Abstract
BackgroundWe evaluated the feasibility of an augmented robotics-assisted tilt table (RATT) for incremental cardiopulmonary exercise testing (CPET) and exercise training in dependent-ambulatory stroke patients.MethodsStroke patients (Functional Ambulation Category ≤ 3) underwent familiarization, an incremental exercise test (IET) and a constant load test (CLT) on separate days. A RATT equipped with force sensors in the thigh cuffs, a work rate estimation algorithm and real-time visual feedback to guide the exercise work rate was used. Feasibility assessment considered technical feasibility, patient tolerability, and cardiopulmonary responsiveness.ResultsEight patients (4 female) aged 58.3 ± 9.2 years (mean ± SD) were recruited and all completed the study. For IETs, peak oxygen uptake (V'O2peak), peak heart rate (HRpeak) and peak work rate (WRpeak) were 11.9 ± 4.0 ml/kg/min (45 % of predicted V'O2max), 117 ± 32 beats/min (72 % of predicted HRmax) and 22.5 ± 13.0 W, respectively. Peak ratings of perceived exertion (RPE) were on the range "hard" to "very hard". All 8 patients reached their limit of functional capacity in terms of either their cardiopulmonary or neuromuscular performance.A ventilatory threshold (VT) was identified in 7 patients and a respiratory compensation point (RCP) in 6 patients: mean V'O2 at VT and RCP was 8.9 and 10.7 ml/kg/min, respectively, which represent 75 % (VT) and 85 % (RCP) of mean V'O2peak. Incremental CPET provided sufficient information to satisfy the responsiveness criteria and identification of key outcomes in all 8 patients.For CLTs, mean steady-state V'O2 was 6.9 ml/kg/min (49 % of V'O2 reserve), mean HR was 90 beats/min (56 % of HRmax), RPEs were > 2, and all patients maintained the active work rate for 10 min: these values meet recommended intensity levels for bouts of training.ConclusionsThe augmented RATT is deemed feasible for incremental cardiopulmonary exercise testing and exercise training in dependent-ambulatory stroke patients: the approach was found to be technically implementable, acceptable to the patients, and it showed substantial cardiopulmonary responsiveness. This work has clinical implications for patients with severe disability who otherwise are not able to be tested.
Highlights
We evaluated the feasibility of an augmented robotics-assisted tilt table (RATT) for incremental cardiopulmonary exercise testing (CPET) and exercise training in dependent-ambulatory stroke patients
Cardiopulmonary fitness is compromised in stroke patients: their peak oxygen uptake (V'O2peak) ranges from 8–22 mL/kg/min, which corresponds to approximately half of age and gender matched healthy controls [1, 2]
A recent joint statement from the American Heart Association and the American Stroke Association recommends that stroke patients should undergo cardiopulmonary exercise testing (CPET) [4]
Summary
We evaluated the feasibility of an augmented robotics-assisted tilt table (RATT) for incremental cardiopulmonary exercise testing (CPET) and exercise training in dependent-ambulatory stroke patients. Cardiopulmonary fitness is compromised in stroke patients: their peak oxygen uptake (V'O2peak) ranges from 8–22 mL/kg/min, which corresponds to approximately half of age and gender matched healthy controls [1, 2]. The low V'O2peak limits patients' ability to live independently [3] and hinders participation in rehabilitation and exercise programmes [4]. Low cardiopulmonary fitness can further heighten the existing risk for cardiovascular disease [5] by predisposing patients to a sedentary lifestyle because of activity limitation and early fatigue [6]. Impairments following stroke such as weakness, ataxia or spasticity can preclude some patients from exercise testing on standard devices. Semi-recumbent cycle ergometers and total-body recumbent steppers have hitherto been used as alternatives to standard treadmills and cycle ergometers in order to test patients with balance and coordination problems [4]
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