A comparison of anaesthetic tensions in arterial blood and oxygenator exhaust gas during cardiopulmonary bypass

This study evaluates the usefulness of the analysis of gas sampled from the exhaust port of a membrane oxygenator in the estimation of anaesthetic tension in arterial blood. Sixty-seven arterial blood samples were drawn from patients undergoing hypothermic cardiopulmonary bypass with anaesthesia maintained by either isoflurane or desflurane. Anaesthetic tensions in the oxygenator exhaust gas were measured using an infrared analyser and in arterial blood using a two-stage headspace technique with a gas chromatograph. Both measurement systems were calibrated with the same standard gas mixtures. There was no difference in anaesthetic tension measured in arterial blood and gas leaving the oxygenator exhaust (isoflurane: n = 29, range: 0.3-0.8%, 95% limits of agreement: -0.08% to 0.09%; desflurane: n = 38, range: 1.5-5.4%; 95% limits of agreement -0.65% to 0.58%). We conclude that anaesthetic tensions in arterial blood can be accurately monitored by analysis of the gas emerging from the exhaust port of a membrane oxygenator.     

Urethral blood circulation during cardiopulmonary bypass

The haemodynamic changes induced by extracorporeal circulation (ECC) are thought to be important in the induction of urethral strictures in open heart surgery when indwelling latex catheters are used. In the present study, 6 piglets were cannulated and connected to extracorporeal perfusion apparatus. Pump flows correlated with human ECC values with non-haemic prime were used. The mucosal and submucosal blood circulation in the urethra reduced by 66% during ECC (P less than 0.05). The brain and hepatic arterial flows increased. A significant reduction was seen in renal blood circulation. The changes in the urethral blood circulation during ECC correlated with previous findings. The reduced wash out levels of chemicals leaching from the indwelling latex catheters as a result of reduced local blood circulation are the main trigger for the induction of urethral strictures during ECC and in other shock-like circulatory disturbances in the human body.     

A comparative study of cardiopulmonary bypass with nonblood and blood prime

A prospective study of cardiopulmonary bypass in adult cardiac surgical patients undergoing similar types of operations compared 50 consecutive perfusions utilizing a clear, balanced, electrolyte-protein prime with 50 consecutive perfusions utilizing a solution containing 1,000 ml. of blood. Significant findings were: The oxygenation and perfusion capabilities during bypass were similar and satisfactory in both groups. The postoperative coagulation studies were essentially the same. The postoperative plasma hemoglobin was 83 mg. per 100 ml. with nonblood prime and 138 mg. per 100 ml. with blood prime; and 12 hour postoperative blood loss was 353 ml. with nonblood prime and 455 ml. with blood prime—22% less in the nonblood prime group. Total blood requirements during hospitalization averaged 1,500 ml. in the nonblood prime group and 3,500 ml. in the blood prime group.The use of nonblood prime and autotransfusions reduces postoperative blood loss, demands on blood bank facilities, risk of serum hepatitis, transfusion reactions, and coagulation abnormalities.     

Priming solutions for cardiopulmonary bypass: comparison of three colloids

The present study was designed to compare the differences in the clinical effects of three colloidal solutions, albumin, urea-linked gelatin, and succinyl-linked gelatin, when used as priming fluids for cardiopulmonary bypass (CPB) under alpha-stat conditions. A consecutive series of 105 patients scheduled for cardiac surgery were randomized into three identically managed groups, except for the CPB prime. Variables relating to acid-base status, oncotic activity, metabolism, coagulation, and postoperative evaluation were measured. Marked differences in acid-base status, colloid osmotic pressure, additional prime requirements, blood lactate, urine output, and the need for buffer solutions occurred among groups, with the succinyl-linked gelatin group having better results than the other groups. Changes in hemodynamics, oxygen consumption, and blood-glucose levels during CPB did not vary among groups. There were also no important intergroup differences in hematologic and clotting variables or postoperative parameters such as blood loss or use of blood products. Electrolyte changes were similar except for a significant increase in ionized calcium that occurred in the urea-linked gelatin group after bypass. The results indicate that succinyl-linked gelatin is an adequate and safe alternative to human albumin for use as a colloid during CPB under alpha-stat conditions.     

A comparison of low vs conventional-dose heparin for minimal cardiopulmonary bypass in coronary artery bypass grafting surgery

The biocompatibility of minimal extracorporeal circuits has improved; however, anticoagulation is still required. We compared standard high-dose anticoagulation with a low-dose heparin regimen in a retrospective study of patients who underwent coronary bypass surgery using minimal cardiopulmonary bypass. One hundred patients who received 300 IU.kg(-1) heparin were compared with 68 patients who received heparin according to an individually adjusted activated coagulation time target of 300 s, resulting in a mean (SD) heparin dose of 145 (30) IU.kg(-1) . There were no thromboembolic events in either group; however, patients in the low-dose group had lower 24-hour mean (SD) postoperative blood loss than the conventional group (545 (61) vs 680 (88) ml, p=0.001) and a reduced rate of transfusion of allogeneic blood (15% patients transfused vs 32%, p=0.01). An individually tailored low-dose heparin regimen for minimal cardiopulmonary bypass is safe and may be associated with reduced bleeding and lower transfusion requirements.     

A prospective, randomized study of cardiopulmonary bypass temperature and blood transfusion

BACKGROUND: We hypothesized that normothermic cardiopulmonary bypass (CPB) would be associated with decreased blood loss and allogeneic transfusion requirements relative to hypothermic CPB. METHODS: After obtaining institutional review board approval and informed patient consent, we conducted a prospective, randomized study of 79 patients undergoing CPB for a primary cardiac operation at normothermic (37 degrees C) (n = 44) or hypothermic temperature (25 degrees C) (n = 35). Blood loss and transfusion requirements in the operating room and for the first 24 hours in the intensive care unit were determined. A paired t test and rank sum tests were used. A p value of less than 0.05 was considered significant. RESULTS: The normothermic and hypothermic CPB groups did not differ in demographic variables, CPB or cross-clamp duration, heparin sodium or protamine sulfate dose, prothrombin time, or thromboelastogram results. There were no differences between the two CPB groups in blood loss or transfusion requirements. CONCLUSIONS: We found that when there was no difference in duration of CPB, normothermic and hypothermic CPB groups demonstrated similar blood loss and transfusion requirements even though other studies have shown hypothermia induces platelet dysfunction and alters the activity of the coagulation cascade.     

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.     

Effective hepatic blood flow during cardiopulmonary bypass

Hepatic dysfunction following cardiopulmonary bypass (CPB) is a relatively frequent finding, and jaundice occurring after CPB is associated with an increased mortality rate. Post-CPB jaundice may be a consequence of inadequate liver perfusion during CPB. To evaluate the potential impact of CPB on effective hepatic blood flow, 10 patients undergoing CPB for cardiac procedures were studied. Effective hepatic blood flow was measured in each patient during the operative procedure but before institution of CPB and during CPB as well. Effective hepatic blood flow was measured by the galactose clearance technique. Blood lactate and pyruvate levels were also measured before and during CPB. During CPB, effective hepatic blood flow was consistently reduced by an average of 19%. Although for most patients this reduction seems well tolerated, in a minority of patients it may contribute to postoperative hepatic dysfunction.     

Coronary artery bypass grafting by warm blood cardioplegia and normothermic cardiopulmonary bypass

Warm blood cardioplegia and normothermic cardiopulmonary bypass (CPB) have been used in coronary artery bypass grafting (CABG). The method of myocardial protection was intermittent combined antegrade and retrograde warm blood cardioplegia with terminal warm blood cardioplegia. We performed elective CABG in 30 patients above the age of 70 years (elderly group). These patients were compared with 30 patients below 70 years who underwent elective CABG (young group). No significant differences were observed about the preoperative data between two groups. No significant differences were obtained in the postoperative cardiac function, cerebral or renal complication between two groups. Warm blood cardioplegia and normothermic CPB were not associated with adverse effects on postoperative recovery in elderly as well as young patients. We may conclude that warm blood cardioplegia with normothermic CPB is a safe procedure for CABG in elderly as well as young patients.     

A technique for separation of perfluorocarbons from blood used in cardiopulmonary bypass laboratory procedures

Eliminating from physiologic circulation a significant amount of unnecessary perfluorocarbons (PFC) is advantageous since little is known about long-term effects of PFC in the circulatory system. The basic circuitry, cell-washer, mechanical manipulations, and overall concept revealed that a significant amount of PFC can be retrieved and estimated in volume and compared to initial volumes. A method of separating a certain PFC blood substitute from blood following laboratory cardiopulmonary bypass is described.     

An ultrafiltration technique for directly reinfusing residual cardiopulmonary bypass blood

Given the shortages of banked blood, the risks of transfusion reactions, disease transmissions, and transfusion errors, we perfusionists must find ways to avoid blood transfusions. At the end of any given bypass run, there is residual blood left in the bypass circuit, the perfusionist must get this blood back to the patient. Most commonly either a cell saver or a hemoconcentrator (HC) has been used, in some fashion, to reinfuse residual circuit blood. The ideal method should: 1) be simple; 2) raise the hematocrit (HCT); 3) allow for changes in the patient's volume status; and 4) not compromise the integrity of the cardiopulmonary bypass (CPB) circuit allowing for rapid re-institution of CPB. We describe a technique in which residual CPB circuit blood is pumped through an HC directly to the patient via a 3/16-inch diameter line into a 16-gauge intravenous needle positioned in a peripheral or central vein. This allows the perfusionist to give back concentrated blood that is protein-rich while maintaining the above criteria.     

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.     

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.     

A reusable training circuit for cardiopulmonary bypass

At the turn of the millennium, perfusion teaching programs are faced with significant difficulties. The number of students in pediatric perfusion training has increased, and more importantly, the number of pediatric open-heart procedures has decreased because of a variety of reasons. Hence, they could barely satisfy the minimum requirements of pediatric cases established by the teaching programs. The idea of "a teaching circuit" that could reproduce and simulate cardiopulmonary bypass was designed. The trainee is able to manipulate the cardiopulmonary bypass circuit according to patient responses, to perform perfusion related-maneuvers in establishing and maintaining hemodynamic stability. The aim of this study was to simulate a patient on CPB, maintain stability during varying clinical situations, and then to wean the patient off CPB. The equipment used was reusable and nonsterile.