Cardiopulmonary Gas Exchange (03:36)
Practitioners measure heart rate, stroke volume, respiratory rate, and tidal volume to determine response to exercise. Michael Snow describes how each measurement corresponds to each other. A gas exchange study records the amount of carbon dioxide and oxygen an individual expels; a breath by breath analysis is more specific than the traditional test.
Snow describes calculations to determine the oxygen uptake and carbon dioxide production. The Haldane Transformation Assumption also includes nitrogen. During exercise, these numbers increase linearly until anaerobic metabolism needs to supplement VO2 levels.
Ventilatory Response to Work (03:57)
As work increases, tidal volume and respiratory rate will increase to support demand. Hypercapnia is a condition of elevated carbon dioxide. Snow describes normal levels of RR, Vt, and minute ventilation during exercise.
Flow Volume Loop (03:24)
During exercise the tidal breathe will begin to match the expiratory flow-volume envelope. During a ramping bike study, the work rate increases in a linear fashion until anaerobic metabolism begins.
Cardiac Response to Exercise (09:03)
Normal people have a cardiac output around 5, 70 heartbeats per minute, and a stroke volume of 75 ml; during exercise, the cardiac output can increase to around 25. If an individual's analytic threshold is less than 11 kg, surgical risks increase dramatically. Snow describes how to calculate an individual's O2 pulse to determine cardiac response.
Ventilatory Inefficiency in Chronic Heart Failure (02:35)
Snow describes how to calculate a graph and interpret findings. The size of the slope predicts a patient's mortality.
Oxygen Uptake Efficiency Slope (02:54)
High-intensity training improves the slope and reduces cardiac issues. Snow describes how to interpret oxygen uptake efficiency plateau. If a clinician inverts the ventilatory equivalents, heart failure patients can be easily detected.
Conclusion: Cardiopulmonary Gas Exchange and Response to Exercise (CPX) (05:30)
Snow describes how to assess disturbing cardiopulmonary patterns while performing an exercise test. Cardiac patients VO2 max is lower than normal individuals. Carl Wasserman created a graphic to help describe functional impairment and normal response.
Credits: Cardiopulmonary Gas Exchange and Response to Exercise (CPX) (00:24)
Credits: Cardiopulmonary Gas Exchange and Response to Exercise (CPX)
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