A decade of experience with neonatal extracorporeal membrane oxygenation

Meconium aspiration syndrome: from pathophysiology to treatment

Meconium aspiration syndrome (MAS) is a clinical condition characterized by respiratory distress in neonates born through meconium-stained amniotic fluid (MSAF). Despite advances in obstetric practices and perinatal care, MAS remains an important cause of morbidity and mortality in term and post-term newborns. Since the 1960s, there have been significant changes in the perinatal and postnatal management of infants born through MSAF. Routine endotracheal suctioning is no longer recommended in both vigorous and non-vigorous neonates with MSAF. Supportive care along with new treatments such as surfactant, inhaled nitric oxide, and high-frequency ventilation has significantly improved the outcome of MAS patients. However, determining the most appropriate approach for this condition continues to be a topic of debate. This review offers an updated overview of the epidemiology, etiopathogenesis, diagnosis, management, and prognosis of infants with MAS.

Neonatal respiratory extracorporeal membrane oxygenation and primary diagnosis: trends between two decades

OBJECTIVE

Examine changing neonatal respiratory extracorporeal membrane oxygenation (ECMO) practice trends and outcomes.

STUDY DESIGN

Retrospective cohort study comparing neonatal respiratory ECMO in the 1990 and 2010 decades (1994-1995 and 2014-2015). Patients ≤ 30 days of life, reported to the Extracorporeal Life Support Organization registry, were included.

RESULTS

Four thousand one hundred and twenty-five patients met inclusion criteria. ECMO cases decreased by 33%. The primary ECMO diagnosis changed significantly over time (p < 0.0001). Survival to discharge decreased (76 vs 67%, p < 0.0001) and ECMO duration increased (131 vs 158 h, p < 0.001). Lung recovery was the most common reason to discontinue ECMO although family request for withdrawal and a diagnosis considered "incompatible with life" was increasingly common in the 2010s.

CONCLUSION

Although the use of ECMO for neonatal respiratory diagnoses has decreased over time, its use has increased for patients with more complex diagnoses and ECMO duration is longer. ECMO continues to be an important supportive therapy, improved understanding of which patients would benefit most is needed.

High-Frequency Oscillatory Ventilation and Nitric Oxide: Alternative or Complementary to ECMO

One hundred and seventy-seven term or near-term neonates were referred to an ECMO center for severe PPHN-associated diseases. In 2 time periods from 1987 to 1991 and from 1992 to April 1995 alternative treatment modes were tried in an attempt to obviate ECMO. During the first time period patients underwent trial high-frequency oscillatory ventilation before ECMO. In the second time period patients first received inhaled NO followed by HFOV in a non-responders. If this also failed HFOV was combined with I NO. In both time periods about 40% of the patients were spared ECMO treatment by these alternative treatment modalities. I NO only benefited 15% of the ECMO candidates who apparently had fared just as well on HFOV alone in the preceding time period. While patients who were improved by I NO were spared HFOV with its potential severe complications, i.e. air leaks and cardiocirculatory instability, more extended long-term studies will have to show which of these 2 treatment modalities (INO or HFOV) should be given first priority in an attempt to avoid ECMO in neonates with severe respiratory failure.

The Influence of Lung Injury due to Mechanical Ventilation on the Initiation of Ecmo

Before the entry criteria for extracorporeal membrane oxygenation (ECMO) are met, newborns may require aggressive mechanical ventilation which may result in lung injury. The question arises whether the presence of a pneumothorax in these infants plays a role in the prognosis. Of the 21 newborns transferred to our hospital for ECMO, 8 were treated with ECMO. 9 of the 21 newborns developed a pneumothorax with conventional ventilation and 6 of these 9 newborns subsequently required ECMO. Infants who developed a pneumothorax but did not meet ECMO criteria and remained in the oxygenation index (01) range between 25 and 40 for more than 2 days had a poorer prognosis. If adequate oxygenation cannot be attained with acceptable mechanical ventilation and a more aggressive ventilation results in a pneumothorax, ECMO should be considered even if the oxygenation index is below 40.

Pediatric Extracorporeal Membrane Oxygenation: An Introduction for Emergency Medicine Physicians

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) therapy has supported critically ill pediatric patients in the intensive care unit setting with cardiac and respiratory failure. This therapy is beginning to transition to the emergency department setting.

OBJECTIVE OF REVIEW

This article describes the fundamentals of ECMO and familiarizes the emergency medicine physician with its use in critically ill pediatric patients.

DISCUSSION

ECMO can be utilized as either venoarterial (VA) or venovenous (VV), to support oxygenation and perfusion in respiratory failure, sepsis, cardiac arrest, and environmental hypothermia.

[Current state of neonatal extracorporeal membrane oxygenation in Colombia: description of the first cases]

Extracorporeal membrane oxygenation is considered a rescue therapy and complex vital support with benefits in cardiorespiratory diseases during neonatal period that fulfil the characteristics of being reversible in neonates older than 34 weeks. The criteria for patient selection and its prompt use are critical for the final result. Even though new alternatives for management of hypoxemic respiratory failure in full term and almost full term neonates have decreased its use, congenital diaphragmatic hernia continues being a complex disease where it can have some applicability. Even though our experience is beginning, constant training will make of extracorporeal membrane oxygenation an option for complex patients in whom maximum therapy fails. This is a report of the first neonatal cases of hypoxemic respiratory failure managed at Fundación Cardiovascular de Colombia.

Advances in the management of meconium aspiration syndrome

Meconium aspiration syndrome (MAS) is a common cause of severe respiratory distress in term infants, with an associated highly variable morbidity and mortality. MAS results from aspiration of meconium during intrauterine gasping or during the first few breaths. The pathophysiology of MAS is multifactorial and includes acute airway obstruction, surfactant dysfunction or inactivation, chemical pneumonitis with release of vasoconstrictive and inflammatory mediators, and persistent pulmonary hypertension of newborn (PPHN). This disorder can be life threatening, often complicated by respiratory failure, pulmonary air leaks, and PPHN. Approaches to the prevention of MAS have changed over time with collaboration between obstetricians and pediatricians forming the foundations for care. The use of surfactant and inhaled nitric oxide (iNO) has led to the decreased mortality and the need for extracorporeal membrane oxygenation (ECMO) use. In this paper, we review the current understanding of the pathophysiology and management of MAS.

Pigtail catheters used in the treatment of pneumothoraces in the neonate

Air leak in the neonatal population can be a deadly situation. Neonates have many risk factors that can contribute to air leak. These include, but are not limited to, respiratory distress syndrome; mechanical ventilation; sepsis; pneumonia; aspiration of meconium, blood, or amniotic fluid; and congenital malformations. In the NICU, the staff must be prepared to diagnose and treat pneumothoraces in a timely manner. Pathophysiology of air leaks in the neonate including the anatomy of the chest and diagnosis, indications, and common methods for the treatment of a pneumothorax in an infant is explained in this article. In addition, the latest form of treatment for neonates, known as the modified pigtail catheter, is described. A comprehensive literature review of the evidence behind the use of the pigtail catheter in neonates will be incorporated. Finally, the step-by-step placement of this catheter using the modified Seldinger technique will be illustrated and described in detail.

Versatile use of extra-corporeal life support to resuscitate acute respiratory distress patients

Extra-corporeal life support (ECLS) has been applied successfully to congenital respiratory defects but less optimally to acquired pulmonary failure. We extended this support to certain extreme complexities of patients with acute respiratory distress. From January 2003 to June 2005, 16 (nine men and seven women) patients refractory to ventilator support were treated with ECLS. Their median age was 32.4 years (1.5-70). The triggering events were pulmonary haemorrhage (n = 4), pneumonia (n = 7), aspiration (n = 2) and pancreatitis (n = 3). The indications for support were hypoxaemia in 13 and hypercapnia in three patients. Ten (63%) met the criteria of fast entry. Thirteen (81%) received veno-venous (V-V) mode support and the other three received veno-arterial mode support initially, but then converted to V-V mode after sufficient oxygenation stabilised haemodynamics. Initial pump flow was maximised to improve (mean 3250 +/- 1615 ml/min) to improve the oxygenation. Four patients with active pulmonary haemorrhage were heparin free in the first 12-24 h of support without complications. Excluding one prematurely terminated patient because of brain permanent damage, the duration of support was 162 +/- 95 h (67-363). Eleven (69%) weaned successfully from ECLS and 10 (63%) discharged and regained normal pulmonary performance in a median of 26.8 months follow-up. Pulmonary support using ECLS was feasible in selected patients with acute respiratory distress. Modification of guidelines for liberal use, early deployment before secondary organ damage and prevention of complications during support were the key to final success.

Seizures as a predictor of long-term neurodevelopmental outcome in survivors of neonatal extracorporeal membrane oxygenation (ECMO)

A longitudinal, prospective study was conducted to determine the long-term neurodevelopmental outcome in neonatal extracorporeal membrane oxygenation (ECMO) survivors with and without seizures. One hundred sixty-two ECMO survivors from March 1985 until November 1995 were eligible for follow-up. Sixty-four returned at preschool age (4-6 years). Thirty-nine infants did not experience neonatal seizures (group 1); however, 25 exhibited seizures before or during ECMO (group 2). Twelve infants referred for ECMO, but managed medically, served as a clinical comparison group (group 3). At school age (7-9 years), 32 ECMO children (16 with seizures) returned for neuropsychologic evaluation. The results indicated that the preschool seizure group (group 2) demonstrated a significantly lower mean IQ than group 1 or 3 (P = .002). Furthermore, 56% of group 2 had IQ scores < or =84 (> or =1 SD below the mean). Group 2 also exhibited significantly higher rates of cerebral palsy (P < or = .001) and speech-language disorder than group 1 or 3 (P < .001). At school age, the seizure group continued to perform below average on intelligence testing, with 50% scoring < or =84 and 38% receiving special education. This study extends the previous findings that seizures associated with neonatal ECMO are a primary risk factor for neurodevelopmental sequelae and confirms the need for long-term follow-up to assist with academic programming.

Venovenous versus venoarterial extracorporeal membrane oxygenation in congenital diaphragmatic hernia

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) has a significant role as a final rescue modality in severe respiratory failure of the newborn with congenital diaphragmatic hernia (CDH). The objective of this study was to compare the efficiency of venovenous (VV) versus venoarterial (VA) ECMO in newborns with CDH.

METHODS

A retrospective report of 11 years experience (1990 through 2001) of a single center, comparing VV and VA ECMO is given. VV ECMO was the preferred rescue modality for respiratory failure unresponsive to maximal medical therapy. Only when the placement of a VV ECMO 14F catheter was not possible, VA ECMO was used. Forty-six patients met ECMO criteria; 26 were treated with VV ECMO and 19 with VA ECMO. One patient underwent conversion from VV to VA ECMO.

RESULTS

Before ECMO, there was no difference between VV and VA ECMO patients in mean oxygenation index (83 v 83), mean airway pressure (18.4 v 18.9 cm H(2)O), ECMO cannulation age (28 v 20 hours), or in the percentage of patients who needed dopamine and dobutamine (100% v 100%). From November 1994, nitric oxide (NO) was available; before ECMO, 11 of 14 (79%) VV ECMO patients received NO versus 9 of 10 (90%) patients in the VA group. VV ECMO patients were larger (3.34 v 2.77 kg; P <.05) and of advanced gestational age (39.0 v 36.9 wk; P <.05) compared with VA ECMO patients. There was no significant difference between VV and VA ECMO patients in survival rate (18 of 26, 69% v 13 of 19, 68%), ECMO duration (152 v 150 hours), time of extubation (32.0 v 33.5 days), age at discharge (73 v 81 days), or incidence of short-term intracranial complications (3.8% v 10.5%) or myocardial stun (3.8% v 15.8%).

CONCLUSIONS

The authors conclude that VV ECMO is as reliable as VA ECMO in newborns with CDH in severe respiratory failure who need ECMO support and who can accommodate the VV double-lumen catheter. Because of its potential advantages, VV ECMO may be the preferred ECMO method in these infants.

Referral and transportation for neonatal extracorporeal membrane oxygenation

Data from 32 patients who were transported for neonatal extracorporeal membrane oxygenation (ECMO) over a 66-month period were reviewed. One ground ambulance transport had to be postponed because of poor weather conditions; the patient died. One patient was excluded for ECMO on arrival at the ECMO centre. Of the remaining 30 infants, 20 (67%) required ECMO treatment, of which four (20%) died. All 10 (33%) patients who were treated with conventional therapy survived. During transportation all children remained stable in terms of oxygenation. Early referral and transportation by an experienced and well-equipped transport team allows safe transport of these critically ill neonates.

The impact of changing neonatal respiratory management on extracorporeal membrane oxygenation utilization

BACKGROUND

The introduction of inhaled nitric oxide (INO) and high-frequency oscillatory ventilation (HFV) has had a profound effect on the use of extracorporeal membrane oxygenation (ECMO) for respiratory failure in neonates without congenital diaphragmatic hernia (CDH). The purpose of this study was to evaluate the changes in the demographics and outcome of non-CDH neonates who underwent ECMO for hypoxemic respiratory failure.

METHODS

All neonates (non-CDH and noncardiac) who underwent ECMO between January 1, 1989 and January 1, 2001 were reviewed. Patients were separated into 3, 4-year periods for comparison (period A, 1989 through 1992; B, 1993 through 1996; C, 1997 through 2000). Data were examined by analysis of variance and contingency table analysis.

RESULTS

There was a progressive decline in the total number of neonates requiring ECMO over time (period A, 172; B, 114; C, 56; P <.01). The utilization of pre-ECMO alternate respiratory therapies such as INO (period A, 0%; B, 23%; C, 98%; P <.01) and HFV (period A, 9%; B, 61%; C, 89%; P <.01) have increased significantly associated with an increase in the age of ECMO initiation (Period A, 40.5 hours; B, 58.3 hours; C, 68.5 hours; P <.01). The length of ECMO run also has increased (period A, 154.7 hours; B, 193.0 hours; C, 174.5 hours; P <.01), but the overall mortality rate has remained unchanged.

CONCLUSIONS

With the increasing use of INO and HFO, the absolute number of non-CDH, noncardiac neonates with hypoxemic respiratory failure requiring ECMO has decreased. Initiation of ECMO has become progressively later likely because of the use of these rescue therapies, but the overall mortality rate remains unchanged despite this delay.

Pharmacology for the gastrointestinal tract

A variety of drugs are used in the neonatal nursery for the management of feeding intolerance, gastroesophageal reflux, and acid-related disease. Although the pharmacokinetics of some of these drugs have been described in infants and older children, further data are needed, particularly for preterm infants. No data are available characterizing the disposition of the proton pump inhibitors, which will likely be used in infants with refractory, acid-related disease. Further data are also needed to characterize fully the pharmacodynamics, or efficacy, of many of the commonly used drugs.

The use of alteplase for the resolution of an intravesical clot in a neonate receiving extracorporeal membrane oxygenation

We present a case of the use of alteplase for the lysis of a large urinary bladder clot. A neonate presented with respiratory failure, secondary to a left diaphragmatic hernia necessitating the need for extracorporeal membrane oxygenation (ECMO) support. On day 3 of ECMO support, hematuria was noted, and a subsequent urinary bladder ultrasound revealed a significant urinary bladder clot. Alteplase (0.5-1 mg) was instilled into the urinary bladder via a 10 French Foley catheter (Sherwood Medical, St. Louis, MO). The catheter was clamped for 1 hour, followed by irrigation with normal saline. Multiple doses of alteplase were administered, resulting in complete resolution of the bladder clot. No adverse effects were attributed to the use of the intravesical alteplase. Alteplase seems to be safe and effective for the resolution of bladder clots, thereby potentially avoiding more invasive surgical procedures.

Hemodynamic changes during opening of the bridge in venoarterial extracorporeal membrane oxygenation

OBJECTIVE: To investigate the cause of the hemodynamic changes occurring during opening of the bridge in venoarterial (VA) extracorporeal membrane oxygenation (ECMO). DESIGN: Prospective intervention study in animals. SETTING: Animal research laboratory of a university medical center. SUBJECTS: Eight anesthetized lambs installed on VA-ECMO. INTERVENTIONS: During VA-ECMO the bridge was randomly opened during 1, 2.5, 5, 7.5, 10, and 15 secs at ECMO flow rates of 500, 400, 300, 200, 100, and 50 mL/min. Flows in the ECMO circuit between venous cannula and bridge and bridge and arterial cannula, mean arterial blood pressure, mean left carotid artery blood flow, central venous pressure, superior sagittal sinus pressure, inline mixed venous oxygen saturation, heart rate, and arterial oxygen saturation were measured continuously. Using near infrared spectrophotometry, changes in concentrations of cerebral oxygenated and deoxygenated hemoglobin and cerebral blood volume were also measured. Values during bridge opening were compared with values before opening. The same variables were determined with a roller pump on the bridge with a flow over the bridge at various flow rates. MEASUREMENTS AND MAIN RESULTS: Bridge opening resulted in a change of flow direction between venous cannula and bridge and bridge and arterial cannula. A biphasic response with initial decrease and secondary increase occurred in mean arterial blood pressure and mean left carotid artery blood flow. Central venous pressure, superior sagittal sinus pressure, deoxygenated hemoglobin, and cerebral blood volume increased, whereas cerebral oxygenated hemoglobin decreased. These effects occurred in each combination of ECMO flow rate and opening time. These effects could be abolished by installing a roller pump on the bridge. CONCLUSIONS: Bridge opening in VA-ECMO resulted in significant cerebral hemodynamic changes caused by an arteriovenous shunt over the bridge. The decreased cerebral perfusion pressure may contribute to the occurrence of cerebral ischemia, and the venous congestion may result in intracranial hemorrhages. These could be prevented by installing a roller pump on the bridge.

Predictors of acquiring a nosocomial bloodstream infection on extracorporeal membrane oxygenation

PURPOSE

The aim of this study was to identify independent predictors of acquiring a nosocomial bloodstream infection (BSI) during extracorporeal membrane oxygenation (ECMO).

METHODS

This retrospective cohort consisted of 202 neonates treated with ECMO from 1989 to 1998 at the author' institution. Data collected included patient demographics, primary and secondary diagnoses, white blood cell counts, antibiotic usage, presence of central lines, operative procedures, and outcome. Surveillance blood cultures were drawn daily from the circuit using sterile technique to identify acquired pathogens. Statistical analyses included logistic regression, Cox proportional regression analysis, and discriminate analysis.

RESULTS

There were 1,245 blood cultures drawn on 202 patients (6.2 cultures per patient), and a nosocomial BSI was identified in 7 patients (3.4%) during this 10-year span. These were infections that were neither present nor incubating on admission. Pre-ECMO diagnoses of patients who had a nosocomial BSI while on bypass included group B beta-hemolytic streptococcal sepsis (n = 2), herpes simplex viral sepsis (n = 1), congenital diaphragmatic hernia (n = 2), persistent pulmonary hypertension (n = 1), and congenital heart disease (n = 1). The median time on ECMO before obtaining a positive culture was 390 hours. The infectious agents responsible for these BSIs included Staphylococcus epidermidis (n = 5), Staphylococcus aureus (n = 1), and Escherichia coli (n = 1). The major factor associated with acquiring a nosocomial BSI on ECMO was the duration of bypass (391 v 141 hours, P =.002). Additionally, patients in the BSI group were more likely to have had an arterial catheter in place (16 v 7 days, P =.009) and to have received more screening blood cultures (16 v 6 cultures, P < 001). White blood cell counts, absolute neutrophil counts, and immature/total (I/T) ratios were not useful in predicting a nosocomial BSI. Of the 31 patients who required ECMO for more than 10 days, 7 (23%) had a positive blood culture, and 5 of these 7 infants (71%) died (P =.03).

CONCLUSIONS

The only predictor of acquiring a nosocomial BSI on ECMO was the duration of support for greater than 10 days. Because classical predictors of infection are unreliable while the patient is on ECMO, the authors suggest that obtaining daily surveillance blood cultures beginning on the tenth day should be performed with prolonged ECMO courses. The authors confirmed previous reports of the association between a prolonged ECMO course and a high mortality rate. However, the authors speculate that, in actuality, the primary diagnosis leads to the prolonged course of support and is the major factor in the infant' demise.

The changing demographics of neonatal extracorporeal membrane oxygenation patients reported to the Extracorporeal Life Support Organization (ELSO) Registry

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is an important treatment tool in the management of near-term and term neonates with severe hypoxemic respiratory failure. To better understand how health care for patients treated with ECMO has changed, we studied the demographic and treatment data reported to the Extracorporeal Life Support Organization (ELSO) registry from January 1, 1988, through January 1, 1998.

METHODS

We used data stored in the ELSO registry and evaluated the changes in demographics, use of alternate therapies before ECMO, severity of illness, duration of ECMO therapy, and mortality over a 10-year period. All data on neonates reported between January 1, 1988, and January 1, 1998 were used. Verification checks were performed on all fields to eliminate nonsense outliers. We separated the neonates into 2 groups-those with and those without a congenital diaphragmatic hernia (CDH). All analyses were performed on the total group and each subgroup separately. Changes in continuous data were analyzed by year using analysis of variance. Year differences in categorical data were evaluated with chi(2) analysis. We also used the linear trend test and the Cochran-Armitage trend test to evaluate time-related changes.

RESULTS

We reviewed 12 175 neonates. Over the decade, there were no changes in mean gestational age, gender, age at which ECMO was started, pH, or PaCO(2) just before ECMO. The proportion of neonates with CDH increased from 18% to 26%, while the proportion with respiratory distress syndrome decreased from 15% to 4%. Other diagnostic categories remained constant. The use of surfactant, high-frequency ventilation, and inhaled nitric oxide increased from 0% in 1988 to 36%, 46%, and 24%, respectively, in 1997. The mean peak pressure being used just before ECMO decreased (47 +/- 10 in 1988 to 39 +/- 12 in 1997), and the mean PaO(2)/FIO(2) ratio increased (38 +/- 23 in 1988 to 48 +/- 36 in 1997). The primary mode of ECMO remains venoarterial; however, the use of venovenous ECMO increased from 1% to 32% over the decade. Duration of ECMO treatment increased overall, and this trend was seen for patients with and without CDH (124 +/- 67 to 141 +/- 104 hours for the non-CDH group, 161 +/- 99 to 238 +/- 141 hours for the CDH group). The number of centers reporting neonatal data to the ELSO registry increased from 52 in 1988 to a peak of 100 in 1993. In 1997, 96 centers reported data to ELSO. The average number of neonatal patients reported from each site decreased from a peak of 18 in 1991 to 9 in 1997. Mortality increased from 18% to 22%; however, when corrected for the relative increase in neonates with CDH, this trend disappeared. Diagnoses-specific mortality rates remained constant. The occurrence of intracranial hemorrhage and/or infarct also stayed constant at 16%.

CONCLUSIONS

The population of neonates treated with ECMO in 1997 was very different from patients treated in the 1980s and early 1990s. They were exposed to an ever-expanding group of new therapies, appeared to be healthier based on indices of gas exchange, and were cared for at centers that reported fewer cases per year.

Inhaled nitric oxide in the management of persistent pulmonary hypertension of the newborn: a meta-analysis

OBJECTIVES

To evaluate the use of inhaled nitric oxide (NO) in the management of persistent pulmonary hypertension of the newborn.

METHODS

Computerized bibliographic search on MEDLINE, CURRENT CONTENTS and LILACS covering the period from January 1990 to March 1998; review of references of all papers found on the subject. Only randomized clinical trials evaluating nitric oxide and conventional treatment were included. OUTCOMES STUDIED: death, requirement for extracorporeal membrane oxygenation (ECMO), systemic oxygenation, complications at the central nervous system and development of chronic pulmonary disease. The methodologic quality of the studies was evaluated by a quality score system, on a scale of 13 points.

RESULTS

For infants without congenital diaphragmatic hernia, inhaled NO did not change mortality (typical odds ratio: 1.04; 95% CI: 0.6 to 1.8); the need for ECMO was reduced (relative risk: 0.73; 95% CI: 0.60 to 0.90), and the oxygenation was improved (PaO2 by a mean of 53.3 mm Hg; 95% CI: 44.8 to 61.4; oxygenation index by a mean of -12.2; 95% CI: -14.1 to -9.9). For infants with congenital diaphragmatic hernia, mortality, requirement for ECMO, and oxygenation were not changed. For all infants, central nervous system complications and incidence of chronic pulmonary disease did not change.

CONCLUSIONS

Inhaled NO improves oxygenation and reduces requirement for ECMO only in newborns with persistent pulmonary hypertension who do not have diaphragmatic hernia. The risk of complications of the central nervous system and chronic pulmonary disease were not affected by inhaled NO.

Neurodevelopmental outcome at 3.5 years of age in children treated with extracorporeal life support: relationship to primary diagnosis

OBJECTIVE

Recent studies suggest that for neonates treated with extracorporeal membrane oxygenation (ECMO), children with congenital diaphragmatic hernia (CDH) have poorer neurodevelopmental outcome than children with other diagnoses. We therefore analyzed the neurodevelopmental outcome at 3(1/2) years of age in 130 neonatal ECMO survivors with 6 different primary diagnoses.

STUDY DESIGN

Children were assessed with the McCarthy Scales of Children's Abilities, Peabody Picture Vocabulary Test, Vineland Adaptive Behavior Scales, and a neurologic/physical examination; 12 factors related to infant characteristics and ECMO/hospital course including primary diagnosis were identified as independent variables. Dependent variables included test scores and 2 outcome categories: functional status (normal, risk, abnormal) and major neurologic sequelae (presence or absence). Statistical tools included chi-squared analysis, t test, analysis of variance, and discriminant and regression analysis.

RESULTS

No significant differences were found between diagnostic groups in functional status or neurologic sequelae. Hospital days was the only variable consistently expressed in all analyses as having significant influence on the outcome measures. This was not a factor of the longer hospital days experienced by children with CDH.

CONCLUSION

Neurodevelopmental outcome in neonatal ECMO is multifactorial. Although hospital days has the greatest association with outcome at age 3(1/2) years, these days likely reflect degree of illness and various complications that are independent of diagnostic group. Further study is required to determine which factors influencing the length of hospital stay may be the best predictor of long-term outcome.

Low-dose nitric oxide therapy for persistent pulmonary hypertension of the newborn. Clinical Inhaled Nitric Oxide Research Group

BACKGROUND

Inhaled nitric oxide improves gas exchange in neonates, but the efficacy of low-dose inhaled nitric oxide in reducing the need for extracorporeal membrane oxygenation has not been established.

METHODS

We conducted a clinical trial to determine whether low-dose inhaled nitric oxide would reduce the use of extracorporeal membrane oxygenation in neonates with pulmonary hypertension who were born after 34 weeks' gestation, were 4 days old or younger, required assisted ventilation, and had hypoxemic respiratory failure as defined by an oxygenation index of 25 or higher. The neonates who received nitric oxide were treated with 20 ppm for a maximum of 24 hours, followed by 5 ppm for no more than 96 hours. The primary end point of the study was the use of extracorporeal membrane oxygenation.

RESULTS

Of 248 neonates enrolled, 126 were randomly assigned to the nitric oxide group and 122 to the control group. Extracorporeal membrane oxygenation was used in 78 neonates in the control group (64 percent) and in 48 neonates in the nitric oxide group (38 percent) (P=0.001). The 30-day mortality rate in the two groups was similar (8 percent in the control group and 7 percent in the nitric oxide group). Chronic lung disease developed less often in neonates treated with nitric oxide than in those in the control group (7 percent vs. 20 percent, P=0.02). The efficacy of nitric oxide was independent of the base-line oxygenation index and the primary pulmonary diagnosis.

CONCLUSIONS

Inhaled nitric oxide reduces the extent to which extracorporeal membrane oxygenation is needed in neonates with hypoxemic respiratory failure and pulmonary hypertension.

The use of alteplase in a newborn receiving extracorporeal membrane oxygenation

OBJECTIVE

To present a case of the use of alteplase for the successful resolution of an upper extremity occlusion in a newborn receiving extracorporeal membrane oxygenation (ECMO).

CASE SUMMARY

A two-day-old full-term Hispanic girl receiving ECMO support developed a left upper extremity occlusion distal to the brachial artery. Alteplase therapy was initiated with a bolus dose of 0.48 mg/kg followed by a continuous infusion of 0.27 mg/kg/h for three hours. A repeat Doppler ultrasound revealed little improvement, resulting in continuation of alteplase therapy at an infusion rate of 0.27 mg/kg/h for an additional three hours. At the completion of the infusion, perfusion was greatly improved with palpable radial pulse present. While remaining on ECMO support, a brain ultrasound approximately 13 hours after alteplase therapy revealed a grade I right caudate head hemorrhage with normal ventricles. ECMO support was discontinued during the next 24 hours, with a repeat brain ultrasound three days later indicating no acute hemorrhage, normal ventricles, and almost complete resolution of the intraventricular hemorrhage. The neonate was discharged 19 days after discontinuing ECMO support.

DISCUSSION

Patients receiving ECMO support are at risk of hematologic complications, including thrombi formation. Moreover, limited information is available regarding the most appropriate thrombolytic therapy for patients receiving ECMO support. Alteplase is an attractive thrombolytic agent given its antigenicity, clot specificity, and pharmacokinetic profile. However, both ECMO support and thrombolytic therapy are risk factors for the development of intraventricular hemorrhage, which our patient developed. Therefore, close monitoring of patients receiving ECMO support and alteplase therapy is essential given the potential for hematologic adverse effects.

CONCLUSIONS

Alteplase is an effective thrombolytic agent in neonates receiving ECMO support. Additional experience with alteplase is necessary to determine the optimal dose and duration of therapy in this patient population.

Phenobarbital dosing and pharmacokinetics in a neonate receiving extracorporeal membrane oxygenation

OBJECTIVE

To describe the dosing and pharmacokinetics of phenobarbital in a neonate receiving extracorporeal membrane oxygenation (ECMO).

CASE SUMMARY

The treatment of a 2.6 kg, 38-week gestational age boy with congenital diaphragmatic hernia who developed seizures while receiving ECMO support is described. A loading dose of 20 mg/kg resulted in concentrations of 16.4 and 12.9 micrograms/mL at 3 and 24 hours, respectively. A maintenance dose of 5 mg/kg/d provided a peak concentration of 19.7 micrograms/mL and trough concentration of 16.7 micrograms/mL after four doses. The calculated volume of distribution was 1.2 L/kg and the estimated elimination half-life was 92 hours. Serum concentrations decreased after circuit changes unless the new circuit was redosed.

DISCUSSION

The reported incidence of seizures in neonates while receiving ECMO support is 18%. Despite this frequency, there are no clinical reports describing anticonvulsant use in this population. This case demonstrates the use of standard phenobarbital doses to achieve low, but therapeutic, serum concentrations. Pharmacokinetic analysis revealed a volume of distribution slightly larger than expected in neonates and an elimination half-life similar to published values. Altering circulating blood volumes resulted in significant reductions in serum concentrations.

CONCLUSIONS

Neonates on ECMO may have a larger volume of distribution than neonates not receiving ECMO and may require larger phenobarbital doses to achieve desired serum concentrations. This may result from the presence of large exogenous blood volumes for priming, as well as loss of drug during circuit changes, extraction by the circuit, or hemofiltration. Further work is needed to better define the pharmacokinetics and pharmacodynamics of phenobarbital in the neonatal ECMO population.

Efficacy and complications of percutaneous pigtail catheters for thoracostomy in pediatric patients

OBJECTIVE

To describe the efficacy of percutaneous pigtail catheters in evacuating pleural air or fluid in pediatric patients.

DESIGN

A case series of children with percutaneous pigtail catheters placed in the pediatric ICU between January 1996 and August 1997.

SETTING

Urban pediatric teaching hospital in Seattle, WA.

METHODS

A retrospective chart review.

RESULTS

Ninety-one children required 133 chest catheters. Most patients were infants with congenital heart disease (80%). One hundred thirteen of the catheters (85%) were placed for pleural effusion, with 20 tubes (15%) placed for pneumothorax. Efficacy of drainage of pleural fluid was significantly greater in serous (96%) and chylous (100%) effusions compared with empyema (0%) or hemothorax (81%). Evacuation of pneumothorax was achieved by a pigtail catheter in 75% of patients. Resolution of pleural air or pneumothorax was significantly greater in patients < 10 kg compared with larger children. Complications due to placement of the pigtail catheters included hemothorax (n=3, 2%), pneumothorax (n=3, 2%), and hepatic perforation (n= 1, 1%). There were also complications arising from the use of the catheters, including failure to drain, dislodgment, kinking, loss of liquid ventilation fluid, empyema, and disconnection in 27 of 133 catheters (20%). Significantly more complications during catheter use occurred in patients <5 kg than in larger children.

CONCLUSIONS

Percutaneous pigtail catheters are highly effective in drainage of pleural serous and chylous effusions, somewhat less efficacious in drainage of hemothorax or pneumothorax, and least efficacious in drainage of empyema. Infants and smaller children had higher rates of resolution of pleural air and fluid from placement of a pigtail catheter than larger children. Complications from catheter placement were uncommon (5%) but serious, whereas complications associated with continued use of the catheters were more common (20%) but less grave. Strict attention to anatomic landmarks and close monitoring may reduce the number of complications.

Cardiovascular complications adversely affect survival during extracorporeal membrane oxygenation

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) has been used in the management of infants with cardiorespiratory failure. ECMO causes a decrease in load-dependent measures of cardiac performance that have not been demonstrated to affect patient outcome, while other cardiovascular complications occur which may affect outcome. The purpose of this study was to describe the cardiovascular complications associated with ECMO, and to determine their relationship to survival.

DESIGN

Data were obtained, retrospectively, from the medical records of 500 consecutive newborns treated with ECMO at our institution since 1984.

RESULTS

Hypertension (mean arterial pressure of >65 mm Hg) was the most common complication, requiring medical intervention in 192 infants. Myocardial stun, the near-total absence of systolic function during ECMO, occurred in 59 infants. Rhythm abnormalities, including noncannulation-related bradycardia, occurred in 43 infants, cardiac arrest, and pericardial effusion in 17 infants, and noninfective thrombosis in 9 infants. Only one infant required ligation of a patent ductus arteriosus during ECMO. Infants with at least one cardiovascular complication had a lower survival rate, compared with those infants without a complication. Survival rates were decreased in infants with myocardial stun, arrhythmia, and cardiac arrest. Hypertension and pericardial effusion were not associated with decreased survival.

CONCLUSION

These findings suggest that some cardiovascular complications during ECMO are more common than previously thought, and cardiovascular complications may adversely impact outcome.

Pharmacokinetics and pharmacodynamics of ranitidine in neonates treated with extracorporeal membrane oxygenation

The pharmacokinetics and pharmacodynamics of ranitidine were studied in 13 term neonates with stable renal and hepatic function who were treated with extracorporeal membrane oxygenation (ECMO). Ranitidine was initially administered as a single 2 mg/kg dose over 10 minutes and intragastric pH was monitored to determine response. Within 90 minutes after administration of ranitidine, intragastric pH for all of the patients whose initial reading was < or = 4 had increased to > 5. Intragastric pH remained > 4 for a minimum of 15 hours. Mean +/- 1 standard deviation elimination half-life was 6.61 +/- 2.75 hours, and 41.5 +/- 22.2% of the single dose was eliminated in urine within 24 hours. Total plasma clearance of ranitidine correlated well with estimated glomerular filtration rate. Twenty-four hours after the initial dose, a continuous infusion of ranitidine (2 mg/kg/24 hr) was started and continued for 72 hours or until ECMO was discontinued. Eleven patients completed 48 hours of continuous infusion and seven completed all 72 hours. Plasma clearance and elimination half-life were determined from steady-state plasma ranitidine concentrations 24, 48, and 72 hours after the start of the infusion. There were no significant differences in clearance between these intervals. These data suggest that for term neonates with stable renal and hepatic function, ranitidine does not need to be administered more frequently than every 12 hours. A continuous infusion of 2 mg/kg/24 hours maintained intragastric pH above 4 in more than 90% of our patients, and in our opinion is the preferred method for delivering ranitidine to term neonates undergoing ECMO who require H2 antagonists. Response to therapy should be monitored by repeated measurement of gastric pH and the dose should be adjusted accordingly.

Inhaled nitric oxide for the early treatment of persistent pulmonary hypertension of the term newborn: a randomized, double-masked, placebo-controlled, dose-response, multicenter study. The I-NO/PPHN Study Group

OBJECTIVES

To assess the dose-related effects of inhaled nitric oxide (I-NO) as a specific adjunct to early conventional therapy for term infants with persistent pulmonary hypertension (PPHN), with regard to neonatal outcome, oxygenation, and safety.

METHODS

Randomized, placebo-controlled, double-masked, dose-response, clinical trial at 25 tertiary centers from April 1994 to June 1996. The primary endpoint was the PPHN Major Sequelae Index ([MSI], including the incidence of death, extracorporeal membrane oxygenation (ECMO), neurologic injury, or bronchopulmonary dysplasia [BPD]). Patients required a fraction of inspired oxygen [FIO2] of 1.0, a mean airway pressure >/=10 cm H2O on a conventional ventilator, and echocardiographic evidence of PPHN. Exogenous surfactant, concomitant high-frequency ventilation, and lung hypoplasia were exclusion factors. Control (0 ppm) or nitric oxide (NO) (5, 20, or 80 ppm) treatments were administered until success or failure criteria were met. Due to slowing recruitment, the trial was stopped at N = 155 (320 planned).

RESULTS

The baseline oxygenation index (OI) was 24 +/- 9 at 25 +/- 17 hours old (mean +/- SD). Efficacy results were similar among NO doses. By 30 minutes (no ventilator changes) the PaO2 for only the NO groups increased significantly from 64 +/- 39 to 109 +/- 78 Torr (pooled) and systemic arterial pressure remained unchanged. The baseline adjusted time-weighted OI was also significantly reduced in the NO groups (-5 +/- 8) for the first 24 hours of treatment. The MSI rate was 59% for the control and 50% for the NO doses (P = .36). The ECMO rate was 34% for control and 22% for the NO doses (P = .12). Elevated methemoglobin (>7%) and nitrogen dioxide (NO2) (>3 ppm) were observed only in the 80 ppm NO group, otherwise no adverse events could be attributed to I-NO, including BPD.

CONCLUSION

For term infants with PPHN, early I-NO as the sole adjunct to conventional management produced an acute and sustained improvement in oxygenation for 24 hours without short-term side effects (5 and 20 ppm doses), and the suggestion that ECMO use may be reduced.

Emergency extracorporeal life support for patients with near-fatal status asthmaticus

Extracorporeal life support (ECLS) was used to treat three patients with near-fatal status asthmaticus who did not respond to aggressive medical therapies and mechanical ventilation under controlled permissive hypercapnia. ECLS was instituted in patient 1 because PaCO2 was excessively high and pH was excessively low, in patient 2 because hypoxemia and shock were not responsive to treatment, and in patient 3 because of sustained severe hypotension. ECLS supported adequate gas exchange until pulmonary function improved, diminishing the need for mechanical ventilation and preventing pulmonary complications. Pulmonary dysfunction improved markedly after only 21 to 86 hours of ECLS. Aggressive medical treatments were continued during ECLS. Our findings indicate that ECLS is a useful method for preventing death in patients with near-fatal status asthmaticus.

Arch growth after staged repair of interrupted aortic arch using carotid artery interposition

BACKGROUND

Between 1980 and 1990, our practice was to perform carotid artery interposition as part of a staged repair of interrupted aortic arch with various associated cardiac defects.

METHODS

This procedure was used in 16 patients with IAA type B. The median age at operation was 4.5 days and the median weight, 3.2 kg. Ten of the patients had an associated ventricular septal defect. Six more had complex anatomy. There were two death at carotid interposition, two interim deaths, and two deaths after intracardiac repair. Preoperative echocardiographic and angiographic studies were compared with postoperative studies in 11 survivors of arch repair to assess sequential growth of the interposed carotid artery. Measurements of the carotid artery were normalized to the descending aorta.

RESULTS

Preoperatively, the left carotid artery had a median diameter of 3.7 mm and was 42.9% of the descending aortic diameter. Postoperative studies performed at a median age of 5.7 months disclosed that the interposed carotid artery had grown to a median diameter of 7.0 mm and was 69.6% of the diameter of the descending aorta (normal > or = 81%). On follow-up at a median time of 4 years, 6 of 9 patients have no gradient by blood pressure measurements or echocardiographic Doppler studies, and 3 have modest gradients. No patient has required revision of the arch repair.

CONCLUSIONS

Survival is good after carotid artery interposition for interrupted aortic arch and growth of the carotid artery approaches that of a normal arch. Carotid artery interposition is a viable alternative for repair of this lesion should primary definitive repair not be feasible.

Sensitivity and specificity of the neonatal brain-stem auditory evoked potential for hearing and language deficits in survivors of extracorporeal membrane oxygenation

OBJECTIVE

We determined the sensitivity and specificity of neonatal brain-stem auditory evoked potentials (BAEP) as markers for subsequent hearing impairment and for developmental problems found later in infancy and childhood.

METHODS

BAEP studies were performed before discharge in infants treated with extracorporeal membrane oxygenation (ECMO), and two specific abnormalities were analyzed: elevated threshold and delayed central auditory conduction. Behavioral audiometry was repeated during periodic follow-up until reliable responses were obtained for all frequencies, and standardized developmental testing was also conducted. The sensitivity and specificity of an elevated threshold on the neonatal BAEP for detecting subsequent hearing loss, and the relationship of any neonatal BAEP abnormality to language or developmental disorders in infancy, were calculated.

RESULTS

Test results for 46 ECMO-treated infants (57.5%) were normal, and those for 34 infants (42.5%) were abnormal, with either elevated wave V threshold, prolonged wave I-V interval, or both on neonatal BAEP recordings. Most significantly, 7 (58%) of the 12 children with subsequent sensorineural hearing loss had left the hospital after showing normal results on threshold tests. There was no significant difference in the frequency of hearing loss between subjects with abnormal (5/21, or 24%) and those with normal BAEP thresholds (7/59, or 12%; Fisher Exact Test, p = 0.28). Therefore the sensitivity of neonatal BAEP testing for predicting subsequent hearing loss was only 42%. Neonatal BAEP specificity for excluding subsequent hearing loss was 76%. In contrast, on language development testing, 19 children demonstrated receptive language delay. Of these children, 12 (63%) had abnormal neonatal BAEP recordings and 7 (37%) had a normal BAEP threshold, normal central auditory conduction test results, or both (p = 0.04).

CONCLUSIONS

Neonatal BAEP threshold recordings were of limited value for predicting subsequent hearing loss common in ECMO-treated survivors. However, an abnormal neonatal BAEP significantly increased the probability of finding a receptive language delay during early childhood, even in those with subsequently normal audiometry findings. Because neonatal ECMO is associated with a high risk of hearing and receptive language disorders, parents should be counseled that audiologic and developmental follow-up evaluations in surviving children are essential regardless of the results of neonatal BAEP testing.

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.

Longitudinal follow-up of a cohort of newborn infants treated with inhaled nitric oxide for persistent pulmonary hypertension

OBJECTIVE

To describe the outcome of a group of term newborn infants treated with inhaled nitric oxide for severe persistent pulmonary hypertension.

STUDY DESIGN

We performed a prospective longitudinal medical and neurodevelopmental follow-up of 51 infants treated as neonates for persistent pulmonary hypertension of the newborn with inhaled nitric oxide. The original number of treated infants was 87, of whom 25 died in the neonatal period; of 62 infants who survived, 51 were seen at 1 year of age and 33 completed a 2-year evaluation. Statistical analysis used population medians, means, and standard deviations for parameters assessed. Paired t tests and chi-square analysis were used to compare outcomes measured at 1 year with assessment at 2 years for the 32 infants seen at both 1- and 2-year visits.

RESULTS

At 1-year follow-up median growth percentiles were 20%, 72.5%, and 50% for weight, length, and occipitofrontal circumference, respectively. Thirteen of 51 infants (25.5%) were < 5th percentile in weight. Nine of 51 infants (17.6%) had feeding problems (need for gastrostomy feeding or gastroesophageal reflux), and 14 (27.5%) had a clinical diagnosis of reactive airways disease. Infant development as measured by the Bayley Scales of Infant Development was 104 +/- 16 for the mental development index and 97 +/- 20 for the psychomotor index. Six of 51 infants (11.8%) were found to have severe neurologic handicaps, defined as a Bayley score on either the mental development or psychomotor index of < 68, abnormal findings on neurologic examination, or both. Fewer children (6.1% vs 15.7%) required supplemental oxygen at 2 years compared with 1 year, and performance on the psychomotor index of the Bayley Scales improved significantly.

CONCLUSIONS

One- and 2-year follow-up of a cohort of infants with persistent pulmonary hypertension of the newborn who were treated with inhaled nitric oxide had an 11.8% (1 year) and 12.1% (2-year) rate of severe neurodevelopmental disability. There are ongoing medical problems in these infants including reactive airways disease and slow growth that merit continued close longitudinal follow-up.

Retinal examinations in infants after extracorporeal membrane oxygenation

BACKGROUND

Ophthalmic examinations performed in infants undergoing extracorporeal membrane oxygenation (ECMO) are recommended because ocular abnormalities have been known to occur after this procedure.

METHODS

We reviewed medical records of infants treated with ECMO was subsequently underwent routine ophthalmic examination prior to or immediately after hospital discharge. Examinations were performed in a fashion similar to that for retinopathy of prematurity screening.

RESULTS

Eye examinations were recorded for 171 patients (342 eyes). Fundus examination was normal in 302 eyes (88%). Abnormal retinovascular findings such as venous dilation or intraretinal hemorrhages, when present, were not considered vision threatening and required no treatment.

CONCLUSION

Clinically important retinal findings were not identified in our patients undergoing postECMO screening. Routine dilated fundus examination is probably not cost effective and places additional and potentially unnecessary stress on these infants.

The safety of a nitric oxide inhalation system with high frequency oscillatory ventilation

Nitric oxide (NO) inhalation and high frequency oscillatory ventilation (HFOV) has been indicated in infants with severe respiratory failure. The purpose of the present study was to evaluate the safety of an NO inhalation system with HFOV in terms of nitrogen dioxide (NO2) production. The NO inhalation system consisted of a high frequency oscillatory ventilator, a neonatal circuit and a test lung. The NO concentration was changed from 0 to 19 p.p.m. At each level of NO, the oxygen (O2) concentration was changed from 21 to 100%. The NO and NO2 concentrations were measured with a chemiluminescence analyzer using a molybdenum converter. The NO2 concentration was increased when either the O2 or the NO concentration was increased. The interposition of the endotracheal tubes increased NO2 concentrations at 4 p.p.m. NO. The high stroke volume and high mean airway pressure produced a significant increase in NO2 production at 4 p.p.m. NO. The increase in NO2 production was prevented by placing a one-way valve at the joint of the NO gas line to the inspired limb. It was concluded that the NO inhalation system with HFOV can be safely used when a one-way valve is placed at the joint of the NO gas line to the inspired limb and when inhaled NO is at a relatively low concentration.

The use of extracorporeal membrane oxygenation in patients with gram-negative or viral sepsis

To evaluate the use of extracorporeal membrane oxygenation (ECMO) in patients with Gram-negative or viral sepsis, a survey of ECMO centres comprising the Extracorporeal Life Support Organization was conducted. Data collected from neonatal and paediatric intensive care units included patient demographics, indicators of infection, presence of cardiac instability and respiratory criteria for ECMO. One-hundred-and-seven patients with documented sepsis were divided into survivors and nonsurvivors. Prior to ECMO, the patients with a persistent metabolic acidosis (p < 0.008) and/or hypotension requiring more than two inotropic agents (p < 0.02) to support blood pressure were less likely to survive. Also, patients with Gram-positive infections (77%) were more likely to survive their ECMO course than those with Gram-negative (60%) or viral infections (40%). Although survival is less in septic infants than in infants with traditional respiratory failure placed on ECMO, sepsis should not be a contraindication to the use of ECMO. The parents should be informed of the chances of survival with each type of sepsis or respiratory infection (if known), so that a truly informed decision can be made by the parents. We feel that the additional information regarding Gram-negative and viral sepsis should assist the clinician in this goal.

Principles and Practice of Venovenous Extracorporeal Membrane Oxygenation

Over the past several years, the use of venovenous extracorporeal membrane oxygenation (ECMO) has increased. The primary advantage of venovenous (VV) over venoarterial (VA) ECMO is preservation of the carotid artery. Its primary disadvantage is that it does not provide circulatory support. While VV ECMO is technically similar to VA ECMO, clinical application of VV ECMO is quite different from VA ECMO. Recent clinical data show that VV ECMO is safe and effective. The purpose of this review is to discuss these differences between VV and VA ECMO, to review the various forms of VV ECMO, and finally to offer recommendations on the safe clinical use of VV ECMO.

Simulation models in the planning of health care facilities: an application in the case of neonatal extracorporeal membrane oxygenation

OBJECTIVES

To investigate whether modelling techniques can be used in the planning of health care facilities for patients requiring neonatal extracorporeal membrane oxygenation (ECMO).

METHODS

In a micro-simulation model the number of patients that will have to be referred to facilities abroad is estimated for any number of neonatal ECMO patients presenting annually for treatment in The Netherlands, and any number of ECMO facilities. The inputs to the model consist of the number of ECMO facilities, the number of patients presenting annually, the duration of treatment and the date on which patients present for ECMO treatment. The model is estimated on data from The Netherlands for 1992, during which 29 patients were treated in three facilities. Several future scenarios are modelled, principally one in which a potential increase to 56 patients per year is foreseen.

RESULTS

The model indicates that, if such an increase takes place, no additional ECMO facilities will be necessary in The Netherlands if between three and four referrals annually to centres outside the region (or abroad) are considered acceptable and feasible. In that situation, it is expected that on 22 occasions each year two patients will be treated simultaneously, for a total of 81 days. On ten occasions, all three facilities will be occupied at the same time, for 21 days in total. On 199 days, at least one of the facilities will be occupied.

CONCLUSION

The current study shows that the acceptability and feasibility of patient referrals to ECMO centres abroad is an important issue which health care planners will have to consider. The study also shows that modelling techniques can provide information that is useful to policy-makers in the planning of health care facilities.

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.