) - PaCO2/0.8
Equation for A-a gradient
PAO2 - PaO2 (can estimate PaO2 by FiO2 x5)
When will increasing oxygen help increase PaO2
If problem is hypoventilation or increasing dead space such as PE
When will increasing oxygen not help increase PaO2
Right to left shunts - atelectasis, PDA - use recruitment breaths, add PEEP, suction, dilators
FEV1 defined
Forced expiratory volume in one second
FVC defined
volume of gas that can be exhaled during forced expiratory maneuver
FEV1/FVC usefulness*
ratio useful in distinguishing between obstructive & restrictive disease
FEF 25-75% defined*
midmaximal expiratory flow, *best test for assessing small airway disease independent of respiratory effort
*FEV 1 normal value
4L/sec
*FVC normal value
5L/sec
*FEV1/FVC normal value
0.8 (80%)
Variable extrathoracic obstruction defined and examples
Inspiration is impaired - negative pressure causes closure of something - vocal cord paralysis, residual paralysis, etc
Variable intrathoracic obstruction defined and examples
Exhalation is impaired - usually tumors of trachea or bronchi- positive pressure very difficult if OET not past obstruction
Fixed large airway obstruction
Outside of the system - plugged or kinked OET
Restrictive lung disease
Decreased lung compliance -> decreased lung volumes -> impaired alveolar ventilation, will have normal looking flow volume loops but will be smaller
Obstructive lung disease
Increased airway resistance results in decreased maximum rate of exhalation
Restrictive lung disease and PFT changes
FEV1 and FVC decreased, FEV1/FVC will be normal to increased, compliance may be as low as 0.02 L/cmH2O where normal is 0.10
Examples of restrictive lung disease
pulmonary edema, aspiration, ARDS, POPE
Chronic intrinsic vs extrinsic restrictive lung disease examples
Intrinsic- Sarcoidosis, drug-induced (amio, bleomycin). Extrinsic- Obesity, pregnancy, kyphosis, spinal cord transection, MD
Anesthesia causes of restrictive lung
pain, NMBA, surgery of thorax, positioning - lithotomy/trend
What causes increased risk of PPC with restrictive lung disease?
Dyspnea limiting activity, vital capacity
Intraoperative lung mgmt of restrictive disease
Larger OET, smaller TV with higher rate and sigh breaths, PIPs 35-45 cmH2O, prolonged inspiratory time, pressure control, consider PEEP, above T10 regional can compromise, utilize peripheral blocks, maintain NMBA to help compliance
What causes post obstructive pulmonary edema (POPE)
Type I follows episode of upper airway obstruction, Type II develops after surgical relief of chronic upper airway obstruction. High NIF causes increased venous return to right ventricle which elevates pulmonary capillary hydrostatic pressure and decreases pulmonary interstitial pressure (increased afterload, decreased EF and CO)
Treatment of POPE
Self limiting usually, sometimes reestablish airway, provide oxygen and or CPAP, PEEP
Emphysema defined
Destructive process involving lung parenchyma that results in loss of elastic recoil of lungs- airway collapse during exhalation, usually preserve PaO2 and CO2
Emphysema PFTs
Decreased FEV1, FEV1/FVC, FEF25/75, Increased RV and possibly FRC and TLC
Chronic bronchitis defined
Hypersecretion of mucus and inflammatory changes in bronchi, copious secretions, tendency for hypoxemia and hypercapnia, respiratory acidosis and pulmonary hypertension leading to RV failure and cor pulmonale
Chronic bronchitis PFTs
FEV1/FVC decreased, FEF 25/75 decreased, increased RV and possibly FRC and TLC
Asthma defined
Chronic airway narrowing due to bronchial hyperactivity with exacerbations, know it is IGE mediated
Cromolyn Sodium use in asthma
Preventative measure for bronchospasm, stabilizes mast cells and prevents release of mediators
COPD regional anesthesia
Above level of T6 not recommended
COPD intraoperative management
Use of volatiles, propofol and/or ketamine for bronchodilation, avoid N2O in emphysematous patients (pulmonary bullae), sensitive to opioids, large tidal volumes with slower RR, increased expiratory time, avoid high PIP, likely avoid PEEP
