Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), which causes COVID-19, is a singlestranded ribonucleic acid-encapsulated coronavirus and is highly contagious. Transmission is thought to be predominantly by droplet spread by air, and direct contact with the patient or contaminated surfaces . The pandemic has inevitably caused some modifications in common critical procedures in order to reduce viral spread . When performing airway management by endotracheal intubation (ETI), tracheostomy, noninva- sive ventilation (NIV) and, mask ventilation physicians must be careful and follow some safety rules in patients with COVID-19 [3,4].
The staff in the emergency department (ED), particularly, must maintain a high index of suspicion when evaluating all patients, but especially those with COVID-19 symptoms (fever, cough, dyspnea, or signs of a respiratory illness). Although the Centers for Disease Control and Prevention (CDC) developed a real-time reverse transcription-polymerase chain reaction test to detect SARS-CoV-2 , the situation still remains risky for false-negative results and delays in test results.
Effective airway management has a great significance to improve respiratory support, reduce complications, and promote rehabilitation . However, patient-oriented approach has to shift to an approach focusing on providers’ safety . In this review, we aimed to focus on modifications in ETI in patients with COVID-19 and underline the importance of staff security during airway interventions.
Materials and methods
This narrative review was conducted by entering the terms ‘airway management’, ‘ETI’, ‘COVID-19’ and ‘coronavirus’ into scientific database; Pubmed©.
One of the reviewers with an experience in database searches designed the search strategy, which was subsequently revised by other reviewers. With consideration to the date of the earliest confirmed reports of COVID-19, the searches were limited to articles published in 2019 and 2020.
Articles are written in other languages than English were excluded from the study. Also, those without full-texts or explanatory abstracts were excluded.
Protective measures prior to intubation
The current World Health Organization and CDC guidance recommends clear communication of the staff, minimising personnel in the room during the procedure, appropriate use of personal protective clothing (PPE) and avoidance of procedures that generate high amounts of aerosols for the protection of personnel in the management of patients with confirmed or suspected COVID-19 . Also, clinicians must be careful for inappropriate use of equipment since the equipment is limited . Protection against aerosolization begins prior to patient enters to the hospital. EDs in most countries have a separate room or area with a portal to outside for COVID-19 patients. These rooms or areas are often located near the ambulance entrance. When a COVID- 19 patient arrives, healthcare providers accompany the patient so that the patient does not travel through the ED avoiding contamination of the clean areas .
In this separate area, a tent may be constructed for intubation procedure. It may provide a barrier if the patients coughs or gags. Transparent plastic bags draped over the patient's head to chest may be used for his purpose . A similar protection method, aerosol box, was previously described. It consisted of a transparent plastic shield covering patient's head. It also had two circular ports for the healthcare provider to insert the hands during the intubation . Fang et al. developed a novel, low-cost, easy-to-make protection tent with two components inspired by an umbrella and a raincoat to provide a protective barrier between clinicians and the patient, containing possible aerosol during intubation . However, also some obscurities about the device were reported. Following the removal of the box, the particles would still have the potential to spread and the circular ports could give damage to the protective clothes. Additionally, the box may not fit all the patients and intubation performers. The box may also block the manipulation of ancillary devices such as bougie. These factors may have a bad influence on the success of intubation . PPE in invasive procedures during pandemic is well described in the literature. Even though the role of particles in virus spread is still unclear, a surgical mask, eye protection (goggles or procedure mask with face-shield), an Association for the Advancement of Medical Instrumentation level-2 gown, and gloves that overlap the gown sleeve enough to prevent wrist exposure during movement are recommended [15,16]. An extra protection can be achieved by wearing double gloves for ETI . Antifog measures should be taken for fogging of googles and/or eyewear when using PPE during ETI. It was reported that training and practising PPE use before patient management is essential for staff and patient safety .
Into the intubation room, only healthcare providers directly involved in the intubation procedure should enter. Size of the endotracheal tube (ETT) is generally 7.5 mm for females and size 8.0 mm for males. Equipment involving a supraglottic airway device (e.g., laryngeal mask airway or i- gel), gum-elastic bougie, and Magill forceps should be ready in the room. Protective laryngeal reflexes are lost by induction medications. Therefore, suction should be readily connected and be easily accessible to prevent aspiration. Intubation must be terminated rapidly in order to minimize aerosol spread. During intubation, barrier devices, such as screens and intubation boxes should be considered. A plastic sheet can be used if a screen and intubation box are not available .
Before leaving the patient's room, gloves may be cleaned with alcohol-based hand sanitiser, gown should be pulled down and teared, the gown should be rolled inside out away from the body, hands should be cleaned with alcohol-based hand sanitiser. Then, the face-shield must be removed by touching the bands, without touching the dirty front surface. Finally, the hands should again be cleaned with alcohol-based hand sanitiser .
Endotracheal intubation in COVID-19 patients
COVID-19 may cause airway oedema and laryngitis . Management of airway in COVID-19 patients begins with noninvasive procedures. High-flow nasal cannula (HFNC) is recommended in these patients. After confirmation of upper respiratory system patency, the proper size of the nasal cannula must be selected. An initial flow of 60 L/min and 37°C should be given immediately for patients with obvious respiratory distress or weak cough ability. The aim for oxygen saturation must be above 95% in order to prevent hypoxia and hypoxemia . High-flow nasal oxygenation in critically ill patients not only provides a decrease in intubation time it also causes a less frequent incidence of desaturation during the procedure . However, Cook et al. recommend to avoid high-flow nasal oxygen (HFNO) in a situation of mass illness and mass mechanical ventilation. It may delay ETI in those for whom treatment escalation is appropriate. Additionally, the very high oxygen usage depletes oxygen stores which will probably be required during the pandemic . It was reported that HFNO is not associated with increase in air or surface contamination in a study with patients with bacterial pneumonia .
Bilevel positive airway pressure (BiPAP) with a 2-tube system and viral filter, or 100% FiO2 nonrebreather mask may also be used for a proper oxygenation .
During HFNC procedure, the patient should wear a surgical mask . It must be kept in mind that Hudson and Venturi masks, nasal cannula and helmets, carry a lower risk of transmission when compared with high- flow nasal oxygen and NIV with facemasks or hoods . For preoxygenation, a 100% nonbreather mask for 3–5 min is used. Bag mask ventilation should be administered when necessary since it increases the risk for crossinfection. NIV should not be chosen as a preoxygenation method but if the patient is already on NIV, it should be continued .
Target oxygen saturation in preoxygenation should be 90–92%. Anything applied to the face or trachea such as mask or tube must have a viral filter. It is reasonable not to perform intubation on an awake patient. To ensure patient and provider safety, the procedure may be prolonged. Anytime the bag-valve-mask is squeezed, the risk of aerosolization increases . Avoiding HFNO, establishing conscious sedation with remifentanil before commencing airway topicalisation and avoiding transtracheal local anaesthetic infiltration are also measures that must be taken during intubation . In another study, accordingly, it was reported that the use of HFNO therapies or NIV has the potential to spread the virus, so they were not recommended. In the disease progression, it is more reasonable to intubate the patient with COVID-19 to intubate in the early stage . Preoxygenation should be optimised and bag mask ventilation should be avoided. If manual bagging is mandatory, a gentle ventilation via a supraglottic device instead of bag mask ventilation is suggested .
Rapid sequence induction (RSI) is the gold standard in patients with COVID-19 [26,27]. RSI combined with video laryngoscopy (VL) is even highly recommended . Following preoxygenation, modified RSI should be preferred for anaesthesia induction. For patients with anxiety, midazolam 1–2 mg may be administered. Also, lidocaine, 1.5 mg/kg or more, may be useful for suppressing coughing during intubation. In induction, etomidate for unstable patients and propofol for stable patients are recommended . Patients with COVID-19 must be under full neuromuscular blockade when intubation is needed .
In RSI medication, etomidate (0.2–0.3 mg/kg) can be used in hemodynamically unstable patients or propofol can be used as induction in hemodynamically stable patients. Short-acting opioids such as fentanyl may induce coughing. Other induction agents include ketamine and methohexital. Muscle relaxation is achieved by either rocuronium (1.2 mg/kg) or succinylcholine (1.0–1.5 mg/kg) . The reason for why rocuronium is preferred over suxamethonium is its longer half-life and its protective properties from coughing and vomiting. Chang et al. also recommend rocuronium with an IV dose of 1–2 mg/kg at a similar onset time to suxamethonium .
Midazolam has fewer cardiovascular side effects and it is a strong amnesic agent. In a study with 202 COVID-19 patients, a combination of etomidate or ketamine with low-dose midazolam was recommended. Prophylactic cardiovascular-stimulating agents must be ready to use at the time of ETI to minimise hypotension. Due to its rapid onset of action, Rocuronium, instead of succinylcholine, was also recommended as a neuromuscular blocking agent. When compared to succinylcholine, rocuronium also reduces coughing in case the intubation is prolonged . Due to the nature of coronaviruses, cough is one of the major ways of human-to-human spread. In the airway management interventions, any airway instrumentation can exacerbate coughing. Fentanyl may cause coughing following premedication with fentanyl (given prior to induction of anaesthesia) and can be prevented by a single intravenous dose of lidocaine. Lidocaine is proposed at the beginning and the end of any procedure requiring intubation and/or extubation in patients with COVID- 19 .
Respiratory distress develops in about 14% of the patients with COVID-19 . In another study, the rate of Acute respiratory distress syndrome (ARDS) was found to be 20% in hospitalized patients and 61% in patients admitted to the intensive care unit (ICU) . According to Benjamin etal., use of The King LT(S)-D laryngeal tube (King Systems, Noblesville, IN) extraglottic device, used in combination with administration of a highdose paralytic medication also reduces coughing . The use of a bougie during intubation may cause tracheal trauma and worsen the respiratory condition. When glottis is not visible, careful use of bougie is mandatory . Making the decision to whether to proceed with intubation or performing invasive ventilation in patients with COVID-19 who suffer acute hypoxemic respiratory failure remains as a challenging issue. The Chinese Society of Anesthesiology Task Force on Airway Management recommends recommendation to proceed with ETI for patients showing no improvement in respiratory distress, tachypnea (respiratory rate greater than 30 per minute), and poor oxygenation (Pao2 to Fio2 ratio less than 150 mmHg) after 2-h high flow oxygen therapy or NIV . With holding intubation has the risk of cross-infection in patients and also carries a risk to healthcare providers .
It is also recommended that intubation and ventilation should be performed by emergency physicians and anaesthesiologists . In a study in the USA by Aziz et al., it was reported that a team of anesthesiologists was constituted for intubation . Since it is essential to minimize the distance between the patient and the healthcare provider, VL rather than direct laryngoscopy must be preferred in patients with COVID-19 . In a study by Schumacher et al., the shortest time intubation was achieved by VL . In case it is inevitable to perform the intubation with direct laryngoscopy, it should be perfor med as soon as possible by the most experienced team member. Additionally, confirmation of the place of the tube and the quality of the CPR must be done by exhaust carbon dioxide detectors . In order to minimize aerosol spread, besides use of VL, usage of personal protective equipment (PPE) is highly recommended. When possible, a closed system with the HEPA filter already attached to the ETT via either the HEPA-ETT (‘HE’) or ‘Swivel-HEPA-ETT (SHE)- bougie’ methods may help to prevent healthcare providers from droplets originating from the larynx and trachea. Also, the ventilator may be attached to the HEPA filter following intubation [41–43]. It was reported that, early after the intubation, patients who were positioned prone developed a lower rate of pneumothorax following ARDS .
As mentioned above, rapid-sequence fibreoptic bronchoscopic ETI in COVID-19 pneumonia patients reduces the risk of coughing and subsequently viral spread when compared to laryngoscopy. Besides, neuromuscular blocking agents may also eliminate the risk of coughing when intubation with laryngoscopy is inevitable . When intubation with fiberoptic laryngoscope is performed, the controller should be held vertically above the airway in order to maintain the distance between the perfor mer and the patient. If the device is stabilised with the hand over the nose or mouthdareas, virus may transmit easily . It is also known that fibreoptic intubation needs skill and is timeconsuming so that after two failed attempts, the use of fibreoptic intubation only through a second-generation intubating supraglottic airway device is suggested .
The pattern of ventilation should be monitored by a continuous waveform capnography monitoring device since a correct waveform accurately reflects correct ETT placement. It might give clues on the adequacy of the seal when using supraglottic devices .
Airway management of patients with COVID-19 should be performed in a separate area near the ambulance entrance. In this area, the number of staff must be minimised in order to reduce virus spread. The team should be constituted of Emergency physicians or anaesthesists, or a mixture of these specialities. A tent covering the head and the chest of the patient may be constructed for intubation. The most skilled and experienced member of the team must perform the procedure as soon as possible. High-flow nasal oxygenation in critically ill patients not only provides a decrease in intubation time it also causes a less frequent incidence of desaturation during the procedure however, at the other hand, HFNO may cause consumption of limited sources. Anything applied to the face or trachea such as mask or tube must have a viral filter. RSI combined with VL is even highly recommended. In RSI, rocuronium should be the choice as an agent.
Authors declare no funding.
Author contributions: A.K.E. contributed in designing, writing, literature review, English editing and supervision. S.K. contributed in literature review. M.Ç. contributed in literature review. A.B. contributed in literature review, English editing and critical review.
Conflicts of interest
There are no conflicts of interest.
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