Clinical comparison of automatic, noninvasive measurements of blood pressure in the forearm and upper arm with the patient supine or with the head of the bed raised 45 degrees: a follow-up study.

BACKGROUND: Noninvasive measurement of blood pressure in the forearm is used when the upper arm is inaccessible and/or when available blood pressure cuffs do not fit a patient's arm. Evidence supporting this practice is limited. OBJECTIVE: To compare noninvasive measurements of blood pressure in the forearm and upper arm of medical-surgical inpatients positioned supine and with the head of the bed raised 45 degrees . METHODS: Cuff size was selected on the basis of forearm and upper arm circumference and manufacturers' recommendations. With a Welch Allyn Vital Signs 420 Series monitor, blood pressures were measured in the forearm and then in the upper arm of 221 supine patients with their arms resting at their sides. Patients were repositioned with the head of the bed elevated 45 degrees and after 2 minutes, blood pressures were measured in the upper arm and then the forearm. Starting position was alternated on subsequent subjects. RESULTS: Paired t tests revealed significant differences between systolic and diastolic blood pressures measured in the upper arm and forearm with patients supine and with the head of the bed elevated 45 degrees . The Bland-Altman procedure revealed that the distances between the mean values and the limits of agreement were from 15 to 33 mm Hg for individual subjects. CONCLUSIONS: Noninvasive measurements of blood pressure in the forearm and upper arm cannot be interchanged in medical-surgical patients who are supine or in patients with the head of the bed elevated 45 degrees .

Clinical comparison of automatic, noninvasive measurements of blood pressure in the forearm and upper arm.

BACKGROUND: When the upper arm (area from shoulder to elbow) is inaccessible and/or a standard-sized blood pressure cuff does not fit, some healthcare workers use the forearm to measure blood pressure. OBJECTIVE: To compare automatic noninvasive measurements of blood pressure in the upper arm and forearm. METHODS: A descriptive, correlational comparison study was conducted in the emergency department of a 1071-bed teaching hospital. Subjects were 204 English-speaking patients 6 to 91 years old in medically stable condition who had entered the department on foot or by wheelchair and who had no exclusions to using their left upper extremity. A Welch Allyn Vital Signs 420 series monitor was used to measure blood pressure in the left upper arm and forearm with the subject seated and the upper arm or forearm at heart level. RESULTS: Pearson r correlation coefficients between measurements in the upper arm and forearm were 0.88 for systolic blood pressure and 0.76 for diastolic blood pressure (P < .001 for both). Mean systolic pressures, but not mean diastolic pressures, in the upper arm and forearm differed significantly (t = 2.07, P = .04). A Bland-Altman analysis indicated that the distances between the mean values and the limits of agreement for the 2 sites ranged from 15 mm Hg (mean arterial pressure) to 18.4 mm Hg (systolic pressure). CONCLUSIONS: Despite strict attention to correct cuff size and placement of the upper arm or forearm at heart level, measurements of blood pressure obtained noninvasively in the arm and forearm of seated patients in stable condition are not interchangeable.