An Innovative Inexpensive Portable Pulmonary Edema Intubation Simulator

This pulmonary edema intubation simulator is designed to instruct paramedics, medical students, emergency medicine residents, emergency medical services fellows, and attending physicians.

Acute pulmonary edema results in respiratory distress and may require endotracheal intubation. On occasion, pulmonary edema can result in copious amounts of pink, frothy sputum in the airway, complicating intubation by hindering the intubator's view. Although airway management skills are frequently taught in a simulation setting, the frothy sputum seen in acute pulmonary edema is not easily replicated. Several articles have been published in reference to simulation model development for difficult airway management due to emesis obscuring the view of the glottic opening.1,2 There is, however, a scarcity of literature describing pulmonary edema airway management simulator construction, with only one other model identified on our review of the literature, which utilized cadavers, baking soda, vinegar, and red food coloring.3In our simulation center, we teach a variety of learners who may be called upon to care for patients in acute pulmonary edema in their clinical practice, including medical students, residents from various specialties, practicing physicians and pre-hospital personnel. We wished to familiarize these trainees with the challenges associated with intubating patients with significant frothy secretions within the hypopharynx by developing a dynamic, realistic, portable and inexpensive model to simulate the airway manifestations associated with acute pulmonary edema.

By the end of the session, learners will be able to: 1. Discuss the pathophysiology of, and immediate stabilization management steps for, acute cardiogenic pulmonary edema. 2. List the indications, contraindications, and risks associated with intubating a patient with acute cardiogenic pulmonary edema. 3. Demonstrate effective communication and teamwork skills to manage the airway of a simulated patient in respiratory distress due to acute cardiogenic pulmonary edema. 4. Successfully and safely intubate a simulated patient with a difficult airway due to visual obstruction from frothy pulmonary edema secretions.

We adapted a previously owned commercial airway task trainer simulator using an aquarium pump, tubing, an air stone, and an endotracheal tube. Pulmonary edema solution was created with glycerin, dish soap, (distilled) water and simulated blood. The solution and air stone are placed in one of the simulator's lungs. Subsequently, turning on the aquarium air pump generates simulated pulmonary edema within the lung itself, which froths up and out of the trachea and into the hypopharynx, mimicking the gross pathophysiological process.Learners complete pre-reading assignments prior to attending a small group didactic-practical session. Following a brief case discussion, led by the instructor, about the management of a patient in respiratory distress due to acute pulmonary edema, learners transition to a hands-on experience intubating the pulmonary edema manikin with the use of direct and video laryngoscopy, aided by a large bore Yankauer for suction and a bougie. Depending on the training level of the learners, the instructor will use judgment and may elect to demonstrate intubating the manikin using video laryngoscopy before the learners attempt the procedure. The authors recommend that the instructor use video laryngoscopy for teaching purposes so that all learners can visualize the intubation techniques (Yankauer, bougie) in the context of copious pulmonary edema fluid obscuring the glottis and surrounding airway structures.The practical portion is dedicated solely to intubation, with one learner assuming the role of the intubator and another assuming the role of a respiratory therapist, while the other leaners observe and/or provide real-time feedback. Learners rotate through these aforementioned roles. To maintain efficiency of the simulation session and maximize the number of intubation attempts each learner receives, the session is designed to begin with a case discussion about the management of a patient with acute pulmonary edema up through the timepoint of successful intubation, followed by a practical portion where the learners perform multiple intubations on the innovative pulmonary edema airway management task trainer. During the practical portion, real-time constructive feedback is given to each learner. At the end of the simulation session, a debriefing is completed.This model can be used to address several ACGME Emergency Medicine Milestones,4 specifically Milestone 9 (General Approach to Procedures - PC9), Level 4 (Performs indicated procedures on any patients with challenging features [eg, poorly identifiable landmarks, at extremes of age or with comorbid conditions], and also Milestone 10 (Airway Management - PC10), Level 4 (Performs airway management in any circumstance taking steps to avoid potential complications). This model can also be used to address ACGME Emergency Medical Services Milestones,5 specifically "Procedures Performed in the Pre-hospital Environment - Patient Care," Level 4 (Performs indicated procedures on any patients, including those with challenging features (eg, poorly identifiable landmarks, at extremes of age or with co-morbid conditions).

At the conclusion of the session, verbal feedback is sought from each participant by the instructor: How helpful did you find this simulation experience for learning about airway management in patients with acute pulmonary edema? Did you find the pulmonary edema intubation model to be realistic? Following this simulation experience, how would you rate your personal confidence in terms of managing an airway complicated by acute pulmonary edema?

For under fifty dollars, we have been able to adapt one of our previously owned airway management task trainers to build a pulmonary edema intubation simulator. It has been used in a wide variety of settings for different learners, including medical students, residents, fellows and pre-hospital providers. Since the 2016-2017 academic year, two hundred and twenty-six emergency medicine residents (PGY1, PGY2, and PGY3) have successfully used our innovative pulmonary edema airway management task trainer. Qualitatively it has been well-received and felt to be realistic by both our learners and instructors based on verbal feedback received following the simulation sessions.

We are aware of only one prior report attempting to simulate the frothy sputum seen in acute pulmonary edema. Lipe, et al., described mixing baking soda, vinegar and red food coloring in a cadaver hypopharynx just prior to an intubation attempt.3 This combination creates a fizzy frothy solution that fills the hypopharynx and pushes proximally into the mouth. This model is limited by design, however, in that it was unable to mimic a true in vivo appearance of a continuous flow of pulmonary edema-like fluid from the glottic opening. We feel we were able to overcome this limitation and also believe it is important for the leaner to experience the challenges of intubation when faced with copious secretions originating from within the lower airways. Our model generates the froth from within the lung itself, and it migrates proximally, similar to the dynamic pathophysiological process that occurs in vivo. Since we did not compare these two techniques, it is unknown which is more realistic. Neither the Lipe cadaver model nor our manikin model has been validated in terms of the realistic nature of the simulated pulmonary edema fluid. This would be ripe for future investigation. Nonetheless, informal qualitative feedback from our learners and instructors has been positive.Resident use of our innovative dynamic pulmonary edema airway management task trainer has been incorporated into our Emergency Medicine residency and Emergency Medical Services fellowship Clinical Competency Committee discussions with respect to ACGME Milestone satisfaction. Our model addresses level 4 of Emergency Medicine Milestone 9 (General Approach to Procedures) and Milestone 10 (Airway Management). Additionally, level 4 of Emergency Medical Services Milestone 2 (Procedures Performed in the Pre-hospital Environment - Patient Care) is addressed. Incorporating successful intubation of the dynamic pulmonary edema airway management task trainer has provided the EM and EMS faculty with a more objective measure by which to score the aforementioned milestones during the mid-year and year-end Clinical Competency Committee meetings.Overall, this innovation has met our objectives well. We have added this model to our library of more complicated airway management scenarios, such as vomitus and aspiration. Our emergency medicine residency program hosts a version of the difficult airway course and includes this pulmonary edema simulation station as part of that course. The model is very portable, allowing us to transport it to different sites for use. It is inexpensive, costing less than $50 to construct. Finally, the design is readily adaptable to any standard airway training manikin that has a simulated hollow lung with a detachable connection to a conduit representing a bronchus, which has a direct connection with a simulated trachea into which an endotracheal tube can physically be passed.

Airway management, difficult airway, intubation, obstructed airway, pulmonary edema, video laryngoscopy, visual obstruction.