Thoracic Anesthesia in the Coronavirus Disease 2019 (COVID-19) Era.

Coronavirus disease 2019 (COVID-19) is a potentially severe and highly contagious respiratory disease caused by infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It can be transmitted by respiratory droplets and direct contact, and both symptomatic and asymptomatic patients can be infective. Anesthesiologists, especially thoracic anesthesiologists, are at increased risk of exposure owing to direct contact with the trachea during intubation; bronchoscopy; airway suctioning before, during, and after one-lung ventilation (OLV); and during extubation in patients who may present with varying degrees of respiratory infection. In this issue of the Journal of Cardiothoracic and Vascular Anesthesia, Şentürk and the European Association of Cardiothoracic Anaesthesiology Thoracic Subspecialty Committee have developed preliminary recommendations for the airway management of thoracic surgical patients with suspected or confirmed SARS-CoV-2 infection.

SARS-CoV-2 is a member of a family of single-stranded RNA viruses that also includes the severe acute respiratory syndrome (SARS) and the Middle East respiratory system (MERS) coronaviruses, viruses that primarily target the human respiratory system. Clinically, SARS-CoV-2 targets the lower airway, producing upper respiratory tract symptoms such as rhinorrhea, sneezing, and sore throat, which can progress rapidly to pneumonia and acute respiratory distress syndrome. Unlike SARS or MERS, patients infected with SARS-CoV-2 also developed intestinal symptoms, such as diarrhea. Other typical signs include fever, dry cough, and dyspnea. Myocarditis and lymphopenia also can occur.

The initial appearance of SARS-CoV-2 occurred in December 2019, in Wuhan, Hubei Province, China, where a cluster of patients presented to the hospital with pneumonia. Five of these patients developed acute respiratory distress syndrome and by January 2, 2020, 41 patients had been diagnosed with SARS-CoV-2. By January 30, 2020, there were 7,734 cases confirmed in China and 90 others confirmed worldwide, including countries in Southeast Asia, the Middle East, the United States, and in Europe. Also, on this date the United States first reported a case of human-to-human transmission of SARS-CoV-2. Currently, there is no vaccine or specific therapy for the treatment of SARS-CoV-2. Treatments based on anecdotal evidence and preliminary clinical trials include the antivirals lopinavir/ritonavir, remdesivir, favipiravir, and tocilizumab and the anti-inflammatory and immunomodulatory agents tocilizumab, chloroquine, and hydroxychloroquine. Currently, remdesivir holds the most promise for treatment. By inhibiting viral RNA synthesis, it has been demonstrated to reduce the viral load and to prevent the replication of the SARS-CoV-2 virus.

The World Health Organization called the coronavirus outbreak a pandemic on March 11, 2020 with over 118,000 cases in over 110 countries. At present, there are more than 3 million cases globally, with over 250,000 deaths. In an attempt to protect anesthesia, surgical, and intraoperative personnel from contracting SARS-CoV-2 while providing care to these patients, consensus guidelines were developed by the Difficult Airway Society, the Association of Anaesthetists, the Intensive Care Society, the Faculty of Intensive Medicine, and the Royal College of Anaesthetists for the management of the airway in patients with SARS-CoV-2. Building on those recommendations, the European Association of Cardiothoracic Anaesthesiology Thoracic Subspecialty Committee has created preliminary recommendations using expert opinions that reviewed the clinical experience in patients with MERS-CoV and COVID-19 undergoing thoracic surgery; a literature search on the management of patients with MERS-CoV, COVID-19, SARS, and H1N1, including consensus recommendations, guidelines, randomized controlled trials, reviews, and observational and cases series; and through a limited survey of members of the subcommittee. These recommendations focus on the preparation for anesthesia, airway management, OLV, ventilation, and extubation.

The goals of these recommendations are to emphasize efficient airway control and to establish controlled ventilation without compromising the patient while providing maximal protection to the health care team. Tracheal intubation in COVID-19 patients is a high-risk procedure because of aerosol transmission during tracheal intubation either with a double-lumen tube (DLT) or endotracheal tube (ETT) with a bronchial blocker (BB), and during bronchoscopy to evaluate and manage the device. Intubation is also a risk for patients with severe lung disease due to COVID-19 who may not tolerate prolonged periods of apnea. The authors developed a mnemonic SAS, meaning that the procedure should be safe for the staff and patient, accurate, and swift. Because patients infected with SARS-CoV-2 may be asymptomatic, it is suggested that every patient be viewed as potentially infectious. Other recommendations are that elective intubations are preferable over emergency intubations, the intubation should occur in a negative pressure room with >12 air changes/min, the level of personal protection equipment (PPE) should include a respiratory type mask and face shield or helmet, and if the operating room (OR) does not have a negative-pressure room, the intubation should be performed in a negative-pressure room followed by transfer to the OR. In a positive-pressure room, the room should be placed under the least possible positive pressure with the door closed with the rest of the OR under higher positive pressure to limit the dispersion of aerosols. The intubating team should be limited to those with essential roles and should be the most experienced providers, one to manage the airway and the other to administer medications and to assist. Those not required for airway management should be outside of the room until the airway is secured. The operating room and immediate area are divided into 3 zones: the red zone, where the actual procedure takes place; a yellow zone, located outside of the operating room, where a physician with full PPE is available if help is required; and a white zone, outside of the OR, where an observer can monitor the donning and doffing of PPE. The authors also suggest different levels of PPE depending on the level of exposure. Procedures defined as having an increased risk of infection are the most aerosol-generating procedures, such as intubation and bronchoscopy. During these procedures, the authors suggest the use of airborne-level precautions including hair covers/hoods, a fitted filtering facepiece or N95 mask, goggles or face shield, long-sleeve fluid-resistant gowns, double gloves, and shoe covers, with a specific sequence for donning and doffing the PPE to avoid the spread of infection.

In preparation for intubation, it is recommended that a stand be set up with single-use blades, laryngoscopes, video laryngoscopes, and flexible bronchoscopes; a closed system for suction; ETTs; and devices for OLV, including BBs and DLTs. An antiviral filter should be attached to the expiratory limb of the circuit. Patient position should be optimized before intubation and the patient adequately preoxygenated to prevent or reduce the need for mask ventilation. If face mask ventilation is required, a 2-person, low-flow, low-pressure technique should be used, with a 2-handed grip on the face mask to improve the seal. A rapid-sequence induction should be performed. Intubation should be performed using videolaryngoscopy with a single-use blade and remote screen to minimize or avoid airborne spread of aerosolized secretions. The suggested algorithm for an unanticipated difficult intubation includes laryngoscopy with an ETT with a stylet, and if that attempt fails, oxygenation should be performed using a low tidal volume/low-pressure technique. If the second attempt at laryngoscopy fails, the use of a second-generation intubating supraglottic airway device should be considered with intubation through this device using fiberoptic bronchoscopy and a remote screen. The ETT cuff or tracheal cuff of the DLT should be inflated to seal the airway before initiating ventilation, and the cuff pressure should be at least 5 to 10 cmH2O above maximal airway pressure to minimize the risks for aerosol spread. The choice of device used for OLV varies on the indication, the difficulty of intubation, the length of the procedure, and whether postoperative ventilation is required. Bronchial blockers are recommended for patients where separation is required; for shorter procedures; and in patients with a potentially difficult airway, for those who arrive to the OR intubated, or when postoperative ventilation is anticipated. Double-lumen tubes are indicated for patients where lung isolation and suctioning are required or the use of continuous positive airway pressure (CPAP) is anticipated. If available, a DLT with an embedded camera can minimize the requirement for a bronchoscope and avoid opening the airway. For airway manipulations such bronchoscopy or airway suctioning, it is suggested that an ETT swivel connector with a valve that prevents leakage from the airway be used. Before opening the valve to introduce the bronchoscope or suction catheter, the anesthesia ventilator should be paused and the procedure performed under apnea.

In patients with a known history of difficult intubation, awake fiberoptic intubation should be avoided whenever possible and no aerosol or vaporization should be used for airway topicalization. If fiberoptic intubation is necessary, titrated sedation is recommended, with rescue intubation through a third-generation supraglottic airway or early cricothyroidotomy.

Once the ETT or DLT is connected to the breathing circuit, it should remain connected. A closed suction catheter with an infraglottic tip should be attached to the circuit to be used for suctioning. If disconnection from the breathing circuit is necessary, the ventilator should be switched to standby and the ETT should be clamped. After tracheal intubation, disposable equipment should be discarded, reusable equipment should be placed inside sheaths and decontaminated, and if the intubation room is separate from the OD, doffing of PPE should be performed and monitored by an observer. The room should be empty for 20 minutes before cleaning to allow aerosols to settle. In the operating room (OR), PPE should be worn until the end of the procedure, after immediately changing the outer gloves. Hand hygiene must be performed before and after all patient contact, and the risks of aerosol transmission with coughing and the need for reintubation should be weighed before attempting to extubate the patient. ,

Another recommendation is to avoid performing non-intubated thoracic surgery owing to the lack of data of performing these procedures on patients with highly contagious diseases and because the use of this procedure would leave the airway unsecured, increasing the risk of contagion. Except for the helmet, all types of noninvasive ventilation are associated with a risk of aerosol spread, and it is recommended that both noninvasive ventilation and high-flow nasal cannula be avoided in these patients.

Recommendations for OLV include the placement of another antiviral filter to the end of the lumen of the nondependent lung, which is disconnected during OLV, and protective ventilation with an inspired oxygen content of 1.0 and tidal volumes between 4 and 6 mL/kg of the predicted body weight, and because these patients may have compromised oxygenation at baseline and a higher incidence of hypoxia during OLV, a higher positive end-expiratory pressure (PEEP). A PEEP of 13 to 15 cmH2O may be required. A PEEP titration can be used to determine the optimum PEEP and if lung compliance is not affected, an alveolar recruitment maneuver may be helpful. The application of PEEP or recruitment maneuvers should be used with caution because they may impair hemodynamic stability. Oxygenation should not be compromised during procedures that do not require isolation. The authors suggest the use of CPAP to the non-dependent lung to prevent hypoxia where the benefits of oxygenation outweigh the possibility of aerosolization from the CPAP system.

When the procedure has ended, most patients with SARS-CoV2 will require postoperative mechanical ventilation. In procedures where a BB was used, it can be removed at the end of the surgery. If a DLT was used, it is suggested that it be exchanged for an ETT using a tube changer that is specific for DLTs with appropriate donning of PPE. If the period of postoperative ventilation is short or the patient who is being weaned has excessive retained secretions owing to the SARS-CoV2 virus, it is suggested that the two-lung ventilation with DLT continue until the patient meets the criteria for extubation.

In patients who are candidates for extubation, it is suggested that gentle oropharyngeal suction is performed using a closed system, followed by a recruitment maneuver. The patients should be able to extubate to a tightfitting facemask to prevent airflow into the OR environment and should be instructed not to cough. Patients with a known difficult airway should remain intubated. Medications that lower the incidence of coughing, such as dexmedetomidine, may be administered, and the use of an N95 or surgical mask on the patient’s face after extubation with an oxygen mask over it can prevent aerosolization while oxygenating the patient. After transferring the extubated patient, the PPE has to be doffed properly and the OR should be disinfected.

Although many of the recommendations that these authors have suggested are similar to those from other societies, the specific recommendations about the indications for BBs, performing all airway manipulations under apnea, the use of tightfitting valves during bronchoscopy, suctioning and device changes, as well as antiviral filters on the non-dependent lung will help to reduce the spread of infectious aerosols to keep the intraoperative team safe while they are taking care of these patients.

Conflict of Interest

None.