Arterial gas embolism in a Special Forces combat dive student during free-swimming ascent training: A case study

Free-swimming ascent is taught to military divers and submariners as a self-rescue technique in the event of an emergency or a planned covert surfacing technique. Although this technique is infrequently used, it is considered a high-risk training event due to the risk and subsequent high morbidity and mortality of pulmonary barotrauma from pulmonary over-inflation injury. This case study will illustrate an example of a pulmonary overinflation injury and arterial gas embolism in an Army Special Forces Combat Diver who had no violation of technique while conducting a 50 foot free-swimming ascent to training standards and under the supervision of experienced Dive Supervisors. Additionally, the issue of allowing such individuals to return to diving is discussed.

Pulmonary gas embolism after parotid resection

Pulmonary gas embolism can have very variable consequences and may become a real challenge for anesthesiologists. We hereby report a case of major pulmonary embolism which took place under unusual circumstances and was documented echocardiographically.

[Case of portal venous gas and pneumatosis cystoides intestinalis occurring during chemotherapy for a castration-resistant prostate cancer]

Portal venous gas is a rare complication. We present a case of hepatic portal venous gas (HPVG) and pneumatosis cystoides intestinalis (PCI) in a patient treated with docetaxel for prostate cancer. An 80-year-old man with castration-resistant prostate cancer received 5 cycles of docetaxel. Diarrhea and vomiting appeared on the 4th day of the 5th cycle. An abdominal computed tomography (CT) scan revealed HPVG and PCI. Since there were neither peritoneal irritation signs nor intestinal necrosis, we performed conservative management. The HPVG and PCI were no longer detected in the abdominal CT scan on the 18th day. Mucosal injury of the bowel wall by docetaxel might have caused HPVG and PCI. This case report is the first description of HPVG and PCI in a patient with castration-resistant prostate cancer in Japan.

A retrospective cohort study of lidocaine in divers with neurological decompression illness

Lidocaine is the most extensively studied substance for adjuvant therapy in neurological decompression illness (DCI), but results have been conflicting. In this retrospective cohort study, we compared 14 patients who received adjuvant intravenous lidocaine for neurological decompression sickness and cerebral arterial gas embolism between 2001 and 2011 against 21 patients who were treated between 1996 and 2001 and did not receive lidocaine. All patients were treated with hyperbaric oxygen (HBO2) therapy according to accepted guidelines. Groups were comparable for all investigated confounding factors, except that significantly more control patients had made an unsafe dive (62% vs. 14%, p = 0.007). Groups had comparable injury severity as measured by Dick and Massey score (lidocaine 2.7 +/- 1.7, control 2.0 +/- 1.6), an adapted version of the Dick and Massey score, and the Blatteau score. Number of HBO2 sessions given was comparable in both groups (lidocaine 2.7 +/- 2.3, control 2.0 +/- 1.0). There was neither a positive nor a negative effect of lidocaine on outcome (relative risk for objective neurological signs at follow-up in the lidocaine group was 1.8, 95% CI 0.2-16). This is the first retrospective cohort study of lidocaine in neurological DCI. Since our study is under-powered to draw definitive conclusions, a prospective multicenter study remains the only way to reliably determine the effect of lidocaine in neurological decompression illness.

Ultrasound detection of vascular decompression bubbles: the influence of new technology and considerations on bubble load

INTRODUCTION

Diving often causes the formation of 'silent' bubbles upon decompression. If the bubble load is high, then the risk of decompression sickness (DCS) and the number of bubbles that could cross to the arterial circulation via a pulmonary shunt or patent foramen ovale increase. Bubbles can be monitored aurally, with Doppler ultrasound, or visually, with two dimensional (2D) ultrasound imaging. Doppler grades and imaging grades can be compared with good agreement. Early 2D imaging units did not provide such comprehensive observations as Doppler, but advances in technology have allowed development of improved, portable, relatively inexpensive units. Most now employ harmonic technology; it was suggested that this could allow previously undetectable bubbles to be observed.

METHODS

This paper provides a review of current methods of bubble measurement and how new technology may be changing our perceptions of the potential relationship of these measurements to decompression illness. Secondly, 69 paired ultrasound images were made using conventional 2D ultrasound imaging and harmonic imaging. Images were graded on the Eftedal-Brubakk (EB) scale and the percentage agreement of the images calculated. The distribution of mismatched grades was analysed.

RESULTS

Fifty-four of the 69 paired images had matching grades. There was no significant difference in the distribution of high or low EB grades for the mismatched pairs.

CONCLUSIONS

Given the good level of agreement between pairs observed, it seems unlikely that harmonic technology is responsible for any perceived increase in observed bubble loads, but it is probable that our increasing use of 2D ultrasound to assess dive profiles is changing our perception of 'normal' venous and arterial bubble loads. Methods to accurately investigate the load and size of bubbles developed will be helpful in the future in determining DCS risk.

Hyperbaric oxygen treatment for air or gas embolism

Gas can enter arteries (arterial gas embolism) due to alveolar-capillary disruption (caused by pulmonary overpressurization, e.g., breath-hold ascent by divers) or veins (venous gas embolism, VGE) as a result of tissue bubble formation due to decompression (diving, altitude exposure) or during certain surgical procedures where capillary hydrostatic pressure at the incision site is sub-atmospheric. Both AGE and VGE can be caused by iatrogenic gas injection. AGE usually produces strokelike manifestations, such as impaired consciousness, confusion, seizures and focal neurological deficits. Small amounts of VGE are often tolerated due to filtration by pulmonary capillaries. However, VGE can cause pulmonary edema, cardiac "vapor lock" and AGE due to transpulmonary passage or right-to-left shunt through a patent foramen ovale. Intravascular gas can cause arterial obstruction or endothelial damage and secondary vasospasm and capillary leak. Vascular gas is frequently not visible with radiographic imaging, which should not be used to exclude the diagnosis of AGE. Isolated VGE usually requires no treatment; AGE treatment is similar to decompression sickness (DCS), with first aid oxygen then hyperbaric oxygen. Although cerebral AGE (CAGE) often causes intracranial hypertension, animal studies have failed to demonstrate a benefit of induced hypocapnia. An evidence-based review of adjunctive therapies is presented.

[Iatrogenic gas embolism]

Gas embolism is the entry of air or medical gases into the blood circulation following invasive procedures, surgery, trauma or diving. The mortality of symptomatic gas embolism is high. Time is of the essence when initiating treatment, and gas embolism is often easily prevented. In this article, aetiology, frequency, pathophysiology, symptoms, diagnosis, treatment, outcome and prevention of both venous and arterial iatrogenic gas embolism are reviewed.

[Sex-induced air embolism in women]

Death as a result of air embolism has been reported following sexual activity such as vaginal insufflation or coitus a tergo. It is a very uncommon cause of death, however, during pregnancy and puerperium the risk increases due to non-collapsible veins at the placental site. Air embolism should be suspected in all sudden female deaths related to sexual activity in order to initiate appropriate treatment to minimize maternal and fetal morbidity and mortality.

Massive pulmonary air embolism during the implantation of pacemaker, case reports and literature analysis

OBJECTIVES

Pacemaker implantation has developed into a mature technology, meanwhile, implantable cardioverter-defibrillators (ICD) and cardiac resynchronization therapy (CRT), as extended pace making technology, are both carried out in rising frequency. Massive pulmonary air embolism is a rare but fatal complication accompanying with such pace making process. The objective of this study was to investigate the epidemiology, pathophysiological mechanism, occurrence and treatment for this kind of complication.

PATIENTS AND METHODS

Two cases of complicated massive pulmonary gas embolism were presented: one in CRT and the other in pacemaker implantation, both of which were captured rapidly and treated successfully by inhalation of high flow oxygen, closure of gas inflow tract, position change, and vasoactive drugs. Moreover, published literatures about air embolism in the process of pacemaker implantation or CRT/ICD were summarized and analyzed.

RESULTS

Complicated massive pulmonary air embolisms could be successfully resolved with satisfied short-term prognosis. Literature analysis showed that massive pulmonary air embolism is very rare in the course of pacemaker implantation, and coughing or deep breathing, advanced age, preoperative sedation, sheath with large cavity, improperly operating the hemostasis valve and diminished compliance of pulmonary circulation might be risk factors for air embolism.

CONCLUSIONS

Massive pulmonary air embolism during pace making which is very rare in the course of pacemaker implantation is one kind of life-threatening complication. Rapid judgment and timely treatment can avoid a catastrophic event, which could prevent adverse impact on the short-term prognosis, while further observation is required to explore the long-term prognosis.

Differential diagnosis and clinical relevance of pneumobilia or portal vein gas on abdominal x-ray

The purpose of the article is to present the differential diagnostic criteria between pneumobilia (air in the biliary system) and portal vein gas on abdominal x-ray. Differential diagnosis is essential because of its influence on patient management. Two patients are presented, one with pneumobilia and the other with portal vein gas on abdominal x-ray, with review of the relevant literature. Pneumobilia is often iatrogenic and even in cases of cholecystitis it is never a sole indication for emergency surgery. Patients with pneumobilia on abdominal x-ray can always be investigated further. On the other hand, the presence of air in portal vein is in most cases a sign of acute mesenteric ischemia. In adults with abdominal pain indicating intestinal ischemia (pain that is 'out of proportion' to clinical abdominal examination findings), it is an indication for emergency exploratory laparotomy. It is vital to act early when intestinal ischemia is suspected.

A systematic review of factitious decompression sickness

We present a case of factitious decompression sickness (DCS) involving a patient emergently treated at a hyperbaric medicine facility in New Zealand. Patients with factitious disorder feign illnesses such as DCS in order to receive care and attention despite the lack of an underlying illness. Other studies have suggested that 0.6% to as many as 9.3% of hospital admissions are factitious in nature. Therefore we believe that factitious DCS is occurring more often than hyperbaric clinicians suspect. DCS can be life-threatening, and hyperbaric medicine clinicians will almost always "err on the side of caution" when patients are referred with symptoms of DCS. Because DCS can be diagnosed based on subjective symptoms and self-reported history, there are opportunities for factitious patients to receive hyperbaric therapy. The costs associated with factitious DCS include transport, staff resources and preventing patients with treatable conditions from accessing the hyperbaric chamber. We performed a systematic review of the literature and found eight additional reported cases of confirmed or suspected factitious DCS. We report our findings and recommendations for hyperbaric medicine specialists regarding the recognition and management of factitious DCS.

End-organ protection in cardiac surgery

Mortality and morbidity postcardiac surgery with cardiopulmonary bypass (CPB) remain relative stable over the last decades, while the number of patients with increased comorbidity and more complex cardiac disease increases. Nevertheless, end-organ dysfunction and/or failure remain an issue. Multiple perioperative variables, such as non-optimal oxygen delivery, manipulation of the aorta, hyperlactatemia, type of anesthesia, surgical procedure and myocardial protection can be hold responsible for end-organ failure postcardiac surgery. However, it becomes more and more evident that also pre-existing factors, such as metabolic syndrome, renal insufficiency, hypertension, stroke and infection exacerbate mortality and morbidity. Unfortunately, these predisposing risk factors cannot be influenced perioperatively. Therefore, therapy should focus on controlling perioperative variables that, in combination with the predisposing factors, will further exacerbate organ dysfunction. In order to achieve this, more emphasis should be given to a patient-specific, goal-directed perfusion approach. This review will mainly focus on the impact of perioperative variables.

An unusual cerebral air embolism developing within the posterior circulation territory after a needle lung biopsy

We herein report the case of a 75-year-old woman with a paradoxical cerebral air embolism (CAE). She developed a bilateral visual disturbance at the time of needle puncture during a computed tomography (CT)-guided percutaneous needle lung biopsy in the face down position. The air density within the descending aorta on chest CT suggested the presence of a cerebral air embolism. Brain MRI demonstrated increased signal intensity in the bilateral occipital lobes on diffusion-weighted images. Usually, CAE occurs predominantly in the right hemisphere for anatomical reasons. The face down position and the anatomical features of the right subclavian artery, which diverges backward from the brachiocephalic artery, might explain such a unique distribution of CAE in this patient.

[Retrograde cavernous sinus air embolism after central venous catheter removal]

Air embolism is a rare, but occasionally fatal complication of peripheral and central venous catheterization. We present a case of an 89-year-old female, who had a central venous catheter placed in her right jugular vein during the perioperative period for right femoral subtrochanteric fracture. On the day following her operation, level of consciousness worsened a few minutes after the catheter was removed. CT scan showed air bubbles in bilateral cavernous sinuses and brachiocephalic vein. Administration of 100% oxygen was started, and she regained consciousness a few hours later, finally air bubbles disappeared on a CT scan performed 10 hours after onset. Air embolism should be taken into consideration when treating venous catheters, and appropriate O₂ administration and radiological examinations must be performed immediately if level of consciousness or vital signs deteriorate.

[Hyperbaric oxygen therapy for air embolism complicating computed tomography (CT)-guided needle marking of the lung]

Preoperative computed tomography( CT)-guided marking with a short hook wire for small sized lung tumors has become popular along with the spread of thoracoscopic surgery. Systemic arterial air embolism is a very rare but potentially fatal complication. The patient was a 79-year-old man who was found to have a mixed ground glass opacity shadow on chest CT. Almost immediately after marking, he lost consciousness and complete atrio-ventricular (AV) block was found on the electrocardiogram (ECG) monitor. Brain CT showed intravascular air bubbles in the right frontal lobe. Two hours later, his conscious level was recovered completely but remained left hemiplegia. Five hours later, he was transported to another hospital for hyperbaric oxygen therapy. After 3 episodes of the treatment, left hemiplegia recovered with slight sense disorder in the left little finger. When neurologic findings are remained after air embolism, hyperbaric oxygen therapy should be arranged immediately.

Coronary air embolism

The case report of acute coronary episode caused by air embolism associated with the removal of central vascular access, published in "Anaesthesiology Intensive Therapy"1/2012 aroused much interest [1]. Iatrogenic gas emboli are rare, albeit dramatic complications of therapeutic interventions,which result in persistent neurological symptoms in over 40% of cases [2].

Cerebral venous air embolism treated with hyperbaric oxygen: a case report

We present a case of cerebral venous gas embolism. Our patient made a complete neurological recovery after hyperbaric oxygen therapy (HBOT). The principles of HBOT, compressing and eliminating air bubbles and decreasing Β-2 integrin function, thus improving microcirculation, can only be beneficial in a situation where neurological damage is likely. Retrograde cerebral venous gas embolism is a less well recognised variant of gas embolism than the arterial variant. Its existence as a different entity is better recognised in the forensic medicine and radiology literature than in other disciplines. There is evidence in the literature of patients dying from this complication and others seemingly experiencing very little effect. This case report highlights this condition, to encourage others to look out for it and report outcomes, and to serve as a reminder that peripheral lines may be a potential cause of gas embolism, although the portal of air entry in our case remains uncertain.

Massive air embolism from continuous venovenous haemofiltration causing electromechanical dissociation in a cardiac surgical patient

Venous air embolism is a rare but life-threatening complication of continuous venovenous haemofiltration. We report a case of massive venous air embolism associated with haemofiltration in a 75-year-old man after complicated cardiac surgery. Haemofiltration circuitry and air detector alarms are not infallible and air embolism should be considered in patients receiving such therapy who develop cardiopulmonary instability. We discuss our early intervention, which focused on restoration of the circulation, prevention of further air entry, retrieval of air and supportive care. The use of transoesophageal echocardiography for diagnosis of air embolism and to aid the insertion of a pulmonary artery catheter for air aspiration was essential for management.

Complete neurological recovery after systemic air embolism during endoscopic retrograde cholangiopancreatography

Systemic air embolisms are a rare but often a fatal complication of endoscopic retrograde cholangiopancreatography (ERCP). Only few cases have been reported in scientific studies. This paper concerns a case of a systemic air embolism that occurred during endoscopic sphincterotomy for gallstone removal in a 79-year-old-woman and discusses possible mechanisms. The basic vital and neurologic signs of the woman deteriorated abruptly towards the end of the procedure. It was believed to be an air embolism and an urgent transthoracic echocardiography was ordered which confirmed the etiological diagnosis. Supportive measures were initiated: she was administered 100% oxygen, she was placed head down, left lateral position and fluid resuscitation was started to increase venous pressure. We considered hyperbaric oxygen therapy for neurological injury but, despite the severe initial presentation, she had a complete clinical recovery with only conservative treatment. Present experience stresses the importance of the awareness of this uncommon complication: a close vigilance of the anesthetists during ERCP is critical to ensure early diagnosis and a timely intervention.