Safety and feasibility of a functional electrical stimulation cycling-based muscular dysfunction diagnostic method in mechanically ventilated patients.

BACKGROUND: A nonvolitional diagnostic method based on FES-Cycling technology has recently been demonstrated for mechanically ventilated patients. This method presents good sensitivity and specificity for detecting muscle dysfunction and survival prognosis, even in unconscious patients. As the clinical relevance of this method has already been reported, we aimed to evaluate its safety and feasibility. METHODS: An observational prospective study was carried out with 20 critically ill, mechanically ventilated patients. The FES-cycling equipment was set in a specific diagnostic mode. For safety determination, hemodynamic parameters and peripheral oxygen saturation were measured before and immediately after the diagnostic protocol, as well as venous oxygen saturation and blood lactate. The creatine phosphokinase level (CPK) was measured before and 24, 48, and 72 h after the test. The time taken to carry out the entire diagnostic protocol and the number of patients with visible muscle contraction (capacity of perceptive muscular recruitment) were recorded to assess feasibility. RESULTS: Heart rate [91 ± 23 vs. 94 ± 23 bpm (p = 0.0837)], systolic [122 ± 19 vs. 124 ± 19 mm Hg (p = 0.4261)] and diastolic blood pressure [68 ± 13 vs. 70 ± 15 mm Hg (p = 0.3462)], and peripheral [98 (96-99) vs. 98 (95-99) % (p = 0.6353)] and venous oxygen saturation [71 ± 14 vs. 69 ± 14% (p = 0.1317)] did not change after the diagnostic protocol. Moreover, blood lactate [1.48 ± 0.65 vs. 1.53 ± 0.71 mmol/L (p = 0.2320)] did not change. CPK did not change up to 72 h after the test [99 (59-422) vs. 125 (66-674) (p = 0.2799) vs. 161 (66-352) (p > 0.999) vs. 100 (33-409) (p = 0.5901)]. The time taken to perform the diagnostic assessment was 11.3 ± 1.1 min. In addition, 75% of the patients presented very visible muscle contractions, and 25% of them presented barely visible muscle contractions. CONCLUSIONS: The FES cycling-based muscular dysfunction diagnostic method is safe and feasible. Hemodynamic parameters, peripheral oxygen saturation, venous oxygen saturation, and blood lactate did not change after the diagnostic protocol. The muscle damage marker (CPK) did not increase up to 72 h after the diagnostic protocol.

Metabolic, ventilatory and cardiovascular responses to FES-cycling: A comparison to NMES and passive cycling.

BACKGROUND: Cyclergometry with functional electrical stimulation (FES-cycling) is a feasible method for rehabilitation. The concept is to promote exercise induced by depolarization of the motoneuron and muscular contraction. OBJECTIVE: To measure acute physiological responses to FES-cycling. METHODS: Retrospective study of data from ten healthy volunteers who performed FES-cycling, passive cycling and neuromuscular electrical stimulation (NMES) alone. Metabolic, ventilatory and cardiovascular parameters were analyzed. RESULTS: Oxygen uptake enhanced 97 ± 15% during FES-cycling, with medium effect size compared to NMES and large effect size compared to passive cycling. Energy expenditure enhanced 102 ± 15% during FES-cycling, with medium effect size compared to NMES and large effect size compared to passive cycling. Minute ventilation enhanced 115 ± 26% during FES-cycling, with small effect size compared to NMES and medium effect size compared to passive cycling. Cardiac output enhanced 21 ± 4% during FES-cycling, with medium effect size compared to NMES and passive cycling. Arterial - mixed venous oxygen content difference enhanced 60 ± 8% during FES-cycling, with a medium effect size compared to NMES and large effect size compared to passive cycling. CONCLUSIONS: FES-cycling enhances metabolic, ventilatory and cardiovascular demands and the physiological responses are higher than NMES and passive cycling.