Safety and utility of modified ultrafiltration in pediatric cardiac surgery.

INTRODUCTION: Modified ultrafiltration (MUF) is employed at the termination of cardiopulmonary bypass (CPB) in pediatric and neonatal patients undergoing congenital heart surgery to reduce the accumulation of total body water thus increasing the concentration of red blood cells and the other formed elements in the circulation. Modified ultrafiltration has been reported to remove circulating pro-inflammatory mediators that result in systemic inflammatory response syndrome (SIRS) postoperatively. METHODS: Four hundred patients undergoing cardiac surgery requiring cardiopulmonary bypass and weighing less than or equal to 12 kg were retrospectively evaluated for the effectiveness of MUF. After the termination of CPB, blood was withdrawn through the aortic cannula and passed through a hemoconcentrator attached to the blood cardioplegia set and returned to the patient through the venous cannula. The entire CPB circuit volume in addition to the patient's circulating blood volume were concentrated until the hematocrit value displayed on the CDI cuvette within the MUF circuit reached 45% or there was no more volume to safely remove. At the same time a full unit of FFP can be infused as water is being removed, thus maintaining euvolemia. RESULTS: MUF was performed in all 400 patients with no MUF-related complications. Following the conclusion of MUF, anecdotal observations included improved surgical hemostasis, improved hemodynamic parameters, decreased transfusion requirements, and decreased ventilator times. CONCLUSIONS: Complete MUF enables the clinician to safely raise the post-CPB hematocrit to at least 40% while potentially removing mediators that could result in SIRS. In addition a full unit of FFP can be administered while maintaining euvolemia.

Unique static discharge events on two CentriMag® (2nd Gen) ECMO patients causing console failure.

The use of ECMO for cardiovascular support continues to increase in the United States and around the world. It is not a benign endeavor as serious complications may occur. We present our experience of two second generation CentriMag® (Abbott formerly Thoratec Inc.) console failures that occurred while transporting the patients to other areas of the hospital. In each incident, the patients were immediately placed on back-up units and the transport continued. No patient complications could be attributed to the failures. An investigation by Abbott engineers traced the failure to a static build-up and discharge caused by a non-manufacturer-approved metal rod that was utilized to mount the external monitor. The static discharge caused a disruption of electrical continuity between the control system and the motor, stopping the motor as well as the monitoring system. Removal of the mounting rod prevented replication of the situation in the lab. We have removed the rod from our clinical units and have not experienced any other pump failures.

In Vitro Comparison of Two Neonatal ECMO Circuits Using a Roller or Centrifugal Pump With Three Different In-Line Hemoconcentrators for Maintaining Hemodynamic Energy Delivery to the Patient.

The objective of this study was to compare three different hemoconcentrators (Hemocor HPH 400, Mini, and Junior) with two different neonatal ECMO circuits using a roller or a centrifugal pump at different pseudo-patient pressures and flow rates in terms of hemodynamic properties. This evidence-based research is necessary to optimize the ECMO circuitry for neonates. The circuits used a 300-mL soft-shell reservoir as a pseudo-patient approximating the blood volume of a 3 kg neonate, two blood pumps, and a Quadrox-iD Pediatric oxygenator with three different in-line hemoconcentrators (Hemocor HPH 400, Mini, and Junior). One circuit used a Maquet H20 roller pump and another circuit used a Maquet RotaFlow centrifugal pump. The circuit was primed with lactated Ringer's solution followed by heparinized packed red blood cells with a hematocrit of 40%. The pseudo-patient's pressure was manually maintained at 40, 60, or 80 mm Hg and the flow rate was maintained at 200, 400, or 600 mL/min with a circuit temperature of 36°C. Pressure and flow data was recorded using a custom-made data acquisition device. Mean pressures, diverted blood flow, pressure drops, and total hemodynamic energy (THE) were calculated for each experimental condition. The roller pump and centrifugal pump performed similarly for all hemodynamic properties with all experimental conditions. The Hemocor HPH Junior hemoconcentrator added the highest resistance to the circuit. The Hemocor HPH Junior provided the highest circuit pressures, lowest diverted blood flow, highest pressure drop across the circuit, and highest THE generated by the pump. The Hemocor HPH 400 added the least resistance to the circuit, providing the lowest circuit pressures, more diverted flow, lowest pressure drop, and the lowest THE generated by the pump. However, the THE delivered to the patient was the same for the three hemoconcentrators. While the three hemoconcentrators performed differently in terms of hemodynamic properties throughout the circuit, the THE transmitted to the patient was similar for all three hemoconcentrators due to the consistent pseudo-patient's pressure that was manually maintained for each trial. While the THE delivered to the patient indicates similar perfusion for these patients with any of the three hemoconcentrators, the differences in added resistance to the circuit may impact the decision of which hemoconcentrator is used. There was no clinically significant difference between the two circuits with the roller versus centrifugal pump in terms of hemodynamic properties in this study. Further in vivo research is warranted to confirm our findings.

Comparison of hemolysis between CentriMag and RotaFlow rotary blood pumps during extracorporeal membrane oxygenation.

The purpose of this investigation was to compare the hemolysis levels for patients on extracorporeal membrane oxygenation (ECMO) incorporating two different rotary blood pumps (CentriMag [CMAG] and RotaFlow [RF]) in identical circuits otherwise. The difference between the two pumps is the cost. One is 20-30 times less expensive than the other. A retrospective analysis of all patients placed on ECMO from June 2008 through May 2012 was done to evaluate hemolysis. Daily plasma hemoglobin (pHb), lactate dehydrogenase (LDH), and lactate levels were collected on all patients. Values were compared between those patients who received a CMAG and those who received an RF. Patients had to be on ECMO for more than 2 days to be included in the study. Linear mixed effects models were fit to the data to assess differences over time for each continuous outcome. Forty patients were placed on ECMO incorporating CMAG, whereas 40 patients received an RF. There were no significant statistical differences between CMAG and RF groups when comparing days on support (8.7 ± 5.0; 8.4 ± 5.7), age (44.8 ± 18.3; 46.1 ± 16.0), body surface area (2.03 ± 0.36; 1.96 ± 0.31), gender (male: 58%, female: 42%; male: 55%, female: 45%), etiology, type of support (veno-arterial [VA)]: 78%, veno-venous [VV)]: 22%; VA: 82%, VV: 18%) and pre-ECMO LDH levels (4004.0 ± 3583.2; 3603.7 ± 3354.1). There were also no significant differences between the CMAG and RF groups when comparing the mean values for daily pHb levels (5.7 ± 3.6; 5.7 ± 4.2), lactate levels (2.8 ± 1.9; 3.0 ± 2.1), and LDH levels (2656.3 ± 1606.8; 2688.6 ± 1726.1) or daily lactate, LDH, and pHb levels for the first 10 days of support. From our investigation, there is no difference between the CMAG and the RF blood pumps in regard to the creation of hemolysis during ECMO. The difference in cost of the devices does not correlate with the performance and outcomes.

The new role of the perfusionist in adult extracorporeal life support.

Adult and pediatric extracorporeal life support (ECLS) has been transformed by the European(1) and Australian( 2) experiences with a reduction of the circuit to its most basic form (Figure 1). Many factors have converged at this point in time to allow us to offer this support. The availability in the U.S.A. of an advanced oxygenator (Quadrox(D)) (Maquet Inc., Bridgewater, NJ), long-term centrifugal pumps and circuit coatings offers us the means to provide ECLS. The other equally important factor is the intensivist trained in extracorporeal therapies. Once the intensive care unit registered nurse (ICU RN) is trained to safely and effectively manage both the patient and ECLS circuit, this support may be offered. The perfusionist is in an unique position to educate and mentor the ICU RN in ECLS. There is, perhaps, no one in a better position to explain this equipment and its uses in an interdisciplinary-oriented pediatric and adult ECLS program than a perfusionist.

Perfusion safety: defining the problem.

Perfusion safety is not an isolated component of cardiac surgery, but encompasses many facets, including equipment, safety devices, conduct of perfusion, surgical technique, vigilance, and communication within the operating room. Over the last 25 years, several surveys have provided an estimation of the occurrence of perfusion-related incidents and documented the frequency with which they affected patient morbidity and mortality. As the focus of attention turned to correcting these problem areas, each subsequent survey demonstrated changes, but also pointed out new areas needing improvement. As technology and education improved, so did results. With refinements in perfusion equipment and techniques, and increasing use of computer assistance and automation, cardiopulmonary bypass should become even safer. The key ingredient, though, will remain the knowledge and expertise of the perfusionist.

Conventional approach to glucose management for diabetic patients undergoing coronary artery bypass surgery.

Continuous insulin infusion was not an effective mode of treatment in maintaining safe blood glucose levels (<200 mg/dl) during the intraoperative period of diabetic patients requiring open-heart surgery. The two modifications investigated to gain better control of the blood glucose were a change in the base solution of the cardioplegia and the use of a sliding insulin scale. Fifty patients including Type I and Type II diabetics were selected for the purpose of this study. The patients were then randomly divided into two groups categorized by the type of cardioplegic solution administered and the mode of insulin treatment. Group I patients received a dextrose 5%-based cardioplegic solution and blood glucose was treated via continuous intravenous insulin infusion. Group II patients received normal saline 0.9%-based cardioplegic solution and blood glucose was treated via sliding scale. Blood glucose levels were monitored pre- and postcardiopulmonary bypass (CPB) and every 30 min while on CPB. Glucose values were analyzed by group t test. A p value of <0.05 was considered statistically significant. When comparing Group I (mean=258 mg/dl) with Group II (mean=158 mg/dl), there was a statistically significant difference between the glucose values at each of the time intervals when the glucose values were recorded. In conclusion, Group II maintained an acceptable blood glucose level (<200 mg/dl) throughout the entire intraoperative period, which suggests that the combination of the sliding insulin scale and modification of the base cardioplegic solution was an effective mode of treatment.

A comparison of several variables of off-pump coronary artery bypass procedures versus myocardial revascularization utilizing cardiopulmonary bypass.

An investigation was conducted to compare several variables of off-pump coronary artery bypass (OPCAB) procedures with those using cardiopulmonary bypass (CPB) for myocardial revascularization by two surgeons. The patients were divided into four groups: group 1 patients received CPB for their myocardial revascularization performed by surgeon A; group 2 patients received the OPCAB procedure performed by surgeon A; group 3 patients received CPB for their myocardial revascularization performed by surgeon B; and group 4 received the OPCAB procedure performed by surgeon B. The same anesthesia technique and postoperative management were employed for all patients in this study. The CPB procedures received the same perfusion circuit and conduct. Postoperative laboratory values, including hemoglobin, hematocrit and platelet counts for the OPCAB groups, were higher than the CPB groups. Chest tube drainage was similar for both the OPCAB and CPB groups, but postoperative urine outputs were significantly higher in the CPB groups for both surgeons. Positive fluid balance was statistically greater in the CPB groups compared to the OPCAB groups for both surgeons. Ventilator times, length of stay in the intensive care unit (ICU) and length of hospital stay were not statistically significant for the groups in this study. Postoperative weight gain for both surgeons was higher in the CPB groups. Intraoperative packed red blood cell (PRBC) usage for surgeon B was similar for both the OPCAB and CPB groups, but the OPCAB group for surgeon A had greater intraoperative PRBC usage than the CPB group.