The changes in the intra-arterial pressure during immersion of the hand in ice-cold water.

The response of the intra-arterial pressure to the cold immersion stimulus was studied in 42 healthy young adults, continuous direct (arterial-pressure) recording being used. The average systolic elevation was 22.6 mm. Hg and the average diastolic elevation was 16.3 mm. Hg. The difference between direct and indirect methods of measuring blood pressure was studied in 351 simultaneous determinations in 35 of these young adults. The direct systolic pressure averaged 9.7 mm. Hg higher and the diastolic pressure was 7.3 mm. Hg lower than the indirect measurement. T HE cold pressor test of Hines and Brown1 has been used widely during the past 22 years in the study of essential hyper-tension2-9 and the toxemias of pregnancy.'0 11 Up to the present, exact knowledge of the nature and significance of the cold pressor response has been limited by the intermittent measurements possible with the sphygmomanometer. However, now that continuous direct recording of arterial pressure is established as an accurate and reliable laboratory procedure, a new tool is available for the study of the cold pressor test. The response of the intra-arterial pressure to the cold immersion stimulus (4 C. for 60 seconds) was studied in 42 healthy young adults, continuous direct arterial pressure recording being used. The cold pressor test of Hines and Brown was applied repeatedly at short intervals, and the direct record was examined with regard to (1) maximal elevation of pressure, (2) time required to reach the maximal pressure and (3) time needed to return to one half the maximal pressure (the last figure was taken as a measure of the recovery time). The difference between the direct and indirect methods of measuring blood pressure was studied in 351 simultaneous determina-tions in 35 of these young adults. In 1932, Hines and Brown' described an iceswatei immersion test (the cold pressor test) designed to measure individual vascular reactivity. Many methods of stimulation, including electric shocks, loud noise, bright lights and the inflicting of pain, had been tried previously. However, none of these stimuli gave consistent results when repeated in the same individual. Hines, working with the late Dr. G. E. Brown, had observed that a patient with cold sensitivity responded with a marked elevation of blood pressure when an extremity was immersed in ice water. The development andl application of this cold pressor test are described in the following papers." 4-8. The test has been used since by others,3 9-1 …