a b s t r a c t

Background: Traumatic epidural hematoma (EDH) with the potential to displace the brain tissue and increase in- tracranial pressure (ICP), is a life-threatening condition that requires emergent intervention. In rare circum- stances, emergency physician may have to do skull trephination to reduce the ICP as a temporary measure. Specific aims: To evaluate emergency medicine (EM) residents’ comfort in performing emergency department (ED) burr holes and to assess their difficulties and evaluate comfort level before and after simulated EDH cases. Materials and methods: A 3D-printed skull, electrical and manual drills were used for the simulation. Subjective comfort level pre and post-procedure, as well as objective procedural skills and time to complete the drill, were recorded.

Results: Twenty EM residents participated in the simulation study. The median time to perforate through the skull was 4 s for the electric drill and 10 s for the manual drill. A comfort level of 5 and above was reported by 12 par- ticipants for the manual drill and by 17 participants for the electric drill. Six participants had mild and 2 partici- pants had moderate observed difficulty in handling the manual and electric drill. Most participants performed both procedures successfully with one attempt only. Three participants have an overall comfort level above 5 before the simulation and 13 participants had overall comfort level above 5 post-simulation.

Conclusion: The 3D-printed model assisted the ED burr hole simulation and the residents could perform the procedure with minimum difficulties.

(C) 2023 Published by Elsevier Inc.

1. Introduction

Epidural Hematoma (EDH), a life-threatening condition that re- quires emergent intervention, occurs in the setting of head trauma and can progress to a life-threatening situation with increased intracra- nial pressure (ICP) and displacement of the brain tissue [1]. The middle meningeal artery, located in the temporal region, is the source of bleed- ing in most cases, but EDH can arise from venous sources as well, partic- ularly in the setting of anticoagulant use. Other not-so-common locations of EDH accumulation are in the vertex or posterior fossa [2-5]. This life-threatening condition requires immediate intervention to remove the clotting blood, and stop the displacement of brain tissue. The typical treatment for this pathology is a procedure performed by a

* Corresponding author at: Professor of Emergency Medicine, Director of Research, NYMC, Metropolitan Hospital Center, 1901 First Avenue, New York, NY 10029, USA.

E-mail address: getawworku.hassen@nychhc.org (G.W. Hassen).

trained neurosurgeon involving a craniotomy and hematoma removal in the operating room [6]. In the rare circumstance where there is no neurosurgery specialty in the hospital or transferring the patient is im- possible for a variety of reasons including extremes of weather or disas- ter, performing an emergency department (ED) burr hole can be a lifesaving procedure [7-13]. There are reported anecdotes of such kinds of procedures:(http://www.tmc.edu/news/2017/10/the- craniotomy-crew/, https://www.acepnow.com/article/perform- emergency-burr-hole-procedure/).

Knowledge of anatomy with landmarks and repeated practices may decrease anxiety and increase comfort which may lead to better out- comes for the affected patients. Most ED physicians are not trained in this procedure. Current Training models using cadavers are very ex- pensive. An alternative way is simulating the procedure using an ana- tomically similar 3D-printed skull with an attempt to improvise the intracranial structures such as the brain tissue, dura mater, and the hematoma.

https://doi.org/10.1016/j.ajem.2023.06.032 0735-6757/(C) 2023 Published by Elsevier Inc.

1. Specific aims

To evaluate the level of emergency medicine resident’s comfort in performing emergency department burr hole and to assess the difficul- ties in handling the devices and their performance. In addition, time re- quired to perforate through the 3D-printed skull for manual and electric drill will be evaluated.

1. Materials and methods
   1. Creation and use of the Simulation model

Using the freely available software 3DSlicer (www.slicer.com, ver- sion 4.11) a skull image from CT scan of a patient without private health information was converted into a 3D printable format. With the soft- ware a two-part skull was created (Fig. 1A, C, D). The smaller part (a flap) served as fractured skull where the hematoma rests. The big part served as the remaining skull. Another 3D-printed brain was placed in- side the skull (Fig. 1B). The brain was printed using soft filament while the skull was printed using hard filament. The files were then printed on a MakerBot Replicator+3D Printer. Only the calvaria was used for this simulation study. The thickness of the skull was 1 cm.

Two different trepanation devices were used. A manual and electri- cal craniotomy device (Fig. 1E, G).

• 1. Participants and procedure

Residents from an emergency program were asked to participate re- gardless of their post-graduate year (PGY) level. After they agreed to participate, they were given a pre-simulation questionnaire asking their PGY level, experience with burr hole (live or video) and their com- fort if they were to perform the procedure at the time of the simulation. They were then asked to perform trephinations using the two devices on the 3D-printed calvaria. Their performance was videotaped and later evaluated for the time required and their manual dexterity in han- dling the devices and performing the procedure. After the procedure, they were given a post-simulation questionnaire asking about their comfort level in handling the devices and comfort performing the pro- cedure using each device, their preferences of devices as well as their overall comfort after the simulation if they were to perform emergency burr hole.

1. Results

A total of 20 residents participated. All twenty residents performed burr hole with electric drill and only 15 used manual drill. Five partici- pants were PGY I, eight participants were PGY II and seven participants were PGY III. Twelve participants had never performed the procedure and 8 had tried it in a Simulated settings. Only 7 participants had watched videos of ED burr hole prior.

The median time to perforate through the skull for the electric drill was 4 s and the median time to perforate through the skull for the man- ual drill was 10 s. Based on the corresponding median times 14 partici- pants performed the drill in less than 4 s minutes with the electrical drill and 8 participants performed the drill in less than 10 s with the manual drill.

Reported personal comfort level on a scale of 1-10 for manual drill revealed that 12 participants had comfort level of 5 and above and 7 participants had comfort level below 5. Reported personal comfort level for electric drill revealed that 17 participants had comfort level of 5 and above and 3 had comfort level below 5.

Observed comfort level and manual dexterity (difficulty handling the device and performing the procedure on a scale of 1-10 for manual drill was as follows: 6 participants had mild difficulty, 2 participants had moderate difficulty and 7 participants had no obvious difficulty. Ob- served comfort level and manual dexterity (difficulty handling the

device and performing the procedure on a scale of 1-10) for electrical drill was as follows: 6 participants had mild difficulty, 2 participants had moderate difficulty and 12 participants had no obvious difficulty.

Most participants performed both procedures successfully with one attempt only. One participant needed two attempts with the manual drill. Five participants needed more than one attempt to successfully perform the procedure with the electrical drill.

Three participants had overall comfort in performing ED burr hole procedure of 5 and above pre-simulation and 13 participants had a com- fort level of 5 and above post-simulation. Table 1A-F represent the results.

The two drills have different size bit leading to different hole size. The electric drill made a bigger hole (1.4 cm) than the manual drill (0.5 cm) (Fig. 1F, H).

1. Discussion

Epidural hematoma is a life-threatening condition that requires emergent intervention. In centers with neurosurgery capacity, the pa- tient will be taken to the operating room immediately. Early and appro- priately performed procedures on patients with epidural have favorable outcomes. The Royal College of Surgeons in UK recommends decom- pressive surgery to remove epidural hematomas within 4 h of clinical deterioration [14]. Seelig et al. demonstrated that surgeries within 4 h had 30% mortality when compared to those who had operation after 4 h (90% mortality) [15]. Bulters et al. reported a delayed Decompressive surgery when patients were transferred from another facility in con- trary to those who presented directly to their site [16]. One study de- scribed outcome improvement when the hematoma is evacuated within 70 min of traumatic epidural hematomas. In the aforementioned studies neurosurgeons performed the procedure. Untreated cases can progress to herniation and ultimately death. In hospitals without neuro- surgery service, such as ours, the transfer to a neurosurgery center requires coordination and transport. Depending on unforeseen cir- cumstances such as bad Weather condition or availability of ambu- lances, the transfer may take hours. In those circumstances and if the patient’s condition deteriorates, the ED provider may need to do the emergent burr hole at the bed side. Burr hole is not a common procedure in the ED and EPs are not well-trained or have limited ex- perience performing them. Training can be obtained on cadavers, an- imal models or high-fidelity simulators. These options are very expensive. We came across a model that was created to practice burr hole procedure. This model costs approximately $110 (https:// www.acepnow.com/article/emergency-department-trephination- burr-hole-for-epidural-hematoma/). We created a 3D-printed model to practice burr hole that is even cheaper and represents es- sential parts of the anatomy. We created skull and brain from an ac- tual patient’s CT scan. We printed the models separately using different filament types. The skull was printed using polylactic acid (PLA) filament and the brain was printed using soft filaments. The advantage is that the big skull part can be used repeatedly, saving material. Each roll of filament costs on average $20. From this roll 3-6 skulls can be printed depending the desired skull size (pediatrics or adult). One model will cost approximately $15.

The result of the simulation showed that the diameter of the hole from the electric drill was three times as big as that of from the manual drill. The burr hole from the electric drill is likely to relieve the clot better than that of the one from the manual drill. In terms of ease of operation of the devices, residents had little difficulty using the electric drill, while the manual drill posed difficulty in operating.

• 1. Limitation

The 3D-printed material may not be exactly the same as the skull strength and composition. There was no hematoma to drain, so the ef- fectiveness of the procedure could not be evaluated. It did not involve

Fig. 1. 3D-printed skull, manual and electrical drills, burr hole size.

1. 3D-printed skull.
2. 3D-printed brain.
3. 3D-printed skull with skull flap removed.
4. 3D-printed skull flap.
5. Manual drill.
6. Burr hole size from manual drill.
7. Electrical drill.
8. Burr hole size from electrical drill.

Table 1

Demographic and clinical data.

E. number of attempts to Successfully Perforate the Calvarium number of attempts

(continued on next page)

Table 1 (continued)

F. Overall Comfort Pre-and Post-simulation on a Scale of 1-10

skin, muscle and other soft tissue procedures. The consistency of PLA

filament is not the same as the that of the skull.

1. Conclusion

Emergency Department burr hole simulation demonstrated that res- idents could perform the procedure. This is a simulated scenario with- out the pressure and stress of real life cases. This comfort and fast performance time may not reflect the actual comfort and ease if it had to be performed in an actual case.

Declaration of Competing Interest

None.

Acknowledgement

We thank Aida Betsy White-Mendez and the Metropolitan Hospital Auxiliary service for helping acquire the 3D-printers.

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