The Italian ECMO network experience during the 2009 influenza A(H1N1) pandemic: preparation for severe respiratory emergency outbreaks

Purpose

In view of the expected 2009 influenza A(H1N1) pandemic, the Italian Health Authorities set up a national referral network of selected intensive care units (ICU) able to provide advanced respiratory care up to extracorporeal membrane oxygenation (ECMO) for patients with acute respiratory distress syndrome (ARDS). We describe the organization and results of the network, known as ECMOnet.

Methods

The network consisted of 14 ICUs with ECMO capability and a national call center. The network was set up to centralize all severe patients to the ECMOnet centers assuring safe transfer. An ad hoc committee defined criteria for both patient transfer and ECMO institutions.

Results

Between August 2009 and March 2010, 153 critically ill patients (53% referred from other hospitals) were admitted to the ECMOnet ICU with suspected H1N1. Sixty patients (48 of the referred patients, 49 with confirmed H1N1 diagnosis) received ECMO according to ECMOnet criteria. All referred patients were successfully transferred to the ECMOnet centers; 28 were transferred while on ECMO. Survival to hospital discharge in patients receiving ECMO was 68%. Survival of patients receiving ECMO within 7?days from the onset of mechanical ventilation was 77%. The length of mechanical ventilation prior to ECMO was an independent predictor of mortality.

Conclusions

A network organization based on preemptive patient centralization allowed a high survival rate and provided effective and safe referral of patients with severe H1N1-suspected ARDS.     

Extracorporeal membrane oxygenation for severe influenza A (H1N1) acute respiratory distress syndrome: a prospective observational comparative study

Purpose

To compare characteristics, clinical evolution and outcome in adult patients with influenza A (H1N1) acute respiratory distress syndrome (ARDS) treated with or without extracorporeal membrane oxygenation (ECMO).

Methods

A prospective observational study of patients treated in Marseille South Hospital from October 2009 to January 2010 for confirmed influenza A (H1N1)-related ARDS. Clinical features, pulmonary dysfunction and mortality were compared between patients treated with and without ECMO.

Results

Of 18 patients admitted, 6 were treated with veno-venous and 3 with veno-arterial ECMO after median (interquartile, IQR) duration of mechanical ventilation of 10 (6–96) h. Six ECMO were initiated in a referral hospital by a mobile team, a median (IQR) of 3 (2–4) h after phone contact. Before ECMO, patients had severe respiratory failure with median (IQR) PaO₂ to FiO₂ ratio of 52 (50–60) mmHg and PaCO₂ of 85 (69–91) mmHg. Patients treated with or without ECMO had the same hospital mortality rate (56%, 5/9). Duration of ECMO therapy was 9 (4–14) days in survivors and 5 (2–25) days in non-survivors. Early improvement of PaO₂ to FiO₂ ratio was greater in ECMO survivors than non-survivors after ECMO initiation [295 (151–439) versus 131 (106–144) mmHg, p < 0.05]. Haemorrhagic complications occurred in four patients under ECMO, but none required surgical treatment.

Conclusions

ECMO may be an effective salvage treatment for patients with influenza A (H1N1)-related ARDS presenting rapid refractory respiratory failure, particularly when provided by a mobile team allowing early cannulation prior to transfer to a reference centre.     

Outcome of acute respiratory distress syndrome patients treated with extracorporeal membrane oxygenation and brought to a referral center

Purpose

Patients with severe acute respiratory distress syndrome (ARDS) are candidates for extracorporeal membrane oxygenation (ECMO) therapy. The evaluation of organ severity is difficult in patients considered for cannulation in a distant hospital. This study was designed to identify early factors associated with hospital mortality in ARDS patients treated with ECMO and retrieved from referring hospitals.

Methods

Data from 85 consecutive ARDS patients equipped with ECMO by our mobile team and consequently admitted to our ICU were prospectively collected and analyzed.

Results

The main ARDS etiologies were community-acquired bacterial pneumonia (35 %), influenza pneumonia (23 %) (with 12 patients having been treated during the first half of the study period), and nosocomial pneumonia (14 %). The median (interquartile range) time between contact from the referring hospital and patient cannulation was 3 (1–4) h. ECMO was venovenous in 77 (91 %) patients. No complications occurred during transport by our mobile unit. Forty-eight patients died at the hospital (56 %). Based on a multivariate logistic regression, a score including age, SOFA score, and a diagnosis of influenza pneumonia was constructed. The probability of hospital mortality following ECMO initiation was 40 % in the 0–2 score class (n = 58) and 93 % in the 3–4 score class (n = 27). Patients with an influenza pneumonia diagnosis and a SOFA score before ECMO of less than 12 had a mortality rate of 22 %.

Conclusions

Age, SOFA score, and a diagnosis of influenza may be used to accurately evaluate the risk of death in ARDS patients considered for retrieval under ECMO from distant hospitals.     

The use of the Berlin definition for acute respiratory distress syndrome during infancy and early childhood: multicenter evaluation and expert consensus

Purpose

A new acute respiratory distress syndrome (ARDS) definition has been recently issued: the so-called Berlin definition (BD) has some characteristics that could make it suitable for pediatrics. The European Society for Pediatric Neonatal Intensive Care (ESPNIC) Respiratory Section started a project to evaluate BD validity in early childhood. A secondary aim was reaching a consensus on clinical tools (risk factors list and illustrative radiographs) to help the application of BD.

Methods

This was an international, multicenter, retrospective study enrolling 221 children [aged greater than 30 days and less than 18 months; median age 6 (range 2–13) months], admitted to seven European pediatric intensive care units (PICU) with acute lung injury (ALI) or ARDS diagnosed with the earlier definition.

Results

Patients were categorized according to the two definitions, as follows: ALI, 36; ARDS, 185 (for the American–European Consensus Conference (AECC) definition); mild, 36; moderate, 97; severe ARDS, 88 (for BD). Mortality (13.9 % for mild ARDS; 11.3 % for moderate ARDS; 25 % for severe ARDS, p = 0.04) and the composite outcome extracorporeal membrane oxygenation (ECMO)/mortality (13.9 % for mild ARDS; 11.3 % for moderate ARDS; 28.4 % for severe ARDS, p < 0.01) were different across the BD classes, whereas they were similar using the previous definition. Mortality [HR 2.7 (95 % CI 1.1–7.1)] and ECMO/mortality [HR 3 (95 % CI 1.1–7.9)] were increased only for the severe ARDS class and remained significant after adjustment for confounding factors. PICU stay was not different across severity classes, irrespective of the definition used. There was significant concordance between raters evaluating radiographs [ICC 0.6 (95 % CI 0.2–0.8)] and risk factors [ICC 0.92 (95 % CI 0.8–0.97)].

Conclusions

BD validity for children is similar to that already reported in adults and mainly due to the introduction of a “severe ARDS” category. We provided clinical tools to use BD for clinical practice, research, and health services planning in pediatric critical care.     

Long-term mortality in patients with chronic obstructive pulmonary disease following extracorporeal membrane oxygenation for cardiac assist after cardiovascular surgery

Purpose

Information on predisposing risk factors influencing long-term survival after extracorporeal membrane oxygenation (ECMO) support remains scarce. In critically ill patients chronic obstructive pulmonary disease (COPD) is an independent risk factor for mortality and morbidity. We assessed the influence of COPD on cardiovascular and all-cause mortality in patients undergoing ECMO therapy.

Methods

We prospectively included 191 patients undergoing veno-arterial ECMO therapy following cardiovascular surgery at a university-affiliated tertiary care center into our registry.

Results

The median follow-up time was 51 months (IQR 34–71 months) corresponding to 4,197 overall months of follow-up. A total of 125 patients (65 %) died; 88 % of deaths were due to cardiovascular causes. Long-term survival was decreased in patients with COPD after 1 year (23 % vs. 44 %) and after 6 years (14 % vs. 35 %) compared to patients without COPD. COPD was independently associated with all-cause mortality with a hazard ratio of 4.22 (95 % CI 1.04–17.11, p = 0.04) and cardiovascular mortality with a hazard ratio of 5.87 (95 % CI 1.41–24.47, p = 0.02).

Conclusions

We identified COPD as a strong and independent predictor of long-term all-cause mortality and cardiovascular mortality in patients undergoing ECMO therapy following cardiovascular surgery. The current study presents valuable information for a comprehensive decision-making process prior to ECMO implantation and helps to identify high-risk patients that may benefit from intensified treatment of co-morbidities and close check-ups after hospital discharge.     

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

Purpose

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

Methods

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

Results

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

Conclusions

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

The PRESERVE mortality risk score and analysis of long-term outcomes after extracorporeal membrane oxygenation for severe acute respiratory distress syndrome

Purpose

This study was designed to identify factors associated with death by 6 months post-intensive care unit (ICU) discharge and to develop a practical mortality risk score for extracorporeal membrane oxygenation (ECMO)-treated acute respiratory distress syndrome (ARDS) patients. We also assessed long-term survivors’ health-related quality of life (HRQL), respiratory symptoms, and anxiety, depression and post-traumatic stress disorder (PTSD) frequencies.

Methods

Data from 140 ECMO-treated ARDS patients admitted to three French ICUs (2008–2012) were analyzed. ICU survivors contacted >6 months post-ICU discharge were assessed for HRQL, psychological and PTSD status.

Results

Main ARDS etiologies were bacterial (45 %), influenza A[H₁N₁] (26 %) and post-operative (17 %) pneumonias. Six months post-ICU discharge, 84 (60 %) patients were still alive. Based on multivariable logistic regression analysis, the PRESERVE (PRedicting dEath for SEvere ARDS on VV-ECMO) score (0–14 points) was constructed with eight pre-ECMO parameters, i.e. age, body mass index, immunocompromised status, prone positioning, days of mechanical ventilation, sepsis-related organ failure assessment, plateau pressure andpositive end-expiratory pressure. Six-month post-ECMO initiation cumulative probabilities of survival were 97, 79, 54 and 16 % for PRESERVE classes 0–2, 3–4, 5–6 and ≥7 (p < 0.001), respectively. HRQL evaluation in 80 % of the 6-month survivors revealed satisfactory mental health but persistent physical and emotional-related difficulties, with anxiety, depression or PTSD symptoms reported, by 34, 25 or 16 %, respectively.

Conclusions

The PRESERVE score might help ICU physicians select appropriate candidates for ECMO among severe ARDS patients. Future studies should also focus on physical and psychosocial rehabilitation that could lead to improved HRQL in this population.     

Associations between ventilator settings during extracorporeal membrane oxygenation for refractory hypoxemia and outcome in patients with acute respiratory distress syndrome: a pooled individual patient data analysis

Purpose

Extracorporeal membrane oxygenation (ECMO) is a rescue therapy for patients with acute respiratory distress syndrome (ARDS). The aim of this study was to evaluate associations between ventilatory settings during ECMO for refractory hypoxemia and outcome in ARDS patients.

Methods

In this individual patient data meta-analysis of observational studies in adult ARDS patients receiving ECMO for refractory hypoxemia, a time-dependent frailty model was used to determine which ventilator settings in the first 3 days of ECMO had an independent association with in-hospital mortality.

Results

Nine studies including 545 patients were included. Initiation of ECMO was accompanied by significant decreases in tidal volume size, positive end-expiratory pressure (PEEP), plateau pressure, and driving pressure (plateau pressure ? PEEP) levels, and respiratory rate and minute ventilation, and resulted in higher PaO₂/FiO₂, higher arterial pH and lower PaCO₂ levels. Higher age, male gender and lower body mass index were independently associated with mortality. Driving pressure was the only ventilatory parameter during ECMO that showed an independent association with in-hospital mortality [adjusted HR, 1.06 (95 % CI, 1.03–1.10)].

Conclusion

In this series of ARDS patients receiving ECMO for refractory hypoxemia, driving pressure during ECMO was the only ventilator setting that showed an independent association with in-hospital mortality.

     

Portable miniaturized extracorporeal membrane oxygenation systems for H1N1-related severe acute respiratory distress syndrome: A case series

Background

Technological advances improved the practice of “modern” extracorporeal membrane oxygenation (ECMO). In the present report, we describe the experience of a referral ECMO center using portable miniaturized ECMO systems for H1N1-related severe acute respiratory distress syndrome (ARDS).

Methods

An observational study of all patients with H1N1-associated ARDS treated with ECMO in Hospital S. João (Porto, Portugal) between November 2009 and April 2011 was performed. Extracorporeal membrane oxygenation support was established using either ELS or Cardiohelp systems (Maquet-Cardiopulmonary-AG, Hirrlingen, Germany).

Results

Ten adult patients with severe ARDS secondary to H1N1 infection (Pao₂/fraction of inspired oxygen, 69 mm Hg [56-84]; Murray score, 3.5 [3.5-3.8]) were included, and 60% survived to hospital discharge. Five patients were uneventfully transferred on ECMO from referring hospitals to our center by ambulance. Six patients were treated during the first postpandemic influenza season. All patients were treated with oseltamivir, and 1 received in addition zanamivir. Four patients received corticosteroids. Nosocomial infection was the most common complication (40%). Of the 4 deaths, 2 were caused by hemorrhagic shock; 1, by irreversible multiple organ failure; and 1, by refractory septic shock.

Conclusion

In our experience, ECMO support was a valuable therapeutic option for H1N1-related severe ARDS. The use of portable miniaturized systems allowed urgent rescue of patients from referring hospitals and safe interhospital and intrahospital transport during ECMO support.     

ECMO criteria for influenza A (H1N1)-associated ARDS: role of transpulmonary pressure

Purpose

To assess whether partitioning the elastance of the respiratory system (E _RS) between lung (E _L) and chest wall (E _CW) elastance in order to target values of end-inspiratory transpulmonary pressure (PPLAT_L) close to its upper physiological limit (25?cmH₂O) may optimize oxygenation allowing conventional treatment in patients with influenza A (H1N1)-associated ARDS referred for extracorporeal membrane oxygenation (ECMO).

Methods

Prospective data collection of patients with influenza A (H1N1)-associated ARDS referred for ECMO (October 2009?CJanuary 2010). Esophageal pressure was used to (a) partition respiratory mechanics between lung and chest wall, (b) titrate positive end-expiratory pressure (PEEP) to target the upper physiological limit of PPLAT_L (25?cmH₂O).

Results

Fourteen patients were referred for ECMO. In seven patients PPLAT_L was 27.2?±?1.2?cmH₂O; all these patients underwent ECMO. In the other seven patients, PPLAT_L was 16.6?±?2.9?cmH₂O. Raising PEEP (from 17.9?±?1.2 to 22.3?±?1.4?cmH₂O, P?=?0.0001) to approach the upper physiological limit of transpulmonary pressure (PPLAT_L?=?25.3?±?1.7?cm H₂O) improved oxygenation index (from 37.4?±?3.7 to 16.5?±?1.4, P?=?0.0001) allowing patients to be treated with conventional ventilation.

Conclusions

Abnormalities of chest wall mechanics may be present in some patients with influenza A (H1N1)-associated ARDS. These abnormalities may not be inferred from measurements of end-inspiratory plateau pressure of the respiratory system (PPLAT_RS). In these patients, titrating PEEP to PPLAT_RS may overestimate the incidence of hypoxemia refractory to conventional ventilation leading to inappropriate use of ECMO.     

Impact of fluid balance on outcome of adult patients treated with extracorporeal membrane oxygenation

Purpose

To assess the relationship between early daily fluid balance (FB) and 90-day outcome in adult patients treated with extracorporeal membrane oxygenation (ECMO).

Design

Retrospective observational study.

Setting

Tertiary referral centre for ECMO.

Patients

115 patients treated with ECMO for refractory heart failure and 57 patients treated with ECMO for refractory respiratory failure.

Methods

We analysed the association between early daily FB versus hospital and 90-day mortality using multivariable logistic regression model, Cox proportional-hazards model and propensity score.

Results

We obtained detailed demographic, clinical, and biochemical data, daily FB, and continuous renal replacement days. Fifty-seven per cent of patients had acute kidney injury (AKI) at ECMO initiation, and 60 % (n = 103) of patients received continuous renal replacement therapy (CRRT) during ECMO course, beginning at a median of 1 (0–3.5) days after ECMO initiation. Overall 90-day mortality was 24 %. Survivors exhibited lower daily FB from day 3 to day 5. After adjustments, Acute Physiology and Chronic Health Evaluation (APACHE) III, CRRT during the first 3 days, major bleeding event at day 1 and positive FB on day 3 were independent predictors of 90-day mortality. Positive FB at ECMO day 3 remained an independent predictor of hospital and 90-day mortality, regardless of the statistical model used or the inclusion of a propensity score to have positive FB.

Conclusions

Positive FB at ECMO day 3 is an independent predictor of 90-day mortality. Further interventional studies aimed at testing the value of strategy of tight control of FB during the early ECMO period are now warranted.     

Virus-associated hemophagocytic syndrome as a major contributor to death in patients with 2009 influenza A (H1N1) infection

Introduction

Virus-associated hemophagocytic syndrome (VAHS) is a severe complication of various viral infections often resulting in multiorgan failure and death. The purpose of this study was to describe baseline characteristics, development of VAHS, related treatments and associated mortality rate of consecutive critically ill patients with confirmed 2009 influenza A (H1N1) infection and respiratory failure.

Methods

We conducted a prospective observational study of 25 critically ill patients with 2009 influenza A (H1N1) infection at a single-center intensive care unit in Germany between 5 October 2009 and 4 January 2010. Demographic data, comorbidities, diagnosis of VAHS, illness progression, treatments and survival data were collected. The primary outcome measure was the development of VAHS and related mortality. Secondary outcome variables included duration of mechanical ventilation, support of extracorporeal membrane oxygenation and duration of viral shedding.

Results

VAHS developed in 9 (36%) of 25 critically ill patients with confirmed 2009 influenza A (H1N1) infection, and 8 (89%) of them died. In contrast, the mortality rate in the remaining 16 patients without VAHS was 25% (P = 0.004 for the survival difference in patients with or without VAHS by log-rank analysis). The patients were relatively young (median age, 45 years; interquartile range (IQR), 35 to 56 years of age); however, 18 patients (72%) presented with one or more risk factors for a severe course of illness. All 25 patients received mechanical ventilation for severe acute respiratory distress syndrome and refractory hypoxemia, with a median duration of mechanical ventilation of 19 days (IQR, 13 to 26 days). An additional 17 patients (68%) required extracorporeal membrane oxygenation for a median of 10 days (IQR, 6 to 19 days).

Conclusions

The findings of this study raise the possibility that VAHS may be a frequent complication of severe 2009 influenza A (H1N1) infection and represents an important contributor to multiorgan failure and death.     

Blood oxygenation and decarboxylation determinants during venovenous ECMO for respiratory failure in adults

Purpose

This study was designed to optimize the latest generation venovenous (vv)-extracorporeal membrane oxygenation (ECMO)-circuit configuration and settings based on the evaluation of blood oxygenation and CO₂ removal determinants in patients with severe acute respiratory distress syndrome (ARDS) on ultraprotective mechanical ventilation.

Methods

Blood gases and hemodynamic parameters were evaluated after changing one of three ECMO settings, namely, circuit blood flow, FiO_2ECMO (fraction of inspired oxygen in circuit), or sweep gas flow ventilating the membrane, while leaving the other two parameters at their maximum setting.

Results

Ten mechanically ventilated ARDS patients (mean age 44 ± 16 years; 6 males; mean hemoglobin 8.0 ± 1.8 g/dL) on ECMO for a mean of 9.0 ± 3.8 days) receiving femoro–jugular vv-ECMO were evaluated. vv-ECMO blood flow and FiO_2ECMO determined arterial oxygenation. Decreasing the ECMO flow from its baseline maximum value (5.8 ± 0.8 L/min) to 40 % less (2.4 ± 0.3 L/min) significantly decreased mean PaO₂ (arterial oxygen tension; 88 ± 24 to 45 ± 9 mm Hg; p < 0.001) and SaO₂ (oxygen saturation; 97 ± 2 to 82 ± 10 %; p < 0.001). When the ECMO flow/cardiac output was >60 %, SaO₂ was always >90 %. Alternatively, the rate of sweep gas flow through the membrane lung determined blood decarboxylation, while PaCO₂ (arterial carbon dioxide tension) was unaffected when the ECMO blood flow and FiO_2ECMO were reduced to <2.5 L/min and 40 %, respectively. In three additional patients evaluated before and after red blood cell transfusion, O₂ delivery increased after transfusion, allowing lower ECMO flows to reach adequate SaO₂.

Conclusions

For severe ARDS patients receiving femoro–jugular vv-ECMO, blood flow was the main determinant of arterial oxygenation, while CO₂ elimination depended on sweep gas flow through the oxygenator. An ECMO flow/cardiac output >60 % was constantly associated with adequate blood oxygenation and oxygen transport and delivery.     

Nutrition support during extracorporeal membrane oxygenation (ECMO) in adults: a retrospective audit of 86 patients

Purpose

Extracorporeal membrane oxygenation (ECMO) is increasingly being used to support critically ill patients with severe cardiac and/or respiratory failure. It has been claimed that the resulting haemodynamic alterations, particularly in venoarterial ECMO, mean that enteral feeding is unsafe and/or poorly tolerated. This study aims to investigate this question and to identify any barriers to optimal nutrition.

Methods

Data were retrospectively collected for 86 patients who received ECMO between January 2007 and July 2012 in a tertiary critical care unit/ECMO referral centre. All were fed using existing protocols that emphasise early enteral feeding in preference over parenteral or delayed enteral nutrition.

Results

Thirty-one patients required ECMO for cardiac failure, and all of these received venoarterial ECMO; the remainder received venovenous ECMO. Enteral feeds started for all patients at average 13.1 h [standard deviation (SD) 16.7 h] after ICU admission, reaching goal rate on day 2.6 (SD 1.4). Thirty-three patients experienced significant feeding intolerance during the first 5 days, but of these 20 were managed effectively with prokinetic medications; 18 required parenteral nutrition to supplement inadequately tolerated tube feeds. Intolerance did not differ between ECMO modes. Overall patients tolerated 79.7 % of goal nutrition each day in the first 2 weeks.

Conclusions

Enteral feeding can be well tolerated by patients who are receiving ECMO, whether in venovenous or venoarterial mode. ECMO should not exclude patients from receiving the well-documented benefits of early enteral feeding in critical illness.     

Critically ill infants and children with influenza A (H1N1) in pediatric intensive care units in Argentina

Objective

To determine the epidemiological features, course, and outcomes of critically ill pediatric patients with Influenza A (H1N1) virus.

Design

Prospective cohort of children in pediatric intensive care units (PICUs) due to Influenza A (H1N1) virus infection.

Setting

Seventeen medical-surgical PICUs in tertiary care hospital in Argentina.

Patients

All consecutive patients admitted to the PICUs with influenza A (H1N1) viral infection from 15 June to 31 July 2009.

Measurements and main results

Of 437 patients with acute lower respiratory infection in PICUs, 147 (34%) were diagnosed with influenza A (H1N1) related to critical illness. The median age of these patients was 10 months (IQR 3–59). Invasive mechanical ventilation was used in 117 (84%) on admission. The rate of acute respiratory distress syndrome (ARDS) was 80% (118 of 147 patients). Initial non-invasive ventilation failed in 19 of 22 attempts (86%). Mortality at 28 days was 39% (n = 57). Chronic complex conditions (CCCs), acute renal dysfunction (ARD) and ratio PaO₂/FiO₂ at day 3 on MV were independently associated with a higher risk of mortality. The odds ratio (OR) for CCCs was 3.06, (CI 95% 1.36–6.84); OR for ARD, 3.38, (CI 95% 1.45–10.33); OR for PaO₂/FiO₂, 4 (CI 95% 1.57–9.59). The administration of oseltamivir within 24 h after admission had a protective effect: OR 0.2 (CI 95% 0.07–0.54).

Conclusions

In children with ARDS, H1N1 as an etiologic agent confers high mortality, and the presence of CCCs in such patients increases the risk of death.     

Retrieval of critically ill adults using extracorporeal membrane oxygenation: an Australian experience

Purpose

A retrieval program was developed in New South Wales (NSW), Australia to provide extracorporeal membrane oxygenation support (ECMO) for the safe transport of adults with severe, acute respiratory or cardiac failure. We describe the development and results of this program and the impact of the 2009 H1N1 epidemic on this service.

Methods

An observational study of all patients who were retrieved on ECMO support in NSW, from March 1, 2007 to June 1, 2010, was carried out.

Results

Forty adult patients were retrieved on ECMO support (median age 34?years). The indications for retrieval were respiratory in 38 patients (of whom 16 were confirmed or suspected H1N1 cases) and cardiac in 2 patients. Two other patients died after referral but before ECMO support could be established. Patients were transported by road (n?=?26, 65%), medical retrieval jet (n?=?10, 25%) and helicopter (n?=?4, 10%). The median retrieval distance was 250?km (range 12?C1,960?km). Thirty-four patients (85%) survived to hospital discharge. Survival for respiratory indications was 87% (33/38 patients) and 50% (1/2 patients) for cardiac indications. There were no deaths or major morbidity associated with these retrievals.

Conclusions

Patients with very severe respiratory failure, which was considered to preclude conventional ventilation for safe transfer to tertiary centres, were managed by an ECMO referral and retrieval program in NSW and had a high rate of survival. This program also enhanced the capacity of the state to respond to a surge in demand for ECMO support due to the H1N1 epidemic, although the role of ECMO in respiratory failure is not yet well defined.     

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).     

Opening pressures and atelectrauma in acute respiratory distress syndrome

Purpose

Open lung strategy during ARDS aims to decrease the ventilator-induced lung injury by minimizing the atelectrauma and stress/strain maldistribution. We aim to assess how much of the lung is opened and kept open within the limits of mechanical ventilation considered safe (i.e., plateau pressure 30 cmH₂O, PEEP 15 cmH₂O).

Methods

Prospective study from two university hospitals. Thirty-three ARDS patients (5 mild, 10 moderate, 9 severe without extracorporeal support, ECMO, and 9 severe with it) underwent two low-dose end-expiratory CT scans at PEEP 5 and 15 cmH₂O and four end-inspiratory CT scans (from 19 to 40 cmH₂O). Recruitment was defined as the fraction of lung tissue which regained inflation. The atelectrauma was estimated as the difference between the intratidal tissue collapse at 5 and 15 cmH₂O PEEP. Lung ventilation inhomogeneities were estimated as the ratio of inflation between neighboring lung units.

Results

The lung tissue which is opened between 30 and 45 cmH₂O (i.e., always closed at plateau 30 cmH₂O) was 10 ± 29, 54 ± 86, 162 ± 92, and 185 ± 134 g in mild, moderate, and severe ARDS without and with ECMO, respectively (p < 0.05 mild versus severe without or with ECMO). The intratidal collapses were similar at PEEP 5 and 15 cmH₂O (63 ± 26 vs 39 ± 32 g in mild ARDS, p = 0.23; 92 ± 53 vs 78 ± 142 g in moderate ARDS, p = 0.76; 110 ± 91 vs 89 ± 93, p = 0.57 in severe ARDS without ECMO; 135 ± 100 vs 104 ± 80, p = 0.32 in severe ARDS with ECMO). Increasing the applied airway pressure up to 45 cmH₂O decreased the lung inhomogeneity slightly (but significantly) in mild and moderate ARDS, but not in severe ARDS.

Conclusions

Data show that the prerequisites of the open lung strategy are not satisfied using PEEP up to 15 cmH₂O and plateau pressure up to 30 cmH₂O. For an effective open lung strategy, higher pressures are required. Therefore, risks of atelectrauma must be weighted versus risks of volutrauma.

Trial registration

Clinicaltrials.gov identifier: NCT01670747 (www.clinicaltrials.gov).

     

Predicting mortality risk in patients undergoing venovenous ECMO for ARDS due to influenza A (H1N1) pneumonia: the ECMOnet score

Purpose

The decision to start venovenous extracorporeal membrane oxygenation (VV ECMO) is commonly based on the severity of respiratory failure, with little consideration of the extrapulmonary organ function. The aim of the study was to identify predictors of mortality and to develop a score allowing a better stratification of patients at the time of VV ECMO initiation.

Methods

This was a prospective multicenter cohort study on 60 patients with influenza A (H1N1)-associated respiratory distress syndrome participating in the Italian ECMOnet data set in the 2009 pandemic. Criteria for ECMO institution were standardized according to national guidelines.

Results

The survival rate in patients treated with ECMO was 68 %. Significant predictors of death before ECMO institution by multivariate analysis were hospital length of stay before ECMO institution (OR = 1.52, 95 % CI 1.12–2.07, p = 0.008); bilirubin (OR = 2.32, 95 % CI 1.52–3.52, p < 0.001), creatinine (OR = 7.38, 95 % CI 1.43–38.11, p = 0.02) and hematocrit values (OR = 0.82, 95 % CI 0.72–0.94, p = 0.006); and mean arterial pressure (OR = 0.92, 95 % CI 0.88–0.97, p < 0.001). The ECMOnet score was developed based on these variables, with a score of 4.5 being the most appropriate cutoff for mortality risk prediction. The high accuracy of the ECMOnet score was further confirmed by ROC analysis (c = 0.857, 95 % CI 0.754–0.959, p < 0.001) and by an independent external validation analysis (c = 0.694, 95 % CI 0.562–0.826, p = 0.004).

Conclusions

Mortality risk for patients receiving VV ECMO is correlated to the extrapulmonary organ function at the time of ECMO initiation. The ECMOnet score is a tool for the evaluation of the appropriateness and timing of VV ECMO in acute lung failure.     

Neurologic complications in neonates supported with extracorporeal membrane oxygenation. An analysis of ELSO registry data

Background

Neurologic complications in neonates supported with extracorporeal membrane oxygenation (ECMO) are common and diminish their quality of life and survival. An understanding of factors associated with neurologic complications in neonatal ECMO is lacking. The goals of this study were to describe the epidemiology and factors associated with neurologic complications in neonatal ECMO.

Patients and methods

Retrospective cohort study of neonates (age ≤30 days) supported with ECMO using data reported to the Extracorporeal Life Support Organization during 2005–2010.

Results

Of 7,190 neonates supported with ECMO, 1,412 (20 %) had neurologic complications. Birth weight <3 kg [odds ratio (OR): 1.3; 95 % confidence intervals (CI): 1.1–1.5], gestational age (<34 weeks; OR 1.5, 95 % CI 1.1–2.0 and 34–36 weeks: OR 1.4, 95 % CI 1.1–1.7), need for cardiopulmonary resuscitation prior to ECMO (OR 1.7, 95 % CI 1.5–2.0), pre-ECMO blood pH ≤ 7.11 (OR 1.7, 95 % CI 1.4–2.1), pre-ECMO bicarbonate use (OR 1.3, 95 % CI 1.2–1.5), prior ECMO exposure (OR 2.4, 95 % CI 1.6–2.6), and use of veno-arterial ECMO (OR 1.7, 95 % CI 1.4–2.0) increased neurologic complications. Mortality was higher in patients with neurologic complications compared to those without (62 % vs. 36 %; p < 0.001).

Conclusions

Neurologic complications are common in neonatal ECMO and are associated with increased mortality. Patient factors, pre-ECMO severity of illness, and use of veno-arterial ECMO are associated with increased neurologic complications. Patient selection, early ECMO deployment, and refining ECMO management strategies for vulnerable populations could be targeted as areas for improvement in neonatal ECMO.