De vijfde, maar niet de vierde Korotkoff-toon, is goed reproduceerbaar bij zwangeren

Objective. To determine the detection rate and the reproducibility of the first (K(I)), the fourth (K₄) and the fifth (K₅) phase of the Korotkoff sounds in pregnant women. Design. Cross-sectional study. Methods. Data obtained in a validation study of an ambulatory blood pressure measuring device were re-analysed. In 77 pregnant women attending the Obstetrics department of the University Hospital Utrecht, the Netherlands, two trained observers took 231 simultaneous blood pressure measurements (in each woman three) with a shared mercury sphygmomanometer and a multiaural stethoscope. Detection rates, percentages of observer agreement within 5 mmHg and kappa values were calculated for K(I), K₄ and K₅. Results. Both observers were able to detect K(I), K₄ and K₅ in 98%, 24% and 98% of all 231 measurements respectively. In 46% of measurements and in 23% of women, neither observer detected K₄. Where both observers heard the sound, they agreed within 5 mmHg in 98% (K: 0.99), 69% (K: 0.42) and 96% 0.99) of measurements for K(I), K₄ and K₅ respectively. Conclusion. K₄ cannot be detected and reproduced accurately in a significant proportion of pregnant women, and therefore is not the preferable diastolic endpoint in pregnancy. Detection rates and reproducibility of K(I) and K₅ are excellent.