title: Gastric emptying of water in term pregnancy.
abstract: BACKGROUND
  Healthy nonpregnant patients may ingest clear liquids until 2 h before induction of anesthesia without adversely affecting gastric volume. The purpose of this study was to compare gastric emptying in term, nonlaboring pregnant women after ingestion of 50 ml water (control) with that after ingestion of 300 ml water.
  
  
  METHODS
  Gastric emptying was assessed in healthy, nonobese, term pregnant volunteers using both serial gastric ultrasound examinations (n = 9) and acetaminophen absorption (n = 11) in a crossover study design. After an overnight fast, volunteers ingested 1.5 g acetaminophen and 50 or 300 ml water (assigned in random order) on two occasions separated by at least 2 days. Serial gastric antrum cross-sectional areas were determined using gastric ultrasound imaging, and the half-time to gastric emptying was calculated. Serial plasma acetaminophen concentrations were measured. Areas under the plasma acetaminophen concentration versus time curve, peak concentrations, and time to peak concentration for 50- and 300-ml ingestions were compared.
  
  
  RESULTS
  Gastric emptying half-time was significantly shorter after ingestion of 300 ml water than after ingestion of 50 ml (24 +/- 6 vs. 33 +/- 8 min). There were no differences in acetaminophen areas under the curve at 60, 90, or 120 min, or in acetaminophen peak concentration. Time to peak concentration of acetaminophen was significantly shorter after ingestion of 300 ml water than after ingestion of 50 ml (25 +/- 12 vs. 41 +/- 19 min).
  
  
  CONCLUSIONS
  Gastric emptying in healthy, term, nonobese, nonlaboring pregnant women is not delayed after ingestion of 300 ml water compared with that after an overnight fast.
authors.affiliation: Department of Anesthesiology, Northwestern University Medical School, Chicago, Illinois 60611, USA. c-wong2@northwestern.edu
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Wong
authors.forename: Mariann
authors.initials: M
authors.lastname: Loffredi
authors.forename: Jeanne N
authors.initials: JN
authors.lastname: Ganchiff
authors.forename: Jia
authors.initials: J
authors.lastname: Zhao
authors.forename: Zhao
authors.initials: Z
authors.lastname: Wang
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Avram
mesh_terms: D000082:Acetaminophen / Q000493:pharmacokinetics; D000328:Adult; D001834:Body Water / Q000378:metabolism*; D018592:Cross-Over Studies; D005260:Female; D005746:Gastric Emptying; D006801:Humans; D011247:Pregnancy / Q000378:metabolism*
chemical_list: D000082:Acetaminophen