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Methods of Blood Pressure Measurement in the ICU*

Lehman, Li-wei H. PhD1,2; Saeed, Mohammed MD, PhD1,2,3; Talmor, Daniel MD4; Mark, Roger MD, PhD1,2; Malhotra, Atul MD5

doi: 10.1097/CCM.0b013e318265ea46
Clinical Investigations

Objective: Minimal clinical research has investigated the significance of different blood pressure monitoring techniques in the ICU and whether systolic vs. mean blood pressures should be targeted in therapeutic protocols and in defining clinical study cohorts. The objectives of this study are to compare real-world invasive arterial blood pressure with noninvasive blood pressure, and to determine if differences between the two techniques have clinical implications.

Design: We conducted a retrospective study comparing invasive arterial blood pressure and noninvasive blood pressure measurements using a large ICU database. We performed pairwise comparison between concurrent measures of invasive arterial blood pressure and noninvasive blood pressure. We studied the association of systolic and mean invasive arterial blood pressure and noninvasive blood pressure with acute kidney injury, and with ICU mortality.

Setting: Adult intensive care units at a tertiary care hospital.

Patients: Adult patients admitted to intensive care units between 2001 and 2007.

Interventions: None.

Measurements and Main Results: Pairwise analysis of 27,022 simultaneously measured invasive arterial blood pressure/noninvasive blood pressure pairs indicated that noninvasive blood pressure overestimated systolic invasive arterial blood pressure during hypotension. Analysis of acute kidney injury and ICU mortality involved 1,633 and 4,957 patients, respectively. Our results indicated that hypotensive systolic noninvasive blood pressure readings were associated with a higher acute kidney injury prevalence (p = 0.008) and ICU mortality (p < 0.001) than systolic invasive arterial blood pressure in the same range (≤70 mm Hg). Noninvasive blood pressure and invasive arterial blood pressure mean arterial pressures showed better agreement; acute kidney injury prevalence (p = 0.28) and ICU mortality (p = 0.76) associated with hypotensive mean arterial pressure readings (≤60 mm Hg) were independent of measurement technique.

Conclusions: Clinically significant discrepancies exist between invasive and noninvasive systolic blood pressure measurements during hypotension. Mean blood pressure from both techniques may be interpreted in a consistent manner in assessing patients’ prognosis. Our results suggest that mean rather than systolic blood pressure is the preferred metric in the ICU to guide therapy.

Supplemental Digital Content is available in the text.

1 Massachusetts Institute of Technology Cambridge, MA.

2 The Harvard-MIT Division of Health Sciences & Technology, Cambridge, MA.

3 University of Michigan Hospital (MS), Ann Arbor, MI.

4 Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA.

5 Divisions of Pulmonary & Critical Care and Sleep Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA.

*See also p. 333.

Drs. Lehman and Saeed have contributed equally as co-first authors.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (

This work was supported by award number R01EB001659 from the National Institute of Biomedical Imaging and Bioengineering. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Biomedical Imaging and Bioengineering or the National Institutes of Health. Dr. Malhotra is funded by NIH R01 HL090897, R01 HL085188, AHA 0840159N1, NIH P01 HL 095491, and NIH K24 HL 093218.

Dr. Mohammed Saeed is a part-time employee at Philips Healthcare. Dr. Malhotra had consulting and research income from Philips Respironics, but has relinquished all outside personal income since May 2012. The remaining authors have not disclosed any potential conflicts of interest.

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© 2013 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins