Extracorporeal Membrane Oxygenation for 2009 Influenza A(H1N1) Acute Respiratory Distress Syndrome

CONTEXT

The novel influenza A(H1N1) pandemic affected Australia and New Zealand during the 2009 southern hemisphere winter. It caused an epidemic of critical illness and some patients developed severe acute respiratory distress syndrome (ARDS) and were treated with extracorporeal membrane oxygenation (ECMO).

OBJECTIVES

To describe the characteristics of all patients with 2009 influenza A(H1N1)-associated ARDS treated with ECMO and to report incidence, resource utilization, and patient outcomes.

DESIGN, SETTING, AND PATIENTS

An observational study of all patients (n = 68) with 2009 influenza A(H1N1)-associated ARDS treated with ECMO in 15 intensive care units (ICUs) in Australia and New Zealand between June 1 and August 31, 2009.

MAIN OUTCOME MEASURES

Incidence, clinical features, degree of pulmonary dysfunction, technical characteristics, duration of ECMO, complications, and survival.

RESULTS

Sixty-eight patients with severe influenza-associated ARDS were treated with ECMO, of whom 61 had either confirmed 2009 influenza A(H1N1) (n = 53) or influenza A not subtyped (n = 8), representing an incidence rate of 2.6 ECMO cases per million population. An additional 133 patients with influenza A received mechanical ventilation but no ECMO in the same ICUs. The 68 patients who received ECMO had a median (interquartile range [IQR]) age of 34.4 (26.6-43.1) years and 34 patients (50%) were men. Before ECMO, patients had severe respiratory failure despite advanced mechanical ventilatory support with a median (IQR) Pao(2)/fraction of inspired oxygen (Fio(2)) ratio of 56 (48-63), positive end-expiratory pressure of 18 (15-20) cm H(2)O, and an acute lung injury score of 3.8 (3.5-4.0). The median (IQR) duration of ECMO support was 10 (7-15) days. At the time of reporting, 48 of the 68 patients (71%; 95% confidence interval [CI], 60%-82%) had survived to ICU discharge, of whom 32 had survived to hospital discharge and 16 remained as hospital inpatients. Fourteen patients (21%; 95% CI, 11%-30%) had died and 6 remained in the ICU, 2 of whom were still receiving ECMO.

CONCLUSIONS

During June to August 2009 in Australia and New Zealand, the ICUs at regional referral centers provided mechanical ventilation for many patients with 2009 influenza A(H1N1)-associated respiratory failure, one-third of whom received ECMO. These ECMO-treated patients were often young adults with severe hypoxemia and had a 21% mortality rate at the end of the study period.

Edinburgh trial of screening for breast cancer: mortality at seven years

Between 1979 and 1981, 45,130 women in Edinburgh aged 45-64 were entered into a randomised trial of breast cancer screening by mammography and clinical examination. The initial attendance rate was 61% but this varied according to age and socioeconomic status and decreased over succeeding years. The cancer detection rate was 6.2 per 1000 women attending at the first visit; the rate fell to around 3 per 1000 in the years when mammography was routinely repeated and to around 1 per 1000 at the intervening visits with clinical examination alone as the screening method. After 7 years of follow-up the mortality reduction achieved was 17% (relative risk = 0.83, 95% CI 0.58-1.18), which was not statistically significant, even when corrected for socioeconomic status. In women aged 50 years and over a mortality reduction of 20% was achieved.

Venoarterial extracorporeal membrane oxygenation for cardiogenic shock and cardiac arrest: a meta-analysis

OBJECTIVE

To evaluate the effect of extracorporeal membrane oxygenation (ECMO) on survival and complication rates in adults with refractory cardiogenic shock or cardiac arrest.

DESIGN

Meta-analysis.

SETTING

University hospitals.

PARTICIPANTS

One thousand one hundred ninety-nine patients from 22 observational studies.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Observational studies published from the year 2000 onwards, examining at least 10 adult patients who received ECMO for refractory cardiogenic shock or cardiac arrest were included. Pooled estimates with 95% confidence intervals were calculated based on the Freeman-Tukey double-arcsine transformation and DerSimonian-Laird random-effect model. Survival to discharge was 40.2% (95% confidence intervals [CI], 33.9-46.7), while survival at 3, 6, and 12 months was 55.9% (95% CI, 41.5-69.8), 47.6% (95% CI, 25.4-70.2), and 54.4% (95% CI, 36.6-71.7), respectively. Survival up to 30 days was higher in cardiogenic shock patients (52.5%, 95% CI, 43.7%-61.2%) compared to cardiac arrest (36.2%, 95% CI, 23.1%-50.4%). Concurrently, complication rates were particularly substantial for neurologic deficits (13.3%, 95% CI, 8.3-19.3), infection (25.1%, 95%CI, 15.9-35.5), and renal impairment (47.4%, 95% CI, 30.2-64.9). Significant heterogeneity was detected, although its levels were similar to previous meta-analyses that only examined short-term survival to discharge.

CONCLUSIONS

Venoarterial ECMO can improve short-term survival in adults with refractory cardiogenic shock or cardiac arrest. It also may provide favorable long-term survival at up to 3 years postdischarge. However, ECMO also is associated with significant complication rates, which must be incorporated into the risk-benefit analysis when considering treatment. These findings require confirmation by large, adequately controlled and standardized trials with long-term follow-up.

Extracorporeal membrane oxygenation for severe ARDS in pregnant and postpartum women during the 2009 H1N1 pandemic

PURPOSE

To describe the technical challenges, efficacy, complications and maternal and infant outcomes associated with extracorporeal membrane oxygenation (ECMO) for severe adult respiratory distress syndrome (ARDS) in pregnant or postpartum patients during the 2009 H1N1 pandemic.

METHODS

Twelve critically ill pregnant and postpartum women were included in this retrospective observational study on the application of ECMO for the treatment of severe ARDS refractory to standard treatment. The study was conducted at seven tertiary hospitals in Australia and New Zealand.

RESULTS

Of the 12 patients treated with ECMO, 7 (58%) were pregnant and 5 (42%) were postpartum. Their median (interquartile range [IQR]) age was 29 (26-33) years, 6 (50%) were obese. Two patients were initially treated with veno-arterial (VA) ECMO. All others received veno-venous (VV) ECMO with one or two drainage cannulae. ECMO circuit-related complications were rare, circuit change was needed in only two cases and there was no sudden circuit failure. On the other hand, bleeding was common, leading to relatively large volumes of packed red blood cell transfusion (median [IQR] volume transfused was 3,499 [1,451-4,874] ml) and was the main cause of death (three cases). Eight (66%) patients survived to discharge and seven were ambulant, with normal oxygen saturations. The survival rate of infants whose mothers received ECMO was 71% and surviving infants were discharged home with no sequelae.

CONCLUSIONS

The use of ECMO for severe ARDS in pregnant and postpartum women was associated with a 66% survival rate. The most common cause of death was bleeding. Infants delivered of mothers who had received ECMO had a 71% survival rate and, like their mothers, had no permanent sequelae at hospital discharge.

Cost effectiveness and quality of life analysis of extracorporeal cardiopulmonary resuscitation (ECPR) for refractory cardiac arrest

BACKGROUND

The use of extracorporeal membrane oxygenation (ECMO) in refractory cardiac arrest (ECPR) has increased exponentially. ECPR is a resource intensive service and its cost effectiveness has yet to be demonstrated. We sought to complete a cost analysis with modelling of cost effectiveness and quality of life outcomes. We sought to complete a cost analysis with modelling of cost effectiveness and quality of life outcomes of patients who have undergone ECPR.

METHODS

Using data on all extracorporeal cardiopulmonary resuscitation (ECPR) patients at two ECMO centres in Sydney, Australia; we completed a costing analysis of ECPR patients. A Markov model of cost, quality of life and survival outcomes was developed to examine cost per QALY estimates and incremental cost effectiveness ratios (ICERs). Probabilistic sensitivity analysis (PSA) was completed to assess the probability of cost effectiveness for base case and variations.

RESULTS

Sixty-two consecutive ECPR patients were analysed; mean age of 51.9 ± 13.6 years, 38 (61%) were in hospital cardiac arrests (IHCA). Twenty-five patients (40%) survived to hospital discharge; all with a cerebral performance category (CPC) of 1 or 2. The mean cost per ECPR patient was AUD 75,165 (€50,535; ±AUD 75,737). Over 10 years ECPR was estimated to add a mean gain of 3.0 Quality Adjusted Life Years (QALYs) per patient with an incremental cost effectiveness ratio (ICER) of AUD 25,212 (€16,890) per QALY, increasing to 4.0 QALYs and an ICER of AUD 18,829 (€12,614) over a 15-year survival scenario. Mean cost per QALY did not differ significantly by OHCA or IHCA.

CONCLUSIONS

ECMO support for refractory cardiac arrests is cost effective and compares favourably to accepted cost effectiveness thresholds.

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.

Use of vasopressin after Caesarean section in idiopathic pulmonary arterial hypertension

We report the successful use of vasopressin in the management of hypotension in association with severe right ventricular (RV) failure in two patients with advanced idiopathic pulmonary arterial hypertension. Both patients were pregnant and developed systemic hypotension after delivery by Caesarean section. Placental autotransfusion and possibly oxytocin use were thought to be the major contributing factors in worsening RV function. After the use of vasopressin in both patients, cardiovascular variables improved without untoward effect on RV function, and provided rescue therapy for systemic hypotension in this setting. Vasopressin, a direct vasopressor acting via V1 receptors on the vascular endothelium, has been shown to cause pulmonary vasodilatation experimentally and in animal models of pulmonary hypertension. Its synthetic analogue, terlipressin, has been shown to reduce pulmonary vascular resistance in humans with cirrhosis. Vasopressin may therefore have differential effects on the pulmonary and systemic circulations, allowing systemic pressure to be supported without detrimental effects on the pulmonary circulation.

Anaesthesia and right ventricular failure

Acute right ventricular (RV) failure has until recently received relatively little attention in the cardiology, critical care or anaesthesia literature. However, it is frequently encountered in cardiac surgical cases and is a significant cause of mortality in patients with severe pulmonary hypertension who undergo non-cardiac surgery. RV dysfunction may be primarily due to impaired RV contractility, or volume or pressure overload. In these patients, an increased pulmonary vascular resistance (PVR) or a decreased aortic root pressure may lead to RV ischaemia, resulting in a rapid, downward haemodynamic spiral. The key aspects of 'RV protection' in patients who are at risk of perioperative decompensation are prevention, detection and treatment aimed at reversing the underlying pathophysiology. Minimising PVR and maintaining systemic blood pressure are of central importance in the prevention of RV decompensation, which is characterised by a rising central venous pressure and a falling cardiac output. Although there are no outcome data to support any therapeutic strategy for RV failure when PVR is elevated, the combination of inhaled iloprost or intravenous milrinone with oral sildenafil produces a synergistic reduction in PVR, while sparing systemic vascular resistance. Levosimendan is a promising new inotrope for the treatment of RV failure, although its role in comparison to older agents such as dobutamine, adrenaline and milrinone has yet to be determined. This is also the case for the use of vasopressin as an alternative pressor to noradrenaline. If all else has failed, mechanical support of the RV should be considered in selected cases.

Characterization of an acute micromegakaryocytic leukaemia: evidence for the pathogenesis of myelofibrosis

The current hypothesis for the pathogenesis of myelofibrosis involves the intramedullary release of growth factors from defective or abnormal megakaryocytes. We describe a case of an acute micromegakaryocytic leukaemia, in a patient with chronic myelofibrosis, that provides additional evidence for this concept. The micromegakaryocytes, which reached 223 x 10(9)/l, were characterized morphologically by both light and electron microscopy, immunocytochemically and by platelet peroxidase activity. The cells were shown to have a mature cytoplasm, containing alpha granules and the associated proteins; vWF:Ag, fibrinogen, fibronectin and protein S. DNA analysis, by both a Seescan Solitaire Plus image analysis system and flow cytometry, revealed nuclear immaturity, with 92% of cells being diploid. Serum markers of connective tissue synthesis, namely carboxy terminal peptide of procollagen I (PICP), procollagen terminal peptide III (PIIIP) and laminin all increased significantly following transformation and were associated with an increase in platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF-beta). These observations support the current hypothesis for bone marrow fibrosis formation and provide, for the first time, a link between in vivo growth factor release, bone marrow stromal turnover and megakaryocyte mass. In addition, the release of biologically active TGF-beta may explain both the increased fibronectin and angiogenesis characteristic of myelofibrotic bone marrow.

Flow mixing during peripheral veno-arterial extra corporeal membrane oxygenation - A simulation study

Peripheral veno-arterial extra-corporeal membrane oxygenation (ECMO) is an artificial circulation that supports patients with severe cardiac and respiratory failure. Differential hypoxia during ECMO support has been reported, and it has been suggested that it is due to the mixing of well-perfused retrograde ECMO flow and poorly-perfused antegrade left ventricle (LV) flow in the aorta. This study aims to quantify the relationship between ECMO support level and location of the mixing zone (MZ) of the ECMO and LV flows. Steady-state and transient computational fluid dynamics (CFD) simulations were performed using a patient-specific geometrical model of the aorta. A range of ECMO support levels (from 5% to 95% of total cardiac output) were evaluated. For ECMO support levels above 70%, the MZ was located in the aortic arch, resulting in perfusion of the arch branches with poorly perfused LV flow. The MZ location was stable over the cardiac cycle for high ECMO flows (>70%), but moved 5cm between systole and diastole for ECMO support level of 60%. This CFD approach has potential to improve individual patient care and ECMO design.

In-Depth Extracorporeal Cardiopulmonary Resuscitation in Adult Out-of-Hospital Cardiac Arrest

The use of extracorporeal cardiopulmonary resuscitation (E‐CPR) for the treatment of patients with out‐of‐hospital cardiac arrest who do not respond to conventional cardiopulmonary resuscitation CPR) has increased significantly in the past 10 years, in response to case reports and observational studies reporting encouraging results. However, no randomized controlled trials comparing E‐CPR with conventional CPR have been published to date. The evidence from systematic reviews of the available observational studies is conflicting. The inclusion criteria for published E‐CPR studies are variable, but most commonly include witnessed arrest, immediate bystander CPR, an initial shockable rhythm, and an estimated time from CPR start to establishment of E‐CPR (low‐flow time) of <60 minutes. A shorter low‐flow time has been consistently associated with improved survival. In an effort to reduce low‐flow times, commencement of E‐CPR in the prehospital setting has been reported and is currently under investigation. The provision of an E‐CPR service, whether hospital based or prehospital, carries considerable cost and technical challenges. Despite increased adoption, many questions remain as to which patients will derive the most benefit from E‐CPR, when and where to implement E‐CPR, optimal post‐arrest E‐CPR care, and whether this complex invasive intervention is cost‐effective. Results of ongoing trials are awaited to determine whether E‐CPR improves survival when compared with conventional CPR.

Left ventricular decompression in veno-arterial extracorporeal membrane oxygenation

Background

Despite the survival benefit of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) for treatment of refractory cardiogenic shock, it can also have potentially deleterious effects of left ventricular overload and pulmonary edema. The objective of this review was to investigate the current evidence on the incidence, diagnosis, risk factors, prevention, and interventions for left ventricular overload in adult and pediatric VA-ECMO patients.

Methods

Five electronic databases, including MEDLINE, EMBASE, PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), and Cochrane Database of Systematic Reviews, were searched for original published studies from their dates of inception to January 2018. All types of adult and pediatric studies that investigated LV overload in VA-ECMO and were published in the English language were reviewed. Exclusion criteria included abstracts and conference presentations.

Results

The reported incidence and sequelae of LV overload in VA-ECMO are highly variable, with presentations ranging from pulmonary arterial diastolic pressures of greater than 25 mmHg and LV distention on echocardiography, to severe pulmonary edema, LV thrombosis, and refractory ventricular arrhythmias. Currently, there are no standardized diagnostic criteria or guidelines for the type and timing of intervention for LV overload. Techniques for LV decompression have included direct surgical LV venting with catheter insertion via sternotomy or a minimally invasive incision; percutaneous catheterization via a transaortic, transseptal, or transpulmonary approach; ventricular assist devices; and intra-aortic balloon pumps.

Conclusions

Left ventricular volume distention is a significant problem in VA-ECMO patients, with sequelae including myocardial ischemia, severe pulmonary edema, and intracardiac thrombosis. Further research is required on its incidence, diagnostic criteria, and risk factors, as well as the optimal timing and method for LV decompression, given the diversity of surgical and percutaneous techniques that are available.

Vasopressin and shock

Vasopressin (antidiuretic hormone) is emerging as a potentially major advance in the treatment of a variety of shock states. Increasing interest in the clinical use of vasopressin has resulted from the recognition of its importance in the endogenous response to shock and from advances in understanding of its mechanism of action. From animal models of shock, vasopressin has been shown to produce greater blood flow diversion from non-vital to vital organ beds (particularly the brain) than does adrenaline. Although vasopressin has similar direct actions to the catecholamines, it may uniquely also inhibit some of the pathologic vasodilator processes that occur in shock states. There is current interest in the use of vasopressin in the treatment of shock due to ventricular fibrillation, hypovolaemia, sepsis and cardiopulmonary bypass. This article reviews the physiology and pharmacology of vasopressin and all of the relevant animal and human clinical literature on its use in the treatment of shock following a MEDLINE (1966-2000) search.

A computational framework for adjusting flow during peripheral extracorporeal membrane oxygenation to reduce differential hypoxia

Peripheral veno-arterial extra corporeal membrane oxygenation (VA-ECMO) is an established technique for short-to-medium support of patients with severe cardiac failure. However, in patients with concomitant respiratory failure, the residual native circulation will provide deoxygenated blood to the upper body, and may cause differential hypoxemia of the heart and brain. In this paper, we present a general computational framework for the identification of differential hypoxemia risk in VA-ECMO patients. A range of different VA-ECMO patient scenarios for a patient-specific geometry and vascular resistance were simulated using transient computational fluid dynamics simulations, representing a clinically relevant range of values of stroke volume and ECMO flow. For this patient, regardless of ECMO flow rate, left ventricular stroke volumes greater than 28 mL resulted in all aortic arch branch vessels being perfused by poorly-oxygenated systemic blood sourced from the lungs. The brachiocephalic artery perfusion was almost entirely derived from blood from the left ventricle in all scenarios except for those with stroke volumes less than 5 mL. Our model therefore predicted a strong risk of differential hypoxemia in nearly all situations with some residual cardiac function for this combination of patient geometry and vascular resistance. This simulation highlights the potential value of modelling for optimising ECMO design and procedures, and for the practical utility for personalised approaches in the clinical use of ECMO.

Placebo controlled comparison of midazolam, triazolam and diazepam as oral premedicants for outpatient anaesthesia

Two short-acting benzodiazepines, midazolam 15 mg and triazolam 0.25 mg, were compared with diazepam 10 mg and placebo as oral premedicants in 120 patients presenting for minor urological surgery. Midazolam was found to produce the greatest degree of amnesia and sedation at the time of anaesthetic induction and triazolam was found to have the greatest degree of residual sedation at the time of discharge, four hours postoperatively. These effects are consistent with the greater potency and more rapid onset of action of midazolam at this dose compared with triazolam. The relative merits of the compounds as anxiolytics varied depending upon the observer, time and method of assessment. It was considered that the doses of midazolam and triazolam used were excessive for routine day case anaesthesia.

Comparison of propofol and antagonised midazolam anaesthesia for day-case surgery

A technique of midazolam/fentanyl/isoflurane/nitrous oxide anaesthesia, in which the benzodiazepine was antagonised by the specific antagonist, flumazenil, was compared with propofol/fentanyl/nitrous oxide anaesthesia for minor outpatient urological surgery. No significant difference was found in the overall ease of anaesthesia; however, using subjective (linear analogue sedation scales) and objective (letter deletion and simple reflex time) tests, recovery was found to be significantly slower for the antagonised midazolam group. For both groups, the most frequent intraoperative problem was patient movement in response to surgical stimulation and, postoperatively, headache. The midazolam group displayed the greatest degree of residual sedation at the 4-hour time of discharge and on arrival home a significantly larger number of patients in the midazolam group slept for a period. It is likely that the dose of flumazenil chosen (1 mg) was inadequate to completely antagonise the dose of midazolam (mean 17 mg) for the full duration of recovery.

Geriatric cardiac surgery: chronology vs. biology

Cardiac surgery is increasingly performed in elderly patients, and whilst the incidence of common risk factors associated with poorer outcome increases with age, recent studies suggest that outcomes in this population may be better than is widely appreciated. As such, in this review we have examined the current evidence for common cardiac surgical procedures in patients aged over 70 years. Coronary artery bypass grafting (CABG) in the elderly has similar early safety to percutaneous intervention, though repeat revascularisation is lower. Totally avoiding instrumentation of the ascending aorta with off-pump techniques may also reduce the incidence of neurological injury. Aortic valve replacement (AVR) significantly improves quality of life and provides excellent short- and long-term outcomes. Combined AVR and CABG carries higher risk but late survival is still excellent. Mini-sternotomy AVR in the elderly can provide comparable survival to full-sternotomy AVR. More accurate risk stratification systems are needed to appropriately select patients for transcatheter aortic valve implantation. Mitral valve repair is superior to replacement in the elderly, although choosing the most effective method is important for achieving maximal quality of life. Minimally-invasive mitral valve surgery in the elderly has similar postoperative outcomes to sternotomy-based surgery, but reduces hospital length of stay and return to activity. In operative candidates, surgical repair is superior to percutaneous repair. Current evidence indicates that advanced age alone is not a predictor of mortality or morbidity in cardiac surgery. Thus surgery should not be overlooked or denied to the elderly solely on the basis of their "chronological age", without considering the patient's true "biological age".

Cost-effectiveness of extracorporeal cardiopulmonary resuscitation for adult out-of-hospital cardiac arrest: A systematic review

OBJECTIVE

The use of extracorporeal cardiopulmonary resuscitation (ECPR) for out-of-hospital cardiac arrests (OHCA) has increased dramatically over the past decade. ECPR is resource intensive and costly, presenting challenges for policymakers. We sought to review the cost-effectiveness of ECPR compared with conventional cardiopulmonary resuscitation (CCPR) in OHCA.

METHODS

We searched Medline, Embase, Tufts CEA registry and NHS EED databases from database inception to 2021 or 2015 for NHS EED. Cochrane Covidence was used to screen and assess studies. Data on costs, effects and cost-effectiveness of included studies were extracted by two independent reviewers. Costs were converted to USD using purchasing power parities (OECD, 2022).¹ The Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist (Husereau et al., 2022)² was used for reporting quality and completeness of cost-effectiveness studies; the review was registered on PROSPERO, and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Four studies met the inclusion criteria; three cost-effectiveness studies reported an incremental cost-effectiveness ratio (ICER) for OHCA compared with conventional care, and one reported the mean operating cost of ECPR. ECPR was more costly, accrued more life years (LY) and quality-adjusted life years (QALYs) than CCPR and was more cost-effective when compared with CCPR and other standard therapies. Overall study quality was rated as moderate.

CONCLUSION

Few studies have examined the cost-effectiveness of ECPR for OHCA. Of those, ECPR for OHCA was cost-effective. Further studies are required to validate findings and assess the cost-effectiveness of establishing a new ECPR service or alternate ECPR delivery models.

International Retrieval of Adults on Extracorporeal Membrane Oxygenation Support

A retrieval service was established in New South Wales to provide mobile extracorporeal membrane oxygenation support to patients with severe, acute cardiac or respiratory failure. This service has also retrieved four adult patients from Nouméa, New Caledonia to Sydney on extracorporeal membrane oxygenation support, which are the first international retrievals of this type from Australia. We discuss our experience with these patients, three of whom survived to hospital discharge. However, one patient referred from New Caledonia died before extracorporeal membrane oxygenation could be established.

Elective Use of Veno-venous Extracorporeal Membrane Oxygenation and High-flow Nasal Oxygen for Resection of Subtotal Malignant Distal Airway Obstruction

We describe the use of peripheral veno-venous extracorporeal membrane oxygenation (VV ECMO) and high-flow nasal oxygen as procedural support in a patient undergoing debulking of a malignant tumour of the lower airway. Due to the significant risk of complete airway obstruction upon induction of anaesthesia, ECMO was established while the patient was awake, and was maintained without systemic anticoagulation to minimise the risk of intraoperative bleeding. This case illustrates that ECMO support with high-flow nasal oxygen can be considered as part of the algorithm for airway management during surgery for subtotal lower airway obstruction, as it may be the only viable option for maintaining adequate gas exchange.