Pulm/Peds Flashcards
(173 cards)
Normal pH, PaCO2, and PaO2
7.4, 40, 100
Allen test
Check for upper extremity arterial perfusion by occluding both radial and ulnar aa
Metabolic acidosis causes
Increased anion gap: Lactic acidosis, Ketoacidosis, Drug poisoning (Aspirin, Ethylene glycol, Methanol) = MULEPAKS
Normal anion gap: HARDUP = Diarrhea, Renal tubular acidosis, Interstitial nephritis
Metabolic alkalosis causes
Cl- responsive: Contraction alkalosis, Diuretic use, Corticosteroids, Gastric suctioning or Vomiting
Cl- resistant: Hyperaldosterone state, Hyperventilation
Respiratory acidosis PaCO2 and pH
Low pH and High PaCO2
Respiratory alkalosis PaCO2 and pH
High pH and Low PaCO2
How can alveolar-arterial gradient show signs of lung problems
Alveolar-arterial oxygen gradient is ELEVATED when gas diffusion is impaired
A-a = Alveolar O2 (i.e. atmospheric O2) - arterial O2
Expected normal = Patient age/4 + 4A-a = 0.21(760 atm P - 47 tracheal water vapor P) - PaCO2/(0.8 respiratory quotient) - PaO2
Things limiting O2-Hb dissociation
Alkalosis
Hypothermia
Low PCO2
Low 2,3-DPG
Normal PaO2:FiO2
Dissolved to inhaled O2 ratio
On room air = 100/0.21 = ~475
Increasing FiO2 won’t fully correct hypoxia from a shunt, i.e. If a patient is on an oxygen canula, this should be much lower
Meaning of decreased and increased V/Q ratio
Decreased V/Q = better perfusion than ventilation = shunt (Emphysema, fibrosis, edema)
Increased V/Q = worse perfusion than ventilation = dead space (PE, trachea)
Most air and blood in lungs goes where?
Bases of lungs
Pulmonary function tests (PFTs)
Spirometry
Lung Volumes
Diffusing capacity
So why are PFTs useful?
Explain Dyspnea (Asthma vs VCD)
Hypoxemia etiology (COPD vs Vascular disease)
Follow disease over time (FVC test)
Pre-op testing
FEV1 definition, use
Forced expiratory volume in first second, used for FEV1/FVC ratio
Most reproducible flow rate measurement over time
Can give bronchodilator and repeat 15m later in asthma diagnostics
If FEV1/FVC less than 70% = OBSTRUCTION
Obstructive pulmonary diseases
Air can’t get out
Asthma, emphysema, chronic bronchitis
Restrictive pulmonary diseases
Air can’t get in (restrictive = reduced volume)
Pulmonary fibrosis, Hypersensitivity pneumonitis, Sarcoidosis, Silicosis, Neuromuscular (e.g. ALS)
Variable extrathoracic obstruction (laryngeal cancer) pulmonary cycle
Flattening of flow rate on inspiration
Variable intrathoracic obstruction (lung cancer) pulmonary cycle
Flattening of flow rate on expiration
Fixed obstruction (intra- or extrathoracic) pulmonary cycle
Flattening of flow rate on both inspiration and expiration
Tests for lung functional volume
Nitrogen washout and He dilution
COPD pattern of FVC vs TLC
Low FVC and High TLC
Diffusing capacity test, what affects it
DLCO: breathe in CO, see how much diffused in
DLCO = Kco * Va (Equilibrium CO coefficient * alveolar volume)
Membrane thickness, Lung volume, Air trapping, Carboxyhemoglobin
Stridor
Inspiratory sound from turbulent flow below or in the larynx
Extrathoracic obstruction, better with expiration
Stertor
Sound from turbulent flow above larynx (snoring)