Role of ECMO in the treatment of respiratory syncytial virus bronchiolitis: a collaborative report

Cost-effectiveness of palivizumab in infants with congenital heart disease: a Swedish perspective

Background

Infants with congenital heart disease (CHD) have an increased risk of morbidity and mortality during a respiratory syncytial virus (RSV) infection. The aim of this study was to estimate the cost-effectiveness of palivizumab as RSV-prophylaxis among infants with CHD, including the effect of delayed heart surgery and asthma.

Methods

A simulation model with data from the literature and health care authorities including costs and utilities was developed to estimate costs and health effects over a lifetime for a cohort of CHD infants receiving palivizumab compared to no RSV-prophylaxis.

Results

The prophylaxis treatment incurred a cost of 3664 EUR per treated infant. However, due to cost-savings from primarily avoiding hospitalizations (5145 EUR/treated infant) and avoiding heart complications due to delayed heart surgery (2082 EUR/treated infant), the RSV-prophylaxis treatment resulted in a total cost-saving of 3833 EUR per treated infant. At the same time, the prophylaxis-treated cohort accumulated more life-years and higher quality of life than the non-prophylaxis cohort.

Conclusion

This study confirms that RSV-prophylaxis in severe CHD infants less than one year of age is cost beneficial. Avoiding delayed heart surgeries is an important benefit of prophylaxis and should be taken into consideration.

The impact of the National Institute for Health Research Health Technology Assessment programme, 2003-13: a multimethod evaluation

BACKGROUND

The National Institute for Health Research (NIHR) Health Technology Assessment (HTA) programme supports research tailored to the needs of NHS decision-makers, patients and clinicians. This study reviewed the impact of the programme, from 2003 to 2013, on health, clinical practice, health policy, the economy and academia. It also considered how HTA could maintain and increase its impact.

METHODS

Interviews (n = 20): senior stakeholders from academia, policy-making organisations and the HTA programme. Bibliometric analysis: citation analysis of publications arising from HTA programme-funded research. Researchfish survey: electronic survey of all HTA grant holders. Payback case studies (n = 12): in-depth case studies of HTA programme-funded research.

RESULTS

We make the following observations about the impact, and routes to impact, of the HTA programme: it has had an impact on patients, primarily through changes in guidelines, but also directly (e.g. changing clinical practice); it has had an impact on UK health policy, through providing high-quality scientific evidence - its close relationships with the National Institute for Health and Care Excellence (NICE) and the National Screening Committee (NSC) contributed to the observed impact on health policy, although in some instances other organisations may better facilitate impact; HTA research is used outside the UK by other HTA organisations and systematic reviewers - the programme has an impact on HTA practice internationally as a leader in HTA research methods and the funding of HTA research; the work of the programme is of high academic quality - the Health Technology Assessment journal ensures that the vast majority of HTA programme-funded research is published in full, while the HTA programme still encourages publication in other peer-reviewed journals; academics agree that the programme has played an important role in building and retaining HTA research capacity in the UK; the HTA programme has played a role in increasing the focus on effectiveness and cost-effectiveness in medicine - it has also contributed to increasingly positive attitudes towards HTA research both within the research community and the NHS; and the HTA focuses resources on research that is of value to patients and the UK NHS, which would not otherwise be funded (e.g. where there is no commercial incentive to undertake research). The programme should consider the following to maintain and increase its impact: providing targeted support for dissemination, focusing resources when important results are unlikely to be implemented by other stakeholders, particularly when findings challenge vested interests; maintaining close relationships with NICE and the NSC, but also considering other potential users of HTA research; maintaining flexibility and good relationships with researchers, giving particular consideration to the Technology Assessment Report (TAR) programme and the potential for learning between TAR centres; maintaining the academic quality of the work and the focus on NHS need; considering funding research on the short-term costs of the implementation of new health technologies; improving the monitoring and evaluation of whether or not patient and public involvement influences research; improve the transparency of the priority-setting process; and continuing to monitor the impact and value of the programme to inform its future scientific and administrative development.

Viral Infection in the Development and Progression of Pediatric Acute Respiratory Distress Syndrome

Viral infections are an important cause of pediatric acute respiratory distress syndrome (ARDS). Numerous viruses, including respiratory syncytial virus (RSV) and influenza A (H1N1) virus, have been implicated in the progression of pneumonia to ARDS; yet the incidence of progression is unknown. Despite acute and chronic morbidity associated with respiratory viral infections, particularly in "at risk" populations, treatment options are limited. Thus, with few exceptions, care is symptomatic. In addition, mortality rates for viral-related ARDS have yet to be determined. This review outlines what is known about ARDS secondary to viral infections including the epidemiology, the pathophysiology, and diagnosis. In addition, emerging treatment options to prevent infection, and to decrease disease burden will be outlined. We focused on RSV and influenza A (H1N1) viral-induced ARDS, as these are the most common viruses leading to pediatric ARDS, and have specific prophylactic and definitive treatment options.

Bronchiolitis

Everyone on the planet is exposed to respiratory syncytial virus (RSV) infection by the age of 2 years. Most infants admitted to the pediatric intensive care unit (PICU) for respiratory support during this infection are previously healthy, but their principal risk for needing PICU treatment is young age. That is, if you are born in October/November in the northern hemisphere, then your first winter exposure to RSV is likely to be when you are less than 4 months of age and vulnerable because of poor respiratory mechanical reserve (Alonso et al. 2007). However, if you are born in May/June, then you will be 7–8 months during your first winter exposure to RSV, much bigger and stronger and have more efficient thoracic and diaphragmatic mechanics. In the PICU, the main predictors of severe outcome in previously well infants appear to be young age, presence of apnea, and pulmonary consolidation on admission chest radiograph (Tasker et al. 2000; Lopez Guinea et al. 2007). Taken together, we can say that more severe RSV bronchiolitis in PICU practice is typically a problem of pulmonary consolidation, poor respiratory mechanics, and poor reserve, in the younger infant.

Respiratory syncytial virus disease: prevention and treatment

Respiratory syncytial virus (RSV) is one of the most clinically important viruses infecting young children, the elderly, and the immunocompromised. Over the past decade, the most significant advance in the prevention of RSV disease has been the development of high-titered antibody products. Infection control is the only other strategy to prevent RSV disease. A humanized monoclonal antibody directed against the fusion (F) protein palivizumab, (Synagis®, MedImmune, Inc., Gaithersburg, MD), is given routinely on a monthly basis to premature infants and young children less than 24 months of age with underlying medical problems including prematurity, chronic lung disease, or cardiac disease to prevent RSV disease and hospitalization. Other products utilizing polyclonal or monoclonal antibodies or antibody fragments against the F protein have been developed and some already tested in patient populations. The only licensed antiviral treatment available today is ribavirin, a guanosine analogue generally administered as a small particle aerosol to immunocompromised patients with lower respiratory tract disease due to RSV. This drug has also been utilized in oral and intravenous forms, again mainly in immunocompromised patients. Promising new antiviral agents under development by multiple pharmaceutical and biotechnology companies include small molecule fusion inhibitors, attachment inhibitors, inhibitors of RNA synthesis, and small interfering RNA particles (siRNA).

Respiratory syncytial virus: diagnosis, treatment and prevention

Respiratory Syncytial Virus (RSV) is a common virus that infects children and adults; however, children younger than two years of age tend to develop more serious respiratory symptoms. RSV is responsible for thousands of outpatient visits (e.g., emergency room/primary care physician), hospitalizations and can result in death. Treatment is primarily supportive care and the illness resolves without complications in most children. RSV prophylaxis with palivizumab is an option for high-risk infants and children, which can decrease hospitalization and length of stay. Immunocompromised patients are a special population of which ribavirin and palivizumab may be used for treatment. Currently, no medication or vaccine available has been able to show a reduction in mortality from RSV. Future vaccines are in the developmental stage and will hopefully decrease the symptomatic and economic burden of this disease.

Inhaled prostacyclin and high-frequency oscillatory ventilation in a premature infant with respiratory syncytial virus-associated respiratory failure

In a 29-day-old premature infant with respiratory syncytial virus (RSV) pneumonia, we have shown an additive effect of high-frequency oscillatory ventilation (HFOV) and continuous inhalation of prostacyclin (iPGI(2)) with improvement of ventilation and oxygenation. The addition of continuous inhaled iPGI(2) to HFOV was beneficial in the treatment of hypoxemic respiratory failure owing to RSV-associated pneumonia. The improvement in alveolar recruitment by increasing lung expansion by HFOV along with less ventilation-perfusion mismatch by iPGI(2) appears to be responsible for the synergistic effect and favorable clinical outcome. We conclude that the combined therapy of HFOV and continuous inhaled iPGI(2) may be considered in RSV-associated hypoxemic respiratory failure in pediatric patients.

Assessment of Current Continuous Hemofiltration Systems and Development of a Novel Accurate Fluid Management System for Use in Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) with a renal replacement therapy such as continuous venovenous hemofiltration (CVVH) provides life-saving temporary heart and lung, and renal support in pediatric and neonatal intensive care units. However, studies have shown that this approach may be hampered due to the potentially inaccurate fluid delivery∕drainage of current intravenous (IV) fluid pumps, creating potential for excessive fluid removal and undesired degrees of dehydration. We present a simple and novel accurate fluid management system capable of working against the high volume flow and pressures typically seen in patients on ECMO. The accuracy of the in-line system implemented at Children’s Healthcare of Atlanta at Egleston was assessed experimentally. The data assisted in the development of a novel automated and accurate fluid management system that functions based on a conservation of volume approach to limit the inaccuracies observed in typical clinical implementations of CVVH. IV pump accuracy measurements demonstrated a standard error in net ultrafiltrate volume removed from the patient of up to 848.5±156ml over a period of 24h, supporting previous observations of patient’s dehydration during the course of a combined ECMO-CVVH treatment and justifying the need for a new fluid management system. The innovative design of the new device is expected to achieve either a perfect or controlled negative fluid balance between the ultrafiltrate and replacement fluid flow rates. Perfect fluid balance is achieved by imposing an identical displacement on two pistons, one delivering replacement fluid to the circuit and the other draining ultrafiltrate from the hemofilter. Fluid removal is managed via a second syringe-pump system that reduces the net replacement fluid flow rate with respect to the ultrafiltration flow rate. The novel fluid management system described in this paper is expected to provide an effective method to control precisely fluid flow rates in patients on ECMO. Therefore, this device could potentially improve the efficacy of ECMO therapy and constitute a safe and effective way of reducing fluid overload in patients with cardiorespiratory failure.

How does the changing profile of infants who are referred for extracorporeal membrane oxygenation affect their overall respiratory outcome?

OBJECTIVE

Extracorporeal membrane oxygenation has been shown to be effective in term neonates with severe but reversible lung disease within the context of randomized, controlled trials. Extracorporeal membrane oxygenation now has been open to a wider population of infants in the United Kingdom, and other treatments have become available. The population referred for extracorporeal membrane oxygenation, therefore, has changed. The aims of this study were to (1) compare respiratory outcomes of infants who received extracorporeal membrane oxygenation in recent years with those from 10 years ago and (2) determine whether respiratory outcome varied with diagnostic group.

METHODS

All infants who were referred to a single extracorporeal membrane oxygenation center and were <12 months old during a 7-year period were eligible. One year after extracorporeal membrane oxygenation, lung volume, airway conductance, maximum expiratory flow, and indices of tidal breathing were measured.

RESULTS

A total of 106 infants (77% of those eligible) were tested, and results were compared with those of 51 infants referred for extracorporeal membrane oxygenation as part of the original United Kingdom extracorporeal membrane oxygenation trial. Lung volume was not different, but there was a strong trend for the infants who were seen in more recent years to have better forced expiratory flow and specific airway conductance. Restricting analysis to the major subgroup (meconium aspiration) confirmed these findings. When divided into diagnostic subgroups, infants who required extracorporeal membrane oxygenation for respiratory distress syndrome or who were >2 weeks old when extracorporeal membrane oxygenation was commenced had a poorer respiratory outcome than others.

CONCLUSIONS

The respiratory outcome of infants who were treated beyond the tightly regulated criteria of the United Kingdom trial remains good and even shows a trend toward improvement. Certain subgroups require extracorporeal membrane oxygenation for longer and have poorer pulmonary function when followed up.

Prolonged ECMO support for virus-induced cardiorespiratory failure early after cardiac surgery

Extracorporeal membrane oxygenation (ECMO) after cardiac surgery is a rescue for life-threatening respiratory or circulatory failure. Although ECMO support for short periods (<10 days) represents an effective means of respiratory and cardiac support, treatment for longer periods remains controversial. We describe successful long-term use of ECMO support (48 days) for acquired virus-induced respiratory failure complicated by circulatory collapse following heart surgery.

Severe respiratory syncytial virus bronchiolitis in children: from short mechanical ventilation to extracorporeal membrane oxygenation

The objective of this study was to describe the characteristics of children who required mechanical ventilation (MV) or extracorporeal membrane oxygenation (ECMO) support for respiratory syncytial virus (RSV) bronchiolitis, and to identify risk factors associated with disease severity assessed by duration of MV, mortality and need for ECMO. Ventilated children under 1 year of age admitted for bronchiolitis were retrospectively studied over the 8-year period 1996-2003. The study population included 151 children. Of these, 38.4% were born prematurely and 8.6% had bronchopulmonary dysplasia (BPD). The mean age at initiation of MV was 61 days (+/-63 days). Infants were ventilated for a mean of 7.8 days (+/-7.5 days). Multivariate analysis revealed that prolonged duration of MV (>6 days, median value) was significantly associated with low gestational age ( P =0.02 for the group <32 weeks), requirement of neonatal oxygen supplementation ( P =0.03), BPD ( P =0.02) and positive tracheal aspiration culture ( P =0.004), in particular for Haemophilus influenzae ( P =0.03). Fourteen infants required ECMO with a mean period of MV before ECMO of 3.9 days (+/-4.5 days). Amongst these infants, the frequency of BPD was significantly higher as compared with the others ( P =0.001). Four infants died (survival rate 71.4%). The mean duration of ECMO for survivors was 12.1 days (+/-3.3 days).

CONCLUSION

The data suggest that gestational age, requirement of neonatal oxygen supplementation, bronchopulmonary dysplasia and tracheal colonisation with Haemophilus influenzae are correlated with prolonged mechanical ventilation in children with bronchiolitis. Only bronchopulmonary dysplasia was associated with a need for extracorporeal membrane oxygenation that may provide lifesaving support in infants refractory to conventional management.

Acute management of paediatric respiratory failure

Respiratory failure may be defined as failure of the lungs to maintain adequate gas exchange. It may occur as a result of alveolar hypoventilation, diffusion impairment, intrapulmonary shunting or ventilation–perfusion mismatch. Respiratory failure may be associated with hypoxaemia, hypercarbia or both. Hypoxaemia can cause tissue hypoxia and progressive hypercarbia can cause carbon dioxide narcosis. Both of these complications are potentially life threatening. Thus treatment of respiratory failure must aim both to maintain gas exchange and to treat the underlying cause.

Primary use of the venovenous approach for extracorporeal membrane oxygenation in pediatric acute respiratory failure

OBJECTIVES

To describe a single center's experience with the primary use of venovenous cannulation for supporting pediatric acute respiratory failure patients with extracorporeal membrane oxygenation (ECMO).

DESIGN

Retrospective chart review of all patients receiving extracorporeal life support at a single institution.

SETTING

Pediatric intensive care unit at a tertiary care children's hospital.

PATIENTS

Eighty-two patients between the ages of 2 wks and 18 yrs with severe acute respiratory failure.

INTERVENTIONS

ECMO for acute respiratory failure.

MEASUREMENTS AND MAIN RESULTS

From January 1991 until April 2002, 82 pediatric patients with acute respiratory failure were cannulated for ECMO support. Median duration of ventilation before ECMO was 5 days (range, 1-17 days). Sixty-eight of these patients (82%) initially were placed on venovenous ECMO. Fourteen patients were initiated and remained on venoarterial support, including six in whom venovenous cannulae could not be placed. One patient was converted from venovenous to venoarterial support due to inadequate oxygenation. Venoarterial patients had significantly greater alveolar-arterial oxygen gradients and lower PaO(2)/FIO(2) ratios than venovenous patients (p <.03). Fifty-five of 81 venovenous patients received additional drainage cannulae (46 of 55 with an internal jugular cephalad catheter). Thirty-five percent of venovenous patients and 36% of venoarterial patients required at least one vasopressor infusion at time of cannulation (p = nonsignificant); vasopressor dependence decreased over the course of ECMO in both groups. Median duration on venovenous ECMO for acute hypoxemic respiratory failure was 218 hrs (range, 24-921). Venovenous ECMO survivors remained cannulated for significantly shorter time than nonsurvivors did (median, 212 vs. 350 hrs; p =.04). Sixty-three of 82 ECMO (77%) patients survived to discharge-56 of 68 venovenous ECMO (81%) and nine of 14 venoarterial ECMO (64%).

CONCLUSIONS

Venovenous ECMO can effectively provide adequate oxygenation for pediatric patients with severe acute respiratory failure receiving ECMO support. Additional cannulae placed at the initiation of venovenous ECMO could be beneficial in achieving flow rates necessary for adequate oxygenation and lung rest.

Extracorporeal life support - state of the art

Extracorporeal life support (ECLS) has become an accepted therapeutic measure in the treatment of infants, children and adults with reversible respiratory or cardiac failure. The principle behind ECLS involves obtaining access to drain blood from the venous circulation into the extracorporeal circuit where it is oxygenated and cleansed of carbon dioxide before being returned to the circulation. The UK Collaborative ECMO Trial showed that an ECLS policy was clinically effective in terms of improved survival without a rise in severe disability at age 1 year. Long-term follow-up has confirmed these benefits. The value of ECLS in paediatric and, more recently, adult respiratory failure is becoming clearer. ECLS has a vital role to play in the support of paediatric cardiac surgery programmes. Recent advances include newer oxygenators, greater use of less invasive veno-venous support and the use of ECLS to support novel therapies used to treat severe congenital diaphragmatic hernia.

Ventilación mecánica en la bronquiolitis

Bronchiolitis is a prevalent viral disease in infants. Many of these infants require hospital admission and mechanical ventilation due to respiratory failure or apnea. The clinical and pathophysiological spectrum of this disease can range from two extremes, obstructive and restrictive disease, on which the indication for mechanical ventilation and the modality used should be based. Non-invasive ventilation is especially indicated in both obstructive and hypoxemic restrictive patterns and a pressure-controlled modality is recommended. In obstructive patterns, air trapping must be monitored, while in restrictive patterns the addition of positive end-expiratory pressure (PEEP) is indicated. High-frequency oscillatory ventilation is indicated in restrictive patterns with sever hypoxemia despite conventional ventilatory support or in cases of significant air leak syndromes. In all cases, a permissive hypercapnia strategy is recommended to prevent barotrauma. Sedation and muscle relaxation should be considered to facilitate adaptation to the ventilator and to try to limit the risks of air trapping, air leak, and barotrauma.

Extracorporeal membrane oxygenation for pneumonitis after a Glenn palliation

A five-month old male with a single ventricle palliated with a bidirectional cavopulmonary anastomosis developed severe respiratory insufficiency from respiratory syncytial virus (RSV) pneumonitis. He was successfully rescued with extracorporeal membrane oxygenation (ECMO) therapy and recovered with minimal morbidity.

New approaches to respiratory infections in children. Bronchiolitis and croup

Croup is a disease that is commonly seen in children younger than the age of 6 years. The cause is viral, with parainfluenza viruses and RSV being the two most common pathogens. Treatment consists primarily of supportive care, and parents usually have tried humidification and cool air exposure before the child presents to the ED. Children with moderate to severe croup are usually seen in the ED. The use of steroids in an oral preparation results in a clinical improvement of outpatients with mild to moderate croup and reduces the need for hospitalization. The dosage range for oral dexamethasone is 0.15 mg/kg to 0.6 mg/kg. Nebulized budesonide may also be used. Racemic or L-epinephrine, both of which are equally effective, can be used for symptomatic treatment in severe croup. After administration of racemic or L-epinephrine, hospitalization is not automatic and patients can be discharged safely from the ED after a 3-hour of observation period. There should be no respiratory distress, and the patient should have access to follow-up and emergency care if needed.

Mechanical ventilatory support in infants with respiratory syncytial virus infection

OBJECTIVE: To present a review of current knowledge of the use of mechanical ventilatory support in the management of infants with respiratory failure secondary to infection with respiratory syncytial virus (RSV). DATA SOURCES: MEDLINE and manual search for case reports and clinical trials that address management strategies for respiratory support of infants with RSV infection. Data Extraction and Synthesis: Critical appraisal of reported epidemiologic and clinical data regarding risk factors, pathophysiology, and efficacy of respiratory therapy. There is an increasing number of hospital admissions for RSV infection with a variable proportion of infants who need mechanical ventilatory support. The mortality rate is estimated to be <1% in infants without preexisting respiratory or cardiac disorders vs. <5% in those with preexisting respiratory or cardiac disorders. Optimal ventilator settings need to be refined according to the dominant obstructive or restrictive pattern with the aim to avoid barovolutrauma. The role of noninvasive ventilation and additional therapies (heliox, beta(2) agonists, surfactant) is not conclusively established. The indications for high-frequency oscillatory ventilation with the possible adjunction of inhaled nitric oxide deserve further study. Extracorporeal membrane oxygenation plays a minor role in severe cases that are refractory to conventional treatment. CONCLUSIONS: Conventional ventilation strategies are usually adequate for treating infants with severe RSV infection. Particular attention must be paid to the dominant pathophysiologic mechanism in a given condition. Prospective trials are needed to validate alternative therapeutic options and to improve the outcome of the rare but most severe cases that are difficult to control.

Recent advances in the management and prophylaxis of respiratory syncytial virus infection

Respiratory syncytial virus (RSV) infection is an important cause of morbidity, particularly in prematurely born infants who have had chronic lung disease. Current therapy is essentially supportive. Overall, the results of randomized trials do not support the use of bronchodilators, corticosteroids or Ribavirin. Nitric oxide and exogenous surfactant may improve the respiratory status of those infants who require ventilatory support. Nosocomial infection can be reduced by appropriate handwashing. There is no safe and effective vaccine for use in infants. Immunoprophylaxis reduces hospitalization and requirement for intensive care. Palivizumab, a humanized monoclonal antibody, is preferred to RSV immune globulin as the immunoprophylactic agent. Immunoprophylaxis should be reserved for infants at highest risk of severe respiratory syncytial virus infection, if this strategy is to be used most cost-effectively.

RSV: Management of the acute episode

Bronchiolitis is the most common lower respiratory tract infection in infants and is responsible for the majority of paediatric hospital admissions in the winter. Despite significant advances in pharmacotherapy, the management of infants with bronchiolitis has changed little over the years from supplemental oxygen and good fluid management. This paper reviews current treatment options for bronchiolitis, including the use of bronchodilators, adrenaline, steroids and ribavirin. More recent advances, including immunotherapy and intensive care, are discussed.

Venovenous versus venoarterial extracorporeal life support for pediatric respiratory failure: are there differences in survival and acute complications?

OBJECTIVES

To examine the Extracorporeal Life Support Organization (ELSO) registry database of infants and children with acute respiratory failure to compare outcome and complications of venovenous (VV) vs. venoarterial (VA) Extracorporeal Life Support (ECLS).

DESIGN

Retrospective cohort study.

SETTING

ELSO registry for pediatric pulmonary support.

PATIENTS

All nonneonatal pediatric pulmonary support ECLS cases treated at U.S. centers and reported to the ELSO registry as of July 1997. Patients were excluded if they had one or more of the following diagnoses: hematologic-oncologic, cardiac, abdominal surgical, burn, metabolic, airway, or immunodeficiency disorder.

INTERVENTIONS

Venoarterial or venovenous extracorporeal life support for severe pulmonary failure.

MEASUREMENTS AND MAIN RESULTS

From 1986 to June of 1997, 763 pediatric patients met the inclusion criteria. Overall, 595 were initially managed with VA bypass, and 168 with VV bypass. The VA group was younger (mean +/- SD, 26.1+/-42.2 months for VA vs. 63.5+/-68.7 months for VV) and smaller (11.8+/-15.1 kg vs. 22.9+/-23.8 kg) (p<.001). There were no differences between groups in number of days on mechanical ventilation before ECLS, number of hours on ECLS, or number of hours on mechanical ventilation post-ECLS in survivors. Mean pH and Paco2 values, positive end-expiratory pressure, and mean airway pressure just before placing the patient on ECLS were also similar. VA-treated patients had higher Fio2 requirements (p = .034), lower Pao2 (p = .047), and lower Pao2/Fio2 ratio (p = .014) just before cannulation. There was a trend of higher peak inspiratory pressure in VA-treated patients (p = .053). Overall, survival rate was not different for the two groups (55.8% for VA vs. 60.1% for VV; p = .33). Central nervous system complications were not different between the two groups. Examination of the same variables was then conducted after dividing the patients into four subgroups. There were no significant differences in survival or complications during bypass between VV and VA modes of ECLS in any subgroup. Stepwise logistic regression modeling was performed to control for variables associated with the outcome survival for VV and VA-treated groups, and variables measured before bypass were identified as being associated with improved survival. There was a trend of improved survival in the VV-treated patients (p = .12).

CONCLUSIONS

Overall survival of pediatric patients with acute respiratory failure supported by VA or VV ECLS was comparable. A randomized clinical trial may be useful in clarifying these observations.

Pulmonary failure after Norwood procedure: indication for extracorporeal membrane oxygenation? A case report

Today some authors consider univentricular repair a contraindication for postoperative cardiac extracorporeal membrane oxygenation (ECMO). The question is whether or not ECMO is indicated as pulmonary support in case of an overwhelming pulmonary infection during the postoperative course after a Norwood procedure. During the prolonged weaning period after a Norwood procedure using a 4 mm aortopulmonary shunt, proven respiratory syncytial virus (RSV) bronchiolitis occurred at the time of expected weaning from artificial ventilation. Venovenous ECMO was able to improve oxygenation, but when pulmonary opacification failed to resolve, ECMO was terminated after 12 days.

Acute respiratory distress syndrome caused by respiratory syncytial virus

Acute respiratory distress syndrome (ARDS) complicating severe respiratory syncytial virus (RSV) infection has been described in only a few infants. In contrast to the low mortality rates usually associated with RSV infections (< 5%), mortality rates in the range of 40-70% have been reported in pediatric patients with ARDS. However, studies on patients with ARDS are usually lumped with respect to causation, and the disease course of RSV-induced ARDS has not been previously studied. We examined the pulmonary function abnormalities of 37 infants with RSV-induced respiratory failure who were admitted to our pediatric intensive care unit for assisted ventilation. Measurements included respiratory mechanics, maximum expiratory flow-volume curves, and lung volumes. These allowed the calculation of a Murray lung injury score (modified for pediatric use) in which radiographic findings, ventilator settings, lung compliance, and blood gas results were considered. We identified ten infants with severe restrictive lung disease who fulfilled the clinical criteria for classification as ARDS. All had lung injury scores above 2.5, compatible with a diagnosis of ARDS. Twenty-seven infants had obstructive patterns of lung function consistent with a clinical diagnosis of RSV bronchiolitis. The patients with RSV-induced ARDS were significantly younger, and had a longer time on assisted ventilation (P < 0.05) and a higher proportion of predisposing illnesses (P < 0.05, odds ratio = 6.67, two-tailed Fisher's exact test) when compared with the patients who had obstructive disease. Only one patient (who had immunodeficiency) died, and all others were successfully managed on conventional mechanical ventilation. We conclude that RSV-induced respiratory failure represents a relatively benign cause of ARDS in pediatric patients. Our observations support the notion of differentiating ARDS with respect to causation, especially when novel and experimental therapy is considered and mortality rates are analyzed.

Extracorporeal membrane oxygenation as a bridge to definitive tracheal surgery in children

Extracorporeal membrane oxygenation was used as a bridge for three infants with complicated long segment congenital tracheal stenosis to tracheal homograft transplantation with cadaveric tracheal homograft and for one child, with an extensive traumatic tracheal laceration caused by aspiration of a sharp foreign body, to definitive tracheal repair. In all four cases mechanical ventilation was impossible and death almost certain without extracorporeal membrane oxygenation.