- CPEX testing
- 1 MET ~ 3.5ml/kg/min
4 MET = 1 flight of stairs - Spirometry, echo and ECG are resting tests
- Treadmill tests requires weight bearing, co-ordination and exercise
- Performing the test
- Adequately ventilated room with resus equipment
- Gas analyser, NIBP, SpO₂,12 lead, graphical displays
- Breath-to-breath analysis to enable V̅O₂ & V̅CO₂ measurement
- Tight fitting mask
- Baseline recorded for 3 mins then continued increase in resistance
- Muscles therefore have increased O₂ requirements
- This needs to be met by an increase in c.o.
- Co increases linearly with V̅CO₂ as does arterial-mixed O₂ difference until peak O₂ extraction ratio is reached (OER)
- AT
- Combined efficiency of the lungs, heart and circulation
- With exercise, O₂ demand will exceed supply => muscles will generate ATP anaerobically producing lactate
- Thus, the point at which the V̅CO₂ curve exceeds the V̅O₂ curve is the V̅O₂ at which the AT is reached
- Training can improve V̅O₂ max
- Peak V̅O₂ < 20 ml/kg/min is associated with a poorer outcome
- Peak V̅O₂ is usually taken as the V̅O₂ when the patient stops
- An AT of at least 11ml/kg/min is required to safely conduct major surgery
- Contraindications
- Absolute
- MI 3-5/7 ago
- Unstable angina
- Syncope
- Endocarditis
- Ucontrolled CCF
- Dissection
- Respiratory failure
- Active infection
- Relative
- Severe LAD disease
- Moderate stenosis valvular disease
- High degree AV block
- Significant PAH
- Electrolyte abnormalities
- CEACCP
Link:ceaccp.oxfordjournals.org/content/10/2/33.full.pdf