Delayed institution of extracorporeal membrane oxygenation is associated with increased mortality rate and prolonged hospital stay

Successful preoperative bridge with extracorporeal membrane oxygenation in three neonates with D-transposition of the great vessels and pulmonary hypertension

Pulmonary hypertension with transposition of the great arteries is associated with significant morbidity and mortality. At the worst end of the spectrum are patients who undergo extracorporeal support perioperatively. We describe our experience with three patients who received preoperative extracorporeal support and separated from cardiopulmonary bypass successfully on conventional postoperative care, with no significant deficits on follow-up.

Persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension of the newborn (PPHN) is characterized by elevated pulmonary vascular resistance resulting in right-to-left shunting of blood and hypoxemia. PPHN is often secondary to parenchymal lung disease (such as meconium aspiration syndrome, pneumonia or respiratory distress syndrome) or lung hypoplasia (with congenital diaphragmatic hernia or oligohydramnios) but can also be idiopathic. The diagnosis of PPHN is based on clinical evidence of labile hypoxemia often associated with differential cyanosis. The diagnosis is confirmed by the echocardiographic demonstration of - (a) right-to-left or bidirectional shunt at the ductus or foramen ovale and/or, (b) flattening or leftward deviation of the interventricular septum and/or, (c) tricuspid regurgitation, and finally (d) absence of structural heart disease. Management strategies include optimal oxygenation, avoiding respiratory and metabolic acidosis, blood pressure stabilization, sedation and pulmonary vasodilator therapy. Failure of these measures would lead to consideration of extracorporeal membrane oxygenation (ECMO); however decreased need for this rescue therapy has been documented with advances in medical management. While trends also note improved survival, long-term neurodevelopmental disabilities such as deafness and learning disabilities remain a concern in many infants with severe PPHN. Funded by: 1R01HD072929-0 (SL).

Adapted ECMO criteria for newborns with persistent pulmonary hypertension after inhaled nitric oxide and/or high-frequency oscillatory ventilation

PURPOSE

Early prediction of extracorporeal membrane oxygenation (ECMO) requirement in term newborns with persistent pulmonary hypertension (PPHN), partially responding to inhaled nitric oxide (iNO) and/or high-frequency oscillatory ventilation (HFOV), based on oxygenation parameters.

METHODS

This was a retrospective cohort study in 53 partial responders from among 133 term newborns with PPHN born between 2002 and 2007. Alveolar-to-arterial oxygen gradient (AaDO₂) values were determined in these 53 partial responders during the initial 72 h of iNO and/or HFOV treatment and compared between newborns who ultimately did (n = 11) and did not (n = 42) need ECMO.

RESULTS

Over 72 h, partial responders not requiring ECMO showed a more profound AaDO₂ decrease than those who needed ECMO (median decline 242.5 mmHg, IQR 144 to 353 mmHg, vs. 35 mmHg, IQR -15 to 123 mmHg; p = 0.0007). A decline of <123 mmHg over 72 h predicted the need for ECMO (sensitivity 82 %, specificity 79 %). At 72 h, AaDO₂ was significantly lower in partial responders without the need for ECMO than in those who did need ECMO (median 369 mmHg, IQR 258 to 478 mmHg, vs. 570 mmHg IQR 455 to 590 mmHg; p = 0.0008). An AaDO₂ >561 mmHg at 72 h predicted the need for ECMO (sensitivity 64 %, specificity 95 %, positive predictive value 78 %).

CONCLUSIONS

In term newborns with PPHN partially responding to iNO and/or HFOV, oxygenation-based prediction of the need for ECMO appears to be possible after 72 h. ECMO centers are encouraged to develop their own prediction model in order to prevent both lung damage and unnecessary ECMO runs.

Factors associated with survival in pediatric extracorporeal membrane oxygenation--a single-center experience

AIM

We aimed to examine outcomes of extracorporeal membrane oxygenation (ECMO) therapy in the pediatric population and identify pre-ECMO and on-ECMO characteristics that are associated with survival.

METHODS

We retrospectively reviewed the ECMO records at our institution between 1999 and 2008 and selected pediatric patients who were cannulated for respiratory failure or hemodynamic instability resistant to conventional interventions. We recorded details of pre-ECMO clinical characteristics, including blood gas variables and mechanical ventilatory support, and details of ECMO therapy including survival off ECMO and to hospital discharge. Predictors of survival were analyzed using logistic regression modeling and a prediction algorithm was developed.

RESULTS

Of the 445 ECMO runs, data from 58 consecutive patients were analyzed: 57% were successfully decannulated, and 48% survived to discharge from the hospital. The cohort included 32 (55%) female patients, 22 postoperative patients (38%), and 15 (26%) with an immunosuppressive condition, with a median age of 5 years and weight 19.5 kg, The mean duration of pre-ECMO respiratory support was 3 days, in the form of high-frequency oscillatory ventilation (n = 28, 48%) and conventional mechanical ventilation (n = 13, 22%). The median duration (interquartile range) of ECMO support was 142 hours (60, 321) or 5.9 days. Pre-ECMO pH above 7.2 (P < .001) and oxygenation index below 35 (P = .021) were associated with the highest survival rates. Pre-ECMO PaCO(2) and duration of mechanical ventilation were not associated with survival.

CONCLUSIONS

Based on our results, ECMO therapy should be considered early in children with oxygenation index greater than 35 with worsening metabolic status. The restriction of ECMO based on ventilator days alone needs to be revisited in this era of lung protective ventilation.

A 20-year experience on neonatal extracorporeal membrane oxygenation in a referral center

OBJECTIVE

Advances in treatment of neonatal respiratory failure are responsible for a decline in the number of newborns treated with extracorporeal membrane oxygenation (ECMO). The aim of this study are to determine demographic changes, focusing on time of referral, diagnosis, and respiratory parameters in neonates put on ECMO.

DESIGN

Retrospective review.

SETTING

Tertiary ECMO center.

PATIENTS

A total of 321 neonates were treated with ECMO from January 1987 to December 2006.

RESULTS

Overall number of patients increased with every 5-year period, whereby congenital diaphragmatic hernia (CDH) was the most common diagnosis (53%), followed by meconium aspiration syndrome (MAS) (21%), sepsis and/or pneumonia (13%), and others such as persistent pulmonary hypertension of the newborn (PPHN), respiratory distress syndrome (RDS), or hypoplasia of the lung (13%). Worsening severity of illness as measured by ECMO duration and days on ventilator has to be stated for all diagnoses. Nevertheless, survival rate remained stable; both overall and diagnosis-specific mortality rates did not change significantly. Of all children, 67% survived to discharge or transfer, while best rates were seen for MAS (94%), followed by sepsis and/or pneumonia (69%), CDH (62%), and other diagnoses (43%). Concerning survival rate, no difference between inborn and outborn children occurred. However, between early- and late-referred children, a referral to the ECMO center during the first 24 h of life was associated with a significantly higher rate of survival (77% versus 54%, p = 0.0004), predominantly seen for CDH (67% versus 35%, p = 0.02).

CONCLUSION

We strongly recommend timely transfer to an ECMO center in patients with CDH who are at risk of circulatory failure.

Extracorporeal Membrane Oxygenation for the Treatment of Neonatal Respiratory Failure

This review discusses the use of extracorporeal membrane oxygenation (ECMO) for the treatment of respiratory failure in neonates. After briefly reviewing the early history of neonatal ECMO, the authors describe the respiratory diagnoses most often treated with ECMO and the manner in which affected neonates are deemed to have “failed” conventional therapies and thus require ECMO. After reviewing the most common indications for ECMO, factors that influence the timing of conversion to extracorporeal life support, as well as criteria that may exclude patients from receiving ECMO therapy, are described. At the conclusion of this article, the authors discuss the long-term outcomes of neonates whose respiratory disease was treated with ECMO and the costs associated with that care.

ECMO for meconium aspiration syndrome: support for relaxed entry criteria

We compared the morbidity of patients with meconium aspiration syndrome (MAS) with that in patients with all other respiratory conditions treated with extracorporeal membrane oxygenation (ECMO) (no MAS). If ECMO for MAS was associated with a lower complication rate, then relaxed ECMO entry criteria could be considered. A retrospective review was performed of all patients in the national extracorporeal life support (ELSO) registry from 1989 to 2004. Complications were divided into mechanical, hematologic, neurologic, renal, pulmonary, cardiovascular, infectious, and metabolic categories. MAS and no-MAS patients were divided into veno-venous (VV) or veno-arterial (VA) ECMO categories, based on mode of ECMO used, and number of complications per patient in each category was determined. Statistical significance was determined by Chi-square test. A total of 1587 patients (700 MAS, 887 no MAS) on VV ECMO and 2723 (572 MAS, 2151 no MAS) on VA ECMO were identified with a total of 2415 complications in MAS and 9550 in no-MAS patients. Overall, MAS patients had a significantly lower number of complications per patient in each category versus no-MAS patients. These results indicate that regardless of type of ECMO, there are fewer complications on ECMO in MAS versus no-MAS patients. These data support the consideration of relaxed ECMO entry criteria for MAS.

Oxygenation index for extracorporeal membrane oxygenation: is there predictive significance?

Although extracorporeal membrane oxygenation (ECMO) is known to improve survival in neonates with respiratory failure, there has been a significant decrease in the use of ECMO in recent years. Alternative modalities such as high-frequency oscillatory ventilation (HFOV), inhaled nitric oxide (iNO), and surfactant therapy are associated with this decline. The criteria for the initiation of ECMO, developed about 20 years ago, are likely no longer relevant. We examined the predictive significance of the oxygenation index (OI) as a patient entry criterion for ECMO use. We sought a critical OI level predicting death or chronic lung disease (CLD) with and without ECMO use. We also examined whether patients with certain OIs are more likely to have worse outcomes. One hundred and seventy-four term-newborn admissions between 1995 and 2000 requiring mechanical ventilation were enrolled in the study. Receiver operating curve analysis was performed to find a cutoff value of OI for ECMO initiation. Mortality rates and CLD probability were compared to the worst OIs. Our 6-year ECMO administration experience showed that an OI of 33.2 is a suitable cutoff value for ECMO initiation with high sensitivity and specificity as a predictive criterion. The critical OI value associated with the CLD risk when ECMO is not used is in the 40s. OI is a good predictor of CLD; the probability of CLD increases with higher OIs. Our data support the trend toward the use of new interventions over ECMO, especially for patients with OI scores of less than 33.2. Only when the probability of ventilator-associated lung injury becomes significant is it better to consider ECMO than conventional modalities.

Neonatal ECMO: Current controversies and trends

Extracorporeal membrane oxygenation (ECMO), a technique for providing life support to patients with cardiac and/or respiratory dysfunction, allows the heart and lungs to "rest." The neonatal respiratory population has been a major benefactor of ECMO since 1982. Its use for neonatal respiratory disease increased dramatically until the past few years, when the number of neonatal respiratory ECMO cases began a downward trend. Fewer patients with persistent pulmonary hypertension of the newborn (PPHN), meconium aspiration syndrome, respiratory distress syndrome, or sepsis are requiring ECMO support as frequently as in the past. Many attribute this decline to the newer respiratory therapies-mainly, surfactant, high-frequency oscillatory ventilation, and inhaled nitric oxide. Neonates who continue to require ECMO today are sicker than the historic norm and have more complicated and lengthy ECMO runs. Patients with congenital diaphragmatic hernia, PPHN, and sepsis remain the most consistent in their representation among ECMO recipients within this author's institution, suggesting that the newer respiratory therapies have not had the same impact on these patients' needs for ECMO support. Better guidelines for determining which patients would benefit from earlier inititation of ECMO are needed.

Neonatal extracorporeal life support: impact of new therapies on survival

OBJECTIVE

To evaluate the effects of pre-extracorporeal life support (ECLS) management with nitric oxide (NO), high frequency ventilation (HFV), and surfactant on mortality among neonates supported with ECLS.

STUDY DESIGN

Extracorporeal Life Support Organization (ELSO) data on 7017 neonates cannulated for respiratory reasons between 1996 and 2003 were analyzed using chi2, analysis of variance, and logistic regression.

RESULTS

The use of ECLS declined by 26.6% over the study period with no significant change in mortality. Unadjusted ECLS mortality for NO-treated patients was lower than for infants not treated with NO (25.1% vs 28.6%, P = .0012) and for infants treated with surfactant than for infants not treated with surfactant (18.7% vs 30.3%, p <.0001.) Unadjusted mortality for HFV-treated patients was no different than for non-HFV-treated patients (26.0% vs 26.6%, P = .56). After adjusting for confounders (primary diagnosis, age at cannulation, ECMO year 1996-1999 vs 2000-2003), surfactant use was associated with decreased mortality. NO-treated neonates were less likely to have a pre-ECLS cardiopulmonary arrest than infants not treated with NO. NO, HFV, and surfactant were not associated with prolongation of ECLS or mechanical ventilation.

CONCLUSIONS

NO, HFV, and surfactant were not associated with increased mortality in neonates who require ECLS for hypoxic respiratory failure.

Developmental outcome in newborn infants treated for acute respiratory failure with extracorporeal membrane oxygenation: present experience

OBJECTIVE

To describe the later health status of newborn infants who received extracorporeal membrane oxygenation (ECMO) for acute respiratory failure in the era after the UK ECMO trial.

DESIGN

Prospective follow up study of newborn infants who received ECMO at a single centre between January 1997 and January 2001.

SETTING

Departments of ECMO and Paediatric Intensive Care, University Hospitals of Leicester.

PATIENTS

All babies who received ECMO within 14 days of birth.

INTERVENTIONS

Neurodevelopment screening using the schedule for growing skills-II (SGS-II) assessment tool.

MAIN OUTCOME MEASURES

Survival at 12 months of age by disease and functional development at follow up.

RESULTS

A total of 145 neonates received ECMO for treatment of respiratory failure. Of these, 108 (75%) were alive at 1 year of age. There were no deaths in children treated for respiratory failure secondary to meconium aspiration syndrome (73/145). Ninety three (86% of survivors) infants attended a follow up visit at 11-19 months postnatal age. Eighty two were classed as normal, seven as having "impairment", and four as having "severe disability".

CONCLUSIONS

Most newborn infants with acute respiratory failure treated with ECMO will have a normal neurodevelopment screening assessment at 11-19 months of postnatal age. There is no evidence to suggest that changes in neonatal practice since the UK ECMO trial have led to changes in outcome of infants undergoing ECMO therapy.

Extracorporeal membrane oxygenation in infants with meconium aspiration syndrome: a decade of experience with venovenous ECMO

BACKGROUND

Despite the emergence of new therapies for respiratory failure of the newborn with meconium aspiration syndrome (MAS), extracorporeal membrane oxygenation (ECMO) has a significant role as a rescue modality in these infants. Our objective was to compare the use of venovenous (VV) vs venoarterial (VA) ECMO in newborns with MAS who need ECMO and to ascertain the impact of new therapies in these infants during the last decade. We also evaluated how disease severity or time of ECMO initiation affected mortality and morbidity.

METHODS

A report of 12 years experience (1990-2002) of a single center, comparing VV and VA ECMO, is given. Venovenous ECMO was the preferred rescue modality for respiratory failure unresponsive to maximal medical therapy. Venoarterial ECMO was used only when the placement of a VV ECMO 14-F catheter was not possible; 128 patients met ECMO criteria, 114 were treated with VV ECMO, and 12 with VA ECMO. Two patients were converted from VV to VA ECMO.

RESULTS

Venovenous and VA ECMO patients had comparable birth weight (mean +/- SEM, 3.48 +/- 0.05 vs 3.35 +/- 0.15 kg) and gestational age (40.3 +/- 0.1 vs 40.7 +/- 0.3 weeks). Before ECMO, there was no difference between VV and VA ECMO patients in oxygenation index (60 +/- 3 vs 63 +/- 8), mean airway pressure (19.5 +/- 0.4 vs 20.8 +/- 1.5 cm H2O), alveolar-arterial O2 gradient (630 +/- 2 vs 632 +/- 4 torr), ECMO cannulation age (median [25th-75th percentiles], 23 [14-47] vs 26 [14-123] hours), or in the % of patients who needed vasopressors/inotropes (98% vs 100%). From November 1994, inhaled nitric oxide (NO) was available. Before VV ECMO, 67% of the patients received NO, 24% received surfactant, and 48% were treated with high-frequency ventilation (HFV). There was no significant difference between VV and VA ECMO patients in survival rate (94% vs 92%), ECMO duration (88 [64-116] vs 94 [55-130] hours), time of extubation (9 [7-11] vs 14 [9-15] days), age at discharge (23 [18-30] vs 27 [15-41] days), or incidence of short-term intracranial complications (5.3% vs 16.7%). For the total cohort of 126 infants, indices of disease severity (oxygenation index, alveolar-arterial O 2 gradient, mean airway pressure) did not correlate with outcome measures. Delay in ECMO initiation (> 96 hours) was associated with prolonged mechanical ventilation and hospitalization (P < .01). New therapies (NO, HFV, surfactant) in the second part of the decade were associated with a longer ECMO duration (98 [80-131] vs 87 [60-116] hours; P < .05), no delay in ECMO initiation time (23 [10-40] vs 24 [14-52] hours), and no significant change in survival (97% vs 92.5%). No patient was treated with VA ECMO after 1994.

CONCLUSIONS

Venovenous ECMO is as reliable as VA ECMO in newborns with MAS in severe respiratory failure who need ECMO. Delay in ECMO initiation may result in prolonged mechanical ventilation and increased length of hospital stay. The emergence of new conventional therapies (NO, HFV, surfactant) and particularly increased experience enable sole use of VV ECMO with no significant change in survival in infants with MAS.

The diseases treated with ECMO: focus on PPHN

Neonatal extracorporeal support is most often required for neonatal hypoxemic respiratory failure, usually accompanied by persistent pulmonary hypertension of the newborn (PPHN). PPHN is a clinical syndrome that results from the failure of pulmonary vascular transition to extrauterine life. Infants typically present shortly after birth with respiratory distress and cyanosis, but a structurally normal heart. The incidence of PPHN is estimated at 0.2% of live-born term infants. Respiratory failure and hypoxemia in the term newborn result from a heterogeneous group of disorders, and the therapeutic approach and response often depend on the underlying disease. PPHN can largely be thought of as one of three types: (1) the abnormally constricted pulmonary vasculature which is the most common type and includes diagnoses such as meconium aspiration syndrome, respiratory distress syndrome, and sepsis; (2) the structurally abnormal vasculature, which is often termed idiopathic PPHN; or (3) the hypoplastic vasculature such as is seen in congenital diaphragmatic hernia, or alveolar capillary dysplasia, a rare malformation of lung development. The pathophysiology of each type is dependent on the point in gestation when the normal transition to extrauterine life fails. This article will discuss the known pathophysiology in PPHN and new treatment modalities.

Meconium is a potent activator of complement in human serum and in piglets

Meconium aspiration syndrome (MAS) is a clinical condition in the newborn infant with a significant morbidity and mortality. The complex pathophysiology of MAS, leading to both pulmonary and systemic complications, is characterized by an incompletely understood inflammatory reaction. Treatment is symptomatic, mainly limited to airway cleaning and ventilatory support. In this study, we show for the first time that meconium is a potent activator of complement, a key mediator of inflammation. In vitro, meconium activated the alternative complement pathway in human umbilical cord serum as judged by a substantial increase in the alternative pathway convertase C3bBbP. The activation proceeded through C3 (C3bc) and the terminal C5-9 pathway (terminal SC5b-9 complement complex), whereas the classical and lectin pathways were not activated (C1rs-C1-inhibitor complexes and C4bc). The lipid fraction, containing, e.g. free fatty acids, and the water fraction, containing, e.g. bile acids, contributed equally to the complement activation. A blocking antibody to factor D (alternative pathway) completely inhibited the meconium-induced complement activation, whereas blocking antibodies to mannose-binding lectin (lectin pathway) and C2 (classical and lectin pathway) had no effect. In vivo, meconium induced systemic complement activation in a piglet model of MAS, paralleling the increase in lung dysfunction. In conclusion, meconium is a potent activator of the complement system both in vitro and in vivo. Complement may be important in the pathogenesis of MAS, and specific complement inhibition might be a possible treatment approach in MAS.

Expanded application of extracorporeal membrane oxygenation in a pediatric surgery practice

OBJECTIVE

To examine the breadth of application and resulting outcomes in a university-based extracorporeal membrane oxygenation (ECMO) program directed by pediatric surgeons.

SUMMARY BACKGROUND DATA

Several randomized control trials have supported the use of ECMO in neonates with respiratory failure. No comparable data exist for older children and young adults who may be afflicted with a variety of uncommon conditions. The indications for ECMO in these patients remain controversial.

METHODS

Patient data were recorded prospectively and reported to the Extracorporeal Life Support Organization. These data were analyzed by indications and outcomes on all patients treated since the inception of the program.

RESULTS

Two hundred sixteen patients were treated with 225 courses of ECMO. Neonates (188 [87%]) outnumbered 28 older patients (aged 6 weeks to 22 years). Overall, 174 patients survived (81%). Sixty-four of 65 (98.5%) neonates with meconium aspiration syndrome survived. ECMO support after heart (3), lung (2), heart-lung (1), and liver (1) transplant yielded a 57% survival to discharge. ECMO also resulted in survival of patients with uncommon conditions, including severe asthma (1), hydrocarbon aspiration (1/2), congestive heart failure due to a cerebral arteriovenous malformation (1), tracheal occlusion incurred during endoscopic stent manipulation (2), meningitis (1), and viral pneumonia (3/5).

CONCLUSIONS

ECMO can potentially eliminate mortality for meconium aspiration syndrome. Survival for other causes of respiratory failure in neonates and older children, while not as dramatic, still surpasses that anticipated with conventional therapy. Moreover, survival of transplant patients has been comparable to that achieved in other children.

Support of respiratory failure in the pediatric surgical patient

Severe respiratory failure in newborn and pediatric patients is associated with significant morbidity and mortality. Basic science laboratory investigation has led to advances in the understanding of ventilator-induced lung injury and in optimizing the supportive use of conventional ventilation strategies. Over the past few years, progress has been made in alternative therapies for supporting children and adults with severe respiratory failure. This review will focus on recent laboratory and clinical data regarding the techniques of lung protective ventilator strategies, inhaled nitric oxide, liquid ventilation, and extracorporeal life support (ECLS, ECMO). Some of these modalities are commonplace, while others may have much to offer the pediatric clinician if their benefit is clearly demonstrated in future clinical trials.