WHICH KOROTKOFF SOUND SHOULD BE USED FOR THE DIASTOLIC BLOOD-PRESSUREIN PREGNANCY

There is a gathering momentum favouring the adoption of the 5th Korotk off sound to identify diastolic blood pressure in pregnancy. Our objec tive was to measure interobserver reliability for indirect blood press ure measurement in pregnancy for systolic and diastolic measurements a nd to calculate the difference in diastolic pressure measured by the 4 th and 5th Korotkoff sounds. To minimize bias we used trained but prev iously inexperienced observers with proven, normal auditory acuity. Th e observers were paired in 4 teams and performed a series of 334 blind ed, simultaneous observations of systolic and diastolic blood pressure measurements taken from pregnant women between 12-41 weeks' gestation . Reliability was measured by intraclass correlation coefficient for p aired measures and kappa for the detection or nondetection of 4th (K4) and 5th (K5) Korotkoff sounds. K4 was undetected in 36% of observatio ns and K5 was undetected in 2% of observations. Reliability for detect ion or nondetection of Korotkoff sounds was fair for K4 (kappa 0.36) a nd moderate for K5 (kappa 0.58). Reliability was good between observer s for systolic, K4 and K5 diastolic measurements (intraclass correlati on greater than or equal to 0.80). The mean difference between the dia stolic pressure measured by K4 and K5 was 15 mmHg for all measurements and 8 mmHg for the top quartile of measurements (p <0.001). We found K5 to be more often and more reliably detected than K4. If units adopt K5 in preference to K4, consideration will need to be given to loweri ng treatment thresholds for women with borderline or mild hypertension .