This study aims to investigate how sepsis and critical illness can impair the cardiovascular system and microcirculation in intensive care unit (ICU) patients, which can lead to long-lasting muscle weakness/dysfunction or ICU-Acquired Weakness (ICU-AW) and exercise limitations.
This longitudinal study will assess cardiovascular fitness and microvascular function through two (2) follow-ups after ICU discharge: at (i) 6 months, and (ii) 12 months. The goal is to understand how microvascular dysfunction contributes to ICU-AW and long-term exercise limitation in ICU survivors. Specific goals are: 1. Evaluate peak oxygen uptake and oxygen on/off kinetics in ICU survivors using a standardized cardiopulmonary exercise test (CPET) protocol. 2. Characterize skeletal muscle microvascular function in ICU survivors using high-resolution NIRS during CPET protocol. 3. Determine the association between impairments in skeletal muscle microvascular oxygen delivery and cardiovascular blood flow regulation in ICU survivors.
Study Type
OBSERVATIONAL
Enrollment
50
Health Sciences Centre Winnipeg
Winnipeg, Manitoba, Canada
RECRUITINGVO2 peak oxygen uptake
Peak Oxygen uptake (VO2, mL/kg/min) will be measured during incremental exercise on a cycle ergometer during cardiopulmonary exercise testing (CPET).
Time frame: Tests will be conducted on up to two (2) different occasions after ICU discharge: (i) 6 months, and (ii) 12 months.
oxygen on/off kinetics
time constant (seconds) of oxygen uptake will be assessed at the transition to constant work rate exercise at the beginning of CPET; time constant (seconds) of oxygen uptake will also be assessed at the transition to rest at the end of CPET after reaching VO2 peak.
Time frame: Tests will be conducted on up to two (2) different occasions after ICU discharge: (i) 6 months, and (ii) 12 months.
NIRS deoxygenation during exercise (deoxy-hemoglobin)
NIRS will be applied to the vastus lateralis during exercise testing. Deoxygenation profile, as measured by increase in deoxy-hemoglobin will be recorded throughout exercise. Higher values indicate impaired oxygen delivery to tissue.
Time frame: Tests will be conducted on up to two (2) different occasions after ICU discharge: (i) 6 months, and (ii) 12 months.
NIRS deoxygenation during exercise (tissue saturation index)
NIRS will be applied to the vastus lateralis during exercise testing. Deoxygenation profile, as measured by decrease in tissue saturation index will be recorded throughout exercise. Lower values indicate impaired oxygen delivery to tissue.
Time frame: Tests will be conducted on up to two (2) different occasions after ICU discharge: (i) 6 months, and (ii) 12 months.
Functional Independence Measure (FIM) Questionnaire
will assess functional capacity, and will be administered by research staff. Response will be sought directly from the patient. FIM is scored with motor (13-91) and cognitive (5-35). Lower scores indicate lower functional independence
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Time frame: Questionnaire will be conducted on up to 2 (2) different occasions after ICU discharge: (i) 6 months, and (ii) 12 months.
Frailty Index
The frailty index identifies 42 deficits, each coded as 0 (absent), 1 (present), or 0.5 (where intermediate values were possible). It was calculated as the cumulative proportion of deficits present (minimum score 0; maximum score 1.0), and then graded as mild (0 and 0.2), moderate (0.2 and 0.4) or severe frailty (\>0.4). See references for studies where Index is derived.
Time frame: Tests will be conducted on up to two (2) different occasions after ICU discharge: (i) 6 months, and (ii) 12 months.
Medical Research Council (MRC) sum score
Medical Research Council (MRC) sum score tests power in muscle groups for upper and lower extremities and score is tallied as the sum of all tested muscles. Value ranges from complete paralysis (0/60) to full strength (60/60). Score less than 48/60 denotes clinically significant weakness.
Time frame: Tests will be conducted on up to two (2) different occasions after ICU discharge: (i) 6 months, and (ii) 12 months.
Anaerobic threshold
Work rate at anaerobic threshold (AT), represented at percentage of VO2 peak will be quantified with CPET. This corresponds to the time where oxygen (O2) utilization and carbon dioxide (CO2) production curves begin to diverge.
Time frame: Tests will be conducted on up to two (2) different occasions after ICU discharge: (i) 6 months, and (ii) 12 months.
Forced Vital Capacity (FVC)
Standard spirometry techniques are used to quantify the maximum volume of expired breath (Litres), and represented as a %predicted compared to reference values. All tests are performed in accordance with standard ATS guidelines.
Time frame: Tests will be conducted on up to two (2) different occasions after ICU discharge: (i) 6 months, and (ii) 12 months.
Forced Expiratory Volume at 1-second (FEV1)
Standard spirometry techniques are used to quantify the volume of expired breath (Litres) in 1 second, and represented as a %predicted compared to reference values. All tests are performed in accordance with standard ATS guidelines.
Time frame: Tests will be conducted on up to two (2) different occasions after ICU discharge: (i) 6 months, and (ii) 12 months.
Recruitment and retention
The number of completed sessions within 12 months for each eligible patient will be recorded.
Time frame: Ongoing throughout 12 months after ICU discharge