What's New in Critical Illness and Injury Science? A Look into Trauma Airway Management

Traumatic injury affects almost a billion people worldwide, with an 8% global mortality rate and approximately 5 million deaths reported annually.[1] Trauma is the leading cause of death and disability among young people in the United States (US).[2] Of the 170,000 traumatic deaths in the US in 2017, roughly 79,000 occurred in patients <45 years of age.[3,4] Trauma contributes to the highest number of years of life lost (30%) due to its prevalence and long-term effects on younger populations.[2] The financial burden of traumatic injuries is estimated at $671 billion US dollars annually and includes costs associated with both health care and loss of productivity.[5] Optimization of care for these patients is key, not only for mortality but also for the morbidity and financial impact that may accompany survival.

Nonburn trauma patients embody a unique population. Advanced Trauma Life Support guidelines have long focused on adherence to the “ABCs” of resuscitation beginning with Airway, and although more recent pushes have advocated addressing circulation and bleeding first (so-called CAB), airway management remains critically important.[2] Early and appropriate airway management is a vital lifesaving measure, whose delay may worsen outcomes.[6] Airway management in trauma patients is complicated due to the high risk of hemodynamic instability, agitation, and examination difficulties, which may include direct face or neck trauma, and cervical spine immobilization. The percentage of trauma patients requiring endotracheal intubation (ETI) varies depending on clinical setting. In aeromedical and ground emergency medical services, reported rates are 18.5% and 4%, respectively.[6,7] ETI is required in about 24.5% of trauma patients presenting in the US to a designated trauma center (range 9%–28%).[8] ETI indications include, but are not limited to: airway obstruction, hypoventilation, severe hypoxemia, severe cognitive impairment (often measured as a Glasgow Coma Scale ≤8), cardiac arrest, severe smoke inhalation, and severe hemorrhagic shock.[8,9]

Airway management in critically ill patients has had multiple advancements over the past 20–30 years, with ETI remaining the gold standard for most patients. Conventional direct laryngoscopy (DL) with either a Macintosh or Miller laryngoscope blade has been the standard of care in airway management since the 1940s.[10] The use of pre-oxygenation and rapid sequence intubation (RSI) has decreased periods of peri-intubation apnea and hypoxia and increased intubation success rates.[11]

Prehospital airway management centers around the goals of providing adequate oxygenation and ventilation without having a significant delay in transportation to a hospital or trauma center for definitive care. Airway support options include jaw thrust maneuver, nasopharyngeal airway placement, bag valve mask ventilation, and placement of an advanced airway such as a supraglottic airway device (SAD) or endotracheal tube (ETT).[12] SAD placement allows for lifesaving oxygenation and ventilation while limiting transportation delays, as these are blind insertion airway devices that rest above the trachea. While there are multiple SAD products, two common SADs used in prehospital care settings include the laryngeal mask airway (LMA) and esophageal tracheal airway (Combitube and King Airway).[12,13] While prehospital ETI may be appropriate for some, its use has been observed to have higher mortality rates than when performed in the ED.[14] The reasons for this remain unclear and a source of investigation.

Trauma patients presenting to the emergency department (ED) at a trauma center require ETI approximately 25% of the time.[2] The airway management challenges posed by critically ill trauma patients differ from those of their medical counterparts. Cervical spine immobilization presents a significant challenge in ETI as airway views are often limited due to the inability to flex the neck. For those with suspected intracranial hemorrhage or injury, traditional RSI may carry the additional step of premedication (e.g., lidocaine and fentanyl) 2 min prior to the induction and paralytic agents with the aim of blunting the rise in intracranial pressure that may accompany laryngoscopy.[14] Although the effectiveness of this strategy has been debated,[15] for those who practice it, there may be a delay in securing a definitive airway.

Numerous airway adjuncts and tools are available to aid the modern practitioner in securing difficult or complicated airways. The bougie, or Eschmann tracheal tube introducer, is a long flexible tubing with an anterior tip angulation (30 degrees) that is inserted through the vocal cords and acts as an introducer for ETT placement through Seldinger-like technique.[2] Flexible fiberoptic bronchoscopy[16,17] and intubating LMAs are other forms of airway adjuncts that may be helpful in challenging situations and for those experienced with their use. Moreover, while uncommon, surgical airway placement (i.e., cricothyroidotomy, retrograde intubation, submental airway, and tracheostomy), may be required (<1%) in select cases.[3,9,18]

The video laryngoscope (VL) emerged in the early 2000s,[12] and has increasingly gained wide acceptance in the prehospital, ED, intensive care unit, and operative settings. VL utilizes a camera at the tip of the laryngoscope blade to augment visualization. Advantages of VL use include improved visualization of difficult airways (anterior, small oropharynx, neck immobilization, etc.), expansion of view to other team members, and the option for the use of hyper-angulated blades with rigid stylets to access difficult airways. Disadvantages include lens fogging or obscuration by fluids and potential difficulty with placing the ETT in the same path as the laryngoscope.[19]

There have been multiple head-to-head studies looking at DL versus VL with varying results. In a 2017 Cochrane Review of 64 randomized controlled trials (7,044 participants),[20] VL did not show a reduction in the number of intubation attempts, incidence of hypoxia or respiratory complications, or change in time required for intubation when compared to DL.[20] However, it should be noted that significant heterogeneity was observed across studies relating to a lack of data on clinical location and impact of obesity on failed intubation rates.[6,13,19,21,22,23,24] The question of whether VL reduced the number of failed intubations, in particular those with difficult airways, was not addressed. Head-to-head studies have compared VL and DL in various settings (simulation, ED, ICU, and operative), and across varied operator experience levels (students, residents, fellows, and supervising/attending physicians) and specialty training backgrounds.[20,22,23,24,25,26,27] Owing in part to this heterogeneity in design and populations studied, results have been conflicting regarding the superiority of VL as it pertains to first-pass intubation success, time to intubation, and peri-intubation hypoxia.[19,25,26,27]

In this edition of IJCIIS, Louro et al. report how the immediate availability of VL in their Level I trauma center affected the approach and outcomes of airway management during acute trauma resuscitations.[28] Of note, no difference in the rate of intubation success between DL and VL was observed. ETI success rates were high, and surgical airway rates were low. This may, in part, be due to the level of operator expertise and airway protocol that was studied. All operators were anesthesiology residents with supervision by a higher trainee or attending anesthesiologist, and a protocol with DL as the preferred primary method. Whether DL is superior to VL for all-comers remains unclear in pre-hospital, ED and inpatient settings. In these settings operators are more likely to include other specialties such as EM, pulmonary medicine, critical care medicine, or even surgery specialists with varied levels of airway training. Hence, the question of whether video killed the direct laryngoscope star in all settings and practices is still debatable.