The all-night polysomnogram is used to assess the severity of sleep apnea by the quantitative analysis of a number of respiratory and sleep parameters. Because precise scoring of these parameters is a time-consuming process, we studied the effect of scoring varying percentages of polysomnograms on the accuracy of estimating sleep apnea severity. Twenty adult all-night polysomnograms with apnea-hypopnea (AH) indexes ranging from 1.0 to 67.8 were scored in the following manner: every 30-s epoch (100% scoring), every other epoch (50% scoring), every fourth epoch (25% scoring), every sixth epoch (16.7% scoring), every eight epoch (12.5% scoring), and every tenth epoch (10% scoring). Each method was then compared with 100% scoring. For each parameter we established criteria for classifying studies as having a mild, moderate, or severe degree of abnormality. The number of studies correctly categorized for the following parameters was: (1) AH index, 20/20 for 50 and 25% scoring, 19/20 for 16.7 and 10% scoring, and 18/20 for 12.5% scoring; (2) AH time, 20/20 for 50, 25, and 16.7% scoring, 17/20 for 12.5% scoring, and 18/20 for 10% scoring; (3) mean AH duration, 20/20 for 50, 25, and 12.5% scoring, 18/20 for 16.7% scoring, and 15/20 for 10% scoring; (4) mean event percent O2 saturation, 20/20 for 50 and 25% scoring, 18/20 for 16.7 and 12.5% scoring, and 17/20 for 10% scoring; (5) longest AH, 19/20 for 50% scoring, 18/20 for 25% scoring, and 15/20 or less for 16.7, 12.5, and 10% scoring; (6) lowest percent O2 saturation, 19/20 for 50% scoring, 17/20 for 25% scoring, and 15/20 or less for 16.7, 12.5, and 10% scoring. The correlation coefficients (r) of the mean sleep stage percentages and mean sleep efficiency indexes of the 20 polysomnograms for all 5 levels of scoring compared with 100% scoring were greater than 0.94. We conclude that scoring by sampling is a highly accurate method for estimating AH index, AH time, mean AH duration, mean event percent O2 saturation, sleep efficiency index, and for sleep stage quantification. It is less accurate for identifying isolated events such as the longest respiratory event duration and the lowest percent O2 saturation.
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine