Arterial Monitoring System Leveling Method, Transducer Location, and Accuracy of Blood Pressure Measurements

Background Many critically ill patients have invasive arterial catheters inserted for blood pressure monitoring. Whether catheter leveling method and alternative transducer location affect the accuracy of blood pressure measurements is unknown. Objective To determine whether the use of alternative transducer locations and visual alignment versus laser device leveling significantly affect the accuracy of blood pressure measurements. Methods A convenience sample of 36 participants were randomly assigned to 1 of 3 experimental groups with different transducer locations: taped to the upper arm, next to the upper arm taped to a rolled cloth, or at the wrist. Participants served as their own controls; the control condition was having the transducer on the intravenous pole. Four blood pressure measurements were recorded for each patient (2 from each of the experimental and control conditions) using visual alignment and then laser device leveling. Results Only diastolic blood pressure (DBP) differed significantly between leveling methods (P = .01); no pressures differed significantly by transducer location. Covariate analysis indicated expected relationships between (1) age and DBP (P = .001), (2) Simplified Acute Physiology Score II and both DBP (P = .003) and mean arterial pressure (P = .03), and (3) duration of mechanical ventilation and DBP (P = .05). Conclusion The findings indicate that any of the transducer locations evaluated may be useful in clinical prac-tice. Also, visual alignment rather than laser device leveling may be acceptable, except for DBP in the control location. More research is needed to strengthen these findings.