Gastric emptying and feeding in labour

NPO during labor. Is there any scientific validation?

Maternal death from pulmonary aspiration of gastric contents has virtually disappeared in the United Kingdom. The one case documented in the most recent triennial report was a woman with multiorgan failure in intensive care and is probably not relevant to the current debate [1]. Although not so well documented, other Western countries seem to be experiencing the same decline in maternal death from this cause. At the same time, the burden of proof is falling increasingly on obstetric anesthesiologists as obstetricians and midwives demand that NPO policies should be rejected, unless anesthesiologists can prove that they are necessary. Without any proof of benefit, many midwives actively encourage eating in women who do not really want to eat. A hospital manager who wants to divert money to other areas of health care might make the same argument about employing less experienced--and therefore cheaper--anesthesiologists or nurse anesthetists on the labor floor. Although no self-respecting obstetric anesthesiologist would accept such a situation, there is still no randomized controlled trial that proves that experienced anesthesiologists reduce maternal mortality. Similarly it is difficult for a mother to comprehend the negligible risk of pulmonary aspiration during labor while her care providers insist that it would be more dangerous for her to cross a busy road! Against a background of conflicting advice from midwives and medical practitioners, the mother is likely to eat if she feels so inclined. Pulmonary aspiration is a rare complication, so even if a light diet in labor became acceptable, it is likely that it would take many years for a subsequent increase in maternal mortality to become apparent. It would be disappointing if mistakes made by a previous generation had to be relearned in the twenty-first century. Increasingly, media-controlled pressure groups dictate health fashions, and the physicians frequently can only stand on the sidelines and advise. Most obstetric anesthesiologists agree that a rigid NPO policy in labor is no longer appropriate and that at least water or ice chips should be allowed. Current evidence suggests that solids and semi-solids should be avoided once a woman is in active labor or requests analgesia. The appropriate advice is to allow a carefully audited introduction of isotonic drinks. These drinks seem to be an effective medium for providing calories while minimizing any increase in gastric volume, and such a policy would be unlikely to reverse the reduction in aspiration that has been achieved over the past 50 years.

Eating in labour. A randomised controlled trial assessing the risks and benefits

The aim of this study was to determine whether permitting women in labour to eat a light diet would: (i) alter their metabolic profile, (ii) influence the outcome of labour, and (iii) increase residual gastric volume and consequent risk of pulmonary aspiration. Women were randomised to receive either a light diet (eating group, n = 48) or water only (starved group, n = 46) during labour. The light diet prevented the rise in plasma beta-hydroxybutyrate (p = 2.3 x 10(-5)) and nonesterified fatty acids (p = 9.3 x 10(-7)) seen in the starved group. Plasma glucose (p = 0.003) and insulin (p = 0.017) rose in the eating group but there was no difference in plasma lactate (p = 0.167) between the groups. There were no differences between the groups with respect to duration of first or second stage of labour, oxytocin requirements, mode of delivery, Apgar scores or umbilical artery and venous blood samples. Relative gastric volumes estimated by ultrasound measurement of gastric antral cross-sectional area were larger (p = 0.001) in the eating group. This was supported by the observation that those from this group who vomited, vomited significantly larger volumes than those in the starved group (p = 0.001). We conclude that eating in labour prevents the development of ketosis but significantly increases residual gastric volume.