Exersize Capacity Flashcards
What is essential for efficient gas exchange?
Maximum coupling between ventilation & perfusion.
Inadequacy in either of these will have a significant impact on the removal of CO2 & blood oxygenation.
What would happen if Alveoli were not well ventilated?
Pulmonary circulation has specialized cells that can detect local Oxygen concentration, low O will cause to vasoconstriction allowing blood to go elsewhere in the lungs.
How do we evaluate exercise capacity in a clinical environment?
Cardiopulmonary exercise test
Six-minute walk test
Incremental shuttle walk test
What is involved in a Cardiopulmonary exercise test?
Uses a cycle ergometer or treadmill
Intensity is incremental
Undertaken under close clinical supervision in a controlled environment
ECG, ventilation, O2 and CO2 routinely measured
What are the outputs of a Cardiopulmonary exercise test?
Lots and lots of data
Peak VO2 usually the primary outcome
ECG changes monitored throughout
What are the advantages of a Cardiopulmonary exercise test?
Quantifies performance in relation to metabolism
Precise and reproducible
Continuous monitoring for safety
What are the disadvantages of a Cardiopulmonary test?
Requires skilled technical support (calibration and
Very expensive (initial & ongoing costs)
Needs dedicated space
What is involved in a Six-minute walk test?
Uses a 20-30 m flat course (e.g. corridor)
Objective is to cover greatest distance as possible in six minutes
Externally timed by assessor
Sub-maximal test
What are the outputs of a Six-minute walk test?
Primary outcome is total distance walked in six minutes
Secondary variables may be ‘perceived exertion’ scales, heart rate and pulse oximetry
What are the advantages of the Six-minute walk test?
Patient-driven pace – speeding up, slowing down & rest OK
Cheap to deploy
Validated in many clinical populations
What are the disadvantages of the Six-minute walk test?
Requires a significant unobstructed course, it often undertaken in a public hospital corridor
The pace is not reregulated
What is involved in the incremental shuttle walk test?
Uses a 10 m circuit
Externally paced by an audio recording (like bleep test)
Each minute has one extra length than the previous minute (e.g. minute 1 = 3 lengths of 20s; minute 2 = 4 lengths of 15s)
What are the outputs of the incremental shuttle walk test?
Primary outcome is total distance walked before volitional end
Secondary variables may be ‘perceived exertion’ scales, heart rate and pulse oximetry
What are the disadvantages of the incremental shuttle walk test?
Requires an unobstructed course, it is often undertaken in a public hospital corridor
For some the incremental nature is difficult (min. speed 1.8km/hour)
Ceiling effect of 1020 m
Patient can be penalised for poor pace management
What are the advantages of the incremental shuttle walk test?
Cheap to deploy
Validated in many clinical populations
The external pacing helps some to achieve maximum levels
