The effect of a change in ambient temperature on blood pressure in normotensives

The aim of this study was to investigate the influence of ambient temperatu re on blood pressure (BP). BP measurements were taken in 20 normotensive vo lunteers who stayed in Greenland for a B-week period, Measurements of systo lic (SBP), diastolic (DBP) and heart rate (HR) were taken before (3 session s), during (7-8 sessions) and after the journey (3 sessions). Each session consisted of five BP measurements in the supine position after at least 5 m in rest. All five readings were averaged. Temperature data (mean +/- s.d.), collected from meteorological services, before, during and after Greenland were 15.7 +/- 0.6, 0.5 +/- 1.5 and 8.2 +/- 0.8 degreesC, SEP values were 1 16 +/- 7.0, 122 +/- 7.6 and 116 +/- 7.4 and DBP 63 +/- 5.2, 66 +/- 5.8 and 65 +/- 6.5 mm Hg, respectively. HR amounted to 58 +/- 7.4, 61 +/- 6.7 and 6 0 +/- 7.4 bpm, Significant differences existed between, before and during f or SEP and DBP and between, during and after for SEP. Readings were grouped in four categories based on the temperature at the time of reading. For SE P as well as DBP a clear dose-response relationship was demonstrated betwee n low temperature and high BP, although for DBP only a few correlations wer e statistically significant. Mean correlation coefficients for SEP and DBP against temperature were -0.44 (P < 0.001) and -0.27 (P < 0.005), respectiv ely. Our results are in favour of a moderate, but both significant and rele vant increase in SEP and DBP when moving from higher to lower ambient tempe rature.