Correlation of Noninvasive Blood Pressure and Invasive Intra-arterial Blood Pressure in Patients Treated with Vasoactive Medications in a Neurocritical Care Unit

Ali A. Saherwala, Sonja E. Stutzman, Mohamed Osman, Junaid Kalia, Stephen A. Figueroa, Dai Wai M. Olson, Venkatesh Aiyagari

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Background: The correlation between noninvasive (oscillometric) blood pressure (NBP) and intra-arterial blood pressure (IAP) in critically ill patients receiving vasoactive medications in a Neurocritical Care Unit has not been systematically studied. The purpose of this study is to examine the relationship between simultaneously measured NBP and IAP recordings in these patients. Methods: Prospective observational study of patients (N = 70) admitted to a neurocritical care unit receiving continuous vasopressor or antihypertensive infusions. Paired NBP/IAP observations along with covariate and demographic data were abstracted via chart audit. Analysis was performed using SAS v9.4. Results: A total of 2177 paired NBP/IAP observations from 70 subjects (49% male, 63% white, mean age 59 years) receiving vasopressors (n = 21) or antihypertensive agents (n = 49) were collected. Paired t test analysis showed significant differences between NBP versus IAP readings: ([systolic blood pressure (SBP): mean = 136 vs. 140 mmHg; p < 0.0001], [diastolic blood pressure (DBP): mean = 70 vs. 68 mmHg, p < 0.0001], [mean arterial blood pressure (MAP): mean = 86 vs. 90 mmHg, p < 0.0001]). Bland–Altman plots for MAP, SBP, and DBP demonstrate good inter-method agreement between paired measures (excluding outliers) and demonstrate NBP–IAP SBP differences at extremes of blood pressures. Pearson correlation coefficients show strong positive correlations for paired MAP (r = 0.82), SBP (r = 0.84), and DBP (r = 0.73) recordings. An absolute NBP–IAP SBP difference of > 20 mmHg was seen in ~ 20% of observations of nicardipine, ~ 25% of observations of norepinephrine, and ~ 35% of observations of phenylephrine. For MAP, the corresponding numbers were ~ 10, 15, and 25% for nicardipine, norepinephrine, and phenylephrine, respectively. Conclusion: Despite overall strong positive correlations between paired NBP and IAP readings of MAP and SBP, clinically relevant differences in blood pressure are frequent. When treating with vasoactive infusions targeted to a specific BP goal, it is important to keep in mind that NBP and IAP values are not interchangeable.

Original languageEnglish (US)
Pages (from-to)1-8
Number of pages8
JournalNeurocritical Care
DOIs
StateAccepted/In press - Mar 22 2018

Keywords

  • Blood pressure
  • Hemodynamics
  • Invasive arterial blood pressure monitoring
  • Monitoring
  • Neurocritical care
  • Pharmacology

ASJC Scopus subject areas

  • Clinical Neurology
  • Critical Care and Intensive Care Medicine

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