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

Children 5 years old and younger often require sedation for esophageal motility studies (EMS). At our institution, an intramuscular cocktail of meperidine, promethazine and chlorpromazine (MPC) has been used as the standard sedative for young children undergoing EMS. Administering the intramuscular sedative may, however, be more traumatic to the child than the procedure. Moreover, its effect on esophageal motility is not known and prolonged sedation is common. The aim of this study was to determine the effects of MPC and two orally-administered sedatives on esophageal sphincter function, using the cat model, with a goal to identify a potentially suitable orally-administered sedative for use in young children requiring sedation for EMS.

We measured upper (UESP) and lower (LESP) esophageal sphincter pressures in 25 cats initially without sedation, and then following sedation with midazolam, chloral hydrate and MPC. The results were compared.

All three sedatives significantly decreased LESP compared to the control (p<0.05). Midazolam decreased LESP the most; however, the difference from the other sedatives did not reach statistical significance. All three sedatives decreased UESP, compared to control, but the differences were not statistically significant. Of the two oral sedatives, chloral hydrate had the least effect on the esophageal sphincters although its effect was not statistically different from that of midazolam.

Ethically appropriate studies are needed to determine which oral sedative would be most 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 physician with regard to the potential side effects of the medications.