Low predictive value of positive Osler manoeuvre for diagnosing pseudohypertension

Pseudohypertension is a condition where indirectly determined BP (e.g. via sphygmomanometry) significantly overestimates actual intraarterial pressure. A patient who has a palpable, although pulseless, radial artery while the blood pressure cuff is inflated above systolic pressure, has a positive 'Osler sign'. This 'Osler manoeuvre' has been reported to predict the presence of pseudohypertension. To evaluate its importance in diagnosing pseudohypertension, 19 hypertensive patients deemed Osler-positive by at least two observers were studied. BP was determined indirectly using a stethoscope and mercury sphygmomanometer. Intraarterial pressure was determined by a brachial artery catheter-transducer-monitoring system. For both pressure-measurement techniques and each patient, six readings were averaged to give a single systolic and diastolic value. Mean arterial pressure was calculated as diastolic pressure plus one-third the pulse pressure. Pseudohypertension was defined as a sphygmomanometric mean pressure that exceeded intraarterial mean pressure by > or = 10 mmHg. In this group of 19 Osler-positive patients, stethoscope-sphygmomanometry underestimated systolic and overestimated diastolic intraarterial pressure. For mean pressure, sphygmomanometry was > or = 10 mmHg higher than intraarterial in two patients and > or = 10 mmHg lower than intraarterial in three patients. Thus, while two patients had pseudohypertension, three could be considered to have pseudohypotension, defined as a condition where indirect blood pressure significantly underestimates intraarterial pressure. Accordingly, a positive Osler manoeuvre did not reliably predict the presence of pseudohypertension in this population.