CHEST Guidelines-Noninvasive-Arterial-Pressure-Measurements-at-the-

Noninvasive-Arterial-Pressure-Measurements-at-the-

Pdf Summary

This prospective study evaluated the influence of patient positioning—semi-recumbent versus horizontal—on noninvasive oscillometric arterial pressure (AP) measurements at the lower leg. The study was necessitated by situations where upper arm access is unavailable, and arterial catheterization isn't feasible. Common practice in acute care settings sees patients in semi-recumbent positions potentially leading to overestimated AP due to lower limb elevation above heart level.<br /><br />The study enrolled 50 ICU patients with radial artery catheters to compare noninvasive lower leg measurements against invasive AP readings. Patient positions were randomized between horizontal and semi-recumbent, with specific bed backrest angles: 0° for horizontal and 35°-45° for semi-recumbent.<br /><br />Results indicated a significant overestimation of mean arterial pressure (MAP) in the semi-recumbent position (bias +13.3 mm Hg) compared to a horizontal position (bias +3.8 mm Hg). The semi-recumbent position posed a systematic error risk with measurement errors leading to risk classification beyond acceptable standards. The study found poor agreement between lower leg and invasive measurements for systolic and diastolic AP, further weakened in the semi-recumbent position. Conversely, upper arm measurements showed negligible bias regardless of patient positioning.<br /><br />This study, the first to robustly assess position impact with invasive references, highlights significant measurement bias induced by the semi-recumbent position, urging adjustments in interpreting these readings. Subtracting 10 mm Hg from lower leg AP measurements in a semi-recumbent position is recommended for more accurate readings. The research emphasizes cautious interpretation of noninvasive AP measurements, particularly in specific patient demographics and devices, due to potential biases.

Keywords

patient positioning

semi-recumbent

horizontal

noninvasive measurements

arterial pressure

lower leg

ICU patients

measurement bias

mean arterial pressure

systematic error