ResusTEE course and protocol
The study was approved by the Regional Ethical Committee.
ResusTEE course was attended by ten EPs (six specialists and four residents) with at least 1 year of experience in FoCUS. The course was composed of 2 hours of formal lectures and 8 hours of a hands-on clinical training. The lectures included the review of basic TEE principles, indications and contraindications for TEE, demonstration of probe insertion and the technique needed to acquire six views of a simplified TEE protocol and to identify, through video loops, anatomic structures as well as the most common pathologic findings.
The clinical training was performed in three cardiac surgery operating rooms with cardiovascular anesthesiologists, certified as tutors in adult transesophageal echocardiography by the European Association of Cardiovascular Imaging. Each operating room was equipped with an ultrasound system provided with a 7.0-MHz TEE probe: SONOS 5500 (Phillips Medical Systems, Bothell, WA), iE33 (Philips, Andover, MA) and EPIQ 7(Philips, Andover, MA).
The tutor guided the trainees to acquire the manual and interpretive skills needed for the insertion of the probe, acquisition, and interpretation of six different TEE views. The trainees inserted the probe in patients scheduled for elective cardiac surgery, already intubated, under general anesthesia. TEE is routinely performed in such patients for monitoring purposes and to check the result of surgery. Therefore, patients were not subjected to any additional risk due to the teaching procedure and, since the same TEE views were used also for clinical purposes, the training did not interfere with the surgery.
ResusTEE protocol was composed of six sequential views: mid-esophageal four-chamber (ME4CH) (Fig. 1a–Additional file 1: video 1a), mid-esophageal long axis (MELAX) (Fig. 1b–Additional file 2: video 1b), mid-esophageal two-chamber (ME2CH) (Fig. 1c–Additional file 3: video 1c), mid-esophageal bicaval view (MEbicaval) (Fig. 1d–Additional file 4: video 1d), transgastric short axis (TGSAX) (Fig. 1e–Additional file 5: video 1e) and aorta view (AOview) (Fig. 1f–Additional file 6: video 1f) (Additional file). This protocol differed from the one proposed by the American College of Emergency Physicians because of the addition of three views (ME2CH, MEbicaval and AOview) [12] and from the protocol proposed by the University of Pennsylvania due to the addition of two views (ME2CH and AOview) [15].
Skill assessment throughout the course
During the practical training, the trainees were monitored and the effective hours in which they handled the probe, the number of exams performed, and the type and number of inspected pathological findings were registered. Furthermore, at the end of the training period, an observer medical student registered the time needed to insert the probe and to acquire the six views of the protocol. One of the two anesthesiologists rated the skills of the trainees. The same assessment was repeated after 2 h of hands-on retraining, 12 weeks after the completion of the course, to evaluate skills retention over time.
The skill assessment consisted of a practical exam, by which the technique of probe insertion, acquisition and interpretation of the six different views (ME4CH, ME2CH, MELAX, MEbicaval, TGSAX, AOview) were evaluated and rated separately. The tutors used a rating system (from 1 to 5) as follows: 1 = inadequate, 2 = insufficient, 3 = sufficient, 4 = good and 5 = excellent.
The insertion of the probe was assessed considering the quickness time required for insertion and taking into account the possible need for help from the tutor, according to the following scale: 1 = insertion failed; 2 = insertion achieved only with substantial tutor’s intervention; 3 = insertion achieved in > 2 min; 4 = insertion achieved in > 1 and ≤ 2 min; 5 = insertion achieved in ≤ 1 min. The learner’s ability to acquire each of the 6 views was also assessed on the basis of a similar evaluation scale previously published taking into account quickness the time required to obtain the view and the amount of help needed by the learner to reach the target [16]. This scale has been adapted on the basis of the aforementioned 5 skill levels according to the following scheme: 1 = image acquisition failed; 2 = image achieved only after substantial tutor’s help; 3 = image achieved slowly but with small tutor instruction; 4 = image achieved slowly but without any tutor instruction; 5 = image obtained quickly and fluidly as part of a complete examination without any help from the tutor. To attribute the score, the tutor also took into account the objective difficulties encountered both by himself and by the learner, in clinical cases in which the acoustic window was suboptimal. Therefore, in these cases, a view was considered as adequately achieved if similar to the best obtainable by the certified tutor. Similarly, criteria to consider an adequately interpreted view (rating ≥ 3) were the confidence in the correct identification of all the anatomic structures and the completeness in the discussion of all the potential pathological conditions that could be identified by each view. In this regard, the tutor assigned a score ranking from 1 to 5 according to his personal experience and at his discretion.
Implementation of resusTEE performed by EPs in clinical practice
For 12 weeks, after the end of the course, we monitored the effective application of resusTEE performed by all the trainees in ED. Each one of the EPs trained in the course was involved in resuscitation in case of out-of-hospital cardiac arrest (OHCA) and the decision to perform a resusTEE in addition to FoCUS was decided by the resuscitation team leader. The FoCUS was already part of the standard management of OHCA in our ED and was always performed according to the European Resuscitation Council guidelines [1]. ResusTEE was performed by EPs, with the supervision of a cardiologist or an anesthesiologist, part of the resuscitation team, after patients’ intubation, using a dedicated ultrasound machine (Vivid S5 ultrasound multiprobe machine provided with a GE 6Tc-RS TEE Probe, GE Healthcare, Wauwatosa, WI, USA), available in the shock room 24 h a day, 7 days a week. The time from the patient’s arrival in the shock room to the successful probe insertion, the time needed to complete the TEE exam and the different views performed by EPs were recorded by a medical student. The resuscitation team leader completed a standardized form after having finished the clinical management. The form reported if resusTEE had led to a modification of the diagnosis made by FoCUS, when it suggested a shift of the site of chest compression during CPR, when it was used to guide vessel cannulations as well as for the interruption of CPR.
The results were presented as a percentage for dichotomous variables, as mean ± standard deviation for normally distributed variables. The analysis was conducted using Excel 15.30 (Office, Microsoft, United States of America).