Clinical significance of nocturnal oximeter monitoring for detection of sleep apnea syndrome in the elderly.
OBJECTIVE
The sensitivity and specificity of overnight monitoring of arterial oxygen saturation (SaO(2)) using an oximeter were evaluated in elderly subjects who are being investigated for possible sleep apnea syndrome (SAS).


METHODS
Seventy-five consecutive elderly subjects with habitual snoring (47 men, 28 women; mean (+/-SE) age 75.5+/-0.9 years (range 65-94 years)) were studied. The SaO(2) was measured with an oximeter and a chart recorder during the night immediately before detailed polysomnographic studies. The SaO(2) recordings were classified by two observers as positive or negative using a number of significant oxyhemoglobin desaturation (SDS) of more than 2, 4, and 6%. The sensitivity of the oximeter alone for the recognition of the SAS was calculated as the number of true positive SaO(2) records divided by the total number of positive definitive (polysomnographic) records. The specificity was defined as the number of true negative SaO(2) records divided by the total number of negative definitive records.


RESULTS
Of the 75 subjects, 24 had moderate SAS (apnea index (AI)>15) and 55 had mild to moderate SAS (AI>5). The sensitivity and specificity of the dosimeter as a screening test were determined with the two diagnostic thresholds of the AI. For AI exceeding 5 or 15, the respective sensitivity by using the criterion of SDS of more than 4% was 85.5 or 91.7%, with corresponding specificity of 85.0 or 92.2%.


CONCLUSIONS
The nocturnal oximeter monitoring allows recognition of elderly subjects with a mild to moderate SAS, and 4% desaturation of SaO(2) is a candidate index to detect a significant number of apneas in elderly SAS patients with an oximeter.
Teramoto
Shinji
S
San-no Hospital, International University of Health and Welfare, 8-10-16, Akasaka, Minato-ku, Tokyo 107-0052, Japan. shinji-tky@umin.ac.jp
Matsuse
Takeshi
T
Fukuchi
Yoshinosuke
Y