Comparison of six ECMO selection criteria and analysis of factors influencing their accuracy

Developing a new pediatric extracorporeal membrane oxygenation (ECMO) program

OBJECTIVES

We aimed to critically evaluate the effectiveness of a designated ECMO team in our ECMO selection process and patient outcomes in the first 3 years of our low-volume pediatric ECMO program.

METHODS

We conducted a retrospective chart review of patients who received an ECMO consultation between the start of our program in March 2015 and May 2018. We gathered clinical and demographic information on patients who did and did not receive ECMO, and described our selection process. We reflected on the processes used to initiate our program and our outcomes in the first 3 years.

RESULTS

69 patients received consultations, and of those, 50 patients were potential candidates. 19 (38%) of the candidates were ultimately placed on ECMO. There were statistically significant differences in oxygen saturation, paO₂, oxygenation index, A-aDO₂, lactate, and pH between the patients who went on ECMO and who did not. We improved our outcomes from 0% survival to discharge in 2015, to 60% in 2018, with an average of 63% survival to discharge over the first 3 years of our program.

CONCLUSIONS

In a low-volume pediatric ECMO center, having a designated team to assist in the patient selection process and management can help provide safe and efficient care to these patients, and improve patient outcomes. Having a strict management protocol and simulation sessions involving all members of the medical team yields comfort for the providers and optimal care for patients. This study describes our novel structure, processes, and outcomes, which we hope will be helpful to others seeking to develop a new pediatric ECMO program.

Extracorporeal Membrane Oxygenation with Veno-Venous Bypass and Apneic Oxygenation for Treatment of Severe Neonatal Respiratory Failure

Seven newborn infants with life-threatening respiratory failure were treated with veno-venous (V-V) extracorporeal lung support and apneic oxygenation after maximal ventilatory and pharmacological treatment failed. Diagnosis were meconium aspiration syndrome in 3 cases, respiratory distress syndrome in 2, sepsis in 1, congenital diaphragmatic hernia in 1. Before ECMO 6 infants received tolazoline, 4 surfactant, 3 high frequency ventilation, 1 prostaglandin E, 1 epoprostenol, 2 nitric oxide. Newborns were highly hypoxemic at admission and all but one underwent rescue cannulation. V-V bypass was performed with a single lumen single cannula and tidal flow was generated by an alternating clamp using a non-occlusive roller pump. The mean duration of bypass was 162, 4±162.3 hours and infants were extubated 94.5±74.8 hours after decannulation. Five newborns survived and two died. Growth and neurologic development of the older children is normal. The extracorporeal lung support with V-V bypass associated with apneic oxygenation was effective in reversing severe neonatal respiratory failure unresponsive to maximal ventilatory and pharmacological support. An early referral, prior to meeting ECMO criteria, is important in order to avoid hypoxic complications preceding ECMO.

Congenital diaphragmatic hernia

Congenital Diaphragmatic Hernia (CDH) is defined by the presence of an orifice in the diaphragm, more often left and posterolateral that permits the herniation of abdominal contents into the thorax. The lungs are hypoplastic and have abnormal vessels that cause respiratory insufficiency and persistent pulmonary hypertension with high mortality. About one third of cases have cardiovascular malformations and lesser proportions have skeletal, neural, genitourinary, gastrointestinal or other defects. CDH can be a component of Pallister-Killian, Fryns, Ghersoni-Baruch, WAGR, Denys-Drash, Brachman-De Lange, Donnai-Barrow or Wolf-Hirschhorn syndromes. Some chromosomal anomalies involve CDH as well. The incidence is < 5 in 10,000 live-births. The etiology is unknown although clinical, genetic and experimental evidence points to disturbances in the retinoid-signaling pathway during organogenesis. Antenatal diagnosis is often made and this allows prenatal management (open correction of the hernia in the past and reversible fetoscopic tracheal obstruction nowadays) that may be indicated in cases with severe lung hypoplasia and grim prognosis. Treatment after birth requires all the refinements of critical care including extracorporeal membrane oxygenation prior to surgical correction. The best hospital series report 80% survival but it remains around 50% in population-based studies. Chronic respiratory tract disease, neurodevelopmental problems, neurosensorial hearing loss and gastroesophageal reflux are common problems in survivors. Much more research on several aspects of this severe condition is warranted.

Fetal tracheal occlusion in lambs with congenital diaphragmatic hernia: role of exogenous surfactant at birth

Fetal tracheal occlusion (TO) has been used to reverse the lung hypoplasia associated with congenital diaphragmatic hernia (CDH). However, TO has a detrimental effect on type II pneumocyte function and surfactant production. Previously, we have shown that in surgically created CDH lambs, TO improved markedly the response to resuscitation even though the lungs remain surfactant deficient. The goal of this investigation was to assess the effects of exogenous surfactant administered at birth to CDH lambs with or without fetal TO during 8 h of resuscitation. Lambs were divided into five groups: CDH, CDH+surfactant (SURF), CDH+TO, CDH+TO+SURF, and nonoperated controls. A left-sided CDH was created in fetal lambs at 80 d gestation. TO was performed at 108 d, and the lambs were delivered by hysterotomy at 136 d. Bovine lipid extract surfactant was administered before the first breath and again at 4 h of life. All CDH+SURF lambs, but only three of five CDH lambs, survived up to 8 h. When compared with the corresponding nonsurfactant-treated group, surfactant-treated CDH and CDH+TO lambs did not demonstrate improved alveolar-arterial oxygen gradients, pH, or Pco(2). In fact, in the CDH+TO group, surfactant treatment significantly worsened ventilation efficiency as measured by the ventilation efficiency index. The observed improvement in pulmonary compliance secondary to surfactant treatment was not significant. This investigation demonstrates that prophylactic surfactant treatment at birth does not improve gas exchange or ventilation efficiency in CDH lambs with or without TO.

Neonatal surgical emergencies

Improvements in the diagnosis and treatment of congenital disorders have resulted in a change in surgical practice. Many conditions that formerly required corrective surgery immediately after birth are no longer surgical emergencies. Most babies with congenital anomalies that can be corrected by surgery are now stabilized and optimized before the procedure. This article focused on the more common conditions that require semi-elective or urgent surgery in the neonatal period. Salient features of each of these disorders were described. Factors unique to each of these conditions that can affect the anesthetic course of these children were discussed. Methods and techniques that may aid in the anesthetic management of these children were delineated.

[Congenital hernia of the diaphragm. A retrospective study of 123 cases recorded in the Neonatal Medicine Department, URHC in Lille between 1985 and 1996]

BACKGROUND

During the last ten years, new therapeutic strategies have been used in order to improve the management of congenital diaphragmatic hernia (CDH). CDH is associated with pulmonary hypoplasia, abnormal pulmonary vascular reactivity and pulmonary immaturity. Between 1985 and 1990, mechanical hyperventilation and early surgery were provided systematically. Since 1991, the management of CDH in our institution has involved a preoperative stabilization with exogenous surfactant replacement, gentle ventilation, high-frequency oscillation, nitric oxide or extracorporeal membrane oxygenation.

PURPOSE

To analyse the impact of the new therapeutic strategy on the survival and outcome of newborns with CDH.

METHODS

Retrospective review of all infants with CDH admitted to our institution from 1985 through 1996. Mortality and morbidity were compared between period I (1985-1990) and period II (1991-1996).

RESULTS

Between 1985 and 1996, 123 neonates were admitted to our Neonatal Department. Nine of them had another severe congenital malformation and were excluded from the study. Survival was 23% (12/52) in period I and 56% (35/62) in period II (p < 0.001). In period II, complications were more frequent among survivors in whom an extracorporeal membrane oxygenation was required (13 infants): bronchopulmonary dysplasia 77% (10/13), gastroesophageal reflux 61% (8/13), and hypotrophy 61% (8/13).

CONCLUSION

These data demonstrate a significant improvement in survival in CDH since the implementation of new therapeutic modalities. Nevertheless, a significant morbidity exists among the infants who survive a severe respiratory failure.

Prenatal diagnosis of congenital diaphragmatic hernia and pulmonary hypoplasia and therapeutic strategy

The outcome of fetuses with congenital diaphragmatic hernia (CDH) has been reported to be fatal when pulmonary hypoplasia (PH) is severe. As an indicator of PH, we attempted to measure the lung-thorax transverse area ratio (L/T) using ultrasonic echography. Immediate postnatal surgery was performed using high-frequency oscillatory ventilation (HFOV) and sometimes followed by extracorporeal membrane oxygenation (ECMO). Eighteen fetuses were treated and 14 survived. L/T correlated well with the best preductal arterial blood gas data before surgical reduction during manual ventilation and HFOV, while preductal PO2 and alveolar-arterial oxygen differences from patients managed with HFOV were better than those in patients with manual ventilation. Although L/T also correlated with the duration of O2 therapy and hospitalization in survivors without major anomalies, there was no significant difference between L/T in survivors and nonsurvivors. Because delayed institution of ECMO and complications related to ECMO management seemed to be a major cause of death in non-survivors, the unsalvageable L/T due to PH was estimated to be below 0.06 for HFOV and below 0.1 for conventional ventilation based on the correlation between L/T and preductal P02. These results suggest that L/T is a useful indicator of PH in patients with CDH and also that HFOV is advantageous in treating CDH with PH. The advantage of prenatal diagnosis in predicting unsalvageable L/Ts, should be considered in the therapeutic strategy.

Entry criteria for extracorporeal membrane oxygenation In neonates with congenital diaphragmatic hernia treated with high-frequency oscillatory ventilation

Although respiratory management with high-frequency oscillatory ventilation (HFOV) has generally been used for neonates with congenital diaphragmatic hernia (CDH), entry criteria for extracorporeal membrane oxygenation (ECMO) based on data from patients who underwent HFOV have not yet been reported. To establish entry criteria for ECMO in such patients, we retrospectively studied 36 neonates with CDH treated by HFOV in our institutions between 1986 and 1994. From the admission records, preductal and postductal arterial blood gas data and HFOV ventilation conditions for 72 h after admission were extracted. Oxygenation index (01) and alveolar-arterial oxygen gradient (A-aD02) time interval combinations were calculated. Patients were divided into two groups: candidates for ECMO (n = 22) who underwent ECMO (n = 18) or died without ECMO (n = 4); and non-candidates (n = 14), who survived without ECMO. Blood gas data in patients placed on ECMO were comparable to those in patients who died without ECMO: mean pre- and postductal OI for 4 h > 30, postductal A-aD02 ≥620 mmHg for 4 h, postductal A-aD02 ≥580 mmHg for 8 h, and postductal A-aD02 ?550 mmHg for 12 h showed better sensitivity with a specificity of more than 90% compared to entry criteria that had previously been used in our institutions: a postductal OI >40 for 4 h and postductal A-aDO2 ≥610 mmHg for 8 h. In addition, a combination of preand postductal OI >30 for 4 h indicated a sensitivity of 95.5% and a specificity of 92.9%.

The effect of on-site extracorporeal membrane oxygenation on the therapy choice and outcomes of neonates with persistent pulmonary hypertension

The effect of on-site extracorporeal membrane oxygenation (OS-ECMO) and selection criteria on the utilization rate of this technology is unknown. We retrospectively studied 55 neonates who were admitted to Arkansas Children's Hospital from 1985 to 1993. We compared the ECMO utilization, mortality, and morbidity rates for outborn neonates with moderate and severe persistent pulmonary hypertension (PPHN) before and after the establishment of an ECMO program with guidelines for its use at our institution. The rate of ECMO use was three times higher and the mortality rate was 13 times lower in the period after OS-ECMO compared with the period when ECMO was available only at other institutions. No differences were observed in the morbidity rates between the two periods. Physician decisions to initiate ECMO involved more than guidelines, since 37% of the increased ECMO use was not associated with use of the guidelines. Possible reasons for noncompliance with the guidelines are discussed. Neonates who had received medical therapy only and who had an oxygenation index > or = 30 and < 40 had no mortality. Our findings suggest that the need for ECMO in this group of neonates is low.

Predicting ventilation failure in children with inhalation injury

Despite advances in mechanical ventilatory support for patients with smoke inhalation injury, including the use of high-frequency flow-interruption ventilators such as the VDR, inhalation injury alone may increase mortality by as much as 20% in patients with thermal injury, and up to 60% when pneumonia occurs. Inhalation injury causes a primary large and small airway epithelial insult that results in ventilation abnormalities, rather than a primary alveolar lesion that results in oxygenation abnormalities as occur in multiple-system organ failure. Patients with inhalation injury requiring high ventilatory pressures experience complications of barotrauma and frequently succumb to necrotizing tracheobronchitis and oxygenation abnormalities after 2 to 4 weeks of mechanical ventilation. Ventilatory indexes obtained early in the postburn period allow the development of accurate predictive formulae that identify patients who will not be adequately supported by mechanical ventilation after smoke inhalation injury. Early identification of such patients will allow rapid conversion to other methods of ventilatory support that effect gas exchange, with minimal risk of further barotrauma, while inhalation injury healing occurs. Such predictors may be developed for other disease processes that are characterized by severe pulmonary ventilatory dysfunction.

Extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation has now evolved into standard therapy for patients unresponsive to conventional ventilatory and pharmacological support. This article presents a clinical review of extracorporeal life support and its application to neonatal and pediatric patients as well as children requiring circulatory support after open heart surgery.