Use of extracorporeal membrane oxygenation in the treatment of respiratory syncytial virus bronchiolitis: the national experience, 1983 to 1988

Acute respiratory distress syndrome: A review of ARDS across the life course

Acute respiratory distress syndrome (ARDS) is a multifactorial, inflammatory lung disease with significant morbidity and mortality that predominantly requires supportive care in its management. Although initially described in adult patients, the diagnostic definitions for ARDS have evolved over time to accurately describe this disease process in pediatric and, more recently, neonatal patients. The management of ARDS in each age demographic has converged in the application of lung-protective ventilatory strategies to mitigate the primary disease process and prevent its exacerbation by limiting ventilator-induced lung injury. However, differences arise in the preferred ventilatory strategies or adjunctive pulmonary therapies used to mitigate each type of ARDS. In this review, we compare and contrast the epidemiology, common etiologies, pathophysiology, diagnostic criteria, and outcomes of ARDS across the lifespan. Additionally, we discuss in detail the different management strategies used for each subtype of ARDS and spotlight how these strategies were applied to mitigate poor outcomes during the COVID-19 pandemic. This review is geared toward both clinicians and clinician-scientists as it not only summarizes the latest information on disease pathogenesis and patient management in ARDS across the lifespan but also highlights knowledge gaps for further investigative efforts. We conclude by projecting how future studies can fill these gaps in research and what improvements may be envisioned in the management of NARDS and PARDS based on the current breadth of literature on adult ARDS treatment strategies.

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.

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.

Current treatment for acute viral bronchiolitis in infants

This paper provides an update and critical review of available data on the treatment of acute viral bronchiolitis in previously healthy infants, with special focus on new or promising therapies. The main potential benefits of medical assistance in these patients reside in the careful monitoring of their clinical status, the maintenance of adequate hydration and oxygenation, the preservation of the airway opened and cleared of secretions and the option to perform parental education. There is no convincing evidence that any other form of therapy will reliably provide beneficial effects in infants with bronchiolitis and currently, any treatment beyond supportive care should be prescribed on a case-by-case basis with watchful appraisal of its effects. Therapies such as ribavirin, IFN, vitamin A, antibiotics, mist therapy or anticholinergics, have not demonstrated any measurable clinical effect. Several studies and meta-analyses with beta(2)-agonists and corticosteroids have failed to show any benefit of significant extent, however, physicians keep favouring their use. Presently, adrenaline has received rather consistent support from clinical trials but it is not yet widely prescribed. There are other therapeutic strategies, for instance, heliox, hypertonic saline, noninvasive ventilation, physical therapy techniques, thickened feeds or palivizumab that have shown promising potential benefits, but evidence supporting its use is still limited and further studies should be warranted. In the meantime, infants with acute viral bronchiolitis should be treated following evidence-based clinical practice guidelines, keeping the patient central in the process and being sensitive to social, cultural and familiar influences on their treatment strategy.

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.

Extracorporeal life support in pediatric patients with heart failure

The prognosis of patients with end-stage heart failure presenting with acute clinical deterioration is poor. Extracorporeal membrane oxygenation (ECMO), however, can provide univentricular and biventricular cardiac support which has led to the extended application of ECMO to infants and children. With improving results, indications and modalities of mechanical support have changed, and mechanical bridge to cardiac transplantation will offer extended survival for selected patients. The purpose of this article is to provide comprehensive data of pediatric cardiac support and to discuss the central role of echocardiography in the estimation of cardiac performance during mechanical support. As a conclusion, one can predict that the encouraging results of today will lead to further technological developments, which will create individual technical solutions of different clinical applications.

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.

Extracorporeal membrane oxygenation for nonneonatal pulmonary and multiple-organ failure

PURPOSE

Extracorporeal membrane oxygenation (ECMO) is an accepted therapy for neonatal pulmonary failure, but its use in older children has been controversial.

METHODS

Over 13 years, 55 children (ages, 3 months to 16 years) were treated with venoarterial or venovenous ECMO. The diagnoses were viral, bacterial, or fungal pneumonia (24 patients); hydrocarbon or gastric aspiration (n = 10); adult respiratory distress syndrome (ARDS), sepsis, near drowning (n = 15); pulmonary contusion (n = 2); airway obstruction (n = 3); pulmonary artery foreign body (n = 1). Pre-ECMO blood gas ranges (and means) were PO2, 21 to 100 (n = 44); PCO2, 23 to 125 (n = 72); pH, 6.81 to 7.55 (n = 7.11).

RESULTS

All patients received inotropes, and 38 required dialysis or hemofiltration. ECMO was used for 20 to 613 hours (mean, 196 hours). Patient complications included cannulation site hemorrhage (n = 40), renal failure (n = 10), seizures (n = 8), stroke (n = 3), and cerebral hemorrhage (n = 2). Twenty-five patients (45%) survived ECMO, with 21 long-term survivors (10 pneumonia, five aspiration, five ARDS, one pulmonary contusion), five of whom have mild to moderate neurological deficit. Patients with combinations of pulmonary, cardiac, and renal failure, or sepsis did not survive.

CONCLUSIONS

ECMO is an invasive technique that can be life saving in the child with isolated respiratory failure, but its usefulness in children with multiorgan failure is less certain.

Respiratory syncytial virus pneumonia ventilated with high-frequency oscillatory ventilation

Four infants below 6 months of age with proven respiratory syncytial virus infection in need of assisted mechanical ventilation were successfully treated by high-frequency oscillatory ventilation. One of the four infants fulfilled the criteria for extracorporeal membrane oxygenation before the start of oscillation, and one on the second day on high-frequency oscillatory ventilation. However, extracorporeal membrane oxygenation was not needed in any of the infants. All survived, and three appeared to be without any pulmonary sequelae.

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 life support for the treatment of viral pneumonia: collective experience from the ELSO registry. Extracorporeal Life Support Organization

Viral pneumonia is the most common indication for pediatric extracorporeal life support (ECLS). Despite this fact, no previous studies have directly stratified patient outcome according to viral etiology.

METHODS

Using the Extracorporeal Life Support Organization (ELSO) registry database, the authors reviewed the national experience of patients undergoing ECLS with culture or serologically demonstrated viral pneumonia and compared outcome parameters according to viral etiology.

RESULTS

Patients differed with respect to age and weight according to the viral type. Patients with respiratory syncytial virus (RSV, median age 3 months), herpes simplex virus (HSV, 0.13 months), cytomegalovirus (CMV, 2.5 months), and adenovirus (0.6 months) were younger than those with other viruses (5.5 months). The patient groups did not significantly differ with respect to pre-ECLS Pao2 mean airway pressure (MAP), oxygenation index (OI), mode, or duration of ECLS. The overall survival of patients with viral pneumonia was 57%, although patients with RSV or CMV were found to have a 67% survival. Patients infected with HSV and adenovirus had a significantly lower survival rate (31% and 25%, respectively) when compared with those with RSV. In addition RSV pneumonia was associated with fewer cardiovascular complications than several of the other viral types. When comparison was made between survivors and nonsurvivors, a higher last pre-ECLS MAP and increased incidence of elevated creatinine and renal failure requiring dialysis were noted among nonsurvivors.

CONCLUSION

ECLS remains an important modality in the treatment of neonatal and pediatric patients with respiratory failure secondary to viral pneumonia. The survival rate of these patients varies according to the type of viral infection.

The impact of extracorporeal membrane oxygenation on survival in pediatric patients with acute respiratory failure. Pediatric Critical Care Study Group

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) has been used with increasing frequency in the treatment of acute respiratory failure in pediatric patients. Our objective in this study was to test the hypothesis that ECMO improves outcome in pediatric patients with acute respiratory failure.

DESIGN

Multicenter, retrospective cohort analysis.

SETTING

Forty one pediatric intensive care units participated in the study under the auspices of the Pediatric Critical Care Study Group.

PATIENTS

All pediatric patients admitted to the participating institutions with acute respiratory failure during 1991 were included. Patients with congenital heart disease, contraindications to ECMO, or incomplete data were excluded, yielding a data set of 331 patients from 32 hospitals.

INTERVENTIONS

Conventional mechanical ventilation, high-frequency ventilation, and extracorporeal membrane oxygenation.

MEASUREMENTS AND MAIN RESULTS

Multivariate logistic regression analysis was used to identify factors associated with survival. In a second analysis, pairs of ECMO and non-ECMO patients, matched by severity of disease and respiratory diagnosis, were compared. The use of ECMO (p = .0082), but not the use of high-frequency ventilation, was associated with a reduction in mortality. Other factors independently associated with mortality included oxygenation index (p < .0001), Pediatric Risk of Mortality score (PRISM) (p < .0001) and the Paco2 (p = .045). In 53 diagnosis- and risk-matched pairs, there was a significantly lower mortality rate (26.4% vs. 47.2%; p < .01) in the ECMO-treated patients. When all patients were stratified into mortality risk quartiles on the basis of oxygenation index and PRISM score, the proportion of deaths among ECMO-treated patients in the 50% to 75% mortality risk quartile was less than half the proportion in the non-ECMO treated patients (28.6% vs. 71.4% p < .05)> No effect was seen in the other quartiles.

CONCLUSIONS

The use of ECMO was associated with an improved survival in pediatric patients with respiratory failure. The lack of association of outcome with treatment in the ECMO-capable hospital or with another tertiary technology (i.e. high-frequency ventilation) suggests that ECMO itself was responsible for the improved outcome. Further studies of this procedure are warranted but require broad-based multi-institutional participation to provide sufficient statistical power and sensitivity to demonstrate efficacy.

Probability of survival after prolonged extracorporeal membrane oxygenation in pediatric patients with acute respiratory failure. Extracorporeal Life Support Organization

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) has been used with increasing frequency for respiratory failure that is unresponsive to conventional therapy. We examined the relationship between duration of ECMO and outcome to understand whether prolonged ECMO (duration of the procedure for > 14 days) was more commonly associated with futile therapy or eventual recovery.

DESIGN

A cohort study of all patients reported to the Pediatric ECMO Registry for Acute Respiratory Failure of the Extracorporeal Life Support Organization.

SETTING

Tertiary hospitals (n = 83) capable of providing extracorporeal support for pediatric patients.

PATIENTS

Children (n = 382) between the ages of 1 wk and 18 yrs of age with severe respiratory failure.

INTERVENTIONS

Extracorporeal membrane oxygenation.

MEASUREMENTS AND MAIN RESULTS

The death or live hospital discharge of ECMO-treated patients, together with the post-ECMO mechanical ventilation course, were examined as a function of duration of ECMO and of pre-ECMO respiratory status. The occurrence of complications and the causes of death were also noted. The criteria used to initiate ECMO, as well as the determination of the futility of further ECMO, were determined by local practice at individual centers. There were 382 patients treated with ECMO, of whom 184 (48%) survived. The proportional survival in the patients treated for the longest duration was similar to the overall group. The cause of death was given for 168 patients: 32 neurologic deaths; nine deaths due to ECMO complications; and 30 deaths due to nonpulmonary organ failure. There were 97 deaths due to elective ECMO termination; 80 of these deaths occurred after the determination of the futility of anticipating pulmonary recovery. The latter deaths occurred at widely varying durations of ECMO, with a median of 282 hrs. However, at that same duration, 47 eventual survivors (26% of all survivors) continued to receive ECMO. By discriminant analysis, the survival rate was independently related (r2 = .18; p < .0001) to peak ventilator inspiratory pressure before ECMO and duration of intubation before ECMO, patient age, and the occurrence of several complications.

CONCLUSIONS

While the survival rate in pediatric patients receiving ECMO appears related to the severity of lung disease and to the occurrence of ECMO complications, the survival rate in patients treated with ECMO courses of > 2 wks was similar to the survival rate of patients treated for shorter periods of time. ECMO was terminated in some patients for pulmonary futility at durations of ECMO associated with survival in substantial numbers of patients in whom ECMO was continued.

Sonographically guided cannula positioning for extracorporeal membrane oxygenation

Drainage problems due to catheter malpositioning are acutely life-threatening in patients undergoing extracorporeal membrane oxygenation. In order to reduce these complications we introduced sonographically guided catheter positioning. We compare the outcome in a group of patients with blind cannula positioning to that in a group with sonographically guided catheter positioning. Our results show that neonates and young infants especially are at high risk of drainage problems due to catheter malposition and that their outcome could be markedly improved by introducing sonographically guided cannula insertion.

Treatment of respiratory failure in an infant with bronchopulmonary dysplasia infected with respiratory syncytial virus using inhaled nitric oxide and high frequency ventilation

A 2-month-old, former 28-week premature infant with bronchopulmonary dysplasia infected with respiratory syncytial virus was treated with nitric oxide and high frequency oscillatory ventilation after conventional therapy failed. Nitric oxide and high frequency oscillatory ventilation rapidly improved oxygenation allowing recovery without the need for extracorporeal membrane oxygenation. This treatment regimen should be considered as an option in high-risk infants with respiratory syncytial virus infection who meet extracorporeal membrane oxygenation criteria.

Emergency and long-term extracorporeal life support following acute myocardial infarction: rescue from severe cardiogenic shock related to stunned myocardium

There has been no report regarding therapy of extracorporeal life support (ECLS) that showed stunned myocardium echocardiographically and electrocardiographically in patients with acute myocardial infarction. ECLS was performed in eight patients with cardiogenic shock or arrest unresponsive to catecholamines and intra-aortic balloon pumping following myocardial infarction; these patients required prolonged external cardiac massage. After the initiation of ECLS, both blood pressure and metabolic acidosis improved in all patients. Four of eight patients were weaned from ECLS after a mean of 69.3 h, which was far longer than previously reported in patients with ischemic heart disease. Three of these patients survived, and cardiac function recovered to NYHA class II in two of the survivors and class III in the other. The other five patients did not recover from coma during ECLS and died. A marked improvement of ventricular wall motion was seen in two survivors with the disappearance of pathologic Q waves after the initiation of ECLS. No occlusion of the coronary arteries or bypass grafts was observed in any of the survivors. These findings suggested the existence of stunned myocardium with myocardial reperfusion. The recovery of stunned myocardium may be delayed for days or even weeks, hence the extended period of ECLS therapy was theoretically justifiable. We conclude that long-term ECLS is a useful therapeutic method for patients with severe cardiogenic shock that is related to stunned myocardium.

Mercury inhalation poisoning and acute lung injury in a child. Use of high-frequency oscillatory ventilation

Acute mercury inhalation poisoning is a rare cause of acute lung injury. It is commonly fatal in the young child because of progressive pulmonary failure. We describe a 3-month-old infant who survived this insult with the use of high-frequency oscillatory ventilation. This form of support may be an option in the patient with severe adult respiratory distress syndrome (ARDS) or air leak syndromes.

Inhaled nitric oxide for a severe respiratory syncytial virus infection in an infant with bronchopulmonary dysplasia

OBJECTIVE

To report the first case of ARDS in children treated with nitric oxide (NO) inhalation.

METHODS

A 13-months infant presented with BPD and severe hypoxemia related to RSV infection and ARDS. Inhaled NO was delivered in the ventilatory circuit of a continuous flow ventilator (Babylog 8000, Dräger) in a concentration of 20-80 ppm for 7 days. NO and NO2 were continuously monitored (Polyton Draeger). Respiratory mechanics were evaluated by using the method of passive inflation by the ventilator.

RESULTS

NO inhalation improved oxygenation (tcSaO2) and reduced respiratory system resistance without affecting arterial pressure. NO2 level remained below 5 ppm, and methaemoglobin level below 1%. The child survived without neurologic sequela.

CONCLUSIONS

Two mechanisms to explain oxygenation improvement can be suggested: selective improvement in perfusion of ventilated regions and bronchodilation.

Extracorporeal membrane oxygenation: support for overwhelming pulmonary failure in the pediatric population. Collective experience from the extracorporeal life support organization

Data from the Extracorporeal Life Support Organization (ELSO) regarding the use of extracorporeal membrane oxygenation (ECMO) in pediatric patients with respiratory failure are reviewed. Two hundred eighty-five children between the ages of 14 days and 18 years were supported with ECMO between January 1982 and September 1991. Although these data represent the experience of 52 ECMO centers, seven centers accounted for over 50% of the total. The patients had a mean age of 33 +/- 48 months with a median age of 13 months: 137 (48%) were male and 148 (52%) were female. There were numerous primary pulmonary diagnoses: the two most common were presumed viral pneumonia (32%) and adult respiratory distress syndrome (28%). Entry criteria for ECMO, although poorly defined and specific to each institution, attempted to identify children with an 85% to 100% predicted mortality. The survival rate with ECMO was 47% (135/285). Pre-ECMO mechanical ventilatory support was extreme with an FIO2 .97 +/- .07 and a mean airway pressure (MAP) 23.6 +/- 8 cm H2O used to achieve PaO2 of 50 +/- 39 and PaCO2 51 +/- 22 mm Hg. The MAP was significantly higher in nonsurvivors versus survivors (25.3 +/- 8.7 v 22.0 +/- 7.1 cm H2O, P < .01). The duration of ECMO was 4 hours to 35.5 days with a mean of 245 +/- 165 hours, which is approximately 10 days. Duration for survivors was 222 +/- 151 hours compared with 266 +/- 176 hours for nonsurvivors. ECMO complications are divided into two categories: mechanical (directly related to the ECMO circuit) and medical (patient related).(ABSTRACT TRUNCATED AT 250 WORDS)

Extracorporeal life support for patients undergoing prolonged external cardiac massage

From November 1987 to February 1992, extracorporeal life support (ECLS) was used for four patients undergoing prolonged external cardiac massage following cardiac arrest. Their underlying diseases consisted of acute pulmonary embolism, pulmonary arterial thrombosis due to protein C deficiency, acute inferior left ventricular infarction accompanied by right ventricular infarction and thoracic contusion. After the initiation of ECLS, hemodynamic variables and metabolic acidosis improved in all of the cases. The case of pulmonary embolism and the case of acute myocardial infarction were successfully weaned from ECLS without complications. They were later discharged ambulatory from the hospital. The patient with pulmonary arterial thrombosis, who was comatose, became alert after the initiation of ECLS. However the patient finally died due to diffuse and massive pulmonary arterial thrombosis, which was probably related to protein C deficiency. The patient with thoracic contusion was also comatose before ECLS. He did not recover from the coma and died soon after the disconnection of ECLS. The latter two cases were suspected to have had irreversible organ failures not responsive to mechanical support of both circulation and respiration. We conclude that ECLS is a very useful method for patients requiring prolonged cardiac massage following cardiac arrest.

Current perspectives on respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is the most important cause of acute viral bronchiolitis and pneumonia in infants and children. Management of RSV infection has changed dramatically over the past 5 to 7 years because of (1) the advent of widely available rapid tests for its specific identification and (2) use of the antiviral agent ribavirin (Virazole). Although RSV infection remains a life-threatening disease, particularly in certain high-risk groups, appropriate management and judicious use of ribavirin should help physicians reduce its morbidity and mortality.

Prolonged extracorporeal support for nonneonatal respiratory failure

Extracorporeal membrane oxygenation (ECMO) is effective for newborns with pulmonary failure unresponsive to conventional therapy. However, ECMO for the older child and adult has been controversial and not widely utilized. Over 4 years, 24 patients (aged 4 months to 16 years; 11 boys, 13 girls) underwent venoarterial ECMO (duration, 7 to 19 days) for respiratory failure. The diagnoses were: viral pneumonia (7), hydrocarbon aspiration (6), sepsis with adult respiratory distress syndrome (ARDS) (2), bacterial pneumonitis (2), tracheal stenosis (1), bilateral pulmonary contusion (1), diaphragmatic hernia with ARDS (1), ketoacidosis with ARDS (1), pulmonary artery injection of hydrocarbon (1), drowning (1), and epiglottis with barotrauma (1). Pre-ECMO blood gas ranges (and means) were PO2 18 to 65 (46), and PCO2 47 to 112 (65). Nineteen patients received dopamine, dobutamine, or other inotrope for associated cardiac and/or renal failure. Cannulation for ECMO was through neck or groin vessels in 17, and sternotomy in 7. ECMO flow rates were 150 to 250 mL/kg/min, to maintain PO2 greater than 100 and PCO2 less than 40. Nine patients (41%) survived ECMO, with eight long-term survivors, (4 hydrocarbon aspiration or injection, 1 pulmonary contusion, 1 viral pneumonia, 1 ARDS, 1 barotrauma), three of whom have mild neurological deficit. All patients with sternotomy, and 8 of 15 with neck and/or groin cannulation, required 1 to 5 explorations for hemorrhage while on ECMO. All survivors had primarily pulmonary failure; patients with combinations of pulmonary, cardiac, and renal failure did not survive. ECMO can be life-saving in the child with isolated pulmonary failure, but its efficacy in patients with multiorgan failure is uncertain.