PURPOSE:In intensive care units (ICU) monitoring of systolic, diastolic and mean arterial blood pressure can be done by non-invasive oscillometric techniques (NIBP). Previous studies have confirmed accuracy and precision in ambulatory patients when compared with intra-arterial blood pressure (IABP). However, there are no studies evaluating the accuracy or precision of NIBP monitoring in routine or complex ICU patients at alternate sites such as the lower extremities. The goal of our study was to compare NIBP measurements of upper and lower extremities in this population using IABP as the criterion standard.
METHODS:Sixty-eight (68) ICU patients with arterial lines were screened and twenty-nine (29) patients were enrolled based on inclusion/exclusion criteria. Arterial catheters were calibrated per standard ICU protocol, and NIBP measurements were acquired using a standard oscillometric monitoring system per nursing and manufacturer's protocols from the arm, wrist, ankle and thighs. Measurements at the wrist and arm were categorized as upper extremity, and measurements at the ankle and thigh were categorized as lower extremity. Demographics, medications, laboratory values and edema scores were documented and analyzed by standard statistical methods.
RESULTS:Two hundred sixty-one (261) blood pressure measurements in twenty-nine patients (n=29) were recorded. Upper and lower extremity oscillometric mean arterial pressure (MAP) measurements were plotted against each other and the coefficient of determination (R2) was calculated (R2=0.08). Upper extremity and lower extremity MAP measurements were also plotted against arterial line measurements, and the R2 was calculated for each (Upper Extremity MAP vs A-line MAP: R2=0.47; Lower Extremity MAP vs A-line MAP: R2=0.01).
CONCLUSION:Limited correlation existed in NIBP measurements between upper and lower extremities in an ICU patient population. Additionally, limited correlation was found between NIBP and IAPB measurements of blood pressure in these patients.
CLINICAL IMPLICATIONS:Based on this data, caution must be exercised when using non-invasive blood pressure measurements in clinical decision making in intensive care populations.
DISCLOSURE:Kirk DePriest, None.