GAWA during COVID-19 pandemic: a setback?

The year of 2020 will undoubtedly be marked by the beginning of the SARS-CoV-2 pandemic which, by the risk of transmission via aerosols and droplets, demanded adjustments by all medical and surgical specialties, particularly Anesthesiology, by its presence in the so-called frontline.

In Portugal, the majority of patients are tested for SARS-CoV-2 (Reverse Transcription-Polymerase Chain Reaction SARS-CoV-2). However, since the test is not preceded by isolation, and given its low sensitivity (around 70%), precautions to minimize exposure are maintained despite a negative test result.

Thus, given the presented information, Regional Anesthesia is currently given preference – both Neuraxial and Peripheral – to General Anesthesia with the need for airway management. Airway management represents one of the moments of highest risk of transmission through generation of aerosols, hence requiring the use of Personal Protective Equipment (PPE) by all parties involved, as well as allowing for time of air renewal and hygienisation of the room. Both the optimization of the Operating Room times and the rational use of the PPEs are important factors to consider when finally returning to elective surgery.

However, there are some circumstances where general anesthesia cannot be avoided. The definition of general anesthesia, according to the American Society of Anesthesiologists (ASA),¹ which was reviewed in 2019, mandates for the loss of consciousness, with lack of response to painful stimuli which might be associated with: need for airway interventions in a way to keep its patency; possibility of inadequate spontaneous ventilation or neuromuscular depression with need of positive pressure ventilation; and eventual deterioration of cardiovascular function.

The following two clinical cases, both occurring during the pandemic, will present the use of general anesthesia without the need of airway management, named by some authors as General Anesthesia Without Airway (GAWA).² Once it is not a study, an institution’s Ethics Committee approval was not necessary. The patients were not selected, but rather the result of circumstances.

The first case is of a female, age 45, BMI 32 kg.m^-2, ASA II, with a non-detectable RT-PCR SARS-CoV-2 test result, diagnosis of unilateral bimalleolar fracture and proposed for ankle arthroscopy and osteosynthesis with tourniquet application above the knee. A spinal anesthesia was performed using levobupivacaine 10 mg and sufentanyl 2,5 mcg, with subsequent prone positioning of the patient for surgery. After 10 minutes, no sensitive, motor, or sympathetic block was accomplished. Due to failure of the spinal block and the patient being in prone position, we converted to general anesthesia, starting by applying an oxygen cannula with analysis of expired gases (Sentri™ ETCO2 nasal cannulae) with a flow of 3 L.min^-1, which allowed the patient to maintain her surgical mask. Induction was performed with intravascular ketamine 20 mg, fentanyl 100 mcg, and propofol perfusion using Target Controlled Infusion (TCI), Marsh model and target concentration of 3–4 mcg.mL^-1. The surgery lasted 2,5 hours with tourniquet duration of 108 minutes. Breathing was regular – without tachypnea or hypopnea – as was the capnography curve, and no increase in end-tidal carbon dioxide (EtCO2) was verified. Emergence time was not longer than that usually verified with airway management.

The second case refers to a female patient, 12 years old, BMI 17 kg.m^-2, ASA I, with a non-detectable RT-PCR SARS-CoV-2 test result, diagnosis of a volar ganglion cyst of the wrist, proposed for its excision. After a nasal oxygen cannula with analysis of expired gases (Sentri™ ETCO2 nasal cannulae) with a flow of 2 L.min^-1 and without the removal of the surgical mask, fentanyl 50 mcg was administered and a propofol perfusion was initiated using TCI, with a target concentration of 4–5 mcg.mL^-1. The surgery lasted 45 minutes. No hemodynamic or ventilatory compromise was observed, as well as no delay in emergence from anesthesia.

In this context, it is important to anticipate a scenario in which the patient loses spontaneous ventilation. The use of capnography, an ASA standard form of monitorization, should provide early detection of bradypnea or apnea, and guide the titration of anesthetic agents. If necessary, prompt airway management is essential and may be difficult when the patient is in the prone position, as presented in the first case. The presence of an anesthesiologist skilled in airway management in prone position is critical and quick access to a supraglottic device is essential. In extreme situations, this may require interruption of the procedure and repositioning of the patient in the supine form – which is why we always allow for an extra bed outside the operating room.

Patient selection is key for the success of GAWA. The technique should not be used in patients with increased risk for respiratory depression, those with sleep apnea, obesity, pulmonary disease and predicted difficult airway.³ Such precautions are common concerns in settings outside the operating room, as in endoscopic retrograde cholangiopancreatography, which often requires deep sedation bordering on general anesthesia with the patient in prone position.⁴ Emphasis must be placed on an open, multidisciplinary communication from the start of the procedure (e.g., to discuss anesthetic choice and safety concerns) through the application of the WHO Surgical Safety Checklist.

With the return to elective surgery in times of pandemic, considering inadequacy of regional anesthesia techniques or their failure, GAWA certainly presents advantages, particularly in short duration surgeries in which neuromuscular blockade is considered unnecessary. Simultaneously, considering the specifics of each case, this modality might both be used as a primary strategy as well as a rescue when regional anesthesia fails.

References

• ¹
  American Society of Anesthesiologists, Available at: https://www.asahq.org/standards-and-guidelines/continuum-of-depth-of-sedation-definition-of-general-anesthesia-and-levels-of-sedationanalgesia, 2019.
  » https://www.asahq.org/standards-and-guidelines/continuum-of-depth-of-sedation-definition-of-general-anesthesia-and-levels-of-sedationanalgesia
• ²
  Napoli V, Napol E, Parino E. General anesthesia with spontaneous ventilation without intubation for short-stay operations. Minerva Anestesiol. 2002;68:669-80.
• ³
  Hillman D, Platt P, Eastwood P. The upper airway during anaesthesia. Br J Anaesth. 2003;91:31-9.
• ⁴
  Walls J, Weiss M. Safety in Non-Operating Room Anesthesia (NORA). Anesthesia Patient Safety Foundation. 2019;34:3-4.

Publication Dates

• Publication in this collection
  24 May 2021
• Date of issue
  Mar-Apr 2021

History

• Received
  28 July 2020
• Accepted
  9 Dec 2020