Evaluating Exercise Capacity Tutorial Flashcards
Define exercise:
Define physical activity:
Define activities of daily living:
Exercise = intent (purposeful) + movement: Purposeful, structured activity that involves gross muscular activity to improve physical condition
Physical Activity = movement: A holistic term that includes all (purposeful and incidental) muscular activity of all intensities
Activities of daily living = movements associated with day to day basic self-care tasks that require co-ordination i.e. ability to feed yourself, ability to take care of personal hygiene, ability to go to the bathroom
What are all the factors that are associated with delivery of oxygen to tissues to meet demand during exertion?
Cardiovascular:
Increase in cardiac output
Increase in heart rate - sympathetic nervous activity
Increase in stroke volume
Redirection of blood to muscles - increase in BP allows for balance of vasoconstriction and vasodilation
Respiratory:
Increase in breathing rate - increase in CO2 causes respiratory neurons in the brainstem to fire more often
Increase in breathing depth - to minimise percentage of air breathed in that is lost to deadspace
Decreased diffusion distance for gas exchange - alveoli stretch bigger when breathing deeper putting in closer to the capillaries
Musculoskeletal:
Vasodilation in the muscles
Muscle contraction increases venous return, which increases stroke volume
Use of myoglobin
What is ventilation perfusion matching?
So what is ventilation perfusion mis-matching?
Efficient gas exchange needs maximum coupling between ventilation and perfusion - so both must be increased to increase oxygen delivery
Ventilation perfusion mis-matching i.e. when you get one but not the other and that limits oxygen delivery
e. g. having mucus take up space in the lung prevents increase of ventilation
e. g. having a blood clot that prevents increase in perfusion
What is the cardiopulmonary exercise test?
Use cycle ergometer or treadmill
Intensity is incremental
Undertaken under close clinical supervision in a controlled env.
ECG, ventilation, O2 and CO2 routinely measured
Lots and lots of data
Peak VO2 usually the primary outcome
ECG changes monitored throughout
What are the advantages and disadvantages of the cardiopulmonary exercise test?
Adv:
Quantifies performance in relation to metabolism
Precise and reproducible
Continuous monitoring for safety
Disadv:
Requires skilled technical support (calibration and
Very expensive (initial & ongoing costs)
Needs dedicated space
What is the six minute walk test?
Uses 20-30m flat course
Objective is to cover greatest distance as posibile in 6 minutes
Externally timed by assessor
Sub-maximal test
Primary outcome is total distance walked in six minutes
Secondary variables may be ‘perceived exertion’ scales, HR and pulse oximetry
What are the advantages and disadvantages of the six minute walk test?
Adv: Predictive of mortality Patient-driven pace – speeding up, slowing down & rest OK Cheap to deploy Validated in many clinical populations
Disadv:
Doesn’t ask patients how they feel - perception of breathlessness
Doesn’t take into account how many stops / pauses the person had to take during the 6 min walk
Requires significant, unobstructed course, it is often undertaken in a public hospital corridor
The pace is not regulated
What is the incremental shuttle walk test?
Uses a 10m circuit
Externally paced by an audio recording (bleep test)
Each minute has one extra length than the previous minute
Primary outcome is total distance walked before volitional end
Secondary variables may be ‘perceived exertion’ scales, HR, and pulse oximetry
What are the advantages and disadvantages of the incremental shuttle walk test?
Adv: Predictive of mortality Cheap to deploy Validated in many clinical populations The external pacing helps some to achieve maximum levels
Disadv:
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
Case Study
80M - exacerbation of COPD
6 weeks = dramatic deterioration in resp function and needed oxygen at home for the first time
6 min walk test:
400-700m = normal
He got: 338m first time, 203m second time
Discuss the reasons for the reduction in exercise capacity in the second test result:
- Deterioration if the tests were done some time apart
2. If the tests were done one after the other, the first test could have affected the second test
What does he score on the MRC dysnopea scale?
Grade 4 - Stops for breath after walking 1000yards (900m), or after a few minutes on level ground
Grade 5 - Too breathless to leave the house, or breathless when dressing / undressing
Would you recommend pulmonary rehabilitation?
Anything above 15hrs of oxygen delivery = long term oxygen delivery
Ambulatory oxygen therapy - oxygen delivered when exercising
How does COPD affect breathlessness?
Hyperinflation of lungs - barrel chested
Increased residual volume as not enough air is breathed out
How does it feel to be breathless?
How does it feel to have air trapped in the lungs?
Like drowning
Hyperinflated lungs = feels like air trapped in the lungs = feels like if you constantly had to breath in as deeply as possible = v. uncomfortable
Does oxygen therapy improve breathlessness?
It improves how much oxygen diffuses into the RBCs
If CO2 is high and is driving the breathlessness, then the increased O2 in the air will not improve breathlessness
