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BRIEF REPORTS A Comparison of a Novel Cricothyrotomy Device with a Standard Surgical Cricothyrotomy Technique Cricothyrotomy is an important tool for airway management in the ED, as occasionally patients cannot be intubated by more routine, less invasive methods.1,2 In these cases, there is a need for a quick and efficient way to obtain a surgical airway.3 None of the existing devices for invasive airway management provides a reliable method to insert a cuffed endotracheal tube without a cumbersome kit, guidewires, or large surgical packages with multiple instruments.4–6 A recently proposed solution to this issue is a technique described by Brofeldt et al., which consists of a simple four-step maneuver. This technique has minimal reliance on tools other than a scalpel and tracheal hook.7 One advantage of this method is that these tools are simple and readily available and could routinely be carried in one’s pocket. However, Brofeldt et al.’s rapid four-step technique
(RFST) has been shown to occasionally cause injury, because it requires traction with a single hook on the anterior aspect (i.e., the thinnest part) of the cricoid cartilage.8–10 The new device described in this report, which is used in a fashion similar to that of the RFST, provides an alternative method for applying traction on the cricoid ring. This device retains the key functional elements of the RFST and still provides for the advantages of portability and use of a cuffed endotracheal tube. Although this novel device is used with a technique that is very similar in approach to the RFST, we opted to compare this device with the current accepted standard open surgical technique. The objective of this study was to compare this new cricothyrotomy device with a standard surgical crichothyrotomy technique with respect to ease of use and time to intubation.
METHODS Study Design. This was a prospective, randomized, crossover trial comparing two techniques for cricothyrotomy, using recently euthanized sheep. This study was reviewed and approved by the institution’s animal care and research committee. Figure 1. The investigational device.
Figure 2. The device demonstrating attachment to a #20 scalpel.
Study Setting and Population. Twenty white-faced Suffolk or Hampshire crossbred sheep underwent cricothyrotomy immediately after having been euthanized for an unrelated hemorrhage study. The anterior neck was shaved in preparation for the procedure. Each of the participating second- and third-year emergency medicine (EM) residents were initially randomized to one of the two techniques and then crossed over to perform the other technique. None of the residents had previously performed the investigational technique. All of the participating EM residents had some experience with cricothyrotomy. All had performed the RFST at
least once and approximately half of the participating EM residents had performed the standard technique at least once prior to the study. Portex 8-mm (OD) cuffed tracheostomy tubes (Keene, NH) were used for this study. All of the participants watched a brief instructional video demonstrating both the standard and investigational cricothyrotomy techniques and were given a copy of a descriptive text of both methods.
Study Protocol. The standard technique was performed using an initial vertical incision with dilatation of the cricothyroid membrane with Trousseau dilators as previously described.11 The investigational device (Figs. 1 and 2) is composed of a pair of blunt arcuate hooks operatively coupled to a pair of handles by elongated shafts. The pivoting shafts are coupled to provide a scissor-like action, and the handles are angularly offset in relation to the axis of the shafts in a direction opposite to the direction of curvature of the hooks. The blade of a scalpel is placed between the hooks and held in position when the handles are closed together. The hubs on the sides of the scalpel adjacent to the blade will abut the inner radius of the hooks. This relationship limits protrusion of the blade beyond the hooks. In this way, the scalpel can be used to make an incision, but the depth of the incision is limited by the amount of blade protrusion. The method for using the investigational device is illustrated in Figures 3–8. The pertinent anatomic landmarks are initially identified by palpation. With the scalpel engaged in the apparatus, the assembly is used to incise the skin and cricothyroid membrane with a single horizontal incision. Once entry into the airway is accomplished, the scalpel is removed. The device is then rotated 90 degrees caudad and spread apart, thus allowing for blunt dissection and stretch of tissue, rather than sharp dissection. Likewise, the double hooks are able to control the laryngeal complex with the intention of avoiding excessive local traction that has been associated with injury when using a single hook.8,9 The endotracheal tube is then inserted between the hooks.
ACADEMIC EMERGENCY MEDICINE • November 1999, Volume 6, Number 11
RESULTS
Figure 3. After palpation of landmarks, a horizontal incision is made into the cricothyroid membrane.
The median time to endotracheal tube insertion for the investigational technique was significantly less than that for the standard technique, 35 seconds [interquartile range (IQR), 24 to 46 sec] vs 87 seconds (IQR, 58 to 116 sec), p < 0.01. Likewise, the median difficulty score for the investigational technique was significantly less than that for the standard technique, 1.9 cm (IQR, 0.7 to 3.2 cm) vs 4.8 cm (IQR, 3.1 to 6.6 cm), p = 0.05. Complications (hemorrhage and cartilaginous injury) were not formally assessed. There were no failed intubations.
DISCUSSION
Figure 4. Withdrawal of the scalpel from the airway. The hooks are removed from the airway by moving the handles downward toward the patient’s sternum and in turn levering the device out of the airway.
Measurements. Both techniques were assessed for time to insertion of the endotracheal tube by an observer not involved with the process of intubation. The time to insertion was recorded from the initial skin incision to the first insufflation of air through the endotracheal tube. The participating EM resident then rated the subjective difficulty based on a 10-centimeter (0 cm = easiest, and 10 cm = most difficult) visual analog rating scale.12,13
Data Analysis. Results were analyzed using paired nonparametric statistical methods (Wilcoxon signed-rank test), and p-values ⱕ 0.05 were considered significant. All tests were performed using Stata for Windows statistical software.14
This preliminary report of a new device for surgical cricothyrotomy demonstrates a significant improvement over the standard technique in terms of subjective ease of use and time to secure an invasive airway. The time savings of 52 seconds, as it applies to potential hypoxia time, can be a critical advantage. Likewise, the ease of use determination (difference of 2.9 cm on the visual analog scale, or a 250% improvement) is also of potential clinical importance as it relates to learning and later recalling such an infrequently performed procedure. Several design elements of the device merit discussion as they apply to both safety and ease of use. The key functional elements of certain surgical airway tools have been consolidated, thereby obviating the need for independent dilators or tracheal hooks. The intention of this design is to allow for easier manipulation and, thus, faster performance of cricothyrotomy. Furthermore, the nature of the device, which relies on blunt, rather than sharp, dissection, is intended to minimize the risk of bleeding that might otherwise arise if aberrant vessels were lacerated. Similarly, the use of two hooks is designed to allow control of the cricoid ring in a manner that distributes the otherwise very local force that may be applied with techniques such as the RFST. Finally, this technique may also decrease the risks of injury to the posterior airway and esophagus, as the incisional profile of the device is intended to inhibit excessive depth of insertion.
1173 LIMITATIONS AND FUTURE QUESTIONS A formal safety assessment was not part of this study, because we were unable to assess hemorrhage or cartilaginous trauma. However, an independent assessment by Davis et al. compared this device with standard technique and studied the issue of trauma to the cricoid ring. They concluded that cricothyrotomy with this device appears to lessen trauma to the cricoid ring over the RFST and confirmed our findings with respect to the standard surgical technique and time to intubation.15 We were unable to formally assess the possibility of complicating hemorrhage, because as the nature of the animal model (i.e., euthanized
Figure 5. Caudal rotation of the device.
Figure 6. Spreading of the hooks with blunt dissection of tissue.
Figure 7. Placement of the endotracheal tube between the hooks of the device.
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Figure 8. The handles are moved downward and the hooks are levered out of the airway. sheep) did not allow for any quantification of blood loss. Likewise, postoperative dissection to document soft-tissue damage from either technique was not performed in this study. However, prior to the data gathering phase of the study, tracheal endoscopy was used to observe the laryngeal structures during the performance of multiple cricothyrotomies. During this purely observational phase, we did not observe any evidence of complicating trauma to the laryngeal structures from the investigational device.
CONCLUSIONS The use of this novel device for cricothyrotomy resulted in faster and easier intubations over a standard surgical technique. This device may be a significant addition to standard emergency airway equipment. This device warrants further investigation to determine its utility in clinical practice. — AARON E. BAIR, MD (e-mail:
[email protected]), Division of Emergency Medicine, Department of Internal Medicine, U.C. Davis Medical Center, Sacramento, CA; and JOHN C. SAKLES, MD, University of Cincinnati, Cincinnati, OH This project is dedicated to the late B. Tomas Brofeldt, MD, inventor of the rapid four-step technique, whose infectious enthusiasm, intellectual curiosity, and constant advocacy continue to be a source of inspiration. A special thanks to Nathan Kuppermann, MD, MPH, for his
statistical support and assistance with the preparation of the manuscript. Presented at the SAEM annual meeting, Washington, DC, May 1997.
Key words. cricothyrotomy; cricothyroidotomy; surgical airway access; failed intubation; airway management.
References 1. Melick C, Rosen P. Cricothyrotomy and tracheotomy. In: Dailey RH, Simon B, Young GP, Stewart RD (eds). The Airway: Emergency Management. St. Louis: Mosby–Year Book, 1992. 2. Sakles SC, Laurin EG, Rantapaa AA, Panacek EA. Airway management in the emergency department: a one-year study of 610 tracheal intubations. Ann Emerg Med. 1998; 31:325–32.
3. Chang RS, Hamilton RJ, Carter WA. Declining rate of cricothyrotomy in trauma patients with an emergency medicine residency: implication in skills training. Acad Emerg Med. 1998; 5:247– 51. 4. Weiss S. A new emergency cricothyrotomy instrument. J Trauma. 1983; 23: 155–8. 5. Toye FJ, Weinstein JD. Clinical experience with percutaneous tracheostomy and cricothyrotomy in 100 patients. J Trauma. 1986; 26:1034–40. 6. Ciaglia P, Firsching R, Syniec C. Elective percutaneous dilational tracheostomy. Chest. 1985; 87:715. 7. Brofeldt BT, Panacek EA, Richards JR. An easy cricothyrotomy approach: the rapid four-step technique. Acad Emerg Med. 1996; 3:1060–3. 8. Holmes JF, Panacek EA, Sakles JC, Brofeldt BT. Comparison of 2 cricothyrotomy techniques: standard method versus rapid 4 step technique. Ann Emerg Med. 1998; 32:440–6. 9. Davis DP, Bramwell KJ, Vilke GM, Rosen PB. Cricothyrotomy technique: standard technique versus the rapid four step technique. J Emerg Med. 1999; 17: 17–21. 10. Griggs WM. Cricothyrotomy concern [letter]. Acad Emerg Med. 1997; 4:1006– 7. 11. Mace S. Cricothyrotomy. In: Roberts JR, Hedges JR (eds). Clinical Procedures in Emergency Medicine. Philadelphia: W. B. Saunders, 1997. 12. McCormack HM, Horne DJ, Sheather S. Clinical applications of visual analogue scales: a critical review. Psychol Med. 1988; 18:1007–1019. 13. McDowell I, Newell C. Pain measurements. In: Measuring Health: A Guide to Rating Scales and Questionnaires. New York: Oxford University Press, 1996. 14. Stata Corp. Stata Statistical Software: Release 5.0. College Station, TX: Stata Corporation, 1997. 15. Davis DP, Bramwell KJ, Hamilton RS, Chan TC, Vilke GM. Cricothyrotomy speed and safety: a comparison between standard open technique and rapid fourstep technique using a novel device [abstract]. Acad Emerg Med. 1998; 5:483.
Thrombolytics and Stroke: What Do Emergency Medicine Residents Perceive? The use of thrombolytics in acute stroke remains controversial, and the attitudes of emergency medicine (EM) residents on this topic are unclear. It might be hypothesized that as young physicians in training, they would be very likely to be exposed to thrombolytic therapy (as by definition, they work in teaching hospitals) and would therefore be
quite likely to embrace this innovative approach with some enthusiasm. On the other hand, it is possible that they would have a more skeptical perspective and be relatively more resistant to the intense marketing efforts that this therapy has engendered. The purpose of this direct-mail survey was to determine the percep-
