The present study has the particular interest of being the first descriptive report of a series of PHNT in civilian practice in a French Trauma Center, over a long 9-year period at the level of a whole administrative area (Département). The single-center design ensured homogeneity of practices and thus of data. Although conducted retrospectively, the study was based on prospectively collected data from a database allowing epidemiological comparison between PHNT and the severe trauma population as a whole. It also provided precise analysis of the issue of airway management in PHNT, which has been rarely addressed specifically in the literature. Predictive factors for early definitive airway management were identified.
Airway Management
Acute respiratory failure is seen in 10–50% of cases, by direct obstruction, extrinsic compression, partial or total airway sectioning, or of neurologic origin. It is consensual that airway control, despite the difficulty of the approach, should be anticipated due to the risk of rapid respiratory distress [9]. In the present series, orotracheal intubation was difficult in 12.5% of cases, and in 25% when performed in emergency in group 1, versus 5.6% in group 2. In case of dyspnea in the emergency room (n = 6), intubation failed in 33.4% of cases, and in 100% in case of associated cervical emphysema or sucking wound. In combat, upper airway obstruction is the second cause of preventable death, after hemorrhage and ahead of compressive pneumothorax [2–4]. According to Demetriades [10] about 16% of firearm injuries and 14% of knife wounds are associated with pneumothorax; the rate was 8.9% in the present series. Cases where both chest X-ray and FAST proved negative involved anteroinferior pneumothorax following sub-xyphoid knife wound. This association is more frequent in zone I trauma (80% in the present series).
When release maneuvers and mask oxygen therapy fail, definitive airway treatment is required, with tracheal intubation with a subglottic inflated balloon connected up to the ventilation device. Even with a cricothyroidotomy kit, a balloon should be used. The present series confirmed frequent radiological signs of pulmonary inhalation. Once the airway is secured, oronasal packing is possible and effective. Pre-hospital and in-hospital algorithms determine the roles of 3 types of definitive airway: orotracheal, nasotracheal, and cervical intubation (cricothyroidotomy, tracheotomy, intubation via sucking cervical wound). Urgency and circumstances determine the method to be used. Laryngoscopic orotracheal intubation is the method of choice, with gum elastic bougie in case of difficulty. In case of failure, supraglottic airway and videolaryngoscopy can be attempted by experienced operator [11], but are likely to fail due to anatomical distorsion and/or soiling of the airway by blood. Prompt escalation to a surgical airway must be quickly considered. Cricothyroidotomy is the technique of choice. Tracheotomy is an option, but is a surgical procedure, difficult to implement in emergency [12], with dissection liable to incur blood loss for several minutes, thus not an adapted salvage procedure. It is, however, indicated secondarily to orotracheal intubation to free the operative field, improving patient comfort with earlier awakening, despite the post-traumatic pharyngolaryngeal edema. Tracheotomy is performed within hours of cricothyroidotomy, to avoid secondary laryngeal stenosis. Thus, in the present series, secondary tracheotomy was performed in 37.5% of cases. All were subsequently decannulated. In rare cases of laryngeal or tracheal sectioning with complete airway obstruction, direct insertion of the intubation probe or tracheotomy cannula through the lesion is the optimal means of airway control. We recommend systematically having Laborde forceps in the pre-hospital kits and emergency trolleys.
Optimal airway control makes orotracheal intubation difficult or even risky when performed at the accident site: risk of inhalation on a full stomach, risk of spinal instability, presence of a cervical collar, altered anatomic relations, mechanical limitation of oral opening, and blood loss into the oropharynx [13]. Nevertheless, orotracheal intubation remains mandatory in case of respiratory distress or severe cyanosis. In contrast, indications are trickier in apparently stable patients. But the literature reports no significant predictive criteria for early definitive airway management. Despite its limitations, the present study identified three: ballistic cause of trauma, hemodynamic impact with Shock Index > 0.9, and active bleeding in the emergency room. It also identified trends for certain criteria: submental impact with involvement of cervical zone III and the lower face, neurologic impact with Glasgow score < 7, and hemoglobinemia < 10 g/dL. Irretrievable loss of substance leads to difficulties hemostasis with blood loss and difficulties temporary airway control maneuvers. Prolonged transfer to hospital is a classical factor in favor of early preventive airway salvage, perhaps in conditions such as helicopter transport in which intubation is difficult. In the present series, only one cricothyroidotomy was performed in the emergency room, in a patient with dyspnea and progressive cervical hematoma following a submental ballistic suicide attempt, who had not been intubated ahead of helicopter transport that took more than an hour (Fig. 4).
Even so, the decision to intubate is always very difficult; if considered, it should be performed as quickly as possible while conditions are still favorable. A further multicenter study based on a national registry could increase statistical power and help determine optimal definitive airway management timing, notably according to transport time.
Descriptive epidemiological analysis of the series
PHNT is rare, at 5–10% of traumas treated in emergency [14], and 2% in the present series. Incidence varies geographically, and is higher in American and South African series [10, 13, 15]. In Europe, incidence is lower: 4.3/100,000 per year in London, UK [16]], and 1.3/100,000 per year in Finland [17]. Over the present study period, the median annual emergency department turnover was 34,600 patients, with 310 cases of severe trauma and 1 of PHNT every 2 months. Management is familiar in military contexts: war-scene incidence is 5–10% [18]; poor head and neck ballistic protection and asymmetric conflicts featuring improvised explosive devices (IEDs) led to increased incidence, reaching 36–55%, in French troops in Afghanistan [19, 20]. In line with the literature [16], we found male predominance and a median age around 50 years.
Frequency also varies according to circumstances and instrument. In Los Angeles [10] PHNT is caused by aggression or attempted suicide by firearms in 48% of cases, by knife wounds in 40% and blunt objects (road accidents or falls) in 10%. In the present series, 50% of cases also concerned attempted suicide, by violent means inasmuch as 86.7% of ballistic PHNTs were suicide attempts. PHNT accounts for 1.6-3% of suicide attempts as a whole [21], but is one of the most lethal means [22]. The instrument was more often a knife (42.9%) than a firearm (26.8%), probably because the latter are less readily available in France than in the USA. In wartime, the distribution is different, with 62–98% of cases involving high-velocity weapons [19, 23].
Mortality is between 3% and 6%, mainly due to massive blood loss from large vessels [1]; it is generally underestimated, as most studies exclude pre-hospital mortality, for lack of data; if this is included, mortality can be as high as 11% [19]. Nevertheless, in our series, no deaths by exsanguination were found. These patients at high risk of rapid hemodynamic and respiratory decompensation need urgent medical transport to the nearest Trauma Center [24]. In the present series, despite a mean transport time of 46 minutes (72.4% with respect to the “Golden Hour” [25]) and pre-hospital medical care in 82.1% of cases, mortality was 10.7% (not including pre-hospital deaths). In severe trauma as a whole, mortality is higher than specifically in PHNT. The present high mortality may be due to the small sample and to a recruitment bias with two treatment interruptions prescribed due to the severity of neurologic lesions in a context of advanced cancer. In 83.3% of cases, death was due to ballistic trauma in attempted suicide, impacting the submental central compartment in zone III. The only patient who died after isolated cervical trauma (zone II) showed total sectioning of the internal carotid artery and pharynx, after falling onto a metal picket (Fig. 3).
As in the literature [10], zone II predominated in purely cervical trauma, at 56.2%. The “central/lateral” classification separates the vascular axis and aerodigestive tract [19]. In the present series, the lateral compartment was the most involved (66.1%). 74% of cervical lesions (42.9% in the present series) are on the left side [26], aggressors tending to be right-handed.
Treatment in PHNT used to involve systematic surgical exploration of any wound crossing the platysma, but surgery has now become more selective [27]. Several prospective series supported selective surgery, and described algorithms [1, 15, 28]. In the present series, 87.5% of patients underwent contrast-enhanced CT, and 96.4% underwent surgery. Only 1 patient was treated non-operatively, by in-hospital surveillance. In some patients, surgical exploration confirmed the absence of life-threatening lesions, and CT findings were never falsified. Even so, simple surgical damage control with exploration to check hemostasis (especially in dry venous wounds following knife attacks), prevention of superinfection by lavage, wound care and debridement, extraction of any foreign bodies, possibly with drainage, and suturing in 2 planes was always essential. The sole indication for interventional neuroradiology was for a lateral zone III knife wound with internal carotid thrombosis. According to some authors [29–31], algorithms based on entry point are too rigid, leading to unproductive surgery, overlooked lesions with poor correlation between the location of the external wound and the internal lesions, increased hospital stay, and higher rates of complications. In 2018, Nowicki [24] described a selective attitude, independent of cervical zone, taking the whole neck as a single entity. Even so, we consider these classifications useful, especially when there is an influx of injured patients and imaging is not available, as often happens in military surgery overseas, where the surgeon is seldom specialized in head and neck. The classifications help mentalize the lesion trajectory, disclosing vascular involvement in lateral lesions or respiratory involvement in central lesions, and determining optimal strategy in borderline zones I and III.