Blood Pressure and Electrocardiographic changes During Face Immersion in Water in Young Men on Regular Exercise
The cardiovascular responses in non-exercising and regularly exercising young men (22.0-32.0 yr) to breath-holding and face immersion in water at 210C or 400C is reported. The possibility of a myocardial oxygen conserving effect of face immersion in water is also investigated. Blood Pressure (BP) and electrocardiographic (ECG) measurements were made at the same time with the subject standing, neck flexed and immersed in water with the breath held. Results show that in both groups of subjects face immersion in water (at either temperature) with breath-hold significantly increased BP, QRS amplitude, PR interval, QT interval and R-R interval. Face immersion thus caused a significant reduction in heart rate (HR). However, in both groups of subjects, the changes in BP and HR due to face immersion at 210C were greater than the changes brought about by face immersion at 400C. The rate-pressure product (RPP) or myocardial oxygen demand fell by the same amount in the two groups of subjects at 400C. At 210C, the fall in myocardial oxygen demand was significantly greater in exercising subjects than in non-exercising subjects (p<0.001). The fall in myocardial oxygen demand at 210C in exercising subjects was also greater than the fall at 400C in both groups of subjects (p<0.001 respectively). The myocardial oxygen conserving effect seen during face immersion in this study is brought about by the observed bradycardia, which overrides the increase in blood pressure.
NQJHM Vol. 16 (1) 2005: pp. 1-5