Comparison of pulse oximeters: accuracy at low arterial pressure in volunteers. A laboratory model was developed of limb hypoperfusion in volunteers, using parital occlusion of the brachial artery with consequent reduction in radial artery pulse pressure. This was used to compare the function of 13 pulse oximeters and the effect of reduced pulse pressure and mild hypoxia on these devices. With the exception of one device, all the pulse oximeters studied demonstrated similar accuracies at pulse pressures exceeding 20 mm Hg. There were however, significant differences between several of the pulse oximeters in both ability to display readings and accuracy of readings displayed when brachial artery occlusion reduced radial artery pulse pressures equal to or less than 20 mm Hg. 