K. P. O'Hagan

Effect of an abdominal binder during wheelchair exercise.

The purpose of this study was to determine whether use of an abdominal binder would affect oxygen uptake, trunk range of motion, and duration of the stroke phase during wheelchair propulsion. The subjects were six paraplegic wheelchair athletes with T1-T6 injuries and no abdominal muscle function. Each subject performed two trials, one while wearing the binder and one without the binder. Each trial consisted of submaximal and maximal exercise tests conducted on wheelchair rollers. Oxygen uptake was determined by open circuit spirometry while heart rate was determined by telemetry. Max VO2 values averaged 2.51 l.min-1 while average maximum heart rate values were 190 b.min-1. A 3-D video-based motion analysis system was used to obtain kinematic parameters of wheelchair propulsion. In general, 30% of the cycle time was comprised of the stroke phase, while 70% was comprised of the recovery phase across speeds. There were no statistically significant effects of the abdominal binder on any of the cardiovascular or kinematic variables at submaximal or maximal levels of exercise. Under the conditions of this laboratory investigation, it appears that an abdominal binder does not alter physiological or selected biomechanical measures in highly trained athletes.

Respiratory alterations with intrapericardial procaine in the conscious rabbit

1 Intrapericardial procaine, used to produce cardiac nerve blockade in both conscious and anaesthetized animals, has been reported to also produce changes in respiration. This study systematically investigated the effects of two doses of intrapericardial procaine on respiration in the conscious rabbit. 2 Rabbits were pre‐instrumented with a chronic diaphragm electromyogram (dEMG) recording electrode and intrapericardial catheter. Arterial pressure, heart rate, dEMG and respiratory excursions (recorded with a pneumograph) were monitored in the conscious rabbit before and after intrapericardial and intravenous infusion of 2 and 5% procaine. Efficacy of cardiac nerve blockade was tested by intravenous infusion of phenyl biguanide. Arterial blood gases were determined at rest and during changes in respiration. 3 Following a low dose of intrapericardial procaine (12 mg), dEMG and respiratory excursions increased (65 ± 13 and 65 ± 13%, respectively) with no change in breathing frequency or arterial blood gases. Following a high dose of intrapericardial procaine (30 mg), four of six animals exhibited a similar response. However, four of the six rabbits also exhibited a second type of response pattern characterized by a further increase in respiratory efforts (65 ± 13%), abolition of dEMG, and a mild hypoxaemia. 4 Intravenous infusion of a low dose of procaine was without effect, whereas intravenous infusion of a high dose of procaine produced minor behavioural responses. 5 In four additional anaesthetized rabbits, it was demonstrated that high doses of intrapericardial procaine anaesthetized the phrenic nerve to produce the observed alterations in respiration. 6 We conclude that if intrapericardial procaine is used to block cardiac nerves in conscious rabbits, it should be used in a low concentration and at the lowest possible total dose to avoid complications due to changes in respiration.