Abstract
Background
Extracorporeal membrane oxygenation (ECMO) is a modification of cardiopulmonary bypass that allows prolonged support of patients with severe respiratory or cardiac failure. ECMO indications arse rapidly evolving and there is growing interest in its use for cardiac arrest and cardiogenic shock. However, ECMO training programs are limited. Training of emergency medicine and critical care clinicians could expand the use of this lifesaving intervention. Our objective was to develop and evaluate an abbreviated ECMO course that can be taught to emergency and critical care physicians and nurses.
Methods
We developed a training model using Yorkshire swine (Sus scrofa), a procedure instruction checklist, a confidence assessment, and a knowledge assessment. Participants were assigned to teams of one emergency medicine or critical care physician and one nurse and completed an abbreviated 8‐hour ECMO course. An ECMO specialist trained participants on preparation of the ECMO circuit and oversaw vascular access and ECMO initiation. We used the instruction checklist to evaluate performance. Participants completed confidence and knowledge assessments before and after the course.
Results
Seventeen teams (34 clinicians) completed the abbreviated ECMO course. None had previously completed an ECMO certification course. Immediately following the course, all teams successfully primed and prepared the ECMO circuit. Fifteen teams (88%, 95% confidence interval [CI] = 64% to 99%) successfully initiated ECMO. Participants improved their knowledge (difference 21.2, 95% CI = 16.5 to 25.8) and confidence (difference 40.3, 95% CI = 35.6 to 45.0) scores after completing the course.
Conclusions
We developed an accelerated 1‐day ECMO course. Clinicians’ confidence and knowledge assessments improved and 88% of teams could successfully initiate venoarterial ECMO after the course.
Extracorporeal membrane oxygenation (ECMO) is a modification of cardiopulmonary bypass that allows prolonged support of patients with severe respiratory or cardiac failure. There is some variation in ECMO circuits, but the essential components are the same: large‐bore vascular cannulas, blood pump with control module, membrane oxygenator, and oxygen source. Venovenous (VV) ECMO replaces lung function in patients with respiratory failure by removing deoxygenated blood, oxygenating the blood via the membrane oxygenator, and returning the blood to a patient's central vein. Venoarterial (VA) ECMO replaces heart function in patients with heart failure by removing blood from a central vein and pumping it into a central artery. Veno‐arterial‐venous (VAV) ECMO supports both lung and heart function by removing blood from a vein, oxygenating the blood, and pumping the blood back into both a central artery and vein.
A randomized controlled trial published in 2009 demonstrated that referral to an ECMO‐capable center was an efficacious and cost‐effective strategy for patients with severe acute respiratory distress syndrome (ARDS). 1 In that same year, there was unprecedented use of ECMO for adults with respiratory failure secondary to H1N1 influenza. 2 These two factors have spurred a rapid increase in ECMO utilization and established it as a valuable therapy for severe ARDS. 3 Additionally, ECMO indications are rapidly evolving and there is now growing interest in its use for cardiac arrest, cardiotoxic xenobiotic overdose, and cardiogenic shock. 4 , 5 ECMO has been used in the prehospital environment for cardiac arrest; however, the efficacy and appropriate patient selection procedures remain unclear. 6 , 7 , 8 The United States military has placed combat casualties on ECMO prior to evacuation from the combat theater with a high survival rate. 9 , 10
Despite the expansion of ECMO use, the number of hospitals with ECMO capability and ECMO‐trained personnel is still limited. 11 , 12 Even fewer medical systems have the ability to provide immediate ECMO to prehospital, emergency department (ED), and intensive care unit cardiac arrest patients. Expansion of ECMO training may increase the use of this lifesaving intervention; however, current ECMO training programs are limited, frequently require travel of 3 to 5 days in duration, and can be cost‐prohibitive. 13 , 14 Within the U.S. military, some casualties have died while awaiting the arrival of the military ECMO team. 10 Expansion of this skill via an abbreviated ECMO training course may provide this lifesaving intervention to a greater number of patients in need of immediate therapy due to active or impending cardiac arrest. The objective of our study was to develop and evaluate an abbreviated (less than 8 hour) ECMO course that can be taught to emergency and critical care physicians and nurses.
METHODS
Study Design
We conducted a prospective controlled study evaluating the efficacy of an abbreviated ECMO training course to provide emergency and critical care nurses and physicians the skills necessary to initiate and maintain ECMO therapy as well as troubleshoot common ECMO complications using swine as a live animal model. The 59th Medical Wing (59th MDW) Institutional Review Board reviewed the human study protocol and approved the study as exempt. The study was also approved by the 59th MDW Clinical Investigations and Research Support (CIRS) Institutional Animal Care and Use Committee.
Study Setting and Population
We solicited volunteer students from San Antonio Military Medical Center (SAMMC), the Department of Defense's only Level I trauma center, via e‐mail, word of mouth, and presentations at department grand rounds. Personnel eligible for inclusion as students included attending emergency medicine physicians, third‐year emergency medicine residents (from a single 3‐year emergency medicine residency), critical care attending physicians, critical care fellowship physicians, emergency medicine nurses, and critical care nurses who had no previous formal ECMO training or experience performing ECMO cannulation.
The study was conducted in accordance with the regulations and guidelines of the Animal Welfare Act, the National Institutes of Health Guide for the Care and Use of Laboratory Animals, and the American Association for the Accreditation of Laboratory Animal Care. The animals were housed at the 59th Medical Wing/CIRS vivarium, where the study was conducted. The study was funded by the Congressionally Directed Medical Research Program (CDMRP) Joint Program Committee 6 (JPC‐6)/Combat Casualty Care Research Program.
Materials
The CARDIOHELP ECMO pump (Maquet Getinge Group CARDIOHELP‐I REF 70104‐8012) and circuit (Maquet HLS Set Advanced 7.0, HLS 7050 USA, 701052794) were used. Cannulation was performed using the Maquet arterial and venous cannulas (PAL 1523, PVS 1938, and PVL 2155).
Course Materials
The course was set up in a teach, train, test model in which the students first reviewed educational materials (1.5 hours), next received step‐by‐step instructor training on a live swine model (2–3 hours), and finally were tested on their ability to prime and prepare the circuit and place the live animal on ECMO utilizing the provided checklist (2 hours).
Educational materials were developed from the current 3‐day SAMMC ECMO course. Visual slides used for didactic lectures from the SAMMC ECMO course were condensed to the knowledge material necessary for participants to identify appropriate ECMO patient candidates, initiate ECMO therapy, maintain ECMO therapy, and troubleshoot common ECMO complications. Since the purpose of the course was to provide physicians and nurses with the ability to initiate ECMO therapy until the hospital ECMO team assumed care, knowledge materials that focused on the weaning of ECMO therapy and decannulation were not included. The lectures covered the following topics: ECMO indications and contraindications, ECMO physiology, ECMO patient management, ECMO cannulation strategies and cannula selection, and ECMO circuit management (routine and emergency). Following the development of condensed slides, the primary investigator recorded videos of the narrated lectures with visual slides and posted these videos on a secure network, accessible only to the research team.
Step‐by‐step instruction checklists were also developed from the current 3‐day SAMMC ECMO course. These checklists were developed to provide a stepwise guide to assist students in initiating ECMO and troubleshooting ECMO complications. ECMO instruction checklists were developed for the following tasks: set‐up and priming of the ECMO circuit, patient cannulation, and management of ECMO complications.
We performed three model development sessions prior to student enrollment to assist in ensuring lecture and checklist accuracy as well as improving instructor performance.
Student Lecture‐based Training
At the beginning of each abbreviated ECMO course one physician and one nurse arrived at the training laboratory and completed a survey to obtain baseline demographic information and their ECMO comfort level as well as a written assessment to determine their ECMO knowledge (Table 1 and Figure 1). Upon completion of the survey and pretest, each student was provided a laptop on which they watched each of the recorded audiovisual lectures.
Table 1.
Student Characteristics
| Variable |
Total Sample (n = 34) |
Physicians Only (n = 17) |
Nurses Only (n = 17) |
|---|---|---|---|
| Time in position (years) | |||
| <1 | 5 (15%) | 5 (29%) | 0 (0%) |
| 1–5 | 15 (44%) | 10 (59%) | 5 (29%) |
| 6–10 | 10 (29%) | 1 (6%) | 9 (53%) |
| >10 | 4 (12%) | 1 (6%) | 3 (18%) |
| Department | |||
| ED | 20 (59%) | 16 (94%) | 4 (24%) |
| ICU | 14 (41%) | 1 (6%) | 13 (76%) |
| Time in department (years) | |||
| <1 | 4 (12%) | 2 (12%) | 2 (12%) |
| 1–5 | 22 (65%) | 12 (71%) | 10 (59%) |
| 6–10 | 6 (18%) | 2 (12%) | 4 (24%) |
| >10 | 2 (6%) | 1 (6%) | 1 (6%) |
| Work experience caring for ECMO patient(s) | |||
| None | 20 (59%) | 8 (47%) | 12 (71%) |
| 1–10 hours | 7 (21%) | 5 (29%) | 2 (12%) |
| 11–35 hours | 4 (12%) | 3 (18%) | 1 (6%) |
| >36 hours | 3 (9%) | 1 (6%) | 2 (12%) |
| Formal ECMO training experience | |||
| None | 34 (100%) | 17 (100%) | 17 (100%) |
| Other training | |||
| Advanced trauma life support (mannequin lab) | 18 (53%) | 15 (88%) | 3 (18%) |
| Advanced trauma life support (animal lab) | 10 (29%) | 9 (53%) | 1 (6%) |
| Pediatric advanced life support | 28 (82%) | 16 (94%) | 12 (71%) |
| Neonatal resuscitation program | 19 (56%) | 15 (88%) | 4 (24%) |
| Emergency war surgery course | 5 (15%) | 2 (12%) | 3 (18%) |
| Swine procedure lab or research | 5 (15%) | 5 (29%) | 0 (0%) |
| Other emergency medicine procedure lab | 5 (15%) | 5 (29%) | 0 (0%) |
Values given are number (%).
ECMO = extracorporeal membrane oxygenation; ICU = intensive care unit.
Figure 1.
Flow chart of study procedures. ECMO = extracorporeal membrane oxygenation; VA = venoarterial; VAV = veno‐arterial‐venous.
Animal Preparation
We sought to provide training and validation using a live animal model given the inability to evaluate mortality and physiology using a mannequin model. Practicing ECMO procedures on human volunteers is impractical and unethical; therefore, due to the similarities between human and swine cardiopulmonary anatomy, we elected to use a total of 34 Yorkshire swine (Sus scrofa) weighing between 70 and 90 kilograms. Seventeen swine were used in the training phase of the course, and 17 were used in the testing phase. These swine were fasted overnight except for water ad lib. Prior to induction of anesthesia, all animals were sedated with ketamine at an intramuscular dose of 10 mg/kg, and endotracheal intubation was performed. Mechanical ventilation was commenced and adjusted to maintain the arterial partial pressure of carbon dioxide (PCO2) between 38 and 42 mm Hg using a volume‐limited, time‐cycled ventilator (Fabius GS anesthesia machine, Drager‐Siemens). Anesthesia was maintained throughout the procedure, in a range between 1 and 3.5% by a qualified surgical technician using isoflurane titrated in air oxygen to maintain sedation and a stable blood pressure.
An arterial line was placed in the carotid artery via micropuncture to monitor blood pressure (Drager Infinity HemoMed Pod) and an intravenous line was started in the ear for the administration of maintenance fluids (normal saline). Once all lines were placed, isoflurane was maintained between 1 and 2% to mitigate isoflurane‐induced hypotension and apnea; at this point, animals were allowed to acclimate and the blood pressure to stabilize (at least 10 minutes). Electrocardiogram electrodes were placed for continuous monitoring of heart rate and rhythm. Animal temperature was maintained between 37.5 and 40°C using heating adjuncts as needed.
The fraction of inspired oxygen (FiO2) was maintained at 0.40. Following animal stabilization, a baseline arterial blood gas (ABG) was collected to obtain measurements of oxygen saturation, PaO2, PaCO2, hemoglobin (Hb), pH, bicarbonate, base excess, and lactate (ABL 800 Flex blood gas analyzer, Radiometer America).
Student Hands‐on Training
Subjects were taken to the ECMO lab where the research team, consisting of an ECMO‐trained physician, an ECMO‐trained nurse, and nurse assistants, provided verbal and hands‐on instruction to the students as they assembled and primed the ECMO circuit and cannulated the femoral veins and one of the femoral arteries. The ECMO students were reminded to use the previously developed written instructions in a stepwise fashion throughout this process. For the initial training and testing team, we started the swine on VV ECMO and then transition to V‐VA ECMO; however, following the initial team (two swine), we determined that the high propensity of swine to develop cardiac dysrhythmias made initiation of VA ECMO followed by transition to VAV ECMO more advantageous and was performed for the following 16 teams (32 animals).
Cannulation was accomplished using percutaneous Seldinger technique aided by ultrasound. Placement of the guidewire was verified by the cannulating physician via fluoroscopy before placing the appropriate cannula. Following appropriate wire placement confirmation, heparin was administered intravenously. Serial dilations of one of the femoral veins was performed using both the Maquet percutaneous insertion kit (12Fr.‐18Fr.; PIK 150‐USA) and the Avalon Elite vascular access kit (20Fr.; #12210). A 21‐French venous cannula (Maquet venous HLS cannulae/PVL 2155 21Fr.) was placed. Serial dilations of a femoral artery were performed up to 14 French, using the Maquet percutaneous insertion kit. A 15‐French arterial cannula (Maquet arterial HLS cannulae/PAL 1523 15Fr.). Cannulas were deaired and attached to the ECMO circuit. The cannulas were sutured into place for stabilization.
Following confirmation of successful VA ECMO initiation and swine stabilization, cannulation of the second femoral vein was accomplished using percutaneous Seldinger technique aided by ultrasound. Following placement of the guide wire, verification of cannulation of the appropriate vessel was verified by the cannulating physician via fluoroscopy. Serial dilations of the second femoral vein was performed using the Maquet percutaneous insertion kit up to 18‐Fr. A 19‐Fr. arterial cannula (Maquet arterial HLS cannulae/PAS 1923 19Fr.). The cannula was then deaired and a clamp was placed to ensure there was no entrainment of air or leaking of blood from the cannula. To initiate VAV ECMO, the arterial line flowing out of the ECMO circuit was clamped and cut. A Y‐connector (NovoSci, 3/8 in. × 3/8 in. × 3.8 in./C330S) was placed allowing the oxygenated blood from the ECMO circuit to be diverted into the 15‐Fr. arterial cannula and the 19‐Fr. venous cannula. Flow regulator clamps were placed on the tubing of the 19‐Fr.femoral vein cannula, allowing the ECMO participants to regulate the blood flow from the Cardiohelp between the arterial and venous system to ensure adequate blood pressure and oxygenation.
Following confirmation of successful VAV ECMO initiation and swine stabilization, the students were provided with hands‐on training on how to identify and correct the following common ECMO complications: loss of electrical power, access insufficiency (often referred to as “chatter”), air in the ECMO circuit, and loss of circuit integrity (i.e., a hole in the tubing).
Training Validation and Testing
Upon completion of the hands‐on training, the students were provided with all of the supplies necessary to prime and prepare the circuit, access and cannulate the required blood vessels, initiate and maintain ECMO therapy, and troubleshoot the common complications.
Two research assistants independently observed the students to evaluate and document performance and time to completion of each of the major tasks taught during the hands‐on training. Any difference in documented information between the research assistants were clarified via consensus; if there was no consensus, the primary investigator made the ultimate determination.
In the event that the students were unsuccessful in initiating ECMO therapy, an ECMO specialist would intervene and initiate ECMO. Failed ECMO initiation was documented and the students then proceeded to the following phase of study.
After initiation of ECMO, the students were asked to leave the room. While the students were out of the room, the research team induced a common complication. The students were then called back into the room and instructed to assess the patient and the Cardiohelp system, state what complication they encountered, and perform the necessary steps to correct the problem. This scenario was repeated for each of the following complications: loss of electrical power, excessive blood flow turbulence (“chatter”), diagnosis and removal of air from the venous side of the circuit, diagnosis and removal of air from the arterial side of the circuit, and loss of circuit integrity. Two research assistants independently observed the students to evaluate and document their performance and a lab timer kept track of how long it took to resolve each issue and resume ECMO therapy.
Following the troubleshooting phase, all questions and concerns were addressed with the students prior to completing the posttraining knowledge and comfort level assessment. After completion of the troubleshooting phase of both the training and the testing portions of the study, the swine were euthanized (IV pentobarbital, 100 mg/kg) under veterinary guidance in accordance with the American Veterinary Medical Association Panel on Euthanasia guidelines.
Measurements
The central premise of this study was to evaluate an abbreviated ECMO training course, evaluating competency following course completion. The success of each team in completing the tasks of initiating ECMO and troubleshooting the ECMO complications were compared.
In addition, the students’ comfort and knowledge were assessed with a survey and an assessment immediately before and after the ECMO training course. Descriptive summaries of participant demographics and backgrounds were conducted. The confidence assessment consisted of 10 items that described necessary steps to initiate and maintain ECMO. Students were asked to rate their confidence and experience level for each item on a scale from 0 (“no experience”) to 5 (“expert”). The knowledge assessment consisted of 20 questions (multiple choice and true/false) about ECMO procedures, indications, complications, and troubleshooting. ABGs to include electrolytes were collected at each blood draw (at baseline, immediately post‐ECMO initiation, and at study completion) with blood obtained from the carotid artery and/or the ECMO circuit.
Data Analysis
We reported categorical variables as frequencies and percentages and continuous variables as means with standard deviations. The primary endpoint was a binary outcome (successful ECMO initiation, yes vs. no). Other variables of interest include successful priming and preparation of the ECMO circuit (yes vs. no), preparation time (from start of lab to completion of circuit preparation), procedure time (from start of lab to completion of cannulation procedure), and lab time (from start of lab to completion of lab).
Swine characteristics and physiology were reported but not analyzed for comparisons. We evaluated inter‐rater agreement on the procedure instruction checklist using percent agreement over all items and teams (calculated as number of items in agreement across all teams divided by the total number of items across all teams) and Cronbach's alpha as a measure of internal consistency for the 10‐item confidence assessment. Scores from each item on the confidence assessment were summed and a percentage score was calculated out of the 50 possible points. We also calculated the proportion of students who rated themselves as “competent” (a score of 3) or better on each item. For the knowledge assessment, we calculated the percentage of correct answers (out of 20 items). Analysis of these secondary outcomes included paired t‐tests (for continuous variables) and McNemar tests (for nominal variables) comparing pretraining scores to posttraining scores to assess improvements on the confidence and knowledge assessments.
Power Analysis
A precision analysis was performed a priori and determined that a sample size of 17 teams (two clinicians per animal) could produce a 95% confidence interval (CI) of 90% to 100% with the assumption of 99.9% success rate in ECMO initiation. Analyses were performed using SAS v9.4 (SAS Institute, Inc.). Statistical tests are two‐sided with a significance level of 5%.
RESULTS
Characteristics of Study Subjects
A total of 34 clinicians (17 teams) completed the ECMO course including 11 attending emergency medicine physicians, five third‐year emergency medicine residents, and one pulmonary critical care fellow. Most physicians (88%) had been in their current position for 5 years or fewer. Most students had no experience caring for a patient on ECMO and none had ever completed formal ECMO training prior to this course (Table 1).
Primary Outcome
All 17 teams successfully primed and prepared the ECMO circuit (Table 2). One team did not use a lab timer; the remaining 16 teams prepared the circuit with a mean time of 31 ± 6 minutes (95% CI = 28 to 35 minutes). Fifteen of the 17 teams (88%, 95% CI = 64% to 99%) could complete the cannulation procedure (mean time from start of the lab: 59 ± 25 minutes; 95% CI = 45 to 74 minutes). Two teams were unable to initiate ECMO due to the students causing an arterial laceration during the cannulation process. One team successfully initiated VA ECMO but lacerated the second femoral vein and was unable to transition to VAV ECMO. The mean total lab time (from start to finish) was 145 ± 23 minutes (95% CI = 121 to 163 minutes).
Table 2.
Team Characteristics and Results of ECMO Simulation
| Team ID | Time in Position (Years) | Department | Time in Department (Years) | Work Experience With ECMO Patients (Hours) | Successfully Primed ECMO Circuit? | Time to Prime Circuit (Minutes) | Successfully Initiated VA ECMO? | Successfully Transitioned to VAV ECMO? | Time to ECMO Initiation (Minutes) | Total Lab Time (Minutes) | Notes | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PHYS | RN | PHYS | RN | PHYS | RN | PHYS | RN | ||||||||
| 1 | <1 (A) | 8 | ED | ICU | 3 | 8 | 0 | 1–10 | Yes | ‐ | Yes (VV) | Yes | — | — | Did not use timer |
| 2 | 3 (R) | 9 | ED | ICU | 3 | 5 | 11‐35 | 0 | Yes | 27 | Yes | Yes | 64 | 147 | |
| 3 | <1 (A) | 3 | ED | ICU | 3.3 | 11 | 1‐10 | 0 | Yes | 43 | Yes | Yes | 86 | 163 | |
| 4 | 2 (A) | 5 | ED | ICU | 5 | 4 | 0 | ≥36 | Yes | 35 | No | — | — | — | Fatal arterial laceration |
| 5 | 5 (A) | 4 | ED | ED | 8 | <1 | 0 | 0 | Yes | 37 | Yes | Yes | 125 | 185 | |
| 6 | 11 (A) | 8 | ED | ICU | 14 | 5 | 0 | 0 | Yes | 30 | Yes | Yes | 72 | 167 | |
| 7 | <1 (A) | 5 | ED | ICU | <1 | 4 | 1‐10 | 0 | Yes | 43 | No | — | — | — | Fatal arterial laceration |
| 8 | 3 (R) | 6 | ED | ICU | 3 | 3 | 1‐10 | 0 | Yes | 26 | Yes | Yes | 37 | 117 | |
| 9 | 2 (A) | 1 | ED | ICU | 6 | <1 | 0 | 0 | Yes | 29 | Yes | Yes | 61 | 147 | |
| 10 | 2 (A) | 12 | ED | ICU | 5 | 6 | 0 | ≥36 | Yes | 32 | Yes | Yes | 37 | 121 | |
| 11 | 2.5 (R) | 10 | ED | ICU | 2.5 | 5 | 1–10 | 0 | Yes | 28 | Yes | Yes | 51 | 135 | |
| 12 | 1 (A) | 9 | ED | ED | 4 | 9 | 0 | 0 | Yes | 33 | Yes | Yes | 54 | 157 | |
| 13 | <1 (F) | 13 | ICU | ICU | <1 | 10 | ≥36 | 0 | Yes | 35 | Yes | Yes | 49 | 158 | |
| 14 | 3 (R) | 9 | ED | ICU | 3 | 4 | 0 | 0 | Yes | 24 | Yes | Yes | 39 | 119 | |
| 15 | <1 (A) | 6 | ED | ICU | 4 | 3 | 11–35 | 11–35 | Yes | 31 | Yes | Yes | 81 | 172 | |
| 16 | 7 (A) | 4 | ED | ED | 1 | 4 | 1–10 | 1–10 | Yes | 25 | Yes | No | 40 | 141 | Lacerated femoral vein in transition |
| 17 | 3 (R) | 6 | ED | ED | 3 | 2 | 11–35 | 0 | Yes | 24 | Yes | Yes | 33 | 107 | |
A = attending; ECMO = extracorporeal membrane oxygenation; F = fellow; ICU = intensive care unit; PHYS = physician; R = resident; RN = registered nurse; VA = venoarterial; VAV = veno‐arterial‐venous; VV = venovenous.
Secondary Outcomes
The procedure validation checklist had 92% inter‐rater agreement across all items and teams and the confidence assessment showed good reliability (Cronbach's alpha = 0.90). All students showed an increase in confidence in completing ECMO tasks after the course. On average, their overall confidence scores improved from pretest (17.3 ± 10.8) to posttest (57.6 ± 18.1; mean difference = 40.3, 95% CI = 35.6 to 45.0). The proportion of students rating themselves as “competent” or better significantly improved for each item on the confidence assessment after the accelerated course (Table 3); these postcourse competency rates ranged from 47% (initiation of ECMO in a critical patient in a deployed setting) to 85% (initiation of IV anticoagulation). Nearly all students (33/34, 97%) improved their knowledge assessment scores after completing the course. Their overall knowledge assessment scores improved from pretest (64.7 ± 11.1) to posttest (85.9 ± 8.7; mean difference = 21.2, 95% CI = 16.5 to 25.8).
Table 3.
Proportion of Students Rating Themselves as “Competent” or Better on the Confidence Assessment
| Question | Pretest | Posttest |
Percent Difference/ Increase (95% CI) |
|---|---|---|---|
| 1. Determining which patients would benefit from ECMO | 6 (18%) | 21 (62%) | 44% (27%–62%) |
| 2. Initiation of IV anticoagulation | 18 (53%) | 29 (85%) | 32% (16%–49%) |
| 3. Placement of percutaneous cannula using Seldinger technique | 13 (38%) | 21 (62%) | 24% (9%–39%) |
| 4. Preparing cannulas for connection to ECMO circuit | 0 (0%) | 23 (68%) | 68% (51%–84%) |
| 5. Connecting patient to ECMO circuit | 0 (0%) | 21 (62%) | 62% (45%–79%) |
| 6. Securing cannulas | 5 (15%) | 24 (71%) | 56% (36%–75%) |
| 7. Achieving respiratory and hemodynamic goals | 12 (35%) | 27 (79%) | 44% (25%–64%) |
| 8. Maintaining ECMO during patient transport | 0 (0%) | 17 (50%) | 50% (32%–68%) |
| 9. Troubleshooting and managing issues with circuit/equipment | 0 (0%) | 19 (56%) | 56% (38%–73%) |
| 10. Initiation of ECMO in a critical patient in a deployed setting | 0 (0%) | 16 (47%) | 47% (29%–65%) |
Values given are number (percentages) out of n = 34.
On the assessment, “competent” is defined as “able to mostly recognize and complete the skillset or problem using my own judgment and able to achieve most tasks without additional input.”
ECMO = extracorporeal membrane oxygenation.
All 15 teams who successfully initiated ECMO could troubleshoot ECMO complications (Table 4). These complications included loss of circuit integrity, loss of power, venous air, arterial air, and access insufficiency. In those 15 animals successfully placed on ECMO, ABG values, and vital signs remained stable (Table 5).
Table 4.
Results of Troubleshooting Complications
| Complication | Teams Successful | Time to Troubleshoot Complications |
|---|---|---|
| Loss of circuit integrity | 15 (88%) | 5:00 (2:47–5:46) |
| Loss of power | 15 (88%) | 3:26 (2:42–3:43) |
| Venous air | 15 (88%) | 4:30 (2:34–5:44) |
| Arterial air | 15 (88%) | 4:19 (3:23–5:52) |
| Chatter/excessive blood flow turbulence | 15 (88%) | 1:08 (1:03–2:49) |
Values given are n (percentages out of n = 17) or median time in minutes:seconds (interquartile range).
ECMO = extracorporeal membrane oxygenation.
Table 5.
ABGs and Vitals for Swine at Baseline, ECMO Initiation, and End of Lab
| Variable | Baseline | ECMO Initiation | End of Lab |
|---|---|---|---|
| ABGs | |||
| pH | 7.47 (7.44 to 7.49) | 7.51 (7.47 to 7.55) | 7.32 (7.23 to 7.41) |
| pH* | 7.46 (7.43 to 7.48) | 7.51 (7.47 to 7.55) | 7.33 (7.24 to 7.42) |
| pCO2 | 41.58 (39.42 to 43.74) | 35.45 (31.68 to 39.22) | 45.84 (40.68 to 51.00) |
| pCO2 * | 42.97 (40.47 to 45.47) | 35.92 (31.96 to 39.88) | 45.04 (39.80 to 50.29) |
| pO2 | 206.77 (160.33 to 253.21) | 219.35 (159.61 to 279.09) | 254.32 (141.65 to 366.98) |
| pO2 * | 210.41 (164.26 to 256.56) | 220.58 (161.14 to 280.02) | 251.92 (140.87 to 362.96) |
| cK+ | 3.86 (3.63 to 4.10) | 3.93 (3.74 to 4.11) | 4.33 (3.64 to 5.03) |
| cNa+ | 140.94 (139.66 to 142.22) | 139.40 (138.03 to 140.77) | 140.33 (138.87 to 141.80) |
| cCa2+ | 1.25 (1.21 to 1.29) | 1.23 (1.18 to 1.28) | 2.06 (0.29 to 3.83) |
| cCl– | 103.35 (102.13 to 104.57) | 104.27 (102.69 to 105.84) | 107.17 (104.94 to 109.40) |
| cGLu | 73.82 (63.54 to 84.10) | 74.00 (65.24 to 82.76) | 91.58 (66.74 to 116.42) |
| cLac | 1.24 (1.04 to 1.43) | 2.21 (1.75 to 2.66) | 4.57 (2.84 to 6.30) |
| p50e | 24.94 (24.30 to 25.58) | 23.61 (22.56 to 24.65) | 29.13 (26.33 to 31.92) |
| cBase(Ecf)c | 5.79 (4.60 to 6.99) | 4.86 (3.55 to 6.17) | −1.72 (−6.18 to 2.75) |
| cHCO3‐(P,st)e | 29.62 (28.49 to 30.75) | 29.32 (28.09 to 30.55) | 22.78 (18.92 to 26.63) |
| tHb | 9.41 (8.89 to 9.93) | 9.15 (8.61 to 9.68) | 10.94 (10.14 to 11.74) |
| O2Hb | 96.63 (96.10 to 97.16) | 96.31 (95.34 to 97.28) | 94.06 (90.88 to 97.23) |
| COHb | 0.91 (0.41 to 1.41) | 1.17 (0.34 to 1.99) | 2.62 (−0.56 to 5.80) |
| MetHb | 1.14 (0.79 to 1.50) | 1.21 (0.79 to 1.63) | 1.16 (0.64 to 1.69) |
| O2Ct | 12.45 (11.45 to 13.44) | 12.44 (10.83 to 14.05) | 13.70 (12.86 to 14.54) |
| Vitals | |||
| HR | 88.65 (83.05 to 94.24) | 106.60 (90.19 to 123.01) | 111.21 (95.70 to 126.73) |
| SBP | 85.71 (77.82 to 93.59) | 84.73 (75.39 to 94.08) | 66.38 (54.16 to 78.60) |
| DBP | 54.82 (48.21 to 61.44) | 59.33 (53.72 to 64.95) | 37.58 (31.14 to 44.03) |
| SPO2 | 98.76 (97.70 to 99.83) | 98.27 (96.41 to 100.12) | 94.77 (91.39 to 98.14) |
| Temp | 37.56 (37.26 to 37.87) | 37.56 (37.17 to 37.94) | 36.88 (36.40 to 37.36) |
| RR | 12.24 (10.54 to 13.93) | 12.33 (10.35 to 14.32) | 10.79 (9.77 to 11.80) |
| ECO2 | 43.88 (42.20 to 45.57) | 37.60 (32.94 to 42.26) | 37.50 (30.22 to 44.78) |
| Pven | — | −36.77 (−48.14 to −25.40) | −99.55 (−129.80 to −69.30) |
| Part | — | 168.31 (143.81 to 192.81) | 115.09 (99.50 to 130.68) |
| Pint | — | 180.58 (153.93 to 207.24) | 119.45 (92.67 to 146.24) |
| RPM | — | 2685.00 (2545.98 to 2824.02) | 2869.09 (2668.77 to 3069.41) |
| LPM | — | 180.62 (−204.81 to 566.06) | 24.82 (−23.49 to 73.13) |
Values given are mean (95% CI).
ABG = arterial blood gases; DBP = diastolic blood pressure; ECO2 = carbon dioxide; HR = heart rate; LPM = liters per minute; Part = pressure after oxygenator; PCO2 = partial pressure of carbon dioxide; Pint = pressure before oxygenator; Pven = negative pressure in venous line; RPM = revolutions per minute; RR = respiratory rate; SBP = systolic blood pressure; SPO2 = pulse oximetry.
Values are temperature‐adjusted.
DISCUSSION
We found that following a brief 1‐day lecture and live‐tissue hands‐on ECMO training course, most emergency medicine and critical care physicians and nurses successfully initiated ECMO on a swine model. All student teams were successful at setting up and priming the ECMO circuit and troubleshooting common ECMO complications. To the best of our knowledge, our study is the first to evaluate the capability of a brief (less than 1 day) ECMO course to training emergency medicine and critical care physicians and nurses in the basics of initiating ECMO and troubleshooting ECMO complications. The expansion of similar training to ED and intensive care unit staff may allow for the initiation of lifesaving ECMO therapy for those patients with potentially reversible causes of cardiogenic shock and pulmonary failure, with the eventual transfer of care to an advanced ECMO team.
Our study also demonstrates a significant improvement in students’ confidence of comfort level. However, the level of confidence was below 80% in nine of the 10 categories measured (Table 3). In addition, two of the student teams were unable to initiate VA ECMO and one team was unable to transition from VA to VAV ECMO. While more confidence and a higher success rate is ideal for most procedures, ECMO is a therapy reserved for those patients who are unlikely to survive without it. In a case series of eight cardiopulmonary collapse patients placed on ECMO by emergency physicians and admitted to the hospital, five survived to hospital discharge neurologically intact. 4 Given the neurologically intact survival rate in cardiac arrest patients failing ACLS is near 0%, an 80% ECMO initiation success rate may result in clinically significant outcomes.
All three critical failures occurred due to laceration of a central vessel. In each of these cases, the physician created a false tract using the dilator or when placing the catheter. In each of these cases, this was due to advancing the wire and the dilator or catheter simultaneously. When this occurs, the wire fails to guide the dilator/catheter and instead the dilator/catheter can advance the wire to an undesired location damaging the central vessel. This is a known complication of large‐bore central vessel catheterization. When this occurs in a clinical setting, vessel repair may be performed by a vascular surgeon; however, fatalities have occurred. While wire control and avoiding the simultaneous advancement of the wire and dilator was emphasized during the hands‐on training, three of the 17 teams still made this error. While ECMO cannulation is commonly performed by vascular surgeons and other surgical specialties, Conrad et al. 15 demonstrated than nonsurgeons training in ECMO and with sufficient ECMO experience have similar success rates compared to surgeons. Further training and practice may improve skill performance and this will be emphasized and tested in our subsequent study.
A significant proportion of the U.S. population lacks geographic access to ECMO facilities and the majority of cardiac arrests are treated at facilities without ECMO. 16 While ECMO transport teams exist and the number of ECMO centers has increased significantly, some patients may benefit from the initiation of ECMO by emergency and critical care clinicians before transfer to advanced ECMO teams. Within U.S. military operations, the ability to deploy an ECMO team throughout global theater of operations exists. However, activating and transporting this team of highly trained individuals to the patient can take 30 or more hours. Those critically ill patients requiring ECMO are at high risk for clinically decompensating or dying during this critical time. 9 , 10 Therefore, ECMO training protocols similar to ours, in addition to skills maintenance and practice, may allow for the ability of physicians and nurses who do not currently perform ECMO to initiate this viable treatment modality in patients that may not otherwise survive.
Our plan is to train clinicians using ECMO simulation mannequins and then test them using a live swine model. Our expectation is that this lecture‐ and mannequin‐based course could be utilized in military and civilian hospitals throughout the country. Preparing emergency room clinicians to recognize the time‐sensitive need to for ECMO therapy and to initiate and maintain therapy until the ECMO specialty team arrives and assumes care could have potential lifesaving outcomes.
Our follow‐on study will evaluate the use of the same audiovisual lectures and checklists in combination with mannequin‐based hands‐on training instead of a live‐tissue training model. The mannequin will also permit the students to practice cannulation multiple times (something the live‐tissue model did not provide). We hypothesize that in increased practice will increase cannulation wire control, decrease damage to the central arteries and veins, and improve student confidence in performing this challenging procedure.
LIMITATIONS
Our study has several limitations. First, given the logistic and ethical issues of performing training and testing on humans, we used an animal model as a substitute; however, there are significant similarities in swine and human anatomy. While the femoral vessels in swine are more tortuous, this likely makes performing cannulation on swine more challenging than on humans. Extrapolation of our findings to other institutions may be limited given most institutions do not have live‐tissue training labs. Our follow‐on study will use lecture and mannequin‐based training with testing on live swine to determine if a mannequin‐based course is sufficient. Additionally, the testing of the students occurred immediately following the hands‐on training. It is unclear how long following the training the students would remain proficient and what skills maintenance training is required. However, the audiovisual lectures were intentionally developed with the plan to post them online for viewing by interested physicians and nurses as necessary. The hands‐on portion of the training took less than 2 hours and could be incorporated into graduate medical education or faculty education programs. Finally, our training was focused on training individuals to initiate ECMO and was not designed to prepare students to maintain and wean ECMO therapy since those are tasks that would likely be transitioned to an inpatient ECMO team at an advanced care hospital.
CONCLUSIONS
We developed an abbreviated 1‐day extracorporeal membrane oxygenation course that resulted in an improvement of emergency and critical care physicians’ and nurses’ confidence and knowledge assessments. Following the training, 88% of teams successfully initiated venoarterial extracorporeal membrane oxygenation therapy and 82% successfully initiated veno‐arterial‐venous extracorporeal membrane oxygenation.
AEM Education and Training 2020;4:347–358
Presented at the Military Health System Research Symposium, Kissimmee, FL, August 2019.
This work was funded by the Department of Defense (DOD), Joint Program Committee‐6 (JPC‐6)
The authors have no potential conflicts to disclose.
The views expressed are those of the authors and do not reflect the official views or policy of the Department of Defense or its components.
Author contributions: JKM—principal investigator, obtained funding, designed the study, developed the lectures, provided training to study participants, and drafted and edited the manuscript; RMP—edited and provided critical revision of the manuscript; JAP—assisted in study design and acquisition of data; MC—acquired data and edited the manuscript; AAA—assisted with study design, performed statistical analysis, and provided critical revision of the manuscript; CAP—acquired data and edited the manuscript; LKR—acquired data and edited the manuscript; RKN—assisted with the experimental design, provided training to study participants, and edited the manuscript; VB—assisted with experimental design and edited and provided critical revision of the manuscript; NK—edited and provided critical revision of the manuscript; and PM—ECMO subject matter expert that assisted with experimental design and edited and provided critical revision of the manuscript.
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