In tetraplegic patients, immersion to shoulder level in isothermic water increased the SVC nearly 25% above basal measurements. However, a healthy control group showed the opposite pattern with an average reduction of 4%. Among the tetraplegic patients, the lower the preimmersion vital capacity, the greater was the percentage of improvement following immersion.
Only two prior investigations have studied the effect of immersion on the pulmonary function of subjects with tetraplegia, and agree with and complement the results of present study. In 1982, Jaeger-Denavit et al evaluated 12 tetraplegic subjects immersed in water (29 to 31°C) with “head out” and showed an elevation of vital capacity, accompanied by a fall in residual volume. In 1991, this reduction in residual volume was confirmed by Bosch and Wells in eight tetraplegic subjects immersed to the “neck” in water at 34°C. Neither study mentions the time of immersion. In spite of these similar results, the studies were conducted in different experimental conditions without considering the potential effect of water temperature and time of immersion on the results.