An update on perfusion safety: does the type of perfusion practice affect the rate of incidents related to cardiopulmonary bypass?

Cardiopulmonary bypass (CPB) techniques vary among adult and pediatric patients undergoing cardiac surgery. This may result in a differential conduct of CPB between various aged patients. The present study reports on perfusion incidents occurring in hospitals using extracorporeal circulation. An 80 question survey was mailed to chief perfusionists at all 1030 US cardiac surgical centers. Respondents were asked to report on device use and incidents occurring during a 2-year period from July 1996 to June 1998. Five hundred and twenty-four completed surveys were returned with the age of surgical patients operated on at each hospital defined as either an adult (n=407), pediatric (n=17), or combined-adult and pediatric (n=100). Centrifugal pumps were used as the primary systemic pumps in 54% of adult, 12% of pediatric, and 36% of combined centers. In-line blood gas monitoring was used in 76% of all pediatric hospitals, but in only 30% of adult facilities. Incident rates occurred once per every 120.9, 83.9, and 220.2 cases in adult, pediatric, and combined centers, respectively. Mortality rates related to CPB occurred 2.7 times higher in adult and pediatric centers as compared to combined hospitals. Arterial dissection was the number one cause of death in both pediatric and combined hospitals, while coagulation disturbances resulted in the highest mortality for adult procedures. Results of this study show that the lowest incident rates occur at hospitals performing combined adult and pediatric CPB.

Factors affecting perfusionists' decisions on equipment utilization: results of a United States survey.

The decision to utilize extracorporeal equipment is influenced by a number of factors, including clinical efficacy, cost effectiveness, and personal judgment. The purpose of this study was to report the results of a national survey that examined factors affecting perfusionists' decisions on equipment utilization. An 80-question survey was mailed to chief perfusionists at 1030 U.S. hospitals performing open-heart surgery. 524 completed surveys were returned, which represented 797 hospitals (78.8%) and 671,290 procedures over a 2-year period (July 1996-June 1998). Within the survey, 36 questions pertained to equipment utilization and served as the basis for this report. The perfusion equipment that had seen the greatest reduction in use were; heparin-coated circuits (HCC) (12.0%), in-line blood gas monitors (9.7%), soft-shell venous reservoirs (SSVR) (7.2%), and in-line arterial hemoglobin monitors (6.3%). Cost was the major determinant affecting the decision for the following devices: in-line blood gas monitors (82.4%), cardioplegia in-line delivery filters (75.0%), in-line arterial hemoglobin monitors (69.7%), HCC (55.6%), and SSVR (43.2). Ineffectiveness was the major reason reported for discontinuation of arterial-line bubble traps (64.7%), venous reservoir level detectors (50.0%), and arterial-line pressure manometers with pump shutdown (50.0%). 438 respondents discontinued use of one or more of 29 different devices during the past 2 years. Cost was the major reason in 52.7% of the cases, ineffectiveness in 33.1%, and 14.2% were in a category labeled "other." The pressures brought upon by the changing healthcare structure have influenced perfusionists' equipment selection, with cost being a major factor affecting clinical decisions for certain device utilization.

A retrospective study on perfusion incidents and safety devices.

Despite the acceptance of extracorporeal circulation as an effective modality to facilitate cardiac surgery, patient outcomes can be negatively influenced by the occurrence of perfusion incidents. A perfusion survey was conducted to identify safety techniques and incidents related to cardiopulmonary bypass (CPB). An 80-question survey was mailed to chief perfusionists of all 1030 USA cardiac surgical centers using CPB. The survey was designed to examine practices and incidents that occurred during a 2-year period (July 1996 to July 1998). Five-hundred-and-fifty-two (54% response rate) surveys were returned, which accounted for 797 hospitals (79% of all cardiac centers) and 653,621 surgical procedures. Of the 27 identified CPB safety devices, the highest utilization was arterial line filters (98.5%) and the lowest arterial line bubble traps (3.4%). Of the reported cases, a CPB incident occurred once every 138 cases. The most common occurring incidents were protamine reactions (1:783), coagulation problems (1:771), and heater/cooler failures 11:1809). The rate of occurrence of an incident resulting in a serious injury or death was one for every 1453 procedures. Although techniques and safety devices create a relatively secure environment for CPB, lower incident rates may be achieved with further improvements in coagulation monitoring and incident reporting.

Co-administration of aprotinin and epsilon-aminocaproic acid during cardiopulmonary bypass in a swine model.

Despite the beneficial effects of pharmacological interventions to prevent bleeding and to reduce the need for autogeneic blood, there are concerns that these agents induce a prothrombotic state. The purpose of this study was to examine the coagulation phenomena influenced by the coadministration of epsilon-aminocaproic acid (EACA) and aprotinin during cardiopulmonary bypass (CPB). A swine model of CPB was utilized in this study. During 120 min of CPB, treatment animals (N = 5) received 6 x 10(6) Kiu of aprotinin and 30 grams of EACA; whereas, control animals (N = 3) received an equal volume of 0.9% saline. Indices of thrombogenicity included hematological variables, gross pathology, and circuit examination for the presence of thrombus. The application of both antifibrinolytics resulted in an increase use of heparin. Total heparin requirements were significantly different between treatment group (58,800 +/- 3493 iu) versus control group (51,000 +/- 3464 iu). D-dimer concentration was also significantly higher in the control group (500-1000 ng mL-1) than in the treatment group (250-500 ng mL-1) at 5 and 30 min postprotamine. Other coagulation markers tested were not observed to be statistically significant between groups. Thromboelastographic (TEG) index decreased in the treatment group during the surgical procedure and bypass from 2.74 +/- 2.9 to -1.36 +/- 4.1 as compared to an increase from 2.62 +/- 2.9 to 4.05 +/- 0.4 in the control group. Pathologic analysis revealed occurrences of thrombus formation in small vessels in the lung and kidney glomeruli of treatment animals. The concurrent use of both aprotinin and EACA may induce a prothrombotic or coagulant state as determined by histological assessment.

The effects of nitric oxide on coagulation during simulated extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) is associated with profound alterations in hemostasis, with platelet dysfunction often being implicated as a causative factor for transfusion. Nitric oxide (NO) has shown to be a rapid yet temporary inhibitor of platelet function. The purpose of this study was to evaluate the effects of NO on platelet number and function in an in vitro ECMO model. Eight silicone membrane oxygenators were primed with fresh, heparinized, bovine blood and allowed to circulate for 48 hours. The treatment group (NO) consisted of four oxygenators that had an end concentration of 20 ppm NO applied to the sweep gas. Platelet counts, methemoglobin levels, plasma-free hemoglobin levels, activated clotting times, and thromboelastographic (TEG) studies were performed at baseline, 1, 6, 12, and 24 h. Scanning electron microscopy (SEM) was performed on sample areas from each oxygenator. The treatment group maintained an average of 25% higher platelet counts than the control group (85.1 +/- 32.0, x 10(3) versus 66.5 +/- 30.9 x 10(3)) although statistical significance was not achieved. Methemoglobin levels were significantly elevated in the treatment circuit at hours 12 and 24 (p < .05). This could be attributed to the lack of a biological interaction that would break down this toxic by-product. TEG indices steadily declined in both groups from baseline (-0.4 +/- 3.6) to (-17.2 +/- 3.3 p < .0007) treatment and (-20 +/- 4.5, p < .0001) control, with the treatment circuit maintaining only slightly improved indices over the most of the study. SEM data showed increased fibrin and cellular deposits in the control group (p = .05) when compared with the treatment group. NO added to the sweep gas of a simulated ECMO circuit at 20 ppm had little effect on the maintenance of platelet number and function.

An in vitro evaluation of a self-contained cardioplegia delivery device.

Focus on improved myocardial protection has prompted the development of delivery systems which can accommodate the demands of increasingly refined cardioprotective strategies. The purpose of this study was to evaluate the Sorin Blood Cardioplegia Console (BCC) for accuracy and precision in the delivery of cardioplegia solutions. An in vitro model was designed to evaluate the following performance characteristics of the BCC: delivery volume (blood and crystalloid) at 50, 250, 375, and 500 ml/min flow rates; potassium end-delivery concentration at blood:crystalloid ratios of 4:1, 8:1, and 16:1; intermittent cardioplegia delivery; and heat transfer of the internal heater/cooler. Differences in blood and cardioplegia volumes between measured and calculated values across all flow rates tested were found to be statistically significant and ranged from 1.4 to 21.5 ml; however, the differences were within the accepted variance of the instrument (+/- 5%). Across all tested ratios, the measured end-potassium concentrations were all within 1 mEq of the expected values, except for the 16:1 ratio at 50 ml/min, which had a 2.52 mEq variance. All significant differences were within the accepted variance of the instrument (+/- 5%). In conclusion, the BCC accurately and delivered cardioplegia volumes and potassium concentrations across all tested conditions with reproducible performance.