Paul Forrest

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.

Mechanical Ventilation Management During Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome: A Retrospective International Multicenter Study*

Objective:To describe mechanical ventilation settings in adult patients treated for an acute respiratory distress syndrome with extracorporeal membrane oxygenation and assess the potential impact of mechanical ventilation settings on ICU mortality. Design:Retrospective observational study. Setting:Three international high-volume extracorporeal membrane oxygenation centers. Patients:A total of 168 patients treated with extracorporeal membrane oxygenation for severe acute respiratory distress syndrome from January 2007 to January 2013. Interventions:We analyzed the association between mechanical ventilation settings (i.e. plateau pressure, tidal volume, and positive end-expiratory pressure) on ICU mortality using multivariable logistic regression model and Cox-proportional hazards model. Measurement and Main Results:We obtained detailed demographic, clinical, daily mechanical ventilation settings and ICU outcome data. One hundred sixty-eight patients (41 ± 14 years old; PaO2/FIO2 67 ± 19 mm Hg) fulfilled our inclusion criteria. Median duration of extracorporeal membrane oxygenation and ICU stay were 10 days (6–18 d) and 28 days (16–42 d), respectively. Lower positive end-expiratory pressure levels and significantly lower plateau pressures during extracorporeal membrane oxygenation were used in the French center than in both Australian centers (23.9 ± 1.4 vs 27.6 ± 3.7 and 27.8 ± 3.6; p < 0.0001). Overall ICU mortality was 29%. Lower positive end-expiratory pressure levels (until day 7) and lower delivered tidal volume after 3 days on extracorporeal membrane oxygenation were associated with significantly higher mortality (p < 0.05). In multivariate analysis, higher positive end-expiratory pressure levels during the first 3 days of extracorporeal membrane oxygenation support were associated with lower mortality (odds ratio, 0.75; 95% CI, 0.64–0.88; p = 0.0006). Other independent predictors of ICU mortality included time between ICU admission and extracorporeal membrane oxygenation initiation, plateau pressure greater than 30 cm H2O before extracorporeal membrane oxygenation initiation, and lactate level on day 3 of extracorporeal membrane oxygenation support. Conclusions:Protective mechanical ventilation strategies were routinely used in high-volume extracorporeal membrane oxygenation centers. However, higher positive end-expiratory pressure levels during the first 3 days on extracorporeal membrane oxygenation support were independently associated with improved survival. Further prospective trials on the optimal mechanical ventilation strategy during extracorporeal membrane oxygenation support are warranted.

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 Very High-risk Transcatheter Aortic Valve Implantation

BACKGROUND Transcatheter aortic valve implantation (TAVI) can cause profound haemodynamic perturbation in the peri-operative period. Veno-arterial extracorporeal membrane oxygenation (ECMO) can be used to provide cardiorespiratory support during this time, either prophylactically or emergently. METHOD 100 TAVI procedures were performed between 2009 and 2013 in our institution. ECMO was used in 11 patients, including eight prophylactic and three rescue cases. Rescue ECMO was required for ventricular fibrillation after valvuloplasty, and aortic annulus rupture. The criteria for prophylactic ECMO included heart failure requiring stabilisation pre-TAVI, haemodynamic instability with balloon aortic valvuloplasty performed to improve heart function pre-TAVI, moderate or severe left and/or right ventricular failure, or borderline haemodynamics at procedure. Differences in preoperative characteristics and postoperative outcomes between ECMO and non-ECMO TAVI patients were compared, and significant results were further assessed controlling for EuroSCORE. RESULTS Compared to TAVI patients who did not require ECMO, ECMO patients had significantly higher mean EuroSCORE (51 vs. 30%, p<.05). Postoperative outcomes, however, were largely comparable between the two groups. All-cause mortality occurred in nil prophylactic ECMO patients, one rescue ECMO patient, and two non-ECMO patients. The difference in mortality between ECMO and non-ECMO patients was not significantly different (9 vs. 2%; p>.05). ECMO patients were more likely to develop acute renal failure than non-ECMO patients (36 vs. 8%, p<.05), which was most likely due to haemodynamic collapse and end-organ dysfunction in patients that required ECMO rescue. CONCLUSIONS Instituting prophylactic ECMO in selected very high-risk patients may help avoid consequences of intra-operative complications and the need for emergent rescue ECMO.

Extracorporeal cardiopulmonary resuscitation for refractory cardiac arrest: A multicentre experience.

AIM To describe the ECPR experience of two Australian ECMO centres, with regards to survival and neurological outcome, their predictors and complications. METHODS Retrospective observational study of prospectively collected data on all patients who underwent extracorporeal cardiopulmonary resuscitation (ECPR) at two academic ECMO referral centres in Sydney, Australia. MEASUREMENTS AND MAIN RESULTS Thirty-seven patients underwent ECPR, 25 (68%) were for in-hospital cardiac arrests. Median age was 54 (IQR 47-58), 27 (73%) were male. Initial rhythm was ventricular fibrillation or pulseless ventricular tachycardia in 20 patients (54%), pulseless electrical activity (n=14, 38%), and asystole (n=3, 8%). 27 (73%) arrests were witnessed and 30 (81%) patients received bystander CPR. Median time from arrest to initiation of ECMO flow was 45min (IQR 30-70), and the median time on ECMO was 3days (IQR 1-6). Angiography was performed in 54% of patients, and 27% required subsequent coronary intervention (stenting or balloon angioplasty 24%). A total of 13 patients (35%) survived to hospital discharge (IHCA 33% vs. OHCA 37%). All survivors were discharged with favourable neurological outcome (Cerebral Performance Category 1 or 2). Pre-ECMO lactate level was predictive of mortality OR 1.35 (1.06-1.73, p=0.016). CONCLUSIONS In selected patients with refractory cardiac arrest, ECPR may provide temporary support as a bridge to intervention or recovery. We report favourable survival and neurological outcomes in one third of patients and pre-ECMO lactate levels predictive of mortality. Further studies are required to determine optimum selection criteria for ECPR.

Introduction of an interdisciplinary heart team-based transcatheter aortic valve implantation programme: short and mid-term outcomes.

Transcatheter aortic valve implantation (TAVI) has been developed to treat symptomatic aortic stenosis in patients deemed too high risk for open‐heart surgery. To address this complex population, an interdisciplinary heart team approach was proposed.

Anesthesia for Interventional Cardiology

c c a I m a m a a m THE DEMAND FOR anesthetic support for interventional cardiology procedures is increasing as the number and complexity of these procedures rapidly expand. Providing safe anesthesia care to patients undergoing these procedures requires comprehensive preoperative assessment, involvement in the multidisciplinary planning of these cases, and a detailed understanding of the procedures and their potential complications. This article reviews the common implantation and electrophysiology (EP) procedures undertaken in cardiac catheterization laboratories. An outline of the procedures undertaken and their major periprocedural complications are addressed along with recommendations for their anesthetic management. The first section covers closure of intracardiac shunts, closure of patent ductus arteriosus (PDA), left atrial appendage (LAA) occlusion devices, transcatheter valves, and the implantation and removal of pacemaker and rhythm management devices. The second section covers EP procedures and anesthetic management issues in patients with congenital heart disease (CHD). It also covers the anesthetic implications of ionizing radiation and practice in a remote location.

Neurologic injury and protection in adult cardiac and aortic surgery

EUROLOGIC INJURY can be defined as any temporary or permanent injury to the central and peripheral nervous system, including the brain, spinal cord, and peripheral nerves. This is a major perioperative complication of cardiac and aortic surgery, which can manifest as short-term coma or a state of confusion and long-term decline in cognitive function, behavioral changes, or physical dysfunction. Stroke occurs in approximately 2% to 3% of adult cardiac surgery patients. The rate of postoperative cognitive decline is less clear, due to heterogenous testing methods, but is reported in 50% to 70% of patients at 1 week, 30% to 50% at 6 weeks, and 20% to 40% at 1 year. 1,2 This review evaluates the current rationale and evidence for proposed surgical and nonsurgical techniques for the reduction of neurologic injury. A variety of mechanisms can result in perioperative neurologic injury during cardiac and aortic surgery (Table 1), and many patients have a combination of these mechanisms. This review discusses these etiologic factors in relation to the techniques proposed to reduce them. Accurate assessment techniques to determine the etiology of neurologic injury, adequacy of cerebral perfusion, and quantification of the extent of injury are essential to assess the efficacy of potential neuroprotective measures. These techniques include intraoperative near-infrared spectroscopy and transcranial Doppler; neurologic, psychological, and cognitive examination; imaging of the nervous system; and biomarkers in cerebrospinal fluid and serum. Discussion of these methods are outside the scope of this review; however, it is important to appreciate that all methods have limitations in sensitivity and/or specificity when interpreting the results of experimental and clinical studies. 3 A recent consensus statement aimed to unify definitions and classifications of neurologic injury after aortic arch surgery. 4

Neurologic Complications of Extracorporeal Membrane Oxygenation: A Review

OBJECTIVE To review the evidence on neurologic complications in adult extracorporeal membrane oxygenation (ECMO) patients with regard to incidence, pathophysiology, risk factors, diagnosis, monitoring techniques, prevention, and management. DESIGN Literature review. SETTING Observational studies and case reports from a variety of institutions. PARTICIPANTS Adult ECMO patients. INTERVENTIONS Six electronic databases were searched from their dates of inception to October 2016. MEASUREMENTS AND MAIN RESULTS The range of neurologic complications reported in adult ECMO patients included stroke, intracranial hemorrhage, and brain death. Due to a lack of standardized reporting, their true incidence may have been underestimated significantly. A variety of pathophysiologic mechanisms and risk factors have been proposed. Some of these are specific to venoarterial ECMO, whereas others may be more relevant to venovenous ECMO (eg, rapid correction of hypercarbia). With regard to diagnosis and monitoring, clinical examination alone can be challenging and insufficiently sensitive, particularly for the confirmation of brain death. Computed tomography is the main imaging modality for acute neurologic assessment because magnetic resonance imaging is not feasible in these patients. Options for neuromonitoring are limited, although cerebral near-infrared spectroscopy may be useful. There are very limited data to guide the management of specific complications such as intracranial hemorrhage, which remains a leading cause of mortality in ECMO patients. CONCLUSIONS ECMO can be lifesaving and is being used increasingly for severe respiratory and/or cardiac failure. However, it remains associated with significant neurologic morbidity and mortality. Greater research clearly is needed to determine the best approach to the assessment and management of neurologic complications in this rapidly growing patient population.

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.