The correlation of fluid balance changes during cardiopulmonary bypass to mortality in pediatric and congenital heart surgery patients.

Edema acquired during the perioperative period has long been associated with increased mortality. Edema acquired during cardiopulmonary bypass (CPB) may contribute to this mortality. The intent of this retrospective study was to test the premise that edema in the form of a positive fluid balance change (FBC) acquired during CPB correlated to mortality. If so, FBC from the beginning of CPB (baseline; FBC = 0) to the end of CPB may need to be monitored, measured, and controlled on CPB with the same ardor as blood pressure and pH. This retrospective analysis reviewed the FBC of 1540 pediatric and congenital heart surgery patients at the end of CPB. Additions and subtractions of fluid to the combined patient/CPB circuit were routinely quantified during CPB procedures and during periods of modified ultrafiltration (MUF). The primary outcome assessed was mortality during hospitalization. The overall mortality of the 1540 patients was 5.65% from all causes. Eighty percent (n = 1226, mortality = 4.65%) of the patients had a zero or negative FBC immediately after CPB/MUF. Twenty percent (n = 314, mortality = 9.55%) had a positive FBC. Positive FBC patients tended to be in higher risk categories, weighed more, and had longer pump times (p < .05) with an adjusted odds ratio for mortality of 1.73 (1.01-2.96, 95% confidence interval). There is a correlation between edema acquired during CPB and increased mortality in pediatric and congenital heart surgery patients. The potential exists for the perfusionist to optimize the fluid balance changes while on CPB to reduce mortality rates.

Identifying neonatal and pediatric cardiac and congenital diaphragmatic hernia extracorporeal membrane oxygenation patients at increased mortality risk.

UNLABELLED: A previous review from our institution established clinically measured cut-points that defined the late implementation of extracorporeal membrane oxygenation (ECMO) correlating to increased mortality in neonatal and pediatric respiratory patients. Using the same methods, this review evaluates pediatric and neonatal cardiac and congenital diaphragmatic hernia (CDH) patients to determine if the same cut-points exist in this higher risk patient population. Neonatal and pediatric cardiac and CDH patients placed on ECMO between November 1989 and December 2008 were retrospectively reviewed to determine the first adjusted anion gap (AGc), the first venoarterial carbon dioxide (CO2) gradient (p[v-a]CO2), and the first Viability Index (AGc + p[v-a]CO2 = INDEX) on ECMO. These markers were then analyzed to identify the presence of specific cut-points that marked an increased risk of mortality. The timing of surgery was also reviewed to assess the surgical morbidity on survival. The review of neonatal and pediatric cardiac and CDH patients (n = 205) with an overall survival of 46% showed that all three markers were elevated to varying degrees in the expired patients (n = 110). Histograms identified the following specific cut-points for increased mortality: the AGc > or = 23 mEq/L, the p[v-a]CO2 _ 16 mmHg, and the INDEX > or = 28. An elevated AGc and INDEX correlated with a significantly higher risk for mortality (p < .05), survival to discharge being 20% or less. Patients under the cut-points had survival rates of 51% or higher. The timing of surgery (before or after ECMO initiation) did not significantly impact survival in the combined cardiac and CDH group. An INDEX > or = 28 correlates with non-survival. We speculate that the late implementation of ECMO may lead to reperfusion injury, which causes reduced survival, and that ECMO intervention prior to reaching the cut-points may improve survival in neonatal and pediatric cardiac and CDH patients. KEYWORDS: cardiac, congenital, diaphragmatic, extracorporeal membrane oxygenation, neonate, pediatric.

Defining the late implementation of extracorporeal membrane oxygenation (ECMO) by identifying increased mortality risk using specific physiologic cut-points in neonatal and pediatric respiratory patients.

There is no reliable clinical indicator showing how long extracorporeal membrane oxygenation (ECMO) implementation can be delayed before the risk of death becomes unacceptably high in neonatal and pediatric respiratory patients. However, the late use of ECMO may be defined by the elevation of specific physiologic markers separate from pulmonary function and hemodynamic assessments that indicate when the optimal time for implementation of ECMO has past, resulting in a higher than normal mortality, possibly due to reperfusion injury. Neonatal patients were reviewed retrospectively to determine if later implementation of ECMO correlated to increased mortality. Neonatal and pediatric respiratory patients placed on ECMO were reviewed retrospectively to determine if the first adjusted anion gap (AGc), the first venoarterial CO2 gradient (p[v-a] CO2), or the first Viability Index (AGc + p[v-a]CO2 = INDEX) on ECMO could be used to identify a cut-point for increased mortality. Expired neonates (n = 31) were placed on ECMO an average of 2 days later than neonatal survivors (n = 163). The review of 210 respiratory neonatal and pediatric ECMO patients with an overall survival of 82% showed that all three markers were elevated in the expired patients (n = 38, p < .05). Cut-points were an AGc > or = 23 mEq/L, the p[v-a]CO2 > or = 16 mmHg, and the INDEX > or = 28. These values correlated with a significantly higher risk of mortality (p < .05); survival to discharge being 43% or less. Patients under the cut-points had survival rates of 84% or higher. Starting ECMO too late may cause reperfusion injury that reduces survival. This study describes specific physiologic markers taken soon after ECMO initiation that correlate with mortality. These markers, if assessed earlier, may allow for a more timely ECMO implementation and higher survival.

Evaluation of biocompatible cardiopulmonary bypass circuit use during pediatric open heart surgery.

The contact of blood with nonbiological surfaces during cardiopulmonary bypass (CPB) induces a whole body inflammatory response and increases postoperative morbidity directly related to bleeding complications and end organ dysfunction. Methods to reduce these effects have included modification of extracorporeal circuits through biocompatible coating of disposables and the application of various pharmacological agents. Biocompatible coated surfaces are designed to mimic physiologic surfaces. This study was designed to ascertain the effects of using coated circuits during pediatric CPB. After Institutional Review Board approval and parent/guardian consent, patients undergoing CPB, weighing less than 15 kg, with target CPB temperatures more than 28 degrees C, were enrolled into the Coated Circuit Group using an entirely biocompatible CPB circuit with poly(2-methoxyethylacrylate) (PMEA) and a biocompatible coated oxygenator (n = 16). Those patients were retrospectively matched to control patients having the same congenital repair with respect to patient size, surgeon, anesthesiologist, bypass time, cross-clamp time, bypass temperature, and noncoated bypass disposables; (n = 16). CPB data collected included on-bypass platelet count, hematocrit (HCT), and CPB blood product use. Postprotamine data collected in the operating room included blood product use, time from initial protamine administration to chest closure, platelet count, prothrombin time (PT), activated partial thromboplastin time (aPTT), and international normalized ratio (INR). Postoperative intensive care unit (ICU) data included blood product use, HCT, chest tube output, platelet count, PT, aPTT, INR, blood gases, lactate, and ventilator settings at 1, 2, 4, 6, 12, and 24 hours. Other data collected included intubation time, length of time to chest tube removal, and length of ICU stay. Statistical significance (p < .05) was seen in units of platelets transfused postprotamine, ventilator peak inflation pressure (PIP) on admission to the ICU, postoperative day 0 packed red blood cells (PRBC) and fresh frozen plasma (FFP) transfused, and lactate at 1, 2, 4, 6, and 12 hours postoperative. Several parameters approached statistical significance, including PRBC transfused postprotamine, time from protamine administration to chest closure, postoperative day 0 platelets transfused, and ICU stay. The data suggest that PMEA biocompatible CPB circuits can be used safely during pediatric heart surgery, resulting in a decrease in postoperative blood product use, improved postoperative lung function, and a reduction in the time spent in the ICU.

The effect of surface modification and aprotinin on cellular injury during simulated cardiopulmonary bypass.

Cardiopulmonary bypass (CPB) elicits derangements to the formed elements of blood because of the physical stresses of extracorporeal flow. Methods of reducing the impact of CPB include circuit surface modification and pharmacological supplementation. The purpose of this study was to examine the effects of aprotinin in combination with surface modification during simulated CPB. Fresh whole bovine blood was used to prime standard CPB circuits divided into four groups (N = 3): control (CTR), aprotinin 300 KIU/mL (APR), Poly (2-methoxyethylacrylate) coating (PMEA), and APR with PMEA (APR-PMEA). Physical stresses included venous reservoir negative pressure (-85 mmHg), arterial line pressure of 150 mmHg at 5 LPM, and air-blood interface, applied over a 90-minute period. Samples were drawn at the following times: 0, 10, 45, and 90 minutes. Endpoints included platelet count (PLT), plasma-free hemoglobin (PFHb), and thromboelastography (TEG). PLT did not change (138.9 +/- 15.0 vs. 102.9 +/- 21.0, p = ns) throughout the 90-minute experimental periods in any group. PFHb increased significantly (mean of 19- fold) throughout the experiment, but was not affected by any treatment. The TEG index declined in the CTR (3.6 +/- 0.4 vs. -16.2 +/- 2.9, p < .0003), PMEA (5.9 +/- 0.8 vs. -2.7 +/- 3.8, p < .02), and APR-PMEA (4.6 +/- 1.0 vs. -2.8 +/- 0.3 p < .0003) groups, but not in the APR group (3.6 +/- 2.2 vs. -1.3 +/- 3.3 p = .10). In conclusion, neither APR nor PMEA had an effect on either red cell hemolysis or PLT, but APR treatment alone significantly attenuated the derangements in coagulation induced in this extracorporeal model.