SLEEP STATE, CARDIORESPIRATORY AND ELECTROCORTICAL ACTIVITY IN INFANTS WITH TRANSPOSITION OF GREAT-VESSELS

Objectives Sleep states and physiological changes during sleep may be useful in assessing brain function. We hypothesized that infants with transposition of great Vessels (TGV) exhibit recognizable states of sl eep under conditions of isocapnic hypoxemia. Also, we speculated that early correction of hypoxemia may result in significant changes in the physiological characteristics of quiet and active sleep. Methods Six- hour continuous cardiorespiratory and electrocortical recordings were performed in five term infants with TGV, pre- and postoperatively alon g with simultaneous minute by minute behavioral sleep state assignment . Data were sorted for sleep states and percent sleep time for each st ate was computed. Measurements of state-dependent variables, i.e., hea rt Fate (HR), heart Fate variability (HRSD), respiratory frequency (f) , variability in respiratory frequency (fSD), and spectral properties of the EEG during quiet and active sleep were compared for both pre- a nd postoperative periods. Results All infants showed significant diffe rences in state-dependent Variables between quiet and active sleep, bo th during preoperative (mean O-2 saturation = 80.9 +/- 2.8) and postop erative (mean O-2 saturation = 92.8 +/- 0.5) periods. As compared to p reoperative period, postoperatively during quiet sleep, Up and HRSD we re lower, and EEC power was greater; and during active sleep, Up, HRSD , and fSD decreased and EEC power increased. Also, in the postoperativ e period % quiet sleep increased and % active sleep decreased. Conclus ions Under conditions of isocapnic hypoxemia infants with TGV vessels exhibit clearly recognizable states of sleep. Correction of hypoxemia is associated with significant changes in state-dependent Variables bo th during quiet and active sleep.