Lynne K. Bower

Use of rapid-deployment extracorporeal membrane oxygenation for the resuscitation of pediatric patients with heart disease after cardiac arrest.

INTRODUCTION We have recently used extracorporeal membrane oxygenation as a means of rapidly resuscitating pediatric patients with heart disease after cardiopulmonary arrest, in whom conventional resuscitation measures have failed. METHODS We developed a fully portable extracorporeal membrane oxygenation circuit that is maintained vacuum and carbon dioxide-primed at all times. When needed, the circuit is crystalloid-primed and can be ready for use within 15 minutes. Since February 1996, we have used this rapid-deployment circuit to resuscitate 11 pediatric patients in full cardiopulmonary arrest. RESULTS The median age of the 11 patients was 120 days (2 days to 4.6 years). Nine patients had a cardiac arrest after cardiac surgery. One patient had a cardiac arrest during cardiac catheterization and one patient had a cardiac arrest before cardiac surgery. Median duration of cardiopulmonary resuscitation was 55 minutes (range 20 to 103 minutes), with no difference in the duration of cardiopulmonary resuscitation between survivors and nonsurvivors. Ten of 11 patients (91%) were weaned from extracorporeal membrane oxygenation and seven (64%) survived to hospital discharge. Six patients are long-term survivors, five of whom are in New York Heart Association class I; one survivor is in class II. Seven patients resuscitated with extracorporeal membrane oxygenation before the use of this rapid-deployment circuit had a median duration of cardiopulmonary resuscitation of 90 minutes, with two (28.6%) survivors. CONCLUSIONS The use of rapid-deployment extracorporeal membrane oxygenation results in shorter resuscitation times and improved survival in pediatric patients with heart disease after cardiopulmonary arrest.

Aminocaproic acid decreases the incidence of intracranial hemorrhage and other hemorrhagic complications of ECMO

Since the inception of extracorporeal membrane oxygenation (ECMO), hemorrhage has been a major complication often limiting its usefulness. This study was undertaken to evaluate the effect of aminocaproic acid (AMICAR), an inhibitor of fibrinolysis, on all hemorrhagic complications of ECMO including intracranial hemorrhage (ICH). In 1990, 49 neonates and 5 older children received ECMO therapy. None of these patients received AMICAR. In 1991, 51 neonates and 5 older children received ECMO. Forty-two of these patients who were considered to be at high risk for bleeding complications (preexisting or anticipated surgical procedures, preexisting ICH, or profound hypoxia, acidosis, coagulopathy, or prematurity) were given AMICAR. The remaining 14 low-risk neonates did not receive AMICAR, and for purposes of analysis were combined with the 1990 group. AMICAR was administered just prior to or after cannulation (100 mg/kg, intravenously) and was infused continuously at 30 mg/kg/h until decannulation. Except for the addition of AMICAR, the ECMO protocol was identical for these two patient groups. Patients who received AMICAR had significantly less bleeding while on ECMO (P = .03) and required fewer blood transfusions (P = .01) than patients not receiving AMICAR. This difference was most significant in the congenital diaphragmatic hernia and cardiac subgroups (P = .0001) and was not significant in the meconium aspiration subgroup (P = .1). The incidence of ICH in the neonatal subgroup was also significantly reduced with no patient on AMICAR developing a new or extending a preexisting ICH (P = .007). Reexploration of the cannulation site for bleeding was also reduced in the AMICAR-treated group but the difference failed to reach statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)

Intratracheal pulmonary ventilation and congenital diaphragmatic hernia: A report of two cases☆

Previous studies from our institution have shown that neonates with congenital diaphragmatic hernia (CDH), whose best postductal PaO2 (BPDPO2) was less than 100 mm Hg while on maximal conventional mechanical ventilation (CMV), had a mortality exceeding 90%. When combined with extracorporeal membrane oxygenation (ECMO), the mortality rose to 100% in those infants who developed hypercarbia following decannulation. Historically, those patients have required increasing ventilator support, leading to iatrogenic lung damage, and eventual death. Intratracheal pulmonary ventilation (ITPV) using the reverse thrust catheter (RTC) developed by Kolobow incorporates a continuous flow of humidified gas through a reverse Venturi catheter positioned at the distal end of the endotracheal tube. In animal studies, ITPV was shown to result in a reduced physiological dead-space (VD), to facilitate expiration, and to enhance CO2 elimination. In our current study, we have applied ITPV in two neonates with CDH who could not be weaned from ECMO because of uncontrollable hypercapnia, and who met above criteria for 100% mortality. In both cases, ITPV restored normal PaCO2 at low peak inspiratory pressure (PIP) with a substantial decrease in VD. We believe ITPV is suited to ventilating newborns with CDH in whom barotrauma is known to be common. Beyond its present use, ITPV may be useful to ventilate children with other forms of respiratory failure, and should be so considered along with other now available methods of mechanical pulmonary ventilation.

ECMO in evolution: the impact of changing patient demographics and alternative therapies on ECMO.

The incidence of neonatal extracorporeal membrane oxygenation (ECMO) is decreasing nationally. This decrease is presumed to be a result of the emergence of alternative technologies such as high-frequency oscillatory ventilation (HFOV), nitric oxide (NO), and surfactant therapy as well as others. The purposes of the present report were to determine just how rapidly the demographics of ECMO are changing and to determine the impact of competing technologies on ECMO use. The authors reviewed their entire ECMO experience of 455 cases (370 neonatal, 38 pediatric, and 47 cardiac). The neonatal cases also were separated into diagnostic groups: MAS (meconium aspiration syndrome), PPHN (persistent pulmonary hypertension of the newborn), RDS (respiratory distress syndrome), and sepsis. To allow statistical comparison, the patients were divided into four chronological groups, of equal 3-year duration, spanning the 12 years that ECMO has been available. The results of the analysis demonstrated four principle findings. (1) The total number of patients receiving ECMO per year was declining (P = .0001). This decline was attributable to a reduction in the total number of neonatal patients, with the exception of cases of congenital diaphragmatic hernia. (2) The complexity of each ECMO run was increasing, as evidenced by substantial increases in mean ECMO duration per patient and an increase in the incidence of patient complications on ECMO (P = .0001). (3) There has been a significant decrease in the overall survival rate for patients treated with ECMO (P = .0001). (4) The ECMO population mix has shifted away from straightforward neonatal cases and toward the more complex pediatric and cardiac cases. This demographic shift has occurred as a result of improvements in pre-ECMO management of neonatal patients, and is primarily responsible for the findings noted above. However, there also has been a worsening of condition severity within each diagnostic group, which also is partly responsible for the changes noted. If these trends continue, pediatric, cardiac, and CDH patients will likely account for the majority of ECMO patients. Consequently, existing ECMO centers must be prepared to adapt to the changing demographics by evolving programs that support pediatric, cardiac, and adult patients, in addition to neonates. Furthermore, the complexity associated with transporting these unstable older patients and the likelihood that the number of active ECMO centers will decline may require remaining ECMO centers to develop long-distance ECMO transport capabilities.

Coagulation factor deficiencies during initiation of extracorporeal membrane oxygenation.

OBJECTIVE We examined the hypothesis that critically ill patients receiving extracorporeal membrane oxygenation (ECMO) have reduced clotting factor levels, which may contribute to the risk of hemorrhagic complications. METHODS Blood samples were collected from 19 patients before and 1 hour after initiation of ECMO. Heparin present in samples was removed by ECTEOLA (epichlorohydrin triethanolamine) cellulose resin adsorption, and coagulation factors were assayed by automated techniques. Factor deficiency was defined as levels at least 2 SD less than published age-adjusted reference values. RESULTS Thirteen patients (68%) had deficiencies of two or more factors before ECMO. Despite inclusion of factor-containing blood products in the ECMO priming solution, 10 patients (53%) had deficiencies of two or more factors after initiation of ECMO. Four patients had intracranial hemorrhages and were found to be deficient in five or more factors at the time of cannulation. CONCLUSIONS Severe coagulation factor deficiencies are often present in patients requiring ECMO, and coagulation factors provided through the circuit prime are insufficient to ensure correction of these deficiencies. Deficiency of multiple coagulation factors may contribute to the risk of intracranial hemorrhage during ECMO; the practice of excluding factor-containing solutions from the circuit prime should be examined prospectively.

Respiratory deadspace measurements in neonates with congenital diaphragmatic hernia

OBJECTIVE To apply the technique of respiratory deadspace measurement to consecutive infants with congenital diaphragmatic hernia, who were referred to our institution, in order to assess the efficiency of gas exchange. DESIGN A cohort study evaluating the utility of deadspace measurements in neonates with congenital diaphragmatic hernia. SETTING Tertiary care pediatric intensive care unit in a university hospital. PATIENTS Thirty infants with congenital diaphragmatic hernia were studied on presentation to our institution, either before the institution of extracorporeal membrane oxygenation (ECMO) or after stabilization on ECMO. METHODS The CO2 concentration of expired gas sampled at the exhaust port of the test ventilator was continuously measured and transformed to mixed expired CO2 by the following formula that corrects for compressible volume measured by the ventilatory pneumotachometer: mixed expired CO2 = (PCO2 in exhaust gas) x (ventilatory pneumotachometer minute volume)/(minute volume at the proximal airway). We then utilized the Bohr-Enghoff method to calculate the deadspace/tidal volume ratio: deadspace/tidal volume ratio = (PaCO2 - mixed expired PCO2)/PaCO2. MEASUREMENTS AND MAIN RESULTS Deadspace/tidal volume ratio was calculated either before the institution of ECMO or during temporary separation from ECMO support as the patients demonstrated improvements in gas exchange and lung compliance. One hundred two measurements were made in 30 patients, with a mean of four measurements per patient (range 1 to 10). There was a significant (p = .005) difference between the first deadspace/tidal volume ratio measured, in survivors vs. nonsurvivors. The mean of the highest deadspace/tidal volume ratio in survivors was 0.47 compared with 0.62 in nonsurvivors (p = .003). A deadspace/tidal volume ratio of > or = 0.60 predicted mortality, with a positive predictive value of 80%, a negative predictive value of 79%, and an odds ratio of 15. The mean pre-ECMO deadspace/tidal volume ratio in those infants who ultimately required ECMO was significantly greater than the mean value for infants not requiring ECMO (0.65 vs. 0.43; p = .004). In patients who were treated with ECMO, survivors demonstrated a significant decrease in deadspace/tidal volume ratio during the course of ECMO. This decrease was not seen in the ECMO-treated patients who did not survive. CONCLUSIONS Predictors of outcome in infants with congenital diaphragmatic hernia have been complicated and contradictory, particularly in the ECMO era. We demonstrated that the respiratory deadspace can be easily quantified in these infants, and that a physiologic deadspace of > 0.60 is associated with a 15-fold increase in mortality rate. We also demonstrated that in those infants treated with ECMO, the survivors manifested a significant decrease in their deadspace/tidal volume ratio before ECMO decannulation.

Resection of a massive sacrococcygeal teratoma using hypothermic hypoperfusion: A novel use of extracorporeal membrane oxygenation☆

A 33-week-gestation infant with a massive sacrococcygeal teratoma weighted 4,000 g, but the actual weight of the infant was approximately 1,500 g. With the potential for massive blood loss and impaired lung compliance during resection, some type of cardiopulmonary support was necessary. Resection was undertaken with the assistance of venoarterial extracorporeal membrane oxygenation (ECMO) and hypothermic hypoperfusion. Immediately after removal of the tumor, which weighted 2,420 g, the infant was decannulated from ECMO, and the carotid artery was primarily reconstructed end-to-end. The amount of intraoperative blood loss was 550 mL Postoperatively, the child weighted 1,580 g. Follow-up head ultrasound results were normal, and the patient has done well. This is the first reported case in which ECMO with hypothermic hypoperfusion was used for resection of a massive tumor. This experience shows that ECMO is both useful and safe as a means of temporary cardiopulmonary support for resection of massive tumors in infants.