Extracorporeal Life Support Group Research Articles

Extracorporeal circulatory systems in the interhospital transfer of critically ill patients: experience of a single institution

BACKGROUND AND OBJECTIVES:Critically ill patients with acute circulatory failure cannot be moved to other institutions unless stabilized by mechanical support systems. Extracorporeal heart and lung assist systems are increasingly used as a bridge to end-organ recovery or transplantation, and as an ultimate rescue tool in cardiopulmonary resuscitation.PATIENTS AND METHODS:From July 2001 to April 2008, we had 38 requests for extracorporeal support for interhospital transfer carried out by the air medical service. Respiratory failure was present in 29 patients, who were provided with pumpless extracorporeal lung assist (PECLA) or veno-venous extracorporeal membrane oxygenation (ECMO). Cardiac failure dominated in 9 patients, who underwent implantation of extracorporeal life support (ECLS). Underlying diseases were acute respiratory distress syndrome in 15 patients, pneumonia in 7, prior lung transplant status in 4, cardiogenic shock in 7, and septic shock in 4.RESULTS:All assist systems were connected via peripheral vessels by the Seldinger technique. Transport was uneventful in all cases with no technical failures. On arrival at the specialized care hospital, two patients had leg ischemia and underwent relocation of the arterial cannula. After a mean (SD) support of 5.1 (3.0) days for PECLA, 3.5 (2.9) days for ECLS, and 7.3 (5.8) days for ECMO, 60%, 66%, and 66% of patients, respectively, could be successfully weaned from the systems. Discharge rates were 45% for PECLA, 44% for ECLS, and 56% for ECMO.CONCLUSION:Our experience proves that minimized extracorporeal assist devices allow safe assistance of patients with isolated or combined heart and lung failure in need of interhospital transfer. Critically ill patients get a chance to reach a center of maximum medical care.

Comparison of Myocardial Loading Between Asynchronous Pulsatile and Nonpulsatile Percutaneous Extracorporeal Life Support

We hypothesized that myocardial loading can be increased when extracorporeal pulse flow occurs during systole, and that this may adversely affect myocardial working conditions in heart failure patients supported by extracorporeal life support (ECLS). This study was designed to compare myocardial loading and myocardial oxygen consumption/supply balance between nonpulsatile ECLS and asynchronized pulsatile ECLS in a myocardial stunning model. Thirteen, 23-42 kg dogs were allotted to a nonpulsatile group and an asynchronous pulsatile group. Coronary sinus lactate level, mixed venous oxygen consumption (MvO2), and left anterior descending coronary artery flow were measured. The real-time pressure of the left ventricle and the ascending aorta was monitored, and the lowest left ventricular pressure and tension time index were calculated. Our results showed that the lactate level and the lowest left ventricular pressure were lower in the pulsatile group than in the nonpulsatile group at 30 minutes after ECLS was applicated (p < 0.05, respectively). Tension time index in the pulsatile ECLS group was substantially lower than in the nonpulsatile group. Left anterior descending coronary flow did not show significant difference between the two groups. In conclusion, asynchronous pulsatile ECLS may also be superior to nonpulsatile ECLS in myocardial volume unloading and oxygen consumption/supply balance.

Do critically ill surgical neonates have increased energy expenditure?

Adult metabolic studies suggest that critically ill patients have increased energy expenditures and thus require higher caloric allotments. To assess whether this is true in surgical neonates the authors utilized a validated, gas leak-independent, nonradioactive, isotopic technique to measure the energy expenditures of a stable postoperative group and a severely stressed cohort. Eight (3.46+/-1.0 kg), hemodynamically stable, total parenteral nutrition (TPN)-fed, nonventilated, surgical neonates (5 with gastroschisis, 2 with intestinal atresia, and 1 with intestinal volvulus) were studied on postoperative day 15.5+/-11.9. These were compared with 10 (BW = 3.20+/-0.2 kg), TPN-fed, extracorporeal life support (ECLS)-dependent neonates, studied on day of life 7.0+/- 2.8. Energy expenditure was obtained using a primed, 3-hour infusion of NaH(13)CO(3'), breath (13)CO(2) enrichment determination by isotope ratio mass spectroscopy, and the application of a standard regression equation. Interleukin (IL)-6 levels and C-reactive protein (CRP) concentrations were measured to assess metabolic stress. Comparisons between groups were made using 2 sample Student's t tests. The mean energy expenditure was 53+/-5.1 kcal/kg/d (range, 45.6 to 59.8 kcal/kg/d) for the stable cohort and 55+/-20 kcal/kg/d (range, 32 to 79 kcal/kg/d) for the ECLS group (not significant, P =.83). The IL-6 and CRP levels were significantly higher in the ECLS group (29 +/-11.5 v 0.7+/-0.6 pg/mL [P<.001], and 31+/-22 v 0.6+/-1.3 mg/L [P<.001], respectively). Mortality rate was 0% for the stable postoperative patients and 30% for the ECLS group. Severely stressed surgical neonates, compared with controls, generally do not show increased energy expenditures as assessed by isotopic dilution methods. These data suggest that the routine administration of excess calories may not be warranted in critically ill surgical neonates and support the hypothesis that neonates obligately redirect energy, normally used for growth, to fuel the stress response. This is a US government work. There are no restrictions on its use.

Effect of extracorporeal life support on survival when applied to all patients with congenital diaphragmatic hernia

Extracorporeal life support (ECLS) has been used for neonates with congenital diaphragmatic hernia (CDH) and respiratory failure at the authors' hospital since June 1981. In 1988, criteria for inclusion in ECLS were broadened to include “nonhoneymoon” infants (honeymoon: best postductal Pa o 2 of > 50 mm Hg). To evaluate the impact of this approach on the treatment of CDH, the authors reviewed the records of all newborns managed at their institution, since the availability of ECLS in 1981, who were symptomatic with CDH in the first 24 hours of life (n = 111). The patients were divided chronologically into two groups: 1981 to 1987 (early ECLS, n = 36) and 1988 to 1993 (expanded ECLS, n = 75). The data demonstrate that the number of CDH patients managed at our institution each year has increased (1981 to 1987 = 6, 1988 to 1993 = 14) as has the severity of associated respiratory insufficiency (% of patients with best Pa o 2 of ≤ 50 mm Hg: 1981 to 1987 = 6%, 1988 to 1993 = 28%). Overall, the survival rate was lower for patients in the expanded ECLS group (59% v 75%; P = .121). When the survival rates for patients supported with ECLS postoperatively were compared for the expanded and early groups, a significant difference (59% v 80%; P < .05) was noted. However, when ECLS patients with a best Pa o 2 of ≤ 50 mm Hg were excluded from this analysis, there was no significant difference between the two groups (74% v 80%), indicating that the inclusion of nonhoneymoon patients as potential ECLS candidates has accounted for a significant portion of the observed decrease in survival among CDH patients managed with ECLS. The survival rate of salvageable CDH patients with a best Pa o 2 of ≤ 50 mm Hg increased slightly for the expanded ECLS group, to 27% (4 of 15), versus 0% (0 of 2) for the early ECLS group. The authors conclude that a change in the population of CDH patients presenting to their institution along with application of ECLS to CDH patients without a honeymoon has resulted in a reduction in the survival rate, but has allowed only a modest 27% survival rate for patients who were previously considered nonsalvageable.

Large volume instillation of surfactant during extracorporeal life support improves lung function in lung lavaged rabbits.

The sometimes limited effect of surfactant therapy in neonates might be explained in part by an non homogeneous distribution of the surfactant after endotracheal instillation. This distribution can be improved significantly by increasing the fluid volume. The aim of this study was to evaluate the effect of two methods for gas exchange during a large volume instillation of surfactant on the outcome of this treatment in lung lavaged rabbits. In the control group (n = 6) gas exchange was maintained with continuous positive pressure ventilation (CV), whereas in the other group gas exchange was established with extracorporeal life support (ECLS) (n = 6) and intermittent sighs. Five hours after surfactant administration, an identical weaning procedure was started in both groups. The authors found significantly higher PaO2 values in the ECLS group than in the control group in the normocarbia state. All animals in the ECLS group could be weaned to room air maintaining normal blood gases, whereas all the animals in the control group died in the course of weaning. The ventilator efficiency index was significantly higher during the weaning period in the ECLS group, indicating better lung function, than in the control group. The authors conclude that a large volume instillation of surfactant is feasible by applying ECLS and intermittent sighs. Additional studies are needed to elucidate if this combined treatment will be an improvement over current surfactant therapy.