Compromised infant are most Affected by GeneralAnesthesia for CesareanDelivery

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Infants With Fetal Distress Are Most Affected by General Anesthesia for Cesarean Delivery

May 4, 2009 — The infants most affected by general anesthesia for cesarean delivery are those who are already compromised in utero, according to the results of a study reported in the April 29 Online First issue of BMC Medicine.

"Anaesthesia guidelines recommend regional anaesthesia for most caesarean sections due to the risk of failed intubation and aspiration with general anaesthesia," write Charles S. Algert, from Kolling Institute of Medical Research, University of Sydney in Sydney, Australia, and colleagues. "However, general anaesthesia is considered to be safe for the foetus, based on limited evidence, and is still used for caesarean sections."

The study cohort consisted of 50,806 infants delivered by cesarean delivery from 1998 to 2004 for indications of planned subsequent cesarean delivery, failure to progress, or fetal distress. The investigators compared outcomes of neonatal intubation and 5-minute Apgar scores of less than 7 for deliveries performed with the mother under general anesthesia vs those performed with the mother under spinal or epidural anesthesia.

For all 3 indications and across all levels of hospital, the risk for adverse outcomes was increased for cesarean deliveries performed with the patient under general anesthesia. Low-risk, planned subsequent cesarean deliveries had the largest relative risks for resuscitation with intubation (relative risk, 12.8; 95% confidence interval [CI], 7.6 - 21.7), and for Apgar scores of less than 7 (relative risk, 13.4; 95% CI, 9.2 - 19.4). Unplanned cesarean deliveries because of fetal distress had the largest absolute increase in risk (5 extra intubations per 100 deliveries and 6 extra Apgar scores < 7 per 100 deliveries).

"The infants most affected by general anaesthesia were those already compromised in utero, as evidenced by foetal distress," the study authors write. "The increased rate of adverse neonatal outcomes should be weighed up when general anaesthesia is under consideration."

A limitation of this study is that infant records were only available up to separation from the birth hospital, so longer-term outcome data were not available.

"The increased rates of neonatal intubation after GA [general anesthesia] in this study represent harm in and of itself, and the persistence of low 5-minute Apgar scores suggests that deleterious effects may last longer than the immediate aftermath of delivery," the study authors conclude. "The greatest absolute increase in the rate of intubation and of a 5-minute Apgar score <7 for deliveries performed under GA occurred in the most vulnerable infants: those that were delivered by emergency CS [cesarean section] because of foetal distress. Clinicians considering the use of GA for a CS delivery should be aware of these possible consequences for the infant, for both planned and emergency CS."

The Australian National Health and Medical Research Council supported this study. The study authors have disclosed no relevant financial relationships.
BMC Med. Published online April 29, 2009.

Clinical Context
Current guidelines recommend regional anesthesia as the first option for cesarean delivery, and this is primarily because of concern regarding the risk for failed endotracheal intubation and aspiration of gastric contents among women in labor. However, at least 1 review of randomized trials has questioned whether regional anesthesia truly promotes better neonatal outcomes vs general anesthesia.
The current study uses a large birth registry to compare regional anesthesia vs general anesthesia during cesarean delivery. Researchers specifically examined the relative risk for fetal distress.

Clinical Implications

• The main concern with general anesthesia for cesarean delivery is the risk for failed endotracheal intubation and aspiration of gastric contents among women in labor.
• In the current study, general anesthesia for cesarean delivery was associated with higher risks for intubation of the infant and low Apgar scores vs regional anesthesia. This finding was independent of the indication for cesarean delivery and the type of hospital in which the delivery was performed.