Feasibility of cardiopulmonary exercise testing and training using a robotics-assisted tilt table in dependent-ambulatory stroke patients

Saengsuwan, Jittima; Huber, Celine; Schreiber, Jonathan; Schuster-Amft,
Corina; Nef, Tobias; Hunt, Kenneth.

Journal of NeuroEngineering and Rehabilitation, December 2015, Vol. 12 Issue: Number 1 p1-10, 10p;

Abstract: 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.   Stroke 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.  Eight 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’O2at 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’O2was
6.9 ml/kg/min (49 % of V’O2reserve), 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.  The 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.