Absence of supply dependence of oxygen consumption in patients with septic shock

We tested whether oxygen consumption ( o₂) was dependent on oxygen delivery ( o₂) in 10 patients with septic shock when o₂ was changed by the use of the inotropic agent, dobutamine. The mean acute physiology and chronic health evaluation (APACHE) II score of the patients was 27.3 ± 8.1 with a mean blood pressure on entry of 66.8 ± 12.4 mm Hg, and all had been volume resuscitated to a pulmonary artery occlusion pressure of greater than 10 mm Hg. We measured o₂ by analysis of respiratory gases NOW) while calculating o₂ by the Fick equation NOV) at three different OZ deliveries. When the dobutamine infusion rate was increased from 2.5 ± 4.0 to 12.3 ± 6.0 μg/kg/min, thermodilution cardiac output increased from 7.7 ± 2.6 to 10.1 ± 2.7 L/min (P < .01). Accordingly, dobutamine increased o₂ from 13.5 ± 3.8 to 18.2 ± 4.3 mL/min per kg (increase of 36.4% ± 19.7%; P < .01), but o_2G did not increase (3.2 ± 0.5 to 3.2 ± 0.6 mL/ min per kg). During these same interventions, the o_2F tended to increase (2.9 ± 0.7 to 3.4 ± 0.8 mL/min per kg, P < .06), presumably a spurious correlation because of measurement errors shared by the calculation of o_2F and o₂. Neither lactic acidosis nor acute respiratory distress syndrome (ARDS) conferred supply dependence of o_2G, but the presence of ARDS was predictive of death in this cohort. It is concluded that o₂ is independent of o₂ in patients with septic shock and lactic acidosis. These data confirm that maximizing o₂ beyond values achieved by initial fluid and vasoactive drug resuscitation of septic shock does not improve tissue oxygenation as determined by respiratory gas measurement of o₂.     

Systemic and microcirculatory effects of dobutamine in patients with septic shock

Purpose

The aim of this study was to characterize the cardiovascular responses to dobutamine and their predictors. Our hypotheses were that dobutamine mainly produces tachycardia and vasodilation and fails to improve the microcirculation of patients with septic shock.

Materials and Methods

Systemic hemodynamics and sublingual microcirculation were evaluated with dobutamine (0, 2.5, 5.0, and 10.0 μg kg^− 1 min^− 1) in 23 patients with septic shock.

Results

Dobutamine increased heart rate, cardiac index, and stroke volume index (SVI). Mean blood pressure was unchanged, and systemic vascular resistance decreased. Individual responses were heterogeneous. Stroke volume index increased in 52% of the patients. These patients showed lower changes in mean blood pressure (3 ± 16 mm Hg vs − 10 ± 6 mm Hg, P < .05) and higher increases in cardiac index (1.47 ± 0.93 L m^− 1 m^− 2 vs 0.20 ± 0.5 L m^− 1 m^− 2) than did nonresponders. Changes in SVI significantly correlated with echocardiographic left ventricular ejection fraction (r = 0.55). In the whole group, perfused capillary density remained unchanged (14.0 ± 4.3 mm/mm² vs 14.8 ± 3.7 mm/mm²), but improved if basal values were 12 mm/mm² or less (9.1 ± 4.3 mm/mm² vs 12.5 ± 4.8 mm/mm²).

Conclusions

Dobutamine produced variable hemodynamic effects. Systolic dysfunction was the only variable associated with increases in SVI. Finally, dobutamine only improved sublingual microcirculation when severe alterations were found at baseline.     

The effects of norepinephrine infusion on oxygen consumption in a patient with septic shock

A 65-year-old man developed postsurgical septic shock, unresponsive to plasma volume expansion and administration of dopamine and dobutamine. A continuous norepinephrine infusion was then started and the dose increased to 0.62 g·kg^–1·min^–1 until the mean arterial pressure was 70 mmHg. Prior to and during the norepinephrine infusion, oxygen consumption was continuously measured with a mass spectrometer system. There was a parallel increase in mean arterial pressure and oxygen consumption (+35%). There was also an increase in cardiac index and oxygen delivery. Systemic vascular resistance was only transiently increased. In this case with septic shock, norepinephrine infusion improved hemodynamic variables with an associated increase in oxygen consumption.     

Heterogeneity and prediction of hemodynamic responses to dobutamine in patients with septic shock

OBJECTIVE: To establish the heterogeneity of hemodynamic responses to dobutamine in patients with septic shock and to identify the predictive factors of these hemodynamic responses. DESIGN: Prospective study. SETTING AND PATIENTS: A total of 12 patients with septic shock in a tertiary medical intensive care unit. INTERVENTIONS: A 20-min dobutamine infusion at 5 microg.kg(-1).min(-1) with subsequent increments to 8, 12.6, and 20 microg.kg(-1).min(-1), on two consecutive days. Responses were dichotomized into changes in heart rate (HR) or stroke volume index (SVI) of >10% and < or =10% at the maximal dobutamine infusion. MEASUREMENTS AND MAIN RESULTS: No differences were found in survival, Acute Physiology and Chronic Health Evaluation II score, maximal dobutamine doses, or pharmacokinetics of dobutamine between HR and SVI groups. In DeltaHR > 10% vs. DeltaHR < or = 10%, baseline HR was lower, and baseline mixed venous oxygen tension and saturation were higher. During dobutamine infusion, mean arterial pressure decreased in DeltaHR > 10%. Cardiac index and the systemic oxygen delivery index increased and the systemic vascular resistance index decreased at unchanged SVI. Pressure work index increased and the ratio of the diastolic to systolic aortic pressure time indices decreased but not to <0.6. In DeltaHR < or = 10%, systemic vascular resistance index and the ratio of the diastolic to systolic aortic pressure time indices decreased (but remained >0.6) without changes in SVI or cardiac index. Baseline hemodynamic and metabolic variables did not differ between SVI groups. In DeltaSVI > 10%, cardiac index increased with dobutamine, but Pao2 and the systemic oxygen delivery index decreased. In DeltaSVI < or = 10%, HR and the systemic oxygen delivery index increased; mean arterial pressure, left ventricular stroke work index, systemic vascular resistance index, and the ratio of the diastolic to systolic aortic pressure time indices decreased. CONCLUSIONS: Patients with a positive chronotropic response to dobutamine had lower baseline HR values, and a chronotropic rather than inotropic response predicted an increase in cardiac index and systemic oxygen delivery index. Incremental dosages of dobutamine did not compromise indirectly measured myocardial oxygen balance.     

Oxygen delivery and consumption in patients with hyperdynamic septic shock

We analyzed the relationship of increases in oxygen delivery to changes in oxygen consumption in ten patients with hyperdynamic septic shock. Increases in oxygen delivery from 413 +/- 14 (SEM) to 535 +/- 19 ml/min X m2 (p less than .01) were associated with increases in oxygen consumption from 136 +/- 10 to 161 +/- 5 ml/min X m2 (p less than .05). Arterial lactate decreased from 4.6 +/- 1.6 to 2.1 +/- 0.3 mmol/L (p less than .05). These observations suggest that oxygen utilization is perfusion-limited in hyperdynamic septic shock.     

Effect of blood transfusion on oxygen consumption in pediatric septic shock

Treatment plans for pediatric septic shock advocate increasing oxygen consumption (VO2). Recent studies in septic shock indicate that improving oxygen delivery (DO2) by increasing blood flow will increase VO2. We prospectively examined the effect on VO2 of improving DO2 by increasing oxygen content (CO2) with blood transfusion in eight hemodynamically stable septic shock patients. Transfusion consisted of 8 to 10 ml/kg of packed RBC over 1 to 2 h. Hemodynamic and oxygen transport measurements were obtained before and after blood transfusion. Transfusion significantly (p less than .05) increased Hgb and Hct from 10.2 +/- 0.8 g/dl and 30 +/- 2% to 13.2 +/- 1.4 g/dl and 39 +/- 4%, respectively (mean +/- SD). DO2 significantly (p less than .05) increased after transfusion (599 +/- 65 to 818 +/- 189 ml/min.m2), but VO2 did not change (166 +/- 68 to 176 +/- 74 ml/min.m2; NS). In pediatric septic shock patients, increasing CO2 by blood transfusion may not increase VO2.     

去甲肾上腺素联合多巴酚丁胺对感染性休克患者胃粘膜灌注的作用

目的：观察多巴胺（Dopa)、去甲肾上腺素（NE）、去甲肾上腺素联合多巴酚丁胺（NE＋Dobu）对感染性休克患者胃肠道灌注的影响。方法：符合感染性休克诊断标准的13例患者经过积极的液体复苏后，随机应用血管活性药物，观察胃粘膜内pH(pHi）、胃粘膜与动脉血二氧化碳分压差（△PCO2）的变化。结果：多巴胺、去甲肾上腺素，去甲肾上腺素＋多巴酚丁胺都能提高血压，增加心排指数（CI）、体循环阻力指数（SVRI）、左室每搏功指数（LVSWI）、氧输送（DO2），与基础值比较差异有显著性意义（P＜0．05）；但对胃pHi,△PCO2的改善去甲肾上腺素＋多巴酚丁胺比单独去甲肾上腺素明显，比多巴胺更好，差异有显著性意义（P＜0．05）。结论：多巴酚丁胺和去甲肾上腺素联合即能增加CI、SVRI、LVSWI、DO2，又能改善胃pHi, △PCO2，是治疗感染性休克患者理想的血管活性药。     

Delivery dependent oxygen consumption in patients with septic shock: Daily variations,relationship with outcome and the sick-euthyroid syndrome

Delivery dependent oxygen consumption (DDOC) is observed in patients with sepsis and vital organ dysfunction, and has been related to outcome. Similarly the sick-euthyroid syndrome is associated with a high mortality. We examined the daily variations of DDOC and its relation to hormonal changes, particularly those of the thyroid. In 22 patients, 14 with septic shock and 8 post-operative controls, oxygen delivery was increased by increasing cardiac output with vasodilation by phentolamine, during a total of 207 days. DDOC varied markedly between consecutive days in individual patients with sepsis, in both survivors and non-survivors. DDOC was related to severity of illness, assessed by APACHE II score (r=0.50,p=0.017), and plasma levels of triiodothyronine (T₃),r=–0.49,p=0.011, and thyroxine (T₄),r=–0.53,p=0.012. No correlation was observed between DDOC and outcome, nor blood levels of lactate, epinephrine, norepinephrine, dopamine or cortisol. In conclusion, we observed a marked disturbance of systemic oxygen uptake autoregulation in patients with septic shock which varied during the clinical course and was related to the sick-euthyroid syndrome.With the technical assistance of J. Lopez     

Defining metabolic acidosis in patients with septic shock using Stewart approach

Purpose

The aim of this study was to define the nature of metabolic acidosis in patients with septic shock on admission to intensive care unit (ICU) using Stewart method. We also aimed to compare the ability of standard base excess (SBE), anion gap (AG), and corrected AG for albumin and lactate (AGcorr) to accurately predict the presence of unmeasured anions (UA).

Patients and Methods

Thirty consecutive patients with septic shock were prospectively included on ICU admission. Stewart equations modified by Figge were used to calculate the strong ion difference and the strong ion gap (SIG).

Results

Most patients had multiple underlying mechanisms explaining the metabolic acidosis. Unmeasured anions and hyperchloremia were present in 70% of the patients. Increased UA were present in 23% of patients with normal values of SBE and [HCO₃⁻]. In these patients, plasma [Cl⁻] was significantly lower compared with patients with low SBE and increased UA (103 [102-106.6] vs 108 [106-111] mmol/L; P = .01, respectively). Corrected AG for albumin and lactate had the best correlation with SIG (r² = 0.94; P < .0001) with good agreement (bias, 0, and precision, 1.22) and highest area under the receiver operating characteristic curve (0.995; 95% confidence interval, 0.87-1) to discriminate SIG acidosis.

Conclusions

Patients with septic shock exhibit a complex metabolic acidosis at ICU admission. High UA may be present with normal values of SBE and [HCO₃⁻] as a result of associated “relative” hypochloremic alkalosis. Corrected AG for albumin and lactate offers the most accurate bedside alternative to Stewart calculation of UA.     

脓毒性休克时大鼠全身氧供给与氧消耗关系的变化

目的：观察脓毒性休克时全身氧供给（ＤＯ２）与氧消耗（ＶＯ２）关系的变化。方法：以改良的盲肠结扎穿孔（ＣＬＰ）方法制备大鼠脓毒性休克模型，观察大鼠休克过程中ＤＯ２、ＶＯ２、氧摄取率（ＥＲＯ２）等变化。结果：ＣＬＰ后５小时已出现平均动脉压明显下降（Ｐ＜０．０５）。在休克早期，ＤＯ２即进行性下降，ＥＲＯ２出现代偿性升高，ＶＯ２维持相对不变，呈非氧供依赖关系；当ＤＯ２降至３４．６０ｍｌ·ｋｇ－１／ｍｉｎ后，ＶＯ２随ＤＯ２线性降低（ｒ＝０．７３３，Ｐ＜０．０１），即呈病理性氧供依赖关系。结论：脓毒性休克时ＤＯ２与ＶＯ２间呈双相变化关系，病理性氧供依赖的出现与组织氧摄取和氧利用功能障碍有关。     

Effect of dopexamine on hepatic metabolic activity in patients with septic shock

Hepato-splanchnic metabolic activity is seen to be related to regional blood flow and oxygen/substrate availability in patients with sepsis. Catecholamines, which may modulate metabolic activity perse, are common to stabilize hemodynamics. We studied the effect of a dopexamine-induced increase in splanchnic blood flow (Qspl) on regional metabolic rate in 10 patients with septic shock requiring norepinephrine to maintain mean arterial pressure (>60 mmHg). Splanchnic blood flow was determined using the indocyanine-green method with hepatic venous sampling. We determined the hepato-splanchnic lactate, pyruvate, alanine, and glutamine turnover and the lactate/pyruvate and ketone body ratio as well as the endogenous glucose production (EGP) using the stable isotope approach. Qspl increased from 0.86 (0.79-1.15) to 0.96 (0.92-1.33) L/min/m2, not influencing any parameter of metabolic activity. We speculate that this finding is due to altered beta-adrenoreceptor-mediated thermogenic effects due to the interplay of different beta-sympathomimetics at the receptor site.     

Enoximone in contrast to dobutamine improves hepatosplanchnic function in fluid-optimized septic shock patients

OBJECTIVE: To investigate the impact of dobutamine and enoximone on hepatosplanchnic perfusion and function in fluid-optimized septic patients. DESIGN: Prospective, randomized, double-blinded interventional study. SETTING: Intensive care unit of a university hospital. PATIENTS: Forty-eight septic shock patients were examined within 12 hrs after onset of septic shock. Patients were conventionally resuscitated, achieving an optimal pulmonary artery occlusion pressure at which the left ventricular stroke work was on the maximal plateau. Liver blood flow was estimated by venous suprahepatic catheterization using the continuous indocyanine green infusion technique. Microsomal liver function was assessed by the plasma appearance of monoethylglycinexylidide, and release of hepatic tumor necrosis factor-alpha (TNF-alpha) was measured to estimate the severity of hepatic ischemia-reperfusion syndrome. INTERVENTIONS: Patients were randomly treated with dobutamine or enoximone. Within the first 10 hrs after baseline measurements, the dosage was increased until no further increase in the left ventricular stroke work index occurred. Then, positive inotropes were kept constant throughout the study. MEASUREMENTS AND MAIN RESULTS: Measurements were performed at baseline and after 12 and 48 hrs after baseline measurements. Cardiac index, systemic oxygen delivery, systemic oxygen consumption, and liver blood flow increased significantly in both groups during treatment (p <.01) without a significant difference between groups. Fractional liver blood flow (liver blood flow/cardiac index) did not change in the enoximone group and showed a significant but only minor (median, 10%) decrease in the dobutamine group (p <.05 after 12 hrs and p <.01 after 48 hrs vs. baseline). After 12 hrs of enoximone treatment, monoethylglycinexylidide kinetics and hepatosplanchnic oxygen consumption demonstrated a significant increase (p <.05). The release of hepatic TNF-alpha after 12 hrs of dobutamine treatment was twice as high (p <.05) as during enoximone. CONCLUSION: The increase in hepatosplanchnic oxygen consumption, together with an increased lignocaine metabolism and decreased release of hepatic TNF-alpha, indicates improved hepatosplanchnic function and antiinflammatory properties after 12 hrs of enoximone treatment. Therefore, if the inflammatory response should be attenuated in high-risk patients, administration of enoximone in fluid-optimized septic shock patients may be favorable compared with dobutamine.     

Comparative haemodynamic effects of dopamine and dobutamine in septic shock

Septic shock associated with depressed myocardial function generally requires the use of catecholamine. Currently dopamine is often selected. Dobutamine is a newly developed catecholamine which has been shown to be of value in severe cardiomyopathic disease. The aim of this work was to determine the most appropriate drug by comparing haemodynamic responses to dopamine and dobutamine in 19 studies carried out in 11 patients with septic shock and heart failure. Cardiac index increased similarly with dopamine and dobutamine (33%), as did stroke volume (respectively 26.4 and 25%). Arterial pressure increased by 17% with dopamine whereas it did not significantly change with dobutamine due to reduction in vascular resistance of 19%. Dobutamine decreased filling pressure, either right (14%) or left (28%) whilst they slightly but unsignificantly increased with dopamine. Pulmonary shunting increased more with dopamine (47%) than with dobutamine (16%), but PaO₂ remained constant with both. Since septic shock is characterized by lowered arterial pressure and vasodilatation it is concluded that effects of dopamine on capacitance and resistance vessels make this drug more suitable. In addition it selectively increases renal blood flow. Nevertheless dobutamine could be appropriate, in case of very high filling pressures, severe peripheral vasoconstriction, marked pulmonary shunting and in some cases where dopamine becomes ineffective.     

Evaluation of a replenishment type oxygen consumption monitor

This paper describes the testing of a monitor (Oxyconsumeter) which uses a replenishment technique to measure oxygen consumption (VO2). Oxygen is added to the expired gas to replace the oxygen consumed by the patient. The replenishing oxygen flow equals the patients's VO2 when the mixed replenished expired oxygen fraction equals the inspired oxygen fraction. The accuracy of the Oxyconsumeter was assessed using a N2 and CO2 dilution technique. When tested over the operating range specified by the manufacturer, the bias of the Oxyconsumeter was 1.66% of reading. The reproducibility averaged 6.96% of reading. The reproducibility did not change with VO2, FIO2 or minute ventilation. The replenishment technique has the theoretical advantage that an absolute oxygen sensor calibration is not necessary and a respiratory flowmeter is not needed. It appears, from the laboratory testing, that the Oxyconsumeter has sufficient accuracy for use in the critical care setting.     

经皮氧分压监测在脓毒性休克患者中的临床应用

脓毒症和脓毒性休克是ICU患者最常见的死亡原因之一。液体治疗是治疗脓毒性休克的重要手段之一,如何进行液体治疗仍然存在很大争议,目前普遍以容量反应性来指导液体治疗。但也有学者发现,即使宏观血流动力学恢复,微循环仍可能存在障碍。休克的本质是微循环障碍,如何监测微循环状况及利用微循环监测对脓毒性休克患者进行早期诊断、病情评估,以及指导液体治疗可能是今后研究的方向。经皮氧分压（TcPO₂）监测技术是通过无创方法将皮肤表面电极加热来估测组织氧分压的技术手段。越来越多的学者研究发现TcPO₂在监测脓毒症和脓毒性休克患者局部组织灌注不足、预测患者预后、指导液体治疗等方面有重要的临床价值。因此本文对TcPO₂在脓毒性休克中的应用进行整理和总结。     

Hemodynamics and metabolic studies on septic shock in patients with acute liver failure

Backgrounds

Acute liver failure is often accompanied by hyperdynamic circulation, which is also a characteristic of septic shock. Pre-existing acute liver failure may worsen the hemodynamic impairment and prognosis in sepsis.

Aims

To evaluate the hemodynamic and metabolic characteristics and clinical outcomes of septic shock in patients with acute liver failure.

Methods

Twenty patients with acute liver failure and 19 patients without preexisting liver disease were evaluated. Systemic hemodynamics, arterial and mixed vein blood gases, arterial lactate levels, plasma renin activity, and plasma aldosterone levels were checked during the early phase of septic shock.

Results

In acute liver failure group, cardiac index (4.92 ± 1.13 vs 3.69 ± 1.06 L/min per square meter, P < .001) and oxygen delivery (604.7 ± 139.7 vs 485.4 ± 137.3 mL/min per square meter, P = .011) were significantly higher than those without preexisting liver diseases, while systemic vascular resistance index (1041.2 ± 503.3 vs 1409 ± 505.25 dyne·s/cm⁵·m²), oxygen consumption (119.1 ± 29.2 vs 162.4 ± 49.4 mL/min per square meter) and oxygen extraction ratio (20% ± 6% vs. 32% ± 8%) were significantly higher in the latter group. Furthermore, the patients with acute liver failure had higher arterial lactate (P = .026), plasma renin activity (P = .03), plasma aldosterone levels (P < .001), and intensive care unit as well as hospital mortality rates (P = .005, and 0.02 respectively).

Conclusions

In patients with acute liver failure, septic shock was characterized by an accentuated hyperdynamic circulation, hyperlactatemia and an augmented renin-angiotensin-aldosterone system activity. Pre-existing liver failure has a significant impact on the disease severity of septic shock and portends a grave prognosis.     

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     

Hepato-splanchnic metabolic effects of the stable prostacyclin analogue iloprost in patients with septic shock

OBJECTIVE: To evaluate the effects of the stable prostacyclin analogue iloprost on hepato-splanchnic blood flow, oxygen exchange and metabolism in patients with septic shock. DESIGN: Prospective clinical study. SETTING: Intensive care unit in a university clinic. PATIENTS: Eleven patients with septic shock requiring norepinephrine to maintain mean arterial pressure above 70 mmHg. INTERVENTIONS: Iloprost was incrementally infused to increase cardiac index by 15%. MEASUREMENTS AND MAIN RESULTS: Splanchnic blood flow (Qspl) was measured using the steady-state indocyanine-green infusion technique and endogenous glucose production rate (EGP) using a stable isotope approach. Systemic and splanchnic oxygen consumption (VO2), the hepato-splanchnic uptake rates of the glucose precursors lactate, pyruvate, alanine and glutamine, the hepatic venous redox state and gastric mucosal-arterial PCO2 gradients were determined. After a baseline measurement, iloprost infusion was started. After 90 min all measurements were repeated and a third measurement was obtained after another 90 min following iloprost withdrawal. Qspl (baseline I: 0.82/0.75-1.08 l x min x m2; iloprost: 0.94/0.88-1.29 l x min x m2; baseline II: 0.87/0.74-1.09 l x min x m2) and splanchnic oxygen delivery (baseline I: 122/103-166 ml x min x m2; iloprost: 134/117-203 ml x min x m2; baseline II: 130/98-158 ml x min x m2) significantly increased. While systemic VO2 significantly increased (baseline I: 139/131-142 ml x min x m2; iloprost: 147/136-164 ml x min x m2; baseline II: 143/133-154 ml x min x m2) splanchnic VO2 increased in 9 of 11 patients which, however, did not reach statistical significance. EGP significantly decreased (baseline I: 23/16-26 micromol x kg x min; iloprost: 16/14-21 micromol x kg x min; baseline II: 18/12-20 micromol x kg x min), whereas all other parameters of energy metabolism remained unchanged. CONCLUSION: In patients with septic shock an iloprost-induced increase in cardiac index increased splanchnic blood flow and shifted oxygen utilization from the energy requiring de novo glucose production rate to other oxygen-demanding metabolic pathways.     

Effects of high-volume hemofiltration on alveolar-arterial oxygen exchange in patients with refractory septic shock

BACKGROUND: High-volume hemofiltration (HVHF) is technically possible in severe acute pancreatitis (SAP) patients complicated with multiple organ dysfunction syndrome (MODS). Continuous HVHF is expected to become a beneficial adjunct therapy for SAP complicated with MODS. In this study, we aimed to explore the effects of fluid resuscitation and HVHF on alveolar- arterial oxygen exchange, the Acute Physiology and Chronic Health Evaluation II (APACHE II) score in patients with refractory septic shock.METHODS: A total of 89 refractory septic shock patients, who were admitted to ICU, the Provincial Hospital affiliated to Shandong University from August 2006 to December 2009, were enrolled in this retrospective study. The patients were randomly divided into two groups: fluid resuscitation (group A, n=41), and fluid resuscitation plus high-volume hemofiltration (group B, n=48). The levels of O₂ content of central venous blood (C_cvO₂), arterial oxygen content (C_aO₂), alveolar-arterial oxygen pressure difference P_(A-a)DO₂, ratio of arterial oxygen pressure/alveolar oxygen pressure (P_aO₂/P_AO₂), respiratory index (RI) and oxygenation index (OI) were determined. The oxygen exchange levels of the two groups were examined based on the arterial blood gas analysis at different times (0, 24, 72 hours and 7 days of treatment) in the two groups. The APACHE II score was calculated before and after 7-day treatment in the two groups.RESULTS: The levels of C_cvO₂, C_aO₂ on day 7 in group A were significantly lower than those in group B (C_cvO₂: 0.60±0.24 vs. 0.72±0.28, P<0.05; CaO₂: 0.84±0.43 vs. 0.94±0.46, P<0.05). The level of oxygen extraction rate (O₂ER) in group A on the 7th day was significantly higher than that in group B ( 28.7±2.4 vs. 21.7±3.4, P<0.01). The levels of P_(A-a)DO₂ and RI in group B on the 7th day were significantly lower than those in group A. The levels of P_aO₂/P_AO₂ and OI in group B on 7th day were significantly higher than those in group A (P<0.05 or P<0.01). The APACHE II score in the two groups reduced gradually after 7-day treatment, and the APACHE II score on the 7th day in group B was significantly lower than that in group A (8.2±3.8 vs. 17.2±6.8, P<0.01).CONCLUSION: HVHF combined with fluid resuscitation can improve alveolar- arterial-oxygen exchange, decrease the APACHE II score in patients with refractory septic shock, and thus it increases the survival rate of patients.