Cardioresp - Exercise Capacity Flashcards
What is physical activity
A holistic term for all muscular activity of all intensity
What is exercise
Structured, purposeful activity that improves gross muscular activity to improve physical condition
What are ADLs
Basic independent self-care tasks done on a day to day basis that require strength, coordination and range of motion
What factors affect exercise capacity in the airway
Inspired O2
Airway resistance/calibre
Pulmonary compliance and elastance
Diffusion distance from alveoli to the capillaries
What factors affect exercise capacity in the heart
Valve structure Myocardial contractility Myocardial thickness Myocardial perfusion Conduction system
What factors affect exercise capacity in the blood
Blood parameters e.g. MCV, HCT, Hb
Arterial blood pressure
Blood viscosity
Perfusion
What factors affect exercise capacity in the muscles
Capillary density
Mitochondrial density
Local vasodilation
Oxidative enzyme concentration
What is V/Q matching
Ventilation perfusion matching - alveoli that are not well ventilated undergo vasoconstriction as blood can be directed elsewhere where there is a greater rate of gas exchange, therefore a greater demand for increased blood flow.
Where is perfusion greatest
At the base of the lungs due to the gravity of intravascular pressure moving downwards
Where is ventilation greatest
At the base of the lungs due to a less negative intrapleural pressure therefore a lower trasnpulmonary pressure. This means that alveoli at the base are smaller due to a greater level of compliance and thus more ventilation
What 3 tests can we use to evaluate exercise
Cardiopulmonary exercise test
6 minute walk test
Incremental shuttle walk test
What’s involved in cardiopulmonary exercise test
Cycle ergometer or treadmill with incrementally increasing intensity.
We measure ECG, O2, Co2 and ventilation
What’s involved in six minute walk test
You walk a 20-30 metre flat course such as a corridor over 6 minutes, and the max distance you walk is recorded
What’s involved in incremental shuttle walk test
10 metre circuit that’s regulated by external audio - every minute you do a certain number of laps, the number of laps increases every minute (like a bleep test)
What are the outputs of a cardiopulmonary exercise test
ECG continually recorded - however we are most interested in peak VO2
What are the outputs of a six minute walk test
Distance walked, we may also measure heart rate, pulse oximetry and perceived exertion e.g. with Borg’s RPE scale (Rating of Perceived exertion)
What are the outputs of a incremental shuttle walk test
Total distance walked before volitional end - we may also measure heart rate, pulse oximetry and perceived exertion e.g. with Borg’s RPE scale (Rating of Perceived exertion)
What are the pros of a cardiopulmonary exercise test
- Quantifies performance in relation to metabolism
- Precise and reproducible
- Continuous monitoring for safety
What are the pros of a six minute walk test
- Patient driven pace
- Cheap
- Validated in most clinical populations
What are the pros of a incremental shuttle walk test
- Cheap
- Validated clinically
- Can help achieve maximum levels due to external audio
What are the cons of a cardiopulmonary exercise test
- Requires skill/support
- Very expensive
- Needs dedicated space
What are the cons of a six minute walk test
- Needs unobstructed course therefore hard to do in hospital
- Pace is not regulated
What are the cons of a incremental shuttle walk test
- Needs unobstructed course
- Minimum pace = 1.8 km/hr therefore may be hard for some
- Ceiling effect = 1020 m
- Patient may be penalised for poor pace management therefore results may be skewed unnecessarily
What is MVV
Maximum voluntary ventilation
What is PET Co2/O2
End tidal partial pressure of Co2/O2
What is HF
Heart frequency
What is SpO2
Peripheral oxygen saturation
What does a low rate of oxygen consumption indicate
There may be a problem in oxygen transport or excitatory impairment
What is RER and how is it calculated
Respiratory exchange ratio - calculated by dividing VCO2 by VO2 - therefore the higher RER means the more reliant we are on anaerobic respiration
How do we indicate the index of anaerobic metabolism
We can use a graph to see the different gradients of O2 and CO2 - when the gradients change so that CO2 starts to overtake O2 - we know that we’re becoming more anaerobic. This is because O2 coming in should be a surplus of CO2 going out
