Evaluation of the Ventilatory Effects of a Restraint Chair on Human Subjects

Background: Combative individuals often require physical restraint in the prehospital and law enforcement setting. Specialized restraint chairs have been utilized for this purpose in the latter case, but concern has arisen that restrained individuals are at risk for ventilatory compromise and asphyxiation. Objective: We sought to determine if placement in a restraint chair results in alterations of respiratory or ventilatory function. Methods: We conducted a randomized, cross-over, controlled experimental trial in 10 healthy human volunteers performed at a university exercise physiology laboratory. After exercise on a cycle ergometer to 85% of the age-predicted maximal heart rate, subjects were randomized to either a sitting position or restraint chair with arms, legs, and chest secured using standard law enforcement protocol. Subjects remained in each position for 30 min, during which pulmonary function testing of maximal voluntary ventilation (MVV) was performed at 11 and 30 min. Arterial oxygen saturation (O2sat) and end-tidal PCO2 levels (PETCO2) were monitored continuously. Subjects repeated the experimental trial in the alternate position after a 45-min rest period. Measures between restraint and sitting positions were compared using a paired t-test at each time measurement. Results: There was no evidence of hypoxemia. Mean PETCO2 levels were not statistically different between the two groups at any time (p > 0.05), and there was no evidence of hypercapnia. Conclusion: In healthy subjects, placement in a restraint chair resulted in a small decrease in MVV, but did not result in any changes in O2sat or PETCO2.