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EXSU 610 > Performance-based measures > Flashcards

Performance-based measures Flashcards

1
Q

What does the assessment of functional capacity reflect?

A

The assessment of functional capacity reflects the ability to perform activities of daily living that require sustained aerobic metabolism.

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2
Q

How is functional capacity assessment “integrated” in nature?

A

It involves the integrated efforts and health of the pulmonary, cardiovascular, and skeletal muscle systems (global) dictate an individual’s functional capacity

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3
Q

Why is functional/aerobic capacity important to sustain surgery?

A

The metabolic demand (d/t tissue injury, inflammatory response and neuroendocrine response) required for surgery must be met to sustain surgery and avoid complications. Pt must be able to send oxygen to tissues.

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4
Q

Name 4 non-modifiable predictor factors of surgical risk.

A
  • Type of surgery
  • Surgical setting
  • Age
  • Co-morbidities
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5
Q

Name 7 modifiable risk factors for low functional capacity (–> surgical risk)

A
  • Frailty/Sarcopenia
  • Low PA
  • Cardiorespiratory reserve
  • Smoking/alcohol
  • Nutritional status
  • Anemia
  • Emotional status
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6
Q

Name 5 outcomes related to surgery that can be predicted from preop functional capacity.

A
  1. Post-operative morbidity (complications) and mortality
  2. Length of stay
  3. Recovery time
  4. Quality of life
  5. Degree of dependence
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7
Q

What needs to occur for “exercise intolerance” to happen? Why is it important in the surgical context?

A

Exercise intolerance happens when energy demand (ATP) is no longer met by supply (ventilation, cardiac output and/or skeletal muscle blood flow).
In the peri-operative context, the metabolic demand created by the surgical stress response requires increased tissue oxygen delivery which must be matched by increased supply, if failure of tissue perfusion and oxygenation are to be avoided.
o If not supplied enough, tissue oxygenation will not be done well after surgery

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8
Q

What is the role of CPET prior to surgery?

A

The goal of CPET is to stress the involved organ systems with progressive exercise to a level at which response abnormality becomes discernible in order to:
o Discriminate an abnormal magnitude or pattern of response (compared with the age-, gender- and activity-matched standard subject) of appropriately selected variables
o Match the magnitude or pattern of abnormality with that characteristic of particular impairments of physiological system function

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9
Q

Explain how CPET is an integrative measure.

A

It is a global assessment of the integrated responses of the pulmonary, cardiovascular and metabolic systems that are not adequately reflected through measurement of individual organ system function.

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10
Q

Explain how CPET is a dynamic measure.

A

Resting pulmonary and cardiac function testing cannot reliably predict exercise performance and functional capacity. Overall health status correlates better with exercise tolerance rather than with resting measures. Thus CPET gives information about physiological reserve.

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11
Q

Explain how CPET is an objective measure.

A

It reflects functional function. Patients self-reported exercise capacity is often inaccurate

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12
Q

Explain why the CPET is useful in surgery.

A
  • Establishing the exercise capacity and the limits of physiological system function during exercise.
  • Evaluating the normalcy of exercise responses
  • Identifying the cause(s) of exercise intolerance (muscle, heart, or lungs?)
  • “Triggering” an abnormality (e.g. exercise-induced asthma)
  • Stratifying surgical risk, with the potential utility to guide decisions relating to surgery and peri-operative care
  • Providing a frame of reference for change with respect to therapeutic interventions (e.g. pharmacological, O2 supplementation, surgical) or training
  • Establishing prognostic outcomes
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13
Q

Name the 4 phases of a CPET test and their duration.

A
  1. Baseline (2-3 min) - recording with no exercise
  2. Free-wheel (1-3 min) - Warmup, getting used to the cadence of the test
  3. Exercise phase (8-12 min) - Ramp determined based on height, weight, sex and age, watts increase with time - and patients continue until they reach their max effort.
  4. Recovery phase (2-5 min)
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14
Q

What is the cadence of a CPET test?

A

65 rpm

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15
Q

Name all equipment needed for a CPET

A
  • Treadmill, cycle-ergometer, etc.
  • Metabolic cart with flow and gas analyzer (CO2, O2)
  • ECG, BP, SpO2
  • Perceived exertion and dyspnea scales (Modified Borg scale (RPE))
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16
Q

Define VO2max and VO2peak.

A
  • VO2max represents the maximal achievable level of oxidative metabolism. (gold standard for aerobic capacity).
  • VO2 peak is defined as the highest oxygen uptake at end-exercise. As such, it is reflective of the patient’s “best effort”
17
Q

Name 4 potential factors limiting VO2 max

A
  1. Pulmonary diffusing capacity
  2. Cardiac output
  3. O2 carrying capacity
  4. Skeletal muscles
18
Q

Describe the relationship between ventilation and VO2 and VCO2

A
  • Ventilation regulates acid-base status.
  • Ventilation and VCO2 have a linear relationship
  • Ventilation and VO2 have a linear relationship until the anaerobic threshold is reached
19
Q

What is the anaerobic threshold?

A

• The AT is a metabolic rate and is defined as the O2 consumption (V𝑂2) above which arterial [lactate] first begins to increase systematically during incremental exercise reflecting increased glycolysis.
o At some point in exercise, the aerobic metabolism is not enough to sustain the exercise and demand in energy. –> Anaerobic metabolism kicks in
• It is expressed in ml/kg/min or ml/min or as a percentage of the predicted value of VO2max (50-60% VO2max).

20
Q

Explain the 3-criterion method of the anaerobic threshold.

A
  • Modified V slope (VO2 to VCO2)
  • Hyperventilation relative to oxygen
  • No hyperventilation relative to CO2
21
Q

What is VE/VCO2 and what does it indicate? What can this value predict?

A

• 𝑉𝐸/𝑉𝐶𝑂2 gives insight into the efficiency of ventilation-perfusion matching in the lung and the efficiency of gas exchange.
It is associated with morbidity and mortality in surgical cohorts.

22
Q

What is a normal VE/VCO2 value, and what do impairments indicate?

A

A normal value is around 25-30 and increases in the ratio reflect impairment of V/Q, either from respiratory causes or from impaired cardiac function. In heart failure patients a value for VE/VCO2 greater than 34 is associated with a poor prognosis, particularly when combined with an AT less than 11 ml/kg

23
Q

What is VE/VO2 and what does it indicate?

A

liters of ventilation per liter of oxygen consumed. The normal value is typically around 25-30 and increases once the person reaches their ventilatory threshold. High values are a marker of inefficient ventilation, which can be due to hyperventilation or increased dead-space, a marker of poor gas exchange.

24
Q

What is the O2 pulse and what does it indicate?

A

Volume of oxygen taken up by the pulmonary blood per heartbeat.
O2 pulse= VO2/HR (ml O2/beat).
It is a surrogate measure of stroke volume, as the arterial-mixed venous oxygen difference [C(a-v)O2], reaches
a steady state at maximal exercise. The normal value depends on the size of the subject but can range between 8 and 18 ml O2/heartbeat.

25
Q

What is the cutoff for anaerobic threshold with CPET that predicts survival? Postop complications?

A

11 for survival (9 in liver transplant patients), 10 for complications and LOS

26
Q

Explain the VO2max cutoffs for complication risks (Chest, 2009)

A

VO2max > 20 ml/kg/min = minimal risk
VO2max < 15 ml/kg/min = increases complications
VO2max < 10 ml/kg/min = very high risk of postop complications

27
Q

In clinical settings, which CPET values are currently used to classify high-risk surgical patients?

A

a. AT < 10 -11ml/kg/min

b. VO2peak < 15ml/kg/min

28
Q

Name absolute contraindications to CPET.

A 
Acute myocardial infarction
Unstable angina
Uncontrolled arrhythmia causing symptoms or hemodynamic instability
Syncope
Active endocarditis
Acute myocarditis or pericarditis
HF (uncontrolled)
Uncontrolled asthma
etc...
29
Q

Name relative contraindications to CPET.

A 
Untreated left main coronary stenosis
Asymptomatic severe aortic stenosis
Severe untreated arterial HTN at rest (>200/120)
Tachyarrhythmia or brady-
hypertrophic cardiomyopathy
Abdominal aortic aneurysm > 8cm
electrolyte abnormalities
Advanced or complicated pregnancy
...
30
Q

Name 2 examples of tests that can be performed to reflect CPET, without CPET.

A

6MWT

STST

31
Q

What can 6MWT results predict in terms of post-op?

A
  • Use to assess treatment response and predict morbidity and mortality in chronic respiratory diseases.
  • Predicts postoperative recovery in colorectal sx
  • Predicts mortality in lung and liver transplant
32
Q

What can 6MWT results predict in terms of pre-op?

A

• Could be used as a screening tool to identify high risk patients with reduced functional capacity that need further evaluation

33
Q

Which 6MWT value correlates with which CPET value? Why is this cutoff important?

A 
•	Correlation between 6MWT and CPET --> 390-400m = VO2max 15 mL/kg/min
These values are linked to:
o	Post-op morbidity and mortality
o	CVD
o	Mobility limitation
o	Disability
34
Q

What is a significant meaningful difference for 6MWT?

A

20m (“clinical improvement”)

Equivalent to 2mL/kg/min CPET improvement

35
Q

Name absolute contraindications for 6MWT.

A 
acute endocarditis
Acute MI
Unstable angina
Uncontrolled arrhythmia
syncope
uncontrolled HF
Thrombosis of lower extremities
Pulmonary edema
Acute resp failure
Uncontrolled asthma
...
36
Q

What does STST measure?

A
  • Influenced by poor balance: good tool to assess risk of falls in the elderly
  • Good tool to measure frailty
37
Q

Name multiple STST variations.

A
  • 5 repetition sit-to-stand
  • 10 repetition sit-to-stand
  • 30-second sit-to-stand (used in prehab)
  • 1-minute sit-to-stand
  • 5-minute sit-to-stand
38
Q

What is the 30-sec STST value that reflects low functional capacity?

A

Varies by age and gender.

Varies from 14 (60-64 male) to 4 (90-94 female).

39
Q

What does CPET stand for?

A

Cardiopulmonary exercise testing

EXSU 610 (7 decks)

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