Labs Flashcards
(17 cards)
Spirometry
Measures respiratory variables
ECG
Records electrical activity of heart
Pulse pressure
Difference between systolic + diastolic BP (heart of force)
Oximetry
Peripheral O2 saturation
Cardiorespiratory coupling
Examines lung volume changes + effect on heart rate + blood pressure
Sinus arrhythmia
Normal variation in HR during breathing
Inspiration: R-R interval decreases, HR increases
Expiration: R-R interval increases, HR decreases
Valsalva manoeuvre
Forced expiration against a closed glottis
Valsalva phases
Phase I: Initial BP rises - compresses aorta, arterial BP rises
Phase II: Reduced venous return (compression of vena cava), decreased stroke volume, compensatory heart rate increase
Phase III: Rapid BP drop upon breath release
Phase IV: Overshoot in BP (increased venous return + sympathetic activation), heart rate normalisation
Inspiratory gasp
Sudden intake of air causing rapid sympathetic activation
Reduced blood flow to skin
Pulse pressure
Threshold
Minimum stimulus needed to trigger AP
Below threshold small depolarisations
At threshold same amplitude
Increased stimulation frequency
Amplitude decreases
VG Na do not have enough time to reset
Decreased sodium influx
Decreased AP amplitude + slows upstroke
RMP remains the same as low Na permeability at rest
Increased potassium
RMP becomes less negative (depolarisation)
High permeability at rest
Decreased potassium
RMP becomes more negative (hyperpolarisation)
Tetradoxin (TTX)
Blocks VG Na channels
Suppresses AP at low conc
Diaminopyridine (DAP)
Blocks VG K channels
Prolongs AP by preventing repolarisation
Lidocaine
Blocks VG Na channels
Suppresses AP better at higher frequency use
Treatment of arrhythmia
