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April 1, 2013 Volume 77, Number 4
Airway Management Controversies in Trauma Care Thomas E. Grissom, M.D., F.C.C.M.

Albert J. Varon, M.D., M.H.P.E., F.C.C.M.



“The most savage controversies are about matters as to which there is no good evidence either way.”
— Bertrand Russell


Although the number of anesthesiologists with a dedicated trauma-based practice is very small, the majority of anesthesiologists can still encounter trauma patients requiring urgent airway management. Whether we are providing primary coverage in the emergency department (ED), backing up the ED staff for difficult or failed intubations or taking the patient to the operating room, these patients can present many challenges. Hemodynamic instability, time pressure, lack of patient cooperation, risk of aspiration, need for cervical spine protection and facial injuries frequently contribute to the difficulty of airway management. The ASA Difficult Airway Algorithm continues to serve as a starting point for trauma airway management, but may require modifications as outlined by William Wilson, M.D. in a previous edition of the ASA NEWSLETTER.1 Such strategy differs from the ASA algorithm in that waking up the patient or canceling the procedure is rarely an option because the need for emergency airway control will presumably remain. This article focuses on recent developments in airway management, published recommendations and practice observations that may alter the approach to these challenging patients.

The decision to use cricoid pressure (CP) for patients undergoing rapid-sequence induction continues to generate controversy, and recently published guidelines from organizations other than ASA have recommended elimi-nating its use or consider it an optional measure.2-4 The use of CP in the trauma patient was recently addressed in the Eastern Association for the Surgery of Trauma (EAST) prac-tice management guideline “Emergency Tracheal Intubation Immediately Following Traumatic Injury.”2 Based on evidence that CP may worsen the laryngoscopic view, impair bag-valve mask (BVM) ventilation efficiency and not reduce the incidence of aspiration, the use of CP was removed as a level 1 recommendation. Similarly in 2010, the Scandinavian Society of Anaesthesiology and Intensive Care Medicine in its “Clinical Practice Guidelines on General Anaesthesia for Emergency Situations” determined that the use of CP is not mandatory and leave its use up to individual judgment.3 This trend has also continued in other areas of emergent airway management with the 2010 American Heart Association “Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care” stating: “the routine use of cricoid pressure during airway management of patients in cardiac arrest is no longer recommended.”4 Despite these trends, CP continues to be the standard for rapid-sequence induction (RSI) in the U.S. due to its low risk/benefit ratio. In a recent national survey of teaching hospitals, 91 percent of participants indicated the use of CP as part of their modified RSI technique.5 Furthermore, the most recent guidelines of the American College of Surgeons’ Advanced Trauma Life Support (ATLS) course include cricoid pressure as a component of RSI.6 It is our opinion that CP should be applied throughout induction and attempts at intubation in trauma patients. However, if necessary, CP should be altered or removed to ease intubation or insertion of a laryngeal mask airway because securing the airway and providing ventilation should take precedence over the potential risk of aspiration.

Another controversial element of the standard RSI protocol for trauma patients is to avoid bag-valve mask (BVM) ventilation prior to attempts at intubation. This presumes that adequate preoxygenation can be obtained prior to induction, and avoidance of gastric insufflation will reduce the risk of regurgitation and aspiration. Adequate preoxygenation is often difficult to achieve in the trauma patient due to urgency, preexisting conditions such as obesity, lung injury, altered level of consciousness and combativeness. With an incidence of hypoxemia between 4-10 percent reported during RSI in the ED and over 50 percent in pre-hospital studies, many patients could benefit from gentle BVM ventilation prior to intubation. Although not well studied, many trauma anesthesiologists recommend the institution of BVM ventilation during induction to improve oxygenation in patients who are at high risk of arterial desaturation. This is especially important in patients with traumatic brain injury, where maintenance of oxygenation takes precedence over the potential risk of aspiration. Recently, the Difficult Airway Society in the United Kingdom published guidelines including a footnote that “gentle mask ventilation (inspiratory pressure < 20 cm H2O) before tracheal intubation is acceptable to some experienced practitioners”.7 This maneuver may also provide an early warning of potential BVM ventilation difficulty if intubation attempts are unsuccessful.

The use of cervical spine manual in-line stabilization (MILS) has also recently come into question. Studies have shown that it may lead to an inferior view, causing the person intubating to apply greater pressure,8 which may be transferred to surrounding tissues, including the cervical spine. Secondly, an inferior view may lead to a longer time or failure to secure the airway. Although these are legitimate concerns, MILS is still recommended by ATLS guidelines and is commonly applied in patients with suspected cervical injury (CI).6 At this time, there are no outcome data suggesting that direct laryngoscopy with MILS is inferior to any other method, including fiberoptic-guided intubation. However, the benefits of MILS must be balanced against the potential for hypoxic damage if intubation and ventilation cannot be accomplished. Therefore, as was noted for CP, MILS may be reduced if its use impedes tracheal intubation.

Finally, ongoing investigations are trying to determine the role of video laryngoscopy (VL) in trauma airway management. Two major questions exist: 1) Does VL reduce cervical motion compared to DL in patients with known or suspected CI?; and 2) Is there an improved intubation success rate with the use of VL in the trauma patient? In studies published to date, VL appears to reduce cervical motion during intubation compared to DL, although the use of MILS may reduce or eliminate this difference.9 The question of safety has not been addressed through randomized trials, but observational studies have noted similar success rates between VL and DL in the ED setting. Despite insufficient evidence, VL is increasingly being employed for patients with predictors of a difficult airway.9 It is likely that VL as a primary tool will see increasing use in trauma airway management and may be a preferred technique in patients with known or suspected CI or in patients with predictors of a difficult airway.

The patient with trauma presents unique challenges for airway management. While the anesthesiologist’s role in initial trauma airway management has changed in many institutions, there will likely be a continuing need for a team approach given the complex nature of these patients – both in and out of the operating room. Well-conducted randomized controlled trials are needed to show the benefit of video laryngoscopy compared with direct laryngoscopy as well as the role of CP and MILS for the patient with trauma treated in the ED setting.



Thomas E. Grissom, M.D., F.C.C.M, Col. (retired), USAF, is an Associate Professor, Department of Anesthesiology, University of Maryland School of Medicine, R. Adams Cowley Shock Trauma Center, Baltimore.

Albert J. Varon, M.D., M.H.P.E., F.C.C.M. is Professor and Vice Chair for Education, Department of Anesthesiology, Chief of Anesthesiology, Ryder Trauma Center, University of Miami Miller School of Medicine and Jackson Memorial Hospital, Miami.


References:
1. Wilson WC. Trauma: airway management. ASA Newsl. 2005;69 (11):9-16.
2. Mayglothling J, Duane TM, Gibbs M, et al. Emergency tracheal intubation immediately following traumatic injury: an Eastern Association for the Surgery of Trauma practice management guideline. J Trauma Acute Care Surg. 2012;73(5 suppl 4):S333-S340.
3. Jensen AG, Callesen T, Hagemo JS, et al. Scandinavian clinical practice guidelines on general anesthesia for emergency situations. Acta Anaesthesiol Scand. 2010;54(8):922-950.
4. Field JM, Hazinski MF, Sayre MR, et al. Part 1: executive summary, 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010;122(18 suppl 3): S640-S656.
5. Ehrenfeld JM, Cassedy EA, Forbes VE, et al. Modified Rapid Sequence Induction and Intubation: A Survey of United States Current Practice. Anesth Analg. 2012;115:95–101
6. American College of Surgeons’ Committee on Trauma. Advanced Trauma Life Support. 9th Edition. Chicago: American College of Surgeons; 2012.
7. Rapid sequence induction - guidelines. Difficult Airway Society website. http://www.das.uk.com/guidelines/rsi.html. Accessed January 28, 2013.
8.  Santoni BG, Hindman BJ, Puttlitz CM, et al. Manual in-line stabilization increases pressures applied by the laryngoscope blade during direct laryngoscopy and orotracheal intubation. Anesthesiology. 2009;110(1):24–31.
9. Aziz M. Use of video-assisted intubation devices in the management of patients with trauma. Anesthesiol Clin. 2013;31(1):157-166.