Hemorrhage in cerebral fat embolisms in a cat model using triolein dependent on the physical properties of triolein

Purpose

Hemorrhage is a finding of clinical fat embolism syndrome. The purpose of the present study was to evaluate the occurrence of hemorrhage in the cat brain by SW MR imaging after infusion of triolein as a bolus or as an emulsion into the carotid artery.

Materials and methods

Twenty-two cats were divided into two groups according to the type of triolein infused: group 1 (n = 11) was infused with a 0.1 ml triolein bolus, group 2 (n = 11) with triolein emulsion containing 0.1 ml triolein in 20 ml saline. SW imaging was performed before and after triolein infusion (at 2 h, 1 and 4 days). After MR imaging on day 4, cats were sacrificed and brains were immediately excised. Hemorrhage was evaluated using H&E staining.

Results

Hemorrhage was observed in eight cats in group 1, in no cats in group 2. Hemorrhage on SW images was found to correspond with light microscopy.

Conclusions

SW images revealed hemorrhage in lesion hemispheres infused with triolein bolus. However, there was no evidence of hemorrhage infused with emulsified triolein. Thus, the occurrence of hemorrhage in cerebral fat embolism may depend on fat status.     

Pulmonary fat embolism induced by exposure to high ambient temperature in rats with a fatty liver

The aim of this study was to investigate whether a fatty liver contributes to pulmonary embolism under a high ambient temperature. As an experimental model, we exposed fatty liver rats to a high temperature (45°C) and then looked for fat emboli in the alveolar capillaries using the fat-staining method. Fat emboli were detected in the alveolar capillaries of the fatty liver rats, but not in those of the normal liver rats. Moreover, the degree of pulmonary fat embolism tended to become more severe in proportion to the severity of the fatty liver. In addition, fat emboli did not appear at a core body temperature of 40°C, but were detected at a core body temperature of 44°C. From these results, we conclude that a fatty liver may contribute to the formation of pulmonary fat embolism and that high temperatures act as a trigger for the onset of pulmonary embolism. Moreover, it is possible that fatty liver affects the development of heat stroke induced by exposure to a high ambient temperature and that pulmonary fat embolism is a significant finding which helps to enable a diagnosis of heat stroke in autopsy cases.     

Relationship between pulmonary fat embolism and core body temperature in rats with a severe fatty liver

We previously demonstrated that pulmonary fat embolism was induced by elevation of the core body temperature, in rats with a fatty liver. The aim of the present examination was to investigate the core body temperature at which pulmonary fat embolism developed capillaries through exposure to a high temperature, in rats with a fatty liver. Following heat stress, pulmonary fat embolism was observed to a slight degree at a core body temperature of 41 and 42 degrees C, whereas the severity of pulmonary fat embolism was greatly increased and was classified as severe at a core body temperature of 43 degrees C. Moreover, the concentrations of aspartate aminotransferase and alanine aminotransferase within plasma were significantly increased at a core body temperature of 43 degrees C. These results clearly indicate that the development of pulmonary fat embolism could be related to hyperthermia at above 42 degrees C following heat stress, and that fat emboli may be derived from the fatty liver itself. It is thus likely that pulmonary fat embolism can be considered as one form of evidence of hyperthermia in an individual with a fatty liver.     

Frequency and outcome of pulmonary polymethylmethacrylate embolism during percutaneous vertebroplasty

BACKGROUND AND PURPOSE: During percutaneous polymethylmethacrylate (PMMA) vertebroplasty (PV), PMMA cement may migrate into the venous system and subsequently be transported to the pulmonary arteries. Frequency, outcome, and imaging findings of PMMA pulmonary embolism are poorly understood. We retrospectively assessed the frequency and outcome of PMMA embolism during PV in a large patient cohort and evaluated the relationship of the volume of injected PMMA to the occurrence of pulmonary PMMA embolism.MATERIALS AND METHODS: Between 2001 and 2007, 532 osteoporotic compression fractures in 299 consecutive patients were treated with PV. PMMA embolism was defined as venous PMMA migration toward the lungs visible on biplane fluoroscopy during PV. CT was performed immediately and 1 year after PMMA migration.RESULTS: Venous PMMA migration occurred during 11 PVs in 11 patients (2.1%, 95% confidence interval, 1.1–3.7%). CT in 8 patients demonstrated small peripheral pulmonary PMMA emboli. All 11 patients remained asymptomatic during 1-year follow-up. Repeat CT scanning after 1 year in 6 patients demonstrated unchanged pulmonary PMMA deposits without late reactive changes. Mean injected cement volume in patients with and without PMMA embolism was not different (3.6 ± 1.06 mL versus 3.3 ± 1.16 mL, P = .43). Similar comparison for thoracic and thoracolumbar vertebrae yielded P values of .07 and .9.CONCLUSION: Pulmonary PMMA embolism during PV is an infrequent complication without permanent clinical sequelae. After 1 year, no pulmonary reaction was seen on CT. No definite relationship of PMMA emboli with injected cement volume could be established.

Percutaneous polymethylmethacrylate (PMMA) vertebroplasty (PV) is increasingly used for pain relief in patients with symptomatic vertebral compression fractures. Since the introduction of PV in 1987, its safety and effectiveness have been confirmed in several studies.^1–6 Complications of PV are rare and, if they occur, are mostly related to PMMA leakage outside the treated vertebral body into adjacent anatomic structures. During PV, PMMA may migrate into the venous system and is subsequently transported to the pulmonary arteries. Frequency, outcome, and imaging findings of such PMMA pulmonary embolism are poorly understood.In this study, we retrospectively assessed frequency and clinical and imaging outcomes of PMMA embolism during PV in a large patient cohort. In addition, we evaluated whether the volume of injected PMMA is a risk factor for the occurrence of pulmonary PMMA embolism.     

犬急性骨水泥肺栓塞的实验研究

目的通过股静脉注入骨水泥建立犬急性肺栓塞模型,探讨一定剂量范围内不同量骨水泥肺栓塞引起的生理病理变化间的差异。方法 18只成年家犬随机分成A、B、C 3组,每组6只,麻醉后行胸部CT平扫,穿刺右股静脉、左股动脉并置入血管鞘,经静脉鞘注入聚甲基丙烯酸甲酯(PMMA)A组0.5 ml,B组1 ml,C组2 ml。于注入PMMA前和注入后即刻、30 min及1 h分别检测血气分析、平均肺动脉压;于注入PMMA前、后5 min行肺动脉造影。术后1h行胸部CT平扫+增强。术后2 h将犬处死,开胸解剖观察大体形态后,沿肺动脉分支方向随机取肺组织3块进行病理学检查。结果 18只实验犬经股静脉注入PMMA操作均成功,经CT及病理证实均成功建立急性骨水泥肺栓塞模型。各组实验犬动脉血氧分压、二氧化碳分压在骨水泥注入前后差异均无统计学意义(P>0.05)。仅C组骨水泥注入后即刻平均肺动脉压为(24.12±1.74)mmHg,注入后30 min为(23.84±1.25)mmHg,注入后1 h为(24.17±1.63)mmHg,均较注射前的(16.47±0.55)mmHg差异有统计学意义(P<0.05)。A组、B组平均肺动脉压在骨水泥注入前后差异均无统计学意义(P>0.05)。各组实验犬术后胸部CT平扫均可见两肺高密度影,下肺多见,C组尤为明显。部分实验犬平扫见条索状阴影及肺不张征象。C组部分实验犬胸部增强CT可见肺动脉小分支内部分充盈缺损。肺动脉造影仅C组部分实验犬出现肺内部分细小血管减少,血管纹理稀疏,未见肺动脉主干及分支的充盈缺损。病理学检查均发现肺动脉分支存在骨水泥栓子,未见继发血栓形成。结论≤2 ml的骨水泥致急性肺栓塞的严重程度与注入骨水泥剂量没有相关性。在心肺功能正常情况下,≤2 ml的急性骨水泥肺栓塞不会引起明显的呼吸功能障碍。     

脂肪栓塞综合征早期诊断方法

目的：探讨亚临床期脂肪栓塞的特点及诊断方法。方法：采用同种异体犬长骨骨髓脂肪静脉注射，建立实验模型。１４只健康杂种犬注射液体脂肪（０．７ｍｌ／ｋｇ）后，均发生脂肪栓塞综合征。结果：提出亚临床期脂肪栓塞综合征早期诊断新方法：从肺微血管血和周围静脉血中获取血凝块进行快速冰冻切片，经油红“Ｏ”染色后，镜检脂滴。经计算机图像分析证实，肺微血管中脂滴的数量和直径均明显高于周围静脉血。结论：本法具有较高的特异性和敏感性。结合动脉血氧分压下降，可作出亚临床期脂肪栓塞的早期诊断。     

Contrast medium injection optimisation in spiral CT for the diagnosis of pulmonary embolism

PURPOSE: Spiral CT, normally a highly accurate diagnostic method to diagnose pulmonary embolism, has its weak point in the synchronisation of contrast medium (CM) injection and the start of the acquisition, essential to obtain optimal vascular enhancement. The aim of this paper is to introduce a method to control the CM injection based on the enhancement of blood vessels in the diagnosis of pulmonary embolism. MATERIALS AND METHODS: The CARE bolus software pilots an electronic trigger that first monitors the CM passage, then starts the acquisition procedure when the intensity of enhancement reaches a pre-set value. Our spiral CT has a 6-second scan delay between the trigger's "go-ahead" and the start of the acquisition. During this interval, the CM reaches the pulmonary venous system, enhancing it and making the diagnosis of pulmonary embolism more difficult. This problem was overcome by injecting a slow bolus (30 ml; 1.5 ml/s flow rate) before the CM that triggers the start of the scan when the CM is only present in the pulmonary arteries. We examined 80 patients (36 men, 44 women, mean age 66.9, age range 18 to 89 years). All patients were examined for clinically, radiographically or scintigraphically suspected pulmonary embolism. We evaluated the enhancement of pulmonary arteries on a scale from 0 (poor) to 10 (excellent), image quality (excellent, fair, poor), the examination time and patient tolerance. The results were compared with those obtained in a group of 80 patients studied with CARE bolus without a timing bolus. RESULTS: Monitor scans were performed with the ROI that triggers the sequence centred on the right heart (trigger value set at 30/35 HU). There were no diagnostic artefacts caused by the enhancement of pulmonary veins due the timing bolus. The average time per procedure was less than 30 min and the time needed to reach the trigger value was 15 sec (range: 10-24 sec). The average volume of CM injected was 130 ml (timing bolus: 30 ml, scan bolus: 100 ml). There were no adverse events to CM injection. The arterial enhancement scored 7 to 10 for 45 patients (56%), 4 to 6 for 23 (28.5%) and 1 to 3 for 12 (15.0%). Image quality was excellent in 52 patients (65.0%), fair in 18 (22.5%) and poor in 10 (12.5%). Comparing arterial enhancement and image quality, we observed that in the cases where enhancement had scored 7 to 10, image quality was excellent, and in the 7 cases where image quality was poor, so was enhancement (1 to 3). We also made a comparison between procedures carried out with and without the timing bolus. We observed that the use of the timing bolus increases the number of exams with high scores for arterial enhancement, and therefore increases the overall number of examinations with optimal enhancement. DISCUSSION AND CONCLUSIONS: In order to be diagnostically useful, spiral CT requires good vascular enhancement and synchronisation of the start of acquisitions with the highest concentration of CM, as an incorrect scan delay will lead to artefacts and interpretation errors. The proposed method allows correct timing of the CM injection. The diagnostic bolus is preceded by a slow-flow timing bolus that is intercepted by the electronic trigger, which starts the scan when the CM passes into the right heart and pulmonary arteries. The slow-flow bolus volume was 30 ml injected at 1.5 ml/s, whereas the volume of the real bolus was 100 ml, injected at 4.5 ml/s. Monitor scans were performed with the trigger ROI centred on the right heart (trigger value set at 30/35 HU). The time needed for the complete spiral CT exam did not exceed 30 min. The first low-flow bolus injection takes approximately 10 min, but this time becomes shorter as the operator's experience grows. The correct positioning of the ROI on the right heart is the most time-consuming step in the procedure. The procedure was well accepted by all patients with no complaints due to the CM or to the duration of the procedure. There is a high level of concordance between arterial enhancement and image quality. In conclusion, the proposed method is simple, easy to reproduce, and does not give rise to interpretation problems. It is well accepted by patients and suffers few limitations, mainly represented by patients with severe cardiac arrhythmia.     

Prevalence of pulmonary thromboemboli among referred cadavers having hospitalization records to Tehran Legal Medicine Center

BACKGROUND: Pulmonary thromboemboli are one of the main causes of sudden death especially in hospitalized patients and appeared with different nonspecific manifestations. The aim of this study was to determine the prevalence of thromboemboli. MATERIALS AND METHODS: In this cross sectional study, pulmonary autopsies of 200 cadavers who were selected randomly from all cadavers with clinical suspicion of thromboemboli referred to Tehran University Tissue Archive in different months from January 2005 to 2006 and the prevalence of pulmonary embolism in these cases and its relation with demographic characteristics and sources of disease was assessed. Also, agreement degree of clinical and histopathological diagnosis of pulmonary embolism was calculated. RESULTS: The prevalence of pulmonary embolism was estimated at 13.5%. There were positive relationship between prevalence of pulmonary embolism and increased of age (P=0.001). Interpretation of results of macroscopic and histopathological studies for diagnosis of embolism showed moderate agreement (kappa=0.59) and interpretation of results of clinical diagnosis of disease before death and pathologic findings after death showed poor agreement (kappa=0.34). The most frequent detected location of emboli were end branches of pulmonary artery. CONCLUSION: Considering the apparent high prevalence of pulmonary embolism in our study, we recommend increased use of anti-deep vein thrombosis measures in all appropriate patients within the Tehran hospital population, according to evidence-based guidelines.     

Osmium impregnation detection of pulmonary intravascular fat in sudden death: A study of 65 cases

Pulmonary fat embolism is widely recognised in forensic pathology. Pulmonary fat embolism requires mobilisation of free fat, entry of free fat into the circulation and lodging of fat globules in fine venous capillaries. This paradigm of fat embolisation has been used to support the evidence of antemortem fat depot disruption when the presence of intravascular fat is confirmed at autopsy. However, sporadic reports of intravascular fat in various medical conditions, which contradict the above mechanism, have opened questions about the alternative pathogenesis. In this study, 65 cases of sudden deaths were examined for the presence of pulmonary intravascular fat (PIF) by osmium impregnation. Cases were selected based on the criteria that were designed to eliminate the possible confounding effect from medical intervention or postmortem changes. Slides were graded based on their ease of search and only the fat droplets confined by the blood vessel or capillary wall were considered as a positive finding. The results show surprisingly high PIF incidences of varying degrees in all the categories of sudden deaths. Further study is needed to devise criteria for diagnosis of fatal fat embolism since the histological appearance of the high-grade PIF in natural sudden death may not be easily distinguishable from the traumatic fat embolism.     

An improved radiolabeling technique of ivalon and its use for dynamic monitoring of complications during therapeutic transcatheter embolization

Transcatheter embolization by Ivalon particles for treatment of arteriovenous malformations has been an accepted therapeutic technique for many years. We describe a new and efficient radiolabeling technique of Ivalon particles using [99mTc]sulfur colloid. Continuous and dynamic monitoring of injected radiolabeled Ivalon particles is made possible by viewing the persistence scope of a portable gamma camera whose head is positioned over the patient undergoing therapeutic embolization. Therefore, if inadvertent pulmonary embolism or reflux migration of radiolabeled Ivalon particles has occurred, the angiographer is immediately aware of this potentially serious or fatal complication and can take corrective action. We describe two patients, each with an arteriovenous malformation, who had therapeutic embolization with radiolabeled Ivalon particles, one resulting in reflux migration and the other resulting in inadvertent pulmonary embolism.     

Nonfatal venous air embolism after contrast-enhanced CT

Contrast material-enhanced computed tomography (CT) was performed in 100 patients. Fifty milliliters of contrast material was intravenously injected by hand and followed by a drip infusion of 100 mL of contrast material. Venous air embolism occurred in 23% of the patients. The amount of embolism was minimal in 20 patients and moderate in three. Although large amounts of embolism have been reported to be associated with considerable morbidity and mortality, none of the patients in this study had immediate or delayed complications as a result of the small degree of embolism. The locations of the emboli were in the subclavian or axillary vein in nine, right or left brachiocephalic vein in three, internal jugular vein in two, superior vena cava in two, right ventricle in two, and main pulmonary artery in 12 patients. In patients at high risk for cerebral air embolism, such as those with intracardiac shunts or pulmonary arteriovenous malformations, extreme caution should be used--even in the routine administration of intravenous fluids or contrast media--to prevent venous air embolism and resultant neurologic deficits.     

Experimental cerebral fat embolism: embolic effects of triolein and oleic acid depicted by MR imaging and electron microscopy

BACKGROUND AND PURPOSE: In fat embolism, free fatty acid is more toxic than neutral fat in terms of tissue damage. We evaluated the hyperacute embolic effects of triolein and oleic acid in cat brains by using MR imaging and electron microscopy. METHODS: T2-weighted imaging, diffusion-weighted imaging, and contrast-enhanced T1-weighted imaging were performed in cat brains after the injection of triolein (group 1, n = 8) or oleic acid (group 2, n = 10) into the internal carotid artery. MR images were quantitatively assessed by comparing the signal intensity ratios of the lesions with their counterparts on T2-weighted images, apparent diffusion coefficient (ADC) maps, and contrast-enhanced T1-weighted images. Electron microscopic findings in group 1 were compared with those in group 2. RESULTS: Qualitatively, MR images revealed two types of lesions. Type 1 lesions were hyperintense on diffusion-weighted images and hypointense on ADC maps. Type 2 lesions were isointense or mildly hyperintense on diffusion-weighted images and isointense on ADC maps. Quantitatively, the signal intensity ratios of type 1 lesions in group 2 specimens were significantly higher on T2-weighted images (P =.013)/(P =.027) and lower on ADC maps compared with those of group 1. Electron microscopy of type 1 lesions in both groups revealed more prominent widening of the perivascular space and swelling of the neural cells in group 2, in contrast to notable endothelial defects in group 1. CONCLUSION: MR and electron microscopic data on cerebral fat embolism induced by either triolein or oleic acid revealed characteristics suggestive of both vasogenic and cytotoxic edema in the hyperacute stage. Tissue damage appeared more severe in the oleic acid group than in the triolein group.     

Reversible MR changes in the cat brain after cerebral fat embolism induced by triolein emulsion

BACKGROUND AND PURPOSE: Clinical cerebral-fat embolism shows both reversible and irreversible changes. We used MR imaging to investigate the reversibility of embolized lesions induced with a fat-emulsion technique and to evaluate the histologic findings. METHODS: A fat emulsion was made with 0.05 mL of triolein and 20 mL of normal saline and vigorous to-and-fro movement through a three-way stopcock. In 50 cats, the internal carotid artery was infused with the fat emulsion. Cats were divided into six groups on the basis of time delay after embolization: 1 hour; 1 and 4 days; and 1, 2, and 3 weeks. MR imaging and histologic examination were performed at these times. RESULTS: Embolized lesions were hyperintense on T2-weighted images, isointense or mildly hyperintense on diffusion-weighted images, isointense on apparent diffusion coefficient maps, and enhancing on gadolinium-enhanced T1-weighted images at 1 hour. These MR imaging findings were less evident at day 1 and reverted to normal after day 4 (isointense on all images). Electron microscopy showed minimal findings in the cortical lesion in groups 1 and 2 (group 1 at 1 hour and group 2 at 1 hour and 1 day). Light microscopic findings revealed evidence of necrosis-small focal gliosis and demyelination in the periventricular white matter-in only one cat. The number of intravascular fat globules was not significantly different between groups, as visualized by oil red O staining. CONCLUSION: Cerebral-fat embolism induced by a triolein emulsion revealed reversible MR findings and minimal histologic findings.     

螺旋CT在肺动脉栓塞诊断中的价值

目的:评价螺旋CT在诊断肺动脉栓塞中的作用。方法:16例肺动脉栓塞患者行螺旋CT肺动脉造影 (SCTA)检查,层厚3mm,扫描时间0.8s,对比剂注射速度3.5ml/s,总量100ml,扫描延迟时间15s。结果:16例 共644支,其中134支肺动脉及分支显示了栓塞,占20.8%。228支肺段肺动脉中,有56支显示肺动脉栓塞,占分 析肺动脉支的24.5%。204支亚段肺动脉中37支显示肺动脉栓塞,占分析肺动脉支15.4%。肺动脉栓塞的CT形 态:①直接征象为不同程度的肺动脉分支内充盈缺损。中心型充盈缺损17支,偏心型充盈缺损44支,附壁血栓型 34支,完全阻塞型39支。②间接征象胸膜下肺梗死灶,内乳动脉一侧增粗,肺纹理稀少,胸水,肺动脉高压。结论: 螺旋CT肺动脉造影是诊断肺动脉栓塞的快速、有效、无创伤的诊断方法。     

急性肺动脉栓塞患者CT阻塞指数与缺氧严重程度的相关性研究

目的:评价急性肺动脉栓塞患者CT阻塞指数(CTOI)与缺氧严重程度的相关性。方法:对24例急性肺动脉栓塞患者(栓塞组)的CT肺动脉造影(CTPA)资料进行回顾性分析,了解肺动脉CTOI与血氧饱和度(SO2)的相关性;以30例无栓塞的患者作为对照组,了解栓塞患者及无栓塞患者的SO2是否有差异;以SO2值94%为标准,将肺动脉栓塞患者分为缺氧组(<94%)和非缺氧组(≥94%),了解引起缺氧的肺动脉栓塞程度。结果:肺动脉栓塞组和对照组的SO2分别为:(89.96±7.68)%和(97.53±5.26)%,肺动脉栓塞组的SO2明显低于对照组(P<0.05);CTOI与SO2之间呈明显负相关(r=0.45,P=0.03),随着CTOI的增加,SO2降低越明显;肺动脉栓塞患者中,非缺氧组CTOI值的95%可信区间为0%～49.20%,缺氧组CTOI值的95%可信区间为39.88%～100%,CTOI值为40%～50%时,患者处于氧供不足的临界状态。结论:急性肺动脉栓塞患者CTOI与缺氧严重程度具有相关性,SO2值低于94%时,提示肺动脉栓塞超过约50%。     

Correlation of fat embolism severity and subcutaneous fatty tissue crushing and bone fractures

Pulmonary fat embolism (PFE) is frequently encountered in blunt trauma. The clinical manifestation ranges from no impairment in light cases to death due to right-sided heart failure or hypoxaemia in severe cases. Occasionally, pulmonary fat embolism can give rise to a fat embolism syndrome (FES), which is marked by multiorgan failure, respiratory disorders, petechiae and often death. It is well known that fractures of long bones can lead to PFE. Several authors have argued that PFE can arise due to mere soft tissue injury in the absence of fractures, a claim other authors disagree upon. In this study, we retrospectively examined 50 victims of blunt trauma with regard to grade and extent of fractures and crushing of subcutaneous fatty tissue and presence and severity of PFE. Our results indicate that PFE can arise due to mere crushing of subcutaneous fat and that the fracture grade correlated well with PFE severity (p = 0.011). The correlation between PFE and the fracture severity (body regions affected by fractures and fracture grade) showed a lesser significant correlation (p = 0.170). The survival time (p = 0.567), the amount of body regions affected by fat crushing (p = 0.336) and the fat crush grade (p = 0.485) did not correlate with the PFE grade, nor did the amount of body regions affected by fractures. These results may have clinical implications for the assessment of a possible FES development, as, if the risk of a PFE is known, preventive steps can be taken.     

Intravenous perfluorocarbon emulsion increases nitrogen washout after venous gas emboli in rabbits.

Intravenous perfluorocarbon emulsion (IV-PFC) has been shown to provide hemodynamic protection from gas embolism (Venous-VGE or arterial-AGE). The objective of this study was to investigate the mechanism of PFC protection from controlled VGE by quantifying the effects of IV-PFC emulsion on pulmonary elimination of nitrogen (N2). All rabbits received an intravenous pretreatment of PFC emulsion (Oxygent, 2.7 g/kg) or saline, then either a continuous room air infusion (0.25 ml/kg for 10 minutes) or a bolus of air (0.8 ml/kg within 10 seconds) through the femoral vein. Expiratory N2 peaked higher with PFC infusion immediately after air injection. The recovery to baseline of end tidal N2 was faster for PFC-treated animals (40 +/- 4.7 vs. 58 +/- 6.5 minutes). In PFC-treated animals, expired CO2, O2, arterial pressure and central venous pressure returned to baseline faster than the saline group. This study demonstrated that PFC increased pulmonary N2 washout. Correspondingly, PFC treatment better preserved the animals' hemodynamics after VGE injury. The use of IV-PFC promises to be a breakthrough non-recompression therapy for gas embolism in the treatment of Decompression Sickness (DCS) and in surgery.     

磷脂酰肌醇3-激酶在油酸型急性肺损伤大鼠肺内的表达及其意义

目的研究磷脂酰肌醇3-激酶（PI3-K）在油酸型急性肺损伤大鼠肺内的表达情况及其与肺组织细胞凋亡的关系。方法健康雄性SD大鼠60只,随机分为5组,每组12只：油酸组共4组,分别在尾静脉注入油酸0．25mi／kg后1h,2h,4h,24h颈总动脉放血处死,对照组：尾静脉注入生理盐水0．25ml／kg,2h颈总动脉放血处死。观察各组动脉血气、左肺湿／干比、肺系数、BALF中蛋白含量、肺通透指数,免疫组化法测定肺内Fas-L表达,免疫组化法和免疫印迹法测定肺内PI3-K蛋白表达。结果油酸组大鼠PaO2明显降低,左肺湿／干比、肺系数、BALF中蛋白含量及肺血管通透性明显增高（P〈0．01）,支气管、肺泡上皮细胞,肺血管内皮细胞,肺泡巨噬细胞上表达PI3-K和Fas-L明显增多（P〈0．01）,且PI3-K表达峰值时间早于Fas-L。结论Fas-L依赖的肺泡上皮细胞、肺血管内皮细胞和巨噬细胞凋亡参与早期ALI发病机制,此过程可能通过PI3-K信号转导通路予以实现。     

电子束CT在肺动脉栓塞治疗中的应用评价(附五例报告)

目的探讨肺动脉栓塞（ＰＥ）溶栓或手术治疗前后电子束ＣＴ（ＥＢＣＴ）检查的临床价值。方法３例急性ＰＥ行静脉溶栓治疗,２例慢性ＰＥ行肺动脉血栓及内膜清除术,所有病例均在治疗前１周及治疗后２周内行ＥＢＣＴ增强连续容积扫描,慢性ＰＥ尚作ＥＢＣＴ心脏电影。结果３例急性ＰＥ中２例在溶栓后ＥＢＣＴ复查示病灶基本消失,另１例首次溶栓后ＥＢＣＴ示病变无显著变化,遂更改治疗方案而奏效,血栓消失;２例慢性ＰＥ经手术治疗,ＥＢＣＴ证实病灶基本清除,心功能明显改善。结论ＥＢＣＴ对ＰＥ溶栓及手术治疗有重要的诊断和指导治疗价值,也是治疗后随访的可靠方法。     

Pulmonary embolism severity before and during the COVID-19 pandemic

Objectives:Early in the coronavirus 2019 (COVID-19) pandemic, a high frequency of pulmonary embolism was identified. This audit aims to assess the frequency and severity of pulmonary embolism in 2020 compared to 2019.Methods:In this retrospective audit, we compared computed tomography pulmonary angiography (CTPA) frequency and pulmonary embolism severity in April and May 2020, compared to 2019. Pulmonary embolism severity was assessed with the Modified Miller score and the presence of right heart strain was assessed. Demographic information and 30-day mortality was identified from electronic health records.Results:In April 2020, there was a 17% reduction in the number of CTPA performed and an increase in the proportion identifying pulmonary embolism (26%, n = 68/265 vs 15%, n = 47/320, p < 0.001), compared to April 2019. Patients with pulmonary embolism in 2020 had more comorbidities (p = 0.026), but similar age and sex compared to 2019. There was no difference in pulmonary embolism severity in 2020 compared to 2019, but there was an increased frequency of right heart strain in May 2020 (29 vs 12%, p = 0.029). Amongst 18 patients with COVID-19 and pulmonary embolism, there was a larger proportion of males and an increased 30 day mortality (28% vs 6%, p = 0.008).Conclusion:During the COVID-19 pandemic, there was a reduction in the number of CTPA scans performed and an increase in the frequency of CTPA scans positive for pulmonary embolism. Patients with both COVID-19 and pulmonary embolism had an increased risk of 30-day mortality compared to those without COVID-19.Advances in knowledge:During the COVID-19 pandemic, the number of CTPA performed decreased and the proportion of positive CTPA increased. Patients with both pulmonary embolism and COVID-19 had worse outcomes compared to those with pulmonary embolism alone.