Comparison of 2-channel and 4-channel pneumograms.

To determine whether the addition of air flow and O2 saturation (SaO2) channels improves sensitivity of the pneumogram in identifying cardiorespiratory pattern abnormalities, 2- and 4-channel pneumograms (PG-2 and PG-4) were simultaneously recorded in 91 consecutive infants. Forty-one infants (45%) had cardiorespiratory symptoms, and 50 were asymptomatic. Pneumograms were considered abnormal for any of the following: apnea greater than or equal to 20 seconds, heart rate less than 80 bpm for greater than 5 seconds in preterm and less than 60 bpm in full-term infants (bradycardia), shorter apnea with bradycardia or desaturation, periodic breathing greater than 7% of total sleep time in preterm and greater than 4% in full-term infants, or SaO2 less than 85% for greater than 5 seconds. Both recordings were normal in 72% of infants and abnormal in 24%. In only 4% were the PG-4 abnormal when the PG-2 were normal, in all instances due to minimum SaO2 levels of 77-84% for 5-19 seconds associated with central apnea of intermediate duration (three infants) or with mixed apnea. The difference in frequency of abnormal results between the PG-2 and PG-4 recordings was not statistically significant (X2). In conclusion, although PG-4 do increase the scope of physiological information obtained in infants with cardiorespiratory events, this short-term study does not establish whether this increase results in any long-term benefits. Further, at least in this number and these types of at-risk infants, PG-4 do not improve the sensitivity of cardiorespiratory recordings for detecting abnormalities.