Updates in Decompression Illness

Injuries and medical emergencies among international travellers

BACKGROUND

Tropical infectious diseases and vaccine-preventable emergencies are the mainstay of pre-travel consultations. However, non-communicable diseases, injuries and accidents that occur during travel are not emphasized enough in these settings.

METHODS

We performed a narrative review based on a literature search of PubMed, Google Scholar, UpToDate, DynaMed and LiSSa and on reference textbooks and medical journals dedicated to travel, emergency and wilderness medicine. Relevant secondary references were extracted. We also aimed to discuss newer or neglected issues, such as medical tourism, Coronavirus Disease 2019, exacerbations of co-morbidities associated with international travel, insurance coverage, health care seeking abroad, medical evacuation or repatriation and tips for different types of travellers' emergency medical kits (personal, group, physician handled).

RESULTS

All sources reviewed led to the selection of >170 references. Among epidemiological data on morbidity and deaths while abroad, only retrospective data are available. Deaths are estimated to occur in 1 in 100 000 travellers, with 40% caused by trauma and 60% by diseases, and <3% linked to infectious diseases. Trauma and other injuries acquired during travel, such as traffic accidents and drowning, can be reduced by up to 85% with simple preventive recommendations such as avoiding simultaneous alcohol intake. In-flight emergencies occur on 1 in 604 flights on average. Thrombosis risk is two to three times greater for travellers than for non-travellers. Fever during or after travel can occur in 2-4% of travellers, but in up to 25-30% in tertiary centres. Traveller's diarrhoea, although rarely severe, is the most common disease associated with travel. Autochthonous emergencies (acute appendicitis, ectopic pregnancy, dental abscess) can also occur.

CONCLUSIONS

Pre-travel medicine encounters must include the topic of injuries and medical emergencies, such as the risk-taking behaviours and foster better planning in a comprehensive approach along with vaccines and infectious diseases advices.

Quantification of shunt fraction using contrast ultrasound and indicator dilution in an in vitro model

Transthoracic saline contrast echocardiography is commonly used to assess intrathoracic shunt flow in vivo. Though the technique has many advantages (safe, simple, repeatable), the measurement technique lacks specificity, and the contrast agent has limited stability. This study sought to determine if the indicator dilution modeling technique could be applied to ultrasound contrast data to quantify shunt fraction and to determine if buoyant force has a significant effect on microbubble pathway determination at a "vascular" bifurcation. A model of the pulmonary circuit was perfused with blood at three distinct flow rates (low, medium and high) over shunt fractions ranging from ∼2-10 %. The buoyancy effect on contrast was quantified using a simplified in vitro model of a vascular bifurcation that had an upper and lower outflow tract where saline contrast formed from carbon monoxide (CO) gas passed through the bifurcation, was collected and quantified. The indicator dilution model was found to have a mean bias of - 3.2 % for the low flow stage, - 2.6 % for the medium flow stage and - 1.4 % for the high flow stage compared to volumetric measurements, suggesting agreement increases with increasing flow rate. Investigations of the buoyant effects revealed that at lower flow rates, contrast bubbles that encounter a bifurcation will favor the upper outflow tract over the lower. However, this effect is reduced by increasing the flow rate two-fold. These data identify that application of indicator dilution theory to contrast ultrasound data and the pathway ultrasound contrast travels in a network of tubules is flow dependent.

The management of patent foramen ovale in divers: where do we stand?

Diving is a fascinating activity, but it does not come without any cost; decompression illness (DCI) is one of the most frequent diseases occurring in divers. Rapid surfacing after diving causes alveolar rupture and bubbles release, which enter in the systemic circulation and could embolize numerous organs and tissues. The presence of patent foramen ovale (PFO) contributes to the passage of venous gas bubbles into the arterial circulation, increasing the risk of complications related to DCI. The diagnosis is established with a detailed medical history, a comprehensive clinical evaluation, and a multimodal imaging approach. Although the percutaneous closure of PFO is ambiguous for divers, as a primary prevention strategy, transcatheter management is considered as beneficial for DCI recurrence prevention. The aim of this study is to introduce the basic principles of DCI, to review the pathophysiological connection between DCI and PFO, to highlight the risk factors and the optimal treatment, and, last but not least, to shed light on the role of closure as primary and secondary prevention.

Decompression sickness in SCUBA divers

ABSTRACT

There are approximately 2.8 million active self-contained underwater breathing apparatus (SCUBA) divers in the US who are at risk for decompression sickness. This article discusses the pathophysiology, common signs and symptoms, and treatments of this multisystem complication of SCUBA diving.

Decompression sickness in SCUBA divers

ABSTRACT

There are approximately 2.8 million active self-contained underwater breathing apparatus (SCUBA) divers in the US who are at risk for decompression sickness. This article discusses the pathophysiology, common signs and symptoms, and treatments of this multisystem complication of SCUBA diving.

Wilderness Medicine: Impacts from the Weather, Water, and World

Pediatricians play an important role in the prevention of injuries and provide families with anticipatory guidance regularly. As more families are traveling and spending time outdoors, we must be adept at providing them with knowledge and resources to set them up for success on their adventures. Prevention and preparation frequently can help limit injuries sustained in the wilderness. This article will focus specifically on injuries related to the environment (eg, cold weather injuries, heat-related illnesses) and travel location (eg, high-altitude illness, marine-related injuries, diving medicine). [Pediatr Ann. 2022;51(6):e212-217.].

Post-mortem computer tomography in ten cases of death while diving: a retrospective evaluation

INTRODUCTION

Self-contained underwater breathing apparatus (SCUBA) diving deaths have always been a challenge for forensic pathologists. Post-mortem computer tomography (PMCT) allows intracorporeal gas visualization, contributing to identify the cases in which the cause of death is arterial gas embolism (AGE). However, in the literature, it is indicated to perform the radiological examination within 24 h after death.

MATERIALS AND METHODS

In this retrospective study, 32 cases of death who had undergone PMCT 24-48 h after death/corpse finding between January 2011 and March 2021 were analyzed, including ten cases of SCUBA divers who died of AGE. All cases' radiological images were reviewed to localize the intracorporeal gas distribution alongside other findings that are usually related to SCUBA diving death. A semi-quantitative evaluation was also performed.

RESULTS

Most of the divers showed gas within the left heart and the arteries. In addition, the semi-quantitative evaluation revealed that the divers presented a higher mean amount of intraarterial gas compared to the fresh corpses. On the other hand, the putrefied corpses presented gas within the portal system and generalized subcutaneous emphysema with higher frequency and quantity than the divers and fresh corpses.

CONCLUSION

Our cases suggested that the PMCT, even when performed 24-48 h after death, remains a valuable tool to diagnose AGE in cases of SCUBA diving deaths. In addition, with the limit of the small sample size, our data showed that at least a medium quantity of intraarterial gas, when not associated with a high amount of gas within the portal system and subcutaneous emphysema, could be considered a diagnostic criterion of AGE.

A General Overview on the Hyperbaric Oxygen Therapy: Applications, Mechanisms and Translational Opportunities

Hyperbaric oxygen therapy (HBOT) consists of using of pure oxygen at increased pressure (in general, 2-3 atmospheres) leading to augmented oxygen levels in the blood (Hyperoxemia) and tissue (Hyperoxia). The increased pressure and oxygen bioavailability might be related to a plethora of applications, particularly in hypoxic regions, also exerting antimicrobial, immunomodulatory and angiogenic properties, among others. In this review, we will discuss in detail the physiological relevance of oxygen and the therapeutical basis of HBOT, collecting current indications and underlying mechanisms. Furthermore, potential areas of research will also be examined, including inflammatory and systemic maladies, COVID-19 and cancer. Finally, the adverse effects and contraindications associated with this therapy and future directions of research will be considered. Overall, we encourage further research in this field to extend the possible uses of this procedure. The inclusion of HBOT in future clinical research could be an additional support in the clinical management of multiple pathologies.

Effect of Long-Term Diving Exposure on Sleep of Male Occupational Divers in Southern Taiwan: A Cross-Sectional Study

OBJECTIVE

Divers with a history of decompression sickness may be at high risk for sleep problems. However, limited studies have investigated the relationship between diving exposure and sleep problems of occupational divers. This study investigated the association between diving exposure and sleep quality and quantity among male occupational divers in southern Taiwan.

METHODS

This descriptive, cross-sectional study included 52 occupational divers and 121 non-divers recruited from southern Taiwan in 2018. Survey data were collected using the Taiwanese version of the Hospital Anxiety and Depression Scale, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and a self-report questionnaire that included demographic variables, diving exposure/protocols, and factors associated with sleep quality.

RESULTS

Among all participants examined, occupational divers were significantly more likely to have both poor sleep quality (adjusted odds ratio [OR] = 3.00; 95% confidence interval [CI] = 1.48-6.06; P = 0.002) and excessive daytime sleepiness (adjusted OR = 4.49; 95% CI = 2.12-9.52; P < 0.001). The diving exposure time, depth, ascent rate, and decompression table use showed no significant associations between poor and good sleepers in the divers group. However, a history of decompression sickness was associated with poor sleep quality among divers (adjusted OR = 2.20; 95% CI = 1.07-4.54; P = 0.032).

CONCLUSIONS

Our results showed that occupational divers had poor sleep quality and more excessive sleepiness than non-divers. Decompression sickness likely contributes to poor sleep quality. Prevention and early detection of decompression sickness-related sleep problems should be an occupational health priority.

Herpes Simplex Virus-2 Meningitis Masquerading as Pseudotumor Cerebri

We report a case of a 27-year-old obese female presenting with headache, blurry and double vision. She was found to have bilateral papilledema by an ophthalmologist and sent to the emergency department (ED). Cerebrospinal fluid (CSF) analysis showed elevated opening pressure and lymphocytic pleocytosis. Symptoms improved significantly after lumbar puncture (LP). Subsequently, polymerase chain reaction (PCR) for herpes simplex virus-2 (HSV-2) came back positive. This case represents an unusual presentation of HSV-2 meningitis, where the clinical picture was suggestive of pseudotumor cerebri or idiopathic intracranial hypertension (IIH), but CSF analysis revealed HSV-2. Papilledema and elevated intracranial pressure has not previously been described in association with HSV-2. Therefore, patients presenting with typical signs and meeting all diagnostic criteria for IIH in the presence of CSF pleocytosis may represent a distinct group of viral-induced intracranial hypertension. In these cases, an investigation of viral etiologies should be conducted.

Occupational Safety and Health in a Community of Shellfish Divers: A Community-Based Participatory Approach

In artisanal fishing communities in Chile, the access to occupational safety and health (OSH) is limited by factors such as the informality of employment. Our objective was to analyze the working and health conditions of workers in a coastal town in Southern Chile, under a community-based participatory approach. We carried out two independent social dialogue workshops within the community. The first one (N of participants = 25) was aimed to identify the strengths, weaknesses and challenges for preventing decompression sickness among divers. The second workshop (N of participants = 10) was set to identify the work processes and to map the occupational risks during seafood harvesting and processing in the community. Community members' training for handling and preventing decompression sickness among divers, and the collaboration between a local health representative, stakeholders and authorities, were identified as contributing factors in reducing fatalities and sequels among divers in the past. Technology and safety on board the vessels, training of healthcare personnel in OSH, and access to health programs, were identified as remaining challenges. Through risk mapping, the participants identified the relationship between working and health conditions in the community, reinforcing the necessity of improving access to health and social security. The community participation in identifying and analyzing working and health conditions could be the first step for a strategy to address OSH through primary health care in rural communities. Community empowerment and involvement in action plans, training on basic OSH for health care workers, and public policies are required.

Vascular Myelopathies

PURPOSE OF REVIEW

Neurologists should be able to identify clinical and neuroimaging features that distinguish vascular disorders from other causes of myelopathy.

RECENT FINDINGS

Although certain clinical features suggest a vascular etiology in acute and chronic myelopathy settings, accurate MRI interpretation within the clinical context is key. Recent studies have shown vascular myelopathies are frequently misdiagnosed as transverse myelitis, and recognition of this diagnostic pitfall is important. Many different vascular mechanisms can cause myelopathy; this article provides a comprehensive review that simplifies disease categories into arterial ischemia, venous congestion/ischemia, hematomyelia, and extraparenchymal hemorrhage.

SUMMARY

It is important to recognize and manage vascular disorders of the spinal cord as significant causes of acute, subacute, and progressive myelopathy.

Ultrasound in the diagnosis of acute-phase decompression sickness

A 53-year-old man, who performed a 44-minute dive to a depth of 21 meters, felt severe abdominal pain with dyspnea after surfacing. An ultrasound study showed a marked snowstorm pattern in the portal vein of the liver and right ventricle, and whole body computed tomography revealed multiple gas bubbles in the right ventricle, inferior vena cava, portal, mesenteric and femoral vein. He was thus diagnosed to have decompression sickness and was therefore transported to another hospital to undergo hyperbaric oxygen therapy. Patients who present with abdominal symptoms after diving should be immediately evaluated by ultrasound and computed tomography.

<i>Cutis marmorata<i> as a manifestation of decompression illness

We present imagines of skin lesions due to a decompression illness (known as cutis marmorata). These alterations are usually transient, but they could be a warning sign of a more severe manifestation of decompression illness.

Bubbles in the skin microcirculation underlying cutis marmorata in decompression sickness: Preliminary observations

INTRODUCTION

The cutaneous form of decompression sickness (DCS) known as cutis marmorata is a frequent clinical presentation. Beyond a general acceptance that bubbles formed from dissolved inert gas are the primary vector of injury, there has been debate about pathophysiology. Hypotheses include: 1) local formation of bubbles in the skin or its blood vessels; 2) arterialisation of venous bubbles across a right to left shunt (RLS) with local amplification in bubble size after reaching supersaturated skin via the arterial circulation; and 3) passage of arterialised venous bubbles to the cerebral circulation with stimulation of a sympathetically mediated vasomotor response.

METHODS

Four divers exhibiting cutis marmorata had the underlying tissue examined with ultrasound 4-5.5 hours after appearance of the rash. All subsequently underwent transthoracic echocardiography with bubble contrast to check for a RLS.

RESULTS

In all cases numerous small bubbles were seen moving within the skin microvasculature. No bubbles were seen in adjacent areas of normal skin. All four divers had a large RLS.

CONCLUSION

This is the first report of bubbles in skin affected by cutis marmorata after diving. The finding is most compatible with pathophysiological hypotheses one and two above. The use of ultrasound will facilitate further study of this form of DCS.

Case report: Physiological changes due to a rapid ascent from 55 metres underwater

We present the case of a diver who experienced an uncontrolled ascent from 55 m and presented with a severe decompression illness. She was clinically shocked and in multi organ failure due to massive fluid shifts. She demonstrated bilateral lower limb loss of power and sensation and required multiple hyperbaric therapy sessions. With joint critical care, hyperbaric and physical therapy involvement, she was discharged some five weeks after her presentation with an independent level of function.

Decompression sickness: a guide for emergency nurses

Decompression sickness (DCS) is commonly associated with diving or occupational exposure to compressed air, and is a life-threatening condition if left untreated. This article provides an overview of the pathophysiology and types of DCS. It also explains the principles of care for people presenting to the emergency department with DCS that emergency nurses must be familiar with, including the recognition of its signs and symptoms and the initial management required. It is important that emergency nurses are aware of the optimal treatment protocol for DCS, which involves its early recognition, prompt administration of high-flow oxygen and referral to the nearest hyperbaric chamber for recompression.

Vibration and bubbles: a systematic review of the effects of helicopter retrieval on injured divers

INTRODUCTION

Vibration from a helicopter during aeromedical retrieval of divers may increase venous gas emboli (VGE) production, evolution or distribution, potentially worsening the patient's condition.

AIM

To review the literature surrounding the helicopter transport of injured divers and establish if vibration contributes to increased VGE.

METHOD

A systematic literature search of key databases was conducted to identify articles investigating vibration and bubbles during helicopter retrieval of divers. Level of evidence was graded using the Oxford Centre for Evidence-Based Medicine guidelines. A modified quality assessment tool for studies with diverse designs (QATSDD) was used to assess the overall quality of evidence.

RESULTS

Seven studies were included in the review. An in vitro research paper provided some evidence of bubble formation with gas supersaturation and vibration. Only one prospective intervention study was identified which examined the effect of vibration on VGE formation. Bubble duration was used to quantify VGE load with no difference found between the vibration and non-vibration time periods. This study was published in 1980 and technological advances since that time suggest cautious interpretation of the results. The remaining studies were retrospective chart reviews of helicopter retrieval of divers. Mode of transport, altitude exposure, oxygen and intravenous fluids use were examined.

CONCLUSION

There is some physical evidence that vibration leads to bubble formation although there is a paucity of research on the specific effects of helicopter vibration and VGE in divers. Technological advances have led to improved assessment of VGE in divers and will aid in further research.

Spinal Decompression Sickness in an Experienced Scuba Diver: A Case Report and Review of Literature

Decompression sickness from diving is a rare but potentially reversible cause of spinal injury. Early treatment with hyperbaric oxygen is associated with a better neurologic outcome, making prompt recognition and management clinically important. We describe a case of a 65-year-old diver who presented with thoracic back pain and bilateral leg weakness after a 70 feet of sea water (fsw) (21 meters of sea water [msw]) dive, with no acute abnormality on spinal magnetic resonance imaging (MRI). He made a partial recovery after extended hyperbaric oxygen therapy. We discuss the epidemiology and pathophysiology of central nervous system injury in decompression sickness, as well as acute management and prognostic factors for recovery, including the role of adjunctive therapies and the implications of negative MRI. Ultimately, clinicians should make the diagnosis of spinal cord decompression sickness based primarily on clinical evaluation, not on MRI findings.

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.

Comments on unresponsive decompression illness case

We have read the case report about a decompression sickness that was unresponsive to hyperbaric oxygen treatment in your journal. Presented case is intriguing; however, we think there are some contradictive issues in the discussion of the case. In this letter, we aim to comment on these issues that may raise further question. Bubble formation plays a very important role for decompression sickness, but proposed mechanism is incorrect as nitrogen does not change state during decompression. Use of terminology for diving-related diseases and comments on properties of helium may cause misunderstandings. Also importance of history of the dive in evaluating an accident should be emphasized.

Hypoxia and hyperbaric oxygen therapy: a review

Hypoxia causes a cascade of activity from the level of the individual down to the regulation and function of the cell nucleus. Prolonged periods of low oxygen tension are a core feature of several disease states. Advances in the study of molecular biology have begun to bridge the gap between the cellular response to hypoxia and physiology. Hyperbaric oxygen therapy is a treatment for hypoxic- and inflammatory-driven conditions, in which patients are treated with 100% oxygen at pressures greater than atmospheric pressure. This review discusses hypoxia, the physiologic changes associated with hypoxia, the responses that occur in the cells during hypoxic conditions, and the role that hyperbaric oxygen therapy can play as part of the treatment for many patients suffering from diseases with underlying hypoxia.

Implementation of Targeted Temperature Management in a Patient with Cerebral Arterial Gas Embolism

Cerebral arterial gas embolism (CAGE) shows various manifestations according to the quantity of gas and the brain areas affected. The symptoms range from minor motor weakness, headache, and confusion to disorientation, convulsions, hemiparesis, unconsciousness, and coma. A 46-year-old man was transferred to our emergency department due to altered sensorium. Immediately after a controlled ascent from 33 m of seawater, he complained of shortness of breath and rigid extremities, lapsing into unconsciousness. He was intubated at another medical center, where a brain computerized axial tomography scan showed no definitive abnormal findings. Pneumothorax and obstructing lesions were apparent in the left thorax of the computed tomography scan. Following closed thoracostomy, we provided hyperbaric oxygen therapy (HBOT) using U.S. Navy Treatment Table (USN TT) 6A. A brain magnetic resonance imaging diffusion image taken after HBOT showed acute infarction in both middle and posterior cerebral arteries. We implemented targeted temperature management (TTM) to prevent worsening of cerebral function in the intensive care unit. After completing TTM, we repeated HBOT using USN TT5 and started rehabilitation therapy. He fully recovered from the neurological deficits. This is the first case of CAGE treated with TTM and consecutive HBOTs suggesting that TTM might facilitate salvage of the penumbra in severe CAGE.

Acute kidney injury caused by decompression illness successfully treated with hyperbaric oxygen therapy and temporary dialysis

A 52-year-old Japanese male professional diver was referred to our hospital for decompression illness (DCI). After 1 h of diving operation at 20 m below sea level, he complained of dyspnea, chest pain, and abdominal pain. He dove again, intending to ease the symptoms, but the symptoms were never relieved. He dove for a total of 4 h. No neurological abnormalities were observed. Computed tomography images revealed portal venous gas and mesenteric venous gas, in addition to bubbles in the femoral veins, pelvis, lumbar canal, intracranial sinuses, and joints. Hyperbaric oxygen therapy (HBOT) was immediately administered. His symptoms improved after the first course of HBOT, however, the patient had anuria for almost 36 h after admission and exhibited acute kidney injury (AKI). Serum creatinine and creatine kinase (CK) levels were increased to maximal values of 6.16 mg/dL and 18,963 U/L, respectively. Blood flow signals were not detected on kidney Doppler ultrasound. We considered that AKI was caused by blood flow impairment and capillary leak syndrome due to DCI in addition to rhabdomyolysis secondary to arterial gas embolism in the skeletal muscles. Temporary dialysis was required to correct the acidemia and electrolyte disturbance. Diuretic phase was initiated, and the patient was put off dialysis on day 3. Serum creatinine and CK levels returned to normal on day 11. He was successfully treated without any complications. Although AKI is a rare manifestation, we should consider AKI risk in patients with severe DCI.

Spinal Cord Infarcts: Risk Factors, Management, and Prognosis

OPINION STATEMENT

There are no standard guidelines for treatment of spinal cord ischemia due to how rare it is and the diverse etiology and presentations involved. In addition, to date, there have been no large clinical trials examining ideal pharmacologic treatment options for spinal cord infarct. In our practice, we rely on hemodynamic augmentation initiated as soon as possible. Otherwise, treatment is usually geared towards the etiology of spinal cord ischemia. For instance, spinal cord ischemia occurring after aortic aneurysmal repair may improve with CSF drainage through a lumbar catheter in the periprocedural setting. Vertebral artery dissection should be treated with antithrombotics. If no clear etiology is found and there is evidence of atherosclerosis in other vascular beds, then management is focused on risk factor modification with blood pressure and glucose control, statins, and antithrombotics.