Breath-Hold Diving Injuries - A Primer for Medical Providers

ABSTRACT

Breath-hold divers, also known as freedivers, are at risk of specific injuries that are unique from those of surface swimmers and compressed air divers. Using peer-reviewed scientific research and expert opinion, we created a guide for medical providers managing breath-hold diving injuries in the field. Hypoxia induced by prolonged apnea and increased oxygen uptake can result in an impaired mental state that can manifest as involuntary movements or full loss of consciousness. Negative pressure barotrauma secondary to airspace collapse can lead to edema and/or hemorrhage. Positive pressure barotrauma secondary to overexpansion of airspaces can result in gas embolism or air entry into tissues and organs. Inert gas loading into tissues from prolonged deep dives or repetitive shallow dives with short surface intervals can lead to decompression sickness. Inert gas narcosis at depth is commonly described as an altered state similar to that experienced by compressed air divers. Asymptomatic cardiac arrhythmias are common during apnea, normally reversing shortly after normal ventilation resumes. The methods of glossopharyngeal breathing (insufflation and exsufflation) can add to the risk of pulmonary overinflation barotrauma or loss of consciousness from decreased cardiac preload. This guide also includes information for medical providers who are tasked with providing medical support at an organized breath-hold diving event with a list of suggested equipment to facilitate diagnosis and treatment outside of the hospital setting.

Recommendations on scuba diving in Birt-Hogg-Dubé syndrome

INTRODUCTION

Although very uncommon, severe injury and death can occur during scuba diving. One of the main causes of scuba diving fatalities is pulmonary barotrauma due to significant changes in ambient pressure. Pathology of the lung parenchyma, such as cystic lesions, might increase the risk of pulmonary barotrauma.

AREAS COVERED

Birt-Hogg-Dubé syndrome (BHD), caused by pathogenic variants in the FLCN gene, is characterized by skin fibrofolliculomas, an increased risk of renal cell carcinoma, multiple lung cysts and spontaneous pneumothorax. Given the pulmonary involvement, in some countries patients with BHD are generally recommended to avoid scuba diving, although evidence-based guidelines are lacking. We aim to provide recommendations on scuba diving for patients with BHD, based on a survey of literature on pulmonary cysts and pulmonary barotrauma in scuba diving.

EXPERT OPINION

In our opinion, although the absolute risks are likely to be low, caution is warranted. Given the relative paucity of literature and the potential fatal outcome, patients with BHD with a strong desire for scuba diving should be informed of the potential risks in a personal assessment. If available a diving physician should be consulted, and a low radiation dose chest computed tomography (CT)-scan to assess pulmonary lesions could be considered.

Dysbarism: An Overview of an Unusual Medical Emergency

Dysbarism is a general term which includes the signs and symptoms that can manifest when the body is subject to an increase or a decrease in the atmospheric pressure which occurs either at a rate or duration exceeding the capacity of the body to adapt safely. In the following review, we take dysbarisms into account for our analysis. Starting from the underlying physical laws, we will deal with the pathologies that can develop in the most frequently affected areas of the body, as the atmospheric pressure varies when acclimatization fails. Manifestations of dysbarism range from itching and minor pain to neurological symptoms, cardiac collapse, and death. Overall, four clinical pictures can occur: decompression illness, barotrauma, inert gas narcosis, and oxygen toxicity. We will then review the clinical manifestations and illustrate some hints of therapy. We will first introduce the two forms of decompression sickness. In the next part, we will review the barotrauma, compression, and decompression. The last three parts will be dedicated to gas embolism, inert gas narcosis, and oxygen toxicity. Such an approach is critical for the effective treatment of patients in a hostile environment, or treatment in the emergency room after exposure to extreme physical or environmental factors.

Recurrent Middle Ear Barotrauma in Student Pilots

INTRODUCTION: The present study evaluated the efficacy of the nine-step inflation-deflation tympanometric test for predicting recurrence of middle ear barotrauma.METHODS: Student pilots who were diagnosed with middle ear barotrauma from October 2010 to April 2011 were enrolled. The grade of barotrauma was assigned using Teed's classification. All subjects underwent tympanometry and nine-step inflation-deflation testing at first visit and after improvement. Recurrence was monitored for 2 wk after they resumed flight. The relationships among the recurrence of middle ear barotrauma, the grade and duration of disease, and tympanometric and nine-step test results were evaluated.RESULTS: There were 35 cases enrolled. According to Teed's classification, 16 cases were Grade 0 (45.7%) and 11 cases were Grade I (31.4%). Grade III was shown in seven cases (20.0%) and one subject was Grade IV (2.9%). The mean duration of illness was 5.9 d. In the initial 9-step tests, 29 subjects (85.3%) failed to pass the entire test. On follow-up tests, eight cases (22.9%) failed. Seven pilots (20.0%) showed recurrent middle ear barotrauma after resumed flight. All of the cases with recurrence failed the follow-up nine-step tests. The nine-step test showed high sensitivity and specificity values for predicting recurrence. A clear correlation was observed between recurrence and nine-step test results.DISCUSSION: The nine-step inflation-deflation test provides useful information about Eustachian tube function. The nine-step test can be useful to reduce the risk of recurrence of middle ear barotrauma in pilots.Sohn JH. Recurrent middle ear barotrauma in student pilots. Aerosp Med Hum Perform. 2019; 90(8):681-687.

Dynamic Rabbit Model of Ear Barotrauma

BACKGROUND: Establishing animal models of ear barotrauma (EB) to provide evaluation criteria for Eustachian tube dysfunction.METHODS: Using expansive sponges, 70 rabbits' right pharyngeal openings of the auditory tubes were blocked to cause dysfunction in the right Eustachian tubes. The right tympanic cavities of 65 rabbits were the Model Group (Subgroups 1-13) and these rabbits' left tympanic cavities were the Nonblockage Group. Hypobaric chamber tests (HCTs) at various vertical speeds (100 m · s^-1, 75 m · s^-1, 50 m · s^-1, and 15 m · s^-1) and altitudes (13,123 ft and 6562 ft) were conducted. The remaining five rabbits' right tympanic cavities were the Control Group and no HCTs were conducted. After HCTs, observations were made on rabbits' behavioral changes, oto-endoscope and tympanometry results, and pathological changes of the tympanic mucosae.RESULTS: 1) Rabbits in Subgroups 1-12 demonstrated EB, while Subgroup 13 and the Control Group did not. 2) Histopathology showed EB caused by rapid ascent/descent at 100 m · s^-1 was more severe than that of 75 m · s^-1 and 50 m · s^-1 (P < 0.01), and that there were no significant differences in EB caused by rapid ascent/descent at 75 m · s^-1 and 50 m · s^-1 (P > 0.05). There were no significant differences in pathological injuries at the altitudes of 6562 ft and 13,123 ft (P > 0.05). 3) Based on tympanic membrane structures, tympanometry, and histopathological results, rabbits' EB can be classified into mild, moderate, and severe.DISCUSSION: EB's dynamic models could be established through HCTs on rabbits with Eustachian tube dysfunction.Wang B, Xu X, Lin J, Jin Z. Dynamic rabbit model of ear barotrauma. Aerosp Med Hum Perform. 2019; 90(8):696-702.

A Free Diver with Hemoptysis and Chest Pain

[Full article available at http://rimed.org/rimedicaljournal-2019-02.asp].

Recurrent facial nerve baroparesis in a military diver: a case report

Middle ear barotrauma is common in diving. However, facial nerve baroparesis is a relatively rare complication. A dehiscent facial nerve canal may be a predisposing factor to developing this complication. Although there is an increasing number of facial baroparesis cases in the literature, they are likely still under-reported. In order to avoid unnecessary recompression treatments or detrimental effects to a professional diver's career, it is important to consider this in the differential diagnosis while evaluating dive injuries. This case report describes recurrent facial baroparesis in a military diver, which manifested on contralateral sides of his face. His initial presentation was misdiagnosed as an arterial gas embolism, which led to recompression treatment and a cardiac procedure. Upon recurrence about one year later, a complete work-up was done, which included an ENT evaluation and a CT scan. Imaging demonstrated a predisposing anatomic variant bilaterally. His symptoms resolved quickly and spontaneously both times, and he has been able to return to diving.

Barotrauma and Arterial Gas Embolism: A Diving Emergencies Simulation Case for Emergency Medicine Residents

Introduction

Arterial gas embolism (AGE) is a rare but severe complication of scuba diving. While AGE is most commonly encountered in coastal areas with high volumes of recreational divers, at-risk populations exist throughout the United States, making basic knowledge of the disease important for all emergency medicine (EM) physicians.

Methods

We used a hypothetical simulation case to train EM residents on diagnosis and management of AGE. A 32-year-old male presented with shortness of breath and unilateral neurologic deficits immediately after scuba diving. Residents were challenged to emergently diagnose and treat tension pneumothorax followed by diagnosis and treatment of AGE. A resident, attending, and simulation technician ran the case for four separate simulation teams in the simulation center with the addition of chest tube supplies to the basic resuscitation bay setup. Teams were allowed to use the internet in real time as a reference tool.

Results

Most teams arrived at the correct diagnosis using real-time internet searches, but none found the Divers Alert Network Emergency Hotline. Learners were debriefed both immediately and in a formal lecture. A follow-up survey showed good retention of knowledge.

Discussion

This case fills a significant knowledge and training gap for many EM physicians. AGE is a rare but highly morbid complication of diving, and EM residents should have knowledge of the disease and available consultation resources. Most EM residents will not have the opportunity to treat a diver during training, and the simulation environment provides a means to teach and practice this skill set.

Intraoperative use of low volume ventilation to decrease postoperative mortality, mechanical ventilation, lengths of stay and lung injury in adults without acute lung injury

BACKGROUND

Since the 2000s, there has been a trend towards decreasing tidal volumes for positive pressure ventilation during surgery. This an update of a review first published in 2015, trying to determine if lower tidal volumes are beneficial or harmful for patients.

OBJECTIVES

To assess the benefit of intraoperative use of low tidal volume ventilation (less than 10 mL/kg of predicted body weight) compared with high tidal volumes (10 mL/kg or greater) to decrease postoperative complications in adults without acute lung injury.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2017, Issue 5), MEDLINE (OvidSP) (from 1946 to 19 May 2017), Embase (OvidSP) (from 1974 to 19 May 2017) and six trial registries. We screened the reference lists of all studies retained and of recent meta-analysis related to the topic during data extraction. We also screened conference proceedings of anaesthesiology societies, published in two major anaesthesiology journals. The search was rerun 3 January 2018.

SELECTION CRITERIA

We included all parallel randomized controlled trials (RCTs) that evaluated the effect of low tidal volumes (defined as less than 10 mL/kg) on any of our selected outcomes in adults undergoing any type of surgery. We did not retain studies with participants requiring one-lung ventilation.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the quality of the retained studies with the Cochrane 'Risk of bias' tool. We analysed data with both fixed-effect (I² statistic less than 25%) or random-effects (I² statistic greater than 25%) models based on the degree of heterogeneity. When there was an effect, we calculated a number needed to treat for an additional beneficial outcome (NNTB) using the odds ratio. When there was no effect, we calculated the optimum information size.

MAIN RESULTS

We included seven new RCTs (536 participants) in the update.In total, we included 19 studies in the review (776 participants in the low tidal volume group and 772 in the high volume group). There are four studies awaiting classification and three are ongoing. All included studies were at some risk of bias. Participants were scheduled for abdominal surgery, heart surgery, pulmonary thromboendarterectomy, spinal surgery and knee surgery. Low tidal volumes used in the studies varied from 6 mL/kg to 8.1 mL/kg while high tidal volumes varied from 10 mL/kg to 12 mL/kg.Based on 12 studies including 1207 participants, the effects of low volume ventilation on 0- to 30-day mortality were uncertain (risk ratio (RR) 0.80, 95% confidence interval (CI) 0.42 to 1.53; I² = 0%; low-quality evidence). Based on seven studies including 778 participants, lower tidal volumes probably reduced postoperative pneumonia (RR 0.45, 95% CI 0.25 to 0.82; I² = 0%; moderate-quality evidence; NNTB 24, 95% CI 16 to 160), and it probably reduced the need for non-invasive postoperative ventilatory support based on three studies including 506 participants (RR 0.31, 95% CI 0.15 to 0.64; moderate-quality evidence; NNTB 13, 95% CI 11 to 24). Based on 11 studies including 957 participants, low tidal volumes during surgery probably decreased the need for postoperative invasive ventilatory support (RR 0.33, 95% CI 0.14 to 0.77; I² = 0%; NNTB 39, 95% CI 30 to 166; moderate-quality evidence). Based on five studies including 898 participants, there may be little or no difference in the intensive care unit length of stay (standardized mean difference (SMD) -0.06, 95% CI -0.22 to 0.10; I² = 33%; low-quality evidence). Based on 14 studies including 1297 participants, low tidal volumes may have reduced hospital length of stay by about 0.8 days (SMD -0.15, 95% CI -0.29 to 0.00; I² = 27%; low-quality evidence). Based on five studies including 708 participants, the effects of low volume ventilation on barotrauma (pneumothorax) were uncertain (RR 1.77, 95% CI 0.52 to 5.99; I² = 0%; very low-quality evidence).

AUTHORS' CONCLUSIONS

We found moderate-quality evidence that low tidal volumes (defined as less than 10 mL/kg) decreases pneumonia and the need for postoperative ventilatory support (invasive and non-invasive). We found no difference in the risk of barotrauma (pneumothorax), but the number of participants included does not allow us to make definitive statement on this. The four studies in 'Studies awaiting classification' may alter the conclusions of the review once assessed.

Alternobaric vertigo and facial baroparesis caused by scuba diving and relieved by chewing pineapple: a case report

Equalization of middle ear pressure is an important consideration for scuba divers. When middle ear pressure is asymmetric, a diver may experience alternobaric vertigo. Moreover, individuals with an underlying temporal bone dehiscence are predisposed to facial baroparesis. An understanding on behalf of fellow divers and emergency responders to recognize and differentiate facial baroparesis from decompression illness is critical. Misdiagnosis may lead to inappropriate treatment or unwarranted stoppage of diving. There have been a few dozen reported cases of facial baroparesis in the literature, but few have included firsthand accounts. This report describes an incidence of unilateral facial baroparesis preceded by alternobaric vertigo, with commentary from divers who witnessed the individual experiencing the facial paresis. The facial weakness in this case resolved within 15 minutes after the diver chewed on fresh pineapple. This report suggests that alternobaric vertigo may be a harbinger of facial baroparesis. Upon resurfacing divers should consider prophylactic measures that help to dilate the Eustachian tube such as chewing, yawning and swallowing in order to minimize the risk of middle ear pressure-induced vertigo or facial paresis.

Rescue therapeutic strategy combining ultra-protective mechanical ventilation with extracorporeal CO2 removal membrane in near-fatal asthma with severe pulmonary barotraumas: A case report

RATIONALE

Mechanical ventilation of severe acute asthma is still considered a challenging issue, mainly because of the gas trapping phenomenon with the potential for life-threatening barotraumatic pulmonary complications.

PATIENT CONCERNS

Herein, we describe 2 consecutive cases of near-fatal asthma for whom the recommended protective mechanical ventilation approach using low tidal volume of 6 mL/kg and small levels of PEEP was rapidly compromised by giant pneumomediastinum with extensive subcutaneousemphysema.

DIAGNOSES

Near fatal asthma.

INTERVENTION

A rescue therapeutic strategy combining extracorporeal CO2 removal membrane with ultra-protective extremely low tidal volume (3 mL/kg) ventilation was applied.

OUTCOMES

Both patients survived hospital discharge.

LESSONS

These 2 cases indicate that ECCO2R associated with ultra-protective ventilation could be an alternative to surgery in case of life-threatening barotrauma occurring under mechanical ventilation.

Repetitive freshwater diving: risk factors and prevalence of barotrauma

OBJECTIVE

The aim was to investigate the influence of repetitive scuba diving in fresh water on the middle ear mucosa. The prevalence of middle ear barotrauma (MEB) and risk factors for MEB were evaluated.

STUDY DESIGN

Prospective cohort study, Level of evidence 1b.

METHODS

During three days, 23 divers made 144 repetitive dives in a freshwater lake. Participants underwent otoscopic examinations and were questioned about ENT-related complaints in the morning before the first dive, in between the dives and after the last dive. Otoscopic findings were documented and classified according to the TEED scale (0 = normal eardrum to 4 = perforation), for the right and the left ear separately.

RESULTS

In total, 416 examinations were performed. ENT-related complaints during diving, mostly failed pressure equalization (74%), were reported after 10% of all dives. Most common pathology was MEB (TEED 1-3, 26%). Valsalva maneuver was possible during all exams. Significant increase of MEB (TEED⟩0) occurred with an increasing cumulative number of dives per day (P ⟨ .0001). Diving depth significantly influenced the MEB distribution (P = .035). MEB with higher TEED levels (2 and 3) was present only in the less experienced and intermediate divers. With increasing TEED level, more participants reported ENT-related problems (P ⟨ .0001). However, 74.4% of divers with MEB were still asymptomatic.

CONCLUSION

During three days of diving, the MEB prevalence increased with a cumulative number of dives per day. The major risk factors were diving depth and diving experience. Higher TEED level correlated with an increasing number of subjective ENT-related disorders during diving.

Otologic Hazards Related to Scuba Diving

Context:

As of 2015, more than 23 million scuba diver certifications have been issued across the globe. Given the popularity of scuba diving, it is incumbent on every physician to know and understand the specific medical hazards and conditions associated with scuba diving.

Evidence Acquisition:

Sources were obtained from PubMed, MEDLINE, and EBSCO databases from 1956 onward and ranged from diverse fields including otologic reviews and wilderness medicine book chapters.

Study Design:

Clinical review.

Level of Evidence:

Level 5.

Results:

Otologic hazards can be categorized into barotrauma-related injuries or decompression sickness.

Conclusion:

When combined with a high index of suspicion, the physician can recognize these disorders and promptly initiate proper treatment of the potentially hazardous and irreversible conditions related to scuba diving.

You're the Flight Surgeon

Lenz CR, Shields JL, Morgan AO. You're the flight surgeon: an unusual case of ground-level F-15 decompression illness. Aerosp Med Hum Perform. 2016; 87(10):906-909.

Headache Associated with Airplane Travel

This study presents six cases of headache that appeared only during flights and was not associated with other headache forms. The cases had severe headache attacks during some flights, when the plane was landing and taking off, with a unilateral and generally orbital and/or supraorbital localization. The attacks lasted between 15 and 20 min on average and recovered spontaneously, without any accompanying sign. We think that barotrauma caused by pressure changes in the cabin during take-off and landing could affect ethmoidal nerves (branching from the ophthalmic branch of the trigeminal nerve) that carry the senses of the mucosa on the inner surface of the paranasal sinuses, and/or nociceptors in ethmoidal arteries, thereby activating the trigeminovascular system and leading to headache.

Traumatic lung injury attributed to tornadic activity-induced barometric pressure changes in two dogs

CASE DESCRIPTION A 7-year-old castrated male Italian Greyhound (dog 1) and an approximately 1-year-old female Labrador Retriever (dog 2) were evaluated because of respiratory distress 8 and 10 days, respectively, after a tornado. CLINICAL FINDINGS No obvious external injuries were identified auscultation revealed decreased bronchovesicular sounds in the affected hemithorax of both dogs. Clinicopathologic changes were mild, with evidence of inflammation in both dogs. Thoracic radiography of both dogs revealed pneumothorax and pleural effusion with effacement of the diaphragm; findings on CT included severe pulmonary atelectasis of affected lung lobes with normal bronchial tree configurtion and no evidence of diaphragmatic hernia. TREATMENT AND OUTCOME Exploratory thoracotomy of both dogs confirmed CT findings Pulmonary parenchymal damage consistent with a large rupture was found in both patients. A large hematoma was adhered to the ruptured lung lobe of dog 1. Grossly affected lung tissue was removed; histologic examination revealed atelectasis, pulmonary fib osis, thrombosis, and minimal (dog 1) to marked (dog 2) inflammation Microbial culture of lung tissue yielded no growth for dog 1 and Streptococcus spp and Escherichia coli susceptible to amoxicillin-clavulanic acid for dog 2. Dog 1 had a recurrence of pneumothorax treated by drainage with a thoracostomy tube 1 month after surgery. Eighteen months after surgery, both dogs were reportedly doing well. CLINICAL RELEVANCE Development of clinical signs after a tornado, together with clinical, diagnostic imaging, surgical, and histologic findings led to a presumptive diagnosis of pulmonary barotrauma for both dogs. Long-term outcome for these dogs, treated at a referral hospital, was good.

Quantitative analysis of inner-ear barotrauma using a Eustachian tube function analyzer

OBJECTIVES

We investigated the relationship between Eustachian tube function and incidence of inner-ear barotrauma (IEBt) in recreational divers.

METHODS

Sixteen patients who experienced a scuba diving injury affecting the inner ear and 20 healthy volunteers who had not experienced a diving injury participated. Healthy volunteers and divers with IEBt received impedance tests regularly to assess Eustachian tube function. Test results from these groups were compared.

RESULTS

There were no significant differences between test results of IEBt divers and healthy volunteers. However, seven IEBt divers were judged to have irregular compliance curves on impedance testing. Seven of the 16 IEBt divers experienced vertigo. In nearly all of the IEBt divers with vertigo, hearing loss type was manifested as high-tone deafness, and IEBt symptoms appeared during diving. These symptoms were more serious especially when the diving depth was deeper.

CONCLUSIONS

To prevent IEBt in scuba divers, we recommend a thorough Eustachian tube function evaluation. Any dysfunction should be treated before engaging in scuba diving. We need to assess more divers who have experienced IEBt and thoroughly examine how their injury happened.

Ear, nose and throat and non-acoustic barotrauma

The organs of the ear, nose and throat (ENT) contain air- or gas-filled cavities, which make them sensitive to pressure changes. There is a specific pathophysiology involved when these structures are exposed to non-acoustic press ure changes, which are usually not traumatic in normals. The concepts of pathophysiology, diagnosis and treatment of these traumas in an emergency setting are reviewed.

Intraoperative use of low volume ventilation to decrease postoperative mortality, mechanical ventilation, lengths of stay and lung injury in patients without acute lung injury

BACKGROUND

During the last decade, there has been a trend towards decreasing tidal volumes for positive pressure ventilation during surgery. It is not known whether this new trend is beneficial or harmful for patients.

OBJECTIVES

To assess the benefit of intraoperative use of low tidal volume ventilation (< 10 mL/kg of predicted body weight) to decrease postoperative complications.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2014, Issue 9), MEDLINE (OvidSP) (from 1946 to 5 September 2014) and EMBASE (OvidSP) (from 1974 to 5 September 2014).

SELECTION CRITERIA

We included all parallel randomized controlled trials (RCTs) that evaluated the effect of low tidal volumes (defined as < 10 mL/kg) on any of our selected outcomes in adult participants undergoing any type of surgery. We did not retain studies with participants requiring one-lung ventilation.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the quality of the retained studies with the Cochrane 'Risk of bias' tool. We analysed data with both fixed-effect (I(2) statistic < 25%) or random-effects (I(2) statistic > 25%) models based on the degree of heterogeneity. When there was an effect, we calculated a number needed to treat for an additional beneficial outcome (NNTB) using the odds ratio. When there was no effect, we calculated the optimal size information.

MAIN RESULTS

We included 12 studies in the review. In total these studies detailed 1012 participants (499 participants in the low tidal volume group and 513 in the high volume group). All studies included were at risk of bias as defined by the Cochrane tool. Based on nine studies including 899 participants, we found no difference in 0- to 30-day mortality between low and high tidal volume groups (risk ratio (RR) 0.79, 95% confidence interval (CI) 0.40 to 1.54; I(2) statistic 0%; low quality evidence). Based on four studies including 601 participants undergoing abdominal or spinal surgery, we found a lower incidence of postoperative pneumonia in the lower tidal volume group (RR 0.44, 95% CI 0.20 to 0.99; I(2) statistic 19%; moderate quality evidence; NNTB 19, 95% CI 14 to 169). Based on two studies including 428 participants, low tidal volumes decreased the need for non-invasive postoperative ventilatory support (RR 0.31, 95% CI 0.15 to 0.64; moderate quality evidence; NNTB 11, 95% CI 9 to 19). Based on eight studies including 814 participants, low tidal volumes during surgery decreased the need for postoperative invasive ventilatory support (RR 0.33, 95% CI 0.14 to 0.80; I(2) statistic 0%; NNTB 36, 95% CI 27 to 202; moderate quality evidence). Based on three studies including 650 participants, we found no difference in the intensive care unit length of stay (standardized mean difference (SMD) -0.01, 95% CI -0.22 to 0.20; I(2) statistic = 42%; moderate quality evidence). Based on eight studies including 846 participants, we did not find a difference in hospital length of stay (SMD -0.16, 95% CI -0.40 to 0.07; I(2) statistic 52%; moderate quality evidence). A meta-regression showed that the effect size increased proportionally to the peak pressure measured at the end of surgery in the high volume group. We did not find a difference in the risk of pneumothorax (RR 2.01, 95% CI 0.51 to 7.95; I(2) statistic 0%; low quality evidence).

AUTHORS' CONCLUSIONS

Low tidal volumes (defined as < 10 mL/kg) should be used preferentially during surgery. They decrease the need for postoperative ventilatory support (invasive and non-invasive). Further research is required to determine the maximum peak pressure of ventilation that should be allowed during surgery.

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.

The O'Neill grading system for evaluation of the tympanic membrane: A practical approach for clinical hyperbaric patients

Eustachian tube dysfunction (ETD) and middle ear barotrauma (MEB) are the two most common complications of clinical hyperbaric oxygen (HBO2) treatment. The current grading system, the Teed's Classification, was first described in 1944 with modifications to this system over the years, but none are specific for the evaluation and treatment of patients undergoing clinical HBO2 therapy. Currently, the standard of care is a baseline otoscopic examination performed prior to starting HBO2 therapy. Repeat otoscopy is required for patients having ETD, pain or other symptoms during the compression and/or decompression phase of the treatment. Results from these examinations are used to determine the proper course of treatment for the ETD or MEB. The Teed's classification was not intended to correlate with the consistency of diagnosis, the clinical approach to relieving symptoms or the treatment of the inflicted trauma. It is not a practical tool for the modern hyperbaric team. We describe a newer grading system, the O'Neill Grading System (OGS), which allows simple, practical and consistent classification of ETD and MEB by all members of the clinical hyperbaric medicine team. Based on the O'Neill Grade assigned, evidence supported suggestions for appropriate actions and medical interventions are offered.

Barotrauma: Tooth under Pressure

With the growing number of air passengers, flight attendants, leisure pilots, as well as military and airline pilots, dentists may encounter physiological and pathological phenomena precipitated by high altitude. With the introduction of the self-contained breathing apparatus (SCUBA), many of these manifestations caused by changes in atmospheric pressure were reported in association with diving as well. Limited literature exists on this subject. Hence, this article aims to review literature concerning the classification, etiology and manifestations of barodontalgia, as well as important clinical considerations for its management.

The assessment and management of inner ear barotrauma in divers and recommendations for returning to diving

Inner ear barotrauma (IEBt) constitutes a spectrum of pressure-related pathology in the inner ear, with antecedent middle ear barotrauma (MEBt) common. IEBt includes perilymph fistula, intralabyrinthine membrane tear, inner ear haemorrhage and other rarer pathologies. Following a literature search, the pathophysiology, diagnosis, and treatment of IEBt in divers and best-practice recommendations for returning to diving were reviewed. Sixty-nine papers/texts were identified and 54 accessed. Twenty-five case series (majority surgical) provided guidance on diagnostic pathways; nine solely reported divers. IEBt in divers may be difficult to distinguish from inner ear decompression sickness (IEDCS), and requires dive-risk stratification and careful interrogation regarding diving-related ear events, clinical assessment, pure tone audiometry, a fistula test and electronystagmography (ENG). Once diagnosed, conservative management is the recommended first line therapy for IEBt. Recompression does not appear to cause harm if the diagnosis (IEBt vs IEDCS) is doubtful (limited case data). Exploratory surgery is indicated for severe or persisting vestibular symptoms or hearing loss, deterioration of symptoms, or lack of improvement over 10 days indicating significant pathology. Steroids are used, but without high-level evidence. It may be possible for divers to return to subaquatic activity after stakeholder risk acceptance and informed consent, provided: (1) sensorineural hearing loss is stable and not severe; (2) there is no vestibular involvement (via ENG); (3) high-resolution computed tomography has excluded anatomical predilection to IEBt and (4) education on equalising techniques is provided. There is a need for a prospective data registry and controlled trials to better evaluate diagnostic and treatment algorithms.

Facial baroparesis: a critical differential diagnosis for scuba diving accidents--case report

Facial nerve baroparesis is a rare and potentially under-reported complication of scuba diving. A diver, after surfacing from a shallow dive, developed isolated left-sided facial palsy accompanied by pain and decreased hearing in the left ear. No other signs or symptoms attributable to a scuba diving accident were detected. Forty minutes later, he heard a "pop" in the affected ear, after which all symptoms quickly resolved. Repeat neurological and ear examinations were normal. He showed no residual or new symptoms 24 hours later. The differential diagnosis of facial neurological deficit after diving includes decompression sickness, cerebral air embolism due to pulmonary barotrauma, facial nerve barotrauma and common conditions such as stroke and Bell's palsy. It is important to recognize the condition since recompression treatment can further damage the facial nerve.

Clinical signs of barotrauma in golden perch, Macquaria ambigua (Richardson), and associated effects on post-release mortality and health

This study assessed the effects of different retrieval depths (2, 10 or 20 m), surface intervals (none or 15 min) and release methods (untreated, vented or recompressed) on the incidence of external and internal clinical signs of barotrauma (ECSB and ICSB) and post-release mortality in golden perch, Macquaria ambigua (Richardson). Fish were assessed for ECSB before and after surface intervals and either monitored for mortality over 3 days in two deep cages or killed for internal examination. When all fish were left untreated, short-term mortality increased with retrieval depth from 0% and 4.2% among 2 and 10-m fish, respectively, to 19.2% among 20-m fish; while surface interval only affected the incidence of two ECSB (excess buoyancy and a prolapsed cloaca). Mortality was also greater among 20-m fish that were subjected to a 15-min surface interval and left untreated (22.2%) or vented (22.2%) than those that were recompressed (5.6%). Of the ECSB, only exophthalmia was associated with increased mortality, with half of the affected fish dying. However, many fish retrieved from 10 and 20 m also sustained numerous ICSB, including compressed gonads or vital organs and ruptured or collapsed, haemorrhaging swimbladders that remained deflated for up to 3 days after release.

Barodontalgias, dental and orofacial barotraumas: a survey in Swiss divers and caisson workers

Changing ambient pressure can lead to medical conditions in body cavities filled with air. Intraoral pain elicited by changes in pressure is referred to as barodontalgia. Dental barotraumas are defined as pressure-induced damages of teeth and restorations. The pathophysiologic background so far is not completely clear. The present study deals with dental and orofacial symptoms which can occur as a result of pressure variations. With the aid of cantonal administrations, diving associations, and tunnel construction firms, 520 pressure-exposed individuals (499 scuba/ professional divers, 21 caisson workers operating at excess pressure) were questioned regarding dental problems. A personal interview was conducted with affected individuals. Problems in the dental area were experienced by 15% of all respondents. Toothaches were suffered by 10.2% of the participants. Tooth injuries occurred in 6.3% of all interviewees (26 fractured amalgam restorations, 4 crown fractures, 3 losses of tooth fragments). A proportion of 11.3% among the respondents complained about temporomandibular joint problems or mucosal irritations (for example aphthae) related to the mouthpieces. Barotraumas outside the dental area were incurred by 31.9% of the divers. Of these, 69.9% concerned the ears and 65.6% occurred during the descent. Based on the results obtained from the survey and taking into account the current literature, recommendations for the prevention of barotraumas in divers and caisson workers were prepared. Diagnostic exclusion of dental pathologies and avoidance of retentive reconstruction materials are important factors for the prevention of barodontalgias and dental barotraumas.

Initial review of the U.S. Navy's pressurized submarine escape training outcomes

The U.S. Navy reinstituted pressurized submarine escape training (PSET) for submarine sailors in 2009 after a nearly 30-year absence. This training addresses escape from a disabled submarine at depth with the use of the Beaufort, Ltd. Mk 10 Submarine Escape and Immersion Equipment (SEIE) suit. Training is classified as "high-risk" due to previous U.S. and foreign navy experience with training-associated morbidity and mortality, particularly from diving-related illness. To reduce risk, medical screening procedures are performed. During the first 39 months of training, 7,025 students screened for PSET with 32% completing all phases, including two pressurized ascents. The most common reason for screening disqualification was presence of upper respiratory congestion. During training, middle ear barotrauma was responsible for 53% of attrition, primarily during the test of pressure.

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.

MRI findings of otic and sinus barotrauma in patients with carbon monoxide poisoning during hyperbaric oxygen therapy

BACKGROUND AND PURPOSE

To study the MRI findings of otic and sinus barotrauma in patients with carbon monoxide(CO) poisoning during hyperbaric oxygen (HBO) therapy and examine the discrepancies of otic and sinus abnormalities on MRI between barotrauma and acute otitis media with effusion.

MATERIALS AND METHODS

Eighty patients with CO-poisoning diagnosed with otic and sinus barotrauma after HBO therapy were recruited. Brain MRI was performed to predict delayed encephalopathy. Over the same period, 88 patients with acute otitis media with effusion on MRI served as control. The abnormalities of the middle ear and paranasal sinuses on MRI were noted and were compared between groups. Nine patients with barotrauma were followed up by MRI.

RESULTS

In the barotrauma group, 92.5% of patients had bilateral middle ear abnormalities on MRI, and 60% of patients had both middle ear cavity and mastoid cavity abnormalities on MRI in both ears. Both rates were higher than those in the control group (p = 0.000). In the two groups, most abnormalities on MRI were observed in the mastoid cavity. The rate of sinus abnormalities of barotrauma was 66.3%, which was higher than the 50% in the control group (p = 0.033). In the nine patients with barotrauma followed up by MRI, the otic barotrauma and sinus abnormalities had worsened in 2 patients and 5 patients, respectively.

CONCLUSION

MRI is able to depict the abnormalities of otic and sinus barotrauma in patients with CO-poisoning during HBO therapy and to differentiate these from acute otitis media with effusion.

Unilateral optic neuropathy from possible sphenoidal sinus barotrauma after recreational scuba diving: a case report

A case report is presented of a 35-year-old woman who developed a progressive right optic neuropathy while surfacing from a series of four recreational dives on the Great Barrier Reef, Queensland, Australia. The patient reported severe sudden onset blurred vision in the right eye associated with a mild headache and epistaxis on surfacing from diving. The patient had her first medical review the day after returning from her trip. At this time visual acuity in the right eye was 20/80, with left eye 20/20. There was a relative afferent pupillary defect in the right eye. A high-resolution computed tomography scan showed fluid in the right sphenoid sinus. Computed perimetry revealed patchy visual field loss in the right eye. The provisional diagnosis of sphenoidal sinus barotrauma-induced optic neuropathy was made. Over 10 days of observation, the visual acuity returned to 20/20 in the right eye and visual field changes resolved. This case highlights a very unusual cause of visual loss associated with diving.

[A study of the Eustachian tube function in patients with a scuba diving accident]

The scuba diving population has increased very much recently, bringing with it a rise in barotrauma. Ninety-seven patients with scuba diving-related accidents (34 males and 63 females; mean +/- SD: 36.6 +/- 10.3 years) and 39 healthy volunteers (9 males and 30 females; mean +/- SD: 41.1 +/- 16.9 years) without a history of Eustachian tube dysfunction participated in this study. All patients underwent audiometric measurements, including hearing testing, tympanometry, and Eustachian tube function testing (sonotubometry and impedance test). The tympanometry results of the majority of the patients were normal (Jerger A type), however, 83 of 97 patients (85.6%) were diagnosed as having Eustachian tube dysfunction: all patients had tubal stenosis. Compared with healthy volunteers, the Eustachian tube function in scuba diving patients was significantly lower. According to whether the affected parts were one ear or both ears, we classified these patients into 2 types, that is, the unilateral group and the bilateral group. The symptoms in the unilateral group were more serious than those in the bilateral group. In the unilateral group, the Eustachian tube functions of the affected ear did not always show lower than those of the healthy ear, so we thought that excessive positive pressure at the mesotympanum caused by the Valsalva maneuver might have affected not only the affected ear but also the healthy ear and have resulted in healthy ears being severely impaired by excessive positive pressure. To prevent scuba divers from pressure injury, we think that divers should have their Eustachian tube dysfunction accurately evaluated and any problems should be treated well.

A review of 17 years of telephone calls to the Australian Diver Emergency Service (DES)

INTRODUCTION

The Diver Emergency Service (DES) in Australia provides specialised medical advice on diving incidents 24 hours a day to divers, dive operators, families and health professionals. It is operated from the Hyperbaric Medicine Unit of the Royal Adelaide Hospital where the physician-on-call also carries the DES phone (1800-088200 or +61-8-8212-9242).

METHODS

Data from calls to the service have been compiled into a computer database since 1991. Calls for the 17 years from 1991 through 2007 were analysed.

RESULTS

A total of 6,083 calls were logged, an average of 358 calls a year. Calls from Queensland and New South Wales each accounted for 25% of calls. Calls originating from outside Australia have been increasing and now make up 25% of calls. The diver themselves initiated the call 50% of the time and 66% of the calls were about male divers. The age range of divers was 12 to 95 years old. The mean age has increased from 30 to 36 years, with a greater proportion of calls from divers aged 50 years or older (from 2% to 14%). The largest group of calls (37%) related to whether symptoms might be the result of decompression illness (DCI). DCI was considered to be the probable diagnosis in 17% of calls, and possible in a further 12%. Other common findings were barotrauma (11%) and questions regarding fitness to dive (15%). Older divers were more likely to call in relation to a medical problem.

CONCLUSION

Interpretation of these data is qualitative but the prolonged collection period of 17 years allows some consideration of trends as to who calls the DES and why.

Middle ear barotrauma after hyperbaric oxygen therapy - the role of insuflation maneuvers

OBJECTIVE

To analyze the association of insuflation maneuvers status before hyperbaric oxygen therapy with middle ear barotrauma.

MATERIALS AND METHODS

Fouty-one patients (82 ears) admitted to the Department of Hyperbaric Medicine from May 2011 to July 2012. Assessments occurred: before and after the first session, after sessions with symptoms. During the evaluations were performed: otoscopy with Valsalva and Toynbee maneuvers, video otoscopy and specific questionnaire. Middle ear barotrauma was graduated by the modified Edmond's scale. Tubal insuflation was classified in Good, Median and Bad according to combined results of Valsalva and Toynbee maneuvers.

INCLUSION CRITERIA

patients evaluated by an otolaryngologist before and after the first session, with no history of ear disease, who agreed to participate in the research (convenience sample).

RESULTS

Of the 82 ears included in the study, 32 (39%) had barotrauma after the first session. The rate of middle ear barotrauma according to tubal insuflation was: 17.9% (Good insuflation) 44.4% (Median insuflation) and 55.6% (Bad insuflation) (P = 0.013).

CONCLUSION

Positive Valsalva and Toynbee maneuvers before the first session, alone or associated were protective factors for middle ear barotrauma by ear after the first session.

[Diagnosis, treatment and medical evaluation of sinusitis and nasal polyp in aircrew]

OBJECTIVE

To sum up the experiences of diagnosis, treatment and medical evaluation of sinusitis and nasal polyp in aircrew.

METHOD

Ninety three aircrew with sinusitis and nasal polyp were included in the study.

RESULT

There were 11 cases with acute sinusitis and 82 cases with chronic sinusitis and nasal polyp. Of the 82 cases, there were 46 cases in class I (including 39 cases with symptoms and signs on ground in Ia, 7 cases only with signs in Ib), 36 cases in class II (no symptoms on ground but with symptoms of secondary barotraumas in flight, including 14 cases with secondary barosinusitis in IIa, 13 cases with secondary barotrauma in IIb, 9 cases with secondary barosinusitis and barotrauma in IIc ). Of the 82 cases, there were 24 cases in 1 stage of type I, 38 cases in 2 stage of type I, 7 cases in 3 stage of type I, 2 cases in 1 stage of type II, 6 cases in 2 stage of type II, 3 cases in 3 stage of type II, 2 cases in type III. Eighty four cases continued their flying jobs and 9 cases were permanently grounded.

CONCLUSION

Flying safe can be endangered by sinusitis and nasal polyp alone or with its secondary barotraumas. Chronic sinusitis and nasal polyp complicated with barotraumas are important causation for medical grounding. The aircrew with sinusitis and nasal polyp will be allowed to continue their flying jobs only after getting well curative effect and normal gas pressures of ear and nasal sinus.

Exploiting otoacoustic emission testing to identify clinical and subclinical inner ear barotrauma in divers: potential risk factor for sensorineural hearing loss

INTRODUCTION

Divers may sustain subclinical inner ear barotrauma (IEBT) that is not identified on pure-tone audiometry (PTA) but is potentially an important contributor to chronic sensorineural hearing loss (SNHL). Otoacoustic emission (OAE) testing, which identifies transient emission shifts (TESs) stemming from noise-induced inner ear injury, may be a more sensitive measure than PTA. Recognizing the salubrious health implications in mitigating the incidence and severity of SNHL in divers with earlier detection, we performed a pilot study investigating the potential of OAEs to identify clinical and subclinical IEBT (defined as a TES without an accompanying transient threshold shift) in divers subject to a provocative repetitive diving protocol.

METHODS

Eight US Navy-trained male divers participated in a repetitive diving protocol encompassing up to a maximum of 10 weeks of diving. All subjects received an otoscopic examination, tympanometry, and OAE testing on both ears prior to and immediately after each dive. Audiometry was evaluated prior to and after each week of repetitive diving.

RESULTS

There were 212 data pairs for comparison in the OAE testing. The average group wideband transient-evoked OAE shift was -1.24 dB. Only 25 significant threshold shifts were identified in over 1000 comparisons via audiometry.

CONCLUSIONS

OAE testing identified significant TES in a provocative repetitive diving protocol, supporting the assertion that both clinical and subclinical IEBT may contribute to chronic SNHL in divers. Exploiting this technology as an integral component of diving medical surveillance may identify those at risk for subsequent IEBT and hearing loss, facilitating opportunities for interventions to mitigate its severity or circumvent its development.

Middle ear barotrauma with hyperbaric oxygen therapy: incidence and the predictive value of the nine-step inflation/deflation test and otoscopy

We conducted a prospective study to determine the incidence of middle ear barotrauma in patients who were undergoing hyperbaric oxygen therapy (HBOT). We also investigated the value of the nine-step inflation/deflation test and otoscopic findings before and immediately after the initial HBOT session in predicting barotrauma in an attempt to establish some criteria for prophylaxis. The study was conducted on 36 ears of 18 adults who had no history of eustachian tube dysfunction. Patients were being treated with HBOT for sudden hearing loss, wound-healing complications, or complications of diabetes. After 7 days of HBOT, barotrauma was seen in 12 of the 18 patients (66.7%) and in 18 of the 36 ears (50.0%). The nine-step inflation/deflation tests, which were performed before and immediately after the initial HBOT session, were not predictive of barotrauma (p = 0.095 before and p = 0.099 after). However, otoscopic findings obtained immediately after the first session of HBOT were predictive of barotrauma, with a sensitivity and specificity of 83 and 100%, respectively. We conclude that patients with even minor positive pathologic findings on otoscopy immediately following HBOT are at increased risk of middle ear barotrauma if HBOT is to be continued without prophylaxis.

Pediatric sudden sensorineural hearing loss after diving

OBJECTIVE

Sensorineural hearing loss after diving from a low height has been rarely reported especially in children.

METHODS

We present and discuss a new case of pediatric sudden sensorineural hearing loss after diving.

RESULTS AND CONCLUSION

Medical and surgical approaches (indications and timing of explorative tympanotomy) to this occurrence are still controversial.

Tracheal rupture resulting in life-threatening subcutaneous emphysema

We present a case of a patient with severe chronic obstructive pulmonary disease who developed dramatic mediastinal and subcutaneous emphysema, without pneumothorax, following a difficult intubation. Misdiagnosis of tracheal rupture as barotrauma from alveolar overdistention initially delayed intervention and caused persistence of subcutaneous emphysema. Despite efforts to minimize tidal volume and airway pressure, the large airway disruption and positive-pressure ventilation resulted in tension subcutaneous emphysema with near-fatal hemodynamic compromise, oliguria, and respiratory acidosis. Decompression with subcutaneous vents immediately reversed the life-threatening circulatory and respiratory compromise and stabilized the patient until surgical correction of the tracheal tear could be accomplished.

Scuba diving: What you and your patients need to know

Self-contained underwater breathing apparatus (SCUBA) diving continues to gain popularity. General practitioners need to know the health requirements and contraindications so they can counsel patients appropriately. SCUBA diving injuries may not be apparent immediately and require knowledge and understanding for accurate diagnosis and treatment.

Facial baroparesis secondary to middle-ear over-pressure: a rare complication of scuba diving

A facial nerve palsy, as a result of middle-ear high pressure, is a rare complication of sub-aqua diving. It may occur as a result of an acute pressure change in the middle ear during ascent in those patients who have experienced difficulty equalizing their middle-ear pressure during the prior descent. We present the case history of this occurring in a 21-year-old diver and discuss the pathophysiology, management and the previous literature. The correct diagnosis of this condition is important if unnecessary, and potentially hazardous, recompression treatment is to be avoided.

[Acoustic and vestibular analysers in patients with mine explosion trauma]

The aim of the study was examination of the acoustic and vestibular functions in patients with mine explosion trauma. Acoustic and vestibular functions were studied in 27 patients (16 females and 11 males aged 19-66 years, mean age 37.2 +/- 4.12) admitted to the ENT clinic of Moscow city hospital N 1. All the patients had suffered from explosion in closed space. General clinical and complex otoneurological examinations were made including gustatory and olfactory investigations, studies of the facial skin sensitivity, nasal mucosa, corneal reflex, soft palate motility, audiometry and vestibulometry. The findings of the tests suggested the following conclusions: mine explosion damages hearing by impairment of both sound conduction (85.7%) and sound perception (61.2%), the latter suffering primarily at the cochlear level; damage to the cranial nerves V and XIII occurs at the level of the brain stem; mixed affection of the vestibular analyzer is seen primarily at the level of stem nuclei.

Evaluation of predive parameters related to eustachian tube dysfunction for symptomatic middle ear barotrauma in divers

OBJECTIVE

Eustachian tube dysfunction plays an important role in the pathogenesis of middle ear barotrauma. This investigation evaluates the predictive value of several parameters related to tubal dysfunction, in relation to symptomatic middle ear barotrauma in divers.

STUDY DESIGN

Prospective and blinded.

PATIENTS

Thirty-one sport scuba divers with normal predive audiometry, tympanometry, and general and otorhinolaryngologic examination.

METHODS

After an occurrence of middle ear barotrauma, the individual diver predive data on smoking, mild septal deviation, otitis media history, rhinosinusitis history, Valsalva, Toynbee, and nine-step inflation/deflation tympanometric test, as well as degree of mastoid pneumatization were registered for calculation of predictive value in relation to the barotrauma. All symptomatic ears were examined within 24 hours of diving by the investigator, who was blinded to the predive findings. Barotraumas that occurred during an upper respiratory tract infection were excluded.

RESULTS

Divers completed a total of 774 dives (median, 25; range, 3-100). Symptomatic middle ear barotrauma occurred in 19 ears (31%) of 14 divers (45%) at one time or another. The rate of tubal dysfunction measured by the nine-step test and a mastoid pneumatization below average were significantly higher in divers (p <0.05) as well as in ears (p <0.005) with barotrauma. Positive and negative predictive values of both parameters for subsequent barotrauma were between 69% and 76%. Combining the results into a two-test battery in a strict approach (positive on both) increased the positive predictive value to 86%.

CONCLUSION

Eustachian tube dysfunction measured by the nine-step test and a small size of the mastoid cell system seem to be risk factors for symptomatic middle ear barotrauma in otherwise healthy sport scuba divers. Evaluation of these factors in the predive examination of diving candidates may be useful in the determination of fitness to dive.

[Injuries caused by pressure differences while diving]

Barotraumas are caused by pressure differences. As described by Boyle's Law, barotraumas develop during the descent phase of diving (and much more rarely during the ascent). The most frequently affected are the ears and paranasal sinuses, in addition to the facial skin and eyes. The most important preventive measure is performing pressure compensation in the affected body cavities. Barotrauma is treated symptomatically.