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Objective: We conducted the current study to evaluate the removal rate of air embolism from cerebral arteries after spontaneous breathing at a low FIO2 in comparison with mechanical ventilation at an FIO2 of 1.0., Design: Randomized, experimental trial., Setting: Neuroimaging department at a veterinary school hospital laboratory., Subjects: Nine anesthetized beagles undergoing mechanical ventilation with previous normal cranial computed tomography (CT) scan., Interventions: In each dog, after a control scan, air was infused at a constant flow rate, via a catheter inserted into the internal carotid artery. CT scan was repeated until typical bubbles appeared. Immediately after, the animals were randomly assigned to breathe room air (group A), or to be mechanically ventilated at an FIO2 of 1.0 (group B). CT scan was again repeated every minute until the removal of all bubbles. We compared the volume of air infused per kg of body and brain weights, the lowest density among bubbles (Hounsfield units), the duration of radiologic findings, and the ratio of volume/duration (mL/kg/min) between the two groups, using the Mann-Whitney test., Results: The volume of air infused per kg of body and brain weights and density were not significantly different between the two groups. The duration of radiologic findings was shorter (p < .02) in group B (7.0 +/- 4.7) than in group A (20.4 +/- 3.8), and the air removal rate from cerebral arteries (expressed as volume/duration of radiologic findings) was dramatically improved (p < .02) in group B (0.159 +/- 0.042) in comparison with group A (0.046 +/- 0.016)., Conclusions: These results suggest that the removal rate of air from cerebral arteries is dramatically increased by mechanical ventilation at an FIO2 of 1.0. Consequently, the time of cerebral ischemia may be decreased, but the result does not account for the effects of each factor separately. Further studies are required to evaluate the clinical benefits of high FIO2 administration and of mechanical ventilation separately. However, the prompt application of mechanical ventilation with an FIO2 of 1.0 may be recommended when air embolism is suspected.

An adult male sustained a number of stab injuries and other injuries including a fatal stab injury to the neck. There was evidence of air embolism which was considered to be a major factor causing death. The discussion is in four parts. Part I is confined to the post mortem examination. Part II relates to the medico-legal aspects of the case. Part III is a general discussion on embolism and its medico-legal significance whilst Part IV is on the medico-legal aspects of air embolism.

This is the case of a young pregnant black woman who died during foreplay when her male partner with his hands accidentally forced air from her vaginal cavity into her uterine cavity, causing air embolization in the veins on the surface of her heart and her brain. Her premature infant was removed by cesarean section by emergency-room personnel after she died. The infant survived for 12 days before being declared brain dead.

Systemic arterial air embolism is frequently unrecognized as a cause of death among patients with isolated penetrating lung injury. Between 1975 and 1983 at Parkland Memorial Hospital, the complication of systemic arterial air embolism developed in 9 patients with penetrating lung injury (six gunshots and three stabbings). Eight patients were either in profound shock or experienced cardiac arrest and all were intubated and on positive-pressure ventilation, frequently on a manual resuscitator bag before or at the time of diagnosis. The diagnosis was made by direct visualization of air in the coronary vessels in all 9 patients, and in 3 air was also aspirated from the left ventricular apex and aortic root. In addition, 5 patients had clinically significant hemoptysis. At operation, only an isolated injury to the lung was found in 7 of the 9 patients. Arterial air embolism is a highly lethal complication; 6 of our patients died, a mortality rate of 66%. Thus, it clearly behooves us to be more alert to the possible occurrence of this complication among all victims of penetrating chest trauma. We must accept that systemic arterial air embolism is an established complication of penetrating lung injury and must recognize that it occurs much more frequently than has been previously reported. Prompt diagnosis coupled with aggressive efforts at cardiopulmonary resuscitation is crucial for successful management of patients with air embolism.

We present two cases of fatal venous air embolism that occurred in previously healthy adolescents during posterior spine fusion and instrumentation for scoliosis. Previously recorded cases in the literature have been rare and only briefly discussed. Air embolism has been a complication noted in the anesthesia and neurosurgical literature, occurring primarily in total hip patients and those patients undergoing neurosurgical procedures in a sitting position. An examination of the pathophysiology of air embolism in posterior spinal procedures would indicate the use of properly placed central lines and end-expiratory CO2 monitoring as the primary modes of detection and treatment considering the potentially fatal risk factors for spinal patients.

There were 132 maternal deaths in British Columbia in the years 1963 to 1970. The mean maternal mortality rate for these eight years was 0.317. Sixty of these deaths (45.5%) were due to direct obstetrical causes. Indirect and nonrelated deaths accounted for 21.2 and 33.3% of the total, respectively. The most common causes of direct obstetrical deaths were hemorrhage, infection and vascular accidents, in that order; pre-eclampsia ranked a distant fourth. Ninety-five percent of direct obstetrical deaths were probably avoidable. Approximately 27% of all direct obstetrical deaths were abortion-related. Hemorrhage continues to be a major problem, in particular among the native Indian women of the province.If further reduction in maternal mortality is to be achieved, obstetrical hemorrhage must be better managed and deaths due to abortions reduced. Future studies should reveal if the liberalized abortion laws will assist in the realization of the latter goal.

The charts of 61 patients treated from 1970 through 1981 were reviewed to determine the clinical outcome after treatment of air embolism from blunt (15 patients) and penetrating (21 gunshot and 25 stabbing) thoracic injuries. The diagnosis of air embolism was confirmed by the presence of air in the coronary arteries (57%), air aspirated from the heart (30%) or major artery (10%), or Doppler findings (3%). All patients were in shock or cardiac arrest, and in 36% of these patients there were early signs of hemoptysis or unexpected arrest after intubation and positive-pressure ventilation. Successful management included (1) early thoracotomy for diagnosis as well as for specific treatment, (2) hilar cross-clamping for control of bronchovenous communication, (3) maintenance of perfusion pressures with fluids, vasopressors, or aortic cross-clamping, and (4) prompt correction of the embolic source, usually a lung resection. The overall survival rate was 44%, which correlated with the mechanism of injury, with associated nonthoracic injuries, and with the occurrence of arrest in a controlled setting. We conclude that (1) air embolism can insidiously occur even in blunt trauma; (2) suspicion should be high with hemoptysis or unexpected arrest; and (3) successful treatment includes immediate thoracotomy for diagnosis, resuscitation, and prompt control of the bronchovenous communication.

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.

A relatively high number of fatal complications during hysteroscopy, where carbon dioxide was used as the uterine distension medium, plus a recent report on heart embolism during dog experiments with venous carbon dioxide infusion, audible by simple stethoscopic surveillance during the infusion, prompted the present study. Seventy women with no history of cardiac valvular disease or failure were observed during carbon dioxide hysteroscopy for the occurrence of the characteristic metallic heart sound caused by the intracardiac presence of free carbon dioxide during the heart contractions. In seven cases (10%) the typical metallic heart sounds appeared during the hysteroscopy, leading to immediate interruption of the hysteroscopy and withdrawal of the hysteroscope. This caused the pathological heart sounds to disappear, after which the hysteroscopy could continue. Heart auscultation should always be performed during carbon dioxide hysteroscopy in order to avoid serious cardiovascular complications. This simple precaution turns carbon dioxide hysteroscopy into a versatile and safe method for intra-uterine diagnosis and therapy.

A case of fatal air embolism caused by pneumatosis cystoides intestinalis is presented. To our knowledge, there has been no previous report of fatal air embolism associated with this disease. The underlying pathology was not known premortem and the finding of air both in the mesenteric venous bed and in the right side of the heart is consistent with a collateralizing phenomenon due to portal vein obstruction.

In 74 mongrel dogs 0.02 ml air/kg of body weight was injected into the left anterior descending coronary artery (LAD). Forty-three dogs were studied without (group I) and 31 with (group II) extracorporeal circulation (ECC). Time course and extent of myocardial ischemia were assessed by continous thermographic measurements as well as by fluorescence techniques. Coronary air embolism resulted in an immediate decrease of myocardial temperature associated with transmural ischemia. In 31 surviving dogs (72%) of group I this phenomenon was fully reversible within 8.7 minutes as compared with 5.4 minutes in 100% of the surviving dogs from group II. No postembolic death occurred in the group II animals. In group II the postembolic temperature decrease was significantly less than that in group I, and, in addition, the myocardial area involved was significantly smaller. The results indicate that the extent of myocardial ischemia following coronary air embolism and its time course can be well-documented by means of thermocardiography; using extracorporeal circulation survival can be improved and myocardial damage minimized.

Although deaths that take place during the course of an operation are commonly called "Death under the Anaesthetic", they did occur before the advent of anaesthesia and in 1824 Dupuytren listed seven posssible causes. Thirty-three reported cases are mentioned and compared with Dupuytren's list. Air embolism was the commonest cause. The last survey in 1956 suggested that anaesthesia was entirely responsible for about 60 per cent of cases and surgery for 10 per cent.

A comparison of the various methods available for the detection of air embolus has been carried out in patients undergoing posterior fossa exploration in the sitting position. A group of 17 patients (Group A) was comprehensively monitored by a central venous catheter, an infra-red carbon dioxide analyser and a Doppler ultrasonic flow transducer in addition to more traditional clinical methods. Group B (19 patients) was monitored by commonly used clinical methods consisting of continuous palpation of the radial pulse, intermittent blood pressure measurement, the use of an oesophageal stethoscope and the electrocardiograph. In Group A the detection of air embolus varied from 6% using an oesophageal stethoscope to 58% by the Doppler method. In Group B air embolus was diagnosed in 10% of patients. One patient in each group died from air embolus; one patient had a paradoxical embolus to the coronary arteries. It is concluded that comprehensive monitoring for air embolus, including the use of Doppler ultrasound, is an essential part of the management of these patients, for both diagnosis and treatment.

A young woman died suddenly about 1 hour after instillation of CO2 for diagnostic larparoscopy. Post-mortem x-rays revealed large volumes of gas in the portal system, the heart, and the brain. In addition, autopsy revealed gas bubbles in the coronary arteries, pulmonary hemorrhage and edema, and a probe-patent foramen ovale. We postulated the "trapping" of gas in the portal circulation and affirmed this by experiments in 6 dogs. We further postulate the delayed and intermittent release of this gas and of platelet aggregates into the systemic circulation would occur in volumes which would be insufficient to produce hemodynamic signs yet sufficient to produce serious pulmonary insult.

According to the literature data lethal air embolie occured several times at interruptions of pregnancy carried out by vacuum-aspiration. The question was investigated whether complications were brought about by the method itself or were the fatal consequencies of some technical faults. At the vacuum aspiration the triggering mechanism for air-embolie is absent. On the basis of the reports being evaluable at our disposal we found that more than the half of the lethal air-embolies were caused by medical technical errors which could have been avoided with more precaution. In the other cases the medical technical errors could not be proved but adequate explanations for the lethal cases are missing. Carrying out the operations with thoroughful care and taking into consideration more strictly all precautionary measures there is no reason for fearing of lethal air-embolie.

Air embolism following penetrating lung trauma has been reported infrequently and its existence is questioned. A death resulting from air embolism following a high-velocity gunshot wound is presented. Appropriate treatment and preventive measures are discussed.

A case of fatal air embolism during transurethral resection is presented along with suggestions for treatment. The importance of prompt recognition of the condition is stressed.

An investigation of 30 recorded deaths in sport diving in California in 1970 gave evidence of equipment failure in two, a failure of the victims' judgment or training in 13, and a failure of rescue attempts in four instances. In three histories no cause could be found. Factors associated with the deaths are reported. In the same period there were recorded in the state 171 drownings in home pools out of a total of 712 drownings in water sports.

In Los Angeles County, almost one-third of abortion deaths are due to gas embolus. Whenever a gas or a gas-producing liquid is injected into a pregnant uterus, a fatal gas embolus is possible because the utero-placental bed is an open avenue to the maternal circulation. The usual sequence of events is collapse, rapidly followed by death. By the time the rescue squad is summoned, the patient is either dead or beyond possibility of resuscitation. In the six years 1962-1967 there were 27 gas embolus deaths associated with abortion in the Los Angeles area. All the women were the victims of ignorance or indifference. Wider public knowledge of this lethal danger is the only means by which mortality can be reduced.