Author: Michael Vlessides
As the United States continues to grapple with the reality of the COVID-19 outbreak, anesthesiologists are finding that access to relevant and reliable information is key to maintaining personal safety and patient well-being. Nowhere is information more relevant than that coming from Chinese colleagues who have already weathered the worst part of the outbreak.
For Evan D. Kharasch, MD, PhD, the editor-in-chief of Anesthesiology, the decision to publish the articles online—well before they will appear in print in the journal—was easy. “COVID-19 is a disease of international scope; the proportions are unprecedented in our careers and our lifetimes,” he told Anesthesiology News. “So the journal made the decision to publish these articles as quickly as possible to be of greatest service to patients and practitioners, to get them this needed and valuable information as fast as we possibly could.”
Although slow to respond to the outbreak at first (see callout), China is seemingly over the worst of it, and the country’s clinicians have had a brief opportunity to reflect on lessons they’ve learned to date. Of these, they noted that it is important to remember the risk for aerosolized virus transmission to anesthesiologists is of particular concern. As such, it is critical for anesthesia providers to take personal protective measures when caring for patients.
The anesthesiologists also stressed the importance of coordinated efforts and clear regulations. Hospital administrators need to plan ahead, manage patient flow and minimize staff burnout. Meanwhile, department heads cannot lose focus on their employees’ mental health during these trying times.
“We realize that there is a lack of well-designed and executed studies to support these recommendations,” they wrote. “However, these recommendations are based on the experience of the frontline healthcare workers who have observed its effectiveness.”
In addition to explaining the pathogenic and epidemiological characteristics of COVID-19, the guidelines also offer specific perioperative precautions for physicians caring for patients with suspected or confirmed disease, beginning with the preoperative anesthesia clinic. Here, they recommend the use of personal protective equipment (PPE), including eye protection shields, surgical masks, or N95 masks or respirators. Preoperative evaluation should also include:
- single-patient entry to minimize contact;
- measurement of patient body temperature prior to entering the clinic room. Patients whose temperature exceeds 37.3°C should be escorted to a dedicated clinic for fever disorders and reported to an infection-control officer;
- detailed history and thorough physical examination, particularly chest examination;
- vigorous hand hygiene after each patient contact;
- immediate reporting of suspected cases to relevant infection control personnel; and
- cleaning and disinfection procedures appropriate for COVID-19 at the end of each shift, including furniture, equipment and floors.
The guidelines also discuss patient preparation for emergency surgeries, and recommend that individuals requiring such procedures undergo primary triage before hospital admission. A secondary triage before entering the OR can be performed by anesthesiologists, including medical history, body temperature, physical examination and chest imaging. If COVID-19 is suspected or confirmed, nonemergency surgical procedures should be canceled or postponed; patients requiring emergency procedures should be placed in isolation and transferred to a COVID-19 dedicated OR. Finally, patients with suspected or confirmed virus infection who are identified in a nondedicated hospital for COVID-19 should be reported and transferred, as possible.
Dedicated OR Recommended
Next, the recommendations offer guidance on anesthesia management in a dedicated OR, beginning with preoperative preparation. In addition to PPE for all clinicians, the guidelines recommend:
- A dedicated OR should be reserved for patients with COVID-19, labeled as such, and restricted to personnel involved in direct care.
- The in-room anesthesia care team should notify relevant officials that a COVID-19?positive patient is to be transferred to the OR.
- The OR and anteroom should be equipped with a negative pressure system. If such rooms are unavailable, the positive pressure system and air conditioning must be turned off.
- An anesthesia machine should be reserved for the dedicated OR.
- An artificial breathing circuit filter must be installed between the proximal end of the endotracheal tube and the distal end of the circuit. It is recommended to replace the filter after every three to four hours of anesthesia use.
With respect to anesthesia management, general anesthesia is recommended for patients with suspected or confirmed COVID-19 to reduce the risk of coughing or bucking. Nonintubated patients should wear a surgical mask or N95 mask throughout their OR stay. Spinal anesthesia is recommended as the primary anesthetic for cesarean delivery in infected women, who must wear an appropriate mask at all times. If supplemental oxygen is needed, the oxygen mask should be applied over the protective mask.
For induction of general anesthesia, the guidelines recommend rapid sequence induction. They also urged that the patient’s nose and mouth be covered with two layers of wet gauze during preoxygenation, after which they should be covered by the anesthesia mask. Sufficient muscle relaxation also should be used to prevent coughing during intubation. In these cases, oral intubation with a video laryngoscope, bronchoscope or fiberscope is preferred. A closed airway suction system is recommended to minimize viral aerosol production.
When recovering from anesthesia, patients with COVID-19 should bypass the PACU and be sent directly to an ICU-based isolation room. Extubation should take place in the OR; prior to extubation, the patient’s nose and mouth should be covered with two layers of wet gauze.
The guidelines also consider patient transfer, recommending that suspected or confirmed infected patients who do not qualify for ICU admission be transferred directly back to a negative-pressure ward or isolation ward after extubation. During transfer, the circulating nurse and anesthesiologist should wear proper PPE, while the patient is covered with a disposable operating sheet and moved via a dedicated lobby and elevator. Patients must wear an appropriate mask during transfer; surfaces of passageways and the elevator should be cleaned and covered afterward. For intubated patients, a single-use Ambu bag should be used during transfer; ventilators should not be used during transfers.
Finally, the guidelines take a close look at the care of PACU equipment and medical waste. With respect to anesthesia equipment care and OR disinfection, they recommend that all anesthesia equipment, supplies and medications—including anything that touches the patient’s skin or mucosa—be used for one patient only. All anesthesia equipment should be cleaned and disinfected promptly; the carbon dioxide absorber should also be replaced between cases. The respiratory circuit within the anesthesia machine should be disinfected between cases and at the end of the shift.
Medical waste needs to be considered, and should be sorted and disposed of immediately after use. All relevant waste should be double-bagged and labeled “COVID-19.” Before being removed from the contaminated area, bags should be sealed and sprayed with disinfectant, or covered with an additional bag and sealed. Clinicians involved in the surgery should place their PPE in a designated waste bag in an anteroom. Nondisposable PPE can be packed into medical waste bags and placed in a designated area.
Notably, the guidelines do not omit surveillance of anesthesia providers after caring for patients with confirmed or suspected COVID-19. Here, they recommend that practitioners who had direct contact with such patients and go on to develop fever, cough or fatigue must inform their institution’s administration. This should be followed by complete blood tests and computed tomography of the chest.
Intubation, Ventilation Present Distinct Challenges
Although the task force’s recommendations also address practice patterns during intubation and ventilation, these were discussed in detail in another article in the Anesthesiology series, “Intubation and Ventilation amid the COVID-19 Outbreak.” In the experience of Lingzhong Meng, MD, and colleagues, the demand for intubation and invasive ventilation is intense. Indeed, the researchers estimated that approximately 3.2% of all infected patients in China received such treatment.
As the authors explained, the decision to intubate an infected patient can be obvious, but is also one that lacks quality evidence. Nevertheless, anesthesiologists caring for patients in Wuhan suggested that intubation and ventilation may have been adversely delayed in some patients, and was used more as a salvage therapy than as a means of supporting individuals with progressively worsening respiratory function.
They suggested that for patients with acute hypoxemic respiratory failure due to COVID-19, intubation should be performed in those who show no improvement in respiratory distress, tachypnea and poor oxygenation after two hours of high-flow oxygen therapy or noninvasive ventilation.
The authors also urged their fellow anesthesia providers to protect themselves during intubation and ventilation because of the enhanced risk for cross-infection. Clearly, this involves the use of approved PPE, which the researchers suggested be donned and doffed in a predictable order. They also explained that all inadvertent contamination of the skin or mucosa be reported, to assess the need for possible quarantine. Use of oral, nasal and external auditory canal disinfectants is recommended after the removal of PPE.
Intubation and Extubation
Regarding intubating and extubating patients who may have COVID-19, preparation is key to minimizing the chance of cross-infection and improving the odds of an uneventful intubation. The approach proposed by the researchers uses the acronym OH-MS MAID, which reminds clinicians to have adequate supplies (and back-up) of oxygen, helpers, monitors, suction, anesthesia machines, airway supplies, intravenous access and drugs.
Most infected individuals in Wuhan were on either high-flow oxygen therapy or bilevel positive airway pressure ventilation when intubation was called for. For patients on high-flow oxygen therapy, clinicians should consider a bag-valve mask or tightly fitting face mask connected to a ventilator for preoxygenation. If the patient is on a bilevel positive airway pressure machine, this should be continued for preoxygenation, and oxygen flow should be increased to 100% FiO2 to maximize oxygenation.
Clinicians should ensure the airway is patent, and an oral or nasal airway applied at the first sign of difficult masking. If preoxygenation fails to improve oxygenation, the authors advised clinicians to consider manual positive pressure ventilation using a bag-valve mask.
“Although the aerosol-generating potential of noninvasive ventilation is a potential concern to some providers,” the authors wrote, “the bilevel positive airway pressure machine is widely used amid this outbreak for patients with acute hypoxemic respiratory failure in Wuhan and the rest of China.”
Following satisfactory preoxygenation, modified rapid sequence induction is recommended for induction. Ventilation should continue throughout induction through a patent airway and using a small tidal volume, until the patient is intubated.
Since a patient coughing during intubation can put providers at risk, the authors suggested gentle airway manipulation, as needed. Video laryngoscopy is preferable to direct laryngoscopy since it increases the distance between the clinician’s and patient’s faces. Chest auscultation following intubation was not routinely performed in Wuhan given concerns of contamination. The same precautions should be considered during extubation.
Although guidelines are currently lacking with respect to ventilation management in critically ill COVID-19 patients, the authors advised adoption of guidelines for patients with ARDS, with relevant modifications based on the Wuhan experience. These guidelines emphasize four variables:
- Tidal volume of 6 mL/kg or less of predicted body weight
- Respiratory rate of 35 breaths per minute or less
- Plateau airway pressure of 30 cm H2O or lower
- Positive end-expiratory pressure of 5 cm H2O or higher
Although no mode of ventilation has been suggested to be superior to others, high-frequency oscillatory ventilation may result in aerosol generation and should be avoided.
The guidelines also recommend ventilation in the prone position, which may improve lung mechanics and gas exchange. Although lung recruitment maneuvers may improve oxygenation, such maneuvers are not supported by high-quality evidence. The researchers also cautioned against their use since they can provoke coughing and generate aerosols.
Adjunct therapies have been considered in infected patients. Muscle relaxants may improve oxygenation and should be considered in cases of breathing overdrive, patient?ventilator dyssynchrony, and inability to achieve the targeted tidal volume and plateau pressure. Conservative fluid therapy has been commonly used in Wuhan. Corticosteroid treatment is largely avoided, although it is used in selected patients with severe inflammatory lung injury.
The researchers also recommended the use of in-line catheters for airway suctioning and endotracheal tube clamping before disconnecting breathing circuits. Extracorporeal membrane oxygenation has been used successfully in patients with severe influenza, and was used in some critically ill patients with COVID-19 in Wuhan.
“How to provide the best practices of intubation and ventilation amid this mass medical emergency is a real but unprecedented question,” the authors concluded. “In patients with acute refractory hypoxemic respiratory failure, timely, but not premature, intubation and invasive ventilation support may be superior to high-flow oxygen therapy and bilevel positive airway pressure ventilation in boosting transpulmonary pressure, opening collapsed alveoli, improving oxygenation, decreasing oxygen debt, and offering a better chance for the lungs to heal.”
Vital Lessons From Wuhan
For Dr. Kharasch, the coronavirus experience highlights multiple lessons that anesthesiologists can take away. “It is very difficult to single out just one lesson that’s more important than the others,” he said. “I think it is the degree of contagion and communicability of this particular virus. It is the speed with which patients can decompensate. It is the need for strict infection control, for protecting patients from cross-contamination, and for protecting practitioners from acquiring the virus.
“It is also the degree of stresses that this pandemic is putting on systems that have been working largely at capacity,” he added. “And now somehow we’ll have to, without the resources, accommodate the surge that we are facing and will continue to face.”
Yet, like his fellow anesthesiologists across the country, Dr. Kharasch recognizes that safety is a personal and institutional matter. “I’m protecting myself by listening to the experts and heeding their advice and heeding local and national requirements,” he said. “I’m practicing assiduous hand washing. I’m very careful when I’m in the operating room to practice hand washing and hand disinfections between every room and every patient contact.
“And I’m now actively thinking about the things we usually do on a daily basis without normally thinking about them, to try and minimize the risk that I may pose to myself, or my family, or the patients I’m taking care of.”