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ORIGINAL ARTICLES

Outcomes of the first 30 cases of an adult extracorporeal membrane oxygenation program: strategies to manage the “learning curve” and implications for intensive care unit risk adjustment models

Daniel V Mullany, Taressa N Bull, William Hunt, Kiran Shekar,Bruce Thomson, John F Fraser and Marc Ziegenfuss

Crit Care Resusc ISSN: 1441-2772 1 June2012 14 2 119-129©Cr i t Ca re Resusc 2012www.jficm.anzca.edu.au/aaccm/journal/publi-cations.htmOriginal articles

ventilatory support has failed. The role of ECMOsupport also remains controversial and outcomeble.17-21 ECMO has been used to support chrefractory septic shock.22

At the first presentation of the CESAR trial, Dr HDirector of the ECMO program at the Children’sPittsburgh, Pennsylvania, United States, said “I th

Critical Care and Resuscitation V

ABSTRACT

Background: We established an adult extracorporeal membrane oxygenation (ECMO) service for cardiorespiratory support in April 2009. Complex therapies may show a learning curve and volume–outcome relationship.Objectives: To describe our model of care, casemix and outcomes for the first 30 cases together with unique features of this service and potential strategies to manage the learning curve.Methods: Data were obtained from the intensive care unit database, medical record and minutes of multidisciplinary ECMO review meetings.Results: The model of care was based heavily on that used at an experienced ECMO centre following Extracorporeal Life Support Organization guidelines. ECMO was established as an ICU-managed, multidisciplinary service with collaboration from other specialties using standardised policies and procedures, staff training and formal case review. A specific budget was allocated to training and education and a clinical perfusionist was present on site for the first 10 cases. Seventeen patients received venoarterial (VA) and 13 received venovenous (VV) ECMO. Median duration of ECMO was 7 days for VA and 15 days for VV ECMO. Median ICU stay was 22 days. Twenty patients were referred from 13 hospitals throughout Queensland. Hospital mortality was 47% for VA ECMO and 15% for VV ECMO. The unique features of this service are the use of a Levitronix CentriMag system as well as the Rotaflow system, and the use of extended daily haemodiafiltration using the Fresenius 4008s ARrT plus connected into the ECMO circuit. The clinical implications of conducting plasma exchange and sustained low-efficiency dialysis via direct ECMO circuit connection using the Fresenius ARrT machine, and using a second system for ECMO support, were notable challenges.Conclusion: Satisfactory outcomes were achieved using an ICU-based multidisciplinary approach with a broadly based education strategy with additional clinical perfusionist support

Crit Care Resusc 2012; 14: 119–129

to manage the learning curve.

The role of extracorporeal membrane oxygenation (ECMO)in respiratory failure in adults is subject to considerabledebate.1-4 The Conventional Ventilation or ECMO for SevereAdult Respiratory Failure (CESAR) trial,5 together with caseseries,6-16 suggest a role for ECMO in highly selected, high-risk patients for whom conventional maximal mechanical

in cardiacs are varia-ildren with

eidi Dalton, Hospital ofink the fear

that a lot of us have with ECMO is that there is a learningcurve, and it is not something that hospitals can implementwithout preparation,” she said. “We need to focus on provid-ing training and teach people how to deliver ECMO.”23

Complex therapies may show evidence of a volume–outcomerelationship, although this is also debated.24

In this study, we aimed to review and discuss outcomes ofthe first 30 adult patients placed on ECMO at The PrinceCharles Hospital (TPCH), Brisbane, Queensland, Australia, andthe lessons learnt after the commencement of an adult ECMOprogram.

Abbreviations

APACHE Acute Physiology and Chronic Health Evaluation

ARDS Acute respiratory distress syndrome

CESAR Conventional Ventilation or ECMO for Severe Adult Respiratory Failure

ECMO Extracorporeal membrane oxygenation

ELSO Extracorporeal Life-Support Organization

OT Operating theatre

RA Right atrium

SOFA Sequential Organ Failure Assessment

TPCH The Prince Charles Hospital

VA Venoarterial

VPa Venopulmonary artery

VV Venovenous

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Methods

All patients undergoing ECMO from April 2009 to February2011 at TPCH were included. Data were collected contempo-raneously with the intensive care unit admission. Data collec-tion instruments were adapted from Australian and NewZealand Intensive Care Society Centre for Outcome andResource Evaluation, Australia and New Zealand ECMO andExtracorporeal Life Support Organization (ELSO) data registryforms. Data were collected during ICU and hospital admis-sion by DM, TB or trained data collectors from the ICUresearch and data management unit. Definitions are providedin Box 1. Summary statistics were used to describe thesample. The study was approved by The Prince CharlesHospital Human Research and Ethics Committee as a low-riskproposal with waived patient consent (approval no. HREC/11/QPCH/130) and by the Queensland Health, Research,Ethics and Governance Unit (approval no. RD002919).

Results

Of the first 30 patients, one had venopulmonary artery(VPa) ECMO, 13 had venovenous (VV) ECMO, and 16 hadvenoarterial (VA) ECMO. During the study period, threepatients were retrieved by New South Wales or VictorianECMO retrieval services, and since 2007, five patients havebeen retrieved. Brief clinical descriptions are shown in Table1 and Table 2. Patients 15, 16 and 20 had two ECMO runs,resulting in a total of 33 ECMO runs. Twenty patients werereferred from 13 hospitals, eight were emergency admis-sions to this hospital through the Department of EmergencyMedicine (this includes transplant patients) and two wereelective admissions. The median age was 43 years (range,16–77 years) and 14/30 were men. Demographic data andillness severity are shown in Table 3 and Table 4. The medianAcute Physiology and Chronic Health Evaluation (APACHE)II score was 19 (range, 9–39) and median APACHE III scorewas 79 (range, 48–128). The median APACHE III risk ofdeath was 0.39 (range, 0.04–0.91).

Extracorporeal membrane oxygenation program model of careThe ECMO program was modelled as closely as possible onthat developed at the Alfred Hospital, Victoria, Australia,where ECMO has been used since 1990.25 Similar policies,procedures and unit guidelines now exist in virtually allhospitals performing ECMO in Australia, and virtually iden-tical equipment is used.6

The ECMO program at TPCH is a multidisciplinary collab-oration involving staff from intensive care, anaesthesia andperfusion, cardiac surgery, cardiology and thoracic medi-cine. The ECMO program is the responsibility of theintensive care service and functions under the terms of

reference of the mechanical cardiac support working group.Equipment maintenance and supply is the responsibility ofthe perfusion service, and disposables are ordered throughthe usual operating theatre (OT) processes to accuratelytrack stock as ECMO may be required in the OT or ICU.Several intensive care specialists and all cardiac surgeons arecredentialled for ECMO cannulation. All patients with respi-ratory failure requiring ECMO receive a mandatory consul-tation from a thoracic physician from the QueenslandCentre for Pulmonary Transplantation and Vascular Disease,who takes over care when the patient is discharged to theward. In cases of cardiac failure requiring ECMO, consulta-tion is obtained from a cardiologist from the AdvancedHeart Failure and Cardiac Transplant Service, who takesover care or continues consultation when the patient isdischarged to the ward. The program submits patient datato ELSO for benchmarking.

Clinical perfusionists were present on site for the first10 cases. This clearly added to the initial costs, but wasfactored into the set-up costs and provided invaluablesupport when there were three patients on ECMO at

Box 1. Definitions

Peripheral extracorporeal membrane oxygenation (ECMO) was defined as access outside the thorax (eg, femoral, axillary, jugular, carotid vessels).

Pulmonary compliance was defined as tidal volume/(plateau pressure positive end-expiratory pressure) in mL/cm H2O. The type of ventilation mode will effect the interpretation. For pressure-controlled ventilation, peak pressure and plateau pressure were considered the same.

Inotropes were defined as milrinone or adrenaline (any dose) and > 5g/kg/min dopamine or dobutamine.

Vasopressors were defined as > 0.05 g/kg/min noradrenaline, or any vasopressin.

ECMO hours were calculated from time of insertion to time of removal. When the system was placed in the operating theatre, time was recorded from the time of admission to intensive care unit.

Ventilation and ICU hours were recorded from the time of admission to ICU at the Prince Charles Hospital (TPCH).

ICU and hospital days were recorded for TPCH only and excluded days in the referring hospital in those transferred. Most patients were transferred from acute care to subacute care. Subacute care days at TPCH were included in total hospital days, but not subacute days at other hospitals.

Sequential Organ Failure Assessment scores were calculated according to the day of ICU admission not from commencement of ECMO. Most patients were placed on ECMO within 48 hours of admission to this ICU. The pre-ECMO Glasgow Coma Scale score was used and therefore was assumed to be 15; only one patient received points for the neurological subcategory.

Blood product use was recorded as the number released by the Hospital Blood Bank and not returned. For surgical patients, this includes units transfused during surgery.

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Table 2. Clinical background and diagnosis: venovenous cases

Patient Brief clinical description APACHE III diagnosis

2 Pulmonary haemorrhage syndrome (Wegener granulomatosis) Pulmonary haemorrhage

3 Pandemic (H1N1) 2009 influenza pneumonitis; acute respiratory distress syndrome (ARDS) Viral pneumonia

4 Pneumococcal and Haemophilus bacterial pneumonia; septic shock; multiple organ failure (MOF); complicating H1N1 pneumonitis; ARDS

Bacterial pneumonia

5 Lobar pneumonia complicating H1N1 pneumonitis; ARDS Viral pneumonia

6 H1N1 pneumonitis; ARDS Viral pneumonia

7 Group A Streptococcus pneumonia; septic shock; ARDS; MOF; complicating H1N1 pneumonitis Bacterial pneumonia

9 Hyperacute rejection complicating bilateral sequential single lung transplant Thoracic surgery other

11 Pneumonia; septic shock; ARDS; MOF; no pathogen identified Sepsis with shock

12 Pneumonia; septic shock; ARDS, MOF; no pathogen identified Sepsis with shock

21 H1N1 pneumonitis; ARDS; acute renal failure Viral pneumonia



30 H1N1 pneumonitis; ARDS Viral pneumonia

Table 1. Clinical background and diagnosis: venoarterial cases

Patient Brief description APACHE III diagnosis

1 Perioperative myocardial infarction and cardiac arrests complicating CABG Cardiogenic shock

8 Cardiac arrest; myocarditis Cardiogenic shock

10 Primary graft dysfunction complicating multiorgan transplant Cardiovascular surgery other

13 Non-STEMI; cardiogenic shock; emergency CABG; failure to wean from cardiopulmonary bypass CABG

14 Late presentation anterior myocardial infarction; cardiogenic shock; percutaneous coronary intervention Cardiogenic shock

15 Temporary right ventricular assist device support for long-term left ventricular assist device Cardiovascular surgery other

16 Out-of-hospital cardiac arrest; anterior myocardial infarction; percutaneous coronary intervention; cardiogenic shock; Haemophilus pneumonia

Cardiogenic shock

17 Redo CABG; failure to wean from cardiopulmonary bypass; contraindication to intra-aortic balloon pump CABG

18 Late-presentation anterior STEMI; cardiogenic shock; emergency CABG, AVR and MVSx; recurrent refractory postoperative ventricular tachycardia and cardiac arrests

Cardiogenic shock

19 Group A Streptococcus pneumonia; myocarditis; multiple organ failure Bacterial pneumonia

20 Late-presentation inferoposterior myocardial infarction; postinfarction ventricular septal defect; cardiogenic shock; pre- and postoperative support for ventricular septal defect repair, MVR and CABG

Cardiogenic shock

22 Left main coronary artery occlusion Day 8 after third time redo AVR; cardiac arrest; emergency CABG in intensive care unit; failure to wean from cardiopulmonary bypass

Cardiogenic shock

25 Anterior myocardial infarction; left main disease; percutaneous coronary intervention to left anterior descending artery; no reflow; cardiac arrest; emergency CABG; failure to wean from bypass

Cardiogenic shock

26 Cardiogenic shock; on transplant waiting list, “bridge to bridge” Cardiogenic shock

27 Cardiogenic shock; emergency AVR, CABG and MVSx; unable to separate from cardiopulmonary bypass Cardiac valve surgery

28 Bilateral sequential single lung transplantation; primary graft dysfunction; perioperative severe biventricular failure

Thoracic surgery other

29 Cardiogenic shock; emergency MVR, tricuspid valve surgery and CABG Cardiac valve surgery

APACHE = Acute Physiology and Chronic Health Evaluation. AVR = aortic valve replacement. CABG = coronary artery bypass graft. MVR = mitral valve replacement. MVSx = mitral valve surgery. STEMI = ST elevation myocardial infarction.

ORIGINAL ARTICLES

once. Specific protocols defined nursing and perfusionroles with regard to circuit access. The negative pressurepart of the circuit was not accessed for dialysis orplasmapheresis. There were no equipment-related prob-lems when a perfusionist was on site. Procedures on

ECMO were minimised and only performed byspecialists.

A specific budget was allocated to training. Allcredentialled intensive care specialists and clinicalnurses attended structured workshops at the AlfredHospital. A series of planning meetings were heldbefore the program commenced, including dry andwet runs, and with practice cannulation by the inten-sive care specialists. A formal review of each case,focusing on the conduct of cannulation, complica-tions, system and organisational issues was conductedafter each case and at the monthly ECMO meeting. Itwas intended that only nursing staff who had under-gone specific ECMO training would care for thepatient; however, at times, other nurses acted as a“float” between patients when three patients wereon ECMO at once. Nursing ratios of up to 2 : 1 wereused initially for patients who required titratingvasoactive medicines, renal replacement therapy and/or plasmapheresis while on ECMO. On two occasions,there were three patients on ECMO for several daysduring the 2009 influenza (H1N1) pandemic and thensubsequently, unrelated to H1N1.

In all patients undergoing peripheral cannulation, atransoesophageal echocardiogram was performed at thetime of cannulation to position cannulae and assess cardiacfunction. An ECMO-trained intensive care specialistreviewed each patient each day. A separate intensive carespecialist on-call roster was required.

Table 4. Demographic and illness severity data

Venovenous Venoarterial*

Median age, years (range) 35 (18–55) 54 (16–77)

Male, no. (%) 6 (46%) 12 (71%)

Prior cardiac arrest, no. (%) 1 (7%) 7 (40%)

Median APACHE II score (range) 20 (16–35) 21 (9–39)

Median APACHE III score (range) 80 (51–123) 79 (48–128)

Median APACHE III risk of death (range) 0.39 (0.13–0.73) 0.36 (0.04–0.91)

Median SOFA score

Day 1 (range) 10 (6–16) 10 (6–16)

Day 3 (range) 10 (5–17) 10 (4–17)

Day 5 (range) 9 (4–14) 10 (5–11)

Pre ECMO, median (range)

Creatinine, mol/L 166 (35–422) 127 (65–383)

Bilirubin, mmol/L 20 (4–189) 35 (6– 101)

Lactate, mmol/L 2.3 (0.7–10) 6 (2–19)

White cell count, 109/L 9 (0.9–38.9) 11.6 (4.4–44.3)

Platelets, 109/L 135 (22–579) 181 (46–371)

Immunosuppressed 2 2

APACHE = Acute Physiology and Chronic Health Evaluation. SOFA = Sequential Organ Failure Assessment. * Includes one venopulmonary artery.

Table 3. Pre-extracorporeal membrane oxygenation (ECMO) mechanical ventilation measures for venovenous cases

Patient Ventilation

mode PaO2/FiO2 PaCo2 pHVentilation compliance PEEP Quadrants RV dysfunction Barotrauma iNO

2 PCV 57 99 mmHg 7.04 30 mL/cm H2O 20 cm H2O 4 Severe No Yes

3 PCV 47 70 mmHg 7.32 24 mL/cm H2O 18 cm H2O 4 Mild No Yes

4 VCV 60 69 mmHg 7.06 20 mL/cm H2O 20 cm H2O 3 Severe No Yes

5 PCV 40 106 mmHg 7.1 24 mL/cm H2O 20 cm H2O 4 Moderate No Yes

6 VCV 63 42 mmHg 7.42 33 mL/cm H2O 20 cm H2O 4 None Yes No

7 VCV 39 67 mmHg 7.24 19 mL/cm H2O 15 cm H2O 4 None No Yes

9 Hand 51 60 mmHg 7.21 (10 mL/cm H2O)† 15 cm H2O 4 Moderate No Yes

11 VCV 56 95 mmHg 6.8 30 mL/cm H2O 20 cm H2O 3 Severe No Yes

12 VCV 46 51 mmHg 7.24 15 mL/cm H2O 20 cm H2O 4 Severe Yes Yes

19* Hand 52 45 mmHg 7.20 (10 mL/cm H2O)† 20 cm H2O 4 Severe No Yes

21 VCV 58 45 mmHg 7.27 28 mL/cm H2O 20 cm H2O 4 Moderate No Yes




iNO = inhaled nitric oxide. PCV = pressure-controlled ventilation. PEEP = positive end-expiratory pressure. RV = right ventricular. VCV = volume-controlled ventilation. * Includes Patient 19, who required venoarterial ECMO because of severe myocarditis secondary to group A Streptococcus pneumonia. † In those receiving hand ventilation, compliance was estimated from the most recent ventilator settings immediately before hand ventilation was started.


ORIGINAL ARTICLES

Extracorporeal membrane oxygenation equipmentAt TPCH, there are four complete Jostra Rotaflow (Maquet,Hirrlingen, Germany) systems with a fifth emergency back-up system that does not have a heater system but whichcould use a cardiopulmonary bypass heater cooler. Thereare two CentriMag (Levitronix, Waltham, Mass, USA) sys-tems, which are designed as a short-term ventricular assistdevice (replacing the Abiomed AB5000 [Danvers, Mass,USA]), but can be used for ECMO by adding an oxygenatorto the circuit.

A Rotaflow centrifugal pump and Quadrox D oxygenator(Maquet, Hirrlingen, Germany) (Figure 1) were used for 28patients (30 runs). The Levitronix CentriMag system (Figure2) was used for two patients — Patient 15, for whom it wasintended as a right ventricular assist device, but whorequired the addition of an oxygenator shortly after inser-tion of the system, and Patient 25.

The main limitation of the Levitronix CentriMag system isthe cost of disposables. To the best of our knowledge, TPCHis the only site in Australia that has it available, but it is the

Figure 3. Use of the Fresenius 4008s ARrT plus machine connected into the ECMO circuit for extended daily dialysis or plasma exchange

A. ARrT plus dialysis machine. B. Tubing connected into post-pump circuit.

Figure 2. Levitronix CentriMag system

A. Levitronix control unit. B. Levitronix control unit. C. Deoxygenated blood from the patient. D. Oxygenated blood returning to the patient. E. Quadrox D oxygenator.

Figure 1. Jostra Rotaflow with Quadrox D oxygenator in a typical configuration

A. Emergency hand crank. B. Rotaflow pump. C. Quadrox D oxygenator. D. Heater unit. E. Control unit.


ORIGINAL ARTICLES

system of choice in many large cardiac centres and hasseveral features that are superior to the Rotaflow system.Other Australian and New Zealand ECMO centres use theRotaflow centrifugal pump and Quadrox D oxygenator.Plasmapheresis and slow low-efficiency dialysis were con-ducted by direct connection into the ECMO circuit using theFresenius ARrT plus (Figure 3). A percutaneously insertedvascular access catheter was required if the continuousrenal replacement machines were used.

Extracorporeal membrane oxygenation cannulationCardiac surgeons performed most VA cannulations. Inten-sive care physicians performed 11/13 VV cannulations, twoperipheral VA cannulations and placed the venous (access)

cannulae for three emergency VA cases. Cardiac surgeonsperformed the remainder. Nineteen of 33 cannulationswere performed in the ICU and the remainder in the OT.The preferred venous access cannula was changed to a25 Fr Medtronic multistage cannula (Minneapolis, Minn,USA) for VV and VA at case 14 because of higher flows andeasier insertion.

The sites and methods of cannulation are shown inTable 5, Figure 4 and Figure 5. For peripheral surgical VAcannulation, the preferred return configuration was an8 mm Dacron (Melbourne, Vic, Australia) graft anasta-mosed to the femoral or axillary artery with a 22 Fr Sarnscannula (Terumo Cardiovascular Systems Corporation,Ann Arbor, Mich, USA) placed in the graft (Figure 4).

Table 5. Method of cannulation and circuit configuration

Patient ECMO typeWhere

insertedAccess

site Return site Access type/size Return type/size

1 Peripheral VA ICU RFV LFA 23 Fr 8 mm graft + 22 Fr Sarns

2 Percutaneous peripheral VV ICU RFV LFV 23 Fr 21 Fr






8 Percutaneous peripheral VA ICU LFV RFA 19 Fr 17 Fr + 8.5 Fr

9 Percutaneous peripheral VV OT RFV LFV 23 Fr 19 Fr

10 Central VA ICU RA Aorta 36 Fr 22 Fr


12 Percutaneous peripheral VV ICU RFV LFV 23/17 Fr 23 Fr

13 Central V, peripheral A OT RA LFA 36 Fr 8 mm graft + 22 Fr Sarns

14 Peripheral VA OT RFV RAxA 25 Fr multistage 8 mm graft + 22 Fr Sarns

15 Peripheral VPa OT/OT RFV PA 21 Fr then 25 Fr multistage 8 mm graft + 22 Fr Sarns

16 Percutaneous then surgical peripheral VA

ICU/OT RFV LFA then RAxA 25 Fr multistage 19 Fr + 8.5 Fr then 8 mm graft + 22 Fr Sarns


18 Peripheral VA ICU LFV RAxA 25 Fr multistage 8 mm graft + 22 Fr Sarns


20 Peripheral VA OT/ICU RFV RAxA then LFA 25 Fr multistage 8 mm graft + 19 Fr Medtronic

21 Percutaneous peripheral VV ICU RFV LFV 25 Fr multistage 21 Fr multistage

22 Peripheral VA ICU LFV LVA 25 Fr multistage 8 mm graft + 22 Fr Sarns

23 Percutaneous peripheral VV ICU LFV RFV 25 Fr multistage 23 Fr

24 Percutaneous peripheral VV ICU LFV RFV 25 Fr multistage 23 Fr

25 Central VA OT RA Aorta 34 Fr 22 Fr

26 Peripheral VA OT LFV RFA 25 Fr multistage 8 mm graft + 22 Fr Sarns

27 Peripheral VA OT RA Aorta

28 Peripheral VA OT RFV LFA 25 Fr multistage 8 mm graft + 22 Fr Sarns

29 Peripheral VA OT RFV LFA 25 Fr multistage 8 mm graft + 22 Fr Sarns

30 Percutaneous peripheral VV ICU LFV RIJV 25 Fr multistage 21 Fr

ICU = intensive care unit. LFA = left femoral artery. LFV = left femoral vein. OT = operating theatre. RA = right atrium. RAxA= right axillary artery. RFV = right femoral vein. VA = venoarterial. VPa = venopulmonary artery. VV = venovenous.


ORIGINAL ARTICLES

Surgical sealant was applied tothe graft. A backflow cannulawas placed with all percutane-ous arterial cannulations butnot when a Dacron graft wasanastomosed to the artery.One patient had right atrium(RA) access and return via thefemoral artery because thenature of aortic anatomy andsurgery precluded prolongedaor t i c cannu la t ion . Onepatient had VPa configurationfor temporary right ventricularsupport using a femoralvenous access cannula and an8mm Dacron graft anastomo-sed to the pulmonary artery asthe return. Patient 9 had theaccess and return cannulaemisconnected such that thereturn cannula was in the iliacvein and the access cannula inthe RA. Surprisingly, this did not result in excessiverecirculation so was not changed. There was one failedpercutaneous arterial cannulation (Patient 18) due to achronically occluded superficial femoral artery, which pre-vented insertion of a backflow cannula. This was notrecognised on a limited preoperative ultrasound scan. Theartery was explored and repaired without complicationsand the arterial return cannula placed in the axillary artery.Patient 20 required emergent re-exploration of the axillary

return cannula site, repair of the axillary artery and accessrevised to the femoral artery. Patient 21 accidentallyreceived a 21 Fr multistage cannula as the return cannula,but as recirculation was not limited, flows were high andoxygenation was adequate, it was not revised. In Patient20, the access cannula, and in Patient 21, the returncannula, were initially placed across the tricuspid valvedespite echo guidance. Repositioning was required andthere were no adverse effects.

Figure 5. Cannula positions in femoro-femoral venovenous extracorporeal membrane oxygenation*

A. Tip of return cannula in the right atrium. Part of the distal tip of the cannula is radiolucent. B. Tip of access cannula in the inferior vena cava. C. 21 Fr return cannula. Tip of cannula will sit in the right atrium. D. 25 Fr multistage access cannula traversing femoral and iliac veins and inferior vena cava with tip sitting just below the diaphragm.

* Images are from 2 different patients.

Figure 4. Methods of configuration of venoarterial (VA) extracorporeal membane oxygenation (ECMO)

i. The return to the patient is via the axillary artery. This avoids median sternotomy and allows mostly antegrade flow in the aorta at the expense of a potentially technically difficult procedure and lower flows. A. Dacron graft anastomosed onto right axillary artery. B. 22 Fr Sarns cannula connected into ECMO circuit and graft. ii. The arterial access was placed percutaneously and requires an additional cannula to perfuse the leg. C.17 Fr Medtronic arterial cannula retrogradely perfusing the aorta. D. 8.5 Fr Arrow backflow cannula for leg perfusion. iii. Central VA ECMO with cannula in the right atrium and return cannula in the ascending aorta. This allows use of larger cannula, resulting in higher antegrade flows in the aorta and ensuring coronary and cerebral perfusion. E. Return cannula in ascending aorta. F. Access cannula in right atrium.


ORIGINAL ARTICLES

There was significant later morbidity from the returncannulae in VA ECMO. Morbidity included infection andlate wound dehiscence requiring repeat surgery, but therewere no permanent major complications, such as limbinjury or loss of function. Infection occurred when graftmaterial was left in situ and subsequent patch arterioplastywas required. There was one injury to the femoral veinrequiring exploration and repair with placement of thereturn cannula in the right internal jugular vein. Latecomplications included clotting on the cannula and in theRA and one major pulmonary embolism.

Weaning from extracorporeal membrane oxygenationPatients were weaned from VV ECMO by reducing thesweep gas when the patients could be adequately venti-lated on � 50% oxygen + � 10 cm H2O positive end-expiratory pressure + 6–8 mL/kg tidal volume with plateaupressure < 30 cm H2O and evidence of radiological improve-ment. Weaning from VA ECMO occurred when cardiacfunction was adequate on reduced flows, based on clinicaland echocardiographic assessment. Percutaneously insertedvenous cannulae were removed in the ICU using directpressure. Arterial cannulae were removed and the arteryrepaired in the OT or ICU.

Patients, morbidity, mortality and outcomesOutcomes and complications are shown in Table 6. Overall,our study describes a sample with a high risk of death. Themedian duration of ECMO was 7 days for VA ECMO and 15days for VV ECMO, median mechanical ventilation was 484hours (20 days) (range, 0–1403 hours), median ICU staywas 22 days (range, 0–60 days) and median total hospitalstay was 34 days (range, 2–67 days). Twenty-one of 30patients (70%) were weaned or bridged and 20 survivedhospital (67%). Patient 15 had the VPa system removed andreplaced by a long-term right ventricular assist device andlater died in ICU. The ICU and hospital mortality for VVECMO was 2/13 (15%) and for VA was 8/17 (47%). Thetwo patients who died in the VV group were in establishedmultiple organ failure at the time of ECMO insertion.Sequential Organ Failure Assessment (SOFA) scores werehigh and similar in the VA and VV groups. All patientsdischarged alive from acute care were alive after 180 days.All but two patients weaned from ECMO received apercutaneous tracheostomy after ECMO removal for respi-ratory failure to facilitate liberation from mechanical ventila-tion. In the VA ECMO group, two patients died of aorticthrombosis. This was due to inability to maintain aorticejection despite inotropes, due to extremely poor cardiac

Table 6. Outcomes and complications*

Venovenous ECMO (n = 13) Venoarterial ECMO (n = 17)

Median duration of ECMO in hours (range) 356 (52–645) 160 (0–514)

Median duration of ventilation in hours (range) 633 (63–1121) 322 (0–1403)

Median intensive care unit length of stay (range) 660 (63–1152) 411 (0–1430)

Weaned or bridged, no. (%) 11 (85) 10 (58)

Hospital survival, no. (%) 11 (85) 9 (53)

Median total hospital costs, $AUD (range) $156 201 ($13 265–$241 407) $145 103 ($27 224–$346 742)

Median peak lactate, mmol/L (range) 4 (1.5–16) 8 (0.5–18)

Median peak bilirubin, mmol/L (range) 36 (4–264) 41 (4–132)

Median peak creatinine, mol/L (range) 255 (61–630) 146 (57–606)

Median lowest platelet count, 109/L (range) 70 (12–187) 41 (12–325)

Dialysis, no. of patients 7 5

Inotropes, no. of patients 8 17

Vasopressors, no. of patients 10 17

Median no. of circuits used (range) 1 (1–2) 1 (1–2)

Median highest plasma free haemoglobin, mg/L (range) 76 (43–175) 69 (28–199)

Median packed cells transfused, units (range) 11 (4–53) 31 (8–191)

Bloodstream infection complicating ECMO, no. of patients

4 3

Cause of death Intracranial bleed (1); multiple organ failure (1)

Aortic thrombosis (2); septic multiple organ failure (3); bleeding (2); no neurological

recovery (1)

ECMO = extracorporeal membrane oxygenation. * This includes one venoarterial ECMO patient who died in the operating theatre.


ORIGINAL ARTICLES

function. We normally tried to ensure an arterial pulsepressure of greater than 15 mmHg. Neither of thesepatients were candidates for conversion to a ventricularassist device.

Of the patients requiring two ECMO runs, Patient 15required return to OT for operative site haemostasis andreplacement of the access cannula, and an oxygenator wasadded to the circuit for oxygenation and temperaturecontrol. Patient 16 had an accidental arterial decannulationduring a planned ECMO removal on transfer from the ICUbed to the OT table, and required reinsertion of ECMOsystem for rapidly developing haemodynamic instability.Patient 20 had preoperative and postoperative support.

Blood product use was identified as a marker of how wellthe ECMO run was proceeding and showed significantvariability. The median number of packed cells transfusedper person during ECMO was 19.5 units (range, 4–191),median number of units of fresh frozen plasma transfusedwas 4 (range, 0–121 units) and median number of units ofplatelets was 3 (range, 0–54 units). Total transfusion rangedfrom 0.4 units to 29 units of blood products per patient perday. Transfusion was lower in the VV group than in the VAECMO group despite longer times on ECMO in the VVgroup. Our ECMO work unit guideline did not have atransfusion trigger, but this has since been set at 70 g/L.Plasma and platelet use and target levels are determined bywhether the patients are bleeding, type of surgery andplanned procedures. Re-exploration for bleeding was com-mon among patients who required ECMO after cardiacsurgery (6/8). Five patients were diagnosed with heparin-induced thrombocytopenia. Recombinant factor VIIa wasgiven to six patients while on ECMO for refractory bleeding.

Significant morbidity occurred with sepsis from surgicalsites, intravenous lines and nosocomial pneumonia.

Resource usePatients 3, 12, 16 and 20 required two circuits; all remain-ing patients were managed on one circuit. The total TPCHacute care costs using the “Transition 2” costing systemwere available for first 25 patients and excludes patientswho underwent transplantation. These are shown in Table6. The median cost per patient for acute care at TPCH was$151 572 (range, $13 265–$346 742). This excludes costsbefore admission to TPCH and for subacute care. Theestimated cost for ECMO patients is $6500 per day in ICU.

Discussion

ECMO is a complex, high-resource, high-cost therapy forcardio-respiratory failure. The risks and complications of theadditional extracorporeal circuit must be weighed againstthe potentially detrimental effects of ongoing ventilator-

induced lung injury, refractory hypoxia and/or hypercapnia,and organ hypoperfusion, together with the potential forreversibility of the underlying cause.

It is clear that we are late adaptors of this therapy, as thefirst adult ECMO case was reported in 197226 and the firstAustralian case was performed in 1972 at St Vincent’sHospital, Sydney.27 However, apart from selective casereports, early studies showed no outcome benefit forECMO over conventional ventilation strategies for acuterespiratory distress syndrome (ARDS) with poor overallsurvival.28,29 To reduce equipment-related errors, a clinicalperfusionist was on-site for the first 10 cases. This was builtinto the budget. A specific budget was provided for trainingand education. The TPCH program guidelines were adaptedfrom an experienced centre25 and complied with guidelinesrecommended by ELSO30 which have been summarised byMacLaren et al.31

The ideal ECMO candidate has reversible cardiac orrespiratory disease with an expected recovery time of 2–3weeks and does not have established multiple organ failure.The H1N1 cohort could be considered the ideal patients forVV ECMO because of the lack of comorbidities, young ageand expected resolution over 3–4 weeks. However in thissample, five of nine patients with H1N1 were in multipleorgan failure at commencement of ECMO due to bacterialsuperinfection or the direct effects of H1N1. In the VAgroup, seven patients (41%) had had a cardiac arrest beforeECMO initiation. SOFA scores were high, consistent with aseverely ill group.

Our respiratory ECMO protocol at this stage is a salvageprotocol for patients for whom maximal medical therapyhas failed. A previous study suggested patients with ARDSwho have a PaO2 < 60 mmHg on FiO2 1.0 for over 1 hourhave a mortality of 88% (65/74 died).32 In comparison, theAPACHE III-J predicted risk of death for VV ECMO patientswas 45%. The observed mortality for VV ECMO patients inour small sample is 15%. This is similar to that reported bythe ECMO H1N1 ANZ investigators (25% inhospital mortal-ity)6 and lower than that reported in the CESAR trial, whichhad a lower illness severity inclusion criterion (lung injuryscore, > 3.5).5 The overall mortality for cases reported to theELSO registry for ECMO for respiratory failure in adults isabout 50%. A multicentre study, the EOLIA (ECMO torescue lung injury in severe ARDS) trial is ongoing (clinicaltri-als.gov/ct2/show/NCT01470703).

Few articles have described a risk of death using a widelyused ICU scoring system, as young people with pneumoniaand assuming a Glasgow Coma Scale score of 15 will nothave an extremely high risk of death. Also, patients opti-mally managed before ECMO will ideally have fewer non-pulmonary physiological disturbances when recorded by theAPACHE method. Lastly, the ECMO group represents a


ORIGINAL ARTICLES

highly selected subset referred from other tertiary ICUswhose conditions have deteriorated despite maximal ther-apy, and thus their risk of death will potentially be increas-ing (lead time bias). There are few ECMO risk-of-deathmodels in adults. A model described by Hemmila andcolleagues included age, sex, pH < 7.1, PaO2/FiO2 and dayson ventilation before ECMO.12

The VA ECMO protocol for cardiac with or withoutrespiratory failure is also a salvage protocol. Outcomes inthe VA group were worse than the VV group. In selectpatients, the axillary artery was used as the return site toprovide “pseudo central” ECMO to ensure cerebral andcardiac perfusion in patients with poor gas exchange orsignificant peripheral vascular disease.

The APACHE III risk of death is calculated in the first 24hours of admission. In a high-risk subset, the APACHE IIIsystem may underestimate risk of death among those inwhom ECMO is placed in the OT. As VA ECMO improvesblood pressure and oxygenation, estimated risk of deathwill be lowered. This is seen in the predicted mortality of0.04 and 0.1 for the patients who failed to separate frombypass and required ECMO after coronary artery bypassgrafting surgery. The inhospital and 180-day mortality inthis report was 47% for VA (including one VPa case) ECMO.This is consistent with ELSO data outcomes. It would beexpected that outcomes in this group will be heavilyinfluenced by case selection and use of VA ECMO aftercardiac arrest. VA ECMO resulted in the reduction of theuse of temporary ventricular assist devices and a revision ofventricular assist device protocols. The Levitronix CentriMagsystem offers significantly more flexibility than the previoussystems.

Bleeding, thrombosis and sepsis were common complica-tions as is widely reported in the literature. The bloodproduct use was high. The definition used was the totalamount of products released by the Australian Red CrossBlood Service, and therefore will be the maximum amountthat could have been used (includes not recorded, discardedand wasted products) and includes products used in the OT.There are many definitions of bleeding complications, andwe propose that it was more clinically important to includetotal blood product use, as this is rarely done in otherstudies. All complications are associated with increased riskof death and their impact is listed in detail in the ELSOreport. We are reviewing potential strategies to reducearterial (“return” in VA ECMO) morbidity.

Experts suggest incidence of ARDS requiring ECMO is 1–2 cases per 1 000 000 population.33 Expert recommendationis that a minimum of six cases per year (ELSO)34 or 12–15cases per year33 are required to maintain competency. Usingavailable evidence, a mandatory review of the programshould occur if total case numbers are below 12 per year,

the inhospital survival for VV ECMO is less than 50% or theinhospital survival for VA ECMO is less than 33%.

ConclusionIn summary, we have described strategies to manage thelearning curve for a commencing adult ECMO program,which has included basing the model of care on that usedby an experienced centre, defined policy and procedures, aspecific budget for training and education, use of simula-tion, multidisciplinary case review and onsite clinical per-fusionists for the first 10 cases. Risk models for ECMOpatients require further development.

Acknowledgements

We thank the Alfred ECMO service and perfusionists and ICUnursing staff at TPCH.

Competing interests

None declared.

Author details

Daniel V Mullany, Senior Staff Specialist, Adult Intensive Care Services1,2

Taressa N Bull, Clinical Research Nurse,1 and Clinical Nurse, Adult Intensive Care Services2

William Hunt, Senior Clinical Perfusionist, Department of Anaesthesia and Perfusion1,2

Kiran Shekar, Staff Specialist, Adult Intensive Care Services1,2

Bruce Thomson, Department of Cardiothoracic Surgery1,2

John F Fraser, Director,1 and Professor in Intensive Care Medicine2

Marc Ziegenfuss, Director, Adult Intensive Care Services1,2

1 Critical Care Research Group, University of Queensland, Brisbane, QLD, Australia.

2 The Prince Charles Hospital, Brisbane, QLD, Australia.Correspondence: [email protected]

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