Background Cerebral autoregulation (CA) is a physiologic mechanism ensuring constant blood flow to the brain independent of changes (within physiological limits) in mean systemic blood pressures. Compromised CA can lead to ischemia, associated with hypoxic injury and long term sequelae. The efficiency of CA in neonates is not well-known, especially during general anaesthesia. We aimed to determine incidences of significant cerebral desaturation (ScO2).
Methods Observational data were collected from 33 premature and term neonates (up to post-menstrual age 44 weeks), receiving general anaesthesia for surgery. Near- infrared spectroscopy (ForeSight® CerebralOximeter, CASMED, USA) was used to noninvasively measure regional ScO2. When used, invasive arterial pressures were recorded electronically. We then calculated the cerebral oximeter index (COx), to estimate adequacy of autoregulation. The lowest mean arterial pressure at which the COx was 1,2
Results Incidence of cerebral desaturations across the patient population was 30.3%(n = 10). Very premature neonates with severe haemodynamic instabilities undergoing surgery presented greater depressions in ScO2. Additionally they showed evidence of impaired autoregulation compared to hemodynamically stable neonates. Incidence of loss of CA according to COx was 33% (n = 11) in this patient group.
Discussion Results obtained demonstrate that sick neonates are more prone to decreased ScO2. Further research, with a bigger patient population is needed to determine the incidence more accurately, and its significance and consequences for outcome of these findings.
Joshi et al. Anesth Analg 2012;114:503–510
Brady et al. Stroke 2007;38:2818–2825