Continuous recording of direct arterial pressure in unrestricted patients. Its role in the diagnosis and management of high blood pressure.

We have compared casual indirect measurements of arterial pressure obtained 1) by the general practitioner (GP) and 2) in the outpatient clinic (OPC) with 24 hour continuous recording of direct arterial pressure in two selected group of unrestricted patients. 1) Eight asymptomatic, untreated patients with suspected hypertension. 2) Eight asymptomatic, treated patients whose indirect pressure readings seemed inappropriately high when considered against a general absence of target organ damage. Both groups showed that usually there was good agreement between arterial pressure recorded indirectly by GP and OPC while continuous recording showed wide variability of systolic and diastolic pressures over 24 hours and a significant fall during sleep. The first groups with suspected hypertension showed that the indirect measurements were not significantly different from the 24 hour direct recording. The second group of patients on treatment for hypertension showed a discrepancy, the direct readings being significantly lower than the indirect. This difference (approixmately 30 mm Hg mean arterial pressure) would explain the lack of target organ damage and may have been due to the effect of exercise augmenting the hypotensive action of drugs or due to a well developed defense reflex which biased the indirect readings.