Circadian rhythm of blood pressure in hypertensive adult patients: implications for blood pressure determination.

To determine whether traditionally timed (0800, 1600, and 2400 hr) blood pressure assessments by nurses reflect circadian peaks and troughs, blood pressure was measured indirectly every 2 hr for 24 hr with a mercury sphygmomanometer and a Sprague-Rapaport stethoscope in a sample of 31 hypertensive adult patients in a university hospital. Pooled mean systolic and diastolic readings portrayed a circadian rhythm with the peak occurring most frequently at 1600 and the trough at 0400 hr. The mean range of variability was 29.54 mm Hg for systolic pressure and 21.54 mm Hg for diastolic pressure. Two-tailed t tests demonstrated statistically significant (P less than .001) differences between peak and 0800 systolic pressure, peak and 2400 systolic pressure, peak and 0800 diastolic pressure, and peak and 2400 diastolic pressure. No significant differences were found between peak and 1600 systolic and diastolic assessments. There were statistically significant (P less than .001) t test differences between trough systolic and diastolic pressure and traditionally timed blood pressure readings. These findings have clinical nursing implications for the timing of blood pressure assessments of hospitalized hypertensive adult patients.