End-point temperature of rewarming after hypothermic cardiopulmonary bypass in pediatric patients

In an attempt to find an adequate end-point rewarming temperature after hypothermic cardiopulmonary bypass (CPB), 50 pediatric patients who underwent cardiac surgery were randomly assigned for the end-point rectal rewarming temperature at either 35.5 (Group 1) or 37.0 degrees C (Group 2). The patients' rectal temperature, with heart rate and blood pressure, was measured 0.5, 1.0, 4.0, 8.0, and 16.0 h after the arrival in the intensive care unit. For all patients, nonpulsatile perfusion with a roller pump and a membrane or bubble oxygenator was used for oxygenation. Age, sex, body surface area, total bypass time, and rewarming time were comparable in both groups. No afterdrop and no statistical differences in the rectal temperatures between the two groups were observed. Also, no statistical differences were observed between the two groups with respect to the heart rate and blood pressure. No shivering was noted in all patients. In conclusion, with the restoration of rectal temperature above 35.5 degrees C at the end of CPB in pediatric patients, the present study found no afterdrop.     

Pharmacokinetics of ketamine during hypothermic cardiopulmonary bypass in cardiac patients

Cardiopulmonary bypass (CPB) makes prediction of any drug concentration diffcult because both hypothermia and hemodilution can alter the pharmacokinetics of the drug. Eleven patients undergoing cardiac surgery under CPB were anesthetized with continuous infusion of ketamine combined with intermittent administration of droperidol and fentanyl. The infusion rate of ketamine was 2 mg·kg⁻¹·hr⁻¹ following a bolus administration of 1.5 mg·kg⁻¹ for the induction of anesthesia. Blood concentrations of ketamine and its main metabolite, norketamine, were measured at 0, 30, and 60 min after the start of and the end of CPB, and 0, 1, 2, and 24 h after the cessation of ketamine infusion. Hypothermia increased blood ketamine levels during CPB, but the norketamine levels did not change. Although acute hemodilution would decrease blood ketamine levels, their levels were already significantly increased at 30 min after CPB. Hypothermic factors have a more kinetically important role during CPB than hemodilution. Increases in blood norketamine levels following rewarming indicate that hypothermia could impair ketamine metabolism in the liver. Further increase in the plasma concentration of ketamine until 30 min after the end of CPB might be due to blood transfusion containing ketamine from the CPB reservoir.     

全主动脉弓置换术患者体外循环深低温时高氧血气管理的效果

目的研究全主动脉弓置换术中患者体外循环（CPB）深低温时高氧血气管理的临床效果。方法32例拟行全主动脉弓置换术患者随机分为常规血气管理组（常规组，16例）和高氧血气管理组（高氧组，16例）。CPB术中分别采用常规血气管理及高氧血气管理方法。分别在切皮前、CPB15min、选择性脑灌注（SCP）10min、降主动脉开放5min、左锁骨下动脉开放5min、左颈总动脉开放5min、无名动脉开放5min、鼻咽温复温至35℃、CPB停止10min经颈静脉球及氧合器动脉端取血进行血气分析，检测颈静脉球血氧饱和度（SjvO2）、血氧分压（PjvO2）及PaO2。观察术后机械通气时间、苏醒时间、ICU停留时间。手术前后进行神经系统物理检查、颅脑计算机体层摄影等检查。结果经调整混杂因子的多元线性回归分析，高氧组深低温期间PaO2与PjvO2呈显著独立正相关（B=0．129，SE=0．045，P〈0．05）。高氧组有2例（12．5％），常规组有3例（18．75％）出现短暂性神经功能异常；与常规组比较，高氧组CPB中SjvO2、PjvO2升高，术后苏醒时间、ICU停留时间缩短。结论全主动脉弓替换术中CPB深低温期间采用高氧血气管理方法可提高溶解氧的供给，增加氧储备，临床预后较好。     

Changes in body temperature during profound hypothermic cardiopulmonary bypass in adult patients undergoing aortic arch reconstruction

Purpose Our aim was to characterize changes in body temperatures during profound hypothermic cardiopulmonary bypass (CPB) conducted with the sternum opened.Methods In ten adult patients who underwent profound hypothermic (20°C) CPB for aortic arch reconstruction, pulmonary arterial temperature (PAT), nasopharyngeal temperature (NPT), forehead deep-tissue temperature (FHT), and urinary bladder temperature (UBT) were recorded every 1min throughout the surgery. In addition, the CPB venous line temperature (CPBT), a reasonable indicator of mixed venous blood temperature during CPB and believed to best reflect core temperature during stabilized hypothermia on CPB, was recorded during the period of total CPB.Results PAT began to change immediately after the start of cooling or rewarming, closely matching the CPBT (r = 0.98). During either situation, the other four temperatures lagged behind PAT (P 0.05); however, NPT followed PAT more closely than the other three temperatures (P 0.05). During stabilized hypothermia, PAT, NPT, and FHT, but not UBT, closely matched the CPBT, with gradients of less than 0.5°C.Conclusion During induction of profound hypothermia and its reversal on total CPB with the heart in situ, a PA catheter thermistor, presumably because of its placement immediately behind the superior vena cava, would provide a reliable measure of the mixed venous blood temperature. During stabilized profound hypothermia, PAT, NPT, and FHT, but not UBT, serve as a reliable index of core temperature.This work was presented, in part, at the 50th annual meeting of the Japanese Society of Anesthesiologists, Yokohama, May 29–31, 2003, and at the annual meeting of the American Society of Anesthesiologists, San Francisco, USA, October 11–15, 2003.     

婴幼儿体外循环对红细胞内钙离子浓度的影响

目的 通过比较先天性心脏病患儿体外循环(cardiepulmonary bypass,CPB)过程中红细胞内外钙离子浓度的变化,探讨CPB对红细胞形态和功能的影响.方法 分别于CPB前、中、后抽取26例先天性心脏病患儿的中心静脉血检测血浆游离钙离子浓度,同时采用Fluo-3-AM测定红细胞内的钙离子浓度.结果 CPB中血浆钙离子浓度由CPB前的(1.24±0.06)mmol/L降低至(0.99±0.05)mmol/L,CPB后钙离子浓度又恢复至(1.28±0.08)mmol/L;CPB过程中红细胞内钙离子浓度则维持了相对稳定[CPB前(138±72)nmol/L;CPB中(145±70)nmol/L;CPB后(115±83)nmol/L].结论 CPB期间红细胞内钙离子浓度无显著变化.     

Comparison of parameters for detection of splanchnic hypoxia in children undergoing cardiopulmonary bypass with pulsatile versus nonpulsatile normothermia or hypothermia during congenital heart surgeries

The aim of this study is to evaluate gastric mucosal oxygenation together with whole-body oxygen changes in infants undergoing congenital heart surgery with cardiopulmonary bypass (CPB) procedure and the use of either pulsatile or nonpulsatile mode of perfusion with normothermia and pulsatile or nonpulsatile moderate hypothermia. Sixty infants undergoing congenital cardiac surgery were randomized into four groups as: nonpulsatile normothermia CPB (NNCPB, n = 15), pulsatile normothermia CPB (PNCPB, n = 15), nonpulsatile moderate hypothermia CPB (NHCPB, n = 15), and pulsatile moderate hypothermia CPB (PHCPB, n = 15) groups. In NNCPB and PNCPB groups, mild hypothermia was used (35°C), whereas in NHCPB and PHCPB groups, moderate hypothermia (28°C) was used. Gastric intramucosal pH (pHi), whole-body oxygen delivery (DO(2)) and consumption (VO(2)), and whole-body oxygen extraction fraction were measured at sequential time points intraoperatively and up to 2 h postoperatively. The measurement of continuous tonometry data was collected at desired intervals. The values of DO(2), VO(2), and whole-body oxygen extraction fraction were not different between groups before CPB and during CPB, whereas the PNCPB group showed higher values of DO(2), VO(2), and whole-body oxygen extraction fraction compared to the other groups at the measurement levels of 20 and 60 min after aortic cross clamp, end of CPB, and 2 h after CPB (P < 0.0001). Between groups, no difference was observed for pHi, lactate, and cardiac index values (P > 0.05). This study shows that the use of normothermic pulsatile perfusion (35°C) provides better gastric mucosal oxygenation as compared to other perfusion strategies in neonates and infants undergoing congenital heart surgery with CPB procedures.     

Pulsatile flow improves cerebral blood flow in pediatric cardiopulmonary bypass

The objective of this study was to evaluate the effect of pulsatile flow on cerebral blood flow (CBF) in infants with the use of a mild hypothermic cardiopulmonary bypass (CPB). Thirty infants scheduled for open heart surgery were randomized to the pulsatile group (Group P, n = 15) and nonpulsatile group (Group NP, n = 15). In Group P, pulsatile perfusion was applied during the aortic cross‐clamping period, whereas nonpulsatile perfusion was used in Group NP. The systolic peak velocity (Vs), the end of diastolic velocity (Vd), the mean velocity (Vm), and the pulsatility index (PI) and the resistance index (RI) of the middle cerebral artery were measured by a transcranial Doppler (TCD) ultrasound after anesthesia (T1; baseline), at the beginning of CPB (T2), 10 min after aortic cross‐clamping (T3), 3 min after declamping (T4), at the cessation of CPB (T5), and at the end of the operation (T6). During T3 and T4, the Vs in Group P was significantly higher than in Group NP. However, there were no statistically significant differences between Vd and Vm. The PI and RI in Group P were also higher than those in Group NP (both P < 0.05). During T5, Vd and Vm were higher in Group P (P < 0.05), whereas there was no difference in Vs. Additionally, PI and RI in Group P were significantly lower than those in Group NP (P < 0.05). However, there was no difference during T6. Pulsatile perfusion may increase CBF and decrease cerebral vascular resistance in the early period after mild hypothermic CPB.     

Fibrinolysis in pediatric patients undergoing cardiopulmonary bypass

Thromboelastographic evaluation of the influence of fibrinolysis on blood loss and blood product transfusions in children during cardiac surgery. Prospective study. University-affiliated, pediatric medical center. Two hundred seventy-eight consecutive children undergoing cardiac surgery. Blood sampling for coagulation tests, including native and protamine-modified thromboelastography. Blood coagulation tests were measured before, during, and after cardiopulmonary bypass (CPB). Demographic data, perioperative blood loss, and blood product transfusions were prospectively recorded. Fibrinolysis was defined as thromboelastography of A30/MA less than 0.85 (MA, maximum amplitude; A30, amplitude 30 minutes after MA) and was noted in 3% of children pre-CPB, 16% during CPB, and 3% post-CPB. Fibrinolysis before CPB was associated with poor cardiac output. Fibrinolysis during CPB occurred in young children (aged 350 ± 836 days) undergoing complex surgery with prolonged CPB (119 ± 48.8 minutes) and deep hypothermia (25.6°C ± 4.7°C). These patients received blood products after CPB and were not fibrinolytic after transfusion. They incurred similar blood loss (in mL/kg) and received similar volumes of blood products (mL/kg) as age-matched and surgery-matched patients without fibrinolysis. A group of children at risk for fibrinolysis during CPB was identified. However, fibrinolysis during CPB did not influence blood loss or the total volume of blood products transfused.     

Propofol and hypothermic cardiopulmonary bypass

The effects of propofol during low flow (1.6 l.min-1.m-2) hypothermic (27-29 degrees C) cardiopulmonary bypass on systemic haemodynamic and metabolic variables were studied in 20 patients in a parallel group comparison. Patients in the control group underwent two consecutive control periods, whereas those in the propofol group underwent a control period followed by a 'propofol' period during which they received an intravenous bolus of propofol 5 mg.kg-1 followed by an infusion at a rate of 20 mg.kg-1.h-1. Haemodynamic and metabolic variables were measured at the end of each period. The propofol group showed a significant reduction in both systemic vascular resistance (p less than 0.001) and systemic oxygen uptake (p less than 0.05). There was a small but significant fall in lactate in the control group (p less than 0.02); however, there was no significant change in the propofol group. These findings could indicate impaired tissue perfusion, although they more likely indicate systemic metabolic depression with washout of lactate from previously hypoperfused tissues.     

Effects of mild hypothermic cardiopulmonary bypass on blood viscoelasticity in coronary artery bypass grafting patients

The purpose of this study was to determine the changes in blood viscoelasticity during and after coronary artery bypass grafting (CABG) and to identify correlations between blood viscoelasticity and patients' age, duration of cardiopulmonary bypass (CPB), and cross-clamp time. After Institutional Review Board approvals, patients (n = 10) who were subjected to mild hypothermic CPB were included in this study. Viscosity and elasticity were measured at strains of 0.2, 1, and 5 using a Vilastic-3 Viscoelasticity Analyzer. Arterial blood samples were collected pre-CPB, on normothermic CPB, hypothermic CPB, after rewarming, and after CPB. Viscosity and elasticity at strains of 0.2 and 1 were altered significantly during and after CPB compared to the pre-CPB (p < 0.01). In particular, elasticity of blood was diminished during normothermic bypass and could not be recovered after CPB (p < 0.01). Although there were strong correlations between blood viscoelasticity, duration of CPB, and cross-clamp time on normothermic CPB, only the patients' age showed a positive correlation between viscosity (r = 0.61, p = 0.05), and elasticity (r = 0.89, p < 0.001) after CPB. These results suggest that mild hypothermic CPB alters the blood viscoelasticity during and after CABG.     

Spectral analysis of the EEG during hypothermic cardiopulmonary bypass

In 39 patients undergoing aorto-coronary-bypass grafting, spectral analysis of the EEG (compressed spectral array: CSA) and calculation of spectral edge frequency (SEF) were performed. The effects of different temperatures and of perfusion pressure (PP) were analyzed. Predictable patterns were observed. During cooling on cardiopulmonary bypass (CPB), linear regression analysis revealed a close correlation between SEF and tympanic membrane (Tty) or nasopharyngeal temperature (Tnp). During rewarming, a nonlinear correlation between SEF and Tty or Tnp was found. Rectal temperature as well as blood temperature in the arterial or venous line of the oxygenator seemed to be less useful. The independence of SEF and PP was demonstrated during the whole procedure. At the onset of CPB, after correction of the aortic clamp for performance of the aortic anastomosis and after removal of the aortic clamp, bilateral EEG slowing of varying duration occurred in 20 patients. Comparison of mean SEF before and after CPB revealed a difference of about 5 Hz. In no patient were major neurological abnormalities observed postoperatively.     

胸主动脉瘤手术中中浅低温停循环加顺行性脑灌注技术的应用

目的 评价中浅低温停循环加脑灌注技术用于Ⅰ型夹层动脉瘤手术的临床效果.方法 2007年2月至2009年8月行主动脉弓部置换术60例,按照开始停循环的最低温度分为深度低温组(DH,32例;鼻咽温18～20℃)和中浅低温组(MH,28例;鼻咽温23～25℃).观察两组患者手术及其临床预后.结果 住院病死率3.33%(2/60例),每组各有1例死于多器官功能衰竭;开始选择性脑灌注(ASCP)时MH组的鼻咽温和直肠温度[(23.8±1.9)℃和(26.6 ±2.4)℃]明显高于DH组[(19.7±3.2℃和(22.5±2.2)℃],差异有统计学意义(P<0.05).两组ASCP时间(29.4±9.3)min对(32.9±13.4)min,差异尢统计学意义(P>0.05).MH组患者的复温时间较短,(65.00±13.9)min对(90.3±27.2)min;体外循环转机时间较短,(142.8±34.2)min对(194.1±42.0)min,差异均有统计学意义(P<0.05).两组患者术后无永久性神经系统并发症(PND),暂时性神经系统并发症(TND)的发生率为6.67%(4/60例),其中MH组为7.14%(2/28例),DH组为6.25%(2/32例),差异无统计学意义(P>0.05).术后呼吸机辅助通气时间、肾脏功能衰竭发生率、监护室停留时间和住院时间差异无统计学意义(P>0.05).结论 中浅低温加选择性脑灌注用于Ⅰ型夹层动脉瘤手术可以缩短体外循环转机时间,未增加患者术后神经系统并发症.

Abstract：

Objective To compare the effects of hypothermic arrest circulation ( HAC) with moderate or deep hypothermic antegrade selective cerebral perfusion ( ASCP) technique in patients with DeBake type Ⅰ aortic dissection or aortic arch aneurysm undergoing total aortic arch replacement. Methods Between Feb. 2007 and Aug. 2009, 60 patients who underwent aortic arch replacement using HAC + SCP technique. Patients were divided into two groups according to the lowest nasopharyngeal temperature: moderate hypothermia (18 - 20℃) (group MH, n = 28), and deep hypothermia (23 -25 ℃) (group DH,n=32). The clinical and neurological outcomes were observed. Results The overall in-hospital mortality was 3. 33% (2/60) ; In-hospital mortality was 3. 6% in the MH group, while3.1% in the DH group. There were no significant differences regarding to preoperative the patients' character parameters in both groups. At the beginning of ASCP, the nasopharyngeal and rectal temperatures were significantly higher in group MH[MH group (23.8 ± 1. 9 ) ℃ ( 26. 6 ± 2. 4 ) ℃ vs. DH group group (29.4 ±9.3) min vs. DH group(32.9 ± 13.4) min]. The rewarming time and CPB time were significantly shorter in MH group[(65.0±13.9) min vs. (90.3 ±27.2) min; (142.8 ±34.2) min vs. (194.1 ±42.0) min, P <0. 05]. Temporary neurologic deficits occurred in four patients (6. 67% ) without significant differences between two groups ( MH group 7.14% vs. DH group 6. 25% ). No patient suffered from permanent neurologic dysfunction. There were no significant differences between two groups in other parameters including intubation time, kidney insufficiency, the stay times in ICU and hospital. Conclusion Our results demonstrate that moderate HCA + ASCP technique is a safe strategy for the treatment of patients who require conventional total arch replacement with individual arch-vessel reconstruction. Shorter CPB time in patients with moderate HCA + ASCP did not increase any other postoperative adverse effects.     

应急体外循环的临床应用

目的 探讨应急体外循环（ＥＣＰＢ）在抢救心脏或非心脏危重病人中的意义和作用。方法 心脏病人以动脉－静脉转流法,非心脏病人则采用静脉－－静脉转流法。结果 ＥＣＰＢ占同期体外循环手术３．８５％（３３／８５７）。心脏手术ＥＣＰＢ２７例,成功１９例,死亡８例;非心脏手术６例,均抢救成功。结论 在某些紧急情况下采用ＥＣＰＢ可挽救以往认为无法抢救的重危病人的生命或减少后遗症、并发症。     

Oxygenator exhaust capnography for prediction of arterial carbon dioxide tension during hypothermic cardiopulmonary bypass

Continuous monitoring and control of arterial carbon dioxide tension (P(a)CO2) during cardiopulmonary bypass (CPB) is essential. A reliable, accurate, and inexpensive system is not currently available. This study was undertaken to assess whether the continuous monitoring of oxygenator exhaust carbon dioxide tension (PexCO2) can be used to reflect P(a)CO2 during CPB. A total of 33 patients undergoing CPB for cardiac surgery were included in the study. During normothermia (37 degrees C) and stable hypothermia (31 degrees C), the values of PexCO2 from the oxygenator exhaust outlet were monitored and compared simultaneously with the P(a)CO2 values. Regression and agreement analysis were performed between PexCO2 and temperature corrected-P(a)CO2 and temperature uncorrected-P(a)CO2. At normothermia, a significant correlation was obtained between PexCO2 and P(a)CO2 (r = 0.79; p < 0.05); there was also a strong agreement between PexCO2 and P(a)CO2 with a gradient of 3.4 +/- 1.9 mmHg. During stable hypothermia, a significant correlation was obtained between PexCO2 and the temperature corrected-P(a)CO2 (r = 0.78; p < 0.05); also, there was a strong agreement between PexCO2 and temperature corrected-P(a)CO2 with a gradient of 2.8 +/- 2.0 mmHg. During stable hypothermia, a significant correlation was obtained between PexCO2 and the temperature uncorrected-P(a)CO2 (r = 0.61; p < 0.05); however, there was a poor agreement between PexCO2 and the temperature uncorrected-P(a)CO2 with a gradient of 13.2 +/- 3.8 mmHg. Oxygenator exhaust capnography could be used as a mean for continuously monitoring P(a)CO2 during normothermic phase of cardiopulmonary bypass as well as the temperature-corrected P(a)CO2 during the stable hypothermic phase of CPB.     

Inflammatory and hemostatic response to cardiopulmonary bypass in pediatric population: feasibility of seriological testing of multiple biomarkers

Perioperative myocardial and cerebral damages are the major determinants of postoperative morbidity and mortality in pediatric cardiac surgery. Cardiopulmonary bypass (CPB) causes alterations in the levels of biomarkers related to inflammation, tissue damage, and other tissue pathologies. Early and accurate evaluation of inflammation and tissue damage would therefore be clinically useful. Our objective is to assess the suitability of using Multi-Analyte Profiling (MAP) (Rules Based Medicine, Austin, TX, USA) in pediatric cardiac surgery as a potential surrogate marker of clinical outcome. MAP technology platform allowed us to analyze 90 different biomarkers using only 100μL of plasma to detect any changes in the levels of 90 biomarkers. Plasma samples (100μL) were collected at five different time points: 1. before midline incision; 2. on CPB for 3-5min; 3. at the end of CPB; 4. 1h after CPB; and 5. 24h after CPB. After removing the outliers, the average and standard deviation of the values obtained from the 10 patients were calculated for each time point. The average values of each biomarker at each time point were then compared to each other and to the baseline. The pilot protocol included 10 patients (ages from 3 months to 4 years old) with similar Jenkins risks stratifications who underwent nonpulsatile CPB. We detected changes in the levels of 90 biomarkers. Biomarkers were assessed in groups. Myeloperoxidase (MPO) and pregnancy-associated plasma protein A (PAPP-A) were the earliest markers to rise with 49- and 18-fold increases 3-5min after the onset of CPB, respectively. The most striking increase was noted in the heart-type fatty acid-binding protein (FABP) levels. FABP increased 25, 193, 151, and 4-fold at time points 2, 3, 4, and 5, respectively. Surges in the novel markers of injury were followed by the markers of inflammation (i.e., C-reactive protein, interleukins) peaking at 24h after CPB. This pilot study shows that it is possible to measure 90 different biomarkers using only a very small sample of plasma to evaluate the effects of CPB. Novel markers of tissue injury (FABP, PAPP-A, or MPO) are the earliest markers to rise. Serial monitoring of multiple biomarkers may help to predict and improve outcomes after pediatric cardiac surgery.     

Cisatracurium pharmacokinetics and pharmacodynamics during hypothermic cardiopulmonary bypass in infants and children

Background: Hypothermia potentiates neuromuscular blockade in adults during cardiopulmonary bypass (CPB) but the pediatric literature is sparse. Temperature‐dependent Hoffman degradation of cisatracurium may allow reduction in infusion rate (IR) during hypothermia. The effect of hypothermic CPB on the pharmacokinetics (PK) and pharmacodynamics (PD) of cisatracurium has not been described in children. Methods and materials: Using neuromuscular monitoring with a Datex Relaxograph, cisatracurium IR was adjusted to obtain a pseudo‐steady state during each phase of surgery (pre‐CPB, CPB, post‐CPB). Paired samples were taken at each phase. Cisatracurium plasma concentrations (Cpss) were determined by HPLC. Core and skin temperatures were recorded. Results: Data from ten infants were analyzed: Group 1: mean 33.6°C; Group 2: mean 21.9°C. To maintain T1% between 5% and 10% in Group 2, the IR was decreased by a mean of 89% (P < 0.001). IR was not significantly different in Group 1. Post‐CPB IR approximated pre‐CPB rates in both groups. During CPB, Cpss fell by 27% in Group 1 and by 50% in Group 2 (P = 0.039). Post‐CPB Cpss was not significantly different to pre‐CPB in either group. Clearance did not change significantly in Group 1 but fell significantly in Group 2 during CPB (P = 0.002). Clearance post‐CPB was unchanged from pre‐CPB. Conclusions: Cisatracurium IR may be decreased by around 60% during CPB with moderate hypothermia but can be maintained at baseline during mild hypothermia.     

中低温减少体外循环下瓣膜置换术中丙泊酚剂量研究

目的以脑电频谱指数(BIS)为参考,探讨不同温度体外循环(CPB)下行瓣膜置换术患者丙泊酚的合适剂量。方法选择60例ASAⅡ-Ⅲ级择期行瓣膜置换术患者,根据术中最低鼻咽温分为2组:浅低温组(32℃,n=30)和中低温组(28℃,n=30)。术中调整丙泊酚剂量,保持BIS值处于40～60。分别于转机前(T1)、阻断升主动脉前(T2)、阻断升主动脉(T3)、开放升主动脉(T4)和停机后(T5)5个时间点,记录患者BIS值和丙泊酚剂量。结果患者均存活出院。组N患者转机前、停机后丙泊酚剂量分别为(4.6±1.3)mg/kg.hr和(4.3±1.6)mg/kg.hr,组H分别为(4.3±1.3)mg/kg.hr和(4.0±1.5)mg/kg.hr,差异均无统计学意义(P>0.05)。CPB转机开始后2组丙泊酚用量均较转机前明显减少,差异具有统计学意义(组N为2.4±1.2 mg/kg.hr,组H为1.2±0.5mg/kg.hr,P<0.01)。T3时间点中低温组较浅低温组下降明显,差异具有统计学意义(P<0.01)。无1例发生术中知晓现象。结论中低温CPB下行瓣膜置换术时,转机开始后应适量减少丙泊酚剂量。     

肺动脉灌注低温保护液减轻体外循环肺内炎性反应

目的　研究肺动脉灌注低温保护液减轻体外循环肺内炎性反应的作用。方法　 4 0例行法洛四联症 (TOF)根治术的病儿随机分为肺保护组 2 0例 ,对照组 2 0例。肺保护组体外循环期间肺动脉灌注低温肺保护液 ,对照组行常规TOF根治术。围手术期监测血浆肿瘤坏死因子 (TNF α)水平。收集术后6h气管吸出物 ,检测其中炎性介质白细胞介素 (IL) 6、IL 8水平。征得病儿家属同意 ,术后取右下肺组织活检 ,观察组织内炎性反应情况。同时监测围手术期肺功能及临床指标。结果　肺保护组血浆中TNF α水平低于对照组 ,以回ICU 0h、2 4h差异显著 (P <0 0 1、P <0 0 5 ) ;术后 6h内气管吸出物中IL 6和IL 8水平肺保护组低于对照组 (P <0 0 1) ;肺组织活检对照组可见中性粒细胞浸润 ,肺保护组无明显病理改变。肺保护组术后肺泡 -动脉氧分压差 (A aO2 )较对照组低 ,以回ICU 0h、12h和 2 4h差异显著(P <0 0 5、P <0 0 1和P <0 0 5 ) ;肺保护组呼吸机辅助通气时间短于对照组 (P <0 0 1)。结论　肺动脉灌注低温保护液可明显减轻体外循环中肺内的炎性反应和改善肺功能。     

Whole body oxygen consumption after hypothermic cardiopulmonary bypass

Whole body oxygen consumption and the substrate for energy production during the post-bypass period have not been clarified. We hypothesized that the substrate composition for energy production during post-bypass period might be different from that during pre-bypass period because of surgical diabetic state induced by hypothermic cardiopulmonary bypass (CPB). We measured whole body oxygen consumption, carbon dioxide production and respiratory quotient by the gas exchange method using the Datex Deltatrac before and after hypothermic cardiopulmonary bypass. We also measured oxygen consumption by Ficks principle. Whole body oxygen consumption (P 0.001) and carbon dioxide production (P 0.05) increased significantly above pre-CPB values after the termination of CPB. Respiratory quotient (P 0.01) decreased significantly below pre-CPB values after the termination of CPB. We conclude that oxygen consumption increased significantly above pre-bypass values after the termination of hypothermic cardiopulmonary bypass at least under the fentanyl, diazepam, chlorpromazine anesthesia with continuous infusion of nitroglycerin and nicardipine. The changes in respiratory quotient suggest a relatively higher ratio of lipid metabolism for energy production during post-bypass period.(Maruyama K, Hashimoto H, Nakamura K, et al.: Whole body oxygen consumption after hypothermic cardiopulmonary bypass. J Anesth 7: 1–7, 1993)