Influence of halothane, isoflurane, and sevoflurane on gastroesophageal reflux during anesthesia in dogs.
OBJECTIVE
To determine whether maintenance of anesthesia with halothane or sevoflurane is associated with a lower incidence of gastroesophageal reflux (GER) than the use of isoflurane in dogs undergoing orthopedic surgery.


METHODS
90 dogs.


METHODS
Dogs were evaluated during elective orthopedic surgery. Dogs with a history of vomiting or that had received any drugs that would alter gastrointestinal tract function were excluded from the study. The anesthetic protocol used was standardized to include administration of acepromazine maleate and morphine prior to induction of anesthesia with thiopental. Dogs were allocated to receive halothane, isoflurane, or sevoflurane to maintain anesthesia. A sensor-tipped catheter was placed to measure esophageal pH during anesthesia. Gastroesophageal reflux was defined as an esophageal pH < 4 or > 7.5.


RESULTS
51 dogs had 1 or more episodes of acidic GER during anesthesia. Reflux was detected in 14 dogs receiving isoflurane, 19 dogs receiving halothane, and 18 dogs receiving sevoflurane. In dogs with GER, mean +/- SD time from probe placement to onset of GER was 36 +/- 65 minutes and esophageal pH remained < 4 for a mean of 64% of the measurement period. There was no significant association between GER and start of surgery or moving a dog on or off the surgery table. Dogs that developed GER soon after induction of anesthesia were more likely to regurgitate.


CONCLUSIONS
Maintenance of anesthesia with any of the 3 commonly used inhalant agents is associated with a similar risk for development of GER in dogs.
Wilson
Deborah V
DV
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA.
Boruta
Daniel T
DT
Evans
A Tom
AT
D018685:Anesthetics, Inhalation / Q000009:adverse effects*; D000818:Animals; D004283:Dog Diseases / Q000209:etiology*; D004285:Dogs; D005764:Gastroesophageal Reflux / Q000209:etiology / Q000662:veterinary*; D006221:Halothane / Q000009:adverse effects; D006863:Hydrogen-Ion Concentration; D007530:Isoflurane / Q000009:adverse effects; D008738:Methyl Ethers / Q000009:adverse effects; D019637:Orthopedic Procedures / Q000662:veterinary*; D012307:Risk Factors; D000077149:Sevoflurane
D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D007530:Isoflurane; D006221:Halothane