Validation of arterial blood pressures observed from the patient monitor; a tool for prehospital research
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For some time, the inaccuracies of non-invasive blood pressure measurement in critically ill patients have been recognised. Measurement difficulties can occur even in optimal conditions, but in prehospital transportation vehicles, problems are exacerbated. Intra-arterial pressures must be used as the reference against which to compare the performance of non-invasive methods in the critically ill patient population. Intra-arterial manometer data observed from the patient monitor has frequently been used as the reference against which to assess the accuracy of noninvasive devices in the emergency setting. To test this method’s validity, this study aimed to determine whether numerical monitor pressures can be considered interchangeable with independently sampled intra-arterial pressures.
Intensive Care Unit nurses were asked to document arterial systolic, diastolic and mean pressures numerically displayed on the patient monitor. Observed pressures were compared to reference intra-arterial pressures independently recorded to a computer following analogue to digital conversion. Differences between observed and recorded pressures were evaluated using the Association for the Advancement of Medical Instrumentation (AAMI) protocol. Additionally, two-level linear mixed effects analyses and Bland-Altman comparisons were undertaken.
Systolic, diastolic and integrated mean pressures observed during 60 data collection sessions (n = 600) fulfilled AAMI protocol criteria. Integrated mean pressures were the most robust. For these pressures, mean error (reference minus observed) was 0.5 mm Hg (SD 1.4 mm Hg); 95% CI (two-level linear mixed effects analysis) 0.4–0.6 mm Hg; P < 0.001. Bland-Altman plots demonstrated tight 95% limits of agreement (−2.3 to 3.2 mm Hg), and uniform agreement across the range of mean blood pressures.
Integrated mean arterial pressures observed from a well maintained patient monitor can be considered interchangeable with independently sampled intra-arterial pressures and may be confidently used as the reference against which to test the accuracy of non-invasive blood pressure measuring methods in the prehospital or emergency setting.
Keywordsvalidation blood pressure monitoring prehospital non-invasive critical illness
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The authors would like to express their gratitude and admiration to the patients and families who participated in this study. This study relied on the cooperation of the nurses in the Intensive Care Unit at Flinders Medical Centre, and they are thanked for their professional and enthusiastic participation. Thanks are also extended to the hospital’s Biomedical Engineers for their willingness to share their expertise. Philips Medical Systems Australasia provided a blood pressure module that incorporated an analogue output jack for use during bedside data collection.
- 3.Gloyna DF, Huber P, Abston P, et al. A comparison of blood pressure measurement techniques in the hypotensive patient (Abstract). Anesth Analg. 1984;63:222.Google Scholar
- 5.van Bergen FH, Weatherhead DS, Treloar AE, et al. Comparison of indirect and direct methods of measuring arterial blood pressure. Circulation. 1954;10:481–90.Google Scholar
- 12.SunTech Medical. Evaluation of a non-invasive blood pressure monitoring technology during emergency transport conditions as compared to the ProPaq LT. Morrisville, NC, USA; 2008. 82-0066-00 rev A.Google Scholar
- 13.Hewlett Packard. An algorithm for reduction of respiratory artifact in pulmonary artery pressure measurements. Application Note; 5953–7352; 1989.Google Scholar
- 16.Muecke S, Bersten AD, Plummer J. The Mean Machine; accurate non-invasive blood pressure measurement in the critically ill patient. J Clin Monit Comp 2009; 23: 283–297.Google Scholar
- 17.Agilent Technologies. Agilent component monitoring system & V24 and V26. Concepts Guide. USA: Agilent Technologies, Inc.; 2000. M1046-9301L.Google Scholar
- 18.AAMI. ANSI/AAMI SP10:2002 & ANSI/AAMI SP10:2002/A1:2003. American National Standard. Manual, electronic, or automated sphygmomanometers; 2002.Google Scholar
- 22.Glantz SA. Primer of biostatistics. 6th ed. USA: McGraw-Hill; 2005.Google Scholar
- 27.Ream AK. Systolic, diastolic, mean or pulse: which is the best measurement of arterial pressure? In: Gravenstein JS, Newbower RS, Ream AK, et al., editors. Essential noninvasive monitoring in anesthesia. USA: Grune & Stratton; 1980. p. 53–74.Google Scholar
- 33.Hansen AT. Pressure measurement in the human organism. Acta Physiol Scand Suppl. 1949;19:11–231.Google Scholar
- 36.Cohn JN, Daddario RC. Mechanism of disappearance of Korotkoff sounds in clinical shock. Circulation. 1965;31–32:69.Google Scholar
- 37.Cohn JN, Luria MH. Studies in clinical shock and hypotension. The value of bedside hemodynamic observations. JAMA. 1964;190:113–8.Google Scholar