Clinical comparison of three different anaesthetic depth monitors during cardiopulmonary bypass

The lack of a gold standard complicates the evaluation and comparison of anaesthetic depth monitors. This randomised study compares three different depth-of-anaesthesia monitors during cardiopulmonary bypass (CPB) at 34 degrees C with fentanyl/propofol anaesthesia adjusted clinically and blinded to the monitors. Coronary artery bypass grafting patients (n = 21) were randomly assigned to all three possible paired combinations of three monitors: Bispectral Index (Aspect Medical), AAI auditory evoked potential (Danmeter), Entropy (Datex-Ohmeda). Indices were manually recorded every 5 min during CPB. Agreement between paired indices was classified as good, non-, or disagreement. Anaesthesia was classed as adequate, inadequate, or excessive according to recommended index values. Of the 255 paired indices recorded, 62% showed good agreement, 33% showed non-agreement, and 5% showed disagreement. Using good agreement between two monitors as a gold standard, a quarter of the measurements indicate inappropriate anaesthetic depth monitoring during CPB with clinically titrated anaesthetic depth.     

A prospective comparison of three heat preservation methods for patients undergoing hypothermic cardiopulmonary bypass

OBJECTIVE: To prospectively compare 3 methods of body heat preservation in patients undergoing surgery requiring the use of hypothermic cardiopulmonary bypass (CPB). DESIGN: Prospective, randomized, and nonblinded. SETTING: University teaching hospital. PARTICIPANTS: Adult cardiac surgery patients (n = 101). INTERVENTIONS: Subjects were randomly assigned to 1 of 3 treatment groups: Group 1 (n = 33) used a fluid-filled warming blanket, group 2 (n = 31) used a heated and humidified breathing circuit, and group 3 (n = 37) used intravenous fluid warmers for the administration of all fluids. Treatments started on separation from CPB and concluded at the end of the intraoperative experience. Anesthetic technique, minute ventilation, conduct of CPB, and room temperature in the operating room were standardized. MEASUREMENTS AND MAIN RESULTS: Blood temperature was measured at its nadir on CPB, on separation from CPB, and just before departure from the operating room. No differences were found among groups for CPB duration, coldest venous temperature on CPB, rewarming time, rate of rewarming, room temperature, or blood temperature on separation from CPB. There were no significant differences found in post-CPB temperature afterdrop among groups. CONCLUSIONS: This study suggests that there is no statistically significant disparity in the effectiveness of these 3 intraoperative heat preservation methods. Ease of use and cost-effectiveness should guide the choice of warming method post-CPB.     

A comparison of blood and Fluosol-DA for cardiopulmonary bypass

Fluosol-DA was compared to blood as a pump prime for total cardiopulmonary bypass in the pig animal model. Nineteen pigs weighing between 14 and 22 kg were studied, nine with blood and ten with Fluosol. Metabolic and hemodynamic measurements were determined before, during and after 60 minute bypass to establish the adequacy of Fluosol to sustain perfusion as compared to blood. The measurements and subsequent calculations included blood gases, arterial and mixed venous oxygen content, oxygen extraction and consumption, cardiac output, systemic and pulmonary vascular resistance and arterial, venous, pulmonary artery and left atrial pressures. The result showed a significant decrease in hematocrit during bypass in the Fluosol group as compared to blood perfusion (20 vs. 30%). While the arterial oxygen content fell from control levels with Fluosol during bypass, in the blood prime group, oxygen content remained at pre-control levels. Whole body oxygen consumption decreased during bypass, in both groups equally, but this decrease did not lead to acidosis and was stable during recovery. Oxygen and carbon dioxide transport were adequately maintained during bypass in both Fluosol and blood groups. Systemic pressures remained stable during bypass and were lower, but stable, during recovery. Pulmonary vascular resistance was elevated in both groups during recovery which probably explains a concomitantly decreased cardiac output. There was a 40% mortality in both experimental groups secondary to postpump pulmonary hypertension. It is concluded that Fluosol is a satisfactory oxygen carrying agent to be used instead of blood during cardiopulmonary bypass, and in the pig model both blood and Fluosol were associated with a high incidence of pulmonary hypertension.     

The inflammatory response to colloids and crystalloids used for pump priming during cardiopulmonary bypass

Background: Systemic inflammatory response frequently occurs after coronary artery bypass surgery and is strongly correlated with the risk of postoperative morbidity and mortality. This study tests the hypothesis that the priming of the extracorporeal circuit with colloid solutions results in less inflammation in patients undergoing cardiac surgery than priming with crystalloid solutions. Methods: A prospective, randomized study was designed. Forty‐four patients undergoing elective coronary artery bypass grafting were randomly allocated to one of two groups: 22 patients primed with Ringer's lactate (RL) solution and 22 patients primed with gelatin‐containing solution during the surgery. Plasma levels of interleukin (IL)‐6, IL‐8, tumor necrosis factor (TNF)‐α, C‐reactive protein (CRP) and, complement 4 were measured during the surgical intervention and over the following 48 postoperative hours. Cytokine levels were measured by enzyme‐linked assays from plasma samples obtained at specific time points pre‐ and post‐operatively. Results: In both groups the serum levels of the pro‐inflammatory cytokines (IL‐6, IL‐8, TNF‐α), CRP, complement 4, and leukocytes increased significantly over the baseline, although no significant differences were observed between the two groups. The operation time, blood loss, need for inotropic support, extubation time, and length of intensive care unit stay did not differ significantly between the two groups. Conclusion: Priming with gelatin vs. RL produces no significant differences in the inflammatory response in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass.     

Coronary artery bypass grafting with and without cardiopulmonary bypass: a comparison analysis

Coronary artery bypass grafting (CABG) using stabilization devices in place of the heart-lung machine is being performed on a wide range of patients. This study retrospectively compared the performance of off-pump coronary artery grafting bypass (OPCAB) with conventional bypass patients over the same 6-month period at The Medical University of South Carolina. Data were collected and compared from the National Cardiac Database of the Society of Thoracic Surgeons (STS). Parameters studied included age, gender, left ventricular ejection fraction (LVEF), previous myocardial infarction (MI), disease severity, number of grafts, complications, blood usage, ventilation times, operating room (OR) time, and hospital length of stay (LOS). There were no significant difference between the patient groups with regard to age, gender, LVEF, previous MI, predicted mortality, and LOS. Operative mortality was also similar in the two groups: conventional bypass 4/117 (3%) and OPCAB 2/86 (2%). The conventional bypass patients (CPB) had significantly (p < 0.05) more diseased vessels (2.9 vs. 2.6) and distal grafts (4.1 vs. 2.7), as compared to the OPCAB group. OPCAB procedures resulted in significantly (p < 0.05) lower mean OR time (365 min vs. 406 min) and reduced mean postoperative ventilation hours (3.4 vs. 8.3 hours), as compared to conventional bypass. There were significantly (p < 0.05) fewer blood transfusions in the OPCAB group (1.1 units vs. 2.4 units), and the percentage of patients transfused blood was significantly less (34.9% vs. 57.3%). Nine out of 95 (9.5%) of patients who presented for OPCAB were converted to conventional bypass. Although there may be potential benefits to OPCAB, further studies must be directed at determining those patients who would benefit most from CABG using the off-pump technique.     

Reoperative coronary bypass surgery using normothermic cardiopulmonary bypass: comparison with first-time procedures.

Redo coronary artery bypass grafting (CABG) is characterized by increased patient risk compared with first-time CABG. The reason for higher risk is not completely understood but it is logically related to inadequate myocardial preservation evidenced by the higher incidence of postoperative low-output syndrome. We compared normothermic cardiopulmonary bypass with cold blood maintenance cardioplegia in both first-time and redo CABGs to determine whether this single approach is appropriate for both instances. Five hundred seventeen consecutive CABG patients were retrospectively reviewed. Four hundred fifty-four first-time CABG procedures were compared with 44 redo procedures. All aspects of the operation were identical including myocardial preservation. Retrospective univariant analysis of both groups followed. Three clinical features distinguished first-time versus redo CABG. These were previous percutaneous transluminal coronary angioplasty (first-time 19% vs redo 71%; P < 0.001), preoperative intra-aortic balloon pump (first-time 38% vs redo 71%; P < 0.001), and Parsonnet risk score (first-time 11.7+/-8.2 vs redo 19.2+/-8.8; P < 0.001). Operative mortality for redo CABG was higher than in first-time procedures (3.4% vs 6.4%; P = not significant), although small sample size limited statistical significance. The length of stay was statistically longer in redo patients (8.7+/-10.8 vs 6.0+/-5.1 days; P < 0.01) and is related to a higher Parsonnet score, increased postoperative pneumonia, and failed percutaneous transluminal coronary angioplasty before redo CABG. We conclude that redo CABG is a different operation from first-time procedures and requires enhanced myocardial preservation. Normothermic cardiopulmonary bypass with cold blood maintenance cardioplegia does not appear to achieve this goal.     

Superior results of ketone body ratio in pulsatile normothermic cardiopulmonary bypass; comparison with non-pulsatile cardiopulmonary bypass

Sixteen patients undergoing aortocoronary bypass surgery under normothermic cardiopulmonary bypass were divided into 2 groups according to the either addition or none of pulsatility induced by intra-aortic balloon pumping (IABP). In those patients, hepatic blood flow was measured 3 times before, during and after cardiopulmonary bypass. Additionally, arterial and hepatic ketone body ratios [(AKBR) and (HKBR)], and hepatic venous saturation (ShvO2) were measured throughout and after the surgery. RESULTS: The hepatic blood flows measured at 3 different times at the surgery were much more in the pulsatile group (p < 0.05). The values of AKBR, indicator of mitochondrial redox potential in hepatocytes, were maintained in nearly normal in the pulsatile group, but were suppressed in the non-pulsatile group. This trend was much more obvious in the values of HKBR. The significantly lower ShvO2 levels were observed in the non-pulsatile group during the cardiopulmonary bypass (p < 0.05). CONCLUSIONS: Pulsatile normothermic cardiopulmonary bypass induced by IABP provides better liver perfusion and results in a better hepatic metabolism than non-pulsatile cardiopulmonary bypass.     

Hydroxyethyl starch versus albumin in cardiopulmonary bypass prime solutions

To compare hydroxyethyl starch (HES) with 25% albumin, 20 patients undergoing aortocoronary bypass were randomized into two groups: 10 received 1,000 ml of HES and 10 received 200 ml of 25% albumin in a bloodless priming solution for cardiopulmonary bypass (CPB). Platelet aggregation, antithrombin III, reptilase time, fibrinogen, plasminogen, fluid requirements, and hemodynamics were monitored. Platelet aggregation was abnormal in both groups, being relatively poorer in the albumin group. Both groups exhibited below normal antithrombin III and plasminogen levels, with significantly lower antithrombin III levels noted in the HES group postoperatively (41.9 +/- 11.8% versus 56.6 +/- 9.9%; p = 0.006). Compared with the albumin group, the HES group had slightly, but not significantly, elevated liver function test results, total volume replacement (9,173 +/- 2,046 ml versus 8,522 +/- 1,192 ml; p = 0.057), packed red blood cell usage (227 +/- 284 ml versus 75 +/- 168 ml; p = 0.066), and chest tube drainage (599 +/- 253 ml versus 454 +/- 174 ml; p = 0.144). In the HES group, 5% albumin requirement was greater (386 +/- 466 ml versus 50 +/- 158 ml; p = 0.002) and percent increase of body weight was higher (5.2 +/- 0.8% versus 2.3 +/- 0.6%; p = 0.05) postoperatively. Postoperative weight increase and colloid requirements plus trends toward larger blood loss and blood transfusions indicate possible further evaluation. However, results suggest that HES is a safe additive to priming solutions. Compared with albumin, HES has comparable changes in coagulation variables and slightly less severe derangements in platelet aggregation.     

Comparison of three methods to estimate heparin loading dose for cardiopulmonary bypass

Three available methods used to determine heparin loading dose were studied to determine the most reliable method for reaching a target pre-bypass activated clotting time (ACT) of 510 seconds. One hundred and seven patients were randomly assigned to one of three treatment methods: A) 300 units/kg; B) Hemostasis Management System (HMS); C) RX/DX. Five different lots of heparin were assigned to Groups A and B, and Group C had one heparin lot. Different lots were used to account for possible variations in heparin activity. Post-skin incision ACTs, post-heparin pre-bypass ACTs, and heparin loading doses were compared. The mean and standard deviation of the post-heparin pre-bypass ACTs were used to determine which method was most reliable to obtain a desired ACT. There was no statistical difference between different heparin lots. There was no difference in the post-heparin ACTs for the three methods (A:487 +/- 135 vs. B:474 +/- 105 vs. C:474 +/- 111 sec). There was a statistically significant difference between the standard deviation for the HMS and 300 u/kg standard deviations (p < 0.05). The HMS has the smallest deviation which makes it the most reliable predictor of heparin loading doses to reach a target ACT for cardiopulmonary bypass.     

Minimally invasive direct coronary bypass versus cardiopulmonary technique: angiographic comparison

BACKGROUND: Studies comparing minimally invasive direct coronary artery bypass grafting (MIDCABG) with techniques using cardiopulmonary bypass (CPB) are needed. METHODS: Sixteen patients underwent single-vessel left internal thoracic artery-left anterior descending (LITA-LAD) MIDCABG through a left anterior thoracotomy, and 10 underwent multivessel bypass grafting that included a LITA-LAD, using CPB. Intraoperative completion angiography was performed on all LITA-LAD bypasses, and graded. One point each was given for: anastomotic patency, pedicle patency, intercostal obliteration, proper placement into the correct native coronary artery, and Thrombosis In Myocardial Ischemia grade III flow. RESULTS: There were no intraoperative deaths or morbidities. LITA takedown averaged 49 +/- 18.6 minutes for MIDCABG and 16 +/- 2.0 minutes for CPB CABG (p < 0.05). LITA length did not differ between groups (15.3 +/- 1.2 cm for MIDCABG, 14.3 +/- 1.08 cm for CPB CABG). Ischemic arrest time was significantly less for the CPB group (13.3 +/- 8.3 minutes versus 24.5 +/- 9.6 minutes; p < 0.05). Average grade for MIDCABG LITA-LAD was 4.06 +/- 0.98 points versus 4.77 +/- 0.98 points for CPB LITA-LAD bypass (p = not significant). CONCLUSIONS: Intraoperative completion angiography is feasible and, when combined with a grading system, may facilitate the comparison of MIDCABG with standard techniques.     

Hematologic derangements of cardiopulmonary bypass: a comparison of two perfusion systems

A major goal of new perfusion equipment is minimal trauma to blood elements. This study compares two perfusion systems, quantifies the change in blood components and generation of microemboli, as well as compares the hospital courses of each perfusion system. Forty-four coronary patients were assigned to either Group S, a silicone rubber membrane (SciMed) and centrifugal pump (Bio-Medicus) (N=19) or Group C (our routine equipment), a microporous polypropylene membrane (COBE CML) and roller pump (COBE) (N=25). The rise in plasma hemoglobin (26+/-14mg* in Group S and 26+/-17mg* in Group C), the drop in hematocrit (-15.0+/-3.9* in Group S and -14.7+/-3.8* in Group C at the second post-op day), and the decrease in platelet count (-152,000+/-78,000* in Group S and -129,000+/-52,000* in Group C) were similar in both groups. There was no difference in rise in post-op alveolar-arterial oxygen gradients or debris generated by each system. 27.7% in Group S required red cell transfusions and only 8% required red cell transfusions in Group C. There was no significant difference in clinical endpoints such as ICU stay, hospital stay and complication rate. We found no advantage to more expensive perfusion devices and no improvement upon the extensive CPB damage to formed blood elements. * p less than .001     

Neuropsychological dysfunction after cardiopulmonary bypass: a comparison of two institutions.

The authors compared perioperative neuropsychologic dysfunction in patients participating in two studies conducted in institutions using different strategies to manage cardiopulmonary bypass. These differences included hypothermia versus normothermia, presence versus absence of arterial microfilters, and the presence versus absence of glucose-containing solution in the pump prime. Other differences between the two institutions included the type of surgery (intracardiac v extracardiac), the mean duration of cardiopulmonary bypass, and degree of low perfusion pressure during bypass. Despite these major differences, perioperative neuropsychologic dysfunction measured by the two-part Trail-Making psychometric test was similar in the two institutions. Several factors were analyzed for their possible contribution to development of dysfunction, including institution, anesthetic management, age, sex, degree of low perfusion pressure during bypass, and duration of bypass; only age was significant. These results suggest that differences in surgical procedure and management of cardiopulmonary bypass previously thought to contribute to the development of subtle cognitive deficits after cardiac surgery may have been overemphasized.     

Cardiopulmonary bypass: new strategies for weaning from cardiopulmonary bypass

This review focuses on weaning from cardiopulmonary bypass, a very critical time for patients and anaesthetists and frequently requiring major therapeutic effort. Few novel strategies for weaning have been described recently. Most drugs or approaches described during the review period are already well established. Emphasis is placed on the importance of non-cardiac factors, and on the importance of diastolic ventricular function as opposed to systolic function.     

Beating heart versus conventional cardiopulmonary bypass: the octopus experience: a randomized comparison of 281 patients undergoing coronary artery bypass surgery with or without cardiopulmonary bypass

In the Octopus Study, 281 coronary artery bypass surgery patients were randomized to surgery with or without cardiopulmonary bypass. The primary objective was to compare cognitive outcome between off-pump and on-pump coronary artery bypass surgery. Before and after surgery, psychologists administered a battery of 10 neuropsychological tests to the patients. Cognitive decline was defined as a decrease in an individual's performance of at least 20% from baseline, in at least 20% of the main variables. According to this definition, cognitive decline was present in 21% in the off-pump group and 29% in the on-pump group, 3 months after the procedure (P = .15). At 12 months, cognitive decline was present in 31% in the off-pump group and 34% in the on-pump group (P = .69). These results indicated that patients undergoing coronary artery bypass surgery without cardiopulmonary bypass had improved cognitive outcomes 3 months after the procedure, but the effects were limited and became negligible at 12 months. The same definition of cognitive decline was also applied to 112 volunteers not undergoing surgery. The definition labeled 28% of the control subjects as suffering from cognitive decline, 3 months after their first assessment. This suggests that the natural fluctuations in performance during repeated neuropsychological testing should be included in the statistical analysis of cognitive decline. Using an alternative definition of cognitive decline that takes these natural fluctuations in performance into account, the proportions of coronary artery bypass surgery patients displaying cognitive decline were substantially lower. This indicates that the incidence of cognitive decline after coronary artery bypass surgery has been overestimated.     

Comparison of Ringer's acetate and lactate solutions as a prime for cardiopulmonary bypass

Nineteen patients undergoing myocardial revascularization were randomly given either Ringer's lactate or acetate solution as the prime of cardiopulmonary bypass (CPB), and systemic vascular resistance (SVR) was determined before, and for 10 minutes after, the commencement of CPB. There were no significant differences in SVR or perfusion pressure between the acetate or lactate groups before or during CPB. Blood gas and acid-base values, haematocrit, serum potassium, sodium and ionized calcium concentrations as well as patient temperature were similar in the two study groups. Our results are at variance with some previous experimental findings, which have suggested that acetate has a greater vasodilative effect than lactate.     

Hydroxyethyl starch as a prime for cardiopulmonary bypass: effects of two different solutions on haemostasis

Hydroxyethyl starch (HES) is efficacious as a volume expander in cardiac surgical patients, but it may impair the haemostatic mechanisms. However, this latter effect may be less conspicuous with low molecular weight (LMW) solutions than with high molecular weight (HMW) solutions. Therefore, LMW– and HMW–HES solutions were evaluated as priming solutions for cardiopulmonary bypass (CPB) with respect to their effect on haemostasis. Forty–five patients undergoing coronary bypass grafting were prospectively randomised to three groups and in a double–blind manner as their CPB prime either 20 ml kg^-1 LMW–HES (M_w 120 000), 20 ml kg^-1 HMW–HES (M_w 400000) or Ringer's acetate 2000 ml. The final volume of the prime was completed to 2000 ml with Ringer's acetate in the HES groups. Anaesthesia and CPB management were standardised. Plasma levels of von Willebrand factor antigen and factor VIII procoagulant activity were significantly more depressed after CPB in both HES–groups as compared with the crystalloid prime group. In addition, APTT was more prolonged and the maximal amplitude of thromboelastographic tracing was more decreased in the HES–groups. It is concluded that it may be advisable to avoid HES solutions in the CPB prime, especially in patients with an increased risk for bleeding after cardiac operations.     

Clinical comparison of pulsatile and nonpulsatile perfusion during cardiopulmonary bypass

Controversy exists concerning the utilization of pulsatile flow during cardiopulmonary bypass (CPB) with regard to improved patient outcomes. The purpose of the present study was to evaluate pulsatile perfusion in patients undergoing CPB in a clinical setting. Seventy patients undergoing open heart surgery for repair of valvular or congenital heart disease were prospectively entered into the study and were randomly assigned to either pulsatile perfusion (PP, n = 35) or nonpulsatile perfusion (NP, n = 35) groups. All patients received identical surgical, perfusion, and postoperative care. Study parameters included: rate of spontaneous cardiac conversion, inotropic drug use, urine output, skin temperature, platelet count, fibrinogen concentration, and plasma free hemoglobin level. There were no statistically significant differences seen in either preoperative or operative parameters between groups. The PP group had a significantly higher rate of spontaneous cardiac conversion, less inotropic drug use, earlier recovery of skin temperature, and higher urine output during CPB (908.8 +/- 87.2 ml/hr vs. 606.1 +/- 57.5 ml/hr, p < .01). There were no significant differences in either platelet count or fibrinogen concentration between groups. There was a steady increase in plasma free hemoglobin during PP, which was not seen in the NP group (p < .01). We conclude that the use of pulsatile flow resulted in improved patient outcomes in maintaining better renal function and preserving cardiac function in the early post-bypass period.     

不同统计学指标评价体外循环心内直视术后患者早期认知功能障碍的比较

目的 通过神经心理测验观察体外循环心内直视术前、术后患者认知功能的变化，比较不同统计学指标评价体外循环心内直视术后早期认知功能障碍的发生率，为临床应用提供参考。方法 择期体外循环心内直视术患者47例，ASAⅡ或Ⅲ级，年龄15～45岁。分别在术前第1天和术后第7天行神经心理测验。另选取健康志愿者40名，间隔7d行神经心理测验2次，作为对照，采用标准差指数（SDI）、可信改变指数（RCI）和改良可信改变指数（MRCI）评价各项测验中认知功能损害的发生率及总认知功能障碍的发生率。结果 采用SDI、RCI和MRCI判断的总认知功能障碍发生率分别为14．9％、8．5％、19．1％，差异有统计学意义（P〈0．05）。与SDI比较，视觉再生测验中RCI和MRCI评价的认知功能损害发生率降低，数字符号测验中MRCI评价的认知功能损害发生率升高（P〈0．05）；与MRCI比较，数字符号测验中SDI、RCI评价的认知功能损害发生率降低（P〈0．05）。结论 对体外循环心内直视术患者，MRCI是分析术后早期认知功能较合理的统计学指标。