How should diastolic blood pressure be defined during pregnancy?

Area of Science:

• Obstetrics and Gynecology
• Cardiovascular Physiology
• Medical Instrumentation

Background:

• Accurate measurement of diastolic blood pressure in pregnancy is crucial but debated.
• Korotkoff sound phases IV (muffling) and V (disappearance) are commonly used auscultatory methods.
• Previous research established K2 analysis as a noninvasive, accurate method in nonpregnant subjects.

Purpose of the Study:

• To compare the accuracy of K2 analysis with auscultatory methods (muffling and disappearance) for diastolic blood pressure in pregnant women.
• To evaluate the reliability of muffling and disappearance phases in hypertensive and normotensive pregnancies.

Main Methods:

• 58 women (42 hypertensive, 16 normotensive) underwent 556 blood pressure evaluations.
• Simultaneous K2 analysis and auscultation by two observers (A1, A2) were performed.
• Agreement between observers and comparison of auscultatory phases with K2 diastolic pressure were analyzed.

Main Results:

• Muffling was inconsistently detected, with lower prevalence in hypertensive pregnancies (A1: 47.5%, A2: 37.3%) vs. normotensive (A1: 73.2%, A2: 66.7%).
• Observer agreement on muffling was low (112/348 instances).
• Disappearance of sound closely approximated K2 diastolic pressure in hypertensive subjects, with a slight underestimation in normotensive subjects.

Conclusions:

• Disappearance of Korotkoff sounds (phase V) is a more reliable indicator of diastolic blood pressure in pregnancy than muffling (phase IV).
• K2 analysis offers a precise, noninvasive alternative for diastolic blood pressure monitoring in pregnant individuals.
• Clinical classification impacts the detection of Korotkoff sound muffling, highlighting its limitations.