Study on cortical arousal at voiding in term and preterm newborns monitored by electroencephalogram

Abstract

Objective To investigate the voiding patterns of term and preterm newborns and whether voiding in term and preterm neonates was accompanied by any cortical arousal. Methods Between May 2013 and September 2013, 64 hospitalized newborns at Neonatal Intensive Cave Unit in the Frist Affiliated Hospital of Zhengzhou University were recruited in this study.In these patients, 31 cases were term newborns (20 male, 11 female) and 33 cases were preterm newborns(19 male, 14 female). The term and preterm newborns gestational ages at birth were(38.2±1.2) weeks and (32.1±1.6) weeks, weighted (3.3±0.4) kg and(1.7±0.3) kg, respectively and postnatal ages at study were[4-16(10.5±3.6)] days and [4-16(11.2±3.1)] days.The voiding volume (VV), post-void residual volumes(PRV), body movement rate and voiding frequency (VF) in 4 hours as well as the volume of milk and liquid fed at the same time frame were recorded and analyzed, retrospectively.At the same time electrocardiogram (ECG) and electroencephalogram (EEG) were recorded.The changes of heart rate (HR), EEG frequency, respiratory frequency (RF) during the 5 s period and 30 s before and after voiding onset were compared respectively.For cortical arousal definition the recommendations of the International Pediatric Work Group on Arousals (2005) were used. Results A total of 184 times of voiding were recorded.In preterm newborns, the VV and body movements rate were significantly lower compared with the term newborns[(21.8±7.9) mL and (41±21)% vs (26.4±8.7) mL and (62±19)%, t=3.75, 4.20, all P<0.05]. However, the VF and PRV were significantly higher in preterm newborns[(1.7±0.9) mL and (3.2±1.1) times vs (1.2±0.7) mL and (2.6±0.9) times, t=2.47, 2.38, all P<0.05]. Bladder voiding in these infants happened only during QS.In term newborns, HR frequency was higher during the 5 s interval before and after voiding onset when compared with the 30 s period before voiding onset[(152±6) times/min and (152±5) times/min vs (147±6) times/min, t=5.30, 5.76, all P<0.05] and the EEG frequency[(2.6±0.1) Hz and (2.6±0.1) Hz vs (1.5±0.1) Hz, t=70.0, 70.0, all P<0.05]. While the HR and EEG frequency of preterm neonate was not changed before and after bladder voiding onset.The RF of both term and preterm neonates were not changed before and after bladder voiding onset. Conclusions The voiding patterns between term and preterm were significantly different and cortical arousal was found only in term neonates, which indicate the term newborns have better mature bladder function and development of nervous system. Key words: Infant, newborn; Voiding; Cortical arousal