ACCURACY OF PULSE OXIMETRY IN PIGMENTED PATIENTS

Objective, Prospective assessment of the accuracy of three pulse oxime ters and two probe sites in darkly pigmented critically ill patients u nder clinical conditions. Patients and methods. One hundred consecutiv e, darkly pigmented critically ill adult patients with arterial lines in situ were studied, Patients were excluded if the haemoglobin concen tration was less than 7 g/dl and carboxyhaemoglobin or methaemoglobin levels exceeded 2%. Pigmentation was objectively quantified with a por table EEL reflectance spectrophotometer (Evans Electroselenium Company , Diffusion Systems Limited, London). Reflectance was measured at nine wavelengths, Results. The degree of pigmentation as measured by perce ntage reflectance closely matched that of a control group of black Afr icans from a pigmentation study, The limits of agreement (2.6% to 5.8% ), precision and bias values between pulse oximeter and co-oximeter re adings fell within a narrow range. The 95% confidence intervals of the limits of agreement reflected a small variation in the difference bet ween pulse oximeter and co-oximeter readings, These small differences were not clinically significant in the pigmented patients who were enr olled in the study, Conclusion. The accuracy of pulse oximetry is not adversely affected by skin pigmentation, and it remains a useful oxyge nation monitoring device in darkly pigmented patients.