Systemic gas embolism complicating pulmonary contusion. Diagnosis and management using transesophageal echocardiography

Systemic arterial gas embolism (SAGE) as a complication of bronchoscopic lung biopsy: a case report and systematic literature review

Background

Systemic arterial gas embolism (SAGE) is a rare yet serious and underrecognized complication of bronchoscopic procedures. A recent case of presumed SAGE after transbronchial needle aspiration prompted a systematic literature review of SAGE after biopsy procedures during flexible bronchoscopy.

Methods

We performed a systematic database search for case reports and case series pertaining to SAGE after bronchoscopic lung biopsy; reports or series involving only bronchoscopic laser therapy or argon plasma coagulation (APC) were excluded. Patient data were extracted directly from published reports.

Results

A total of 29 unique patient reports were assessed for patient demographics, specifics of the procedure, clinical manifestations, diagnostic findings, and clinical outcomes. Cases of SAGE occurred after multiple types of bronchoscopic biopsy and under both positive and negative pressure ventilation. The most common clinical findings were neurologic, followed by cardiac manifestations; temporal patterns included acute onset of cardiac or neurologic emergencies immediately after biopsy, or delayed awakening post-procedure. There was a high mortality rate among cases (28%), with residual neurologic deficits also common (24%).

Discussion

SAGE is an underrecognized but severe adverse effect of bronchoscopic lung biopsy, which often presents with acute coronary or cerebral ischemia or delayed awakening from sedation. It is important for all physicians who perform bronchoscopic biopsies to be aware of the clinical manifestations and therapeutic management of SAGE in order to mitigate morbidity and mortality among patients undergoing these procedures.

Bronchovenous Fistula During Adult Cardiac Surgery: A Case Report

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Bronchovenous fistula (BVF) associated with adult cardiac surgery is a rarely reported life-threatening condition. We present a 75-year-old woman who developed a BVF during cardiac surgery. Dense adhesion in the pleural and pericardial cavities was noted. Restrictive pulmonary pathology required high airway pressure. Transesophageal echocardiography and hemoglobin measurement were helpful for the timely diagnosis of BVF, which was controlled by transection of the right upper pulmonary vein where a vent catheter had been inserted. Injuries around the cannulated site presumably initiated the BVF, which was worsened by high-pressure ventilation. Therefore, cannulation site might be a risk factor for BVF.

Influx of air into the left atrium during lung resection

OBJECTIVES

In this study, we aimed to determine conditions associated with the development of air bubbles in the pulmonary veins during lung resection.

METHODS

A total of 28 patients who underwent lung resection at our institution between October 2016 and March 2018 were included in the study. An intraoperative transesophageal echocardiography was conducted, and the influx of air bubbles in the orifice of the pulmonary vein leading to the left atrium was observed during lung resection.

RESULTS

The median age of all patients was 75 years. The study included 13 men and 15 women. Moreover, seven, 14, and seven patients underwent wedge resection, segmentectomy, and lobectomy, respectively. The presence of air bubbles was observed in 15 patients and was detected when the lung parenchyma was cut (13 patients) or compressed (3 patients) using staplers and when an energy device was used (1 patient). No postoperative organ infarction occurred in any patients.

CONCLUSIONS

Although the presence of air bubbles was noted in the pulmonary vein during lung resection via transesophageal echocardiography, the clinical condition of the patients in our study did not deteriorate. The clinical significance of air bubbles is not clear. Therefore, more data about such events must be collected in future.

Massive systemic arterial air embolism caused by an air shunt after blunt chest trauma: A case report

INTRODUCTION

Systemic arterial air embolism (SAAE) is a rare but fatal condition, with only a few cases reported, and the detailed etiology underlying SAAE remains unknown. We report a first case of massive SAAE after blunt chest injury, wherein the presence of traumatic air shunt was confirmed by direct observation during surgery. We also summarize our experience with six other SAAE cases.

PRESENTATION OF CASE

A 68-year-old woman was admitted in a state of cardiac arrest after a fall. Emergency room thoracotomy determined complete transection of left main bronchus and left superior pulmonary vein. Postmortem computed tomography (CT) revealed full of air in the aortic arch, the descending aorta, and the great vessels. Therefore, one of the cause of death might be SAAE.

DISCUSSION

An air shunt after blunt chest trauma can cause SAAE, and clinical signs and operative findings can provide clues for possible SAAE. The bronchopulmonary vein fistula, the aortic injury and full-thickness myocardial injury have the potential to become traumatic air shunts. In cases with a coexisting air shunt, pneumothorax, lung contusions and positive-pressure ventilation can be risk factors for SAAE, as sources of air continually entering the systemic arterial circulation.

CONCLUSION

SAAE is caused by an air shunt following trauma. Clinical signs and operative findings summarized in this case should aid in the recognition of possible SAAE.

Atriobronchial Fistula Complicated by Septic Cerebral Air Emboli After Pulmonary Vein Ablation

OBJECTIVE

To describe a case of an infected atriobronchial fistula as a late complication after pulmonary vein ablation, leading to septic air emboli and requiring urgent cardiac surgery.

DATA SOURCES

Clinical observation.

STUDY SELECTION

Case report.

DATA EXTRACTION

Relevant clinical information. PubMed was searched for relevant literature.

DATA SYNTHESIS

Given its high success and low complication rate, pulmonary vein isolation is expected to be increasingly performed worldwide. Despite its success, some of its rare complications are potentially devastating and are difficult to diagnose early. In this report, we present the case of a 32-year-old woman, who was readmitted to hospital 2 months after pulmonary vein ablation. The clinical picture resembled meningococcemia with spreading petechiae on legs and arms raising concern for Waterhouse-Friderichsen syndrome. Further echocardiographic investigation led to the discovery of massive amounts of intracardiac air which demanded urgent lung isolation and sternotomy. Intraoperatively a small infected left atrial perforation was oversewn and a fistula to the right main bronchus was closed by means of an autologous pericardial patch. One month later, still revalidating, she could be discharged home with only minor neurologic sequelae.

CONCLUSIONS

Clinicians should be aware of the dramatic complications of invasive antiarrhythmic procedures and their atypical and late presentations. Better preprocedural appreciation of cardiac wall thickness, early echocardiographic diagnosis, and swift referral for cardiac surgery might impact outcome dramatically.

Role of Transesophageal Echocardiography in Blunt Chest Trauma

Patients who suffer blunt chest trauma are at risk for injury to the heart, and the thoracic aorta and its branch vessels. Unrecognized injury to the heart or aorta may lead to life threatening complications. Therefore, the physician caring for the trauma patient must be able to accurately and rapidly diagnose cardiac and thoracic aortic injury. Transesophageal echocardiography is an ideal tool to diagnose cardiac and aortic injury in the patient with blunt chest trauma because it provides high quality images of the heart and thoracic aorta and can safely and rapidly be performed in the emergency department, operating suite or intensive care unit. To utilize transesophageal echocardiography most effectively, the echocardiographer must be familiar with the indications, limitations, and piffalls of transesophageal echocardiography in patients with blunt chesttrauma. This review describes the role of transesophageal echocardiography in evaluating the patient with blunt chest trauma for cardiac, thoracic aortic, and mediastinal injury.

Massive cerebral air embolism after blunt chest trauma with full neurological recovery

Cerebral air embolism (CAE) is a common, often lethal, complication in blunt and penetrating chest trauma. The factors affecting the outcome of CAE patients are poorly understood, and there is no generally accepted treatment algorithm. In this report, we present the case of a 28-year-old male motorcyclist with a massive CAE, including bilateral internal carotid artery air on computed tomographic examination following blunt chest trauma. With prehospital intubation, oxygen, transfusion, and open laparotomy but without any specific treatment regarding the CAE, a follow-up computed tomography (CT) scan approximately 6 hours later showed resolution of the cerebrovascular air. Recovery was unremarkable, and the patient was discharged neurologically intact after 22 days.

Cerebral gas embolism in a case of Influenza A-associated acute respiratory distress syndrome treated with high-frequency oscillatory ventilation

A 22-year-old obese asthmatic woman with Influenza A (H1N1)-associated acute respiratory distress syndrome died from cerebral artery gas emboli with massive cerebral infarction while being treated with High-Frequency Oscillatory Ventilation in the absence of a right to left intracardiac shunt. We review and briefly discuss other causes of systemic gas emboli (SGE). We review proposed mechanisms of SGE, their relation to our case, and how improved understanding of the risk factors may help prevent SGE in positive pressure ventilated patients.

Transesophageal echocardiographic diagnosis of bronchopulmonary vein fistula complicating mitral valve replacement

A bronchopulmonary vein fistula (BVF) establishes a communication between a pulmonary vein and the alveolar space presumably secondary to alveolar rupture from increase in alveolar pressure. This rare fistula allows air to move continuously from the lungs to a pulmonary vein and into the left side of the heart causing systemic air embolization which is often fatal. We describe an adult patient undergoing a second mitral valve replacement surgery in whom intra-operative transesophageal echocardiography proved crucial in diagnosing BVF by showing persistent and increased streaming of air bubbles into the left heart from the left superior pulmonary vein during each positive pressure ventilation cycle with consequent inability to de-air the heart. This allowed initiation of appropriate management. The patient eventually had a fatal outcome from multiple organ infarcts.

High-frequency oscillatory ventilation with and without arteriovenous extracorporeal lung assist in patients with severe respiratory failure

PURPOSE

Elimination of carbon dioxide by an arteriovenous extracorporeal lung assist (av-ECLA) can facilitate the lung protective capabilities of high-frequency oscillatory ventilation (HFOV). This case series describes patients treated with HFOV because of severe respiratory failure with and without additional av-ECLA.

METHODS

A retrospective analysis of 31 patients regarding patient characteristics, gas exchange, respirator settings, hemodynamics, and outcome. In 18 patients, av-ECLA was started before, together with, or during HFOV.

RESULTS

The initial arterial carbon dioxide tension before HFOV and av-ECLA was higher in patients who received av-ECLA compared with patients without (P = .043): 65 (48-84) mm Hg and 50 (44-60) mmHg (median and interquartile range). The initial arterial oxygen tension (Pao(2))/inspiratory oxygen fraction (Fio(2)) index in patients who received av-ECLA was 79 (63-133) mm Hg. The Pao(2)/Fio(2) index immediately before HFOV was 84 (65-124) mm Hg (av-ECLA) and 121 (68-150) mmHg (no av-ECLA) and improved to 149 (89-231) mm Hg and 200 (117-233) mmHg during HFOV. Similarly, the oxygenation index improved. No statistically significant differences among groups were detected for Pao(2)/Fio(2) index, oxygenation index, and arterial carbon dioxide tension immediately before and during HFOV. The hospital mortality was 39% (av-ECLA) and 69% (no av-ECLA).

CONCLUSIONS

High-frequency oscillatory ventilation improved the oxygenation in patients with severe respiratory failure. Additional av-ECLA may facilitate using lung protective HFOV settings in more severe lung injury and hypercapnia.

Acute management of vascular air embolism

Vascular air embolism (VAE) is known since early nineteenth century. It is the entrainment of air or gas from operative field or other communications into the venous or arterial vasculature. Exact incidence of VAE is difficult to estimate. High risk surgeries for VAE are sitting position and posterior fossa neurosurgeries, cesarean section, laparoscopic, orthopedic, surgeries invasive procedures, pulmonary overpressure syndrome, and decompression syndrome. Risk factors for VAE are operative site 5 cm above the heart, creation of pressure gradient which will facilitate entry of air into the circulation, orogenital sex during pregnancy, rapid ascent in scuba (self contained underwater breathing apparatus) divers and barotrauma or chest trauma. Large bolus of air can lead to right ventricular air lock and immediate fatality. In up to 35% patient, the foramen ovale is patent which can cause paradoxical arterial air embolism. VAE affects cardiovascular, pulmonary and central nervous system. High index of clinical suspicion is must to diagnose VAE. The transesophgeal echocardiography is the most sensitive device which will detect smallest amount of air in the circulation. Treatment of VAE is to prevent further entrainment of air, reduce the volume of air entrained and haemodynamic support. Mortality of VAE ranges from 48 to 80%. VAE can be prevented significantly by proper positioning during surgery, optimal hydration, avoiding use of nitrous oxide, meticulous care during insertion, removal of central venous catheter, proper guidance, and training of scuba divers.

Delayed systemic air embolism in a child with severe blunt chest trauma treated with high-frequency oscillatory ventilation

PURPOSE

Trauma is the leading cause of death in children over one year of age. Even with optimal field care, blunt chest trauma with hemoptysis is a potentially fatal injury due to exsanguination or arterial air embolism. Most often, cardiovascular collapse that is unresponsive to therapy develops shortly after endotracheal intubation and initiation of positive pressure ventilation. We present a case of arterial air embolism after blunt chest trauma that manifested atypically late, i.e., one hour after initiation of positive pressure ventilation.

CLINICAL FEATURES

A 13-yr-old Caucasian boy was admitted to the emergency room after he had been run over by a car. While lung protective ventilation, including high frequency oscillatory ventilation, was performed, an alveolar to pulmonary venous fistula developed. Although the complication was diagnosed quickly, involvement of the cerebral and coronary arteries resulted in irreversible cerebral damage and fatal hemodynamic collapse. Necropsy confirmed severe damage of the right pulmonary lower lobe with involvement of the pulmonary vessels.

CONCLUSION

Patients with blunt chest trauma and hemoptysis present a diagnostic dilemma with limited therapeutic options.

Acute management of vascular air embolism

Vascular air embolism (VAE) is known since early nineteenth century. It is the entrainment of air or gas from operative field or other communications into the venous or arterial vasculature. Exact incidence of VAE is difficult to estimate. High risk surgeries for VAE are sitting position and posterior fossa neurosurgeries, cesarean section, laparoscopic, orthopedic, surgeries invasive procedures, pulmonary overpressure syndrome, and decompression syndrome. Risk factors for VAE are operative site 5 cm above the heart, creation of pressure gradient which will facilitate entry of air into the circulation, orogenital sex during pregnancy, rapid ascent in scuba (self contained underwater breathing apparatus) divers and barotrauma or chest trauma. Large bolus of air can lead to right ventricular air lock and immediate fatality. In up to 35% patient, the foramen ovale is patent which can cause paradoxical arterial air embolism. VAE affects cardiovascular, pulmonary and central nervous system. High index of clinical suspicion is must to diagnose VAE. The transesophgeal echocardiography is the most sensitive device which will detect smallest amount of air in the circulation. Treatment of VAE is to prevent further entrainment of air, reduce the volume of air entrained and haemodynamic support. Mortality of VAE ranges from 48 to 80%. VAE can be prevented significantly by proper positioning during surgery, optimal hydration, avoiding use of nitrous oxide, meticulous care during insertion, removal of central venous catheter, proper guidance, and training of scuba divers.

Intrahepatic gas at postmortem computed tomography: forensic experience as a potential guide for in vivo trauma imaging

BACKGROUND

Until August 2004 there were 106 forensic cases examined with postmortem multislice computed tomography (MSCT) and magnetic resonance (MR) imaging before traditional autopsy within the Virtopsy project. Intrahepatic gas (IHG) was a frequent finding in postmortem MSCT examinations. The aim of this study was to investigate its cause and significance.

METHODS

There were 84 virtopsy cases retrospectively investigated concerning the occurrence, location, and volume of IHG in postmortem MSCT imaging (1.25 mm collimation, 1.25 mm thickness). We assessed and noted the occurrence of intestinal distention, putrefaction, and systemic gas embolisms and the cause of death, possible open trauma, possible artificial respiration, and the postmortem interval. We investigated the relations between the findings using the contingency table (chi2 test) and the comparison of the postmortem intervals in both groups was performed using the t test in 79 nonputrefied corpses.

RESULTS

IHG was found in 47 cases (59.5%). In five of the cases, the IHG was caused or influenced by putrefaction. Gas distribution within the liver of the remaining 42 cases was as follows: hepatic arteries in 21 cases, hepatic veins in 35 cases, and portal vein branches in 13 cases; among which combinations also occurred in 20 cases. The presence of IHG was strongly related to open trauma with systemic gas. Pulmonary barotrauma as occurring under artificial respiration or in drowning also caused IHG. Putrefaction did not seem to influence the occurrence of IHG until macroscopic signs of putrefaction were noticeable.

CONCLUSIONS

IHG is a frequent finding in traumatic causes of death and requires a systemic gas embolism. Exceptions are putrefied or burned corpses. Common clinical causes such as necrotic bowel diseases appear rarely as a cause of IHG in our forensic case material.

Arterielle Luftembolie nach Polytraumatisierung bei Sturz aus dem 10. Stock

We report about the case of a 20-year-old patient who fell from the tenth floor. The patient suffered multiple injuries and systemic gas embolism. He survived his injuries despite CPR, massive transfusion, development of ARDS and SIRS with minimal neurological deficit. The possible pathogenesis of the systemic gas embolism as well as the therapy are discussed. Besides stabilizing the circulation with i.v. fluids, blood transfusion and catecholamine therapy, the use of hyperbaric oxygenation was the decisive therapeutic measure.

[Arterial gas embolism originating from the lung in anaesthesia and intensive care]

We report seven cases of arterial gas embolism originating from the lung that occurred in anaesthesia and intensive care unit in the very hospital where our regional hyperbaric oxygen facility is. They complicated lung surgery or trauma and/or followed a support by positive-pressure ventilation. Diagnosis was most often delayed, because of some scepticism of the physicians confronted with a variety of clinical features. The prognosis was bad with four deaths, despite treatment with hyperbaric oxygen in three cases.

Emergency thoracotomy in thoracic trauma-a review

Thoracic trauma is one of the leading causes of death in all age groups and accounts for 25-50% of all traumatic injuries. While the majority of patients with thoracic trauma can be managed conservatively, a small but significant number requires emergency thoracotomy as part of their initial resuscitation. The procedure has been advocated for evacuation of pericardial tamponade, direct control of intrathoracic haemorrhage, control of massive air-embolism, open cardiac massage and cross-clamping of the descending aorta. Emergency thoracotomy can be defined as thoracotomy "occurring either immediately at the site of injury, or in the emergency department or operating room as an integral part of the initial resuscitation process". Following emergency thoracotomy, the overall survival rates for penetrating thoracic trauma are around 9-12% but have been reported to be as high as 38%. The survival rate for blunt trauma is approximately 1-2%. The decision to perform emergency thoracotomy involves careful evaluation of the scientific, ethical, social and economic issues. This article aims to provide a review of the current literature and to outline the pathophysiological features, technical manoeuvres and selective indications for emergency thoracotomy as a component of the initial resuscitation of trauma victims with thoracic injury.

An unusual case of early fulminant post-traumatic fat embolism syndrome

A multiple-injured patient developed a very early onset fulminant fat embolism syndrome that was partially masked by haemorrhagic shock. Despite early diagnosis by transoesophageal echocardiography and aggressive symptomatic treatment, there was a rapid evolution to death. Post mortem examination revealed the presence of both pulmonary and systemic fat emboli. This case highlights the ever present risk of masked fat embolism syndrome shortly after trauma.

Gas embolism: an exceptional complication of radial arterial catheterization

BACKGROUND

We report a rare complication of radial arterial catheterization in a 74-year-old man who had undergone retroperitoneal surgery for an infra-renal aortic aneurysm. A right subclavian venous catheter and a right radial artery catheter were inserted for hemodynamic monitoring.

RESULTS

The patient suddenly went into a coma, with dyspnea and bradycardia, 1 day postsurgery, as a result of a cerebral gas embolism produced by the accidental entry of pressurized air into the artery via the arterial catheter. Cerebral Magnetic Resonance Imaging revealed multiple, diffuse brain lesions. Six months later the patient still had a left hemiparesis and a cognitive deficit. He walks with assistance.

CONCLUSION

Misuse of an arterial catheter can lead to a severe gas embolism. The infusion system used to flush arterial catheters should be checked regularly to ensure it contains no gas.

Pulmonary air embolism in severe head injury

Entry of air into the venous system leading to intracardiac air and pulmonary air embolism (PAE) has been reported in various clinical settings such as neurosurgical interventions in the sitting position and in autopsies on patients with head and neck injuries. We report the case of a 29-year-old male who developed severe pulmonary dysfunction after severe head injury in a high-velocity car accident. Chest X-ray showed bilateral diffuse patchy infiltrates. Pneumothorax, haemothorax, pulmonary aspiration, various forms of pulmonary oedema and pulmonary contusion could be excluded. Furthermore, there was an open laceration of the frontal sinus and maxillo-facial fractures. The history of spontaneous respiration in sitting position at the scene, rapid improvement of pulmonary function within 30 h, small amounts of air in the brain parenchyma, and circulatory shock despite elevated central venous pressure in the initial phase led to the diagnosis of PAE as the primary cause of pulmonary dysfunction. The diagnostic approach and basic therapeutical principles in patients with PAE are described. In conclusion, the case presented emphasizes the importance of considering PAE as a possible cause of respiratory failure in patients with severe head injury.

Systemic air embolism after intercostal chest drain insertion and positive pressure ventilation in chest trauma

Systemic air embolism is a potentially lethal often unrecognised complication of severe chest trauma. We present a case of delayed diagnosis of cerebral air embolism in a patient with severe thoracic trauma. The initiation of positive pressure ventilation, systemic hypotension, intraparenchymal chest drains and aerial transfer to an intensive care unit were all factors contributing to the development of systemic air embolism. The common clinical features, diagnostic tests and management of systemic air emboli are discussed.

Systemic air embolism during wedge resection of the lung

IMPLICATIONS

We present a case of systemic arterial embolism during wedge resection of the lung. The importance of transesophageal echocardiographic monitoring is described.

Can one lung ventilation prevent air embolism in the lung injury victim?

The current literature indicates that patients with hilar lung injury who are receiving positive pressure ventilation are at risk for systemic air embolism, but no studies have yet tested an alternative to the current management: immediate thoracotomy and hilar clamping. We wanted to demonstrate that one lung ventilation of the uninjured lung protects against the formation of arterial air embolism in the presence of contralateral hilar lung injury.In 6 juvenile swine, the right bronchus was selectively ventilated, and ultrasound of the abdominal aorta was used to detect air emboli. The hilum of the left lung was stabbed with a scalpel; after a brief period of monitoring to detect air emboli, the tip of the endotracheal tube was withdrawn into the trachea and the left lung ventilated.Air emboli were detected in 2 animals. The air emboli did not form while the lung was isolated, but they did appear immediately when the endotracheal tube was withdrawn into the trachea. Air was also noted in the chambers of the heart and coronary arteries, and led to fibrillation and death.One lung ventilation appears to protect against arterial air embolism in unilateral hilar lung injury. (Curr Surg 57:349-353)

Emergent airway management. Indications and methods in the face of confounding conditions

Optimal airway management requires an experienced caregiver, attention to detail, and knowledge of the patient's physiology. A variety of pharmacologic agents have proved useful in obtaining a secure airway and minimizing risk to the patient. Depending on the skills of the caregiver, oral intubation has become the preferred means of airway control in most patients. Advances in technique, equipment, and pharmacology have greatly improved the art of airway management; however, there is no substitute for an experienced clinician.

Effects of blast exposure on exercise performance in sheep

BACKGROUND

The effects of blast on maximal exercise performance were investigated in sheep that were trained to perform maximal exercise.

METHODS AND RESULTS

Sheep were fully instrumented for determination of pulmonary and systemic hemodynamics. Blast exposure was administered by using a compressed air driven shock tube that was positioned to primarily produce cardiopulmonary injury. Four levels of exposure were used that were known to produce sublethal injury ranging from little or no grossly observable cardiopulmonary injury (level 1) to confluent ecchymosis of the heart, lung, or both (level 4). We evaluated maximal exercise performance 1 hour after exposure to level 1, level 2, and level 3 and 24 hours after level 3 and level 4. VO2max was not significantly decreased 1 hour after exposure to level 1 but was decreased after exposure to level 2 (29.9%) and level 3 (49.3%). Significant improvement in exercise performance was observed in 24 hours, as VO2max was not significantly decreased 24 hour after level 3. VO2max was decreased 24 hour after level 4 injury (30.8%).

CONCLUSION

Cardiovascular data collected during exercise suggested that acute cardiopulmonary injury is responsible for the exercise performance decrement observed 1 hour after exposure and that significant recovery of function is observed 24 hours after blast injury.

[Cerebral arterial air embolism associated with pneumothorax in a patient with pressure support ventilation]

A 20-year-old woman was admitted to the ICU following a road traffic accident. She had a periorbital haematoma with a normal cerebral state on CT-scan, intrahepatic and intrasplenic haematomas and several fractures of the limb that were fixed on day 3. Twenty-four hours later, she developed a cough with symptoms of decerebration The head CT-scan showed diffuse pneumocephalus suitable with cerebral air embolism and the chest X ray a right tension pneumothorax. A chest tube was inserted. Despite the lack of hyperbaric oxygen therapy the patient recovered fully. The pneumocephalus disappeared totally after 48 hours. Seven days later, CT-scan of the head with coronal slides showed an orbital floor fracture associated with an intra-orbital aerocele.

[Massive gas embolism following lung inflation for thoracic tomodensitometry in a multiple trauma patient with lung contusions]

We report a case of gas embolism into both right and left circulation in a polytrauma patient with lung contusions, revealed by thoracic CT scan showing the heart and aorta filled with gas. It followed a lung inflation with a O2/N2O mixture for about 30 seconds at a pressure of at least 40 cmH2O in order to obtain apnoea for CT scan and to recruit atelectatic territories. The presumed mechanism was the passage of the O2/N2O mixture during the lung inflation manoeuvre out of disrupted airways into torn pulmonary blood vessels and pushed back into the heart chambers. The patient recovered fully. Lung inflation manoeuvre to obtain a prolonged apnoea during CT scan examinations of thorax is contraindicated in case of thorax trauma, as it carries a risk of gas embolism.

Cardiopulmonary effects of high-impulse noise exposure

In high-energy impulse noise environments, the biomechanical coupling process between the external forces and the pathophysiology of cardiopulmonary injury is not well understood. A 12-in-diameter compressed air-driven shock tube with reflector plate was used to induce three levels of pulmonary contusion injury in a large animal model. Twenty-one anesthetized sheep were exposed to the various levels of impulse noise generated by the shock tube, with six additional sheep serving as a control group. Pathologic evaluations, performed 3 hours after exposure, showed pulmonary contusion ranging from minor petechial changes on the surface of the lung parenchyma to diffuse ecchymoses affecting as much as 60% of the lung. The gross pathologic observations of injury produced by exposure to the impulse noise produced by the shock tube were similar to those reported for blunt impact trauma or exposure to chemical or grain-dust explosions. The extent of lung injury (lung injury index) was quantitatively assessed. A semilogarithmic relationship between the lung injury index and the measured peak pressure was demonstrated. A significant linear correlation was demonstrated between lung injury index and lung weight-to-body weight ratio. Significant cardiopulmonary changes were also observed as a result of exposure to high-impulse noise. Although in most cases the degree of change was related to the severity of the injury, significant cardiopulmonary function changes were also observed in the absence of significant grossly observable pulmonary injury. Cardiac injury was indicated by decreased cardiac output and hypotension at all levels of injury and might be the result of myocardial contusion or air emboli. Pulmonary injury was demonstrated by respiratory acidosis, increases in lung resistance, and decreases in lung compliance and lung volume. Arterial PO2 appeared to be the most sensitive parameter of injury and was decreased for all measurement intervals for all exposure groups.