S1: Cardiopulmonary exercise testing Flashcards
What does CPET stand for?
Cardiopulmonary Exercise Testing
What physiological parameters are measured during CPET?
VO2, VCO2, oxygen saturation, ventilation, and heart rate
What is VO2max?
The maximal rate of oxygen consumption during exercise
What formula is used to calculate VO2?
VO2 = (SV x HR) x (CaO2 - CvO2)
What is the significance of anaerobic threshold in CPET?
It indicates the point where lactate accumulation begins
What does a low anaerobic threshold suggest?
Poor oxygen delivery, often due to cardiovascular or pulmonary limitations
What is the respiratory exchange ratio (RER)?
The ratio of VCO2 to VO2
What is the ‘nine-panel plot’ in CPET?
A graphical representation of key CPET parameters
What does an increased VE/VCO2 slope indicate?
Reduced ventilatory efficiency or hyperventilation
How is maximum ventilation predicted during CPET?
(FEV1 x 20) + 20
What is oxygen pulse?
VO2 divided by heart rate, an indirect measure of stroke volume
What is a normal maximum heart rate during CPET?
220 minus age
What does a low heart rate reserve suggest in CPET?
Non-cardiovascular limitation to exercise
How can CPET help predict surgical outcomes?
By assessing anaerobic threshold and overall fitness
What is the ventilatory compensation point?
The point where ventilation increases disproportionately to CO2 production
How does CPET differentiate causes of breathlessness?
By analyzing patterns of VO2, VCO2, and ventilation
What is the normal VO2 at rest?
Approximately 250 ml/min
How does body habitus affect VO2max?
Larger body size often increases absolute VO2max
Why is VO2max a key indicator of cardiorespiratory fitness?
It correlates with endurance and mortality risk
What is the significance of the A-a gradient in CPET?
It helps identify oxygenation issues during exercise
How does hyperventilation appear in a VE/VCO2 slope?
As an increased slope, often due to acidosis or anxiety
What does a reduced VE/VO2 ratio indicate?
Improved ventilatory efficiency
What is the relationship between cardiac output and VO2?
Cardiac output is a primary determinant of VO2
What did Myers et al.’s study conclude about exercise capacity?
It is a powerful predictor of mortality
What is the predicted VO2max formula?
VO2max (ml/kg/min) ≈ 50 - (0.4 x age in years)
Why are ventilatory equivalents important in CPET?
They measure the efficiency of ventilation in clearing CO2 and taking in O2
How is stroke volume estimated during CPET?
Using oxygen pulse (VO2/HR)
What is a hallmark of ventilatory limitation during CPET?
Maximum ventilation approaching predicted levels
What is the clinical utility of CPET in heart failure?
Assessing functional capacity and prognosis
What is the significance of the anaerobic threshold for surgery?
Lower thresholds are associated with higher surgical risk
What parameters are analyzed to assess ventilatory efficiency?
VE/VCO2 and VE/VO2 ratios
How is heart rate recovery analyzed in CPET?
By assessing the rate of HR decline post-exercise
What is the impact of beta blockers on CPET results?
They may affect heart rate response and exercise capacity
What does CPET reveal about pulmonary vascular disease?
Desaturation during exercise indicates potential vascular issues
What role does CPET play in managing unexplained breathlessness?
Identifies potential cardiorespiratory limitations
What is the VO2 plateau, and why is it important?
The point where oxygen uptake no longer increases with workload
How does exercise training modify surgical risk?
By improving anaerobic threshold and cardiorespiratory fitness
What is the relevance of VE/VCO2 slope in heart failure prognosis?
Higher slopes indicate worse outcomes
How does CPET contribute to evaluating fitness for surgery?
By identifying cardiorespiratory reserves and limitations
What is the link between CPET findings and mortality?
Markers of low fitness, like low VO2max, correlate with higher risk
