Grommets in HBOT patients: GA vs LA, unanswered questions.

We read with interest the article on grommet procedures for patients undergoing hyperbaric oxygen therapy (HBOT), and have a number of comments. It appears the authors may have missed a number of cases. In a previous paper from The Townsville Hospital Hyperbaric Unit (TTH HMU), Commons et al presented 14 of 106 patients (13%) who required grommets over the period between June 2009 and May 2010. These patients are included in the Lamprell et al data set. Figure 1 shows an apparent spike in their cases in 2010 (n = 13, part of the period covered in the previous paper) when compared to the remaining four years of their study (mean number of cases 4.5 per year, for an incidence of 3%). This difference in incidence is statistically significant (chi square = 8.336, df = 1, P = 0.004). We suspect the difference may be the result of missed cases rather than a true spike; however, it is not possible to determine this from the paper. Lamprell et al describe identifying cases using the TTH HMU patient database. Did the authors also consider using the operating theatre database and/or ENT clinic records to ensure all cases were captured? We also have concerns regarding Lamprell's primary outcome measure: time from ENT referral to date of re/commencement of HBOT. These data are presented as median values with the associated ranges, rather than an interquartile range (IQR), the traditional measure of dispersion in non-parametric data. We believe the data sets contain a number of outliers that should be excluded, e.g., 98 days. We ask to see the IQRs and box-and-whisker plots for both data sets, and suspect the statistically significant difference in medians might not remain with outliers excluded from the analysis. There is also no discussion about the clinical relevance of this difference of seven days. Based on the most common indications for HBOT listed, most patients would have received at least 30 daily sessions of HBOT. What impact does a delay of seven days have on their treatment? As doctors who have worked at this HMU, we know patients preferentially received their grommets under GA prior to 2012 at the request of the ENT surgeon, who believed that insertion under LA was poorly tolerated. The authors do not describe whether the insertion of grommets under LA was associated with patient discomfort; a limitation of this retrospective paper, but a clinically relevant factor in the decision-making process of which form of anaesthesia to use. The paper by Lamprell et al has shown us that patients may experience a more rapid insertion of grommets and return to HBOT, if inserted under LA versus GA, but this difference may not be important clinically. We believe the authors may have failed to collect all cases and exclude outliers and this, coupled with the lack of documentation about patient satisfaction with insertion under LA, leaves us with more questions than answers.

Middle ear barotrauma in a tourist-oriented, condensed open-water diver certification course: incidence and effect of language of instruction.

INTRODUCTION: In Professional Association of Diving Instructors (PADI) Open Water Diver certification courses that cater to tourists, instruction is often condensed and potentially delivered in a language that is not the candidate's native language. OBJECTIVE: To assess the incidence of middle ear barotrauma (MEBt) in open-water diver candidates during a condensed four-day certification course, and to determine if language of instruction affects the incidence of MEBt in these divers. METHOD: The ears of participating diving candidates were assessed prior to commencing any in-water compression. Tympanic membranes (TM) were assessed and graded for MEBt after the confined and open-water training sessions. Tympanometry was performed if the candidate had no movement of their TM during Valsalva. Photographs were taken with a digital otoscope. RESULTS: Sixty-seven candidates participated in the study. Forty-eight had MEBt at some time during their course. MEBt was not associated with instruction in non-native language (adjusted odds ratio = 0.82; 95% confidence intervals 0.21-3.91). There was also no significant association between the severity of MEBt and language of instruction. CONCLUSION: Open-water diver candidates have a high incidence of MEBt. Education in non-native language does not affect the overall incidence of MEBt.

A prospective analysis of independent patient risk factors for middle ear barotrauma in a multiplace hyperbaric chamber.

INTRODUCTION: Middle ear barotrauma (MEBT) is the most common complication of hyperbaric oxygen therapy (HBOT). We wished to determine whether independent risk factors could predict which patients will require tympanostomy tubes in order to continue HBOT. METHODS: Data regarding demographics, medical history and physical examination were collected prospectively over one year. Multivariate logistic regression was used to analyse the data. RESULTS: One hundred and six patients were included. The cumulative risk of MEBT over the first five treatments was 35.8% and that for needing tympanostomy tubes was 10.3%, while that for needing tubes at any time was 13.2%. Risk factors for MEBT on bivariate analysis were older age, history of ENT radiation and anticoagulant use. Risk factors for requiring tympanostomy tubes included a history of cardiovascular disease and patients being treated for an infective condition. The adjusted multivariate logistic model identified history of difficulty equalising as the only characteristic significantly associated with MEBT during the first five treatments, adjusted odds ratio (AOR) (95%CI): 11.0 (1.1 - 111.7). Being female, AOR (95%CI): 24.7 (1.8 - 339.7), and having a history of cardiovascular disease, AOR (95%CI): 20.7 (2.0 - 215.3), were significantly associated with the need for tympanostomy tubes during the first five HBOT, but there was no significant association between any other characteristics and the need for tubes at any point. CONCLUSION: Despite some significant risk factors for MEBT being identified, we were unable to predict accurately enough which patients needed tympanostomy tubes during their HBOT to recommend these being placed prophylactically in selected patients.

'Sea legs': sharpened Romberg test after three days on a live-aboard dive boat.

INTRODUCTION: The sharpened Romberg test (SRT) is commonly used by diving and hyperbaric physicians as an indicator of neurological decompression illness (DCI). People who spend a prolonged time on a boat at sea experience impairment in their balance on returning to shore, a condition known as mal de debarquement ('sea legs'). This conditioning of the vestibular system to the rocking motion of a boat at sea may impact on the utility of the SRT in assessing a diver with potential DCI after a live-aboard dive trip. AIM: To assess the impact 'sea legs' has on the SRT after three days on a live-aboard dive trip. METHODS: Thirty-nine staff and passengers of a three-day, live-aboard dive trip performed a SRT before and after their journey, with assessment of potential variables, including middle ear barotrauma, alcohol consumption, sea-sickness and occult DCI. RESULTS: There was no statistically significant impact on SRT performance, with 100% completion pre-trip and 35 out of 36 divers (97.2%) post-trip. There were trends towards more attempts being required and time needed for successful SRT post-trip, but these were not statistically significant. There was a small, but noteworthy incidence of middle-ear barotrauma, with seven people affected pre-trip, and 13 post-trip. There was a higher incidence in student divers. Middle-ear barotrauma did not appear to have a direct impact on SRT performance. CONCLUSION: There was no significant impact on SRT performance resulting from 'sea legs' after three days at sea. Recreational divers, especially dive students, have a substantial incidence of mild middle ear barotrauma.