A comparison of the effect of three sedatives on esophageal sphincters in cats

Background/Aims: Children 5 years old and younger often require sedation fo r esophageal motility studies (EMS). At our institution, an intramuscular c ocktail of meperidine, promethazine and chlorpromazine (MPC) has been used as the standard sedative for young children undergoing EMS. Administering t he intramuscular sedative may, however, be more traumatic to the child than the procedure. Moreover, its effect on esophageal motility is not known an d prolonged sedation is common. The aim of this study was to determine the effects of MPC and two orally-administered sedatives on esophageal sphincte r function, using the cat model, with a goal to identify a potentially suit able orally-administered sedative for use in young children requiring sedat ion for EMS. Methods: We measured upper (UESP) and lower (LESP) esophageal sphincter pressures in 25 cats initially without sedation, and then followi ng sedation with midazolam, chloral hydrate and MPG. The results were compa red. Results: All three sedatives significantly decreased LESP compared to the control (p<0.05). Midazolam decreased LESP the most; however, the diffe rence from the other sedatives did not reach statistical significance. All three sedatives decreased UESP, compared to control, but the differences we re not statistically significant. Of the two oral sedatives, chloral hydrat e had the least effect on the esophageal sphincters although its effect was not statistically different from that of midazolam. Conclusions: Ethically appropriate studies are needed to determine which oral sedative would be m ost beneficial for use in sedating children undergoing esophageal motility studies. Until studies can be done, the choice between chloral hydrate and midazolam should be based on the experience and comfort of the attending ph ysician with regard to the potential side effects of the medications.