Evaluating Exercise Capacity Flashcards
what is the difference between exercise, physical activity and activities of daily living?
exercise= purposeful, structured activity that involves gross muscular activity to improve physical condition
physical activity= holistic term that includes all muscular activities of all intensities
AODL= basic independent self-care tasks done on a daily basis that require coordination, strength and range of motion
what factors affect the capacity to exercise within the body?
what can exercise limitations be caused by?
deficits in several systems
- Neurological
- Motor control, coordination
- Respiratory
- Ability lung ventilate, pulmonary perfusion, gas exchange between lungs and blood
- Cardiovascular
- Ability heart to receive blood from lungs and pump muscles
- Muscular
- Local perfusion, muscle cell enzymes
what is affected when there is a ventilation-perfusion mismatch?
impact removal CO2 and oxygenation
efficient gas exchange needs maximum V/Q coupling
what changes in lungs when there is less ventilation?
Ppl is more negative
greater transmural pressure gradient
alveoli larger + less complient
what happens in the lungs when there is more ventilation?
Ppl is less negative
smaller transmural pressure gradient
alveolar small & more compliant
what happens when there is a lower perfusion flow rate?
lower intravascular pressure
less recruitment
greater resistance
what happens when there is a higher perfusion flow rate?
higher intravascular pressure
more recruitment
less resistance
where are ventilation and perfusion greatest?
at base of lungs
where is V/Q lowest?
at base of lungs
what are the tests used to evaluate exercise capacity?
cardiopulmonary exercise test
6-minute walk test
incremental shuttle walk test
what is the cardiopulmonary exercise test?
- Uses cycle ergometer or treadmill
- Intensity incremental
- Undertake under clinical supervision
- ECG, ventilation, O2 and CO2 measured routinely
what are the outputs of the cardiopulmonary exercise test?
Peak VO2 primary outcome
ECG changes monitored
what are the advantages of the cardiopulmonary exercise test?
- Quantifies performance in relation to metabolism
- Precise and reproducible
- Continuous monitoring for safety
what are the disadvantages of the cardiopulmonary exercise test?
- Requires skilled technical support
- Very expensive
- Needs dedicated space
what is the 6-minute walk test?
- 20-30m flat course
- Objective to cover greatest distance as possible in 6 minutes
- Externally timed by assessor
- Sub-maximal test
what are the outputs of the 6-minute walk test?
- Primary outcome is total distance walked in 6 minutes
- Secondary variables
- Perceived exertion scales, Heart rate, Pulse oximetry
what are the advantages of the 6 minute walk test?
- Patient-driven pace
- Cheap to deploy
- Validated in many clinical populations
what are the disadvantages of the 6 minute walk test?
- Requires significant unobstructed course
- Pace is not regulated
what is the incremental shuttle walk?
10m circuit
externally paced by audio recording
each minute has one extra length than previous minute
what are the outputs of the incremental shuttle walk test?
primary= total distance walked before volitional end
secondary= perceived exertion scales, heart rate and pulse oximetry
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
what are the disadvantages of the incremental shuttle walk test?
- Requires unobstructed course
- For some incremental nature is difficult
- Ceiling effect of 1020m
- Patient can be penalised for poor pace management
what is used to calculate degree of breathlessness?
MRC dyspnoea scale
how can exercise testing be used in clinical populations?
- Exercise tests can be used to monitor disease severity/ progression and response to treatment
- An assessment for ambulatory oxygen could be carried out using 6MWT
- If patient is stable pulmonary rehabilitation may be prescribed to increase exercise capacity
what is required to prescribe long term oxygen therapy (LTOT)?
use >15 hours/day
this would include measure of blood gasses
