Acclimatization to diving: a systematic review.

Multiday hyperbaric exposure has been shown to reduce the incidence of decompression sickness (DCS) of compressed-air workers. This effect, termed acclimatization, has been addressed in a number of studies, but no comprehensive review has been published. This systematic review reports the findings of a literature search. PubMed, Ovid Embase, The Cochrane Library and Rubicon Research Repository were searched for studies reporting DCS incidence, venous gas embolism (VGE) or subjective health reports after multiday hyperbaric exposure in man and experimental animals. Twenty-nine studies fulfilled inclusion criteria. Three epidemiological studies reported statistically significant acclimatization to DCS in compressed-air workers after multiday hyperbaric exposure. One experimental study observed less itching after standardized simulated dives. Two human experimental studies reported lower DCS incidence after multiday immersed diving. Acclimatization to DCS has been observed in six animal species. Multiday diving had less consistent effect on VGE after hyperbaric exposure in man. Four studies observed acclimatization while no statistically significant acclimatization was reported in the remaining eight studies. A questionnaire study did not report any change in self-perceived health after multiday diving. This systematic review has not identified any study suggesting a sensitizing effect of multiday diving, and there is a lack of data supporting benefit of a day off diving after a certain number of consecutive diving days. The results suggest that multiday hyperbaric exposure probably will have an acclimatizing effect and protects from DCS. The mechanisms causing acclimatization, extent of protection and optimal procedure for acclimatization has been insufficiently investigated.

Iatrogenic Arterial Gas Embolism From Esophagogastroduodenoscopy.

BACKGROUND: Arterial gas embolus (AGE) is a rare complication of esophagoduodenoscopy (EGD) that has been described in only a few case reports in the literature. The exact etiology remains unknown, but many of the cases share some common characteristics. CASE REPORT: We report the case of a 52-year-old otherwise healthy man who underwent outpatient EGD for a sensation of retained food in his esophagus. During the procedure, he suffered a tonic-clonic seizure, bradycardia, and hypoxia. Subsequent emergency department workup showed pneumocephalus on computed tomography brain imaging, and he was diagnosed with a cerebral AGE (CAGE). He was transferred to our facility for treatment of CAGE with hyperbaric oxygen therapy (HBOT). After multiple hyperbaric treatments, he was discharged with a residual left hemiparesis, which represented a significant improvement in his overall neurologic status. We also present a review of similar EGD CAGE cases from the literature and discuss their outcomes and the need for HBOT. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although CAGE from EGD is rare, these patients will often be transferred to the ED from gastrointestinal procedural suites and an emergency physician should understand that an iatrogenic CAGE can result from this procedure and that CAGE is a clinical diagnosis. Definitive care at a critical care-capable hyperbaric chamber will provide the patient with the best chance of meaningful recovery, and transport should be arranged as expeditiously as possible.

Cerebral Air Embolism after Esophagogastroduodenoscopy: Insight on Pathophysiology, Epidemiology, Prevention and Treatment.

BACKGROUND: Air embolism is an extremely rare complication that can follow gastrointestinal endoscopy. The most accepted treatment of cerebral air embolism (CAE) is hyperbaric oxygen (HBO). Limited evidence suggests that lidocaine may have a neuroprotective effect. The exact mechanism does not appear to be well elucidated. METHODS: We conducted a literature search using multiple combinations of keywords from PubMed and Ovid Medline databases according to the PRISMA guidelines. We included articles with cases of air embolism caused by an esophagogastroduodenoscopy (EGD). We excluded cases related to other procedures e.g. colonoscopy, endoscopic retrograde cholangiopancreatography, cholangioscopy, Kasai procedure, bronchoscopy, laparoscopy or thoracoscopy. We were able to identify 30 cases of CAE associated with EGD. We included our experience in treating one patient with CAE after elective EGD. RESULTS: Given the results of our literature search and this patient's characteristics, we chose to treat our patient with HBO and lidocaine infusion. Our case series consists of 31 patients of post EGD CAE, the mean age was 63.7 ± 11.14 years, 38.7% of the patients were women (n = 12). 38.7% of the cases underwent esophageal dilatation (n = 12), while 19.35% had EGD biopsy (n = 6), 9.6% had variceal ligation (n = 3), and 3.22% had variceal banding (n = 1). In 20 out of 31 cases, echocardiography has been documented, 20% of those patients (n = 4) had patent foramen ovale. HBO was used in treatment of 48% of cases (n = 15), among the included patients, 61% survived (n = 19). Our patient showed significant neurological improvement. CONCLUSIONS: Despite the rare incidence of CAE during or after EGD, physicians should be aware of this potential complication. In patients who develop sudden acute neurological symptoms, early diagnosis and intervention may prevent devastating neurological injury and death. The most accepted emergent treatment for CAE includes HBO, consideration of lidocaine, and work-up of source of the air embolism.

Health care worker decompression sickness: incidence, risk and mitigation.

Inadvertent exposure to radiation, chemical agents and biological factors are well recognized hazards associated with the health care delivery system. Less well appreciated yet no less harmful is risk of decompression sickness in those who accompany patients as inside attendants (IAs) during provision of hyperbaric oxygen therapy. Unlike the above hazards where avoidance is practiced, IA exposure to decompression sickness risk is unavoidable. While overall incidence is low, when calculated as number of cases over number of exposures or potential for a case during any given exposure, employee cumulative risk, defined here as number of cases over number of IAs, or risk that an IA may suffer a case, is not. Commonly, this unique occupational environmental injury responds favorably to therapeutic recompression and a period of recuperation. There are, however, permanent and career-ending consequences, and at least two nurses have succumbed to their decompression insults. The intent of this paper is to heighten awareness of hyperbaric attendant decompression sickness. It will serve as a review of reported cases and reconcile incidence against largely ignored individual worker risk. Mitigation strategies are summarized and an approach to more precisely identify risk factors that might prompt development of consensus screening standards is proposed.

Arterial gas embolism: a review of cases at Prince of Wales Hospital, Sydney, 1996 to 2006.

Arterial gas embolism may occur as a complication of diving or certain medical procedures. Although relatively rare, the consequences may be disastrous. Recent articles in the critical care literature suggest the non-hyperbaric medical community may not be aware of the role for hyperbaric oxygen therapy in non-diving related gas embolism. This review is part of an Australian appraisal of experience in the management of arterial gas embolism over the last 10 years. We identified all patients referred to Prince of Wales Hospital Department of Diving and Hyperbaric Medicine with a diagnosis of arterial gas embolism from 1996 to 2006. Twenty-six patient records met our selection criteria, eight iatrogenic and 18 diving related. All patients were treated initially with a 280 kPa compression schedule. At discharge six patients were left with residual symptoms. Four were left with minor symptoms that did not significantly impact quality of life. Two remained severely affected with major neurological injury. Both had non-diving-related arterial gas embolism. There was a good outcome in the majority of patients who presented with arterial gas embolism and were treated with compression.

Symptomatic cerebral air embolism during neuro-angiographic procedures: incidence and problem avoidance.

BACKGROUND: While clinically symptomatic cerebral air embolism secondary to neuro-angiographic procedures is rare, the incidence in a large series of procedures is unknown. Understanding this complication's frequency and etiology is critical if systems are to be instituted to reduce its incidence. METHODS: We prospectively reviewed 4,568 consecutive neuro-angiographic procedures performed between June 2000 and July 2005. The occurrence and etiology of a symptomatic air embolus was noted, and an incidence was calculated for all procedures and for diagnostic arteriograms and interventional procedures individually. RESULTS: Four symptomatic cerebral arterial air emboli occurred in 4,568 neuro-angiographic procedures over the five-year period (0.08%). No events occurred in 3,150 diagnostic angiograms while four occurred during 1,418 interventional procedures (0.2%). Two cases occurred during aneurysm coiling embolization (2/548; 0.4%); one case occurred during a carotid stent placement (1/138; 0.7%); one occurred during an internal carotid artery balloon occlusion test (1/73; 1.3%). Three of these complications resulted in permanent neurologic deficits while one resulted in a transient neurologic change that cleared within 60 min of onset. Sources for the emboli included the pressurized arterial flush lines connected to internal carotid artery catheters (three cases) and sudden hypotension with air subsequently entering the internal carotid artery catheter (one case). Two patients were treated with hyperbaric oxygen therapy. CONCLUSION: Symptomatic cerebral air embolism is a rare event during neuro-angiographic procedures. Analysis of the etiologies of this infrequent event may permit us to further reduce its incidence.

[Air embolism and exploratory hysteroscopy: myths or realities? Preliminary results]. / Embolie gazeuse et hystéroscopie exploratoire: mythes ou réalités? Note préliminaire.

OBJECTIVE: Authors tried to evaluate the prevalence of air embolism which is a severe complication of carbon dioxide hysteroscopy. DESIGN: On one hand, a retrospective inquiry with 18 hyperbaric oxygen therapy units over a 8 year period (1985 to 1992 included); and on the other hand, a prospective study with monthly survey to 84 public Gynaecology units during a 2 year period (January 1991 the 1st to December 1992 the 31st). RESULTS: From the 18 hyperbaric oxygen therapy units receiving iatrogenic air embolism, gynaecologic endoscopy represent 20% of the patients. Among these, 2/3 come from laparoscopy and 1/3 from hysteroscopy. In the prospective study, 42 public Gynaecology units made 5,140 carbon dioxide hysteroscopies. Three air embolism were declared in this population (i.e. 0.58/1000) with 1 death and 2 recoveries without sequelae after hyperbaric oxygen therapy. CONCLUSION: Analysis of these cases suggest that, for this risk, one should oppose ambulatory hysteroscopy without anaesthesia to hysteroscopy under general anaesthesia with frequent cervical dilatation, prolonged duration and different underlying pathology.

Dysbaric cerebral air embolism in Hawaii.

Cerebral air embolism is a major cause of death and disability among sport scuba divers. To better define the epidemiologic and clinical manifestations of this infrequently encountered disorder, the records of all recompression treatments in Hawaii from 1976 through 1979 were reviewed. Forty-two cases of dysbaric air embolism (DAE) were identified on the basis of clinical criteria, accounting for 18% of the patients undergoing recompression treatment for diving-related disorders during this four-year period. In 22 patients (52%), DAE was part of a dysbarism syndrome that involved one or more forms of decompression sickness and/or in which DAE could not be differentiated from neurologic decompression sickness. The presenting signs and symptoms varied, with asymmetric multiplegia being the most common finding. Two patients died, giving a case fatality rate of 5% for those who survived until reaching the recompression chamber. Overall, 78% of the cases manifested either complete (61%) or substantial (17%) recovery with recompression and adjunctive medical measures. Traditional concepts of dysbaric cerebral air embolism are not adequate to explain the spectrum of clinical manifestations encountered in this condition.

Delayed cerebral edema complicating cerebral arterial gas embolism: case histories.

A disquieting and rarely described feature of the treatment of arterial gas embolism (AGE) is the high incidence of relapse following good to excellent initial responses to recompression therapy. This paper includes a discussion of the issues involved in the etiology and clinical approach to the specific problem of relapse and relates experience from selected clinical cases to a modified therapeutic approach that has been introduced into Royal Navy diving and submarine medicine practice. It illustrates how and why current treatment procedures have been expressly designed to minimize the incidence of relapse and to modify favorably the pathophysiological responses (particularly vasogenic cerebral edema) associated with cerebral AGE.