A practical method of differential hypothermia to permit use of a low pump oxygenator flow.

By cooling the blood just before returning it to the body, marked reduction in the temperature of the heart, brain, liver, and kidney can be produced easily and with great economy in heat transfer, since the great bulk of the animal or patient, consisting of skin, muscle, and bone, is cooled much more slowly. This results in a marked oxygen saving, due to the direct antimetabolic effect of the cooling. Metabolic acidosis can be avoided and so far no irreversible effects of the cooling have been discoverable. Warming is so greatly facilitated by the heat stored in the nonvital areas that it is not necessary to warm the blood returning from the extracorporeal circuit. The use of safe, low, extracorporeal flows offers a number of possible advantages including great simplicity of cannulation and of the pump oxygenator design and operation.

Swimming training lowers the resting blood pressure in individuals with hypertension.

BACKGROUND: Despite the fact that swimming is often recommended for the prevention and treatment of hypertension, no study has examined the potential efficacy of regular swimming exercise for lowering the blood pressure in hypertensive humans. OBJECTIVE: To test the hypothesis that regular swimming exercise lowers the resting blood pressure. DESIGN: A 10-week closely supervised swimming training program compared with a non-exercising control group. PATIENTS: Eighteen previously sedentary men and women [aged 48 +/- 2 years (mean +/- SEM)] with stage 1 or 2 essential hypertension. RESULTS: The resting heart rated, an index of cardiovascular adaptation, decreased in the swimming training group from 81 +/- 4 to 71 +/- 3 beats/min (P < 0.01). The body mass and body fat percentage did not show statistically significant changes. The systolic blood pressure of patients in the seated position fell significantly (P < 0.05) from 150 +/- 5 to 144 +/- 4 mmHg. The seated diastolic blood pressure did not change significantly. A similar magnitude of reductions in systolic blood pressure (P < 0.05) was also found in patients in the supine position. No significant changes in plasma catecholamine concentrations, casual forearm vascular resistance, plasma volume and blood volume were observed. There were no significant changes in any of these variables in the control group. CONCLUSION: Swimming training elicits significant reductions in arterial blood pressure at rest in individuals with hypertension. This is a clinically important finding since swimming can be a highly useful alternative to land-based exercises for hypertensive patients with obesity, exercise-induced asthma, or orthopedic injuries.