Case Discussion      A 19-years-old man was well until Oct. 6, 2000 when he suffered from a traffic accident. He was sent to a local hospital where a compound fracture of right femoral bone and multiple abrasion wounds over bilateral lower limbs were found. There was no evidence of chest or head contusion. The initial chest radiograph was normal (Figure 1). He underwent ORIF (open reduction and internal fixation) on the next day. The surgical procedure was smooth, without the need for blood transfusion. Unfortunately, chills and high fever developed after operation. Progressive dyspnea and mild drowsiness were noted one day after the operation. The chest roentgenography revealed multiple patchy lesions over bilateral lung fields (Figure 2). The blood gases revealed severe hypoxemia. With the suspicion of fat embolism, he was transferred to the ICU of a teaching hospital for further management on Oct. 9.      On examination, his consciousness was clear. The blood pressure was 162/97 mm Hg and pulse rate was 102 per minute. He was in sever respiratory distress with a respiratory rate of 32 per minute. The oxygen saturation was around 93% when breathing through a non-rebreathing mask. The breathing sounds were coarse, without wheezing or crackles. There were no heart murmurs. There was no evidence of local inflammation over the surgical wound. No ecchymosis or petechiae were found on his upper trunk and extremities. Other physical and neurological examinations were unremarkable. He was intubated and the arterial oxygenation was maintained by pressure-controlled ventilation and high positive end-expiratory pressure with intermittent prone positioning. The chest computed tomography revealed diffuse multiple lung consolidation and small amount of pleural effusion over bilateral depending part (Figure 3). The bronchoalveolar lavage (BAL) performed on the 3rd hospital day yielded bloody fluid and cytological examinations revealed many intra-macrophageal fat droplets under Sudan III staining (Figure 4). Microscopic examinations of open lung biopsy revealed numerous fat globules were found in the arterioles (Figure 5). All cultures of clinical specimens, including blood, urine, suction sputum, pleural effusion, BAL fluid and lung tissue, did not grow any pathogens., His general condition improved gradually under supportive care and PaO2 rose to 90 mm Hg (FiO2 40%) on the 7th hospital day. He was extubated smoothly on the 9th hospital day. Laboratory results were as following. 1. CBC/DC:   Hb Hct MCV PLT WBC Seg. Eos. Bas. Mono. Lym.   g/dL % fL K/uL K/uL % % % % % 10/9 10.3 30.3 87.6 105.0 5.16 84.1 1.9 0.8 6.0 7.2 10/11 10.0 29.7 90.3 108.0 5.69 71.6 6.9 0.7 8.1 12.7 10/13 11.5 33.7 89.9 167.0 7.9 69.7 4.1 0.4 9.7 16.1 2. ABG:    PH  PaCO2 PaO2 HCO3 BE Ventilator FiO2     MmHg mmHg mEq/l mEq/l     10/8 7.4 30 24       Room air 10/9 7.42 33.9 63.8 21.5 -2.0   Non-rebreath. 10/11 7.39 39.8 59.2 23.7 -0.6 CMV 50% 10/14 7.44 39.9 76.7 26.5 2.7 PCV 35% 10/15 7.44 35.9 90.4 24.0 0.5 PCV 30% 3.Biochemistry and electrolyte:   BUN Creat. Na K Ca Cl P Mg   mg/dl mg/dl mmole/l mmole/l mmole/l mmole/l mg/dl mmole/l 10/9 13.0 0.9 140.0 3.6 1.81 109.0 1.6 0.72 10/10 14.0 0.8 140.0 3.7 1.76 106.0 2.0 1.0 10/12 17.0 0.9 142.0 3.7         10/14 17.0 0.8 137.0 4.4 2.04   3.1 1.02   GOT Bil-T Alb Lactic acid CRP LDH PT PTT Lipase   U/l mg/dl g/dl mmole/l mg/dl U/l sec Sec U/l 10/9 171.0 0.7 2.3 1.1     16.4/12.4 48.6/37.0   10/10 127.0 0.8 2.9       16.6/12.4 49.6/37.0   10/12 72.0 0.8     >12.0 1213 15.4/11.6 53.5/37.3 34.0 10/14 57.0 1.3         15.5/12.4 50.0/37.4     4. D-Dimer: 2.47 5.U/A:   Sp.Gr PH Pro. Glu. Ket. O.B. Urob. RBC WBC Epi. Cast Bac.       mg/dl g/dl     EU/dl  /HFL /HFL /HFL /LFL   10/11 1.026 7.5 100 - - + 1.0 10-15 5-10 0-2 - + 6.Pleural effusion:   Sp.Gr Riva. WBC RBC Alb. TP LDH Glu. TG Lipase       /ul /ul g/dl g/dl U/l mg/dl mg/dl U/l 10/12 1.020 + 100 10000 1.7 2.7 866.0 103 19.0 <1.0 7. Bronchioalveolar lavage:   Lipase TG Alb   U/l mg/dl g/dl 10/12 <1.0 <10 0.7 本病例為一長骨骨折手術後逐漸產生呼吸困難，意識不清，繼而進展至呼吸變竭之年輕病人，由病史及術後臨床表微看來，脂肪栓塞症候群 (Fat embolism syndrome) 應為第一個考慮之診斷。脂肪栓塞是長骨骨折外傷和髓內腔手術引發的潛在性嚴重威脅生命的一種合併症，病患會有：突然的意識改變、呼吸及心跳過速、發燒等症狀，嚴重者甚至死亡，此症候群之診斷大多以臨床症狀為主，但診斷之確立有時相當困難。實驗室的檢本常不具特殊性。至於治療方面通常以支持性為主。 繼續教育考題 1. (C) Which of the following descriptions of fat embolism syndrome is WRONG? A It is most likely to occur in patients with multiple long bone and pelvic fractures. It may also be associated with nontraumatic disorders. B Patients with fractures involving the middle and proximal parts of the femoral shaft are more likely to experience fat embolism. C Symptoms usually become evident within 46 hours after the trauma D Symptoms usually become evident within 24-48 hours after trauma 2. (B) Which symptoms/signs below are common manifestations of fat embolism syndrome? (1) Hypoxemia (2) elevated temperature (3) jaundice (4) neurological symptoms (5) hemorrhagic petechiae A (2), (3), (4) B (1), (2), (4), (5) C (1), (3), (4), (5) D (1), (2), (3), (4), (5) 3. (D) Which of the following descriptions of fat embolism syndrome is true? A Initial symptoms are probably caused by mechanical occlusion of multiple blood vessels with fat globules that are too large to pass through the capillaries. B The late presentation is thought to be a result of hydrolysis of the fat to more irritating free fatty acids which then migrate to other organs C Unlike other embolic events, the vascular occlusion in fat embolism is often temporary or incomplete since fat globules do not completely obstruct capillary blood flow D All of the above 4. (C) Which of the following descriptions of the pulmonary manifestations of fat embolism syndrome is WRONG?. A Chest X-ray may show evenly distributed, fleck-like pulmonary shadows (Snow Storm appearance), and dilatation of the right side of the heart. B Hypoxemia is present in nearly all patients C Hypoxemia in these patients has been attributed to impairment of diffusion and can be easily reversed by O2 supplement D Acute cor pulmonale is manifested by respiratory distress, hypoxemia, hypotension and elevated central venous pressure 5. (D) Which of the following CNS signs of fat embolism syndrome is true? A Change in level of consciousness is common B Usually nonspecific and have the features of diffuse encephalopathy: acute confusion, stupor, coma, rigidity, or convulsions. C Cerebral edema may contributes to the neurologic deterioration D All of the above 6. (C) Which of the following description about the hematological manifestations of fat embolism syndrome is WRONG? A DIC with thrombocytopenia and bleeding tendency are commonly B A petechial rash that appears on the upper anterior portion of the body, including the chest, neck, upper arm, axilla, shoulder, oral mucous membranes and conjunctivae is considered to be a pathognomonic sign of fat embolism syndrome C Petechiae may appear late in the course and often disappears within hours (may result from occlusion of dermal capillaries by fat) D None of the above 7. (C) Which of the following description about the laboratory findings of fat embolism syndrome is CORRECT? A Serum lipase is often elevated in these patients during acute stage can be used as a marker of disease severity B Blood lipid level is helpful for monitoring of the severity of the syndrome. C Examination of urine, blood and sputum with Sudan III staining may detect fat globules that are either free or in macrophages. D The presence of fat-containing macrophages in the BAL is specific for the diagnosis of fat embolism 8. (D) Which of the following description about the management of fat embolism syndrome is WRONG? A Treatment of fat embolism syndrome is mainly supportive B Oxygen delivery by O2 mask C Mechanical ventilation is required for severe cases D The use of PEEP is not recommended in fat embolism syndrome 9. (D) Which kind of drug has been shown to be effective for most patients with fat embolism syndrome? A Inhaled corticosteroid B Intravenous heparin C Antibiotics D None of the above 10. (A) About the prognosis of fat embolism syndrome, which statement below is WRONG? A Prognosis is worse than that of acute respiratory distress syndrome secondary to sepsis or pneumonia B Prognosis improved after the introduction of mechanical ventilator after 1970s C The current mortality rate is about 10% D Improvements in the surgical technique and post-op care of the fracture may reduce the incidence of fat embolism syndrome

答案解說 答案解說: 1.(C) 脂肪栓塞症候群是長骨骨折中一種不常見的合併症 脂肪栓塞症候群60%病人在受傷後二十四小時內發生，85%在受傷後四十八小時內發生，一般皆在受傷後三天內發生，典型症狀為低血氧是過度換氣、心跳加速 呼吸功能不足 不明原因的發燒 的代償不全症狀。 60%病人於受傷後二十四至四十八小時發現前胸、腋下、頸部、肩膀和結膜上出現微小平坦的紅色瘀斑，此種小紅斑不會因壓迫變白，可能為皮下毛細管被脂肪和血小板顆粒封閉引起，當病人平躺時瘀斑容易發生在病人甲狀腺動脈軸線上，瘀斑只持續四至六小時。 2.(B ) 理由如答案 (1) 解說。 3.(D) 脂肪栓塞症候群較早被接受的理論為機械理論，原因在外傷破壞了靜脈血管及骨髓內的脂肪細胞，骨折形成的血腫，增加了組織間隙壓力，使脂肪球進入血液循環，再進入肺微血管內使血管栓塞。其次被接受的為生物化學理論，因外傷引起交感神經分泌與壓力有關的Catecholamine, 能使脂肪從脂肪組織中釋出，並使乳糜小滴乳狀液的穩定性喪失，乳糜小滴合併成大脂肪滴，經破裂的血管進入血液循環及肺臟造成肺栓塞 4.(C) 脂肪栓塞時， 血流經過時，血小板、白血球、紅血球及纖維蛋白皆陷入小血管中，血小板可能釋放一種血管收縮劑Serotonin，，直接增加肺毛細管內膜損傷，引起肺壓增加，使液體和蛋白質滲漏進入肺間隙，產生肺分流Shunt，無論病人呼吸使用多少氧氣，都無法改善血流缺氧狀況，導致成人型呼吸窘迫ARDS的產生。臨床上嚴重度可由的低血氧至致死性的呼吸衰竭。低血氧是早期症狀。 胸部X光檢查可見瀰漫性間質浸潤，有時被形容為“暴風雪狀況”（Snow storm appearance） 5.(D) 75% 脂肪栓塞症候群病人發生神經狀況變化如昏睡、不安、混亂、痙攣或昏迷，可能原因為低血氧或腦部脂肪栓塞造成。 6.(C ) 脂肪和凝血質Thromboplastin由骨折部位釋出後，能激發凝血機轉使血小板凝聚。此外病患可能因外傷消耗Fibronectin，當Fibronectin不足時，血液中產生纖維蛋白退化產物（Fibrin degradation products）增加 7.(C ) 脂肪尿出現於60% 病人中，且大約於三天內出現。血液、痰、尿中含脂肪球等都是重要的評估資料。BAL 有fatcontaining macrophages 並非有診斷上之專一性 8.(D )。PEEP 之使用對脂肪栓塞症候群治療相當重要 9.(D ) 治療主要依靠使用氧氣罩或給予呼吸道插管及呼吸器 (high PEEP) 維持呼吸功能，可注射利尿劑以降低肺水腫，改善呼吸窘迫症狀。Steroid和Heparin的給予則有待進一步的觀察是否使用Steroid來預防脂肪栓塞症候群之發生仍有爭議，因Steroid可能造成免疫機能受損及致命的感染等合併症發生 10.(A ) 1970年以前脂肪栓塞症候群的死亡率在12%—35%，呼吸器的發明後，因能早期治療，已使死亡率降低至10%以下。 Top of Page