多发伤患者氧代谢特点及临床意义

目的　探讨多发性外伤患者的氧动力学变化特点以及与临床转归的关系。方法　对 2 0 0 2 - 0 3～ 2 0 0 3- 0 5我科收治的多发伤患者 5 1例进行Swan -Ganz漂浮导管监测 ,并根据同时间点的动、混合静脉血氧分压、氧饱和度、血红蛋白等指标 ,计算出氧供、氧耗和氧摄取率。结果　MODS存活组和死亡组在创伤后 3～ 4d氧输送 (DO2 )逐渐上升 ,氧耗量也随之上升 ,出现病理性氧依赖 ,但 3～ 4d后MODS存活组患者随着DO2 的上升VO2 上升缓慢 ,出现“平台效应” ,死亡组VO2 随着DO2的上升而继续上升 ,仍显病理性氧依赖。结论　多发伤MODS患者氧摄取已出现明显障碍 ,导致VO2 对DO2 的病理依赖 ,治疗中应尽可能提高DO2 水平 ,可能会减轻多发伤患者MODS的发生和发展。     

重型乙型肝炎患者原位肝移植围手术期全身氧代谢的变化

目的 探讨重型乙型肝炎（乙肝）与其他肝病患者原位肝移植围术期全身氧代谢变化的特点。方法 12例重型乙肝患者为试验组。10例其他肝病患者为对照组。以咪唑安定、异丙酚、芬太尼、维库溴铵诱导全麻，术中吸入异氟醚维持麻醉。维库溴铵维持肌松，行改良背驼式原位肝移植术。左桡动脉穿刺测有创动脉压，右颈内静脉穿刺置入漂浮导管。分别于术前、无肝前10min、无肝期25min、新肝期30min和术毕监测动脉和混合静脉血氧分压（PaO2和Pv^-O2）、动脉和混合静脉血氧含量（CaO2和Pv^-O2）及动-静脉血氧含量差（CA-vO2）、氧供（DO2）、氧供指数（DO2I）、氧消耗（VO2）、氧耗指数（VO2I）、氧摄取指数（O2EI）和氧摄取率（O2ER）。结果 ①试验组：与术前相比，无肝前期Pv^-O2上升，Ca-vO2、O2EI、O2ER下降，DO2和VO2无明显变化；无肝期DO2、DO2I、VO2和VO2I均明显下降，DO2、VO2分别下降43％和21％，O2EI和O2ER均明显上升；新肝期PvO2上升，DO2和DO2I明显上升。VO2和VO2I回升至术前水平；术毕时DO2和DO2I依然高于术前水平。②对照组：无肝前期PvO2上升。DO2和VO2无明显变化，O2EI和O2ER下降；无肝期DO2、DO2I、VO2和VO2I均明显下降，DO2下降25％，VO2则下降12％；新肝期PvO2上升，Ca-vO2下降，DO2、DO2I明显上升，VO2和VO2I回升至术前水平；术毕时DO2和DO2I依然高于术前水平。结论肝移植围术期中，全身DO2变化大于VO2变化；重型乙肝患者的全身DO2和VO2变化较其他肝病患者剧烈。     

运动负荷气体交换法在老年人心肺功能状况评价中的应用

目的：比较正常组、慢阻肺组及冠心病组患者的心肺功能变化，评估无氧阈（AT）及相关指标在早期临床诊断及鉴别诊断的应用价值。方法：三组研究对象采用运动心肌功能仪和功率自行车，分别在AT时和峰值耗氧时刻，随机检测每人的AT出现时间，耗氧量（VO2）、公斤耗量（VO2／kg)、心率（HR）、通气量（VE）等心肺功能指标。结果：（1）AT出现时刻：冠心病组的AT出现时间明显早于正常组（P＜0．05），和慢阻肺组（P＜0．05），冠心病组的VO2/kg，VO2均明显地小于正常组与慢阻肺组（P＜0．05）；慢阻肺组的VE明显地小于正常组和冠心病组（P＜0．05）。（2）峰值耗氧时刻：慢阻肺组的VO2、VO2/kg和VE均明显地小于正常组（P＜0．05）。结论：在AT时，冠心病患者的AT出现时间明显提高，其VO2/kg和VO2均低于正常人，可做为早期诊断，指导康复治疗的指标，在峰值耗氧时刻，慢阻肺患者的VO2、VO2/kg和VE均明显小于正常人和冠心病患者，可做为评价心肺功能的病变程度的指标。     

颅脑外伤患者围手术期氧代谢特点及临床意义

目的:探讨颅脑外伤患者围手术期的氧动力学变化特点以及与临床转归的关系.方法:对2004年6月至2006年6月我科收治的8例颅脑外伤患者在围手术期进行Swan-Ganz漂浮导管监测,并根据同时间点的动脉、混合静脉血氧分压、氧饱和度、血红蛋白等指标,计算出氧供(DO2)、氧耗(VO2)和氧摄取率.结果:非多器官功能衰竭(MODS)患者随着DO2的上升VO2上升缓慢,出现"平台效应",MODS存活组和MODS死亡组VO2随着DO2的上升而继续上升,出现病理性氧依赖.结论:颅脑外伤MODS患者氧摄取已出现明显障碍,导致VO2对DO2的病理依赖,治疗中应尽可能提高DO2水平,可能会减轻颅脑外伤患者MODS的发生和发展.     

肿瘤患者外周血循环内皮细胞的检测及其临床意义

目的探讨循环内皮细胞（CEC）在肿瘤患者外周血中的变化及其临床意义。方法用流式细胞术检测48例健康对照者和80例肿瘤患者外周血中CEC的数量，并观察肿瘤缓解患者CEC数量的变化。结果（1）与健康对照组（2．42±1．33／μL）比较，肿瘤组CEC数量（4．38±3．52／μL）显著升高，差异有统计学意义（t=3．698，P〈0．001）；（2）肿瘤缓解组CEC数量（2．73±1．00／μL）显著低于未缓解组（4．33±2．17／μL）（t=3．488，P〈0．05）。结论CEC变化可能与肿瘤的发生、发展有密切的关系，有望作为肿瘤疗效观察的指标。     

多器官功能障碍综合征患者血管内皮损伤与炎性相关因子的研究

目的探讨多器官功能障碍综合征（MODS）患者循环内皮细胞（CEC）数量，凝血、纤溶指标和炎性相关因子的变化及其相关性。方法35例MODS患者为MODS组，20名健康体检者作为正常对照组。用Percoll密度梯度离心法分离血CEC，检测血浆凝血酶原时间（PT）、活化部分凝血活酶时间（APTT）、纤维蛋白原（FG）、D-二聚体以及血清肿瘤坏死因子-α（TNF-α）和白细胞介素-6（IL-6）水平。动态观察CEC、TNF-α和IL-6的变化，并分析CEC、TNF-α和IL-6与PT、APTT、FG和D-二聚体之间的相关性。结果与正常对照组比较，MODS组CEC数量明显增加。血清TNF-α、IL-6水平亦明显升高，PT、APTT延长，FG下降，血浆D-二聚体升高，差异均有显著性（P均〈0．05）。CEC数量及血清TNF-α、IL-6水平随时间延长逐渐增加；CEC数量与TNF-α、IL-6水平呈显著正相关（r1=0．536，P1=0．000；r2=0．412，P2=0．002），与PT、APTT、FG、D-二聚体间未发现相关关系；TNF-α、IL-6与PT、APTT呈显著正相关，与FG、D-二聚体无明显相关性。结论MODS患者血中炎性相关因子水平增加，血管内皮细胞功能受损，炎性相关因子在血管内皮损伤中起关键作用，CEC数量增加与炎症引起的血管内皮损伤有关。     

感染性休克患者早期氧代谢变化及其与预后的关系

目的 :了解感染性休克患者早期氧代谢变化 ,主要包括DO2 ,VO2 及动脉血乳酸的代谢状况 ,并评价其与预后的关系 ,方法 :感染性休克后患者 2 6例 ,经立即扩溶、给予血管活性药物尽早稳定循环后 ,并置Swan Ganz导管 ,平均放置时间为 76 8h ,测定CI后立即行血气分析和混合静脉血气分析 ,计算出DO2 ,VO2 并测定当时的动脉血乳酸值。结果 :全组中 12例存活 ,14例死亡 ,存活组初次DO2 及末次DO2 均明显高于死亡组 ,用初次DO2 ≥ 6 0 0ml/m2 ·min评价患者预后 ,其敏感性为 87 5 % ,特异性 5 8 3% ;存活组初次及末次VO2 相近 ,分别与死亡组初次和末次VO2 比较 ,亦无明显差异 ;存活组和死亡组初次血乳酸接近 ,均高于正常 ,存活组血乳酸值在感染性休克早期经过一段升高的过程后逐步降低 ,而后恢复到正常水平 ,死亡组却继续增高直至死亡。结论 :在感染性休克早期 ,患者存在“缺陷性氧耗”现象 ,VO2 不能作为评价患者预后的指标 ;在不使用大剂量Dopamine或Dobutamine的情况下 ,初次DO2 高者 ,预后较好 ;初次血乳酸水平不能反映预后 ,血乳酸代谢的时间过程能较好的反映预后     

参附注射液对心源性休克犬血流动力学及氧代谢的影响

目的观察参附注射液对实验犬心源性休克血流动力学及氧代谢的影响。方法制备犬心源性休克模型，制模成功后随机分为参附组、多巴胺组和对照组。于制模前，制模成功（用药即刻），用药后30、60、90、120和180min通过Swan-Ganz导管监测血流动力学，包括心排血量（CO）、肺动脉嵌顿压（PAWP）、肺动脉压（PAP）、中心静脉压（CVP）、心率（HR）、动脉压，并计算每搏量（SV）、每搏功（SW）、平均动脉压（MAP）、全身血管阻力（SVR）、肺循环阻力（PVR）；抽取动脉血及混合静脉血测定氧代谢动力学指标，包括DO2（氧输送），VO2（氧消耗）及ERO2（氧摄取率）。结果①与用药即刻比较，对照组CO、SV、SW、HR、MAP在给药后均呈进行性下降，而PVR、PAWP、CVP呈进行性升高（P均〈0．01）。②静脉注射参附注射液后CO、SV、SW均明显增加，60min时达到最高，然后逐渐下降（P均〈0．01）；HR、MAP在用药后呈进行性下降；SVR、PVR 30min降到最低后开始逐渐升高，120min到达用药前状态；PAWP较对照组降低明显（P均〈0．01）。③静脉注射多巴胺后CO、SV、SW、MAP、HR均增加，30min达到最高，但升高幅度较参附注射液组低（P〈0．05）；SVR、PAWP较参附组明显增加（P〈0．05）。④在用药即刻3组VO2与DO2均低于用药前，ERO2代偿增高。与多巴胺组比较，参附组DO2、VO2时显著升高（P〈0．05或P〈0．01），ERO2则明显下降（P〈0．05）。结论参附注射液较多巴胺在增加CO，降低外周阻力、肺动脉阻力、PAWP和HR，以及改善组织灌注与氧代谢能力方面具有明显的优势。     

抑制一氧化氮合成对犬感染性休克的影响

目的：探讨一氧化氮（NO）在感染性休克中的作用机制，及抑制NO合成的治疗学意义。方法：10只健康杂种狗予戊巴比妥麻醉，大肠杆菌内毒素（LPS）60μg·kg-1·h-1×30min静脉滴注，继以生理盐水（NS）15ml·kg-1·h-1维持。随机分成两组。组Ⅰ、组Ⅱ在LPS开始注射后60min分别单剂注射NS30ml、NS30ml＋L-硝基精氨酸（LNNA）20mg·kg-1。观察血液动力学、氧动力学、尿NO3/NO2（NOx）、血浆内皮素（ET）变化。结果：LPS注射后60min两组动物均呈典型高动力状态，平均动脉压（MAP）、体循环阻力（SVRI）明显下降，心脏指数（CI）轻度增加。LPS使氧输送（DO2）、氧耗（VO2）增加。尿NOx升高。LNNA使MAP恢复至基础水平，SVRI、PVRI显著升高且超过基础值；CI下降，DO2、VO2减少，PvO2上升，尿NOx低于组Ⅰ，而ET明显高于组Ⅰ。结论：LPS诱导的犬感染性休克的血液动力学异常与NO过多释放有关，NO抑制LPS引起的ET释放。LNNA虽可逆转低血压，但对感染性休克的整体治疗不利。     

体外循环中空气法胃粘膜pH值与氧供 氧耗的变化

目的观察体外循环（CPB）中空气法胃粘膜pH值与氧供、氧耗的变化了解体外循环期间胃粘膜的血流灌注。方法选择择期行体外循环心脏手术30例，麻醉后置入TONO胃管通过空气法胃粘膜张力模块自动持续监测胃粘膜二氧化碳分压（PgCO2），在监护仪中输入麻醉诱导后30min、体外循环30min、60min、停体外循环后30min和60min时间点的动脉和混合静脉血气分析结果，计算获得各时点的胃粘膜pH值（pHi）、氧供（DO2）和氧耗（VO2）等数据。结果PgCO2在CPB期间明显低于术前（P〈0．01），停CPB后恢复到术前水平；pHi的变化体外环循期间显著升高（P〈0．01），停CPB后恢复术前水平；DO2和VO2变化：CPB期间明显低于术前（P〈0．01），停CPB后明显高于CPB期间（P〈0．01），停CPB 60min后明显高于术前（P〈0．01）。结论本研究中的病例在低温体外循环期间未存在胃肠粘膜血流灌注不足。     

Significance of pathologic oxygen supply dependency in critically ill patients: Comparison between measured and calculated methods

Objective Oxygen supply dependency at normal or high oxygen delivery rate has been increasingly proposed as a hallmark and a risk factor in critical illnesses. We hypothesized that as fas as an adequate oxygen delivery is provided, oxygen consumption, when determined by indirect calorimetry, is not dependent on oxygen delivery in critically ill patients whereas calculated oxygen consumption is associated with artefactual correlation of oxygen consumption and delivery. Design Oxygen delivery, oxygen consumption and their relationship were analyzed prospectively. Metabolic data gained from both measured and calculated methods were obtained simultaneously before and after volume loading. Setting The study was completed in the intensive care unit as part of the management protocol of the patients. Patients 32 consecutive patients entered the study and were divided into 3 groups according to a clinical condition known to favour oxygen supply dependency: sepsis syndrome, adult respiratory distress syndrome and acute primary liver failure. Intervention The rise in oxygen delivery was obtained by colloid infusion (oxygen flux test) performed in hemodynamically and metabolically stable patients. All were mechanically ventilated. No change in therapy was allowed during the test. Measurements and results Oxygen consumption was simultaneously evaluated by calculation (Fick Principle) and direct measurement using indirect calorimetry. Oxygen delivery was derived from the cardiac output (thermodilution) and arterial content of oxygen. Oxygen supply dependency was considered while observing an increase in oxygen delivery greater than 45 ml/min·m². Irrespective of patient's clinical diagnosis and outcome, measured oxygen uptake remained unaltered by volume infusion whereas both oxygen delivery and calculated oxygen consumption increased significantly. Arterial lactate level>2 mmol/l and measured oxygen extraction ratio>25% failed to identify oxygen supply dependency when measured data were considered. Conclusion Analysis of oxygen uptake, when measured by indirect calorimetry, failed to substantiate oxygen supply dependency in the vast majority of the critically ill patients irrespective of diagnosis and outcome. Mathematical coupling of shared variables accounted for the correlation between oxygen delivery and calculated oxygen consumption.     

Muscle perfusion and oxygen consumption by near-infrared spectroscopy in septic-shock and non-septic-shock patients

OBJECTIVE: To measure muscle blood flow (Qtis) and oxygen consumption (VO(2)tis) in septic and non-septic critically ill patients by near-infrared spectroscopy (NIRS). SETTING: Surgical intensive care unit of a university hospital. PATIENTS AND PARTICIPANTS: Four patients with septic shock, eight post-surgical critically ill patients and ten healthy volunteers. MEASUREMENTS AND RESULTS: Oxyhaemoglobin (HbO(2)) and deoxyhaemoglobin (HbH) variations after venous occlusion were measured by NIRS in the brachioradialis muscle. We calculated Qtis by the rate of HbO(2) and HbH increase in the first 30 s of venous occlusion divided by haemoglobin blood concentration. VO(2)tis was calculated by subtraction of the arterial HbH from the initial increase of HbH after venous occlusion extrapolated to 1 min. Tissue oxygenation index [TOI = HbO(2)/(HbO(2)+HbH)] was also measured before venous occlusion. Two measurements in patients with septic shock, and one measurement in non-septic-shock patients and healthy subjects, were obtained. Of the measurements, 35% were repeated because of low-quality NIRS signal. VO(2)tis and Qtis were two times larger ( P<0.05) in patients with septic shock than in patients without and in healthy subjects. The TOI was very similar among the three groups. CONCLUSION: In septic-shock patients the increase in VO(2)tis was associated with an equivalent increase in Qtis. Therefore, tissue O(2) supply does not seem to be a limiting factor for muscle O(2) consumption. NIRS combined with venous occlusion allows a rapid, non-invasive and simultaneous assessment of regional perfusion and oxygen consumption. In case of microcirculatory shunt occurrence, the TOI should be cautiously used to assess tissue oxygenation state.     

Respiratory and cardiovascular responses to manual chest percussion in normal subjects

The respiratory and cardiovascular responses to manual chest percussion were studied in seven naive healthy subjects. Percussion during quiet breathing, percussion with thoracic expansion exercises (TEE) and TEE alone were applied to subjects in side-lying. Inspired volume, oxygen consumption, oxygen saturation, heart rate and blood pressure were measured before, during and after each technique. Significant increases in inspired volume and heart rate occurred with all three techniques (p < 0.01). Oxygen consumption increased with all three techniques however only the increases during percussion with TEE, and TEE alone were significant (p < 0.01). Oxygen saturation increased with percussion with TEE and TEE alone (p < 0.01). No significant changes in blood pressure were observed.     

Red cell transfusion therapy in the critical care setting

According to our own experience and published reports the frequency of red cell transfusion in intensive care units is in the range of 0.2 to 0.4 units per patient per day and is dependent upon the local strategy, the patients involved and the kind of surgery performed. The rationale for red cell transfusion is to maintain or restore the oxygen carrying capacity of the blood to avoid tissue hypoxia which occurs when oxygen delivery drops below a certain critical value. Besides bleeding, phlebotomy is also a significant source of blood loss in critically ill patients. According to several recent reviews and consensus articles there is no basis for a fixed indicator for transfusion, such as a haemoglobin concentration of < 100 gL-1. The decision to transfuse has to be made according to the patients individual status. The major adaptive mechanism in response to acute anaemia is an increase in cardiac output and hence blood flow to tissues. As a consequence even moderate degrees of acute anaemia may not be tolerated by patients with cardiac disease, whilst marked anaemia carries a considerable risk of ischaemia in patients with brain lesions or cerebral arterial stenoses. In critically ill patients it has been postulated that supply dependency of oxygen consumption occurs over a wide range of oxygen delivery, far above the critical values of oxygen delivery seen under normal conditions. Maximising oxygen delivery was therefore formulated as a goal in these patients. However, whether pathological supply dependency of oxygen delivery really exists in critically ill patients is still under discussion and recent studies found no benefit in maximising oxygen delivery to this patient group. However, individualised triggers for red blood cell transfusion are adequate for critically ill patients considering their co-morbidities and severity of disease. Finally, the decision to transfuse must also take into account the potential risks (infectious and non-infectious), as well as benefits for the individual patient. In the future, the level of transfusions may be reduced by using blood sparing techniques such as blood withdrawal in closed systems, bedside microchemistry, intravascular monitors, or autotransfusion of drainage blood in intensive care units.     

Hemodynamic and oxygen transport response to modified fluid gelatin in critically ill patients

The hemodynamic and oxygen transport effects of the rapid infusion of 500 ml of modified fluid gelatin, an artificial colloid widely used in Europe, were studied in a group of critically ill patients suffering from cardiovascular instability. Oxygen consumption tended to increase. There were no significant changes in heart rate, shunt fraction, or systemic vascular resistance index. There were significant increases in mean arterial pressure, pulmonary artery wedge pressure, stroke index, cardiac index, and oxygen delivery. There were significant decreases in Hgb concentration and arterial oxygen content. The overall circulatory effects of modified fluid gelatin are beneficial.     

重症超声:血流动力学的推手

随着临床研究和基础研究的不断深入, 研究者们对重症患者诊疗评价指标的认知不断提高, 发展至今, 重症患者的治疗已然从群体化、个体化治疗发展到器官化治疗阶段, 直接评估器官血流并以器官血流及功能改善为目标的治疗方式越来越多地应用于重症患者临床诊治。重症超声作为重症患者治疗的重要监测和评价方式, 在器官化治疗方面发挥着不可替代的作用, 不断推动着重症医生对疾病的认知和评价方式。重症超声的应用, 革新了人们对全身氧输送的认知, 深化了对心肺以及其他重要脏器血流动力学的理解, 同时推动了重症患者的临床诊治。如何更好地应用重症超声, 精细对器官血流动力学的评价, 是重症医生面临的重要问题。本文拟从全身氧输送及器官血流评估两方面, 系统阐述重症超声发挥的重要作用及应用方法, 以期为临床医生提供借鉴和参考。     

ABO blood type: a window into the genetics of acute respiratory distress syndrome susceptibility

The genetic factors that determine a patient’s risk for developing the acute respiratory distress syndrome (ARDS) remain understudied. In this issue of the JCI, Reilly and colleagues analyzed data from three cohorts of critically ill patients and observed an association between the ABO allele A1 and the onset of moderate-severe ARDS. This association was most notable in patients with non-pulmonary sepsis (an indirect, vasculature-targeted mechanism of lung injury) and persisted in patients who lacked epithelial expression of the A antigen, suggesting an endothelial mechanism of A1-associated ARDS susceptibility. Critically ill patients with blood type A had increased circulating concentrations of endothelium-derived glycoproteins such as von Willebrand factor and soluble thrombomodulin, and marginal lungs from blood type A donors were less likely to recover function during ex vivo perfusion. These findings implicate A antigen glycosylation of endothelial cells as a critical, genetically determined risk factor for indirect lung injury that may contribute to the mechanistic heterogeneity of ARDS.     

Angiotensin (1−7) peptide replacement therapy with plasma transfusion in COVID-19

AimTo determine whether convalescent angiotensin (1?7) peptide replacement therapy with plasma (peptide plasma) transfusion can be beneficial in the treatment of critically ill patients with severe coronavirus 2 (SARS-CoV-2) infection.Study designCase series of 9 critically ill patients with laboratory-confirmed COVID-19 who met the following criteria: severe pneumonia with rapid progression and continuously high viral load despite antiviral treatment.Peptide plasma: Plasma with angiotensin (1?7) content 8–10 times higher than healthy plasma donors was obtained from suitable donors. Peptide plasma transfusion was applied to 9 patients whose clinical status and/or laboratory profile deteriorated and who needed intensive care for 2 days.ResultsIn our COVID-19 cases, favipiravir, low molecular weight heparin treatment, which is included in the treatment protocol of the ministry of health, was started. Nine patients with oxygen saturation of 93% and below despite nasal oxygen support, whose clinical and/or laboratory deteriorated, were identified. The youngest of the cases was 36 years old, and the oldest patient was 85 years old. 6 of the 9 cases had male gender. 3 cases had been smoking for more than 10 years. 4 cases had at least one chronic disease.In all of our cases, SARS CoV2 lung involvement was bilateral and peptide plasma therapy was administered in cases when oxygen saturation was 93% and below despite nasal oxygen support of 5 liters/minute and above, and intensive care was required. Although it was not reflected in the laboratory parameters in the early period, 8 patients whose saturations improved with treatment were discharged without the need for intensive care. However, a similar response was not obtained in one case. Oxygen requirement increased gradually and, he died in intensive care process. An increase of the platelet count was observed in all cases following the peptide plasma treatment.ConclusionIn this preliminary case series of 9 critically ill patients with COVID-19, administration of plasma containing angiotensin (1?7) was followed by improvement in their clinical status. The limited sample size and study design preclude a definitive statement about the potential effectiveness of this treatment, and these observations require evaluation in clinical trials.     

Admission angiopoietin levels in children with septic shock

Angiopoietin (angpt) 1 and angpt-2 are circulating proteins first ascribed opposing roles in embryonic angiogenesis. Both bind the tyrosine kinase with immunoglobulin-like loop and epidermal growth factor homology domains (Tie) 2 receptor on endothelial cells, but angpt-1 is a Tie-2 agonist, whereas angpt-2 antagonizes Tie-2 signaling. In the developed vasculature, angpt-1 protects against vascular leak, whereas angpt-2 promotes increased vascular permeability. Because alterations in vascular permeability are common in septic shock, we obtained plasma from critically ill children within 24 h of diagnosis of the systemic inflammatory response syndrome (SIRS, n = 20), sepsis (n = 20), or septic shock (n = 61), as well as 15 healthy controls. Plasma levels of angpt-1 and angpt-2 were measured via a commercially available enzyme-linked immunosorbent assay. Plasma angpt-2 levels were significantly elevated in children with septic shock when compared with healthy children, as well as critically ill children with either SIRS or sepsis, and circulating angpt-2 levels seemed to correlate with disease severity and outcome. In addition, plasma angpt-1 levels were significantly decreased in critically ill children with septic shock compared with critically ill children with either SIRS or sepsis. Given the contrasting effects of angpt-2 and angpt-1 on the vascular endothelium, these two factors may play an important role in the pathophysiology of septic shock in children, and further studies are warranted.     

Efficacy of red blood cell transfusion in the critically ill

This article has evaluated the published data regarding the efficacy of RBC transfusions in the critically ill. Taken together, these studies generally support conservative RBC transfusion strategies in critical care to reduce the risk of transfusion-related adverse effects. The TRICC trial has established the safety ofa restrictive transfusion strategy, suggesting that physicians could minimize exposure to allogeneic RBCs by lowering their transfusion threshold. Further research will add to the generalizability of this study and explore the possible mechanism to explain why RBC transfusions do not improve outcomes in the critically ill. Additional studies will be necessary to determine the effects of RBC storage time and the presence of allogeneic leukocytes in allogeneic RBC. The following conclusions are evident: 1. RBC transfusion does not improve tissue oxygen consumption consistently in critically ill patients, either globally or at the level of the micro-circulation. 2. RBC transfusion is not associated with improvements in clinical outcome in the critically ill and may result in worse outcomes in some patients. 3. Specific factors that identify patients who will improve from RBC transfusion are difficult to identify. 4. Lack of efficacy of RBC transfusion likely is related to storage time, increased endothelial adherence of stored RBCs, nitric oxide binding by free hemoglobin in stored blood, donor leukocytes, host inflammatory response, and reduced red cell deformability.