Thursday, March 17, 2016
By Alok Dubey MD, Associate professor, Pedodontics Department, College of Dentistry, Jazan University, Saudi- Arabia
Maxillofacial injuries are the result of high-velocity trauma arising from road traffic accidents, sports injuries, falls and gunshot wounds. Airway management of patients with maxillofacial trauma is challenging. The clinical status and features of the trauma dictate the approach for securing the airway. The first priority in these patients is airway maintenance with cervical spine stabilisation and control of bleeding. Anaesthesiologist must be conversant with the alternative techniques for securing the airway.
Maxillofacial injuries need special attention since it involves difficult airway due to fracture of facial bones. Further, the airway is shared with surgeon and restrictions are imposed during surgery. Management of the airway is a major concern in patients with maxillofacial trauma as a compromised airway can lead to death. Gruen et al found that failure to intubate, secure or protect the airway was the most common factor related to patient mortality, responsible for 16% of inpatient deaths1.
In the Emergency Department, severely injured patients should be evaluated by following the “ABCs” of the primary survey of Advanced Trauma Life Support protocol. A patent airway should be immediately established by placing the patient in the lateral position and pulling the mandible or maxilla forward thus allowing blood and secretions to drain out of the oropharynx. Fractured teeth, foreign bodies, and blood should be cleared from the oral cavity. Attempts to control the bleeding including direct pressure, acute reduction of fractures, and placement of nasal packs or nasal airways should be done2.
Safe and optimal airway management of the patient with maxillofacial trauma requires understanding of the nature of the trauma. There are several maxillofacial injuries that require immediate treatment, especially in acute upper airway compromise and/or when profuse hemorrhage occurs. According to Hutchison et al., there are six specific situations associated with maxillofacial trauma, which can adversely affect the airway3.
The maxillofacial trauma patient often presents a problem of difficult mask ventilation and difficult intubation. The trauma usually disrupts the normal anatomy and causes oedema and bleeding in the oral cavity. The mask cannot be properly close-fitted to the face, to enable effective mask ventilation. Furthermore, an injured airway may prevent efficient air transferring from the mask to the lungs. The challenge in performing the intubation arises mainly from a difficulty in visualizing the vocal cords with conventional direct laryngoscopy. The oral cavity, pharynx and larynx may be filled with blood, secretions, debris, soft tissue and bone fractures, all of which preclude good visualization of the vocal cords.
The oropharynx and nasopharynx are frequently compromised in severe maxillofacial trauma, posing an immediate threat to the airway from resulting deformity or from aspiration of teeth, dentures bone and blood. Reduced level of consciousness from associated closed head injury or shock, may progressively result in airway obstruction.
Airway problems are particularly evident with the fractures of the mandible. Bilateral fracture may result in a floating mandible. Such victims must sit upright, leaning forward so that a suspended tongue and suprahyoid muscles do not fall out of the airway. In a seated, cooperative patient suction of the airway and oral intubation may secure the airway.
Maxillary fractures are less often associated with direct airway obstruction but may compromise the airway by causing severe bleeding from the fracture sites or from laceration of ethmoidal arteries.
Lefort III fractures (separation of cranial and facial skeletons) are usually associated with basal skull fractures. Attempts at nasal intubation may force the endotracheal or nasogastric tube through the cribrifom plate into the subarachanoidal space or into brain. Airway obstruction involving Lefort III is usually managed by awake tracheostomy. Submandibular transmylohyoid intubation has been suggested as an alternative to tracheostomy.
According to the Advanced Trauma Life Support (ATLS) recommendations for managing patients who sustained life threatening injuries, airway maintenance with cervical spine immobilization is the first priority.
The first action in the process of early airway management is preoxygenation, which may prolong the time interval up to hypoxemic state. Effective preoxygenation of the lungs increases oxygen content in the functional residual capacity which is the principal oxygen store during apnea. In some patients preoxygenation is not feasible due to the maxillofacial trauma itself, and hypoxemia is to be expected.
There are numerous airway management devices; however, only an endotracheal tube or tracheostomy tube is considered definitive when applied. Having an unobstructed view of the vocal cords of the patient with maxillofacial trauma is the main obstacle for performing successful endotracheal intubation in such patients. Numerous airway devices and strategies have been developed to overcome this obstacle.
Some devices, such as the flexible fiber-optic bronchoscope (FOB), enable a direct view of the vocal cords. Other devices, such as the laryngeal mask airway (LMA) or the double lumen esophageal-tracheal Combitube, can be inserted blindly and do not require view of the vocal cords by any means. Another option for endotracheal intubation of a patient with maxillofacial injury is to place an LMA and then pass an endotracheal intubation tube through the LMA.
The final option is the surgical one: to establish a direct access to the trachea by performing a cricothyroidotomy or a tracheotomy.
A difficult airway cart with laryngeal mask airways, combitubes, fastrach (intubating laryngeal mask airway), fiberoptic bronchoscope, cricothyroidotomy kit, tracheal tube introducer, Eschmann stylet “gum elastic bougie”, ETT changer with jet ventilation capability, Sanders jet ventilator, tracheostomy tray and retrograde intubation kit should be kept ready.
Factors which determine the possible technique of securing the airway are:
Various techniques of airway management in facial trauma include oral intubation, nasal intubation under direct vision, blind nasal intubation, fibreoptic guided nasal intubation, submental intubation and tracheostomy. In cases of panfacial trauma intermaxillary fixation in normal dental occlusion is surgical necessity to do accurate plating of various mandibular and maxillary fractures, so nasal intubation is preferred over oral intubation. If nasal bone reduction is also to be done along with maxillary and mandibular plating then submental intubation or tracheostomy remain the possible methods of airway management.
Alternative techniques like submental, submandibular and retrograde intubations need more expertise, but can provide efficient airway control. Intraoperative manipulations may cause significant displacement of endotracheal tube and should be addressed.
Mid-face fractures of Le Fort Type II and III may be displaced posterior-inferior by along the inclined plane of the base of the skull, blocking the nasal airway. Nasal intubations may be difficult and require disimpacting by pulling the maxilla forward in the mouth. This fact should also be kept in mind while the surgeon does so during surgery. Nasal tube may be pulled out leading to inadvertent extubation6.
Surgical airways are required when basic interventions and intubation are not likely to succeed (e.g., severe upper airway anatomic distortion from mid or lower facial trauma) or have failed, and is best performed early (before hypoxemia, hypercarbia, apnea occurs).
Cricothyroidotomy and translaryngeal jet ventilation are safe and more readily applicable. Tracheostomy is generally reserved for non-emergent situation with the exception of patients with laryngeal fracture.
Submental orotracheal intubation was developed in order to avoid the need for tracheotomy and to permit unfettered access to the oral region. This type on intubation is done (a) in patients with comminuted fracture of the midface or the nose, where nasal intubation is contraindicated, (b) in patients who require restoration of the occlusion, and (c) in patients whose condition permits extubation at the end of surgery. However, this type of intubation is contraindicated in patients with comminuted mandibular fractures.
In order to avoid tracheostomy and submental intubation, initially nasal intubation (with or without fiberoptic assistance) for zygomatico-maxillary and mandibular plating is done. After plating, intermaxillary fixation is opened and nasal tube is changed to oral for the purpose of nasal bone reduction.
The patient with a difficult airway is also at high risk for postoperative complications. Following surgery, the mucous membranes are edematous, the soft tissues are swollen, and the airway may be compressed. Neck expandability is relatively low and even a small hemorrhage in the region could result in airway compromise.
In intubated patients with maxillofacial trauma, extubation should be deferred until the edema subsides. During extubation the patient should be monitored closely and the care providers should be prepared for the possibility of reintubation. For those patients with a tracheotomy tube, the patient may be awakened and allowed to breathe spontaneously through the tracheostomy tube for a few days in order to ensure a safe recovery.
Patients having maxillofacial injuries with or without cervical spine fractures and head injury need securing of airway by the anaesthesiologist or trauma surgeon.
ATLS protocol must be followed in all cases of maxillofacial trauma and associated injuries addressed according to the priority6.
Airway management of the maxillofacial trauma patient is complex and requires both sound judgement and considerable experience, which are gained in similar emergency situations. Skillful and experienced personnel are mandatory, as is collaboration by the anesthesiologist, maxillofacial surgeon, ENT specialist or general surgeon, in order to have an outcome with minimal risks and maximal success5.
Airway management in maxillofacial injuries.