Interventions at caesarean section for reducing the risk of aspiration pneumonitis

Abstract

Background Aspiration pneumonitis is a syndrome resulting from the inhalation of gastric contents. The incidence in obstetric anaesthesia has fallen, largely due to improved anaesthetic techniques and the increased use of regional anaesthesia at caesarean section. However, aspiration pneumonitis is still a cause of maternal morbidity and mortality, and it is important to use effective prophylaxis. Objectives To determine whether interventions given prior to caesarean section reduce the risk of aspiration pneumonitis in women with an uncomplicated pregnancy. Search methods We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register (April 2009). Selection criteria Randomised controlled trials were included. Quasi-randomised trials were excluded. Data collection and analysis Authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Data entry was checked. Main results Twenty-two studies, involving 2658 women, are included, all having a caesarean section under general anaesthesia. The studies covered a number of comparisons, but were mostly small and of unclear or poor quality. When compared to no treatment or placebo, there was a significant reduction in the risk of intragastric pH < 2.5 with antacids (risk ratio (RR) 0.17, 95% confidence interval (CI) 0.09 to 0.32, two studies, 108 women), H2 antagonists (RR 0.09, 95% CI 0.05 to 0.18, two studies, 170 women) and proton pump antagonists (RR 0.26, 95% CI 0.14 to 0.46, one study 80 women). H2 antagonists were associated with a reduced the risk of intragastric pH < 2.5 at intubation when compared with proton pump antagonists (RR 0.39, 95% CI 0.16 to 0.97, one study, 120 women), but compared with antacids the findings were unclear. The combined use of ’antacids plus H2 antagonists’ was associated with a significant reduction in the risk of intragastric pH < 2.5 at intubation when compared with placebo (RR 0.02, 95% CI 0.00 to 0.15, one study, 89 women) or compared with antacids alone (RR 0.12, 95% CI 0.02 to 0.92, one study, 119 women). Authors’ conclusions The quality of the evidence was poor, but the findings suggest that the combination of antacids plus H2 antagonists was more effective than no intervention, and superior to antacids alone in preventing low gastric pH. However, none of the studies assessed potential adverse effects or substantive clinical outcomes. These findings are relevant for all women undergoing caesarean section under general anaesthesia.

The effect of various pre-cesarean fasting times on maternal and neonatal outcomes

“…Currently, most cesarean sections are performed under local anesthesia and with appropriate techniques, so the incidence of aspiration pneumonitis syndrome is reduced. [ 18 ] It should be noted that water exits the stomach within 12 min and carbohydrate drinks are not present in the stomach 90 min after drinking. [ 5 ] Ultrasound examination also showed that gastric emptying was normal during pregnancy and decreased only slightly at the onset of labor.…”

General anesthesia in the parturient

“…The prophylactic use of antacids, H2-receptor antagonists, proton pump inhibitors (PPIs), and prokinetic drugs aims to reduce the volume and increase the pH of gastric contents and minimize the risk of regurgitation and aspiration. A combination of prophylactic agents might be more effective than single medication 37…”

“…Metoclopramide 10 mg IV can be used in addition to H2-receptor antagonists or PPIs, but it is more effective as an antiemetic 43. Nonparticulate antacids such as sodium citrate (30 mL) increase gastric pH immediately and for ∼1 hour and therefore should be administered shortly before induction of GA 37,44,45…”