A clinical evaluation of the accuracy of the Nellcor N-100 and Ohmeda 3700 pulse oximeters.

Two pulse oximeters, the Nellcor N-100 and the Ohmeda 3700, were compared with arterial blood values and with each other in a clinical evaluation of performance. Three hundred twenty-nine simultaneously sampled blood/oximeter data pairs from use of both makes of pulse oximeters on each of 152 test subjects were included in the comparison analysis for each oximeter. Among the patients, disease type and severity and hospital location varied widely. Basic descriptive statistics and linear regression analysis were employed to facilitate comparison. Both oximeters displayed a statistically significant but clinically insignificant bias when compared with arterial blood oxyhemoglobin: -0.31 (P = 0.023) and 0.59 (P = 0.001) for the Ohmeda 3700 pulse oximeter and the Nellcor N-100 pulse oximeter, respectively. Relative to arterial blood oxyhemoglobin, the 95% tolerance intervals were +4.84 to -5.45 (10.3) for the Ohmeda 3700 and +6.94 to -5.76 (12.7) for the Nellcor N-100. Regressed against [oxyhemoglobin + carboxyhemoglobin + methemoglobin] as x, the Nellcor N-100 read y = 0.85(x) + 12.5, r = 0.83, P less than 0.0001, and the Ohmeda 3700 read y = 1.02(x) - 5.3, r = 0.86, P less than 0.0001.