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

Developing a new pediatric extracorporeal membrane oxygenation (ECMO) program

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Role of extracorporeal membrane oxygenation in pediatric cancer patients: a systematic review and meta-analysis of observational studies

Background

The use of extracorporeal membrane oxygenation (ECMO) in pediatric patients with underlying malignancies remains controversial. However, in an era in which the survival rates for children with malignancies have increased significantly and several recent reports have demonstrated effective ECMO use in children with cancer, we aimed to estimate the outcome and complications of ECMO treatment in these children.

Methods

We searched MEDLINE, Embase and CINAHL databases for studies on the use ECMO in pediatric patients with an underlying malignancy from inception to September 2020. This review was conducted in adherence to Preferred Reporting Items for Systematic Review and Meta-Analysis statement. Study eligibility was independently assessed by two authors and disagreements resolved by a third author. Included studies were evaluated for quality using the Newcastle–Ottawa Scale (NOS). Random effects meta-analyses (DerSimonian and Laird) were performed. The primary outcomes were mortality during ECMO or hospital mortality.

Results

Thirteen retrospective, observational cohort studies were included, most of moderate quality (625 patients). The commonest indication for ECMO was severe respiratory failure (92%). Pooled mortality during ECMO was 55% (95% confidence interval [CI], 47–63%) and pooled hospital mortality was 60% (95% CI 54–67%). Although heterogeneity among the included studies was low, confidence intervals were large. In addition, the majority of the data were derived from registries with overlapping patients which were excluded for the meta-analyses to prevent resampling of the same participants across the included studies. Finally, there was a lack of consistent complications reporting among the studies.

Conclusion

Significantly higher mortalities than in general PICU patients was reported with the use of ECMO in children with malignancies. Although these results need to be interpreted with caution due to the lack of granular data, they suggest that ECMO appears to represents a viable rescue option for selected patients with underlying malignancies. There is an urgent need for additional data to define patients for whom ECMO may provide benefit or harm.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-00983-0.

Intensivtransport Neugeborener mit respiratorischem Versagen

Hintergrund und Ziel der Studie

Der Transport von Früh und Neugeborenen mit respiratorischem Versagen ist mit einem hohen Transportrisiko assoziiert und stellt höchste Anforderungen an medizinisches Personal und technische Ausrüstung. Eine kontinuierliche Überprüfung der Qualität ist daher unumgänglich. Ziel dieser monozentrischen retrospektiven Analyse ist es, die Mortalität transportierter Neugeborener mit respiratorischem Versagen mithilfe eines Outcomescores, Transport Risk index of Physiologic Stability, Version II, (TRIPS-II-Score) und im Vergleich zu bereits publizierter Literatur zu analysieren.

Methodik

Es wurden 79 Intensivtransporte von Früh- und Neugeborenen mit hochgradigem respiratorischem Versagen retrospektiv analysiert. Zur Einschätzung des Transportrisikos und der Transportqualität wurde der TRIPS-II-Score erhoben und mit der Literatur verglichen.

Ergebnisse

Insgesamt wurden 77 Patienten luft- (n = 56, 73 %) oder bodengebunden (n = 21, 27 %) transportiert. Zwei Patienten verstarben vor dem Transport. Kein Patient verstarb während des Transports. Alle Patienten mussten invasiv beatmet werden, davon 22 (29 %) mit Hochfrequenzoszillation (HFOV) und 55 (71 %) erhielten inhalatives Stickoxid (iNO). Der mittlere Oxygenierungsindex (OI) betrug 33 [4-100, min.-max.] Insgesamt mussten 24 Patienten (31 %) nach Aufnahme einer ECMO-Therapie unterzogen werden. Insgesamt verstarben 20 (26 %) Neugeborene, 7 davon in der ECMO-Therapie-Gruppe.

Schlussfolgerung

Transporte von Neugeborenen mit schwerem Lungenversagen können durch den Einsatz eines spezialisierten Teams mit Sonderequipment meist komplikationslos durchgeführt werden. Die scheinbar sehr hohe Mortalität ist mit Daten der internationalen Literatur vergleichbar.

Diffuse Alveolar Damage Correlation with Clinical Diagnosis of Pediatric Acute Respiratory Distress Syndrome

Diffuse alveolar damage (DAD) is one of the pathological hallmarks of acute respiratory distress syndrome (ARDS). We aimed to compare pathological findings of DAD with clinical ARDS criteria. We re-evaluated 20 patients whose clinical autopsy revealed DAD. Total 11/20 patients with DAD (55%) met the 1994 American-European Consensus Conference and 7/17 (41%) met the 2012 Berlin clinical criteria. DAD showed only moderate correlation with current clinical ARDS definition. Oxygenation index (OI), seems to be the most valuable tool in predicting pulmonary damage severity, though OI is not listed in either of the previous definitions. We support the recommended use of OI by 2015 consensus conference.

Venoarterial Extracorporeal Membrane Oxygenation for Severe Neonatal Acute Respiratory Distress Syndrome in a Developing Country

Objective: Extracorporeal membrane oxygenation (ECMO) has supported oxygen delivery and carbon dioxide removal in neonatal severe respiratory failure for more than 4 decades. The definition and diagnosis of neonatal acute respiratory distress syndrome (ARDS) was made according to the criteria first established by a Montreux Conference in 2017. By far, there has been no ECMO efficiency studies in neonatal ARDS. We aimed to compare the outcomes of neonates with severe ARDS supported with and without ECMO. Design: Retrospective pair-matched study. Setting: In the present retrospective pair-matched study, the outcomes of severe ARDS with ECMO support and without ECMO support were analyzed and compared. Propensity score matching was conducted. The study subjects were selected from a China Neonatal ECMO (CNECMO) study. In total, five hospitals were included in the CNECMO study. The patients were matched with demographic and clinical data. The primary endpoint was in-hospital mortality. Secondary outcomes included ventilator-time, ICU stay, hospitalization costs and cranial MRI results. Patients: 145 neonates with severe ARDS (Oxygenation Index, OI ≥16) from 5 hospitals. Interventions: No interventions. Measurements and Main Results: We collected the data of 145 neonates with severe ARDS (Oxygenation Index, OI≥16) from 5 hospitals. Among them, 42 neonates received venoarterial (VA) ECMO support, and the remaining 103 neonates were treated with conventional mechanical ventilation. The mortality of ECMO-supported neonates was not significantly different compared with the ESLO neonatal respiratory-supported from 2012 to 2018 (23.8 vs. 32.5%, p = 0.230). After matching with the propensity score we got 31 pairs. The ECMO-supported neonates had a lower in-hospital mortality (6 of 31, 19.4%) vs. non ECMO-supported patients (18 of 31, 58.1%) (p = 0.002). Hospitalization costs of survivors in ECMO-supported neonates were significantly higher than that of non-ECMO-supported neonates (p < 0.001). There was no difference of ventilator-times (p = 0.206), ICU stay (p = 0.879) and cranial MRI (p = 0.899) between the survivors of ECMO-supported and non-ECMO-supported neonates with ARDS. Conclusions: By far, there has been no ECMO efficiency studies in neonatal ARDS. This study found that ECMO-support have superior outcomes compared with non-ECMO-support in neonates with severe ARDS.

Lactate clearance for initiating and weaning off extracorporeal membrane oxygenation in a child with regressed left ventricle after arterial switch operation

We hereby report a child with transposition of great arteries and regressed ventricle who underwent arterial switch operation (ASO) with the aid of cardiopulmonary bypass and “integrated” extracorporeal membrane oxygenation (ECMO) circuit. The significance of lactate clearance as a guide to initiate and terminate veno-arterial ECMO in a post ASO child with regressed left ventricle is discussed.

Evaluation of the oxygenation index in adult respiratory failure

BACKGROUND

The oxygenation index (mean airway pressure × FIO2 divided by PaO2) was originally devised to measure severity of illness and predict outcome in neonatal respiratory failure. We evaluated the discrimination of a modified oxygenation index (modified with age) for predicting 28-day mortality in adults with respiratory failure (adult respiratory distress syndrome [ARDS]) using the ALVEOLI section of the ARDSNet database and validated the results in the full ARDSNet database.

METHODS

We compared age-adjusted oxygenation index (AOI) on ventilator Days 1 to 4 with 28-day mortality.

RESULTS

AOI correlated positively with mortality (area under the receiver operating characteristic curve, 0.70-0.74, for ARDS Days 1-4). Following initial development, AOI related to mortality was validated in two other ARDSNet databases producing similar results (area under the receiver operating characteristic curve, 0.70-0.78).

CONCLUSION

The observed sensitivity and specificity analysis demonstrated that AOI is equivalent to or better than other mortality prediction systems used for ARDS.

LEVEL OF EVIDENCE

Prognostic, level III.

High-frequency oscillatory ventilation in children with acute respiratory distress syndrome: experience of a pediatric intensive care unit

OBJECTIVE

To describe the effects of high-frequency oscillatory ventilation (HFOV) as a rescue ventilatory support in pediatric patients with acute respiratory distress syndrome (ARDS).

METHODS

Twenty-five children (1 month < age < 17 years) admitted to a university hospital pediatric intensive care unit (ICU) with ARDS and submitted to HFOV for a minimum of 48 hours after failure of conventional mechanical ventilation were assessed.

RESULTS

Twenty eight days after the onset of ARDS, the mortality rate was 52% (13/25). Over the course of 48 hours, the use of HFOV reduced the oxygenation index [38 (31-50) vs. 17 (10-27)] and increased the ratio of partial arterial pressure O2 and fraction of inspired O2 [65 [44-80) vs. 152 (106-213)]. Arterial CO2 partial pressure [54 (45-74) vs. 48 (39-58) mmHg] remained unchanged. The mean airway pressure ranged between 23 and 29 cmH2O. HFOV did not compromise hemodynamics, and a reduction in heart rate was observed (141±32 vs. 119±22 beats/min), whereas mean arterial pressure (66±20 vs. 71±17 mmHg) and inotropic score [44 (17-130) vs. 20 (16-75)] remained stable during this period. No survivors were dependent on oxygen.

CONCLUSION

HFOV improves oxygenation in pediatric patients with ARDS and severe hypoxemia refractory to conventional ventilatory support.

Acute respiratory failure

Acute respiratory failure is common in critically ill children, who are at increased risk of respiratory embarrassment because of the developmental variations in the respiratory system. Although multiple etiologies exist, pneumonia and bronchiolitis are most common. Respiratory system monitoring has evolved, with the clinical examination remaining paramount. Invasive tests are commonly replaced with noninvasive monitors. Children with ALI/ARDS have better overall outcomes than adults, although data regarding specific therapies are still lacking. Most children will have some degree of long-term physiologic respiratory compromise after recovery from ALI/ARDS. The physiologic basis for respiratory failure and its therapeutic options are reviewed here.

Using serial oxygenation index as an objective predictor of survival for antenatally diagnosed congenital diaphragmatic hernia

INTRODUCTION

Best oxygenation index on day 1 (BOId1) had been shown to predict survival in congenital diaphragmatic hernia (CDH). Serial oxygenation index (OI) may enable better assessment of response to cardiorespiratory support than BOId1.

METHODS

All antenatally diagnosed CDH from one tertiary neonatal unit were retrospectively reviewed. Oxygenation index at 6, 12, 24, and 48 hours from birth, as well as BOId1, were compared between survivors and nonsurvivors. The area under the curve and receiver operating characteristic (ROC) curves were used to compare serial OI within the first 24 hours and BOId1 between survivors and nonsurvivors. Statistical significance was set at P < .05.

RESULTS

Twenty-four patients with CDH (13 survivors, 11 nonsurvivors) were included. Both groups were comparable in demographics and variables that could affect outcome. In terms of nonsurvival, ROC curve analysis demonstrated a sensitivity of 78% for serial OI greater than 252 and 56% for BOId1 greater than 8.5, both having a specificity of 100%. The area under the ROC curve for serial OI and BOId1 were 0.96 and 0.85, respectively. The positive predictive value of serial OI (>252) and BOId1 (>11) for nonsurvival were both 100%, with an negative predictive value of 87% and 76%, respectively.

CONCLUSIONS

Our preliminary study showed that serial OI in the first 24 hours of life is a good predictor of survival. It is simple to use and has the added advantage of assessing response to medical support in CDH. The results support the need for a large prospective study exploring the potential of serial OI to guide management and prognosis.

Outcomes in children with refractory pneumonia supported with extracorporeal membrane oxygenation

PURPOSE

To review the use of extracorporeal membrane oxygenation (ECMO) in severe paediatric pneumonia and evaluate factors that may affect efficacy of this treatment.

METHODS

Retrospective study of the ECMO database of a tertiary paediatric intensive care unit and chart review of all patients who were managed with ECMO during their treatment for severe pneumonia over a 23-year period. The main outcome measures were survival to hospital discharge, and ICU and hospital length of stay. We compared the groups of culture-positive versus culture-negative pneumonia, venoarterial (VA) versus venovenous (VV) ECMO, community- versus hospital-acquired cases, and cases before and after 2005.

RESULTS

Fifty patients had 52 cases of pneumonia managed with ECMO. Community-acquired cases were sicker with higher oxygenation index (41.5 ± 20.5 versus 26.8 ± 17.8; p = 0.031) and higher inotrope score [20 (5-37.5) versus 7.5 (0-18.8); p = 0.07]. Use of VA compared with VV ECMO was associated with higher inotrope scores [20 (10-50) versus 5 (0-20); p = 0.012]. There was a trend towards improved survival in the VV ECMO group (82.4 versus 62.9 %; p = 0.15). Since 2005, patients have been older [4.7 (1-8) versus 1.25 (0.15-2.8) years; p = 0.008] and survival has improved (88.2 versus 60.0 %; p = 0.039).

CONCLUSIONS

Survival in children with pneumonia requiring ECMO has improved over time and is now 90 % in the modern era. Risk factors for death include performing a circuit change [odds ratio (OR) 5.0; 95 % confidence interval (CI) 1.02-24.41; p = 0.047] and use of continuous renal replacement therapy (OR 4.2; 95 % CI 1.13-15.59; p = 0.032).

Heart Failure Treated with Low-dose Milrinone in a Full-term Newborn

A term newborn with a hypocontractile myocardium complicating persistent pulmonary hypertension of the newborn was successfully treated with a low-dose phosphodiesterase III inhibitor milrinone. Echocardiography diagnosed heart failure with a left ventricular ejection fraction of 35% and a left ventricular shortening fraction of 18% and severe persistent pulmonary hypertension of the newborn with oxygenation index of 28. Milrinone was started at an initial dose of 50 mcg/kg, followed by continuous infusion of 0.20 mcg/kg/min. With lowdose milrinone oxygenation index decreased to 3 within 6 hours, left ventricular ejection fraction and left ventricular shortening fraction increased to 57%, and 30%, respectively. Low doses of milrinone might be promising in the treatment of heart failure and persistent pulmonary hypertension of the newborn in term newborns.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Severe hypoxemic respiratory failure: part 1--ventilatory strategies

Approximately 16% of deaths in patients with ARDS results from refractory hypoxemia, which is the inability to achieve adequate arterial oxygenation despite high levels of inspired oxygen or the development of barotrauma. A number of ventilator-focused rescue therapies that can be used when conventional mechanical ventilation does not achieve a specific target level of oxygenation are discussed. A literature search was conducted and narrative review written to summarize the use of high levels of positive end-expiratory pressure, recruitment maneuvers, airway pressure-release ventilation, and high-frequency ventilation. Each therapy reviewed has been reported to improve oxygenation in patients with ARDS. However, none of them have been shown to improve survival when studied in heterogeneous populations of patients with ARDS. Moreover, none of the therapies has been reported to be superior to another for the goal of improving oxygenation. The goal of improving oxygenation must always be balanced against the risk of further lung injury. The optimal time to initiate rescue therapies, if needed, is within 96 h of the onset of ARDS, a time when alveolar recruitment potential is the greatest. A variety of ventilatory approaches are available to improve oxygenation in the setting of refractory hypoxemia and ARDS. Which, if any, of these approaches should be used is often determined by the availability of equipment and clinician bias.

Predictors of outcome for children requiring respiratory extra-corporeal life support: implications for inclusion and exclusion criteria

OBJECTIVES

A range of children receive extra-corporeal life support (ECLS) for respiratory failure, but there is little published data on this group. Our aims were: (1) to analyse predictors of outcome and (2) comment on inclusion and exclusion criteria.

DESIGN

Retrospective review.

SETTING

Tertiary ECLS centre.

PATIENTS

A total of 124 children categorised as 'paediatric respiratory ECLS' from July 1992 to December 2005.

RESULTS

Fifty-three percent of children had one or more co-morbid conditions; the median age was 10.1 (IQR 3-34) months; the median ECLS duration was 9 (IQR 5-17) days; survival to discharge was 62% and at 1 year was 59%. Although survival varied according to primary reason for ECLS (range 36-100%), after adjustment for this, the presence of a co-morbid condition was unrelated to mortality (OR = 1.49, 95% CI 0.65, 3.42, P = 0.34) Predictors of mortality were increased pre-ECLS oxygenation index (OR = 1.09, 95% CI 1.00, 1.18, P = 0.05) and shock (OR 2.53, 95% CI 1.21, 5.28, P = 0.01). The relationship between mortality and end organ dysfunction (OR 2.12, 95% CI 0.89, 5.02, P = 0.09) and greater number of pre-ECLS ventilator days (OR 1.10, 95% CI 0.99, 1.22, P = 0.08) was less conclusive.

CONCLUSIONS

Pre-existing co-morbid conditions may predispose children to develop severe respiratory failure but with careful case selection, do not appear to reduce the chance of survival. Severity of pulmonary dysfunction determined by OI and shock were key predictors of outcome and should remain important determinants of referral for ECLS.

Predictors of mortality in acute lung injury during the era of lung protective ventilation

BACKGROUND

Lung protective ventilation has been widely adopted for the management of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Consequently, ventilator associated lung injury and mortality have decreased. It is not known if this ventilation strategy changes the prognostic value of previously identified demographic and pulmonary predictors of mortality, such as respiratory compliance and the arterial oxygen tension to inspired oxygen fraction ratio (Pao(2)/Fio(2)).

METHODS

Demographic, clinical, laboratory and pulmonary variables were recorded in 149 patients with ALI/ARDS. Significant predictors of mortality were identified in bivariate analysis and these were entered into multivariate analysis to identify independent predictors of mortality.

RESULTS

Hospital mortality was 41%. In the bivariate analysis, 17 variables were significantly correlated with mortality, including age, APACHE II score and the presence of cirrhosis. Pulmonary parameters associated with death included Pao(2)/Fio(2) and oxygenation index ((mean airway pressurexFio(2)x100)/Pao(2)). In unadjusted analysis, the odds ratio (OR) of death for Pao(2)/Fio(2) was 1.57 (CI 1.12 to 3.04) per standard deviation decrease. However, in adjusted analysis, Pao(2)/Fio(2) was not a statistically significant predictor of death, with an OR of 1.29 (CI 0.82 to 2.02). In contrast, oxygenation index (OI) was a statistically significant predictor of death in both unadjusted analysis (OR 1.89 (CI 1.28 to 2.78)) and in adjusted analysis (OR 1.84 (CI 1.13 to 2.99)).

CONCLUSIONS

In this cohort of patients with ALI/ARDS, OI was an independent predictor of mortality, whereas Pao(2)/Fio(2) was not. OI may be a superior predictor because it integrates both airway pressure and oxygenation into a single variable.