Fluid extravasation during cardiopulmonary bypass in piglets--effects of hypothermia and different cooling protocols

BACKGROUND: Hypothermic cardiopulmonary bypass (CPB) is associated with capillary fluid leak and edema generation which may be secondary to hemodilution, inflammation and hypothermia. We evaluated how hypothermia and different cooling strategies influenced the fluid extravasation rate during CPB. METHODS: Fourteen piglets were given 60 min normothermic CPB, followed by randomization to two groups: 1: rapid cooling (RC-group) ( approximately 15 min to 28 degrees C); 2: slow cooling (SC-group) ( approximately 60 min to 28 degrees C). Ringer's solution was used as CPB prime and for fluid supplementation. Fluid input/losses, plasma volume, colloid osmotic pressures (plasma, interstitial fluid), hematocrit, serum-proteins and total tissue water (TTW) were measured and fluid extravasation rates calculated. RESULTS: Start of normothermic CPB resulted in a 25% hemodilution. During the first 5-10 min the fluid level of the reservoir fell markedly due to an intravascular volume loss necessitating fluid supplementation. Thereafter a steady state was reached with a constant fluid need of 0.14 +/- 0.04 ml kg-1 min-1. After start of cooling the fluid needs increased in the following 30 min to 0.91 +/- 0.11 ml kg-1 min-1 in the RC group (P < 0.001) and 0.63 +/- 0.10 ml kg-1 min-1 in the SC-group (P < 0.001) with no statistical between-group differences. Fluid extravasation rates after start of hypothermic CPB increased from 0.20 +/- 0.08 ml kg-1 min-1 to 0.71 +/- 0.13 (P < 0.01) and 0.62 +/- 0.13 ml kg-1 min-1 (P < 0.05) in the RC- and SC-groups, respectively, without any changes in degree of hemodilution. TTW increased in most tissues, whereas the intravascular albumin and protein masses remained constant with no between group differences. CONCLUSION: Hypothermia increased fluid extravasation during CPB independent of cooling strategy. Intravascular albumin and protein masses remained constant. Since inflammatory fluid leakage usually results in protein rich exudates, our data with no net protein leakage may indicate that mechanisms other than inflammation could contribute to fluid extravasation during hypothermic CPB.     

Low arterial pressure during cardiopulmonary bypass in piglets does not decrease fluid leakage

BACKGROUND: Cardiopulmonary bypass (CPB) is associated with increased fluid filtration occasionally leading to post-operative organ dysfunction. One of the factors determining fluid filtration is the capillary hydrostatic pressure which depends on arterial pressure, venous pressure and pre- to post-capillary resistance ratio. The purpose of this study was to assess whether lowering of the mean arterial pressure and/or the central venous pressure could reduce fluid extravasation during normothermic and hypothermic CPB. METHODS: Seven piglets were given nitroprusside to a mean arterial pressure of 35-40 mmHg during 60 min of normothermic and 90 min of hypothermic CPB (LP group). They were compared with a control group (C group, n = 7) without blood pressure interventions. Blood chemistry, net fluid balance, plasma volume, colloid osmotic pressure in plasma and interstitial fluid, intravascular protein masses, fluid extravasation rate and total tissue water content were measured or calculated. RESULTS: Mean arterial pressure was significantly lower in the LP group than in the C group during CPB. Plasma volume tended to increase in the LP group (P > 0.05), but remained essentially unchanged in the C group. Net fluid balance in the LP group was more positive than in the C group 30 min after CPB start [1.02 (0.15) vs. 0.56 (0.13) ml/kg/min (Mean (SEM) P < 0.05)]. Fluid extravasation rate tended to be higher in the LP group and total tissue water content of the gastrointestinal tract, left myocardium and skin was significantly elevated compared with the C group. CONCLUSION: During CPB, lowering of the mean arterial pressure using nitroprusside did not reduce fluid extravasation. On the contrary, the data may implicate an increase in edema formation during low pressure CPB.     

Fluid shift is moderate and short-lived during acute crystalloid hemodilution and normothermic cardiopulmonary bypass in piglets

BACKGROUND: Crystalloids are commonly used as priming solutions during cardiopulmonary bypass (CPB). Consequently, hemodilution is a regular occurrence at the start of a CPB. This study describes the time-course variations of hemodynamic parameters, plasma volume (PV) and fluid exchange following crystalloid hemodilution at start of normothermic CPB. METHODS: Forty-five anesthetized piglets were given 60-min normothermic CPB. Ringer's solution was used as priming solution and maintenance fluid. Fluid input/losses, PV, colloid osmotic pressures (plasma/interstitium), hematocrit, and s-proteins were measured, and fluid extravasation rates (FER) and intravascular protein-masses calculated. RESULTS: Start of CPB resulted in a 25-30% hemodilution. To keep the fluid level of the CPB-reservoir constant after start of bypass, fluid addition [2.08 +/- 0.36 (mean +/- SEM) ml kg(-1) min(-1)] was necessary during the first 5 min. Thereafter the fluid needs to be leveled off [0.17 +/- 0.03 ml kg(-1) min(-1) (10-60 min), P < 0.001]. Fluid extravasation rate increased immediately following hemodilution from a baseline value of 0.08 +/- 0.01 to 1.75 +/- 0.34 ml kg(-1) min(-1) with a delayed decrease compared to fluid additions, to reach a 'steady-state' level of 0.22 +/- 0.03 ml kg(-1) min(-1) after 30 min (P < 0.001). Differences in time-course variations between fluid added and fluid extravasated were accompanied by changes in PV and mean arterial pressure. The colloid osmotic gradient decreased about 50% throughout the study and could partly explain the increased FER. CONCLUSION: Acute crystalloid hemodilution contributes to fluid overload during normothermic CPB. The resulting increase in fluid extravasation is, however, moderate, short-lived and levels off to baseline values within 30 min.     

Dynamic evaluation of fluid shifts during normothermic and hypothermic cardiopulmonary bypass in piglets

BACKGROUND: Edema, generalized overhydration and organ dysfunction commonly occur in patients undergoing open-heart surgery using cardiopulmonary bypass (CPB) and induced hypothermia. Activation of inflammatory reactions induced by contact between blood and foreign surfaces are commonly held responsible for the disturbances of fluid balance ("capillary leak syndrome"). We used an online technique to determine fluid shifts between the intravascular and the interstitial space during normothermic and hypothermic CPB. METHODS: Piglets were placed on CPB (fixed pump flow) via thoracotomy in general anesthesia. In the normothermic group (n=7), the core temperature was kept at 38 degrees C prior to and during 2 h on CPB, whereas in the hypothermic group (n=7) temperature was lowered to 28 degrees C during bypass. The CPB circuit was primed with acetated Ringer's solution. The blood level in the CPB circuit reservoir was held constant during bypass. Ringer's solution was added when fluid substitution was needed (falling blood level in the reservoir). In addition to invasive hemodynamic monitoring, fluid input and losses were accurately recorded. Inflammatory mediators or markers were not measured in this study. RESULTS: Cardiac output, s-electrolytes and arterial blood gases were similar in the two groups in the pre-bypass period. At start of CPB the blood level in the machine reservoir fell markedly in both groups, necessitating fluid supplementation and leading to a markedly reduced hematocrit. This extra fluid need was transient in the normothermic group, but persisted in the hypothermic animals. After 2 h of CPB the hypothermic animals had received 7 times more fluid as compared to the normothermic pigs. CONCLUSION: We found strong indications for a greater fluid extravasation during hypothermic CPB compared with normothermic CPB. The experimental model using the CPB-circuit reservoir as a fluid gauge gives us the opportunity to study further fluid volume shifts, its causes and potential ways to optimize fluid therapy protocols.     

Postpneumonectomy Empyema in Pulmonary Carcinoma Patients

The postpneumonectomy empyema of 12 pulmonary carcinoma patients was treated with open window thoracostomy and, whenever possible, with later closure of the thoracostomy. Six of the patients had no bronchial fistula and the pleural cavity of four of them remained healed after the closure of the thoracostomy. Six patients had bronchopleural fistulae. The pleural cavity of one of them remained healed after the closure of the thoracostomy following spontaneous healing of a small bronchial fistula. The cases, in which closure of thoracostomy was not undertaken on account of open bronchial fistula and those in which recurrence of empyema necessitated reopening of the thoracostomy, were managed satisfactorily with permanent open window thoracostomy.     

The correlation of fluid balance changes during cardiopulmonary bypass to mortality in pediatric and congenital heart surgery patients

Edema acquired during the perioperative period has long been associated with increased mortality. Edema acquired during cardiopulmonary bypass (CPB) may contribute to this mortality. The intent of this retrospective study was to test the premise that edema in the form of a positive fluid balance change (FBC) acquired during CPB correlated to mortality. If so, FBC from the beginning of CPB (baseline; FBC = 0) to the end of CPB may need to be monitored, measured, and controlled on CPB with the same ardor as blood pressure and pH. This retrospective analysis reviewed the FBC of 1540 pediatric and congenital heart surgery patients at the end of CPB. Additions and subtractions of fluid to the combined patient/CPB circuit were routinely quantified during CPB procedures and during periods of modified ultrafiltration (MUF). The primary outcome assessed was mortality during hospitalization. The overall mortality of the 1540 patients was 5.65% from all causes. Eighty percent (n = 1226, mortality = 4.65%) of the patients had a zero or negative FBC immediately after CPB/MUF. Twenty percent (n = 314, mortality = 9.55%) had a positive FBC. Positive FBC patients tended to be in higher risk categories, weighed more, and had longer pump times (p < .05) with an adjusted odds ratio for mortality of 1.73 (1.01-2.96, 95% confidence interval). There is a correlation between edema acquired during CPB and increased mortality in pediatric and congenital heart surgery patients. The potential exists for the perfusionist to optimize the fluid balance changes while on CPB to reduce mortality rates.     

Reduced fluid gain during cardiopulmonary bypass in piglets using a continuous infusion of a hyperosmolar/hyperoncotic solution

BACKGROUND: The aim of this study was to evaluate how a continuous infusion of a hyperosmolar/hyperoncotic solution influences fluid shifts and intracranial pressure during cardiopulmonary bypass in piglets. METHODS: Fourteen animals, randomized to the control (CT) group or the hypertonic saline/hydroxyethyl starch (HyperHaes) (HSH) group, received acetated Ringer's solution as prime and supplemental fluid. The HSH group received, in addition, HyperHaes 1 ml/kg/h. After 1 h of normothermic cardiopulmonary bypass, hypothermic cardiopulmonary bypass (28 degrees C) was initiated and continued for 90 min. Fluid balance, plasma volume, tissue water content, acid-base parameters and intracranial pressure were recorded, and protein masses and fluid extravasation rates were calculated. RESULTS: At the start of normothermic cardiopulmonary bypass, the fluid extravasation rates (ml/kg/min) increased from 0.19 (0.06) to 1.57 (0.71) and 0.19 (0.09) to 0.82 (0.14) in the CT and HSH groups, respectively, with no between-group differences (P = 0.081) During hypothermic cardiopulmonary bypass, the fluid extravasation rates (ml/kg/min) increased from 0.19 (0.14) to 0.51 (0.10) (P < 0.01) and 0.15 (0.08) to 0.33 (0.08) (P < 0.05), respectively, with significantly lower extravasation rates in the HSH group (P < 0.01). In the HSH group, the total fluid gain during cardiopulmonary bypass decreased by about 50% (P < 0.05) and the tissue water content was significantly lower in the left and right heart as well as in the lungs. The intracranial pressure remained stable in the HSH group, but increased in the CT group. CONCLUSIONS: A continuous infusion of HSH (HyperHaes) during cardiopulmonary bypass reduced the fluid extravasation rate and the total fluid gain during bypass. No electrolyte or acid-base disturbances were present. The intracranial pressure remained stable in the HSH group.     

Influence of intraoperative fluid volume on cardiopulmonary bypass hematocrit and blood transfusions in coronary artery bypass surgery

A hematocrit (Hct) of less than 25% during cardiopulmonary bypass (CPB) and transfusion of homologous packed red blood cells (PRBC) are each associated with an increased probability of adverse events in cardiac surgery. Although the CPB circuit is a major contributor to hemodilution intravenous (IV) fluid volume may also significantly influence the level of hemodilution. The objective of this study was to explore the influence of asanguinous IV fluid volume on CPB Hct and intraoperative PRBC transfusion. After Institutional Review Board approval, a retrospective chart review of 90 adult patients that had undergone an elective, isolated CABG with CPB was conducted. Regression analysis was used to determine if pre-CPB fluid volume was associated with the lowest CPB Hct and the incidence of an intraoperative PRBC transfusion. In separate multivariate analyses, higher pre-CPB fluid volume was associated with lower minimum CPB Hct (p < .0001), and higher minimum CPB Hct was associated with a decreased probability of PRBC transfusion (p < .0001). Compared to patients that received <1600 mL (n = 55) of pre-CPB fluid, those that received >1600 mL (n = 35) had a decreased mean low CPB Hct (22.4% vs 25.6%, p < .0001), an increased incidence of a CPB Hct <25% (74% vs. 38%, p = .0008) and PRBC transfusion (60% vs. 16%, p < .0001), and increased median PRBC units transfused (2.0 vs 1.0, p = .1446) despite no significant difference in gender, age, patient size, baseline Hct, or CPB prime volume. Patients that received a PRBC transfusion (n = 30) received a significantly higher volume of pre-CPB fluid than nontransfused patients (1800 vs. 1350 mL, p = .0039). These findings suggest that pre-CPB fluid volume can significantly contribute to hemodilutional anemia in cardiac surgery. Optimizing pre-CPB volume may preserve baseline Hct and help limit intraoperative hemodilution.     

Interstitial fluid volume during cardiac surgery measured by means of a non-invasive conductivity technique

Fluid accumulation in the interstitium is frequently found after cardiac surgery. In extreme this can lead to pulmonary and myocardial oedema. The origin of this accumulation is not exactly known and may be twofold. It is probably a combination of the noninfectious whole body inflammatory response and a change in Starling forces due to a decrease in colloid osmotic pressure (COP) which is caused by the primed extracorporeal circuit. To study the changes in interstitial fluid volume (ISFV) a non-invasive conductivity technique was used. The relationship between temperature and conductivity was first investigated in vitro . A linear relationship was found between conductivity and different saline solutions and temperature. From the in vitro experiments it can be concluded that temperature corrected conductivity does not depend on haematocrit. After the in vitro experiments eleven patients undergoing cardiac surgery were studied. During the first minutes of cardiopulmonary bypass (CPB) a steep significant decrease in COP to 61.4±6.9% (from 19.6±1.1 to 12.0±1.2 mmHg), and a rise in ISFV to 105.5±2.8% (from 12.3±1.4 mS to 14.0±1.3 mS) was noticed. After this decrease COP increased significantly, till the end of the operation, but did not reach the pre-operative level. An increase in ISFV was noticed till the rewarming point. After this point no significant change in ISFV was noticed. Furthermore, a significant correlation was found between the fluid balance and the ISFV increase at the start, at the end of CPB, and at the end of the operation. From the in vivo experiments it can be concluded that the non-invasive conductivity technique in a valuable acquisition for the investigation of ISFV changes during cardiac surgery. It shows that the changes in ISFV are mainly disturbed during the first part of CPB probably due to a marked decrease in COP.     

Effects of cardiopulmonary bypass and hypothermia on electroencephalographic variables

We studied the effects of hypothermia and cardiopulmonary bypass (CPB) on four depth of anaesthesia monitors; spectral edge frequency (SEF), median frequency (MF), bispectral index (BIS) and auditory evoked potential index (AEPIndex) in 12 patients during uneventful cardiac anaesthesia. Each variable was recorded simultaneously at 10 periods during anaesthesia. All four variables were not affected by the transition to CPB. During hypothermia, values of AEPIndex, MF and SEF were tightly distributed but values of BIS were very variable and overlapped with those before induction of anaesthesia. The variability decreased during rewarming. The values of AEPIndex throughout the anaesthesia never overlapped with those before induction of anaesthesia. The AEPIndex was the most stable and reliable as a depth of anaesthesia monitor among the four variables in cardiac bypass surgery.     

6%羟乙基淀粉130/0.4体外循环预充对心脏手术患儿血浆胶体渗透压及乳酸水平的影响

Objective To investigate the effects of hydroxyethyl starch 130/0.4 (HES) used as priming fluid for cardiopulmonary bypass (CPB) on the plasma colloid osmotic pressure (COP) and lactic acid (LAC) concentration in infants undergoing cardiac surgery.Methods Forty infants of either sex with age ≤6 yr undergoing cardiac surgery with CPB were randomly divided into 2 groups (n =20 each): HES group and control group. The left radial artery and the right internal jugular vein were cannulated for blood pressure (BP) and the central venous pressure (CVP) monitoring. Arterial blood gases, blood LAC concentration, hemoglobin (Hb), hematocrit (Hct), mean arterial pressure (MAP) and nasopharyngeal temperature were measured and recorded immediately before and 5 min after aortic cross-clamping, at the end of CPB and operation. Plasma COP was measured before induction of anesthesia (T1), at 5 and 30 min of CPB (T2 and T3, respectively), before routine ultra-filtration (T4), at the end of CPB (T5) and2 h in ICU (T6).Results The plasma LAC concentration was significantly lower and the COP significantly higher in HES group than in control group (P＜0.05 or 0.01).The plasma LAC concentration increased after aortic cross-clamping, reached the peak at the end of CPB and then declined at the end of operation, but was still higher than that before aortic cross-clamping in both groups. Plasma COP was significantly decreased during CPB as compared with the baseline at T1, but increased at T6 in both groups.Conclusion Using HES 130/0.4 as pdming fluid for CPB can effectively improve plasma COP and reduce blood LAC level in infants undergoing cardiac surgery with CPB.     

Fluid overload during cardiopulmonary bypass is effectively reduced by a continuous infusion of hypertonic saline/dextran (HSD)

Objective. Cardiopulmonary bypass (CPB) is associated with fluid overload. We examined how a continuous infusion of hypertonic saline/dextran (HSD) influenced fluid shifts during CPB. Materials and methods. Fourteen animals were randomized to a control-group (CT-group) or a hypertonic saline/dextran-group (HSD-group). Ringer's solution was used as CPB-prime and as maintenance fluid at a rate of 5 ml/kg/h. In the HSD group, 1 ml/kg/h of the maintenance fluid was substituted with HSD. After 60 min of normothermic CPB, hypothermic CPB was initiated and continued for 90 min. Fluid was added to the CPB-circuit as needed to maintain a constant level in the venous reservoir. Fluid balance, plasma volume, total tissue water (TTW), intracranial pressure (ICP) and fluid extravasation rates (FER) were measured/calculated. Results. In the HSD-group the fluid need was reduced with 60% during CPB compared with the CT-group. FER was 0.38(0.06) ml/kg/min in the HSD-group and 0.74 (0.16) ml/kg/min in the CT-group. TTW was significantly lower in the heart and some of the visceral organs in the HSD-group. In this group ICP remained stable during CPB, whereas an increase was observed in the CT-group (p <0.01). Conclusions. A continuous infusion of HSD reduced the fluid extravasation rate and total fluid gain during CPB. TTW was reduced in the heart and some visceral organs. During CPB ICP remained normal in the HSD-group, whereas an increase was present in the CT-group. No adverse effects were observed.     

Fluid balance and pulmonary functions during and after coronary artery bypass surgery: Ringer's acetate compared with dextran, polygeline, or albumin

The effects on fluid balance, pulmonary tunctions and economics were evaluated in a randomized comparison of one colloid free and three colloid containing fluid regimens, for 48 hours during and after coronary artery-bypass (CAB) surgery. A standard regimen for anaesthesia, extracorporeal circulation and monitoring was used. Only Ringer's acetate (RAc) was used as priming solution for extracorporeal circulation. Forty patients were randomized to receive either RAc, polygeline 35 mg-ml^-1 (Haemaccel®), dextran 70 (Macrodex®) 60 mg ml^-14, or albumin 40 mg-ml^-1 in saline whenever fluid volume was needed to stabilize haemodynamics. At the end of the operation, fluid retention was significantly lower in patients receiving polygeline and dextran 70, compared with patients receiving RAc. At 48 hours, however, there were no differences in cumulative fluid balance. Patients in the colloid groups postoperatively had a higher serum colloid osmotic pressure (s-COP), bui a higher net lung capillary filtration pressure (AP) only on the second postoperative day than the RAc group. However, this did not adversely atfect intrapulmonary venous admixture, arterial oxygen tension, or time on respirator in the RAc group compared with the colloid groups. The most expensive colloid fluid regimen (albumin) cost about 230 USS more per patient than the RAc fluid regimen. We conclude that Ringer's acetate for volume replacement to stabilize haemodynamics during and after CAB surgery is associated with increased fluid retention only during the intraoperative period, compared with dextran 70 or polygeline, and with a lower serum colloid osmotic pressure and net lung capillary filtration pressure postoperatively, compared with all three colloid groups. This does not affect pulmonary functions adversely. Thus, the RAc regimen is clinically fully acceptable and economically more favourable than the polygeline, dextran 70, and albumin-containing fluid regimens.     

深低温低流量灌注与降温期血气管理对乳猪脑保护的对照研究

目的：在深低渐体外循环中比较降温期pH稳态血气管理和深低温阶段低流量灌注对脑保护的作用能力。方法：24头乳猪根据不同的体外循环脑保护处理方法分成4组，A组：深低温停循环、降温期alpha稳态血气管理；B组：深低温停循环、降温期pH稳态血气管理；C组：深低温低流量、降温期alpha稳态血气管理；D组：深低温低流量、降温期pH稳态血气管理。比较不同脑保护方法和体外循环阶段对脑血流（CBF）、脑氧代谢率（CMRO2）、脑乳酸含量、脑水含量和脑电图（EEG）的影响。结果：B组、D组降温末CBF均高于A组、C组；而CMRO2则低于A组、C组；B组、D组降温期EEC平坦波出现早。C组、D组复温期CBF、CMRO2和EEG恢复好于A组、B组。复温末A组、B组颈内静脉乳酸含量显著高于C组、D组，脑水含量组间差异无显著性。结论：深低温体外循环流量灌注对脑保护的作用能力强于降温期pH稳态血气管理，两种方法配合应用具有脑保护的协同作用。     

兔体外循环中聚乙二醇牛血红蛋白偶联物对平均动脉压、胶体渗透压及p50的影响

目的探讨在体外循环(CPB)预充液中加入聚乙二醇牛血红蛋白偶联物(PEG-bHb)对兔平均动脉压(MAP)、胶体渗透压(COP)及p50的影响。方法24只成年健康大耳白兔(2．59±0．19)kg,通过股动脉、颈静脉插管建立体外循环通路,转流1h。随机分成3组,对照组(n =8),以晶／胶体液作为体外循环预充液；实验组1(n=8),在预充液中加入PEG-bHb,PEG-bHb占总容量(兔循环血量+预充量)的5％；实验组2(n=8),预充液中加入PEG-bHb,占总容量(兔循环血量+预充量)的15％,体外循环开始后放出自体血(放血量占兔循环血量的20％),CPB结束后将自体血回输。每组监测CPB前和CPB中平均动脉压；在CPB前、CPB中15、50 min、CPB后1 h测胶体渗透压及动脉血p50值。结果实验组1和实验组2在CPB中的MAP均高于对照组,但只有实验组2在转中10 min时与对照组相比差异有统计学意义(P＜0．05)；实验组2在CPB中COP值均较高；实验组1动脉血p50值较对照组高。结论PEG-bHb占实验兔循环血量+预充量的5％对CPB中和CPB后MAP和COP无明显影响,并且由p50提示向组织释放O_2量增多,此量可安全用于CPB预充；另外,在CPB前放出部分自体血将对CPB中血液保护发挥一定作用。     

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.     

浅低温体外循环对心脏手术婴幼儿患者罗库溴铵药效学的影响

目的 探讨浅低温体外循环(CPB)对心脏手术婴幼儿患者罗库溴铵药效学的影响.方法 择期行房间隔缺损修补术或室间隔缺损修补术的患儿50例,年龄6月～3岁,体重6～15 kg,NY-HA心功能分级和ASA分级均为Ⅰ或Ⅱ级.采用随机数字表法,将患儿随机分为2组(n=25):深低温组和浅低温组.深低温组CPB过程中将目标温度设定为28～30℃,浅低温组CBP过程中将目标温度设定为32～34℃.静脉注射咪达唑仑0.1 mgkg、异丙酚2mg/kg和芬太尼6～8μg/kg麻醉诱导,启动肌松监测,定标稳定后静脉注射罗库溴铵600μg/kg,当T1达最大抑制时行气管插管,机械通气,维持PET CO2 30～40mm Hg.间断静脉注射芬太尼和咪达唑仑维持麻醉.术中当T1恢复至基础值的75％时,静脉注射罗库溴铵200 μg/kg.分别于CPB前、CPB期间和CPB结束后,记录罗库溴铵起效时间、无反应期、临床作用时间和恢复指数.结果 与深低温组比较,浅低温组CPB期间起效时间、无反应期和临床作用时间缩短(P＜0.05).结论 与深低温CPB相比,浅低温CPB可缩短心脏手术婴幼儿患者罗库溴铵的起效时间和作用时间.