Invasive and concomitant noninvasive intraoperative blood pressure monitoring: Observed differences in measurements and associated therapeutic interventions

Background: Noninvasive (NIBP) and intraarterial (ABP) blood pressure monitoring are used under different circumstances and may yield different values. The authors endeavored to characterize these differences and hypothesized that there could be differences in interventions associated with the use of ABP alone ([ABP]) versus ABP in combination with NIBP ([ABP+NIBP]). Methods: Simultaneous measurements of ABP and NIBP made during noncardiac cases were extracted from electronic anesthesia records; the differences were subjected to regression analysis. Records of blood products, vasopressors, and antihypertensives administered were also extracted, and associations between the use of these therapies and monitoring strategy ([ABP] vs. [ABP+NIBP]) were tested using univariate, multivariate, and propensity score matched analyses. RESULTS:: Among 24,225 cases, 63% and 37% used [ABP+NIBP] and [ABP], respectively. Systolic NIBP was likely to be higher than ABP when ABP was less than 111 mmHg and lower than ABP otherwise. Among patients with hypotension, transfusion occurred in 27% versus 43% of patients in the [ABP+NIBP] versus [ABP] group, respectively (odds ratio = 0.4; 95% CI 0.35-0.46), and 7% versus 18% of patients in the [ABP+NIBP] versus [ABP] group received vasopressor infusions, respectively (P < 0.01). Among hypertensive patients, 12% versus 44% of those in the [ABP+NIBP] versus [ABP] group received antihypertensive agents, respectively (P < 0.01). Conclusions: NIBP was generally higher than ABP during periods of hypotension and lower than ABP during periods of hypertension. The use of NIBP measurements to supplement ABP measurements was associated with decreased use of blood transfusions, vasopressor infusions, and antihypertensive medications compared with the use of ABP alone.