Oscillometric blood pressure measurement: the methodology, some observations, and suggestions.

Most noninvasive blood pressure (NIBP) devices use the oscillometric method. Published studies of oscillometric methodology introduced varied algorithmic approaches for determination of systolic (SBP), diastolic (DBP), and mean arterial (MAP) blood pressures. While there is a general agreement about MAP determination, controversy exists about the determination of SBP and DBP Accuracy of oscillometric devices has been questioned and validation studies have revealed problems. Several validation protocols have been developed but they are expensive and time consuming to conduct and they have their own limitations. Instruments for bench testing of NIBP devices are useful for some device functions, but they cannot perform dynamic accuracy tests. The issue of accuracy is becoming very important as health care professionals increasingly rely on electronic NIBP devices. The authors developed a compact system for acquisition of NIBP waveforms. Some representative oscillometric waveforms are introduced here to demonstrate the oscillometric method and its shortcomings. A finger photoplethysmograph (PPG) was used to demonstrate a potential improvement of SBP determination. The concept and significance of an oscillometric blood pressure waveform database is introduced and its applications are discussed.

International Session Award. Non-invasive cutaneous cardiovascular dynamics (CVD) as a predictor of preterm delivery: a pilot study.

AIM: To assess the clinical value of cardiovascular dynamics (CVD) pattern of 'positive cycling' in predicting true preterm labor. METHODS: Patients with a clinical diagnosis of preterm labor had CVD measurement with a non-invasive miniature pressure transducer applied to the fingertip concomitantly with uterine activity monitoring. Based on previous work by our group, the rapid ejection time (RET) reflects arterial compliance; an elevated RET is suggestive of vasoconstriction. Positive cycling is present when the RET shows elevation with uterine contractions and negative cycling is present when there are no changes in the RET with uterine contractions. RESULTS: Twenty-seven women had negative CVD cycling and nine had positive CVD cycling. There was no difference between the two groups in initial gestational age, cervical effacement or cervical dilation at testing. However, the mean interval from testing to delivery was 1.56 (SEM+/-0.29) days for positive cycling and 39 days (+/-5.25) for negative cycling (P < 0.001). CONCLUSION: Non-invasive cardiovascular patterns of positive cycling appear predictive of preterm delivery.

The effects of cardiovascular dynamics monitoring in the outpatient management of pregnancy hypertension.

OBJECTIVE: Our purpose was to assess the effects of the adjunctive use of cardiovascular dynamics monitoring in the ambulatory management of 199 pregnant patients with severe hypertension. STUDY DESIGN: A prospective, observational study was performed. Determinants of mean arterial pressure were computed by using the Hon monitor. Indicators of arterial compliance and effective blood volume were developed. All patients were monitored in the outpatient clinic; additionally, 19 patients self-tested at home. No rigid medication protocol was followed, but furosemide was used in most cases when cardiovascular dynamics monitoring patterns were consistent with volume loading. Otherwise, vasodilators were prescribed. The t test for independent samples was used to compare the home-monitored subgroup with the outpatient-only group. RESULTS: Pregnancy was prolonged by 74 +/- 63.9 days (mean +/- SD). Mean gestation was 37.6 +/- 2.9 weeks, and mean birth weight was 2882.4 +/- 837 g. The primary cesarean delivery rate was 23.7%, but only 15 (7.5%) cesarean deliveries were performed because of failed therapy. The 19 home-monitored patients gained 108 +/- 75 days (83.1 +/- 42.2 days beyond 20 weeks). CONCLUSION: Adjunctive cardiovascular dynamics monitoring may have a role in the evaluation and management of hypertension during pregnancy.