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16.4.1 Discuss the Role of EGDs in the Trauma Patient
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EGDs are gaining popularity in managing the airway of the trauma patient when the trachea cannot be intubated.19-22 Martin et al examined the use of the LMA in the prehospital environment; the authors reported a success rate of 94% in trauma patients.21 All successful insertions were performed in 10 seconds or less. The authors investigated the effectiveness of the LMA in providing adequate oxygenation and ventilation in these patients and found that, during transport, patient oxygen saturations ranged from 97% to 100% while the end-tidal CO2 ranged from 24 to 35 mm Hg.21 These data support a role for the LMA, and other EGDs (although most studies have only examined the role of LMAs), as tools for oxygenation and ventilation in trauma patients when tracheal intubation in the field was unsuccessful.
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To address the issue of aspiration with EGDs, multiple devices have been developed with alternate channels that would allow for drainage of regurgitated gastric contents.23 The LMA ProSeal™ (see Section 12.5 for details) contains a drainage tube that extends into the upper esophagus at the distal end of the device.23 Multiple case reports suggest that the LMA ProSeal™ is effective24,25 at minimizing, although not eliminating, aspiration risk.26,27
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The Combitube™ also has the potential to protect the airway from aspiration of gastric contents. Using dye within the oropharynx, Mercer recently showed that the Combitube™ could protect the airway in most anesthetized patients.28 However, tracheal soiling was seen in 7% (2/27) of the studied patients.28 Similarly, using a pH probe in the trachea, Hagberg et al29 reported evidence of low pH in the trachea in 1 of 25 anesthetized patients (4%) using a Combitube™, suggesting possible microaspiration of acidic gastric contents.
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Recently, dual-lumen laryngeal tubes with suction and drainage (LTS-D and LTS-II) have been introduced. While these devices may allow easy ventilation and aspiration protection,18 large clinical studies are needed to assess their effectiveness in doing so.
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In summary, while these EGDs are effective rescue devices to provide oxygenation and ventilation in trauma patients, and may play an important role in providing oxygenation and ventilation in patients with difficult or impossible intubation, they do not ensure protection against the risk of aspiration of gastric contents.
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16.4.2 What Are Your Concerns with Transporting This Patient with an EGD as an Airway?
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EGDs are effective devices for ventilation; however, there are a few considerations to keep in mind during transport.
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First, these devices cannot ensure complete protection of the airway against the risks of aspiration, although many studies have not reported a significant incidence.21,22,30 There have been case reports of the successful use of the LMA ProSeal™ and LMA Supreme™ as a rescue airway in trauma,7 suggesting that it may play a role in the prehospital environment. At this time, the lack of well-designed studies of EGDs in the trauma setting would suggest supporting their use as rescue devices only if endotracheal intubation fails.
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A second concern regarding the use of EGDs in the prehospital management of the trauma patient relates to the risk of malpositioning during transport. Any change in the positioning of the EGD may impair its ability to provide effective oxygenation and ventilation and the practitioner must continuously monitor the positioning and effectiveness of the EGD during transport. The application of cervical collars to maintain in-line cervical stabilization may also cause the EGDs to shift or cause airway obstruction during transport.22
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16.4.3 What Are Your Options for Endotracheal Intubation in This Patient?
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Laryngoscopic intubation may be difficult until the patient is extricated from the vehicle. Even then, the condition of the patient in the field environment may be adverse to the successful placement of an ETT under DL. In the clinical situation in which the patient cannot be removed from the vehicle, the options for endotracheal intubation include lightwand-guided intubation, digital intubation, and intubation through an LMA or the LMA Fastrach™. However, it should be noted that techniques not requiring direct visualization, such as the lightwand, increase the potential for airway trauma. Thus, intubation with either direct laryngoscopy (if possible) or using the LMA Fastrach™ is preferable to attempts at intubation with the lightwand.
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16.4.4 Discuss the Pros and Cons of Lightwand (Trachlight) Intubation in This Patient
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Light-guided intubation using a lightwand has been shown to be an effective and safe technique for both oral and nasal-tracheal intubation.31-33 The technique of intubation using the lightwand (Trachlight™) has been described in Chapter 11.34,35
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Because of its limitations as a nonvisualizing technique, the lightwand should be reserved for situations in which alternative airway techniques are difficult or impossible. These include limited mouth opening and patient factors that would make surgical cricothyrotomy impossible (eg, lack of equipment, trauma to the anterior neck, making impossible to identify landmark, etc). In the absence of these factors, other airway management techniques would be more advantageous than the lightwand, including direct laryngoscopy and the use of EGDs (+/- intubation).32,33,36
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The disadvantages of the lightwand in this patient include possibility of a traumatized airway, and ambient lighting may make the use of a lightwand difficult. Since we are unable to rule out a traumatic airway in this patient, the use of the lightwand may lead to delays in securing the airway and may further increase the risk of hypoxemia, morbidity, and mortality.
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16.4.5 Digital Intubation
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Digital intubation (or tactile orotracheal intubation) involves the insertion of an ETT into the trachea using the fingers. It should be performed only by trained practitioners. Digital-guided intubation has been described previously (see Chapter 11). It is a safe and effective technique for airway management in the prehospital setting in an unconscious patient, requiring minimal equipment and patient access.37,38
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While facing the patient, the clinician pulls the patient's tongue forward using the dominant hand. The nondominant hand is then inserted into the oropharynx where the epiglottis can be palpated and lifted superiorly using the long finger. An Eschmann Tracheal Introducer (ETI) (if available) can then be inserted into the airway with the dominant hand. The Eschmann Tracheal Introducer is then guided anteriorly into the trachea with the index finger of the nondominant hand. Confirmation of tracheal placement of the ETI can be done in the usual manner (eg, tracheal clicks and the hold up). The ETT can then be advanced over the ETI and into the trachea, employing the nondominant hand to guide the ETT over the tongue into the trachea. The ETI is then removed and positioning of the ETT in the trachea is confirmed using auscultation and end-tidal CO2. If an ETI is not available, an ETT with stylet can be advanced into the airway and guided into the trachea (see Section 11.4). Digital intubation can also be performed using the lightwand in lieu of the ETI. This allows the practitioner to confirm placement using tactile and visual cues.
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There are relatively few studies examining the role of digital intubation in the management of a patient's airway. Stewart reported that digital intubation is a simple and useful airway technique in the prehospital environment because it can be performed with minimal head and neck movement and with a cervical collar in place.38 The presence of blood or secretions in the airway does not seem to influence its success. Similarly, Hardwick and Bluhm, in their series, report successful intubation in 58 out of 66 patients in the prehospital setting.37
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Digital intubation is an effective airway technique that, while possible, should be reserved only for those skilled in this technique. It cannot be used in patients with intact airway reflexes.
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16.4.7 Would Nasotracheal Intubation Be Suitable for This Patient?
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Blind nasal intubation would not be the first choice for airway management in this patient because of potential basal skull fracture and lack of respiratory efforts. However, in the event that the patient's condition is deteriorating rapidly, and multiple attempts at the airway have been made, it may be reasonable to consider the blind nasal technique while concurrently preparing for a surgical cricothyrotomy if the practitioner is skilled with these techniques.
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16.4.8 Surgical Cricothyrotomy
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If the airway cannot be secured (either by endotracheal intubation or with the use of an EGD), and ventilation is unsuccessful or inadequate, securing the airway using a surgical technique is indicated. Delays in proceeding to a surgical airway following a series of failed attempts at airway control, is an important cause of morbidity and mortality. Surgical airways, such as surgical cricothyrotomy (SC), should be performed only by those familiar with the techniques. Studies in prehospital airway management have reported success rates of 82% to 100% when performed by trained paramedics, nurses, or physicians. Complication rates vary from 0% to 27%.39 Details of performing SC are described in Chapter 13. The practitioner should be aware that obese patients, or those with abnormal anatomy (eg, hematoma, trauma to the neck, previous surgery, and radiation), might make identifying the cricothyroid membrane difficult. SC can be performed using either the open or Seldinger technique. To facilitate SC, there are a number of cricothyrotomy kits available (eg, Cook Critical Care, Bloomington, IN). If possible, a cuffed cricothyrotomy tube should be used to ensure effective ventilation following its placement.
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While SC may not be performed often in the prehospital environment, there is evidence that it can be performed, with reasonable success, should prehospital responders be appropriately trained.39-41 In their retrospective review of SC performed by paramedics, Fortune et al found that paramedics who were trained in SC were able to perform the technique with 64% of patients arriving in the emergency department with acceptable SC airways.41 A further 16% required minor manipulation in the emergency department.
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If cricothyrotomy kits are not available, SC can be performed with a scalpel, an Eschmann Tracheal Introducer (gum elastic bougie) and an endotracheal tube.42,43 In these reports, the authors describe the insertion of an Eschmann Tracheal Introducer (ETI) following a skin and cricothyroid membrane incision. The ETT is then guided over the ETI and acts as its own dilator of the cricothyroid membrane. The advantage of this technique is that it does not require a cricothyrotomy kit, has only three steps, and can be done quickly in an emergency. Similar to all airway management techniques, this three-step cricothyrotomy technique needs to be taught prior to its use in the field.
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16.4.9 What Would Your Overall Approach Be in the Management of This Patient's Airway?
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The management of this patient's airway must take into consideration the safety of the scene, the skills of the practitioner, the equipment available, the critical nature of this patient's injuries, and the urgency of establishing an airway. Emergency medical systems (EMS) can vary significantly in both structure and quality of care. North American EMS organizations are paramedic-based systems while other EMS organizations incorporate physicians (often anesthesiologists) and other health professionals. The variability between skill levels of prehospital practitioners precludes a generic algorithm appropriate for all responders. Rather, it would be more appropriate to have protocols based on the skill level of the practitioner.17
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Initial attempts at airway management, appropriate for responders of all skill levels, should involve simple maneuvers which may alleviate the obstructed airway or facilitate further airway interventions. This includes a jaw thrust, tongue pull, and/or insertion of an oropharyngeal airway (OPA). Chin lifts may be considered necessary, but one should proceed with caution and recognize the potential impact of cervical spine movement in a patient with a high risk of cervical spine injury.
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If the patient initiates any respiratory effort with these maneuvers, attempts at supporting the patient's airway while extrication proceeds may be sufficient—particularly if the responder has training only in basic airway management. Insufficient ventilation in this situation may necessitate assistance with BMV. This may require two-person BMV to ensure adequate delivered volumes.
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Responders possessing training beyond basic skills may continue with BMV or consider the use of other adjuncts. The LMA Laryngeal Tube™, or Combitube™ are the most commonly used prehospital airway alternatives. The skill levels required to ensure proper insertion and adequate ventilation are variable. The insertion success rates to allow adequate ventilation for the LMA Classic™ may vary between 64% and 100% when inserted by respiratory therapists and EMS providers.17,44,45 The LMA Fastrach™ may be a useful alternative because of its ease of insertion, high success rate, and ability to ventilate as well as facilitate intubation.17 In their observational study of prehospital intubations by paramedics using either the intubating LMA or direct laryngoscopy, McCall et al46 found that the rate of successful intubation of unconscious patients was 88% with the intubating LMA and 63% with DL. Nakazawa et al8 demonstrated successful intubations between 82% and 99.3% with the intubating LMA. Overall success rates, including those requiring more than one attempt, were not statistically different at 91% for DL and 92% with the intubating LMA.46 In a simulation of a difficult airway, Reeves et al47 examined the rates of successful insertion of the intubating LMA by ambulance officers, physicians with intubating experience, and physicians without intubation experience. Most importantly, they found that 100% of patients were successfully ventilated with the intubating LMA. The respective failure rates of intubation (not ventilation) in the groups were 7% (ambulance officers with intubating experience), 20% (physicians with intubating experience), and 16% (physicians without intubating experience).47 While the study by Reeves et al involved only a small group of participants, the results are consistent with other studies which suggest that success insertion rates are high with the intubating LMA in individuals with varying levels of airway management skills.17 In this situation, ventilation and oxygenation may be all that is needed until the patient can be extricated and transported to hospital. In the event that tracheal intubation is needed, the intubating LMA may facilitate the ETT placement.
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The LMA ProSeal™ (see Section 12.5) is a variant of the LMA with the potential ability to passively drain gastric contents via its esophageal vent.48 There have been case reports of the drainage tube allowing for drainage of gastric contents during active vomiting.25,49 Conversely, there have also been case reports of aspiration despite the use of the LMA ProSeal™.48
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The use of the combitube™ (see Section 12.6) in prehospital care has been well described.17 Its insertion does require training and, thus, its use should be reserved for the trained practitioner. Esophagus placement occurs 95% of the time with the remaining 5% resulting in translaryngeal placement. Successful insertion and ventilation ranges from 79% to 82.4%.17
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The practitioner with advanced training in airway management may feel comfortable using additional airway techniques beyond those already described (maneuvers to relieve airway obstruction, EGDs). Additional options, reserved for practitioners with advanced skills in airway management, include digital intubation and surgical cricothyroidotomy as described earlier.
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As with all airway management techniques, successful ventilation and oxygenation should be confirmed using colorimetry or capnography.