Pulmonary cyst and cerebral arterial gas embolism in a hypobaric chamber: a case report

This is a report of an aircrew member who suffered a serious physiological incident in the form of pulmonary barotrauma and cerebral arterial gas embolism during hypobaric chamber training, and who subsequently was shown to have a cyst in the upper lobe of the left lung. The likely origin of the cyst is discussed, as well as the aeromedical disposition following thoracotomy and apical segmentectomy to remove the cyst.

Hemodilution during venous gas embolization improves gas exchange, without altering V(A)/Q or pulmonary blood flow distributions

BACKGROUND

Isovolemic anemia results in improved gas exchange in rabbits with normal lungs but in relatively poorer gas exchange in rabbits with whole-lung atelectasis. In the current study, the authors characterized the effects of hemodilution on gas exchange in a distinct model of diffuse lung injury: venous gas embolization.

METHODS

Twelve anesthetized rabbits were mechanically ventilated at a fixed rate and volume. Gas embolization was induced by continuous infusion of nitrogen via an internal jugular venous catheter. Serial hemodilution was performed in six rabbits by simultaneous withdrawal of blood and infusion of an equal volume of 6% hetastarch; six rabbits were followed as controls over time. Measurements included hemodynamic parameters and blood gases, ventilation-perfusion (V(A)/Q) distribution (multiple inert gas elimination technique), pulmonary blood flow distribution (fluorescent microspheres), and expired nitric oxide (NO; chemoluminescence).

RESULTS

Venous gas embolization resulted in a decrease in partial pressure of arterial oxygen (PaO2) and an increase in partial pressure of arterial carbon dioxide (PaCO2), with markedly abnormal overall V(A)/Q distribution and a predominance of high V(A)/Q areas. Pulmonary blood flow distribution was markedly left-skewed, with low-flow areas predominating. Hematocrit decreased from 30+/-1% to 11+/-1% (mean +/- SE) with hemodilution. The alveolar-arterial PO2 (A-aPO2) difference decreased from 375+/-61 mmHg at 30% hematocrit to 218+/-12.8 mmHg at 15% hematocrit, but increased again (301+/-33 mmHg) at 11% hematocrit. In contrast, the A-aPO2 difference increased over time in the control group (P < 0.05 between groups over time). Changes in PaO2 in both groups could be explained in large part by variations in intrapulmonary shunt and mixed venous oxygen saturation (SvO2); however, the improvement in gas exchange with hemodilution was not fully explained by significant changes in V(A)/Q or pulmonary blood flow distributions, as quantitated by the coefficient of variation (CV), fractal dimension, and spatial correlation of blood flow. Expired NO increased with with gas embolization but did not change significantly with time or hemodilution.

CONCLUSIONS

Isovolemic hemodilution results in improved oxygen exchange in rabbits with lung injury induced by gas embolization. The mechanism for this improvement is not clear.

Diving and marine medicine review part II: diving diseases

Diving is a high-risk sport. There are approximately between 1 to 3 million recreational scuba divers in the USA (with over a quarter-million learning scuba annually); there are about 1 million in Europe and over 50,000 in the United Kingdom. In this population 3-9 deaths/100,000 occur annually in the US alone, and those surviving diving injuries far exceeds this. Diving morbidity can be from near-drowning, from gas bubbles, from barotrauma or from environmental hazards. In reality, the most common cause of death in divers is drowning (60%), followed by pulmonary-related illnesses. The mean number of annual diving fatalities in the USA from 1970 to 1993 was 103.5 (sd 24.0) and the median was 106. This article will focus primarily upon pressure effects on the health of a diver. There are two principle ways pressure can affect us: by direct mechanical effects and by changing the partial pressures of inspired gases. Dysbarism is a general term used to describe pathology from altered environmental pressure, and has two main forms: barotrauma from the uncontrolled expansion of gas within gas-filled body compartments and decompression sickness from too rapid a return to atmospheric pressure after breathing air under increased pressures. Greater than 90% of the human body is either water or bone, which is incompressible; the areas directly affected by pressure changes thus are those that are filled with air or gas. These sites include the middle ear, the eustachian tube, the sinuses, the thorax, and the gastrointestinal tract. Air in these cavities is compressed when the ambient pressure rises because the pressure of inhaled air must equilibrate with the ambient pressure.

Pulmonary venous air embolism following accidental patient laceration of a hemodialysis catheter

As the number of patients at home with indwelling central venous catheters increases, more complications from their use will present to the emergency department. We report a case of pulmonary venous air embolism after a patient inadvertently severed the distal few centimeters of an indwelling central venous catheter.

Air embolism after intravenous injection of contrast material

Venous air embolism, though considered rare, occurs more frequently than it is recognized. We report the case of a 54-year-old man who was incidentally found to have air in the left brachiocephalic vein and right ventricle after contrast-enhanced computed tomography (CT). Air embolism has been noted to occur after contrast-enhanced CT examination in up to 23% of patients. Because these emboli are small to moderate size and are usually venous, the patients are usually asymptomatic. We review the pathophysiology of air embolization and the recommended treatment.

[Arterial air embolism as a complication of blunt thoracic trauma]

Systemic air embolism is a dramatic event frequently resulting in death. The clinical manifestations are polymorphic and unspecific. We report a case of a systemic air embolism in a patient with lung contusion. We wish to arouse a sensibility for this clinical picture, which seems to be underestimated in its frequency and importance, and discuss concepts of mechanical ventilation in patients with blunt thoracic trauma.

Cerebral arterial gas embolism in air force ground maintenance crew--a report of two cases

Two cases of cerebral arterial gas embolism (CAGE) occurred after a decompression incident involving five maintenance crew during a cabin leakage system test of a Hercules C-130 aircraft. During the incident, the cabin pressure increased to 8 in Hg (203.2 mm Hg, 27 kPa) above atmospheric pressure causing intense pain in the ears of all the crew inside. The system was rapidly depressurized to ground level. After the incident, one of the crew reported chest discomfort and fatigue. The next morning, he developed a sensation of numbness in the left hand, with persistence of the earlier symptoms. A second crewmember, who only experienced earache and heaviness in the head after the incident, developed retrosternal chest discomfort, restlessness, fatigue and numbness in his left hand the next morning. Both were subsequently referred to a recompression facility 4 d after the incident. Examination by the Diving Medical Officer on duty recorded left-sided hemianesthesia and Grade II middle ear barotrauma as the only abnormalities in both cases. Chest X-rays did not reveal any extra-alveolar gas. Diagnoses of Static Neurological Decompression Illness were made and both patients recompressed on a RN 62 table. The first case recovered fully after two treatments, and the second case after one treatment. Magnetic resonance imaging (MRI) of the brain and bubble contrast echocardiography performed on the first case 6 mo after the incident were reported to be normal. The second case was lost to follow-up. Decompression illness (DCI) generally occurs in occupational groups such as compressed air workers, divers, aviators, and astronauts. This is believed to be the first report of DCI occurring among aircraft's ground maintenance crew.

Paradoxical air embolism during orthoptic liver transplantation: diagnosis by transoesophageal echocardiography

We describe a case of paradoxical air embolism during orthotopic liver transplantation, early diagnosis, using intra-operative transoesophageal echocardiography after a circulatory failure, allowed early management by hyperbaric oxygen therapy.

Anaesthetic implications of thoracoscopic surgery in children

As the equipment and technique have improved, minimally invasive surgery is being applied to younger and younger children. With the advent of this valuable surgical technique, there are also specific modifications necessary in the anaesthetic technique. When considering the anaesthetic implications of these patients, one must account for both the patient's underlying status as well as physiological derangements induced by the surgical procedure. The following article attempts to address and review the specific anaesthetic implications of thoracoscopic procedures in neonates, infants, and children including the preoperative evaluation, intraoperative care and monitoring, and postoperative issues including analgesia. The techniques of one-lung anaesthesia, commonly required for thoracoscopy, are reviewed as well as consideration of the adverse effects which can occur during thoracoscopy including inadvertent intravascular CO2 embolism.

Hyperbaric oxygen therapy for massive arterial air embolism during cardiac operations

BACKGROUND

Massive arterial air embolism is a rare but devastating complication of cardiac operations. Several treatment modalities have been proposed, but hyperbaric oxygen is the specific therapy.

METHODS

The Israel Naval Medical Institute is the only referral hyperbaric center in this country for acute care patients. We reviewed our experience in the hyperbaric oxygen treatment of massive arterial air embolism during cardiac operations.

RESULTS

Seventeen patients were treated between 1985 and 1998. Eight patients (47.1%) experienced a complete neurologic recovery; 6 patients (35.3%) remained unconscious at discharge, and 3 patients (17.6%) died. Mean (+/- SD) delay from the end of the operation to hyperbaric therapy was 9.6 +/- 7.4 hours (range, 1-20 hours). This delay was 4.0 +/- 3.4 hours (1-12 hours) for patients who had a full neurologic recovery, 12.8 +/- 7.1 hours (5-20 hours) for patients with severe neurologic disability, and 18.0 +/- 2.0 hours (16-20 hours) for patients who died (1-way analysis of variance; P =.002). The source of variance among the groups mainly resulted from the short delay for patients who experienced complete recovery compared with the other 2 groups (Tukey test). All 5 patients who were treated within 3 hours from the operation and 50% (2 of 4 patients) of those patients treated 3 to 5 hours from operation experienced a full neurologic recovery. With a delay of 9 to 20 hours, only 1 of 8 patients had a full neurologic recovery. The association between outcome and treatment delay was found to be statistically significant (tau = 0.65 with exact 2-sided P value =.0007).

CONCLUSION

Hyperbaric oxygen therapy should be administered as soon as possible after massive arterial air embolism during cardiac operations.

Hyperbaric oxygen therapy in the pediatric patient: the experience of the Israel Naval Medical Institute

The pediatric patient is to be found in hyperbaric facilities throughout the world, receiving hyperbaric oxygen (HBO) therapy for both life-threatening and chronic diseases.

OBJECTIVE

To review the experience accumulated at the Israel Naval Medical Institute in the treatment of pediatric patients.

DESIGN

A retrospective analysis and review of all records of patients younger than age 18 years.

RESULTS

Between 1980 and 1997, 139 pediatric patients age 2 months to 18 years (mean, 7.7 years) received HBO treatment at the Israel Naval Medical Institute. Of the children, 111 (79%) suffered from acute carbon monoxide (CO) poisoning; 13 (9.2%) were treated after crush injury, traumatic ischemia, or compartment syndrome; 4 (2.8%) had clostridial myonecrosis; 1 (0.7%) had necrotizing fasciitis; 5 (3.6%) had refractory osteomyelitis; 2 (1.4%) had suffered massive air embolism; 2 (1.4%) had purpura fulminans; and 1 (0.7%) suffered from decompression sickness. Outcome, judged by neurologic sequelae, mortality, and extent of soft tissue loss and limb amputation, was favorable in 129 patients (93%). Two patients (1.4%) died, 1 as a result of CO poisoning and the other, gas gangrene; 2 of the patients in the CO group (1.4%) remained with neurologic sequelae, and 6 patients in the acute traumatic ischemia group (4.3%) underwent limb amputation.

CONCLUSIONS

We had a favorable experience with 129 of a total 139 pediatric patients treated at our facility for the indications listed. A basic knowledge of HBO therapy is needed to refer the pediatric patient for treatment when indicated. The needs of the pediatric patient, especially the critically ill, require specific skills and equipment inside the hyperbaric chamber. Close collaboration between the pediatrician and the hyperbaric medicine physician is essential to ensure adequate care for infants and children.

[Coronary gas embolism after laparoscopic surgery]

Gas embolism is a severe complication of laparoscopic surgery. We report two cases: one with lethal peroperative cardiac arrest from massive coronary artery gas embolism recognized during open-chest cardiac massage; the second case, also associated with coronary artery gas embolism, resulted in severe but transient abnormal left ventricular anterior wall motion, subepicardial ischaemia and injury in ECG leads V1 to V5, but unremarkable coronary arteriography and full recovery. The pathophysiology of gas embolism occurring during a laparoscopic procedure, the mechanisms of gas entry into the systemic vascular bed, the clinical, ECG, pulse oximetry, end-tidal CO2 concentration changes and alarm signs are discussed. The diagnostic value of Doppler transoesophageal echocardiography when possible is underlined, and emergency management of gas embolism is considered.

[Gas embolism during endonasal YAG laser surgery]

The authors describe a case of air embolism during an endonasal YAG laser surgery in a 10-year-old child. This accident was caused by the coaxial air cooling system of the laser ruby tip. The importance of end tidal CO2 monitoring and precordial auscultation during laser surgery even in patients without risk factors is underlined.

Acute cerebral gas embolism from hydrogen peroxide ingestion successfully treated with hyperbaric oxygen

CASE REPORT

We present a case of an adult who suffered an apparent stroke shortly after an accidental ingestion of concentrated hydrogen peroxide. Complete neurologic recovery occurred quickly with hyperbaric therapy. Hydrogen peroxide can produce acute gas embolism. Hyperbaric therapy is the definitive treatment for gas embolism from hydrogen peroxide ingestion as it is for all other causes of acute gas embolism. This is the first case reported in the literature of hyperbaric therapy used successfully to treat cerebral gas embolism caused by hydrogen peroxide.

Anesthetic considerations in neonatal neurosurgical patients

Neonatal neurosurgery patients have specific considerations throughout the perioperative course in addition to the usual care of neonates undergoing other surgical procedures. Prematurity, with its associated comorbidity, temperature, and glucose control are important topics to consider in this age group. This article addresses practical aspects of preoperative assessment, intraoperative management, and postoperative care. Because CSF shunting and myelomeningocele repair are common neonatal procedures, these specific procedures are the focus of this article.

Venous air embolism during orthotopic liver transplantation in a child

PURPOSE

A first case of massive venous air embolism is reported as a complication of orthotopic liver transplantation in a 17-month-old child during the dissection phase.

CLINICAL FEATURES

During the hepatic dissection phase, perforation of suprahepatic veins was responsible for an air embolism with a decrease of P(ET)CO2 (27 to 6 mmHg), hypoxaemia (SpO2 decreased from 100 to 88%), and haemodynamic instability (systolic blood pressure decreased from 85 to 50 mmHg, central venous pressure increased from 6 to 10 mmHg). Central venous aspiration of air was unsuccessful but immediate resolution occurred and neurological outcome was normal.

CONCLUSION

Venous air embolism during the dissection phase of liver transplantation in children is a risk that should be considered

Neurological manifestation of arterial gas embolism following standard altitude chamber flight: a case report

In the course of a decompression at flight level 280 (28,000 ft) in an altitude chamber flight, a 45-yr-old cabin air traffic controller developed sudden numbness in his left upper and lower extremities and, soon after, complete paralysis in the left side, dysarthria and left facial palsy. A presumptive diagnosis of arterial gas embolism (AGE) was made and hyperbaric oxygen therapy (HBO) was given after airevac of the patient to the closest compression facility. Complete resolution of the symptoms was obtained after treatment Table VI-A (extended), plus 3 consecutive HBO treatments (90 min of Oxygen at 2.0 ATA). AGE is a rare event in the course of regular altitude chamber flight and diagnosis should be done in the context of the barometric pressure changes and an acute cerebral vascular injury. Risk factors and follow-up diagnostic procedures are discussed.