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Pediatric Extracorporeal Membrane Oxygenation (ECMO) Transport in a Developing Nation: A Single Center Experience

Martinez, Daniela*,†; Diaz, Rodrigo‡,§; Rufs, Jorge‡,§; Fajardo, Christian‡,¶; Valverde, Cristián†,‡; Salech, Felipe

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doi: 10.1097/MAT.0000000000001567
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Extracorporeal membrane oxygenation (ECMO) support requires skills that can only be found in specialized centers. The number of patients annually supported with ECMO is positively associated with the survival rate, so transport to a specialized center is recommended.1 Some patients are too ill to be transferred under conventional transport (mechanical ventilation/vasoactive drugs), so they must be transferred on ECMO. Cannulating the patient at the referring hospital and transporting on ECMO was first described by Bartlett et al.2; since then, a large number of ECMO transports have been described. Mobile ECMO for pediatric patients combines specificities of hemodynamic management of a low-weight patient with transportation’s technical issues, and currently, there is a paucity of reported data of indications, processes, and outcomes of pediatric ECMO transport[3]. To our knowledge, in Latin America, pediatric ECMO transport is only available in Brazil, Colombia, Mexico, and Chile, and no reports have been published. Our institution implemented Mobile ECMO in March 2007, and the first pediatric ECMO transport was carried out in July 2011.

We retrospectively reviewed our institutional database of all patients ≤18 years old who were transferred on mobile ECMO. The institutional review board approved the study.

Requests for mobile ECMO were initiated by the referring physician calling by phone to an ECMO-team pediatric intensivist to evaluate 1) the referral indication, 2) the eligibility to ECMO support according to ELSO Guidelines,4–6 and 3) the chance to improve the local management avoiding the use of ECMO when not necessary. Patients were eligible for respiratory ECMO if they had a severe, refractory, potentially reversible hypoxemic or hypercapnic respiratory failure and met any of the following criteria: oxygenation index >30, PaO2/FiO2 ratio less than 100 despite maximal medical therapy (prone positioning, fluid restriction, NO, neuromuscular blockade, high-frequency oscillatory ventilation [HFOV]), hypercapnia, and respiratory acidosis with pH <7.15 or plateau pressure >35 mmH2O despite optimized ventilator settings. For cardiac ECMO, patients were candidates with cardiogenic shock, hypotension with more than three vasoactive drugs and elevated lactate, refractory to medical management. Patients with known ECMO contraindications or a nonreversible disease were denied support, consistent with the ELSO guidelines.3,5,6 After the ECMO eligibility was confirmed, an on-call ECMO team consisting of a cardiothoracic surgeon, anesthetist, perfusionist, and an ICU nurse, with high training in cannulation and technical management of the ECMO system, were alerted. The team was available 24 h per day, 7 days per week, all year round. The time from the decision to go until the departure was between 30 and 90 min. The equipment and devices used for the transfer on ECMO are detailed in Table 1.

Table 1 -
Cannulation Material Extracorporeal Circuit Material Emergency Support Material
Vessel dilators 6-28 Fr
Opus by MC3
Insertion kit by Medtronic
Surgical venous cannula 8- 14 Fr, Biomedicus by Medtronic and/or percutaneous venous cannulas Biomedicus by Medtronic according to patient’s weight and two different sizes 1 Fr above and 1 Fr over. Face masks N° 1, 2 and 3, ET tubes N° 3-7.5.
Introducers 4 Fr and 5 Fr, radiofocus by terumo Surgical arterial cannula 8- 14 Fr, and/or percutaneous arterial cannulas 15-23 Fr according to patient´s weight and two different sizes (Medtronic) CPR material + emergency drugs.
2× micropuncture introducer set by Cook® 2× ECMO membrane lung and circuit by Maquet or by Eurosets Vascular arterial, venous catheters, connectors by arrow or terumo.
Connectors 1/4-1/4, 1/4-1/4 Luer, 3/8 × 3/8, 3/8 × 3/8 Luer, Y 1/4-1/4-1/4, Y 3/8 × 3/8-3/8 by Maquet or Eurosets or Medtronic Sterile priming solution
Saline solution, albumin 20%, ringer, could be replaced by blood to keep the hematocrit over 30%, mainly in patients ≤ 10 kg.
IV fluids, saline solution, ringer, albumin 20% and one RBC pack.
2× 0.035” Flex L × 260 cm vascular guidewires Radiofocus by Terumo Three-way stopcocks by terumo.
2× 0.035” × 180 cm angle vascular guidewires, Radiofocus by Terumo US special gel for centrifugal pump flowmeter by Maquet.
Gas connector for the ambulance or aircraft type Ohio.
Electrical adaptors and check the power supply at ambulance and aircraft.
Electrical and biomedical equipment
Oxygen tanks enough for the distance × 2. ICU portable monitor by Spacelab or Lifepak 15 by Physio Control 4 Syringe Infusion pumps by Terumo.
Jackson Rees ventilation circuit.
Transport ventilator by Hamilton®
ECMO centrifugal pump Rotaflow by Maquet or Cardiohelp. ECMO water heater by Maquet.
ECMO emergency manual drive, Hand-crank by Maquet. Portable ultrasound by Sonosite
Portable Ultrasound flowmeter by Transonic.
CPR, cardiopulmonary resuscitation; ECMO, Extracorporeal membrane oxygenation; ET, endotracheal; Fr, French; RBC, red blood cells.

At the referral hospital, ultrasonography was carried out by the cardiovascular anesthesiologist and surgeon and used to determine the ECMO mode and to guide cannulation. Veno-venous (VV) ECMO was implemented for respiratory indications without hemodynamic compromise, while peripheral veno-arterial (VA) ECMO was used for patients with cardiogenic shock, hemodynamic compromise, or due to technical difficulties in younger patients with respiratory failure. Before cannulation, patients received a bolus of unfractionated heparin of 5–10 IU/kg. The internal jugular vein was preferentially cannulated for double-lumen VV ECMO. For dual-site VV-ECMO, the right internal jugular and right femoral veins were the preferred access sites. The neck vessels were used for VA ECMO. The position of the cannulas was confirmed by x-ray before departure. The circuit was primed with blood if the patient’s weight was ≤10 kg or with saline solution in patients with higher weights. Once ECMO was established, patients were ventilated with rest settings: PEEP 10cmH2O, PIM 10cmH2O, Respiratory Rate 10×´. ROTAFLOW centrifugal pumps and PLS-i oxygenators (Maquet Cardiopulmonary, Hirrlingen, Germany) were used during transportation.

Between July 2011 and March 2020, 30 pediatric patients fulfilled ECMO transport criteria and were cannulated by our ECMO mobile team at the referral center. One patient died during cannulation. Twenty-nine patients were safely retrieved with no severe adverse events during transfer, except for one monitoring arterial line displacement without bleeding. There were no intra transport power failures or malfunctions. The patients were retrieved by ambulance (n = 17), fixed-wing aircraft (n = 11), and by helicopter (n = 2). The median distance of transport was 123.5 km, and the furthest referral hospital from where a patient was transported was 1,708 km. Population demographic variables, ECMO characteristics, and outcomes are described in Table 2. The most common indication for ECMO was a severe refractory respiratory failure (77%), and viral pneumonia was the most frequent etiology (n = 9). Twenty-one patients were connected to HFOV as a rescue therapy before ECMO, and 10 patients used iNO. The survived ECMO was 80% (24 out of 30 patients) and survival to discharge from hospital was 73% (22 out 30 patients). All patients discharged from the hospital are alive at the time of this review. The survival of these patients was compared with pediatric ECMO patients cannulated in our center in the same period. This group consisted of 55 patients, of whom three had a cardiac failure, four were extracorporeal cardiopulmonary resuscitation, four had septic shock, and forty-four had respiratory failure. The survived ECMO of the in-house ECMO group was 60% (33 out of 55 patients), with no significant difference with the mobile ECMO group (P = 0.4).

Table 2 -
Raw Number and Percentage OR Median (IQR)
Total 30
Age (years) 2 (0–10)
Male 21 (70%)
Weight (kg) 12.75 (6–26)
Body mass index (BMI) 14.1 (12.3–19.5)
ECMO indication
*Cardiac 6 (20%)
*Respiratory 24 (80%)
*Severity of illness (PIM2 score) 26.01 (18.5–68.5)
Diagnosis
 Pneumonia 13 (43%)
 Respiratory distress syndrome 5 (17%)
 Septic shock 3 (10%)
 Hantavirus cardiopulmonary syndrome 2 (7%)
 Myocarditis 2 (7%)
 Congenital cardiopathy 2 (7%)
 Meconium aspiration syndrome 1 (3%)
 Congenital diaphragmatic hernia 1 (3%)
 Atrial flutter 1 (3%)
Pre ECMO (respiratory indication)
*Mechanical ventilation before ECMO (days) 2.5 (1–4.5)
*PaO2/FiO2 52 (39–60)
*Oxygenation Index 37 (28–45)
*PaCO2 67 (49–113)
*CPR before ECMO 4 (*16%)
*pH 7.22 (7.025–7.35)
Pre ECMO (cardiac indication)
*Mechanical ventilation before ECMO (days) 1.5 (1–2)
*Lactate 19.8 (12–51.3)
*CPR before ECMO 3 (50%)
Mode of ECMO
*VV 12 (40%)
*VA 18 (60%)
Mode of transport:
*Ambulance 17 (56.6%)
*Fixed wings aircraft 11(36.6%)
*Helicopter 2 (6.7%)
*Time of transport (hours) 2.13 (0.95–2.4)
Median run distance (km) 123.5 (24–517)
Complication during transport
*Patient-related 1 (3.3%)
*ECMO-related 0
*Monitoring devices-related 1 (3.3%)
ECMO Outcomes
*Days of ECMO 10 (4–17)
*All-cause mortality 8 (27%)
*Survived ECMO 24 (80%)
*Survival to hospital discharge 22 (73%)
*16% of all patients with Respiratory indication for ECMO support.
50% of all patients with Cardiac indication for ECMO support.
CPR, cardiopulmonary resuscitation; ECMO, Extracorporeal membrane oxygenation; VA, veno-arterial; VV, Veno-venous.

To our knowledge, this is the first report of a pediatric mobile ECMO program in South America. Chile is a middle-income country located in the southwest region of South America characterized by geographic isolation determined by the Andes mountains and the Pacific Ocean. All the centers with pediatric ECMO are in Santiago (the biggest city). Therefore, patients from remote regions need to be transferred there. Despite these difficulties, the clinical outcomes of our mobile ECMO program, including survived ECMO, hospital discharge, and 1-year follow-up, are similar to those reported by other authors from high-income countries.3,7–9 In summary, we report that cannulation of pediatric patients at the referring center followed by transport to an experienced center on pediatric ECMO is feasible and safe when conducted by a highly skilled team, even in lower-income countries with geographic difficulties.

References

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2. Bartlett RH, Gazzaniga AB, Fong SW, Jefferies MR, Roohk HV, Haiduc N: Extracorporeal membrane oxygenator support for cardiopulmonary failure. Experience in 28 cases. J Thorac Cardiovasc Surg. 73: 375–386, 1977.
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