Noncardiac surgery brain injury: etiologic factors and prevention.

EXCERPT: During total joint arthroplasty, showers of bony spicules, marrow fat, and clot are carried by venous blood to the lungs, creating conditions not unlike those present in patients who have suffered traumatic long bone fractures. There is recent evidence that, like the fat embolism syndrome (FES), which often has a component of neurologic dysfunction, total joint arthroplasty and femoral nailing are associated with intraoperative brain embolization as determined by transcranial Doppler ultrasonography, and magnetic resonance brain imaging. Although there are good data demonstrating that intraoperative brain embolization occurs during total joint arthroplasties, the makeup and, even more importantly, the clinical significance of these emboli remain speculative. Brain microemboli resulting from cardiac surgery occur by the millions and may cause focal ischemia resulting in significant neurologic dysfunction. Our studies suggest that the major source of these microemboli is lipid droplets of the patient's fat that drip into the blood in the surgical field. This lipid-laden blood is aspirated and then returned to the patient via the cardiopulmonary bypass (CPB) apparatus. Our investigations have focused on the causes (microemboli), consequences (brain damage), and strategies for elimination of brain lipid microemboli resulting from salvaged blood collected during surgery.

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.

Hyperbaric chamber-related decompression illness in a patient with asymptomatic pulmonary sarcoidosis.

An asymptomatic 46-yr-old male sustained an acute neurologic insult, appearing during the decompression phase of a 50-m dry hyperbaric chamber dive. The right hemisyndrome was most probably related to diving, since symptoms responded rapidly to the early commenced recompression therapy. Further diagnostics revealed a previously unknown pulmonary sarcoidosis with bilateral pulmonary opacities and pleural adhesions that might have predisposed to arterial gas embolism secondary to pulmonary barotrauma. This case may illustrate a potential risk of decompression illness even during dry chamber dives in patients suffering from asymptomatic pleuro-parenchymal pulmonary disease. The value of chest X-ray in the medical assessment of fitness to dive is therefore emphasized.

Cerebral and renal embolization after lymphography in a patient with non-Hodgkin lymphoma: case report.

An unusual case of lipid embolization to brain and kidney after lymphography in a patient with non-Hodgkin lymphoma of the upper anterior mediastinum is reported. Contrast material-enhanced echocardiography demonstrated a right-to-left shunt to the left atrium without evidence of a patent foramen ovale. Echo contrast particles were transiently present within the tumor surrounding the great vessels.

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.

Cardiotomy suction: a major source of brain lipid emboli during cardiopulmonary bypass.

BACKGROUND: Brain injury remains a significant problem in patients undergoing cardiac surgery assisted by cardiopulmonary bypass (CPB). Autopsy brain specimens of patients after cardiac operations with CPB reveal numerous acellular lipid deposits (10 to 70 microm) in the microvasculature. We hypothesize that these small capillary and arterial dilatations result from a diffuse inflammatory response to CPB or from emboli delivered by the bypass circuit. This study was undertaken to determine which aspect of CPB is most clearly associated with these dilatations. METHODS: Thirteen dogs were studied in four groups: group I (n = 3), right-heart CPB; group II (n = 2), lower-extremity CPB; group III (n = 3), hypothermic CPB; and group IV (n = 5), hypothermic CPB with cardiotomy suction. All dogs in all groups were maintained on CPB for 60 minutes and then euthanized. Brain specimens were harvested, fixed in ethanol, embedded in celloidin, and stained with the alkaline phosphate histochemical technique so that dilatations could be counted. RESULTS: All dogs completed the protocol. The mean density of dilatations per square centimeter for each group was as follows: group I, 1.77 +/- 0.77; group II, 4.17 +/- 1.65; group III, 4.54 +/- 1.69; and group IV, 46.5 +/- 14.5. In group IV (cardiotomy suction), dilatation density was significantly higher than in group III (hypothermic cardiopulmonary bypass) (p = 0.04) and all other groups (p = 0.04). CONCLUSIONS: Blood aspirated from the surgical field and subsequently reinfused into dogs undergoing CPB produces a greater density of small capillary and arterial dilatations than CPB without cardiotomy suction, presumably because of lipid microembolization.

Coffee consumption in hypertensive men in older middle-age and the risk of stroke: the Honolulu Heart Program.

OBJECTIVE: To examine the association between coffee consumption and the development of stroke in men at high risk for cardiovascular disease. METHODS: Coffee intake was observed from 1965 to 1968 in a cohort of men enrolled in the Honolulu Heart Program with follow-up for incident stroke over a 25-year period. Subjects were 499 hypertensive men (having systolic or diastolic blood pressures at or above 140 and 90 mm Hg, respectively) in older middle-age (55 to 68 years) when follow-up began. Past and current cigarette smokers were excluded from follow-up. RESULTS: In the course of follow-up, 76 men developed a stroke. After age-adjustment, risk of thromboembolic stroke increased significantly with increases in coffee consumption (P = 0.002). No relationships were observed with hemorrhagic stroke. When adjusted for other factors, the risk of thromboembolic stroke was more than doubled for men who consumed three cups of coffee per day as compared to nondrinkers of coffee (RR = 2.1; 95% CI = 1.2-3.7). CONCLUSIONS: Although in need of further confirmation, consumption of coffee appears to be positively associated with an increased risk of thromboembolic stroke in hypertensive men in older middle-age. Findings suggest that it may be prudent to advise older middle-aged men with hypertension who consume large amounts of coffee to consider reducing their coffee intake.

Influence of garlic compared to aspirin on induced photothrombosis in mouse pial microvessels, in vivo.

Effect of garlic on photochemically-induced platelet aggregation in pial microvessels of the mouse, in vivo, was compared to that of acetyl salicylic acid (ASA). Three trials were carried out, in which garlic at doses of 12.5, 25, 50 and 100 mg/kg and ASA doses of 25, 50 and 100 mg/kg were used. Each trial included treatment groups of male mice, approximately 30 g, and a control group. Animals were anesthetized (urethane, 1-2 mg/g, i.p.), the trachea was intubated and a craniotomy was performed. Induction of platelet aggregation was made by activation of circulating sodium fluorescein (0.1 ml of 5% solution/25 g, i.v.) with an intense mercury light. Garlic, ASA and vehicle solutions were injected, i.p., 60 min prior to the photochemical insult. The time for the first platelet aggregate to appear in pial arterioles was significantly delayed (P < 0.001) only by the 100 mg/kg garlic dose and by all ASA doses. The effect of this garlic dose on first aggregate was comparable to that of the 25 and 50 mg/kg ASA doses. Only the ASA doses delayed (P < 0.05) the appearance of first aggregate in venules. Arteriolar and venular diameter changes were not different among groups of all trials. Data of this study documented that garlic was capable of delaying platelet aggregation in mouse pial arterioles, in vivo.

[A novel photochemical model of the middle cerebral artery for thrombosis research and evaluation of anti-thrombotic agents].

We have established a novel thrombosis model of the middle cerebral artery (MCA). The thrombotic occlusion of the MCA was induced by the photochemical reaction between Rose Bengal and green light, which causes endothelial injury followed by platelet adhesion, aggregation and formation of a platelet and fibrin-rich thrombus at the site of the photochemical reaction. With this model, we have investigated the effects of anti-thrombotic agents, thrombolytic agents and neuroprotective agents. In our model, ADP, thromboxane A2 (TXA2) and thrombin play a key role in thrombus formation of the MCA. Tissue-type plasminogen activator (tPA) could cause an opening of the thrombotic MCA occlusion and reduced the size of the cerebral infarction. Furthermore, a TXA2 antagonist enhanced the thrombolytic efficacy of tPA. MS-153 ((R)-(-)-5-methyl-1-nicotinoyl-2-pyrazoline), a glutamate release inhibitor and YM90K [6-(1 H-imidazol-1-yl)-7-nitro-2,3(1H, 4H)-qunoxalinedione monohydrochloride, an alpha-amino-3hydroxy-5methyl-4-isoxazole (AMPA) antagonist reduced the cerebral infarction 24 hr after the MCA occlusion. This model is very useful for investigating the mechanisms of anti-thrombotic and neuroprotective agents and evaluating the effects of these agents.

Clinically silent microemboli in patients with artificial prosthetic aortic valves are predominantly gaseous and not solid.

BACKGROUND AND PURPOSE: Microembolic signals (MES) are frequently observed by transcranial Doppler ultrasound after prosthetic heart valve implantation. Whether these MES are due to solid or gaseous particles is uncertain. We hypothesized that MES are gaseous and that if they are due to cavitation effects, their occurrence should respond to changes of dissolved oxygen concentration in the blood. METHODS: Transcranial monitoring of MES was performed in five patients with prosthetic aortic valves, who inspired 100% oxygen through a facial mask. In one patient 100% oxygen was administered under hyperbaric (2.5 kPa) conditions in a hyperbaric chamber. RESULTS: Inspiration of 100% oxygen reduced the total number of MES from 96/30 min to 2/30 min. Increasing the concentration of dissolved oxygen in the hyperbaric chamber led to an increase from 0.3 MES per minute (1.0 kPa) to 0.9 MES per minute (2.5 kPa). CONCLUSIONS: The dependence of occurrence of MES in patients with prosthetic cardiac valves on the oxygen partial pressure in blood provides strong evidence that these microemboli are gaseous.

[Sickle cell anemia and internal cerebral vein thrombosis]. / Drépanocytose et thrombose des veines cérébrales internes.

Cerebrovascular disorders are frequently associated with sickle cell disease, mainly in homozygous children. We report the case a 25-old-patient with known sickle cell disease who presented with coma inaugurated by manifestations of intracranial hypertension. CT revealed bilateral thalamic infarcts and angiography confirmed the thrombosis of internal cerebral veins. Treatment included heparin and blood transfusion. Severe cerebral oedema resulted in the lethal outcome three days later.

[The role of preparation LB in forming a thrombotic infarct of the cerebral cortex]. / Rol' preparata LB v formirovanii tromboticheskogo infarkta kory bol'shogo mozga.

Non-invasion model for photochemically induced brain infarction was used to study the effect of a the new anti-ischemic drug LB ("Plaferon") in albino rats. Intensity of a local blood flow was measured so as oxygen tension in brain cortex. Square and volume of the disturbed nervous tissue region, capillary length and density of distribution of different caliber vessels were detected by means of light microscopy in serial sections of brain cortex. Preliminary introduction of LB was found to prevent formation of thrombotic infarction (the volume of cortical zone damaged is 85% lower as compared to the control). Anti-ischemic effect of LB implicates in vasodilatory action on cerebral vessels and also breaking pathogenic chain of ischemia development.

Delayed presentation of cerebral arterial gas embolism following proven intraoperative venous air embolism.

We describe the case of a 33-year-old woman who suffered a delayed-onset arterial gas embolism following a significant venous air embolism during surgery to remove an acoustic neuroma. We report the management of the problem and discuss the mechanisms by which this event might have occurred.

Arterial gas embolism following a 1-meter ascent during helicopter escape training: a case report.

We present the case of a helicopter pilot who suffered an arterial gas embolism following instruction in the use of the Short Term Air Supply System (STASS) at a depth of 1 m of water. This is believed to be the shallowest depth from which a case of arterial gas embolism associated with the use of compressed air breathing apparatus has been reported.