Discussion
General recommendations for difficult airway management are awake
fiberoptic intubation, awake video laryngoscope, laryngeal mask airway
as an intubating conduit, lightwand, oral or nasal blind intubation,
retrograde intubation, invasive airway access, and ECMO which is left as
the last method [9]. In this case, due
to the severe contractures and microstomia, direct visualization of the
pharynx and larynx by video laryngoscope seemed impossible. Laryngeal
mask airway was not considered because size # 3 or 4 for a female adult
is too large to pass through her mouth. Orotracheal intubation with
lightwand was excluded on the reason that neck scars cannot be
illuminated. Retrograde intubation and tracheostomy were also excluded
for the reason that anterior neck structures, including the larynx,
trachea, and carotid arteries, are unidentifiable and impalpable. For
the distortion of the upper airway and uncertainty of success, oral or
nasal blind intubation was not the preferred choice. Due to a good
safety and success profile, awake fiberoptic intubation is a preferred
choice of anticipated difficult tracheal intubation
[3]. However, ATI may give patients
significant discomfort and nociceptive recall
[10-12] or be perceived as
potentially dangerous when causing a pronounced sympathetic response
[13]. Furthermore, due to the several
failures of awake intubation in other medical centers, the patient
refused to accept it again. Therefore, fiberoptic intubation with
precise sedation, analgesia, and without inhibition of spontaneous
ventilation and cardiovascular function seems an ideal choice.
At present, many sedative drugs, such as midazolam, dexmedetomidine,
propofol, sevoflurane, can be selected. A low dose of midazolam produces
a direct amnesia effect. Dexmedetomidine provides a good sedative effect
in awake conditions, but the sedation needs to be carefully titrated as
excessive sedation can lead to hypoventilation and bradycardia, or
inadequate sedation leads to discomfort, anxiety and excessive
sympathetic discharge. Moreover, dexmedetomidine may cause nociceptive
recall [8,
14]. Compared with propofol intravenous
anesthesia, sevoflurane inhalational has less effect on respiratory
depression [13]. Moreover,
sevoflurane can be quickly washed out. Thus, it is more controllable
than other intravenous drugs. In this case, midazolam 2 mg, sufentanil 5
μg, and intermittent sevoflurane inhalation were administrated to
provide precise sedation and analgesia. Meanwhile, an oral hose was
connected to a high flow of oxygen to prevent hypoxia. However, sedation
should not be used as a substitute for inadequate airway topicalization
[3].
To sufficiently anesthetize the upper airway and suppress the gag,
swallow and cough reflexes, a perfect topicalization is essential. There
are many ways of airway topicalization, such as nebulization with
lidocaine, nerve block, thyrocricocentesis spraying, and the SAYGO
technique [2]. However, research
indicated that atomization of local anesthetics had a potential
possibility of higher stress responses and poisoning
[15]. Due to anatomical structure
changes, nerve block and thyrocricocentesis were impossible for such
kind of patients. Compared with the classical SAYGO technique that
lidocaine sprayed directly via the working channel of the fiberscope,
the modified SAYGO technique, which lidocaine sprayed via an epidural
catheter inserted through the working channel of the fiberscope,
controls the dosage of local anesthetics more accurately and does a
better anesthesia effect, therefore usually used in patients with
difficult airway [6-8]. However, the
epidural catheter does not match with all fiberscopes. Here, we directly
fastened the epidural catheter at the end of the fiberscope. Moreover,
this SAYGO technique can evaluate the airway passage directly, which
increases the safety of intubation. Thus, it seemed a better choice in
this case.
Furthermore, once the local anesthetics worked, the patient was sedated
by sevoflurane inhalation again, then intubated by the guidance of
flexible bronchoscopy. Taken together, using intermittent sevoflurane
inhalation and the modified SAYGO technique, a safe, comfortable,
unconscious,
and satisfied intubation with spontaneous breathing keeping was achieved
in a postburn patient with severe difficult airway and unwillingness to
accept ATI. Moreover, this strategy is not limit to postburn patients
with difficult airway.