RESUMEN
RATIONALE: Noninvasive blood pressure (BP) monitoring is very important also difficult for accurate diagnosis and monitor of obese patients. AIMS: The study aimed to assess the agreement between forearm arm BP and intra-arterial BP values in a different body and arm positions in obese patients. METHODS: The descriptive study was carried out on 60 intensive care patients with a body mass index above 30 kg/m2 who were monitored with invasive radial BP in the general and surgical intensive care units. BP values obtained from the upper arm and forearm with different arm and body positions were compared with intra-arterial BP results. Bland-Altman analysis and correlation coefficient were used for the accuracy of upper and forearm noninvasive BP reading in different positions. RESULTS: The best agreement was found between the forearm systolic BP in the supine and half-sitting position with the arm down and intra-arterial BP values. Also, the best agreement in diastolic BP was found between the half-sitting and half-sitting position with the arm down and intra-arterial BP. CONCLUSIONS: Forearm systolic BP measurement, especially in the supine and half-sitting position with the arm below the heart level position, was best agreement with intra-arterial measurement, regarded as the gold standard. For this reason, it is more appropriate to use forearm BP measurement in obese patients monitored in intensive care to obtain accurate results.
RESUMEN
BACKGROUND: Forearm blood pressures have been suggested as an alternative site to measure blood pressures when the upper arm is unavailable. However there is little evidence utilising clinical populations to support this substitution. OBJECTIVES: To determine agreement between blood pressures measured in the left upper arm and forearm using a singular oscillometric non-invasive device in adult Emergency Department patients. The secondary objective was to explore the relationship of blood pressure differences with age, sex, ethnicity, smoking history and obesity. DESIGN: Single centre comparison study. SETTING: Adult Emergency Department, Tertiary Trauma Centre. PARTICIPANTS: Forty-four participants who met inclusion/exclusion criteria selected sequentially from the Emergency Department arrival board. METHODS: A random assignment of order of measurement for left upper arm and forearm blood pressures was utilised. Participants were eligible if they were aged 18 years or older, had been assigned an Australasian Triage Scale code of 2, 3, 4, or 5, were able to consent, and able to have blood pressures measured on their left arm whilst lying at a 45° angle. The Bland-Altman method of statistical analysis was used, with the level of agreement for clinical acceptability for the systolic, diastolic and mean arterial pressure defined as ±10 mmHg. RESULTS: The forearm measure overestimated systolic (mean difference 2.2 mmHg, 95% limits of agreement ±19 mmHg), diastolic (mean difference 3.4 mmHg, 95% limits of agreement ±14.4 mmHg), and mean arterial pressures (mean difference 4.1 mmHg, 95% limits of agreement ±13.7 mmHg). The systolic measure was not significantly different from zero. Evidence of better agreement was found with upper arm/forearm systolic measures below 140 mmHg compared to systolic measures above 140 mmHg using the Levene's test (p=0.002, F-statistic=11.09). Blood pressure disparity was not associated with participant characteristics. CONCLUSIONS: Forearm measures cannot routinely replace upper arm measures for blood pressure measurement. If the clinical picture requires use of forearm blood pressure, the potential variance from an upper arm measure is ±19 mmHg for systolic pressure, although the variability may be close to ±10 mmHg if the systolic blood pressure is below 140 mmHg.