Basic Principles of Noninvasive Blood Pressure Measurement in Infants

Authors and Disclosures

Andrea D. Stebor, RN, PhD, Clinical Research Department, Tampa Center of Excellence, GE Healthcare Technologies, Tampa, Fla., Mary A. Short, RN, MSN, Series Editor, Foundations in Newborn Care

Sidebar: Series Editor's Note

The Foundations in Newborn Care Series provides foundational information to nurses that can be used for self-study, as well as for orientation or review courses. This issue reviews the fundamental principles of the widely used oscillometric method of BP measurement. The author outlines a step-by-step guide to NIBP measurement and includes strategies to ensure appropriate technique that can assist the nurse in providing an accurate BP measurement.

It is important to understand that even an accurately obtained normal BP does not equate to a normal hemodynamic status. Infants normally have a lower BP and maintain a higher vascular tone than adults. Infants can maintain a normal BP through compensatory mechanisms such as vasoconstriction and increasing their heart rate. Hypotension is a late sign of shock in an infant, and once hypotension occurs, cardiovascular collapse may soon follow. Therefore, BP by itself is not a reliable endpoint for assessing the adequacy of cardiovascular status or resuscitation. The nurse should evaluate BP measurements within the context of the infant's history and current clinical assessment.

Sidebar: How is The Accuracy of Bp Monitors Established?

Manufacturers must provide accuracy data for their noninvasive blood pressure monitors to the U.S. Food and Drug Administration before they can market them. The accuracy study for the monitor should follow the guidelines of the American National Standard for Manual, Electronic, or Automated Sphygmomanometers (ANSI/AAMI SP10), which specify strict study methodology and accuracy criteria.^[37] A device that meets the ANSI/AAMI SP10 standard requirements satisfies the requirements for accurate clinical measurement of BP. The standard also requires that each manufacturer provide appropriate instructions for use. Strict adherance to proper technique, as outlined by the manufacturer, is essential to increase the accuracy of any measurement from a device. Sampling criteria ensure that the study samples are representative of the population. For neonatal populations, the sample must include a minimum of 15 neonates; 9 must meet the criteria of the weight categories outlined below.

The accuracy study criteria for the comparisons between the systolic, diastolic, and MAP values from the noninvasive blood pressure monitor and the intra-arterial blood pressure reference standard require that the overall mean difference of the paired comparisons be within ±5 mm Hg with a standard deviation ≤8 mm Hg. The mean difference and standard deviation calculated from a sample containing a minimum of 100 NIBP measurements must meet these criteria before a device can claim to meet the requirements of this standard.

Weights and Sampling Requirements for Neonates in an NIBP Accuracy Study^[37]