Renal effects of hypotensive anaesthesia in combination with acute normovolaemic haemodilution with hydroxyethyl starch 130/0.4 or isotonic saline

BACKGROUND: Hypotensive anaesthesia (HA) and acute normovolaemic haemodilution (ANH) are used separately to decrease per-operative blood loss. Reducing blood viscosity by adding ANH to HA may appear profitable in a situation with lowered perfusion pressure and concern about organ ischemia. The aim of this study was to clarify the influence of HA in combination with ANH using crystalloid or colloid as replacement fluid on renal function. METHODS: Hypotensive anaesthesia was induced in 11 patients referred to major spine surgery using sevoflurane in combination with fentanyl/remifentanil. Acute normovolaemic haemodilution was carried out by drawing venous blood into standard blood bags and replacing it by isotonic saline 0.9% (Group S) or HES 130/0.4 (Group V). Renal function was evaluated before, during and up to 8 h after hypotension as the glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) by means of 51Cr-EDTA and 125I-Hippuran clearances. RESULTS: Lowering mean arterial blood pressure decreased GFR and ERPF in both groups. During hypotension ERPF was lower in Group S (n = 5) than Group V (n = 6). Renal function was normalized postoperatively. We found a positive but non-significant correlation between the relative GFR change and the duration of hypotension. CONCLUSION: In conclusion, our study demonstrated that renal function, assessed by GFR and ERPF, is transiently reduced during the combination of hypotensive anaesthesia and acute normovolaemic haemodilution. A colloid-based fluid regime (HES 130/0.4) used for haemodilution may preserve renal function to a greater extent than a crystalloid-based regime (0.9% saline).     

Colloids decrease clot propagation and strength: role of factor XIII-fibrin polymer and thrombin-fibrinogen interactions

Colloid-mediated hypocoagulability is clinically important, but the mechanisms responsible for coagulopathy have been incompletely defined. Thus, my goal was to elucidate how colloids decrease plasma coagulation function. Plasma was diluted 0% or 40% with 0.9% NaCl, three different hydroxyethyl starches (HES, mean molecular weight 450, 220 or 130 kDa), or 5% human albumin. Samples (n=6 per condition) were activated with celite, and diluted samples had either no additions or addition of fibrinogen (FI), thrombin (FIIa) or activated Factor XIII (FXIIIa) to restore protein function to prediluted values. Thrombelastographic variables measured included clot propagation (angle, alpha), and clot strength (amplitude, A; or shear elastic modulus, G). Dilution with 0.9% NaCl significantly decreased alpha, A and G-values compared to undiluted samples. Supplementation with FI, but not FIIa or FXIIIa, resulted in 0.9% NaCl-diluted thrombelastographic variable values not different from those of undiluted samples. FI supplementation of HES 450, HES 220, HES 130 and albumin-diluted samples only partially restored alpha, A and G-values compared to undiluted samples. FIIa addition only improved clot propagation and strength in albumin-diluted samples. FXIIIa supplementation improved propagation in samples diluted with HES 450, HES 220 and albumin, and clot strength improved in HES 450 and albumin-diluted plasma. Considered as a whole, these data support compromise of FIIa-FI and FXIIIa--fibrin polymer interactions as the mechanisms by which colloids compromise plasma coagulation. Investigation to determine if clinical enhancement of FXIII activity and/or FI concentration (e.g. fresh-frozen plasma, cryoprecipitate) can attenuate colloid-mediated decreases in hemostasis is warranted.     

Molecular weight of hydroxyethyl starch: is there an effect on blood coagulation and pharmacokinetics?

Background. The development of hydroxyethyl starches (HES) withlow impact on blood coagulation but higher volume effect comparedwith the currently used HES solutions is of clinical interest.We hypothesized that high molecular weight, low-substitutedHES might possess these properties. Methods. Thirty pigs were infused with three different HES solutions(20 ml kg^–1) with the same degree of molar substitution(0.42) but different molecular weights (130, 500 and 900 kDa).Serial blood samples were taken over 24 h and blood coagulationwas assessed by Thromboelastograph® analysis and analysisof plasma coagulation. In addition, plasma concentration andin vivo molecular weight were determined and pharmacokineticdata were computed based on a two-compartment model. Results. Thromboelastograph analysis and plasma coagulationtests did not reveal a more pronounced alteration of blood coagulationwith HES 500 and HES 900 compared with HES 130. In contrast,HES 500 and HES 900 had a greater area under the plasma concentration–timecurve [1542 (142) g min litre^–1, P<0.001, 1701 (321)g min litre^–1, P<0.001] than HES 130 [1156 (223) gmin litre^–1] and alpha half life (     

Effectivity of laser-induced thermotherapy: in vivo comparison of arterial microembolization and complete hepatic inflow occlusion

BACKGROUND AND OBJECTIVES: Laser-induced thermotherapy (LITT) is a promising method for local treatment of liver metastases. The aim of this study was to compare the effect of LITT on lesion size when combined with hepatic arterial microembolization or complete hepatic blood flow occlusion. STUDY DESIGN/MATERIALS AND METHODS: In a porcine liver model, LITT (30 W 15 minutes) was performed with either normal (n = 12), partially interrupted (arterial microembolization via a hepatic artery catheter n = 12) or completely interrupted hepatic perfusion (Pringle's maneuver, n = 12). LITT lesions were macro- and microscopically assessed after liver dissection. RESULTS: Hepatic inflow occlusion led to a fourfold increase in lesion volume after arterial microembolization and a ninefold increase after complete interruption (6.3. cm3 vs. 27.1 cm3 vs. 58.8 cm3, P < 0.01). CONCLUSIONS: Interrupting hepatic perfusion significantly increases lesion volumes in LITT. This beneficial effect can also be achieved in the percutaneous application mode by LITT combined with arterial microembolization via a hepatic artery catheter.     

Reactive Extrusion of Starch‐Polyacrylamide Graft Copolymers: Effects of Monomer/Starch Ratio and Moisture Content

Summary: The effects of monomer/starch feed ratios and moisture content during reactive extrusion of starch‐polyacrylamide graft copolymers were investigated. Acrylamide/starch ratios ranged from 0.20 to 1.87 at 50% moisture content, while moisture content was increased from 45 to 75% with an acrylamide/starch ratio of 0.33. Average conversion was 86.6% (±3.5%), independent of monomer content, at acrylamide/starch ratios of 0.77 and less. Conversion increased to approximately 95% when the acrylamide/starch ratio exceeded unity. Molecular weight of grafted polyacrylamide increased as the acrylamide/starch ratio increased. Graft efficiency was constant at approximately 75% for monomer/starch ratios of 0.77 or less, and decreased to 52.3% as the monomer/starch ratio increased to 1.87. Higher acrylamide/starch ratios gave more frequent grafts of higher molecular weight. As moisture content decreased from 75 to 45%, conversion and graft content increased from 78 and 14% to 97 and 23%, respectively. Lower moisture content gave fewer grafts of higher molecular weight. Ungrafted polyacrylamide homopolymer increased with monomer/starch ratio and moisture content. These results indicate that graft copolymer properties can be controlled through the monomer/starch ratio and moisture content during reactive extrusion.

Molecular weight distributions of grafted polyacrylamide at different moisture contents during extrusion: A) 75%; B) 65%; C) 55%; D) 45%.     

Predictable reduction of intracranial hypertension with hypertonic saline hydroxyethyl starch: a prospective clinical trial in critically ill patients with subarachnoid haemorrhage

BACKGROUND: After head trauma, hypertonic saline lowers intracranial pressure (ICP) and preserves or increases cerebral perfusion pressure (CPP). Hypertonic saline has not been studied in patients with increased ICP due to subarachnoid haemorrhage (SAH). The aim of this study was to evaluate the effects on elevated ICP and on CPP in patients critically ill from SAH. METHODS: Critically ill SAH-patients needing urgent treatment for an elevated ICP, but otherwise stable, were included in this study. We infused 7.2% saline in 6% hydroxyethyl starch (HyperHAES((R)) Fresenius Kabi AG, Bad Homburg v.d.h., Germany) 2 ml kg(-1) during 20 min in 10 episodes of ICP > 20 mmHg in seven patients with SAH. Our primary outcome variables were changes in ICP and CPP during and for 3 h after this infusion. RESULTS: All interventions resulted in decreased ICP and elevation of CPP. The mean value for maximum ICP decrease in percent of baseline was 58% (range 43-83%, P = 0.002), which occurred at mean 40 min (range 25-90 min) after start of infusion. The mean percent peak increase in CPP was 26% (range 16-32%, P = 0.002). After 210 min, ICP was 35% lower than baseline (range 19-39%, P = 0.008). Serum sodium increase was mean 6.6 mmol l(-1) (range 5-9 mmol l(-1)) 30 min after start of infusion. CONCLUSIONS: 7.2% saline in 6% hydroxyethyl starch is an effective and safe therapy for intracranial hypertension after SAH. We demonstrate that an infusion of 2 ml kg(-1) during 20 min has a predictable and clinically significant beneficial effect on ICP and CPP. The effect was still present 3 h after end of infusion. Rebound ICP-increase was not observed within 3 h.     

A randomized,controlled study of fluid management in infants and toddlers during surgery: hydroxyethyl starch 6% (HES 70/0.5) vs lactated Ringer's solution

BACKGROUND: Volume replacement with hydroxyethyl starch (HES), a synthetic colloid, is widely accepted in adults, but only few data exist regarding its use in children. The aim of this study was to assess the effect of a low molecular weight HES solution (HES 70/0.5) compared with lactated Ringer's solution (LR) on haemoglobin levels as an indirect measure of plasma expansion in infants and toddlers, and its perioperative safety. METHODS: Sixty-four patients, aged 1-38 months, were allocated randomly to receive 20 ml x kg-1 body weight of either HES 70/0.5 or LR during the first hour of urological surgery lasting >2 h. Thereafter, only LR was infused to maintain haemodynamic stability. Intraoperative blood loss and administered fluid volumes were analysed. Haemoglobin levels were determined perioperatively and intraoperatively at completion of volume loading. Changes in body weight and the incidence of postoperative oedema were assessed 24 and 48 h after surgery. For the safety analysis, patients were monitored for 72 h. RESULTS: Intraoperative haemoglobin levels decreased significantly more with HES 70/0.5 (30 +/- 10 g.l-1) compared with LR (21 +/- 12 g.l-1) (P < 0.01). The overall administered fluid volumes during surgery did not differ between groups. The postoperative changes in body weight and incidence of postoperative oedema did not differ between groups. No anaphylactoid reactions, pruritus or adverse effects were observed during the study period. CONCLUSIONS: A larger decrease in haemoglobin levels in infants and toddlers after HES 70/0.5 (20 ml.kg-1) compared with LR indicates a more effective plasma expansion. HES might be considered as a volume expander in the paediatric population.     

卵巢癌细胞减灭术中应用羟乙基淀粉溶液对病人内脏氧合的影响

目的　研究在卵巢癌细胞减灭术中用中分子量羟乙基淀粉溶液替代失血对病人内脏氧合的影响。方法　对筛选的 42例卵巢癌细胞减灭术的病人在术中失血量为估计血容量的 10 %～2 0 %时 ,将病人按随机表顺序分为乳酸林格氏液组 (LRS组 ,2 2例 ) ,或 6 %中分子量羟乙基淀粉组(HES组 ,2 0例 )。LRS组输入 3倍于估计失血量 (EBL)的LRS ,HES组输入与EBL等容量的HES。组织氧合程度是通过测定胃张力计参数间接评估的 ,包括胃粘膜CO2 分压 (PsCO2 )、动脉血CO2 分压(PaCO2 )差值 (Ps aCO2 间隙 )、胃粘膜pH值 (pHi)及动脉血乳酸浓度。Ps aCO2 间隙、胃粘膜pHi和动脉血乳酸浓度测定时间点为全麻诱导后 30min (基础值 ) ,切皮后 1h、2h和术终。结果　手术结束时 ,HES组病人Ps aCO2 间隙为 8 7mmHg± 1 6mmHg ,LRS组为 18 74mmHg± 4 4mmHg,两组比较P <0 0 1;而胃粘膜pHiHES组为 7 30± 0 0 5 ,LRS组为 7 2 1± 0 0 7,两组比较P <0 0 1。两组病人动脉血乳酸浓度差异无显著意义。结论　对于失血较多的大手术病人 ,用中分子量羟乙基淀粉行容量复苏可改善内脏血流灌注和组织氧合。     

羟乙基淀粉溶液术前扩容对围术期冠心病患者血小板活化的影响

 【目的】 观察两种羟乙基淀粉（HES）溶液术前扩容对冠心病患者围术期血小板膜糖蛋白Ⅱb/Ⅲa（GPⅡb /Ⅲa）、GMP-140表达的影响。【方法】 全麻下接受胆囊切除术的冠心病患者45例，心功能Ⅰ-Ⅱ级，随机分为3组（n＝15）：术前以10 ml·kg-1剂量于30 min内输注HES200/0．5（组Ⅰ）、HES130/0．4（组Ⅱ）和乳酸钠林格氏（RL）溶液（组Ⅲ）。抽取静脉血，采用流式细胞仪检测麻醉前（T0）、扩容结束后即刻（T1）、扩容结束后1h（T2）、手术结束后2 h（T3）时 GPⅡb/Ⅲa与GMP-140的表达。【结果】 组ⅠT1 、T2 和 T3时GPⅡb/Ⅲa表达较T0降低；与组Ⅱ、组Ⅲ比较，组Ⅰ扩容后的GPⅡb/Ⅲa表达降低（P<0．05）；组ⅡT1时GPⅡb/Ⅲa表达较T0降低（P<0．05）；与组Ⅲ比较，组ⅡT1 和 T3时GPⅡb/Ⅲa表达降低（P<0．05）；组ⅢT3时GPⅡb/Ⅲa表达较T0增加；组ⅠT1、T2 和 T3时GMP-140表达较T0降低（P<0．05）；与组Ⅱ、组Ⅲ比较，组Ⅰ扩容后的GMP-140表达降低（P<0．05）；与组Ⅲ比较，组ⅡT2和 T3时GMP-140表达降低（P<0．05）；组ⅢT2和T3时GMP-140表达较T0增加（P<0．05）。【结论】 术前采用HES溶液扩容能抑制血小板GPⅡb/Ⅲa复合物与GMP-140表达，其中HES200/0．5作用较HES130/0．4明显。此作用对避免不稳定斑块处血小板的进一步积聚，防止围术期冠心病患者病情恶化可能有一定的作用。     

钛酸四丁酯增韧改性聚乳酸/淀粉共混材料

制备了钛酸四丁酯[Ti(OBu)4]增韧改性的聚乳酸(PLA)/淀粉共混材料,测试了材料的加工流变性能、力学性能、共混形态、结晶性能及疏水性能和降解性能。结果表明:当mTi(OBu)4∶mPLA=0.20时,共混材料的冲击强度提高了40.9%,而弯曲强度下降了59.2%;FT-IR和SEM显示钛酸四丁酯的化学架桥作用增加了共混材料中聚乳酸与淀粉的相容,其吸水率随钛酸四丁酯含量的增加而减少,掩埋150 d后质量下降5%~8%。