Automated sphygmomanometer in spinal cord injured patients during head-up tilt: an evaluation

Fifteen patients with spinal cord injury above T6 who were complete or had sensory sparing only were monitored during head-up tilt to evaluate the clinical application of an indirect blood pressure monitoring device, Vital Signs Measurement System. Comparisons of the machine's auscultatory and oscillometric modes were made to simultaneously auscultated blood pressures obtained by a physician. Mean differences and standard deviations were calculated. The comparison between automatic auscultatory and manual pressures yielded a mean difference and standard deviation of 1.8 mmHg and 4.2 mmHg for systolic, and -0.8 mmHg and 4.9 mmHg for diastolic pressures. The comparison between automatic oscillometric and manual pressures yielded a mean difference and standard deviation of 2.2 mmHg and 7.1 mmHg for systolic, and -12.7 mmHg and 7.5 mmHg for diastolic. All automatically obtained values except oscillometric diastolic pressure indicate machine accuracy suitable for clinical testing when compared to standards set by the Association for the Advancement of Medical Instrumentation for ideal test conditions. Uncontrolled patient or tubing movement, room noise, and the small subject population may have contributed to the less favorable values. This study suggests that the automatic sphygmomanometer tested is capable of clinically acceptable accuracy in a very dynamic setting.