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A1130
October 24, 2015
10:00:00 AM - 12:00:00 PM
Room Hall B2-Area E
A Review of Fasting and the Risk of Aspiration in Labour
Christopher Harty, B.S.N., Erin Sproul, B.S.N., Michael J. Bautista, M.D., FRCPC, Andrew E. Major, M.D., Alison Farrell, Not Applicable
Memorial University Faculty of Medicine, St. John's, Newfoundland and Labrador , Canada
Disclosures: C. Harty: F. Funded Research; Self; $2500 CAD in Student Research Grants. E. Sproul: F. Funded Research; Self; 2500. M.J. Bautista: None. A.E. Major: None. A. Farrell: None.
Introduction: Controversy exists regarding oral intake in parturients despite longstanding belief that they are at increased risk of aspiration. Since Mendelson’s 1946 study addressing the morbidity and mortality associated with aspiration, strict NPO (nothing by mouth) policies during labour have been widely implemented (1). This review explores the risk of aspiration in labour, determines if gastric emptying is delayed in pregnancy or labour, identifies potential medications to improve gastric emptying, and outlines the effect of fasting on labouring women. This evidence-based information can then be used to properly critique potentially outdated NPO policies.

Methods: CINAHL, PubMed, Cochrane and Embase databases searched using keyword and MeSH terms relevant to search topics. Searches yielded 7,515 articles in total, which were de-duplicated and subsequently eliminated by title and abstract with specific inclusion and exclusion criteria. Inclusion criteria comprised all study types and expert opinion, English articles, and specified the study population as laboring women with in-hospital delivery by physician. Exclusion criteria included news articles, non-adult aspiration pneumonitis, and articles focusing on neonates. Review articles before 1990 were excluded and 385 articles were included in the review.

Results/Discussion: Declining rates of parturient aspiration mortality have been indicated in the UK with no reported cases from 2000-2005 when compared with rates of 1.499 per 1000 parturients during the 1940s (2). This change appears owed to increased neuraxial anesthetic use, improved anesthetist training and laryngeal mask airway usage for failed intubations (2). Failed intubation presents the most significant contribution to aspiration, while co-morbidities such as obesity, pre-eclampsia and eclampsia are other risk factors (3). Literature supports early epidural catheter placement for patients displaying these risk factors (3). Fasting in labour appears to produce adverse metabolic effects leading to unnecessary stress and production of ketones (4). It is shown to initially decrease gastric volume, yet women continue to secrete gastric juices of low pH, potentially increasing morbidity and mortality should aspiration occur (5). There is consensus that delayed gastric emptying occurs during labour while literature is conflicting regarding gastric emptying delay in pregnancy. Literature outlines that opiates cause significant delays in gastric emptying (3). There is support in the use of PPIs and H2 receptor antagonists to increase the pH of gastric contents where metoclopramide may also be administered prior to delivery to improve gastric emptying in the parturient (5).

Conclusion: This review suggests that in low-risk patients with no risk factors, fasting does not appear warranted. As parturient aspiration rates are nearly extinct due to advancements in anesthesia practice, identification of high-risk populations becomes essential. Early epidural placement in patients with pre-eclampsia, eclampsia, and obese patients is suggested. Administration of PPI, H2 receptor antagonists, and metoclopramide improve gastric acidity. Opiates delay gastric emptying and fasting at the point of their administration is a reasonable consideration. Further research in prevention of opioid effects on delayed gastric emptying is warranted.

References 

1) J Midwifery Wom Heal 2008 53: 276-283

2) Brit Med J 2009 338: 784.

3) Anaesth Intensive Care Med 2013 14: 346-349.

4) Int Anesthesiol Clin 2007 45: 133-147

5) Eur J Obstet Gyn R B 2009, 146, 3-7

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