Retrograde venous cerebral air embolism from disconnected central venous catheter: an experimental model

There are few reported cases of death attributed to retrograde cerebral air embolism from central venous catheter. The pathophysiological mechanism and the necessary conditions are not fully understood, also because of missing experimental data. We performed experimental simulation while working on a possible case of retrograde cerebral air embolism. A hermetic system consisting of two containers connected to each other and to an electric pump by means of rubber hoses was built. In this system, a fluid (water and blood) could continuously flow under conditions similar to those of the common jugular vein. The part of the system representing the jugular vein could be freely positioned at angles between 0 and 90°. A central venous catheter was inserted into this part. After disconnection, the behavior of the air bubbles entering the hose through the tip of the catheter was evaluated at different positions. At angles between 0 and 45°, the air bubbles followed the fluid flow. At angles >45°, the air bubbles showed the tendency to flow upstream; this phenomenon was more evident the more vertically the hose was located. We were able to demonstrate that a retrograde air embolism can be caused by a disconnected catheter and is even more likely if the neck is in a vertical position.     

Fatal pulmonary cement embolism following percutaneous vertebroplasty (PVP)

A case of fatal pulmonary embolism with acrylic cement occuring during a percutaneous vertebroplasty on account of a fracture of L1 is described. Autopsy confirmed the presence of large amounts of surgical cement in the paravertebral venous system and in the pulmonary arteries. This rare complication occurred because perivertebral venous cement migration was not recognized during vertebroplasty. To our knowledge, this is the first case of fatal pulmonary embolism caused by surgical cement following a percutaneous vertebroplasty.     

肺动脉栓塞致死23例法医学分析

目的总结分析肺动脉栓塞致死的一般特点,探讨法医病理学鉴定要点及注意事项。方法对2001~2011年在中山大学法医鉴定中心鉴定的23例肺动脉栓塞案例进行回顾性分析。结果肺动脉栓塞致死以男性多见;发病年龄主要集中在31～70岁之间;主要诱因是严重外伤、长期卧床后运动,以下肢静脉系统血栓形成并脱落致肺动脉栓塞最为常见。结论对肺动脉栓塞致死案例法医病理学鉴定要点进行了总结。     

A sudden death with lung embolism after inadvertent infusion of zinc oxide shake lotion

A 74-year old woman in postoperative treatment after a colonic surgery died immediately after perfusion of about 1.5 mL of a white emulsion which was believed to contain 1% propofol via cardiac catheter into the right atrium. It was strongly suspected that a syringe with a zinc oxide shake lotion (consisting of 20% ZnO, 20% talc, 25% glycerol and 35% water) which was intended for external treatment had been mistaken for the propofol syringe. During autopsy, an anatomic cause of death could not be found. In order to exclude an intoxication and to determine the significance of the perfusion fluid in this context, toxicological and histological investigations were performed. Propofol and other drugs applied to the patient were found in therapeutic or sub-therapeutic range. However, in comparison to a control case, the zinc concentrations determined by AAS were about 200 times higher in lung tissue, 10 times higher in heart blood and 3–4 times higher in kidney and liver tissue. No increase was seen in venous blood. Histology showed a strong embolism of the lung tissue with birefingent sharp-edged crystals, which were identified as the talcum, and an amorphous component (ZnO). The same embolism was seen to a medium extent also in the brain sections and to a low extent in heart, liver, pancreas and kidney. Pulmonary embolism by talcum and zinc oxide was established as the cause of death which occurred by syringe swap due to insufficient security precautions in the drug administration. The results are discussed in context of pulmonary microembolism cases frequently described for drug addicts after injection of crashed talcum containing tablets.     

Fatal Venous Air Embolism Following Intravenous Infusion*

Abstract: Venous air embolism has been reported as a complication of invasive diagnostic and therapeutic procedures or accidental trauma. Little is known about the incidence of air embolism after minimal intravenous manipulations such as the insertion of a peripheral intravenous cannula. Only when large amounts of air sufficient enough to block the cardiovascular system enter, the patient develops symptoms and signs of severe neurological injury, cardiovascular collapse, or death. The dead body of a 14‐year‐old boy was brought for postmortem examination with allegations of death from negligence during treatment. He was treated for pain in the abdomen in a hospital by attendants in telephonic consultation with a medical practitioner. Following intravenous infusions, the boy died suddenly in respiratory distress. Gross findings indicated the death to be from venous air embolism. Chemical analysis, histopathology, and microbiology ruled out other causes of death. Dilemmas of the case with difficulties in diagnosis are being presented herewith.     

20例脂肪栓塞死亡的法医学分析

目的分析脂肪栓塞综合征（fatembolismsyndrome,FES）死亡的一般情况以及法医病理学特点,为此类案件的法医病理学鉴定提供参考。方法选取某大学法医学鉴定中心1999—2012年20例FES死亡案件．对其一般情况及法医病理学特点（包括致伤方式、损伤类型、临床表现、病理学改变等方面）进行总结。结果脂肪栓塞主要见于损伤导致的长骨骨折和全身大面积软组织损伤,主要类型为肺脂肪栓塞,偶见合并脑脂肪栓塞。症状多出现在伤后和术后较短时间内,组织病理学检查可在肺小血管内检见大量脂滴并经特殊染色证实。结论FES死亡案例在损伤类型、脂肪栓塞出现症状时间及组织病理学表现等方面均有一定规律和特点。在鉴定中应注意进行特殊染色（油红0染色）处理,寻找FES的直接证据。     

The potential of venous air embolism ascending retrograde to the brain

A bench study was performed to investigate the potential of air bubbles entering a central vein via a central venous catheter to ascend retrograde to the brain. The results support the hypothesis that air bubbles may rise retrograde against the venous blood flow, depending on bubble size, central vein diameter and cardiac output. A review of radiological findings in published case reports indicates that the occurrence of retrograde cerebral air embolism is underestimated.     

Fatal paradoxical air embolism diagnosed by postmortem imaging and autopsy

The recognition and visualization of an arterial gas embolism are difficult. We report a case of sudden death caused by paradoxical air embolism of coronary and cerebral arteries, diagnosed by the pre autopsy computed tomography (CT) scanning. A 54-year-old woman suddenly died after the self-removal of the jugular vein catheter. Postmortem imaging examination using CT scanning showed multiple gas embolisms in the cerebral arteries, pulmonary artery, right atrium and ventricle, left ventricle, aorta, and coronary arteries. These findings suggested that the occurrence of acute ischemia of the brain and heart caused by massive air inflow to the artery. Conventional autopsy revealed a patent foramen ovale of the heart. These results indicated that the patient died of paradoxical air embolization of the coronary and cerebral arteries through a patent foramen ovale because of right-to-left shunting. The use of postmortem imaging as an aid for conventional autopsy has proved to be of advantage in the case of gas embolism.     

Saddle Pulmonary Embolism with Paradoxical Coronary Artery Embolism through a Patent Foramen Ovale

A 35‐year‐old male patient was found in cardiac arrest in his vehicle, with no apparent injuries after a minor motor vehicle collision. The decedent was found to have a saddle pulmonary embolus with a thromboembolus impacted across a patent foramen ovale and a paradoxical embolism in the circumflex coronary artery, as well as significant clotting in the deep veins of both lower extremities. There were no risk factors in his history to explain the deep venous thrombosis; family history suggested the possibility of an unrecognized clotting disorder.     

Suture Embolism of the Left Superior Lobar Pulmonary Artery

Endogenous pulmonary thromboemboli are a common cause of noncardiac sudden natural death. Embolism of exogenous material is a rare but potential finding in autopsies following surgeries, medical procedures, penetrating trauma, and nonparenteral drug abuse. This report describes the first case of a suture embolism of the left superior lobar pulmonary artery following complicated abdominal surgery.     

Suicide by Intentional Air embolism

Venous air embolism occurs when air enters the venous system. The main causes of venous air embolism include medical procedures, neck and head trauma, and injuries of the genitals. Self‐induced suicidal (and intentional) air embolism is extremely rare. The authors report a rare case of a suicidal air embolism committed using a self‐made tool composed of a plastic bottle and an infusion set, injecting nearly 2000 mL of air into the cubital vein. The toxicological analysis suggested that midazolam, together with air, was also injected into the circulation using the same bottle and infusion set.     

Infant death due to air embolism from peripheral venous infusion

An otherwise healthy male infant was brought to the hospital because the mother suspected superficial infection at the operative site 5 days after an inguinal hernia repair. He was admitted to the pediatric unit overnight to be evaluated by his surgeon the next morning. When a venous infusion of maintenance fluids was started, the patient immediately went into cardio-respiratory arrest and was pronounced dead after resuscitation efforts failed. Subsequently, air collections were found in both venous and arterial circulations, including the splenoportal system. Detailed review of the clinical presentation and course, laboratory results, radiological, and pathological findings, along with a review of pertinent literature provides an explanation for the death by air embolism. Apparent inconsistent findings both radiographically and at autopsy are resolved. The mechanism of distribution of air to both systemic and splenoportal circulation is discussed. We believe this to be only the eighth case reported in English-language literature of infantile death from peripheral venous infusion. In all age groups, we find only six other cases in the English-language literature of gas found concomitantly in both the systemic and portal venous systems.     

α-纤维蛋白原基因多态性与肺动脉栓塞相关性初探

目的探讨α-纤维蛋白原Thr312Ala基因的多态性分布与肺动脉栓塞的相关性。方法选取尸检已确诊的肺动脉栓塞病例的甲醛固定心肌组织14例和正常健康人群外周血56例,采用改良酚-氯仿法和Chelex100法分别提取心肌组织和外周静脉血基因组DNA,用PCR-RFLP法检测α-纤维蛋白原基因Thr312Ala多态性,并分析其与肺动脉栓塞的关联性。结果α-纤维蛋白原Thr312Ala基因的各基因型在肺动脉栓塞组与对照组比较差异具有显著性意义（P〈0.05）;各等位基因在两组间比较差异具有显著性意义（P〈0.05）;A等位基因与PE呈负相关（RR=0.475,P〈0.05）;G等位基因与PE呈正相关（RR=5.818,P〈0.05）。结论α-纤维蛋白原基因Thr312Ala位点G等位基因与肺动脉栓塞有正关联,肺动脉栓塞死亡者中GA、GG基因型分布频率较高,本文数据可为相关研究提供参考。     

Activated protein C resistance is uncommon in sudden death due to pulmonary embolism

Activated protein C resistance (APC-R) is the most common inherited defect of the coagulation system known to date, affecting 3-5% of Americans. It is an autosomal dominant disorder associated with an increased risk of venous thrombosis and is reportedly found in 21% of individuals with deep venous thrombosis. Medical examiners are in a unique position to make the diagnosis since a fatal pulmonary embolism may be the first manifestation of the disorder. This study examines the prevalence of APC-R in individuals who die suddenly of pulmonary embolism to help medical examiners decide if routine testing is indicated. We examined 66 cases of sudden death due to pulmonary embolism seen at the Bexar County Forensic Science Center in San Antonio, Texas, from 1993-1997. The median age was 46 years with a range of 14 to 93 years. Fifty-three percent were Caucasian, 24% were African-American, and 23% were Hispanic. Twenty-seven percent had no known risk factors for pulmonary embolism. Whole blood was tested for the factor V codon 506Q mutation responsible for APC-R using polymerase chain reaction. The prevalence of APC-R was 4.5%, which is similar to the prevalence of APC-R in the general American population. These data imply that individuals with APC-R are not in increased risk for sudden death due to pulmonary embolism, or, conversely, that most fatal pulmonary emboli seen in the medical examiner setting are not induced by APC-R. Routine postmortem testing for the factor V 506Q mutation does not appear indicated at this time, given the low prevalence and high cost of testing.     

An autopsy case of intraoperative death due to pulmonary fat embolism—possibly caused by release of tourniquet after multiple muscle-release and tenotomy of the bilateral lower limbs

We report a case of a juvenile male with muscle rigidity caused by cerebral palsy who experienced intraoperative sudden death due to pulmonary fat embolism after multiple muscle-release and tenotomy of the bilateral lower limbs. Data were obtained through review of the surgical and anesthesia records, as well as from autopsy and histopathological examination. All surgical procedures were performed within the same operation, beginning with the right lower limb and then proceeding with the left lower limb, with application of a pneumatic tourniquet to avoid intraoperative hemorrhage. Slight changes in the hemodynamics were noticed after release of the right tourniquet. Further, sudden onset of hypotension, severe bradycardia, and a marked decrease in percutaneously monitored oxygen saturation occurred just after release of the left tourniquet when the left limb was raised for casting. The patient died despite immediate and vigorous cardiopulmonary resuscitation. At autopsy performed 20 h after death, examination of the lungs revealed a pale surface, slight edema, and obvious fat droplets in the vessels at the cut surfaces. Histopathological examination with fat staining was notable for the presence of pulmonary fat embolism. These results suggest that restoration of venous return after removal of the tourniquet combined with massive fat embolism from dead spaces was the likely cause of death.     

Pulmonary embolism: a rare cause of sudden infant death

Pulmonary embolism can be observed at any age, but it occurs very rarely in the infant. The authors report the case of a 12-month-old boy who suddenly died during clinical improvement of gastroenteritis associated with otitis. Autopsy showed signs of dehydration and acute left pulmonary embolism, which was the cause of death. Thrombosis of the inferior vena cava extending into renal veins was seen. In this case, plasma hyperosmolality caused by dehydration might have favored the formation of venous thromboses. The various risk factors of pulmonary embolism in the child are discussed, including genetic factors.     

Large droplet lipids in blood in the right ventricle

In several cases of fatal blunt-trauma injuries or after exposure to severe burning, large-drop fatty substances, discernible to the naked eye, were found in the venous blood of the right ventricle. Thin-layer chromatographic separation of the extracted lipids demonstrated an increase in the triglyceride fraction. Analysis of the fatty acids by means of combined gas chromatography/mass spectrometry showed a shift towards oleic acid. The distribution pattern of the molecular weights was determined by means of DCI-mass spectrometry in order to characterize the triglycerides in detail. The total chemical findings indicated that the visible lipids present in the right ventricle had predominantly derived from the adipose tissues. In cases of post mortem burning (without vital traumata) no typical pulmonary fat embolism had developed despite massive lipemia in the venous blood.     

Fatal iatrogenic BaSO4 embolism: morphological and ultrastructural findings confirmed by X-ray microanalysis and ICP-AES

A 42-year-old woman died from massive barium sulfate (BaSO(4)) lung embolism after a balloon catheter intended for elective colonography was inserted into her vagina. The vaginal insertion of the balloon catheter caused a bilateral laceration of the vaginal wall which was followed by penetration of BaSO(4) into the afferent veins and massive pulmonary embolism. Fluoroscopy performed during the fatal events and post-mortem X-rays revealed a radio-opaque substance in the vagina and uterus, the pelvic vessels and the vena cava, the right heart chambers, the lungs, and the kidneys. In addition to lungs, finely granular intravascular particles were demonstrated histologically in several organs including the brain and the glomerular capillaries. Scanning (SEM) and transmission (TEM) electron microscopy together with X-ray microanalysis, and inductively coupled plasma atomic emission spectrometry (ICP-AES) allowed the definite identification of BaSO(4) in lungs and confirmed its capacity to penetrate the pulmonary filter and to embolise via the systemic circulation in various organs.     

脂肪栓塞中苏丹Ⅲ染色的定量分析

目的探讨苏丹Ⅲ染色如何定量应用于脂肪栓塞的法医学鉴定。方法应用苏丹Ⅲ对11例肺脂肪栓塞猝死的案例和11例其他原因致死的案例进行染色,并结合统计学方法对脂肪栓塞的阳性面积百分率及脂肪栓子数进行定量分析。结果脂肪栓塞致死者肺内苏丹Ⅲ染色阳性面积百分率为（5±1．7）％、脂肪栓子数为（9±2．4）％,均远大于其他原因致死的案例（P〈0．01）。结论苏丹Ⅲ染色法定量分析在脂肪栓塞中的法医学鉴定上结果可靠。     

新型毒品5-甲氧基-α-甲基色胺油状物的GC-MS定性检验

目的通过分析未知检材样本提取后的质谱碎裂峰,建立了5-甲氧基-α-甲基色胺(5-MeO-AMT)的气相色谱-质谱(GC-MS)定性分析方法,并阐述其在EI离子源轰击下的分子裂解机制。方法未知样品油状物用氢氧化钠溶液溶解后加入适量乙酸乙酯,充分振荡后吸取上清液采用气相色谱-质谱(GC-MS)检测。结果测得未知组分(RT=12.754min)的质谱特征碎片峰(m/z)信息为161.1(基峰)、204.2、146.1、130.1、117.1和89.0。经与NIST谱库和DEA报告质谱图比对,确定为5-MeO-AMT;通过查阅文献资料,对上述质谱特征碎片峰的产生机制进行了推断。结论该方法操作简单、结论可靠,可用于5-MeO-AMT的检验。