Prehospital blood pressures: inaccuracies caused by ambulance noise?

Am J Emerg Med. 1994 Nov;12(6):617-20. doi: 10.1016/0735-6757(94)90025-6.


Blood pressure measurements in a moving ambulance can be difficult to obtain. Sirens, engine noise, and road noise can all interfere with the accurate detection of a patient's blood pressure. This study was undertaken to determine the influence of ambulance noise and vibration on auscultated blood pressures. A model was developed that used dynamic pressures to simulate systolic Korotkoff sounds. Forty-nine emergency personnel were asked to obtain blood pressures using the model in both a quiet environment and in a moving ambulance. A total of 485 blood pressure measurements were obtained. Systolic pressures were randomized to two settings: 76 mm Hg and 138 mm Hg. Stationary readings were compared with moving readings using analysis of variance for repeated measures. Systolic blood pressure measurements obtained in the quiet environment averaged 133 +/- 5 mm Hg at the high setting, and 45 +/- 6 mm Hg at the low setting. Systolic blood pressure measurements obtained in a moving ambulance averaged 86 +/- 7 mm Hg at the high setting, and 41 +/- 7 mm Hg at the low setting. The average differences between quiet and moving measurements were 47 mm Hg at the "high" setting (P < .01) and 4 mm Hg at the "low" setting (P > .01). At physiological levels, blood pressures obtained in moving ambulances differ significantly from those obtained in a quiet environment, which may be caused by road noise and ambulance motion.

Publication types

  • Clinical Trial
  • Comparative Study
  • Controlled Clinical Trial

MeSH terms

  • Ambulances*
  • Auscultation
  • Bias
  • Blood Pressure Determination / methods*
  • Emergency Medical Services / methods*
  • Evaluation Studies as Topic
  • Heart Sounds
  • Humans
  • Models, Cardiovascular
  • Noise, Transportation*
  • Reproducibility of Results
  • Systole
  • Vibration