HEMODYNAMIC AND HORMONAL RESPONSE TO A STREAM OF COOLED AIR

Many patients with angina note that their symptoms deteriorate in cold weather, although the precise physiological mechanism that explains t his remains unclear. Exposure of the face to cool winds may be a contr ibutory factor. The cardiovascular and hormonal response to a localise d stream of room (22 degrees C) and cold (4 degrees C) air during subm aximal treadmill exercise was therefore studied in nine normal subject s. Cardiac output and respiratory gases were measured with a mass spec trometer, using the indirect Fick principle. Blood samples were taken for plasma noradrenaline. A localised stream of air at 5 m . s(-1) pro duced significant cardiovascular effects at rest, some of which persis ted during exercise. In response to cold air, stroke volume, cardiac o utput, blood pressure and oxygen uptake increased (all P < 0.05). Ther e was a trend towards a reduction in heart rate at rest and increase i n plasma noradrenaline. Room air caused a reduction in blood pressure (P = 0.01) but stroke volumes and oxygen uptake were unchanged. The re sults of this study demonstrate significant cardiovascular effects of a cooled air facial stimulus at rest and during exercise. They may, in part, explain the effects of cold winds on patients with angina.