A systematic review to inform institutional decisions about the use of extracorporeal membrane oxygenation during the H1N1 influenza pandemic

Extracorporeal membrane oxygenation technology for adults: an evidence mapping based on systematic reviews

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is a cutting-edge life-support measure for patients with severe cardiac and pulmonary illnesses. Although there are several systematic reviews (SRs) about ECMO, it remains to be seen how quality they are and how efficacy and safe the information about ECMO they describe is in these SRs. Therefore, performing an overview of available SRs concerning ECMO is crucial.

METHODS

We searched four electronic databases from inception to January 2023 to identify SRs with or without meta-analyses. The Assessment of Multiple Systematic Reviews 2 (AMSTAR-2) tool, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system were used to assess the methodological quality, and evidence quality for SRs, respectively. A bubble plot was used to visually display clinical topics, literature size, number of SRs, evidence quality, and an overall estimate of efficacy.

RESULTS

A total of 17 SRs met eligibility criteria, which were combined into 9 different clinical topics. The methodological quality of the included SRs in this mapping was "Critically low" to "Moderate". One of the SRs was high-quality evidence, three on moderate, three on low, and two on very low-quality evidence. The most prevalent study used to evaluate ECMO technology was observational or cohort study with frequently small sample sizes. ECMO has been proven beneficial for severe ARDS and ALI due to the H1N1 influenza infection. For ARDS, ALF or ACLF, and cardiac arrest were concluded to be probably beneficial. For dependent ARDS, ARF, ARF due to the H1N1 influenza pandemic, and cardiac arrest of cardiac origin came to an inconclusive conclusion. There was no evidence for a harmful association between ECMO and the range of clinical topics.

CONCLUSIONS

There is limited available evidence for ECMO that large sample, multi-center, and multinational RCTs are needed. Most clinical topics are reported as beneficial or probably beneficial of SRs for ECMO. Evidence mapping is a valuable and reliable methodology to identify and present the existing evidence about therapeutic interventions.

ECMO use in COVID-19: lessons from past respiratory virus outbreaks-a narrative review

The spread of coronavirus disease 2019 (COVID-19) continues to grow exponentially in most countries, posing an unprecedented burden on the healthcare sector and the world economy. Previous respiratory virus outbreaks, such as severe acute respiratory syndrome (SARS), pandemic H1N1 and Middle East respiratory syndrome (MERS), have provided significant insights into preparation and provision of intensive care support including extracorporeal membrane oxygenation (ECMO). Many patients have already been supported with ECMO during the current COVID-19 pandemic, and it is likely that many more may receive ECMO support, although, at this point, the role of ECMO in COVID-19-related cardiopulmonary failure is unclear. Here, we review the experience with the use of ECMO in the past respiratory virus outbreaks and discuss potential role for ECMO in COVID-19.

Supportive care for patient with respiratory diseases: an umbrella review

Background

Supportive treatment is an important and effective part of the management for patients with life-threatening diseases. This study aims to identify and evaluate the forms of supportive care for patients with respiratory diseases.

Methods

An umbrella review of supportive care for patient with respiratory diseases was undertaken. We comprehensively searched the following databases: Medline, EMBASE, Web of Science, CNKI (China National Knowledge Infrastructure), Wanfang Data and CBM (SinoMed) from their inception to 31 March 2020, and other sources to identify systematic reviews and meta-analyses related to supportive treatments for patient with respiratory diseases including Coronavirus Disease 2019 (COVID-19), severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS) and influenza. We assessed the methodological quality using the AMSTAR score and the quality of the evidence for the primary outcomes of each included systematic review and meta-analysis.

Results

We included 18 systematic reviews and meta-analyses in this study. Most studies focused on the respiratory and circulatory support. Ten studies were of high methodological quality, five studies of medium quality, and three studies of low quality. According to four studies extracorporeal membrane oxygenation did not reduce mortality in adults [odds ratio/relative risk (OR/RR) ranging from 0.71 to 1.28], but two studies reported significantly lower mortality in patients receiving venovenous extracorporeal membrane oxygenation than in the control group (OR/RR ranging from 0.38 to 0.73). Besides, monitoring of vital signs and increasing the number of medical staff may also reduce the mortality in patients with respiratory diseases.

Conclusions

Our overview suggests that supportive care may reduce the mortality of patients with respiratory diseases to some extent. However, the quality of evidence for the primary outcomes in the included studies was low to moderate. Further systematic reviews and meta-analyses are needed to address the evidence gap regarding the supportive care for SARS, MERS and COVID-19.

Retrieval of critically ill adults using extracorporeal membrane oxygenation: the nine-year experience in New South Wales

In New South Wales, a coordinated extracorporeal membrane oxygenation (ECMO) retrieval program has been in operation since 2007. This study describes the characteristics and outcomes of patients transported by this service. We performed a retrospective observational study and included patients who were transported on ECMO to either of two adult tertiary referral hospitals in Sydney, New South Wales, between February 28, 2007 and February 29, 2016. One hundred and sixty-four ECMO-facilitated transports occurred, involving 160 patients. Of these, 118 patients (74%) were treated with veno-venous (VV) ECMO and 42 patients (26%) were treated with veno-arterial ECMO. The mean (standard deviation, SD) age was 40.4 (15.0) years. Seventy-seven transports (47%) occurred within metropolitan Sydney, 52 (32%) were from rural or regional areas within NSW, 17 (10%) were interstate transfers and 18 (11%) were international transfers. Transfers were by road (58%), fixed wing aircraft (27%) or helicopter (15%). No deaths occurred during transport. The median (interquartile range) duration of ECMO treatment was 8.9 (5.2-15.3) days. One hundred and nineteen patients (74%) were successfully weaned from ECMO and 109 (68%) survived to hospital discharge or transfer. In patients treated with VV ECMO, age, sequential organ failure assessment score, pre-existing immunosuppressive disease, pre-existing diabetes, renal failure requiring dialysis and failed prone positioning prior to ECMO were independently associated with increased mortality. ECMO-facilitated patient transport is feasible, safe, and results in acceptable short-term outcomes. The NSW ECMO Retrieval Service provides specialised support to patients with severe respiratory and cardiovascular illness, who may otherwise be too unstable to undergo inter-hospital transfer to access advanced cardiovascular and critical care services.

Zinc Chloride Smoke Inhalation Induced Severe Acute Respiratory Distress Syndrome: First Survival in the United States with Extended Duration (Five Weeks) Therapy with High Dose Corticosteroids in Combination with Lung Protective Ventilation

Zinc chloride smoke bomb exposure is frequently seen in military drills, combat exercises, metal industry works, and disaster simulations. Smoke exposure presents with variety of pulmonary damage based on the intensity of the exposure. Smoke induced severe acute respiratory distress syndrome (ARDS) is often fatal and there are no standard treatment guidelines. We report the first survival of smoke induced severe ARDS in the United States (US) with prolonged use of high dose steroids (five weeks) and lung protective ventilation alone. Previously reported surviving patients in China and Taiwan required extracorporeal membrane oxygenation (ECMO) and other invasive modalities. We suggest that an extended course of high dose corticosteroids should be considered for the treatment of smoke inhalation related ARDS and should be introduced as early as possible to minimize the morbidity and mortality. We further suggest that patients with smoke inhalation should be observed in the hospital for at least 48 to 72 hours before discharge, as ARDS can have a delayed onset. Being vigilant for infectious complications is important due to prolonged steroid treatment regimen. Patients must also be monitored for critical illness polyneuromyopathy. Additionally, upper airway injury should be suspected and early evaluation by otorhinolaryngology may be beneficial.

Assessing the State of Knowledge Regarding the Effectiveness of Interventions to Contain Pandemic Influenza Transmission: A Systematic Review and Narrative Synthesis

BACKGROUND

Influenza pandemics occur when a novel influenza strain, to which humans are immunologically naïve, emerges to cause infection and illness on a global scale. Differences in the viral properties of pandemic strains, relative to seasonal ones, can alter the effectiveness of interventions typically implemented to control seasonal influenza burden. As a result, annual control activities may not be sufficient to contain an influenza pandemic.

PURPOSE

This study seeks to inform pandemic policy and planning initiatives by reviewing the effectiveness of previous interventions to reduce pandemic influenza transmission and infection. Results will inform the planning and design of more focused in-depth systematic reviews for specific types of interventions, thus providing the most comprehensive and current understanding of the potential for alternative interventions to mitigate the burden of pandemic influenza.

METHODS

A systematic review and narrative synthesis of existing systematic reviews and meta-analyses examining intervention effectiveness in containing pandemic influenza transmission was conducted using information collected from five databases (PubMed, Medline, Cochrane, Embase, and Cinahl/EBSCO). Two independent reviewers conducted study screening and quality assessment, extracting data related to intervention impact and effectiveness.

RESULTS AND DISCUSSION

Most included reviews were of moderate to high quality. Although the degree of statistical heterogeneity precluded meta-analysis, the present systematic review examines the wide variety of interventions that can impact influenza transmission in different ways. While it appears that pandemic influenza vaccination provides significant protection against infection, there was insufficient evidence to conclude that antiviral prophylaxis, seasonal influenza cross-protection, or a range of non-pharmaceutical strategies would provide appreciable protection when implemented in isolation. It is likely that an optimal intervention strategy will employ a combination of interventions in a layered approach, though more research is needed to substantiate this proposition.

TRIAL REGISTRATION

PROSPERO 42016039803.

Use of ECMO in the Management of Severe Acute Respiratory Distress Syndrome: A Survey of Academic Medical Centers in the United States

Mortality of severe acute respiratory distress syndrome (ARDS) remains high. Once conventional mechanical ventilation fails, alternative modes of therapy are used; most of which have limited evidence to support their use. No definitive guidelines exist for the management of these patients with alternate modalities of treatment. We conducted a cross-sectional national survey of 302 adult critical care training programs in the United States to understand the current preferences of intensivists regarding the use of different therapies for severe ARDS, including the use of extracorporeal membrane oxygenation (ECMO). A total of 381 responses were received: 203 critical care faculty and 174 critical care trainees. Airway pressure release ventilation was the initial choice of treatment reported by most when conventional mechanical ventilation strategy failed followed by inhaled nitric oxide and prone positioning. Extracorporeal membrane oxygenation availability was reported by 80% of the respondents at their institutions. Most respondents (83%) would consider ECMO in patients who fail optimal mechanical ventilation strategies, and the majority (60%) believed that ECMO use can facilitate lung protective ventilation, but few favored its use as a first-line modality. The majority of respondents reported limited knowledge of ECMO and desired specific ECMO education during training.

Evidence synthesis activities of a hospital evidence-based practice center and impact on hospital decision making

BACKGROUND

Hospital evidence-based practice centers (EPCs) synthesize and disseminate evidence locally, but their impact on institutional decision making is unclear.

OBJECTIVE

To assess the evidence synthesis activities and impact of a hospital EPC serving a large academic healthcare system.

DESIGN, SETTING, AND PARTICIPANTS

Descriptive analysis of the EPC's database of rapid systematic reviews since EPC inception (July 2006-June 2014), and survey of report requestors from the EPC's last 4 fiscal years.

MEASUREMENTS

Descriptive analyses examined requestor and report characteristics; questionnaire examined report usability, impact, and requestor satisfaction (higher scores on 5-point Likert scales reflected greater agreement).

RESULTS

The EPC completed 249 evidence reviews since inception. The most common requestors were clinical departments (29%, n = 72), chief medical officers (19%, n = 47), and purchasing committees (14%, n = 35). The most common technologies reviewed were drugs (24%, n = 60), devices (19%, n = 48), and care processes (12%, n = 31). Mean report completion time was 70 days. Thirty reports (12%) informed computerized decision support interventions. More than half of reports (56%, n = 139) were completed in the last 4 fiscal years for 65 requestors. Of the 64 eligible participants, 46 responded (72%). Requestors were satisfied with the report (mean = 4.4), and agreed it was delivered promptly (mean = 4.4), answered the questions posed (mean = 4.3), and informed their final decision (mean = 4.1).

CONCLUSIONS

This is the first examination of evidence synthesis activities by a hospital EPC in the United States. Our findings suggest hospital EPCs can efficiently synthesize and disseminate evidence addressing a range of clinical topics for diverse stakeholders, and can influence local decision making.

Trends in Extracorporeal Membrane Oxygenation for the Treatment of Acute Respiratory Distress Syndrome in the United States

Objectives:

Our aim was to describe patient characteristics and trends in the use of extracorporeal membrane oxygenation (ECMO) for the treatment of acute respiratory distress syndrome (ARDS) in the United States from 2006 to 2011.

Methods:

We used the Nationwide Inpatient Sample to isolate all patients aged 18 years who had a discharge International Classification of Diseases, Ninth Revision diagnosis of ARDS, with and without procedure codes for ECMO, between 2006 and 2011.

Results:

We examined a total of 47 911 414 hospital discharges, representing 235 911 271 hospitalizations using national weights. Of the 1 479 022 patients meeting the definition of ARDS (representing 7 281 206 discharges), 775 underwent ECMO. There was a 409% relative increase in the use of ECMO for ARDS in the United States between 2006 and 2011, from 0.0178% to 0.090% ( P = .0041). Patients treated with ECMO had higher in-hospital mortality (58.6% vs 25.1%, P < .0001) and longer hospital stays (15.8 days vs 6.9 days, P < .0001). They were also younger (47.9 vs 66.4 years, P < .0001) and more likely to be male (62.2% vs 49.6%, P < .0001). The median time to initiate ECMO from the time of admission was 0.5 days (interquartile range [IQR] 4.9 days).

Conclusion:

There has been a dramatic increase in ECMO use for the treatment of ARDS in the United States.

Extracorporeal life support: experience with 2,000 patients

This is a review of the University of Michigan experience with extracorporeal life support (ECLS) also known as extracorporeal membrane oxygenation (ECMO). Two thousand patients were managed with ECMO from 1973 to 2010. The first 1,000 patients were reported previously. Of the 2,000 patients, 74% were weaned from ECLS, and 64% survived to hospital discharge. In patients with respiratory failure, survival to hospital discharge was 84% in 799 neonates, 76% in 239 children, and 50% in 353 adults. Survival in patients with cardiac failure was 45% in 361 children and 38% in 119 adults. ECLS during extracorporeal cardiopulmonary resuscitation was performed in 129 patients, with 41% surviving to discharge. Survival decreased from 74 to 55% between the first and second 1,000 patients. The most common complication was bleeding at sites other than the head, with an incidence of 39%, and the least frequent complication was pump malfunction, with a 2% incidence. Intracranial bleeding or infarction occurred in 8% of patients, with a 43% survival rate. This is the largest series of ECLS at one institution reported in the world to date. Our experience has shown that ECLS saves lives of moribund patients with acute pulmonary and cardiac failure in all age groups.

Extracorporeal membrane oxygenation for blastomycosis-related acute respiratory distress syndrome: a case series

PURPOSE

Blastomyces dermatitidis is a dimorphic fungus endemic to North America capable of causing fatal respiratory failure. Acute respiratory distress syndrome (ARDS) complicates up to 10% of pulmonary blastomycosis in hospitalized patients and carries a mortality of 50-90%. This report describes the clinical course of four consecutive patients with blastomycosis-related ARDS treated with venovenous extracorporeal membrane oxygenation (ECMO) during 2009-2014.

CLINICAL FEATURES

Four adults were referred from northwestern Ontario, Canada with progressive respiratory illnesses. All patients developed diffuse bilateral opacities on chest radiography and required mechanical ventilation within 6-72 hr. Patients satisfied Berlin criteria for severe ARDS with trough PaO2/F i O2 ratios of 44-61 on positive end-expiratory pressure of 12-24 cm H2O. Wet mount microscopy from respiratory samples showed broad-based yeast consistent with B.dermatitidis. Despite lung protective ventilation strategies with maximal F i O2 (patients A-D), neuromuscular blockade (patients A-D), inhaled nitric oxide (patients A and D), and prone positioning (patient D), progressive hypoxemia resulted in initiation of venovenous ECMO by hours 24-90 of mechanical ventilation with subsequent de-escalation of ventilatory support. In all four cases, ECMO decannulation was performed (7-23 days), mechanical ventilation was withdrawn (18-52 days), and the patients survived to hospital discharge (31-87 days).

CONCLUSION

This report describes the successful application of ECMO as rescue therapy in aid of four patients with refractory blastomycosis-associated ARDS. In addition to early appropriate antimicrobial therapy, transfer to an institution experienced with ECMO should be considered when caring for patients from endemic areas with rapidly progressive respiratory failure.

Extracorporeal gas exchange for acute respiratory failure in adult patients: a systematic review

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2015 and co-published as a series in Critical Care. Other articles in the series can be found online at http://ccforum.com/series/annualupdate2015. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Extracorporeal life support for acute respiratory failure. A systematic review and metaanalysis

RATIONALE

Extracorporeal life support (ECLS) for acute respiratory failure has increased as a result of technological advancements and promising results from recent studies as compared with historical trials.

OBJECTIVES

Systematically review the effect of ECLS compared with mechanical ventilation on mortality, length of stay, and adverse events in respiratory failure.

METHODS

Data sources included were MEDLINE, EMBASE, and CENTRAL (through to October 2013). Any randomized controlled trial (RCT) or observational study comparing ECLS to mechanical ventilation in adults was used. Two authors independently abstracted the data. Our primary outcome was mortality. Secondary outcomes included intensive care unit length of stay, hospital length of stay, and adverse events. A sensitivity analysis was performed restricted to RCTs and quasi-RCTs, and a number of predefined subgroups were identified to explore heterogeneity.

MEASUREMENTS AND MAIN RESULTS

Ten studies (four RCTs, six observational studies, 1,248 patients) were included. There was no significant difference in hospital mortality with ECLS as compared with mechanical ventilation (risk ratio [RR], 1.02; 95% confidence interval [CI], 0.79-1.33; I(2) = 77%). When restricted to venovenous ECLS studies of randomized trials and quasi-randomized trials (three studies; 504 patients), there was a decrease in mortality with ECLS compared with mechanical ventilation (RR, 0.64; 95% CI, 0.51-0.79; I(2) = 15%). There were insufficient study-level data to evaluate most secondary outcomes. Bleeding was significantly greater in the ECLS group (RR, 11.44; 95% CI, 3.11-42.06; I(2) = 0%). In the H1N1 subgroup (three studies; 364 patients), ECLS was associated with significantly lower hospital mortality (RR, 0.62; 95% CI, 0.45-0.8; I(2) = 25%).

CONCLUSIONS

ECLS was not associated with a mortality benefit in patients with acute respiratory failure. However, a significant mortality benefit was seen when restricted to higher-quality studies of venovenous ECLS. Patients with H1N1-acute respiratory distress syndrome represent a subgroup that may benefit from ECLS. Future studies are needed to confirm the efficacy of ECLS as well as the optimal configuration, indications, and timing for adult patients with respiratory failure.

Extracorporeal membrane oxygenation for critically ill adults

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is a form of life support that targets the heart and lungs. Extracorporeal membrane oxygenation for severe respiratory failure accesses and returns blood from the venous system and provides non-pulmonary gas exchange. Extracorporeal membrane oxygenation for severe cardiac failure or for refractory cardiac arrest (extracorporeal cardiopulmonary resuscitation (ECPR)) provides gas exchange and systemic circulation. The configuration of ECMO is variable, and several pump-driven and pump-free systems are in use. Use of ECMO is associated with several risks. Patient-related adverse events include haemorrhage or extremity ischaemia; circuit-related adverse effects may include pump failure, oxygenator failure and thrombus formation. Use of ECMO in newborns and infants is well established, yet its clinical effectiveness in adults remains uncertain.

OBJECTIVES

The primary objective of this systematic review was to determine whether use of veno-venous (VV) or venous-arterial (VA) ECMO in adults is more effective in improving survival compared with conventional respiratory and cardiac support.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid) and EMBASE (Ovid) on 18 August 2014. We searched conference proceedings, meeting abstracts, reference lists of retrieved articles and databases of ongoing trials and contacted experts in the field. We imposed no restrictions on language or location of publications.

SELECTION CRITERIA

We included randomized controlled trials (RCTs), quasi-RCTs and cluster-RCTs that compared adult ECMO versus conventional support.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the titles and abstracts of all retrieved citations against the inclusion criteria. We independently reviewed full-text copies of studies that met the inclusion criteria. We entered all data extracted from the included studies into Review Manager. Two review authors independently performed risk of bias assessment. All included studies were appraised with respect to random sequence generation, concealment of allocation, blinding of outcome assessment, incomplete outcome data, selective reporting and other bias.

MAIN RESULTS

We included four RCTs that randomly assigned 389 participants with acute respiratory failure. Risk of bias was low in three RCTs and high in one RCT. We found no statistically significant differences in all-cause mortality at six months (two RCTs) or before six months (during 30 days of randomization in one trial and during hospital stay in another RCT). The quality of the evidence was low to moderate, and further research is very likely to impact our confidence in the estimate of effects because significant changes have been noted in ECMO applications and treatment modalities over study periods to the present.Two RCTs supplied data on disability. In one RCT survival was low in both groups but none of the survivors had limitations in their daily activities six months after discharge. The other RCT reported improved survival without severe disability in the intervention group (transfer to an ECMO centre ± ECMO) six months after study randomization but no statistically significant differences in health-related quality of life.In three RCTs, participants in the ECMO group received greater numbers of blood transfusions. One RCT recorded significantly more non-brain haemorrhage in the ECMO group. Another RCT reported two serious adverse events in the ECMO group, and another reported three adverse events in the ECMO group.Clinical heterogeneity between studies prevented meta-analyses across outcomes. We found no completed RCT that had investigated ECMO in the context of cardiac failure or arrest. We found one ongoing RCT that examined patients with acute respiratory failure and two ongoing RCTs that included patients with acute cardiac failure (arrest).

AUTHORS' CONCLUSIONS

Extracorporeal membrane oxygenation remains a rescue therapy. Since the year 2000, patient treatment and practice with ECMO have considerably changed as the result of research findings and technological advancements over time. Over the past four decades, only four RCTs have been published that compared the intervention versus conventional treatment at the time of the study. Clinical heterogeneity across these published studies prevented pooling of data for a meta-analysis.We recommend combining results of ongoing RCTs with results of trials conducted after the year 2000 if no significant shifts in technology or treatment occur. Until these new results become available, data on use of ECMO in patients with acute respiratory failure remain inconclusive. For patients with acute cardiac failure or arrest, outcomes of ongoing RCTs will assist clinicians in determining what role ECMO and ECPR can play in patient care.

Seasonal Human Influenza: Treatment Options

Seasonal influenza can be a self-limiting illness in healthy individuals but is associated with short-term morbidity and economic burden. Influenza can cause significant morbidity and mortality in young children, the elderly, pregnant and post-partum women, patients with co-morbidities and the immunocompromised. Neuraminidase inhibitors (NAIs) are the treatment of choice for influenza due to widespread resistance to the adamantanes. NAIs are efficacious for the treatment of influenza in ambulatory patients with mild illness, when initiated within 48 h of symptom onset. Early treatment with NAIs has been shown to reduce otitis media in children, and lower respiratory tract complications, resulting in antibiotic therapy, in adults. Evidence on the efficacy of NAIs for the prevention of influenza-related complications in at-risk populations, based on reviews of data from randomised trials is inconclusive. However, observational studies suggest that in hospitalised patients early treatment with NAIs has been associated with reduced mortality. NAIs should be initiated as soon as possible in patients at high-risk of influenza-related complications, with suspected or proven influenza, hospitalised patients and patients with severe or progressive disease. NAIs can be considered in previously healthy patients when therapy can be initiated within 48 h of symptom onset. In previously healthy patients, the therapeutic efficacy of oseltamivir is time-dependent, with maximal benefit observed when therapy is initiated within 48 h of symptom onset. However, several observational studies suggest therapeutic benefit beyond 48 h, in hospitalised patients, severe disease, and patients at high risk of complications, including pregnant women. NAIs should be considered in patients at high risk of influenza-related complications who present late. Further studies are needed to define the optimal timing of NAIs. Oseltamivir-resistant virus has been widely reported but is predominantly an issue in H1N1 seasonal influenza. Zanamivir-resistant influenza virus is rare, and inhaled or intravenous (IV) zanamivir is the treatment of choice in proven or suspected oseltamivir-resistant virus. Intubated patients with severe influenza can be treated with oseltamivir (suspension) administered via nasogastric tube. The commercial dry powder formulation of zanamivir should not be administered, via nebulisation, as it has been associated with ventilator malfunction and mortality. In intubated patients, when there are concerns about gastric absorption, IV zanamivir should be obtained under Emergency Investigational New Drug access schemes. Currently available evidence does not support the use of high-dose or extended-duration oseltamivir in patients with severe influenza, but does require further investigation. Extracorporeal membrane oxygenation has not been shown to be superior to conventional management in patients with influenza-associated acute respiratory distress syndrome and should be considered as salvage therapy. Corticosteriods should not be used in the treatment of severe influenza as this has been associated with increased risk of mortality and bacterial superinfection.

Clinical care for severe influenza and other severe illness in resource-limited settings: the need for evidence and guidelines

The 2009 influenza A (H1N1) pandemic highlighted the importance of quality hospital care of the severely ill, yet there is evidence that the impact of the 2009 pandemic was highest in low‐ and middle‐income countries with fewer resources. Recent data indicate that death and suffering from seasonal influenza and severe illness in general are increased in resource‐limited settings. However, there are limited clinical data and guidelines for the management of influenza and other severe illness in these settings. Life‐saving supportive care through syndromic case management is used successfully in high‐resource intensive care units and in global programs such as the Integrated Management of Childhood Illness (IMCI). While there are a variety of challenges to the management of the severely ill in resource‐limited settings, several new international initiatives have begun to develop syndromic management strategies for these environments, including the World Health Organization's Integrated Management of Adult and Adolescent Illness Program. These standardized clinical guidelines emphasize syndromic case management and do not require high‐resource intensive care units. These efforts must be enhanced by quality clinical research to provide missing evidence and to refine recommendations, which must be carefully integrated into existing healthcare systems. Realizing a sustainable, global impact on death and suffering due to severe influenza and other severe illness necessitates an ongoing and concerted international effort to iteratively generate, implement, and evaluate best‐practice management guidelines for use in resource‐limited settings.

Antiviral treatment and vaccination for influenza A(H1N1)pdm09 virus: lessons learned from the pandemic

The influenza pandemic that was declared by the World Health Organization in June 2009 created a new scenario for the use of influenza antivirals and vaccination. The new strain, influenza A(H1N1)pdm09, was resistant to amantadine and rimantadine, and the most frequently used antiviral was oseltamivir. Randomized studies were not performed comparing neuraminidase inhibitors with placebo. Nevertheless, experience from prospective and retrospective cohorts indicated that these drugs were useful for improving the prognosis of patients admitted to hospitals, especially for those with more severe disease. Treatment with oseltamivir was associated with a reduction in days of fever, length of hospital stay, use of mechanical ventilation and mortality. Treatment was more effective if it was begun within the first 48 h after the onset of symptoms, but it was also useful if begun later. A safe and effective vaccine to prevent disease from this new influenza strain was available in developed countries soon after the pandemic began; thus, the rate of adverse effects was comparable to that of seasonal influenza vaccines. The main barrier to its use was the concern of target populations about its necessity and safety. Therefore, the challenges for future pandemics will be to increase the population coverage of the vaccine in developed countries and to make it affordable for developing countries.

Clinical research during a public health emergency: a systematic review of severe pandemic influenza management

OBJECTIVE

Rigorous evaluation of clinical interventions in the setting of a public health emergency is necessary to identify best practices, to develop clinical management guidelines, and to inform resource allocation. The 2009 influenza A (H1N1) pandemic necessitated care of critically ill patients around the world. To inform the World Health Organization Public Health Research Agenda for Influenza, we conducted a systematic review to identify clinical interventions other than antiviral therapies that would benefit severely ill 2009 H1N1 influenza patients (adults and children) in both high- and low-resource settings.

DATA SOURCES

PubMed, EMBASE, Cochrane Central Register of Clinical Trials, and Cochrane Database of Systematic Reviews; hand search of abstracts from six professional society annual conferences and bibliographies of clinical review articles; and personal communication with leaders in the field.

STUDY SELECTION

English language; human studies; citations added to databases from January 1, 2009 (Cochrane databases) or March 15, 2009 (PubMed and EMBASE) through January 31, 2012; randomized controlled trials, prospective cohort studies, or systematic reviews/meta-analyses of non-antiviral clinical interventions in hospitalized 2009 influenza A (H1N1) patients.

DATA EXTRACTION

The search identified 2,452 articles. Thirty-six potentially relevant articles were read. Seven articles met criteria. All were observational studies.

DATA SYNTHESIS

One study found benefit of convalescent plasma infusion, three studies found no benefit of corticosteroids, and three studies had mixed results on the benefit of extracorporeal lung support. No study was applicable to health care delivery in low-resource settings.

CONCLUSIONS

There is a paucity of high quality clinical research to inform clinical care of severe H1N1 influenza, and we found no beneficial interventions appropriate for low-resource settings. This may be due to the logistical difficulties of conducting clinical research in response to a public health emergency. Our investigation underscores the need for the development of outbreak-ready research capacity in both high- and low-resource settings.

Lack of clinically evident signs of organ failure affects ED treatment of patients with severe sepsis

BACKGROUND

It is not known whether lack of recognition of organ failure explains the low compliance with the "Surviving Sepsis Campaign" (SSC) guidelines. We evaluated whether compliance was higher in emergency department (ED) sepsis patients with clinically recognizable signs of organ failure compared to patients with only laboratory signs of organ failure.

METHODS

Three hundred twenty-three ED patients with severe sepsis and septic shock were prospectively included. Multivariable binary logistic regression was used to assess if clinical and biochemical signs of organ failure were associated with compliance to a SSC-based resuscitation bundle. In addition, two-way analysis of variance was used to investigate the relation between the predisposition, infection, response and organ failure (PIRO) score (3 groups: 1-7, 8-14, 15-24) as a measure of illness severity and time to antibiotics with disposition to ward or ICU as effect modifier.

RESULTS

One hundred twenty-five of 323 included sepsis patients with new-onset organ failure were admitted to the ICU, and in all these patients the SSC resuscitation bundle was started. Respiratory difficulty, hypotension and altered mental status as clinically recognizable signs of organ failure were independent predictors of 100% compliance and not illness severity per se. Corrected ORs (95% CI) were 3.38 (1.08-10.64), 2.37 (1.07-5.23) and 4.18 (1.92-9.09), respectively. Septic ED patients with clinically evident organ failure were more often admitted to the ICU compared to a ward (125 ICU admissions, P < 0.05), which was associated with shorter time to antibiotics [ward: 127 (113-141) min; ICU 94 (80-108) min (P = 0.005)].

CONCLUSIONS

The presence of clinically evident compared to biochemical signs of organ failure was associated with increased compliance with a SSC-based resuscitation bundle and admission to the ICU, suggesting that recognition of severe sepsis is an important barrier for successful implementation of quality improvement programs for septic patients. In septic ED patients admitted to the ICU, the time to antibiotics was shorter compared to patients admitted to a normal ward.

Extracorporeal membrane oxygenation (ECMO) in patients with H1N1 influenza infection: a systematic review and meta-analysis including 8 studies and 266 patients receiving ECMO

Introduction

H1N1 influenza can cause severe acute lung injury (ALI). Extracorporeal membrane oxygenation (ECMO) can support gas exchange in patients failing conventional mechanical ventilation, but its role is still controversial. We conducted a systematic review and meta-analysis on ECMO for H1N1-associated ALI.

Methods

CENTRAL, Google Scholar, MEDLINE/PubMed and Scopus (updated 2 January 2012) were systematically searched. Studies reporting on 10 or more patients with H1N1 infection treated with ECMO were included. Baseline, procedural, outcome and validity data were systematically appraised and pooled, when appropriate, with random-effect methods.

Results

From 1,196 initial citations, 8 studies were selected, including 1,357 patients with confirmed/suspected H1N1 infection requiring intensive care unit admission, 266 (20%) of whom were treated with ECMO. Patients had a median Sequential Organ Failure Assessment (SOFA) score of 9, and had received mechanical ventilation before ECMO implementation for a median of two days. ECMO was implanted before inter-hospital patient transfer in 72% of cases and in most patients (94%) the veno-venous configuration was used. ECMO was maintained for a median of 10 days. Outcomes were highly variable among the included studies, with in-hospital or short-term mortality ranging between 8% and 65%, mainly depending on baseline patient features. Random-effect pooled estimates suggested an overall in-hospital mortality of 28% (95% confidence interval 18% to 37%; I² = 64%).

Conclusions

ECMO is feasible and effective in patients with ALI due to H1N1 infection. Despite this, prolonged support (more than one week) is required in most cases, and subjects with severe comorbidities or multiorgan failure remain at high risk of in-hospital death.

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 cmH(2)O) 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-January 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 cmH(2)O).

RESULTS

Fourteen patients were referred for ECMO. In seven patients PPLAT(L) was 27.2 ± 1.2 cmH(2)O; all these patients underwent ECMO. In the other seven patients, PPLAT(L) was 16.6 ± 2.9 cmH(2)O. Raising PEEP (from 17.9 ± 1.2 to 22.3 ± 1.4 cmH(2)O, P = 0.0001) to approach the upper physiological limit of transpulmonary pressure (PPLAT(L) = 25.3 ± 1.7 cm H(2)O) 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.

Critically ill patients with H1N1 influenza A undergoing extracorporeal membrane oxygenation

The most common cause of death due to the H1N1 subtype of influenza A virus (swine flu) in the 2009 to 2010 epidemic was severe acute respiratory failure that persisted despite advanced mechanical ventilation strategies. Extracorporeal membrane oxygenation (ECMO) was used as a salvage therapy for patients refractory to traditional treatment. At Legacy Emanuel Hospital, Portland, Oregon, the epidemic resulted in a critical care staffing crisis. Among the 15 patients with H1N1 influenza A treated with ECMO, 4 patients received the therapy simultaneously. The role of ECMO in supporting patients with severe respiratory failure due to H1N1 influenza is described, followed by discussions of the nursing care challenges for each body system. Variations from standards of care, operational considerations regarding staff workload, institutional burden, and emotional wear and tear of the therapy on patients, patients' family members, and the entire health care team are also addressed. Areas for improvement for providing care of the critically ill patient requiring ECMO are highlighted in the conclusion.

Use of extracorporeal life support in adults with severe acute respiratory failure

Extracorporeal membrane oxygenation (ECMO) is a recognized and accepted therapeutic option in the treatment of neonatal and pediatric respiratory failure. However, early studies in adults did not demonstrate a survival benefit associated with the utilization of ECMO for severe acute respiratory failure. Despite this historical lack of benefit, use of ECMO in adult patients has seen a recent resurgence. Local successes and a recently published randomized trial have both demonstrated promising results in an adult population with high baseline mortality and limited therapeutic options. This article will review the history of ECMO use for respiratory failure; investigate the driving forces behind the latest surge in interest in ECMO for adults with refractory severe acute respiratory failure; and describe potential applications of ECMO that will likely increase in the near future.

Clinical review: Extracorporeal membrane oxygenation

The H1N1 flu pandemic led to a wider use of extracorporeal membrane oxygenation (ECMO), proving its power in hypoxemic emergencies. The results obtained during this pandemic, more than any randomized trial, led to the worldwide acceptance of the use of membrane lungs. Moreover, as centers that applied this technique as rescue therapy for refractory hypoxemia recognized its strength and limited technical challenges, the indications for ECMO have recently been extended. Indications for veno-venous ECMO currently include respiratory support as a bridge to lung transplantation, correction of lung hyperinflation during chronic obstructive pulmonary disease exacerbation and respiratory support in patients with the acute respiratory distress syndrome, possibly also without mechanical ventilation. The current enthusiasm for ECMO in its various aspects should not, however, obscure the consideration of the potential complications associated with this life-saving technique, primarily brain hemorrhage

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.

Successful use of venovenous extracorporeal membrane oxygenation for complicated H1N1 pneumonia refractory to mechanical ventilation

In April 2009, novel H1N1 influenza A pneumonia was initially identified in young adults by the Mexican Health Ministry. Previously healthy patients progressing to multisystem organ failure were common. Worldwide, hospitals reported surges in intensive care admissions during the initial phase of the pandemic. In patients with H1N1 pneumonia refractory to mechanical ventilation, centers were initially reporting low survival rates despite the use of extracorporeal membrane oxygenation (ECMO). The initial poor outcomes and protracted ECMO treatment epochs resulted in centers limiting or withholding the use of ECMO in this population. With respect to children with H1N1 infection there was uncertainty concerning optimal incorporation of ECMO as a therapeutic option. In children with rapidly progressive pneumonia and hypoxia refractory to mechanical ventilation, venovenous (VV) ECMO has been successfully used with survival ranging from 40-60% depending on the etiology. We report the successful use of VV ECMO in two children with confirmed novel H1N1 complicated by bacterial pneumonia or morbid obesity. Our Institutional Review Board waived the need for consent. Prompt initiation of VV ECMO resulted in rapid clinical improvement, radiographic resolution of diffuse consolidation, and return of full neurocognitive function. For children with rapidly progressive respiratory distress on conventional ventilation, VV ECMO can be used to improve outcomes when initiated early in the disease process even in children with a significant co-morbidity.

An assessment of H1N1 influenza-associated acute respiratory distress syndrome severity after adjustment for treatment characteristics

Pandemic influenza caused significant increases in healthcare utilization across several continents including the use of high-intensity rescue therapies like extracorporeal membrane oxygenation (ECMO) or high-frequency oscillatory ventilation (HFOV). The severity of illness observed with pandemic influenza in 2009 strained healthcare resources. Because lung injury in ARDS can be influenced by daily management and multiple organ failure, we performed a retrospective cohort study to understand the severity of H1N1 associated ARDS after adjustment for treatment. Sixty subjects were identified in our hospital with ARDS from “direct injury” within 24 hours of ICU admission over a three month period. Twenty-three subjects (38.3%) were positive for H1N1 within 72 hours of hospitalization. These cases of H1N1-associated ARDS were compared to non-H1N1 associated ARDS patients. Subjects with H1N1-associated ARDS were younger and more likely to have a higher body mass index (BMI), present more rapidly and have worse oxygenation. Severity of illness (SOFA score) was directly related to worse oxygenation. Management was similar between the two groups on the day of admission and subsequent five days with respect to tidal volumes used, fluid balance and transfusion practices. There was, however, more frequent use of “rescue” therapy like prone ventilation, HFOV or ECMO in H1N1 patients. First morning set tidal volumes and BMI were significantly associated with increased severity of lung injury (Lung injury score, LIS) at presentation and over time while prior prescription of statins was protective. After assessment of the effect of these co-interventions LIS was significantly higher in H1N1 patients. Patients with pandemic influenza-associated ARDS had higher LIS both at presentation and over the course of the first six days of treatment when compared to non-H1N1 associated ARDS controls. The difference in LIS persisted over the duration of observation in patients with H1N1 possibly explaining the increased duration of mechanical ventilation.

We should not be complacent about our population-based public health response to the first influenza pandemic of the 21st century

Background

More than a year after an influenza pandemic was declared in June 2009, the World Health Organization declared the pandemic to be over. Evaluations of the pandemic response are beginning to appear in the public domain.

Discussion

We argue that, despite the enormous effort made to control the pandemic, it is now time to acknowledge that many of the population-based public health interventions may not have been well considered. Prior to the pandemic, there was limited scientific evidence to support border control measures. In particular no border screening measures would have detected prodromal or asymptomatic infections, and asymptomatic infections with pandemic influenza were common. School closures, when they were partial or of short duration, would not have interrupted spread of the virus in school-aged children, the group with the highest rate of infection worldwide. In most countries where they were available, neuraminidase inhibitors were not distributed quickly enough to have had an effect at the population level, although they will have benefited individuals, and prophylaxis within closed communities will have been effective. A pandemic specific vaccine will have protected the people who received it, although in most countries only a small minority was vaccinated, and often a small minority of those most at risk. The pandemic vaccine was generally not available early enough to have influenced the shape of the first pandemic wave and it is likely that any future pandemic vaccine manufactured using current technology will also be available too late, at least in one hemisphere.

Summary

Border screening, school closure, widespread anti-viral prophylaxis and a pandemic-specific vaccine were unlikely to have been effective during a pandemic which was less severe than anticipated in the pandemic plans of many countries. These were cornerstones of the population-based public health response. Similar responses would be even less likely to be effective in a more severe pandemic. We agree with the recommendation from the World Health Organisation that pandemic preparedness plans need review.