Emergency surgical tracheotomy in the era of COVID-19 pandemic

1.1 COVID-19 pandemic and SARS-CoV-2-related ARDS

At the end of 2019, a few cases of severe pneumonia of unknown origin were reported among individuals from a live animal market in Wuhan, in the Chinese province of Hubei [1]. A novel variant of beta-coronavirus, named Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was identified in the bronchoalveolar lavage samples of these patients.

SARS-CoV-2 was proved to be responsible for the development of a large clinical spectrum of diseases, collectively called Coronavirus Disease 2019 (COVID-19), ranging from asymptomatic or subtle symptomatic infections to severe acute distress respiratory syndrome (ARDS). Being the replication of the virus mainly located in the nasopharyngeal tract cells, the respiratory droplets and aerosols from carriers swiftly caused the transmission of the infection worldwide [2]. On March 11th, 2020, COVID-19 was declared a pandemic by the World Health Organization (WHO) [3].

Oxygen therapy delivered by nasal cannula, Venturi mask, or reservoir to maintain an oxygen saturation of hemoglobin over 90% is the mainstay of treatment at every stage of disease of hospitalized patients with SARS-CoV-2-related pneumonia [4]. Although several molecules, including corticosteroids, antimicrobial and antiviral drugs, immunomodulatory, and anticoagulants, have been used to treat the disease in the context of clinical trials, there is still no specific therapy uniquely approved by international organisms [5]. After the completion of the third phase of clinical trials, a nucleoside-modified RNA BNT162b2 vaccine has recently been released, promoting immunization against a membrane-anchored SARS-CoV-2 full-length spike protein [6]. A massive vaccination campaign is currently running in Italy and many other countries worldwide, aiming at a definitive eradication of the disease.

Despite the proportion of patients requiring hospital admission is relatively low compared to the total number of infected subjects, up to two-thirds of them require intensive care at the onset of respiratory failure [2]. With the pandemic outbreak, therefore, the number of patients with COVID-related severe ARDS progressively increased.

The rate of patients with viral pneumonia and concurrent bacterial infections is variable, ranging from 1% to 12% [7, 8]. Nevertheless, both community and hospital-acquired coinfections are widely perceived to possibly increase morbidity and mortality in COVID-19 patients. Empirical antibiotic therapy is generally recommended in these patients despite the possibility of multi-drug resistance development. In a study by Cataldo et al. on patients with severe COVID-19 pneumonia in the ICU setting, 49% of subjects developed a bloodstream infection after a median of 13 days of hospitalization [9]. Fungal infections by Candida spp were evident in about 10% of patients. Therefore, concomitant bacterial and fungal infections at presentation and during hospitalization may enhance the possibility of unfavorable clinical evolution in patients affected by SARS-CoV-2 related disease.

The mortality rate among patients with ARDS is very high, exceeding 30%. Despite some authors in the early phase of pandemic asserted that patients affected by COVID-19 might show unique characteristics [10], it was later demonstrated that these patients could be successfully treated with therapeutic approaches similar to those with severe respiratory impairment from other causes [11].

Early recognition of patients at risk for severe clinical evolution is crucial. Several factors have been evaluated for the risk stratification of patients with SARS-CoV-2 infection presenting at the emergency department. Balzanelli et al. showed that gas exchange profile at arterial blood gas (ABG) analysis could predict the presence of pulmonary CT scan alterations in a subgroup of patients presenting with alkalosis, hypoxemia and hypocapnia [12]. This finding was further confirmed by two additional studies reporting that both the incidence of inflammatory infiltrates at chest CT scan and poor prognosis were correlated with higher pH value, and lower pCO₂ and pO₂/FiO₂ ratio evaluated at ABG analysis [13, 14].

Among symptomatic patients, 14% show a severe evolution, and 5% become critical within two weeks after the onset of the disease. Endotracheal intubation and mechanical ventilation should be considered in presence of refractory hypoxemia, hypercapnia and acidosis, respiratory musculature exhaustion, and hemodynamic instability despite the use of maximal non-invasive respiratory support and pronation [15].

After intubation, most patients are managed with lung-protective ventilation, which involves low tidal volumes and positive end-expiratory pressure (PEEP) rate adequate to guarantee alveolar recruitment [16].

The choice of appropriate timing for endotracheal intubation (ETI) is fundamental not only to obtain better short- and long-term outcomes, but also to avoid potential complications related to ETI failure, in particular when facing emergency intubation. In the series presented by Zheng et al., the incidence of unexpected troubles during ETI in 59 SARS-CoV-2 positive patients with respiratory failure has been reported to be 8.5% [17]. In this study, the rate of unsuccess at first intubation attempt was significant despite the use of a video laryngoscope - ranging between 6.5% and 16.7% depending on the tool employed - and the application of rapid sequential induction and intubation protocol by skilled operators. The advanced age of COVID-patients, the high rate of cardiovascular comorbidities, the coexistence of hypoxia and hypotension secondary to ARDS and multiorgan failure at the time of intubation, and the scarce time for the assessment of potentially difficult airway are all critical factors that have been recognized to be responsible for an increased probability of intractable ETI failure [17, 18], and therefore, for the need of rescue procedures.

1.2 The emergency surgical airway (ESA)

In the emergency setting, the inability to ensure a proper ETI for patient ventilation and oxygenation - the so-called ‘Cannot-Intubate-Cannot-Oxygenate’ (CICO) scenario - is one of the factors most affecting short-term prognosis [19]. Although performed by experienced operators, the rate of failed intubations in trauma patients is not negligible. In the study by Ono et al., over 23% of 537 patients had at least one complication related to ETI, and 5% of them underwent a rescue emergency surgical airway (ESA) procedure due to intractable ETI failure [20]. Furthermore, it has been reported that ETI failure occurs during elective procedures in about 1 over 50,000 cases, with very high related mortality, up to 25% overall [19]. In the meta-analysis by Cabrini et al., despite preoperatively predicted difficult airway, failed ETI was reported in about 0.6% of patients who underwent an awake intubation attempt by fiberoptic guidance [21].

According to the latest guidelines of the Difficult Airway Society, when tracheal intubation cannot be accomplished, the first indication is the placement of a supraglottic non-invasive device, e.g. a laryngeal mask [22]. However, in a considerable proportion of patients these devices and subsequent face-mask ventilation fail to provide adequate oxygenation; thus, an ESA rescue procedure is required [22].

Four different ESA procedures are available so far, and the choice is strongly influenced by factors related both to the patient characteristics and to the operator preference and skills: needle cricothyrotomy (CT), scalpel CT, percutaneous dilatational tracheotomy (PDT), and open surgical tracheotomy (OST) [23]. Technical details about OST will be reported in Section 2.2.

In case of severe hypoxemia, the fastest method to provide oxygen delivery inside the airway is a needle CT, a simple procedure that involves positioning a large-bore needle through the cricothyroid membrane and connection to an oxygen circuit. Nevertheless, needle CT should be considered a temporary solution to be followed by a definitive procedure (i.e. tracheal intubation whenever feasible, or tracheotomy) as soon as possible after the critical situation has been relieved [24].

Surgical or scalpel CT is the procedure of choice suggested by the Advanced Trauma Life Support (ATLS) guidelines for the establishment of an ESA [24]. The cricothyroid membrane is identified and incised with a scalpel; the incision is enlarged with a hemostat, and a tracheostomy cannula is inserted in the airway and connected to ventilation.

PDT is a multi-step guidewire-based procedure that is usually conducted under direct endoscopic control with bronchoscopy. Ciaglia first conceived this technique in 1985; since then, several kits with minor variations of the procedure have been released on the market [25]. Compared to surgical approaches, PDT allows saving time, as it is a bedside procedure technically faster than an OST, once the learning curve has been completed. The incidence of perioperative major complications and mortality is low (8.7% and 0.3%, respectively), and it is comparable to that reported in patients undergoing OST [26]. However, in the emergency setting, it is widely accepted that OST may be preferable over PDT due to the lower incidence of intraprocedural difficulties [26].

Hence, the CICO scenario is burdened by the high rate of morbidity and mortality. The establishment of preventive actions allows a reduction of such risk. Some measures have been adopted on an institutional basis, as the creation of dedicated ‘difficult-airway management teams’ [27, 28]. Moreover, the careful evaluation and the early identification of at-risk patients enable specifically targeted procedures to be implemented, as described by Britt and colleagues, who suggested the temporary exposure of the tracheal wall to ease the institution of an ESA at the end of neck surgery on patients with predicted difficult anatomy [29].

2.1 Patient positioning and anatomical landmarks

In the case of ETI failure, timing is critical and ideal conditions to perform a surgical tracheotomy cannot be always guaranteed [30]. However, efforts should be done to ensure conditions as similar as possible to elective tracheotomy to reduce periprocedural complications and achieve optimal results.

The patient should lie in a supine position with the head extended to expose the airway, particularly in presence of a patient with a small and stocky build. A rolled drape is placed under the scapulae to ensure appropriate extension.

The cricoid prominence and the suprasternal notch are identified as anatomical landmarks (Fig. 1A). The cricoid cartilage should be considered the referral point for the incision because the airway position is dependent on the grade of extension of the head, and the patient’s build, and not on the position of the sternal notch [31].

Fig. 1.Technique of open surgical tracheotomy. Anatomical landmarks for skin incision to perform an emergency open surgical tracheotomy. (A) A vertical incision (dotted line) is created on the midline between the cricoid cartilage (1) and the sternal jugular incisure (2). (B) After thyroid isthmus division, the anterior tracheal wall is approached with an inverted ‘H’ shaped incision (arrow) leaving intact the cricoid and the first tracheal rings. (C) The trachea is opened and (D) A tracheal cannula is inserted through the stoma. The wound is then closed around the cannula with interrupted silk stitches.

2.2 Procedure

In contrast to what is suggested for elective tracheotomy, emergency OST begins with a midline vertical skin incision, starting from the cricoid and directed towards the jugular incisure of the sternum, to avoid hemorrhagic complications due to injuries of brachiocephalic structures or anterior jugular veins [30, 32]. Moreover, vertical-shaped access allows better retraction of the borders of the wound and visualization of the surgical field, with the only disadvantage of worst cosmetic results once the tracheostomy has been removed [33].

The subcutaneous tissue and the platysma are dissected, and the neck strap muscles are divided on the median raphe. The thyroid isthmus is encircled, divided and the edges are sutured to expose the cricoid cartilage and the upper tracheal rings.

The pretracheal fascia is opened, the trachea is sectioned preserving the cricoid and the first tracheal rings to reduce the risk of late subglottic stenosis. In our Institute, we usually perform an inverted ‘H’ incision between the second and the third tracheal ring (Fig. 1B); still, according to the operator preference, the tracheal wall may as well be approached with a simple vertical incision [31] or with the creation of a mucous-cartilaginous flap fixed at the skin edges of the incision [32].

Once the trachea is opened (Fig. 1C), a cuffed tracheal cannula is introduced secured either with stitches to the skin or with a tape around the neck (Fig. 1D). The type of tracheal cannula is chosen based on the patient’s physical constitution and the reason for the respiratory emergency. In case no tracheal cannula is available, the patient can be temporarily ventilated with an orotracheal tube placed through the tracheostoma.

4.1 ETI failure management in COVID-19 patients

A very unstable clinical presentation is more common in patients affected by severe SARS-CoV-2-associated pneumonia, a situation that may abruptly evolve to acute respiratory failure necessitating endotracheal intubation. Since several concurrent cardiovascular and respiratory factors may enhance the possibility of difficult airway management [17, 18], a thorough evaluation of patients at risk and the establishment of preventive planned measures will reduce the occurrence of improperly demanding emergency procedures [43].

In this context, a factor that has to be considered of paramount importance is the risk of SARS-CoV-2 transmission to the healthcare staff. Following the SARS outbreak in 2002, it was demonstrated that mask ventilation before intubation, tracheotomy, and tracheal intubation lead to a three- to a six-fold increase in the risk of viral transmission to the operators [44]. Other procedures with manipulation of the airway, e.g. fiberoptic bronchoscopy, carry a significant risk of infection for the involved personnel. The early phase of the COVID-19 pandemic confirmed this trend: in fact, health professionals composed up to 28% of all cases in some states of the USA [45].

Hence, society guidelines have been recently released to specifically address the management of critical airway emergencies during the current pandemic [46, 47, 48]. Despite a univocally shared consensus on the most appropriate approach in SARS-CoV-2-positive patients has still not been defined, most authors agree that similar measures should be adopted both in the case of patients with a definitive diagnosis as well as to those with undetermined COVID-19 status [49, 50]. The primary aim of these recommendations is twofold: first, to give evidence about the most appropriate management with a systematic description of procedures that proved to be effective in the case of CICO scenario in this particular subset of patients. Second, to promote the most indicated measures to guarantee the safety of the healthcare professionals. In fact, in almost all of these guidelines, there is a large concern about the suggestion of adequate personal protective equipment (PPE), and the application of standardized measures by dedicated intubation and surgical teams composed of skilled operators [46, 51, 52].

Certainly, the risk of viral spread during airway rescue procedures is the main reason for the amendments made to traditional protocols. While some authors privilege to place a supraglottic device followed by bronchoscope-guided tracheal intubation advocating a less traumatic manipulation of respiratory mucosa [46, 49, 53], others recommend that an emergency front-of-neck airway (eFONA) approach is preferable with acceptable rates of aerosolization if performed under protocols conditions [54]. Current indications for difficult airway management in COVID-19 patients are summarized in a flowchart (Fig. 2).

Fig. 2.Flowchart of management of difficult airway in patients with suspected or documented SARS-CoV-2 infection.

4.2 Emergency tracheotomy: a review of the existing protocols

Despite the magnitude of the problem of the lost airway in COVID-19 patients, international recommendations addressing OST procedure in detail are still lacking. Since the beginning of the SARS-CoV-2 outbreak, Slovenian national guidelines are to date the only ones available with specific indications for the safe management of CICO scenario with OST in patients with documented or suspected infection by novel coronavirus [33]. Nevertheless, the expertise gained during the SARS emergency in 2002 constitutes precious evidence to build up a baseline, with particular regard to healthcare workers’ protection [45].

Although a common opinion on the best practice for tracheotomy performance in COVID-19 patients has still not been reached, the high risk of incidental contamination of operators during the procedure is still the most feared complication. Moreover, the emergency OST procedure has only been marginally covered by documents focusing on indications for elective tracheotomy in COVID-19 patients that require long-term mechanical ventilation (Table 1). Many authors agree that a careful application of elective treatment principles to the emergency setting allows lowering notably the risk of infection transmission to the healthcare providers [43, 46, 48, 57].

In several reports, emergency OST was employed in patients with head and neck cancers [58, 59, 60]. The unique features of these patients, besides to challenge imposed by COVID-related respiratory failure, require the application of tailored procedural modifications that contribute to the creation of further knowledge about the most appropriate methods for the conduction of OST procedure in SARS-CoV-2 positive patients.

Essential recommendations to perform an OST during the COVID-19 pandemic are reported in Table 2.