Journal of clinical monitoring
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The natural frequencies, damping coefficients, and accuracies of umbilical artery catheters were determined. The damping coefficients for the 3.5, 5.0, and 8.0 French catheters were 0.40 +/- 0.04 (mean +/- SD), 0.42 +/- 0.05, and 0.19 +/- 0.02, respectively. ⋯ Measurements obtained with 3.5 and 8.0 French catheters were within 6% of the reference pressure at all pressures and rates tested. With the 5.0 French catheter, however, error greater than 10% from the reference pressure occurred when the rate was 200 pulses per minute or greater and the applied maximum pressure was 100 mm Hg or more.
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Comparative Study
Comparison of radial and femoral arterial blood pressures in children after cardiopulmonary bypass.
We compared radial and femoral arterial blood pressures in 29 patients, ranging in age from 1.25 to 17 years, during and after cardiopulmonary bypass for repair of congenital heart disease. Radial mean arterial pressure (MAP) was more than 10% lower than femoral MAP in 17 patients (58%), and in 7 of these patients (24%) radial MAP was more than 20% lower than femoral MAP. ⋯ We found no correlation between femoral-minus-radial pressure difference and postoperative course. These data demonstrate that radial arterial pressure may be misleadingly low in children undergoing operation for correction of congenital cardiac defects.
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A pulse oximeter was compared with an ear oximeter for measurement of arterial hemoglobin saturation within the range of 70 to 100% in 11 healthy volunteer subjects. Two hundred seventy-seven pooled data points were obtained, and analysis was performed by means of linear regression. The accuracy was 3% (95% confidence limits). ⋯ The pulse oximeter was easy to use because, unlike the ear oximeter, it required no time-consuming instrument calibration or site preparation. In addition, the delays involved in taking an invasive sample, transporting it to the blood gas laboratory, and waiting for the results were eliminated. Saturation values were continually available, and placement and use of the pulse oximeter sensor caused no discomfort to the volunteer subjects.