Hyperosmolar volume replacement in heart surgery]

The ideal solution for use in volume therapy is still a matter of debate. Hypertonic sodium (HS) solutions have been advocated for resuscitation from hemorrhagic shock (small volume resuscitation). As hypertonic fluids may also be of interest in cardiac surgery, the effects of a new HS solution were studied. METHODS. In 90 patients undergoing aorto-coronary bypass grafting studies were performed at three different periods: I (n = 30) after induction of anesthesia (before onset of the operation); II (n = 30) during cardiopulmonary bypass (CPB); III (n = 30) after termination of bypass. During these periods the patients were randomly allocated to one of three groups with 10 patients in each group: group 1 received a new hypertonic solution prepared in hydroxyethyl starch (HES) solution (72 g/l NaCl, 60 g/l HES, 2400 mosmol/l; HS-HES patients), group 2 received a 6% HES solution (200/0.5; HES patients), and group 3 received no volume infusion and served as controls. RESULTS. After the induction of anesthesia, significantly less HS-HES solution (4.5 +/- 0.5 ml/kg) than 6% HES solution (10.1 +/- 1.4 ml/kg) was necessary to double the baseline PCWP. The fluid balance during CPB was negative in the patients who had received HS-HES preoperatively (-0.03 +/- 0.01 ml/kg.min CPB), whereas 6% HES (+0.06 +/- 0.02 ml/kg.min CPB) and control patients (+0.13 +/- 0.03 ml/kg.min CPB) had a positive fluid balance. Both after the induction of anesthesia and after termination of bypass, CI increased more in the HS-HES group than in the HES patients, and it even decreased in the control group. SVR decreased in the HS-HES patients, whereas it increased in the control group. Rapid infusion of HS-HES during CPB was followed by a significant, but short-lasting decrease in MAP (-40 mmHg) and an increase in the oxygenator volume. Pulmonary gas exchange (= paO2) was least compromised in the HS-HES patients; the sodium concentration increased only in the HS-HES patients, but never exceeded 150 mmol/l. DISCUSSION. Cardiac surgery procedures offer a special situation for volume therapy as there is a possibility of deterioration in the macro- and microcirculation before, after, and during the period of CPB. Hemodynamic effects of the new HS-HES solution included an increase in CI and a decrease in SVR, which were not merely transient as has been reported which hypertonic saline solution used alone. It was also observed that HS-HES patients required significantly smaller volumes of fluids, both during CPB and during the early postoperative period. This effect seems to be due to a redistribution of interstitial fluid to the intravascular space, possibly decreasing tissue edema. CONCLUSION. The hypertonic saline HES solution adds a new dimension to volume therapy for cardiac surgery patients. The improvement in hemodynamics was effective and not only transient. Fluid requirements were significantly reduced during as well as after CPB, and pulmonary gas exchange was least compromised in these patients.     

Acute preoperative hemodilution in cardiac surgery: volume replacement with a hypertonic saline-hydroxyethyl starch solution.

Preoperative hemodilution (HD) is a recommended practice in cardiac surgery that conserves blood and reduces the complications of homologous blood transfusion. In 45 patients undergoing myocardial revascularization, HD was performed preoperatively. Withdrawn volume (10 mL/kg) was replaced either by a new hypertonic saline (HS) solution prepared in hydroxyethyl starch (HES) (2,400 mOsm/L, HS-HES group, n = 15) or by a standard low molecular weight hydroxyethyl starch solution (6% HES 200/0.5, HES group, n = 15) to maintain baseline PCWP (acute normovolemic hemodilution [ANH]). Fifteen comparable patients without HD served as controls. Significantly less HS-HES (210 +/- 20 mL) than HES 6% (890 +/- 90 mL) was necessary to sustain hemodynamics during HD. Stable cardiocirculatory conditions were obtained even after termination of bypass. Fluid balance during cardiopulmonary bypass as well as in the postoperative period was significantly lower in HS-HES-treated patients. With regard to hemodynamics, CI increased most in the HS-HES group (+36%), whereas systemic vascular resistance was lower in these patients. Right ventricular ejection fraction increased only in HS-HES patients (+15%). However, sodium concentration as well as osmolarity increased after volume replacement with HS-HES, without exceeding normal values. None of the patients suffered from organ failure. Pulmonary gas exchange (PaO2) was less compromised in the HS-HES patients. There were no renal function differences between the groups. In conclusion, HS solution prepared in HES is an attractive alternative for blood substitution in cardiac patients undergoing acute hemodilution for blood conservation.     

INFLUENCE OF HYPERTONIC VOLUME REPLACEMENT ON THE MICROCIRCULATION IN CARDIAC SURGERY

We have studied the effects of two types of volume replacementon the microcirculation in an open, controlled study in 45 patientsundergoing aorto-coronary bypass grafting whose pulmonary capillarywedge pressure (PCWP) was < 5 mm Hg. Hypertonic saline preparedin hydroxyethylstarch solution (HS-HES, n = 15) and6%HES200/0.5solution(6% HES; n = 15) were infused randomly before operation in orderto double the PCWP. Patients not given an infusion served ascontrols (n = 15). Skin micro-circulatory blood flow was investigatedby laser Doppler flow (LDF) measured simultaneously at the forearmand forehead before and after cardiopulmonary bypass (CPB).Less HS-HES (3.8 (SD 0.3) ml kg^–1) than 6% HES-solution(9.7 (1.5) ml kg^–1) was necessary to double baseline PCWP.There were no differences in heart rate and mean arterial pressure(MAP) between the groups. Cardiac index (Cl) increased significantlyin both volume groups (HS-HES max. +54%; 6% HES max. +30%).Systemic vascular resistance (SVR) decreased after infusionof HS-HES (30%) and after 6% HES(19%) and remained almost unchangedin the control group. Plasma viscosity decreased after infusionof HS-HES and increased slightly in control patients (+4%).In comparison with the 6% HES and particularly with the controlgroup, LDF was significantly greater after infusion of HS-HES(forearm +80%; forehead +28%). LDF during CPB and thereafterwas always greater than baseline values in the HS-HES group,whereas after bypass LDF was reduced in the 6% HES (5%) andparticularly in the control patients (30%). No differences intemperature (oesophageal, rectal, forearm, forehead) occurredbetween groups. Changes in MAP, Cl, SVR, haemoglobin and viscositydid not correlate with skin blood flow. It was concluded thatthe preoperative infusion of HS-HES resulted in a significantimprovement in microcirculation before, during and after CPB.     

Hydroxyethyl starch as a priming solution for cardiopulmonary bypass impairs hemostasis after cardiac surgery

We investigated the influence of hydroxyethyl starch (HES) as a priming solution for the cardiopulmonary bypass (CPB) circuit on postoperative hemostasis in 45 patients undergoing elective coronary artery bypass grafting. In a randomized sequence, 20 mL/kg of low-molecular-weight HES (HES 120; molecular weight 120,000 daltons), high-molecular-weight HES (HES 400; molecular weight 400,000 daltons), or 4% human albumin (ALB) was used as the main component of the CPB priming solution. The thromboelastographic values indicating the speed of solid clot formation (alpha-angle) and the strength of the fibrin clot (maximum amplitude and shear elastic modulus) were decreased up to 2 h after CPB in both HES groups. Four hours after the operation, blood loss through the chest tubes had increased in the HES groups: HES 120, mean 804 mL (range, 330-1390 mL); HES 400, mean 1008 mL (range, 505-1955 mL); and ALB, mean 681 mL (range, 295-1500 mL) (P < 0.05 between the HES 400 and ALB groups). We conclude that HES solutions, when given in doses of 20 mL/kg in connection with the CPB prime, compromise hemostasis after cardiac surgery. This effect appears related to formation of a less stable thrombus compared with that formed in the presence of ALB. IMPLICATIONS: The influence of hydroxyethyl starch (HES) on postoperative hemostasis was investigated in cardiac surgery. The thromboelastographic values indicated that HES solutions, when given in connection with the cardiopulmonary bypass prime, compromise hemostasis after cardiac surgery. This effect seems to occur through the formation of a less stable clot.     

小容量不同液体治疗对内毒素血症大鼠肾血流的影响

目的 评价小容量不同液体治疗对内毒素血症大鼠肾血流的影响.方法 清洁级雄性SD大鼠30只,体重180～250 g,随机分为5组(n=6):对照组(C组)、内毒素血症组(LPS组)、7.5%高渗氯化钠溶液组(HS组)、羟乙基淀粉130/0.4溶液组(HES组)和高渗氯化钠羟乙基淀粉40溶液组(HSH组).LPS组、HS组、HES组和HSH组经左侧颈总动脉导管注射LPS 1 mg/kg,C组注射等容量生理盐水.30 min后,C组和LPS组注射生理盐水4 ml/kg;HS组、HES组和HSH组分别注射7.5%高渗氯化钠溶液、羟乙基淀粉130/0.4溶液或高渗氯化钠羟乙基淀粉40溶液4 ml/kg.于给予LPS前、给予LPS后30 min、液体治疗后10、30、60 min时进行左肾脏超声多普勒检测,记录左肾动脉的收缩峰值血流速度(Vmax)、舒张末期血流速度(Vmax)和阻力指数(RI).取肾组织,观察病理学结果.结果 内毒素血症大鼠肾血流逐渐减弱,分布面积减小,肾皮质血流几乎消失,肾小管上皮细胞严重变性、崩解脱落、集合管内可见细胞碎片充塞,左肾段动脉Vmax和Vmin降低,RI升高(P＜0.01).与LPS组比较,HS组、HES组和HSH肾血流增强,Vmax和Vmin升高,RI降低,其中HSH组效果更佳(P＜0.01).结论 小容量羟乙基淀粉130/0.4溶液、高渗盐水和高渗氯化钠羟乙基淀粉40溶液治疗可增强内毒素血症大鼠肾血流,改善肾脏微循环;高渗氯化钠羟乙基淀粉40溶液效果更佳.     

Hypertonic saline solution-hetastarch for fluid resuscitation in experimental septic shock

Hypertonic colloid solutions have been found efficacious in the resuscitation from hemorrhagic/traumatic shock. The present study investigated the hemodynamic, gasometric, and metabolic effects of hypertonic colloids in endotoxic shock in the dog. Thirty minutes after administration of 3 mg/kg normal body weight of Escherichia coli endotoxin, dogs were randomly assigned to receive 10 mL/kg hydroxyethylstarch (HES) either in 0.9% NaCl (HES, 10 dogs) or in 7.5% NaCl (HT-HES, 10 dogs) in 30 min. Thereafter, 0.9% NaCl solution was administered in volumes adequate to maintain pulmonary artery balloon-occluded pressure at baseline levels. Total fluid administered averaged 64 +/- 30 mL/kg (mean +/- SD) in the HES group and 73 +/- 34 mL/kg in the HT-HES group. As these differences were not statistically significant, total sodium load was higher in the HT-HES group. The persistent volume effect was associated with persistently lower hematocrit and protein levels in the HT-HES group. Initial fluid resuscitation with HT-HES resulted in arterial pressure, cardiac filling pressures, cardiac output, stroke volume, and rates of oxygen delivery and oxygen consumption that were greater than those with HES. Vascular resistances were similar. Analysis of left ventricular function curves also indicated an improvement in cardiac performance. However, these effects almost completely vanished during the remainder of the study. In the HT-HES group, serum sodium and osmolality levels increased to 167 +/- 4 mEq/L and 344 +/- 4 mOsm/kg H2O, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cerebral ischemia caused by obstructed superior vena cava cannula is detected by near-infrared spectroscopy

OBJECTIVE: Bicaval venous cannulation is being used with increasing frequency in neonates and infants to avoid circulatory arrest. However, superior vena cava (SVC) cannula obstruction may result in cerebral ischemia with no change in blood pressure or mixed venous O2 saturation. The authors hypothesized that near-infrared spectroscopy (NIRS) would allow noninvasive detection of SVC cannula obstruction. METHODS: Fifteen Yorkshire piglets (9.07 +/- 0.20 kg) underwent total cardiopulmonary bypass (CPB) (100 mL/kg/min, pH-stat strategy, hematocrit of 20%) with ascending aortic and bicaval cannulations. Femoral arterial and SVC pressure were monitored as well as mixed venous O2 saturation. NIRS monitoring of tissue oxygenation index (TOI) as well as oxyhemoglobin and deoxyhemoglobin (HHb) was undertaken. Animals were cooled to an esophageal temperature of 25 degrees C over 20 minutes. CPB flow was reduced to 50 mL/kg/min for 20 minutes. Animals then underwent a 60-minute study period of continuous CPB at 50 mL/kg/min with manipulation of the SVC cannula: group 1, open; group 2, partial occlusion; and group 3, complete occlusion. Animals were rewarmed to 37 degrees C at full flow with the SVC cannula open. Cerebral blood flow was assessed at onset of CPB, at end of cooling, at end of low flow, at end of SVC manipulation period, and at end of rewarming using radioactive microspheres. RESULTS: CBF decreased to 27.9 +/- 1.5 mL/min/100 g with complete occlusion (p < 0.01 v group 1: 39.7 +/- 1.9, group 2, 38.3 +/- 2.0 mL/min/100 g) with no change in arterial pressure or mixed venous saturation. There were also significant differences in cerebral oxygen delivery between group 3 and other groups (p < 0.01). SVC pressure increased to 19.5 +/- 4.5 and 32.5 +/- 3.1mmHg with partial and complete occlusion. NIRS indicated significant cerebral ischemia with a decrease in TOI (p < 0.05; group 3 v group 1 and 2) and an increase in HHb (p < 0.05; group 3 v group 1). At the end of the study, significant acidosis was found in group 3 compared with group 1 (p < 0.05). CONCLUSION: SVC cannula obstruction causes cerebral ischemia with no change in blood pressure or venous oxygen saturation. In view of the difficulties and risks of CVP monitoring in babies, it is recommended to use other monitoring modalities such as NIRS to assess adequacy of cerebral perfusion if bicaval cannulation is used in neonates and infants.     

Effect of low-dose milrinone on gastric intramucosal pH and systemic inflammation after hypothermic cardiopulmonary bypass

OBJECTIVE: To investigate the usefulness of low-dose milrinone on gastric intramucosal pH (pHi) and systemic inflammation in patients undergoing hypothermic cardiopulmonary bypass (CPB). DESIGN: Prospective randomized study. SETTING: University hospital. PARTICIPANTS: Twenty patients scheduled for cardiac surgery. INTERVENTIONS: Ten patients were administered a low dose of milrinone, 0.25 microg/kg/min, from the initiation of CPB to 1 hour after admission to the intensive care unit. The other patients were administered saline. Supplemental inotropes and intravenous fluid were given to obtain adequate mean arterial blood pressure and pulmonary artery occlusion pressure. MEASUREMENTS AND RESULTS: Gastric pHi and carbon dioxide pressure (PCO2) were assessed by capnometric air tonometry. The difference between PCO2 and arterial carbon dioxide pressure (PaCO2), PCO2-gap, was also examined. Systemic inflammatory responses were evaluated by serum interleukin-6 and leukocyte counts. Hemodynamics, oxygen delivery index, and oxygen uptake index were monitored with catheters in the radial and pulmonary arteries (thermodilution). The hepatic venous blood flow and left ventricular flow were measured using transesophageal echocardiography. Milrinone prevented gastric intramucosal acidosis, detected as a decrease in pHi or an increase in PCO2-gap, without affecting hepatic venous blood flow. Increases in interleukin-6, leukocyte count, and oxygen uptake index, all of which developed after CPB, were significantly less in the milrinone group than in the control group. CONCLUSION: These results suggest that in patients undergoing hypothermic CPB, supplemental low-dose milrinone prevents gastric intramucosal acidosis and increases in some markers of systemic inflammation.     

Retrograde autologous priming: is it useful in elective on-pump coronary artery bypass surgery?

BACKGROUND: The effect of reduced cardiopulmonary bypass (CPB) prime volume by retrograde autologous priming (RAP) was studied. METHODS: Twenty patients undergoing elective coronary artery bypass grafting were randomized to either standard prime (SP) volume (1,602 +/- 202 mL crystalloid prime, n = 10) or RAP (395 +/- 150 mL). RAP was performed by draining crystalloid prime from the arterial and venous lines into a recirculation bag before CPB. Cardiac index, pulmonary vascular resistance index, systemic vascular resistance index, alveolar-arterial oxygen tension difference, pulmonary shunt fraction, extravascular lung water (EVLW), plasma colloid osmotic pressure (COP), crystalloid fluid balance, body weight, and clinical parameters were evaluated perioperatively. RESULTS: Demographic data and operative parameters were equal for patients in both groups. During CPB, COP was reduced by 55% in the SP group (9.8 +/- 2.0 vs 21.4 +/- 2.1 mm Hg) and by 41% in the RAP group (12.4 +/- 1.1 vs 20.9 +/- 1.8 mm Hg) (p = 0.008, SP vs RAP group). Compared with preoperatively, EVLW was unchanged in the RAP group 2 hours post-CPB, but it was elevated by 21% in the SP group (p = 0.002, SP vs RAP group). End-CPB crystalloid fluid balance was significantly reduced in the RAP group (1,857 +/- 521 vs 2,831 +/- 637 mL). Postoperative (day 2) weight gain in the SP group (1.5 +/- 1.2 kg, p = 0.021) was absent in the RAP group (0.1 +/- 0.9, NS). Postoperative time to full mobilization was shorter in the RAP group. Postpump cardio-respiratory function did not differ among groups. CONCLUSIONS: This small-scale pilot study indicates that by reducing crystalloid fluid administration and fall of COP during CPB, RAP reduces postpump EVLW accumulation and weight gain in uncomplicated coronary artery bypass graft patients with no associated effects on cardio-respiratory function.     

N-acetylcysteine reduces lung reperfusion injury after deep hypothermia and total circulatory arrest

OBJECTIVE: We hypothesized that the use of N-acetylcysteine would ameliorate the lung reperfusion injury observed after deep hypothermia and total circulatory arrest (DHTSA). METHODS: Experiments were carried out on 12 adult mongrel dogs of either sex weighing 25 to 30 kg. The animals were randomly divided into two groups of six animals each. All animals were cooled to an esophageal temperature of 15 degrees C during 30 minutes and underwent 60 minutes of DHTSA, followed by the reinstitution of cardiopulmonary bypass (CPB) and rewarming. Before rewarming, while 100 mL physiologic saline solution was added into the pump in group I, 50 mg/kg N-acetylcysteine(NAC) was given in group II. Heart rate, mean arterial pressure, pulmonary arterial pressure, left atrial pressure, central venous pressure, and cardiac output were recorded. To measure lung tissue malondialdehyde (MDA), water content and polymorphonuclear leukocytes (PMNs) count, lung tissue samples were taken before CPB and after weaning CPB. In addition, alveolar-arterial oxygen difference (AaDO(2))()for tissue oxygenation was calculated by obtaining arterial blood gas samples. Dynamic lung compliance (DLC) was measured before CPB and after CPB. RESULTS: MDA levels before CPB of 44.2 +/- 3.9 nmol/g tissue rose to 76.6 +/- 5.6 nmol/g tissue after weaning CPB in group I (p = 0.004). In group II also, the MDA levels increased from 43.5 +/- 4.2 to 57.4 +/- 5.6 nmol MDA/g tissue after weaning CPB (p = 0.006). The MDA increase in group II after CPB was found to be significantly lower than in group I (p = 0.006). The wet-to-dry lung weight ratio in the NAC group was 5.1 +/- 0.2, significantly less than in the control group (5.9 +/- 0.3), (p = 0.004). AaDO(2) significantly increased in the group I and II (p = 0.002 and p = 0.002, respectively); this elevation in group I was significant than in group II (p = 0.044). In histopathological examination, it was observed that neutrophil counts in the lung parenchyma rose significantly after CPB in both groups (p < 0.001). The increase in group I was significantly larger than group II (p < 0.001). CONCLUSIONS: Results represented in our study indicate that addition of NAC into the pump after DHTSA can reduce lung reperfusion injury.     

Effects of colloid or crystalloid administration on pulmonary extravascular water in the postoperative period after coronary artery bypass grafting

The effect of postoperative fluid management on pulmonary extravascular thermal volume (ETVL) as in index of pulmonary extravascular water after coronary artery bypass grafting was compared, using the thermal-dye technique, among five patients who received 5% albumin (group A), five patients who received 6% hydroxyethyl starch (group H), and five who received lactated Ringer's solution (group C). Intraoperatively, all patients received lactated Ringer's solution intravenously, and the cardiopulmonary bypass (CPB) circuit prime included 5% albumin. No statistically significant changes in ETVL occurred postoperatively in any group, nor did ETVL differ significantly between groups. After CPB, colloid osmotic pressure (COP) significantly decreased and pulmonary artery wedge pressure (WP) and the WP-COP gradient significantly increased in each group, implying an increase in transcapillary fluid flux. Cardiac index changed variably. Pulmonary shunt fraction (Qsp/Qt) did not change in groups A and C but decreased during CPB in group H (from 0.22 +/- 0.03 to 0.16 +/- 0.11). Postoperatively, patients in the three groups received similar volumes of fluids and had similar perioperative weight gains. By the next morning (AM1), COP increased in all groups, returning to levels noted before CPB in group C, and exceeding these levels in groups A and H. Wedge pressure was similar in all three groups on AM1. PaO2 decreased significantly, and alveolar-arterial oxygen partial pressure difference increased significantly in all groups on AM1. In Group H, Qsp/Qt returned to levels observed before CPB by AM1 (0.27 +/- 0.09). We conclude that in patients without postoperative increases in WP, ETVL changes minimally during CPB and is not influenced by the type of fluid administered as the primary volume replacement in the postoperative period.     

Perfusing and ventilating the patient's lungs during bypass ameliorates the increase in extravascular thermal volume after coronary bypass grafting

BACKGROUND: To test the hypothesis that bilateral extracorporeal circulation (ECC) (Drew technique) ameliorates the increase in extravascular thermal volume (ETV) observed after conventional cardiopulmonary bypass (CPB) in patients undergoing coronary artery bypass grafting. METHODS: Thirty-four consecutive patients underwent either bilateral ECC (n = 24, additional cannulation of pulmonary artery and left atrium and lungs perfused and ventilated during bypass) or conventional CPB (n = 10, right atrial and aortic cannulation, lungs statically inflated to 4 mbar (0.41 cm H(2)O) with oxygen, 500 mL/min). Determinations of ETV (thermodye dilution technique) and intraoperative fluid balance were made before surgery, at the end of surgery, and 4 hours thereafter. In addition, interleukin (IL)-8, thromboxane B2 (TxB(2)), and endothelin (ET)-1 concentrations were measured in the right atrium and pulmonary vein at specified time points. RESULTS: Comparisons of ETV made at the start of surgery, after aortic declamping, and after termination of ECC, respectively, revealed an increase from 4.8 +/- 0.2 mL/kg (mean +/- SEM) to 6.7 +/- 0.4 mL/kg, and 6.3 +/- 0.3 mL/kg with conventional CPB but ETV remained unchanged at 5.2 +/- 0.3 mL/kg, 5.1 +/- 0.2 mL/kg, and 4.9 +/- 0.3 mL/kg with bilateral ECC. Priming volume (1,580 +/- 10 mL versus 2,213 +/- 77 mL, p < 0.001) and intraoperative fluid balance (+1,955 +/- 233 mL versus +2,654 +/- 210 mL, p < 0.05) were less with conventional CPB. Concentrations of IL-8, TxB(2), and ET-1 were not different between groups. CONCLUSIONS: Despite a significantly greater prime volume and a more positive intraoperative fluid balance, ETV did not change with bilateral ECC but increased with conventional CPB. Thus, using the patient's lungs as an oxygenator during bypass mitigates the increase in extravascular pulmonary fluid.     

Disadvantages of prostacyclin infusion during cardiopulmonary bypass: a double-blind study of 50 patients having coronary revascularization

Prostacyclin (PGI2) has been suggested for use in cardiopulmonary bypass (CPB) because of its positive effects on platelet number and function. Fifty patients who underwent coronary artery bypass grafting using a bubble oxygenator received heparin, 3 mg per kilogram of body weight, and then were randomly assigned to receive PGI2, 25 ng/kg/min, beginning 5 minutes before and until the end of CPB (26 patients) or a placebo (24 patients). Both groups were similar in sex, age, heparin dose, protamine dose, and CPB time. During CPB, mean arterial pressure fell significantly with PGI2 (76 +/- 2 mm Hg to 53 +/- 2 mm Hg; p less than 0.05) and necessitated pressor substances. Platelet counts fell significantly in both groups with the start of CPB, but after 60 minutes were similar in both groups (118 +/- 9 X 10(3) versus 130 +/- 8 X 10(3); not significant [NS]) and were unchanged 3 hours after CPB. Total chest tube output was 647 +/- 51 ml (placebo group) versus 576 +/- 34 ml (PGI2 group) (NS); 18 of the patients given PGI2 required 26 transfusions compared with 16 transfusions in 8 of the patients given a placebo (p less than 0.05). In PGI2 patients, arterial oxygen tension on 100% oxygen fell from 281 +/- 18 mm Hg before CPB to 223 +/- 17 mm Hg immediately after CPB (p less than 0.05). The placebo patients did not show a change in this variable.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sequential Myocardial Depressant and Nondepressant Anaesthesia for Coronary Artery Surgery

Patients undergoing coronary artery surgery run a certain risk of developing myocardial infarction in situations with increased myocardial oxygen demand due to e.g. elevations in heart rate and blood pressure. After cardiopulmonary bypass (CPB) there is, however, also the risk of graft occlusion. The present study evaluated the haemodynamic effects of a sequential anaesthesiological technique using halothane 0.5-1.5% in combination with 50% nitrous oxide and droperidol 0.1 mg X kg b.w.-1 before CPB followed by fentanyl 0.2 mg X h-1 in continuous i.v. infusion and diazepam 10-15 mg during and after bypass. Fourteen patients were studied. In seven patients (Group I) halothane was discontinued immediately before CPB and in the following seven patients (Group II) 10-15 min before bypass. The aim was to depress moderately the inotropic state before bypass and to have a normalized myocardial oxygen demand after CPB in order to promote a good flow in the grafts. In Group II mean left ventricular stroke work index (LVSWI) was 0.54-0.79 J X m-2 after bypass as compared to 0.45-0.51 before at comparable filling pressure. Mean left ventricular power index (LVPI) increased from 0.42-0.55 W X m-2 before to 0.73-1.08 after CPB. The patients in Group I showed a similar pattern although with a less marked difference in LVSWI and LVPI values before and after bypass. No correlation was seen between oxygen delivery and oxygen uptake either below or above an oxygen delivery of 15 mmol X min-1 X m-2.     

Effect of C1-esterase-inhibitor on capillary leak and inflammatory response syndrome during arterial switch operations in neonates

OBJECTIVE: To determine if prophylactic administration of C1-esterase-inhibitor would have a beneficial effect on postoperative weight gain and the inflammatory response in neonates undergoing cardiac surgery with cardiopulmonary bypass (CPB). DESIGN: Randomized, double-blinded study. SETTING: University-affiliated heart center. PARTICIPANTS: Twenty-four neonates with transposition of the great arteries. INTERVENTIONS: In group inhibitor (INH) patients (n = 12), 100 IU/kg of C1-esterase-inhibitor (Berinert) was given 30 minutes before CPB. In group placebo (P) patients (n = 12), placebo was administered instead. Interleukin (IL)-6, C3a anaphylatoxin, C1 activity, prekallikrein, Hageman factor, D-dimers, and clinical parameters were measured 6 times perioperatively. MEASUREMENTS AND MAIN RESULTS: All 24 patients had an uneventful clinical course. Mean arterial pressure and pulmonary oxygenation after CPB were superior in group INH patients. The weight gain on postoperative days 1 to 4 was significantly less in group INH patients compared with group P (55 +/- 59 g vs. 340 +/- 121 g, day 1). The concentration of IL-6 (76 +/- 17 pg/mL vs. 262 +/- 95 pg/mL during CPB) was significantly lower in group INH patients compared with group P patients. In contrast, no influence on C3a anaphylatoxin and coagulation factors was found. CONCLUSION: Prophylactic application of C1-esterase-inhibitor in neonates undergoing arterial switch operations produces less inflammatory response compared with placebo. This difference may have contributed to improved clinical parameters, including less weight gain postoperatively.     

Failure of autologous fresh frozen plasma to reduce blood loss and transfusion requirements in coronary artery bypass surgery

BACKGROUND: Previous studies failed to demonstrate any benefit from prophylaxis with fresh frozen plasma (FFP) after cardiopulmonary bypass (CPB). The results, however, were limited by either retrospective study design or use of FFP in subtherapeutic doses (2-3 units). The authors evaluated whether a therapeutic dose (15 ml/kg) of FFP reduces blood loss and transfusion requirements in elective coronary artery bypass surgery. The risks of multiple allogeneic blood donor exposure were circumvented by using autologous plasma. METHODS: Sixty adult patients scheduled for elective primary coronary artery bypass grafting were randomized to receive, after CPB, an intravenous infusion of 15 ml/kg of either autologous FFP (30 patients) or 6% hydroxyethyl starch 450/0.7 (HES; 30 patients). Autologous plasma was obtained by platelet-poor plasmapheresis several weeks before surgery. Perioperative blood transfusions were administered per protocol. Postoperative blood loss was defined as the chest tube drainage during the first 24 h after surgery. RESULTS: The data from 56 patients (FFP group, 27 patients; HES group, 29 patients) who completed the study according to protocol were analyzed. Median postoperative blood loss was 630 ml (range, 450-1,840 ml) and 830 ml (range, 340-1,980 ml) in the FFP and HES groups, respectively (P = 0.08). Both postoperative (0-24 h) and total perioperative erythrocyte transfusion requirements did not differ significantly between the groups (P = 0.32 and 0.14, respectively). CONCLUSION: The prophylactic administration of a therapeutic dose (15 ml/kg) of autologous FFP after CPB failed to reduce blood loss and transfusion requirements in patients undergoing uncomplicated, elective, primary coronary artery bypass surgery.     

Influence of angiotensin-I-converting-enzyme insertion/deletion gene polymorphism on perioperative hemodynamics after coronary bypass graft surgery

AIM: The angiotensin I-converting enzyme insertion/ deletion polymorphism (ACE-I/D), including three genotypes (II, ID, DD), with a known impact on midterm mortality and morbidity in patients after coronary artery bypass graft surgery (CABG), was studied. Since this polymorphism has been linked with increased vascular response to phenylephrine during cardiopulmonary bypass (CPB), we investigated its possible effect on perioperative hemodynamics in patients undergoing CABG. METHODS: Genotyping for the ACE-I/D was performed by polymerase chain reaction (PRC) amplification in 110 patients who underwent elective CABG with CPB. Patients were assigned to two groups according to their genotype (group II [II genotype] and group ID/DD [ID and DD genotypes]). Systemic hemodynamics were measured directly before and at 4 h, 9 h, and 19 h after CPB. RESULTS: Genotype distribution of ACE-I/D was 18%, 57%, and 25% in genotypes II, ID, and DD, respectively. The two groups were similar in age (group II: 66+/-6 years, group ID/DD: 66+/-8 years), body-mass-index (BMI) (group II: 28+/-2, group ID/DD: 29+/-5 kg/m2), male: female ratio (group II: 16: 4, group ID/DD: 63: 27) and Euroscore (group II: 3.1+/-1.9, group ID/DD: 3.5+/-2.1). There were no differences in mortality rate or perioperative systemic hemodynamics. The pulmonary vascular resistance before cardiopulmonary bypass was higher in the ID/DD genotypes than in the II genotypes (227+/-121 vs 297+/-169 dyn.s(-1).m2.cm(-5)). Four hours after CPB no difference remained; at 9 h after cardiopulmonary bypass there was a slight difference in pulmonary vascular resistance between the two groups (247+/-134 vs 290+/-117 dyn.s(-1).m2.cm(-5)) and a significant difference in pulmonary arterial pressure (19+/-6 vs 23+/-8); at 19 h after CPB the differences were no longer detectable. CONCLUSION: ACE-I/D had no influence on perioperative systemic hemodynamics. However, transitory differences in pulmonary hemodynamic were observed after CPB. These differences may have been due to changes in serum ACE activity during CPB.     

Inhaled nitric oxide reduces pulmonary vascular resistance more than prostaglandin E(1) during heart transplantation

Heart transplantation in patients with increased pulmonary vascular resistance is often associated with postbypass right heart failure. We therefore compared the abilities of prostaglandin E(1) (PGE(1)) and inhaled nitric oxide to reduce pulmonary vascular resistance during heart transplantation. Patients undergoing orthotopic heart transplantation for congestive heart failure were randomly assigned to either a PGE(1) infusion at a rate of 8 ng. kg. (-1)min(-1) starting 10 min before weaning from cardiopulmonary bypass (CPB) (n = 34) or inhalation of 4 ppm nitric oxide starting just before weaning from CPB (n = 34). Both treatments were increased stepwise, if necessary, and were stopped 6 h postoperatively. Hemodynamic values were recorded after the induction of anesthesia, 10 and 30 min after weaning from CPB, and 1 h and 6 h postoperatively. Immediately after weaning from CPB, pulmonary vascular resistance was nearly halved in the nitric oxide group but reduced by only 10% in the PGE(1) group. Pulmonary artery pressure was decreased approximately 30% during nitric oxide inhalation, but only approximately 16% during the PGE(1) infusion. Six hours after surgery, pulmonary vascular resistance and pulmonary artery pressure were similar in the two groups. The ratio between pulmonary vascular resistance and systemic vascular resistance was significantly less in the nitric oxide patients at all postbypass times. In contrast, the pulmonary-to-systemic vascular resistance ratio increased approximately 30% in the patients given PGE(1). Cardiac output, heart rate, mean arterial pressure, right atrial pressure, and pulmonary wedge pressure did not differ between the groups. Weaning from CPB was successful in all patients assigned to nitric oxide inhalation; in contrast, weaning failed in six patients assigned to PGE(1) (P = 0.03). IMPLICATIONS: Nitric oxide inhalation selectively reduces pulmonary vascular resistance and pulmonary artery pressure immediately after heart transplantation which facilitates weaning from cardiopulmonary bypass.     

A comparison of lactated ringer's solution to hydroxyethyl starch 6% in a model of severe hemorrhagic shock and continuous bleeding in dogs

In this randomized, controlled study in dogs, we examined the short-term effects of blood pressure targeted fluid resuscitation with colloids or crystalloids solutions on systemic oxygen delivery, and lactate blood concentration. Fluid resuscitation using hydroxyethyl starch (HES) 6% to a mean arterial blood pressure (MAP) of 60 mm Hg was compared with lactated Ringer's solution (LR) to a MAP of 60 or 80 mm Hg (LR60 and LR80, respectively). The model was one of withdrawal of blood to a MAP of 40 mm Hg through an arterial catheter that was then connected to a system allowing bleeding to occur throughout the study whenever MAP exceeded 40 mm Hg. Target MAP was maintained for 60 min with a continuous infusion of the designated fluid replacement. All 15 dogs (5 in each group) survived until the last measurement. Blood loss in the LR80 group (2980 +/- 503 mL) (all values mean +/- SD) was larger than in the LR60 and HES60 groups (1800 +/- 389 mL, and 1820 +/- 219 mL, respectively) (P < 0.001). Whereas 840 +/- 219 mL of HES60 was needed to maintain target MAP, 1880 +/- 425 mL of LR was needed in the LR60 group, and 4590 +/- 930 mL in the LR80 group (P < 0.001). Lactate blood concentrations were smaller and delivered O(2) higher in the HES60 group (35 +/- 17 mg/dL and 239 +/- 61 mL/min, respectively) in comparison to the LR60 group (89 +/- 18 mg/dL and 140 +/- 48 mL/min, respectively) and the LR80 group (75 +/- 23 mg/dL and 153 +/- 17 mL/min, respectively) (P = 0.02 and P = 0.026). In conclusion, fluid resuscitation during uncontrolled bleeding, to a target MAP of 60 mm Hg, using HES60 resulted in larger oxygen delivery and smaller systemic lactate A resuscitation to a target MAP of 60 or 80 mm Hg using LR. IMPLICATIONS: Fluid resuscitation to a target mean arterial blood pressure of 60 mm Hg during uncontrolled bleeding resulted in larger oxygen delivery and smaller systemic lactate concentrations when hydroxyethyl starch 6% was used, in comparison to lactated Ringer's solution resuscitation to a target mean arterial blood pressure of 60 or 80 mm Hg.     

Does sodium nitroprusside reduce lung injury under cardiopulmonary bypass?

Objective: We hypothesized that direct pulmonary arterial infusion of sodium nitroprusside (SNP) would ameliorate lung injury under cardiopulmonary bypass. Methods: Experiments were performed on 12 adult mongrel dogs of both sexes weighing 20–28 kg. The animals were randomly divided into two groups of six animals each. All animals were subjected to total cardiopulmonary bypass (CPB) and moderate hypothermia (28°C core temperature). During total CPB, the aorta was clamped together with the pulmonary artery to prevent any antegrade flow to the lungs. After cardioplegic arrest for 120 min, the animals were rewarmed, weaned from CPB, and their condition stabilized for another 90 min. After the release of the aortic cross-clamp, the dogs received either a 5% glucose solution as a placebo (group I) or SNP (0.5 μg/kg per min) (group II), both infused into the pulmonary arterial line. The infusion was stopped after 60 min. To measure lung tissue malondialdehyde (MDA), water content and polymorphonuclear leukocytes count, lung tissue samples were taken before CPB and after weaning from CPB. In addition, alveolar-arterial oxygen difference (AaDO₂) for tissue oxygenation was calculated by obtaining arterial blood gas samples. Results: Values of MDA before CPB of 42.0±5.3 nmol/g of tissue rose to 67.6±5.7 nmol/g of tissue after weaning from CPB in group I (P=0.028). In group II MDA values also increased from 43.1±4.3 to 52.4±5.7 nmol MDA/g of tissue after weaning from CPB (P=0.046). The MDA increase in group II after CPB was found to be significantly lower than that for group I (P=0.004). The wet-to-dry lung weight ratio in the sodium nitroprusside group was 5.1±0.2, significantly lower than in the control group (6.8±0.4), (P=0.01). AaDO₂ increased significantly in group I (P=0.028). There was no statistically significant difference (P=0.065) between groups I and II. During histopathological examination it was observed that neutrophil counts in the lung parenchyma rose significantly after CPB in both groups. The increase in group I was significantly larger than that in group II (P<0.001). Conclusions: The results represented in our study indicate that pulmonary arterial infusion of sodium nitroprusside during reperfusion can reduce lung injury under cardiopulmonary bypass.