MEASURING BLOOD-PRESSURE IN PREGNANT-WOMEN - A COMPARISON OF DIRECT AND INDIRECT METHODS

OBJECTIVES: Our goals were to determine (1) whether Korotkoff phase IV or V sound was a more accurate measure of diastolic blood pressure in pregnancy and (2) interobserver variability of mercury sphygmomanomet ry of pregnant women. STUDY DESIGN: Direct (intraarterial) and indirec t (mercury sphygmomanometry) blood pressures were compared in 28 pregn ant women. Interobserver variability was assessed in a separate study of 86 pregnant women using four highly trained observers. RESULTS: (1) Routine sphygmomanometry underestimated direct systolic pressure by 1 1 (3, 18) mm Hg, p < 0.001 (median, interquartile range of differences ). Phase IV Korotkoff sound overestimated direct diastolic pressure by 9 (2, 12) mm Hg (p < 0.001) and phase V by 4 (2, 7) mm Hg (p = 0.04). Phase V-recorded diastolic pressure was closer to direct diastolic pr essure significantly more often (75%) than was phase IV-recorded diast olic pressure (21%) (p = 0.003). Mean arterial pressures did not diffe r significantly according to the method used. (2) Median blood pressur es did not differ among the four observers for systolic, diastolic pha se IV, or phase V recordings. Maximum difference for blood pressure re cording among observers was 4 (2, 6) mm Hg. CONCLUSIONS: Auscultatory sphygmomanometry in pregnant women underestimates systolic and overest imates diastolic blood pressure, but the phase V Korotkoff sound is mo re likely to represent the true diastolic pressure than is the phase I V sound.