Pathophysiological effect of fat embolism in a canine model of pulmonary contusion.

BACKGROUND: The objective of this study was to determine the individual and combined effects of pulmonary contusion and fat embolism on the hemodynamics and pulmonary pathophysiology in a canine model of acute traumatic pulmonary injury. METHODS: After a thoracotomy, twenty-one skeletally mature dogs were randomly assigned to one of three groups. Unilateral pulmonary contusion alone was produced in Group 1 (seven dogs); pulmonary contusion and fat embolism, in Group 2 (seven dogs); and fat embolism alone, in Group 3 (seven dogs). Pulmonary contusion was produced by standardized compression of the left lung with a piezoelectric force transducer. Fat embolism was produced by femoral and tibial reaming followed by pressurization of the intramedullary canals. Cardiac output, systolic blood pressure, peak airway pressure, pulmonary arterial pressure, pulmonary capillary wedge pressure, partial pressure of arterial oxygen, and partial pressure of carbon dioxide were monitored for all groups. From these data, several outcome parameters were calculated: total thoracic compliance, alveolar-arterial oxygen gradient, and ratio of partial pressure of arterial oxygen to fractional inspired oxygen concentration. All of the dogs were killed after eight hours, and tissue samples were obtained from the brain, kidneys, and lungs for histological analysis. Lung samples were assigned scores for pulmonary edema (the presence of fluid in the alveoli) and inflammation (the presence of neutrophils or hyaline membranes, or both). The percentage of the total area occupied by fat was determined. RESULTS: Pulmonary contusion alone caused a significant increase in the alveolar-arterial oxygen gradient but only after seven hours (p = 0.034). Fat embolism alone caused a significant transient decrease in systolic blood pressure (p = 0.001) and a significant transient increase in pulmonary arterial pressure (p = 0.01) and pulmonary capillary wedge pressure (p = 0.015). Fat embolism alone also caused a significant sustained decrease in the ratio of partial pressure of arterial oxygen to fractional inspired oxygen concentration (p = 0.0001) and a significant increase in the alveolar-arterial oxygen gradient (p = 0.0001). The combination of pulmonary contusion and fat embolism caused a significant transient increase in pulmonary capillary wedge pressure (p = 0.0013) as well as a significant sustained decrease in partial pressure of arterial oxygen (p = 0.0001) and a significant decrease in systolic blood pressure (p = 0.001) that lasted for an hour. Pulmonary contusion followed by fat embolism caused a significant increase in peak airway pressure (p = 0.015), alveolar-arterial oxygen gradient (p = 0.0001), and pulmonary arterial pressure (p = 0.01), and these effects persisted for five hours. Total thoracic compliance was decreased 6.4 percent by pulmonary contusion alone, 4.6 percent by fat embolism alone, and 23.5 percent by pulmonary contusion followed by fat embolism. The ratio of partial pressure of arterial oxygen to fractional inspired oxygen concentration was decreased 23.7 percent by pulmonary contusion alone, 52.3 percent by fat embolism alone, and 65.8 percent by pulmonary contusion followed by fat embolism. The mean pulmonary edema score was significantly higher with the combined injury than with either injury alone (p = 0.0001). None of the samples from the lungs demonstrated inflammation. Fat embolism combined with pulmonary contusion resulted in a significantly greater mean percentage of the area occupied by fat in the noncontused right lung than in the contused left lung (p = 0.001); however, no significant difference between the right and left lungs could be detected with fat embolism alone. The mean percentage of the glomerular and cerebral areas occupied by fat was greater with fat embolism combined with pulmonary contusion than with fat embolism alone (p = 0.0001 and p = 0.01, respectively). (ABSTRACT TRUNCATED)     

脂肪栓塞综合征的早期诊断与治疗

目的：探讨脂肪栓塞综合征早期诊断的意义和方法。方法：采用连续检查动脉血氧分压下降情况，早期诊断，并使用吸氧、地塞米松、丹参注射液和桑白皮汤加减，治疗33例脂肪栓塞综合征。结果：33例中32例抢救成功。结论：早期诊断，及时处理，是救治脂肪栓塞综合征成功的关键。     

Possible venous air embolism during open eye surgery in a child

PURPOSE: Although venous air embolism is a well recognized complication within most surgical subspecialties, it has only been reported recently during eye surgery in one adult, and never before in a child. We describe the case of a 17-month-old boy who sustained a possible air embolism during repair of an open trauma of his right eye. CLINICAL FEATURES: A vitrectomy through the pars plana with air-fluid exchange of the posterior chamber was performed under general anesthesia to remove a foreign body which had impaled the optic nerve. A few minutes after removal of the foreign body, a notable decrease in end-tidal CO(2), oxygen saturation and arterial blood pressure occurred, requiring administration of a high inspired oxygen fraction and vasopressors. Venous air embolism was strongly suspected after other causes of a decrease of end-tidal CO(2) and hypoxemia had been excluded. An arterial blood gas confirmed hypoxemia and respiratory acidosis. CONCLUSION: Although venous air embolism is a rare complication of eye surgery, it should nevertheless be considered as a possible complication during air-fluid exchange vitrectomy in children.     

Iatrogenic gas embolism following surgical lavage of a wound with hydrogen peroxide

The use of hydrogen peroxide (H2O2) in surgery for its antiseptic properties has been associated with life-threatening complications. We report a case of severe oxygen embolism after wound irrigation with H2O2 in a 17-year-old boy undergoing surgical dressing of a large thigh trauma under general anaesthesia. During muscle lavage with 400 mL of H2O2 3%, severe shock suddenly occurred. On the basis of clinical presentation, the diagnosis of pulmonary gas embolism was strongly suspected. Symptomatic treatment initiated immediately, restaured a normal haemodynamic state within a few minutes and the patient recovered without sequelae. The degradation of H2O2 results in considerable amounts of gaseous oxygen. One mL of H2O2 can produce in the tissues 10 mL of oxygen. This gas can enter the circulation and determine severe embolism. The treatment should be initiated without delay. The administration of H2O2 under pressure is contraindicated during surgery.     

Systemic air embolism in a fungal pneumonia patient with lung cavities formationand review of literature

Systemic air embolism is a rare but potentially fatal complication related to many factors. The purpose of this article is to alert clinicians once patients occurs an abnormal neurological and cardiovascular status, following minor traumatic treatment, air embolism should be considered. A 20-year-old man who presented with fungal pneumonia with lung cavities formation was admitted to an intensive care unit (ICU) and received positive airway pressure ventilation. Four days later, the fungal pneumonia was improved, but the patient''s blood pressure and arterial oxygen saturation deteriorated, so computed tomography (CT) scans were preformed to reevaluate him. The scans detected air embolism in the left atrium and ventricle, ascending aorta, aortic arch and its branches (right brachiocephalic, bilateral common carotid and right subclavian arteries), descending aorta and right coronary artery. A CT scan of the abdomen revealed air in the spleen, cauda pancreatic, superior mesenteric artery and right external iliac artery. The patient died two days later from multiple organ dysfunction. We suggest that vascular air embolism should be considered under mechanical ventilation when patients'' neurologic and cardio vascular status deteriorates, and hyperbaric oxygen therapy should be conducted immediately.     

Arterial gas embolism: a review of cases at Prince of Wales Hospital, Sydney, 1996 to 2006

Arterial gas embolism may occur as a complication of diving or certain medical procedures. Although relatively rare, the consequences may be disastrous. Recent articles in the critical care literature suggest the non-hyperbaric medical community may not be aware of the role for hyperbaric oxygen therapy in non-diving related gas embolism. This review is part of an Australian appraisal of experience in the management of arterial gas embolism over the last 10 years. We identified all patients referred to Prince of Wales Hospital Department of Diving and Hyperbaric Medicine with a diagnosis of arterial gas embolism from 1996 to 2006. Twenty-six patient records met our selection criteria, eight iatrogenic and 18 diving related. All patients were treated initially with a 280 kPa compression schedule. At discharge six patients were left with residual symptoms. Four were left with minor symptoms that did not significantly impact quality of life. Two remained severely affected with major neurological injury. Both had non-diving-related arterial gas embolism. There was a good outcome in the majority of patients who presented with arterial gas embolism and were treated with compression.     

Oxygen venous embolism after the use of hydrogen peroxide during lumbar discectomy

Purpose

The knee-prone position is commonly used for patients undergoing spinal surgery. Venous air embolism m such a position may be produced by the negative venous pressure gradient between the ambient air and the venous plexuses of the spinous process. When hydrogen peroxide is used to deanse the wound, oxygen is produced. We report a case of suspected oxygen venous embolism during lumbar discectomy in the knee-prone position after use of H₂O₂.

Clinical Features

Immediately after irngation of a discectomy wound with H₂O₂. a dramatic decrease of the P_ETCO₂, blood pressure and oxygen saturation coincident with ST segment elevation occurred suggesting a coronary gas embolism. Symptomatic treatment was initiated immediately and the patient recovered without any sequelae.

Conclusion

Although hydrogen peroxide has an innocuous reputation, cases of accidental ingestion or massive gas embolism after wound irngation leading to death have been reported. A review of the literature suggests that many of the clinical and physiopathological features of air and oxygen emboli are similar. For both, measures of prevention and treatment of complications are similar. We argue that the use of hydrogen peroxide should be avoided during procedures where the position of the patient (sitting, knee-prone) increases the risk of gas embolism and that hydrogen peroxide is a potentially dangerous solution.     

Physiologic emboli changes observed during total hip replacement arthroplasty. A clinical prospective study.

Fat embolism does occur with introduction of femoral components during total hip replacement arthroplasty. If massive, abrupt severe irreversible interruption of pulmonary oxygen exchange or profusion can occur. Adequate intramedullary femoral canal venting can significantly reduce the amount or dosage of fat embolism and thereby reduce and prevent primary or superimposing secondary injury of the capillary-alveolar gas exchange area within the lungs. The occurrence of fat embolism supports the mechanical theory. It also demonstrates that a patient surviving the effects of the acute mechanical pulmonary insult may still have to survive the more common and typical clinical picture of the metabolic pulmonary disease result of fat embolism that likewise can be irreversible. To prevent the occurrence of fat embolism during femoral component insertion with total hip replacement arthroplasty, the following techniques are imperative: (1) adequate femoral intramedullary canal venting; (2) maintenance of pulmonary arterial oxygen tension; (3) maintenance of blood volume.     

Oxygen embolism after hydrogen peroxide irrigation of a vulvar abscess

We report a case of venous oxygen embolism in a 33-yr-old healthywoman after irrigation of a vulvar abscess with 25 ml of 3%hydrogen peroxide. Venous oxygen embolism was diagnosed by thedevelopment of sudden hypoxia associated with a decrease inend-tidal carbon dioxide concentration from 5.3 kPa to 3.2 kPa,and a ‘mill-wheel’ sound on cardiac auscultationsoon after injection of the solution. The patient respondedto corrective treatment including the Trendelenburg positionand 100% oxygen. She made an uneventful recovery. We discussthe possible causative mechanism of this embolism, the differentdiagnostic methods, and the controversial aspects of availabletreatments. We emphasize that hydrogen peroxide is a dangerousand unsuitable agent for routine wound irrigation and debridement. Br J Anaesth 2002; 88: 597–9     

原发性肝癌经导管肝动脉化疗栓塞术后肺栓塞4例临床分析

目的分析原发性肝癌经导管肝动脉化疗栓塞（TACE）术后并发肺栓塞的临床特点，探讨发生机制、早期诊断和治疗方法。方法2000年1月至2007年12月，在我院接受TACE的原发性肝癌患者31869人次，其中术后出现肺栓塞患者4例。回顾性分析该4例患者的临床特点及发病机制、诊断、治疗方式。结果TACE术后并发肺栓塞例数占同期我院TACE例数的0．02％；出现肺栓塞时间为术后0．5h～5d，患者表现为呼吸困难、紫绀、心悸、胸痛、黄疸、血尿及血PO2、SatO2下降等肺栓塞症状；本组死亡2例，死亡率50％。结论肺栓塞是原发性肝癌患者TACE术后的严重并发症，是碘油阻塞为主的多种栓塞因素共同作用的结果。本病起病急骤，死亡率高。肺动脉造影及D—Dimer是早期明确诊断的重要方法。     

骨折并发脑脂肪栓塞的临床诊治研究

目的　探讨骨折后并发脑脂肪栓塞的发病机理、诊断及治疗措施。方法　回顾性分析 1 6例骨折后并发的以意识障碍、偏瘫及皮肤出血点为主要症状的脑型脂肪栓塞综合征 (FES)。该组均采取以激素和高压氧为主的综合治疗。结果　 1 6例中 1 5例于 3～ 1 5d内清醒 ,神经功能缺失症状于 1 5～ 35d内恢复 ;1例呈植物生存状态。结论　脑脂肪栓塞为排他诊断 ,应以临床诊断为主 ,明确诊断后及早行以激素和高压氧为主的综合治疗 ,疗效明显 ,治愈率高     

Fat emboli in bilateral total knee arthroplasty. Predictive factors for neurologic manifestations

Fat embolism after bilateral total knee arthroplasty (TKA) occurred in 12% of the authors' patients having bilateral TKA with intramedullary instrumentation. Usually embolism was manifested as neurologic changes, most often changes of mental status. Death is a potential consequence, and this occurred in one patient. The present authors believe that fat embolism is not predictable preoperatively and propose that intraoperative guidelines can be used to reduce risk of this complication. Intraoperative monitoring by a Swan-Ganz catheter will permit measurement of the pulmonary arterial pressure, pulmonary vascular resistance, and pulmonary capillary wedge pressure. A sustained rise of any of these would be an indication to abort the second knee operation. If Swan-Ganz catheter is not available, a sustained fall of oxygen saturation to 90% or lower can be used as a criterion. The risk for fat embolism is increased with the use of intramedullary instrumentation, and the above guidelines are recommended for operations with this type of instrumentation. A fluted intramedullary rod and vent holes should be used.     

Venous oxygen embolism due to hydrogen peroxide irrigation during posterior fossa surgery

Hazards of application of hydrogen peroxide to semiclosed space are well known. We present a case of suspected gas embolism following hydrogen peroxide irrigation of the surgical field during posterior fossa surgery in the prone position. Severe cardiovascular collapse occurred when the wound was irrigated with hydrogen peroxide solution. Generation of pressure gradient leads to absorption of a considerable amount of oxygen giving rise to features of venous gas embolism. Although the case was associated with an uneventful recovery, use of hydrogen peroxide for securing hemostasis should be avoided.     

Gas embolism during laparoscopic cholecystectomy

Advancements in laparoscopic surgery have resulted in decreased length of hospitalization, reduced postoperative pain, and better cosmesis following general surgical procedures. Carbon dioxide gas embolism is a rare occurrence that can be fatal. We report the case of a patient with a venous gas embolism during laparoscopic cholecystectomy. A 63-year-old woman presented with intermittent right upper quadrant pain, and her abdominal ultrasound showed a possible gallbladder polyp. A laparoscopic cholecystectomy was planned. A Veress needle was placed in the right upper quadrant to initiate abdominal access. Shortly after carbon dioxide insufflation, the patient's hemodynamic status deteriorated, her oxygen saturation dropped, and her end-tidal CO2 decreased. Gas insufflation was immediately stopped, and the patient was resuscitated. She stabilized quickly, and the procedure was performed without further event. She did well postoperatively and was discharged home the next day. Carbon dioxide embolism during laparoscopy, albeit rare, can be a fatal complication of the procedure. Whenever sudden changes in hemodynamic stability occur, venous gas embolism should be considered. As laparoscopic techniques and applications are expanded, the general surgeon must be aware of this entity.     

Possible air embolism during eye surgery

We report a case of possible air embolism during a three-port pars plana vitrectomy and air-fluid exchange of the vitreous cavity of the eye. After the start of intraocular air flushing, sudden tachycardia, a decrease in oxygen saturation and end-tidal carbon dioxide tension, and a distinct "mill-wheel" murmur were observed. Venous air embolism was suspected but other sources of air entry into the circulation and a thromboembolic event were excluded. Once intraocular air flushing was ceased, clinical variables returned to normal within minutes. In conclusion, during air-fluid exchange of the vitreous cavity, air embolism should be considered as a possible rare complication.     

Probable gas embolism during operative hysteroscopy caused by products of combustion

PURPOSE: Gas embolism is a rare but well documented entity during operative hysteroscopy, with an incidence of 10-50%. Catastrophic outcomes occur at a rate of three in 17,000 procedures. The purpose of this report is to present a non-fatal case of gas embolism probably caused by the gaseous products of combustion. CLINICAL FEATURES: A 50-yr-old woman with a history of menorrhagia was scheduled for hysteroscopy and endometrial ablation and polypectomy. Fifteen minutes into the procedure, with the patient in lithotomy position, 20 degree head down tilt, and breathing spontaneously, a sudden oxygen desaturation occurred from 97% to 87%. The patient's end-tidal carbon dioxide dropped from 46 mmHg to 27 mmHg. The patient's breathing pattern remained normal, respiratory rate remained 11-12 breaths x min(-1) but amplitude of the reservoir bag movement was increased. Cardiovascular variables remained stable. She responded rapidly to 100% oxygen and made an uneventful recovery. Having ruled out other possible causes, we concluded gas embolism was responsible for the fall in oxygen saturation and end-tidal CO(2). CONCLUSION: With all the precautions in place to minimize the likelihood of fluid overload and ambient air embolism occurring, we surmised that products of combustion were the cause of the gas embolism. During endometrial ablation, gaseous products of combustion, mainly carbon dioxide, accumulate. The gases may then contribute to the rise in uterine pressure that occurs as irrigation fluid enters the uterus and this rise in pressure in turn encourages passage of gas into the open venous sinuses.     

Transcutaneous O2 and CO2 monitoring of neurosurgical patients: detection of air embolism

Transcutaneous oxygen tension (PtcO2) and transcutaneous carbon dioxide tension (PtcCO2) were monitored in 60 patients undergoing neurosurgical procedures. Twenty-six patients were in the sitting position and underwent routine monitoring for air embolism. Seventeen episodes of air embolism were diagnosed by precordial Doppler ultrasound or transesophageal echocardiography, and the PtcO2 decreased early during the course of each episode. The mean PtcO2 decrease was 48 +/- 35 mmHg. During ten episodes the end-tidal carbon dioxide tension (PETCO2) decreased but only after the PtcO2 had already begun to decrease. PtcCO2 increased during air embolism but PETCO2 changes preceded the change in PtcCO2 by 1-2 min. Transcutaneous values during air embolism were verified with simultaneous arterial blood gas values during six air embolism episodes. A strong positive correlation was found between transcutaneous and arterial oxygen and carbon dioxide tensions. Correcting the PtcCO2 by the patient's baseline PtcCO2/PaCO2 ratio, PtcCO2 monitoring correctly reflected hypocarbia, normocarbia, and hypercarbia in 92% of the cases. PtcO2 monitoring was useful in detecting venous air embolism and may respond sooner than PETCO2. PtcCO2 monitoring was not useful as an early detector of air embolism.     

Thoracoabdominal CT scan: a useful tool for the diagnosis of air embolism during an endoscopic retrograde cholangiopancreatography

We report the case of an 82-year-old woman treated with biliary stents for an ampulloma of Vater's papilla, with recurrent stenosis of the common bile duct. She was hospitalized with a cholestasis. An endoscopic retrograde cholangiopancreatography (ERCP) was scheduled to change the biliary stent for a metallic one, under general anaesthesia, with oral intubation. The ERCP was performed initially without any complication, but as the metallic biliary stent was placed, an air embolism occurred and a cardiac arrest happened immediately. The etiologic diagnosis was quickly confirmed by an injected multislice body-scan, which showed liver, right heart and brain gas embolism. Cardiopulmonary resuscitation allowed a complete haemodynamic recovery but a poor neurological recovery. The patient was transferred in intensive care unit, were she died 12 days after, despite hyperbaric oxygen therapy and the disappearance of the air embolism on the following computed tomography scan. This case may be useful to recall the utility of a body-scan for the diagnosis, treatment and follow-up of an air embolism during ERCP.     

The fat embolism syndrome, results of a therapeutic regime.

Results of a therapeutic regime for the fat embolism syndrome are presented. The basis of this regime is to prevent hypoxia by use of oxygen and if necessary intermittent positive pressure ventilation. Prophylactic oxygen therapy in patients likely to develop the fat embolism syndorme is suggested.     

Cerebral air embolism resulting from invasive medical procedures. Treatment with hyperbaric oxygen.

The introduction of air into the venous or arterial circulation can cause cerebral air embolism, leading to severe neurological deficit or death. Air injected into the arterial circulation may have direct access to the cerebral circulation. A patent foramen ovale provides a right-to-left shunt for venous air to embolize to the cerebral arteries. The ability of the pulmonary vasculature to filter air may be exceeded by bolus injections of large amounts of air. Sixteen patients underwent hyperbaric oxygen therapy for cerebral air embolism. Neurological symptoms included focal motor deficit, changes in sensorium, and visual and sensory deficits. Eight patients (50%) had complete relief of symptoms as a result of hyperbaric treatment, five (31%) had partial relief, and three patients (19%) had no benefit, two of whom died. The treatment of cerebral air embolism with hyperbaric oxygen is based upon mechanical compression of air bubbles to a much smaller size and the delivery of high doses of oxygen to ischemic brain tissue.