pseudoephedrine prophylaxis for prevention of middle ear barotrauma in hyperbaric oxygen therapy

Conditions: Barotrauma;Ear

Summary: hyperbaric oxygen therapy (hbot) utilizes 100% oxygen delivery at a pressure greater than 1 atm for the treatment of various emergent medical conditions including carbon monoxide poisoning. the most commonly associated complication of hbot is middle ear barotrauma (meb) which occurs when the eustachian tube does not allow air to enter the middle ear space to equalize the pressure between the ambient environment and the inner ear. patients experiencing meb usually feel pressure or pain in their ear(s). the spectrum of symptoms ranges from sensation of ear fullness and muffled hearing to severe pain, vertigo and tympanic membrane rupture. the incidence of meb, depending on the definition used is between 2-45%. the severe discomfort associated with meb sometimes causes hbot to be postponed or abandoned. last year 27/991 treatments at our center for hyperbaric and dive medicine were aborted due to meb. currently there is no objective criteria for predicting which patients will experience these complications, nor is there consensus on effective prevention measures. at our facility, oxymetazoline, a topical nasal decongestant, is the standard rescue medication administered for patients that have symptoms of meb during hbot. this is despite two negative studies showing that this medication does not work any better than placebo. other studies involving scuba divers and airplane travelers showed that oral pseudoephedrine is effective in decreasing meb. however, the use of pseudoephedrine for patients undergoing hbot has not been studied. the investigators plan to perform a randomized double blind placebo control trial to determine if pseudoephedrine is effective in decreasing the rate of meb during hbot.

aim 1: to investigate the efficacy of pre-treatment with oral pseudoephedrine 60mg for decreasing meb during hbot. hypothesis: patients randomized to pseudoephedrine will have a lesser need for oxymetazoline rescue therapy while being compressed. they will also report less ear pain once at pressure compared to patients receiving placebo. aim 2: to measure the incidence of meb during hbot. the investigators will also identify factors (age, gender, medical history) that could predispose an individual to developing meb during hbot. hypothesis: the incidence of meb defined as requiring stopping compression of the chamber and oxymetazoline rescue will be greater than 30%. female sex, age above 60, and prior history of ear conditions will be associated with development of meb.

Eligibility criteria:
inclusion criteria: * new patient requiring hbot (either inpatient or outpatient) * age greater than or equal to 18 years and less than 80 years * fluent in english * full decision capacity * able and medically cleared to swallow a pill exclusion criteria: * contraindication to pseudoephedrine (maoi use, pregnancy, glaucoma, heart disease, allergy to drug class) * sbp \>160 * dbp \> 90 * hr \>100 * decongestant/antihistamine/pseudoephedrine/nasal steroid/oxymetazoline use within 12 hours. * prisoner * intubated * unable take po meds

Keywords: pseudoephedrine hyperbaric oxygen therapy prophylaxis