Blood pressure measurement during pregnancy: auscultatory versus oscillatory methods.

OBJECTIVE

To determine the equivalence of auscultatory and oscillatory blood pressure measurements.

SETTING

Inner-city prenatal clinic.

PARTICIPANTS

Eighty-one women in their 2nd to 9th month of pregnancy.

DESIGN

Participants were assessed for systolic and diastolic blood pressures on left and right arms using auscultatory (manual) and oscillatory (electronic) methods. A correlational study design was used.

MAIN OUTCOME MEASURES

Differences in pressures related to arm and method of measurement.

RESULTS

The oscillatory method produced consistently higher readings for both systolic (F[1,80] = 45.9, p < 0.001) and diastolic (F[1,80] = 25.79, p < 0.001) pressure readings. Correlations between estimates generally treated as substitutable all fell below the recommended level of 0.80 for measurement equivalence.

CONCLUSIONS

Results suggest the need for caution when interpreting blood pressure estimates as interchangeable. This is particularly important when patients move from clinic settings, where auscultatory methods predominate, to inpatient settings, where oscillatory methods of measurement are used.