Awareness under Anesthesia in Children

Awareness is the post-operative recall of events that occurs after undergoing general anesthesia. With an incidence of 0.1%-0.2%, it is a rare and well described complication of anesthesia in the adult surgical population (1). Being conscious during surgery is a traumatic event that may lead to adverse psychological consequences, such as post-traumatic stress disorder. Unfortunately, very little is known about awareness during anesthesia in children due to differing anesthesia requirements and techniques. It is possible that the incidence of awareness differs significantly in children, as they have different expectations, fears, and means of managing stressful events, compared to adults. Thus, it may be incorrect to generalize the results of prior studies to the adolescent population (2).

At the Royal Children’s Hospital in Melbourne, Australia, Davidson et al. decided to perform a large, prospective cohort study to determine the incidence of awareness during routine pediatric anesthesia. They interviewed 864 children who had undergone general anesthesia at the aforementioned hospital on 3 different occasions to determine the incidence of awareness. The awareness assessment was nested within a larger study of behavioral change after anesthesia. Reports of suspected awareness were sent to four independent adjudicators. If they all agreed, a case was classified as true awareness. In the end, only twenty eight reports were generated. There were seven cases of true awareness, for an incidence of 0.8%, roughly six to eight times more than in adults (3). No aware child reported distress, and no substantial difference was detected in behavioral disturbance between aware (20%) and non-aware (16%) children.

The authors of this study reported that many features of awareness were similar to those found in studies of adult awareness. For example, they found that the children in the study did not always report the awareness in the first interview. This is consistent with findings in adult studies in which awareness would have been missed if only one interview had been conducted (1). Interestingly, they discovered that none of the children who were aware reported being upset by their memories. Similarly, the incidences of behavioral change and sleep disturbance were similar to those in the non-aware population (2). Given that young children may not have the same degree of understanding of anesthesia as adults, it is quite possible that remembering only noises or voices may be a relatively minor concern compared with a child’s fear of surgery and hospitalization. An adult expects to be unconscious with no memories. A young child may equate anesthesia with sleep and therefore have less faith that he or she will not wake up during the surgery (2).

There are several potential explanations for why awareness may occur in children. Compared to adults, children often require a larger concentration of anesthetic to achieve anesthesia. It is therefore possible that children may be more frequently underdosed. Additionally, the pharmacology of IV anesthetics is also different in children: larger doses are required to produce anesthesia in children (2). In summary, the incidence of awareness during anesthesia in pediatric patients is higher than in adult patients. However, the exact causes of awareness in children remain unclear. Although, none of the children who were aware reported any psychological issues during the study, long-term consequences may arise. Given that awareness does occur in children, further work is needed to examine the causes, consequences, and possibilities of applying new technologies to reduce this incidence.

References

1. Sandin, R. H., Enlund, G., Samuelsson, P. & Lennmarken, C. (2000). Awareness during anaesthesia: a prospective case study. The Lancet, 355(9205), 707-711.
2. Davidson, A., Huang, G., Czarnecki, C., Gibson, M., Stewart, S., Jamsen, K., Stargatt, R. (2005). Awareness during anesthesia in children: a prospective cohort study. Anesthesia & Analgesic, 100(3), 653-661. doi: 10.1213/01.ANE.0000150604.73481.00.
3. Blussé van Oud-Alblas, H., van Dijk, M., Liu, C., Tibboel, D., Klein, J., Weber, F. (2009). Intraoperative awareness during paediatric anaesthesia. British Journal of Anaesthesia, 102(1), 104–110.