3 | DISCUSSION
SWS is characterized by angiomas involving the brain, face, and eye. The
rupture of angiomas may result in uncontrolled hemorrhage and may be
fatal. Therefore, the rupture of
angiomas should be avoided in anesthetic management.
In this case, mask ventilation was difficult because his upper lip was
markedly swollen and protruded due to angiomas. Therefore, we checked
mask fitting and prepared a large mask and total-face mask, which is
often used for noninvasive positive pressure ventilation therapy. We
could perform mask ventilation with a large mask. However, we needed to
use an oral airway, which could cause pressure on the swollen upper lip.
The pressure on the lip might cause the rupture of angiomas. Therefore,
we changed to a total-face mask for mask ventilation. The total-face
mask allowed us to perform mask ventilation without an oral airway and
avoid pressure on the lip.
Generally, airway management is performed with nasal intubation in SSRO
because surgeons should check the bite during surgery. However, in this
case, the otolaryngologist suggested avoiding nasal intubation because
of the angiomatosis in the nasal cavity and the remarkable bony
thickening of the inferior nasal dorsum. In such a case, tracheostomy is
an alternative option. However, tracheotomy is associated with various
complications and should be avoided whenever
possible.10 Thus, SMI is another option. SMI is an
alternative to tracheotomy11 and has been used in
patients with severe maxillofacial trauma. Although SMI was applied in
orthognathic surgery, the application of SMI to patients with SWS has
not been reported. SMI can cause
complications such as superficial infection of the submental wound,
orocutaneous fistula, abscess formation, and hypertrophic scarring.
However, these complications are rare.12 Fortunately,
no angiomas were found in the submental region by magnetic resonance
imaging in this case. Therefore, we decided to perform airway management
with SMI during surgery. When we pulled the ETT from the floor of the
mouth, we placed a sterilized echo probe cover over the ETT to let it go
through smoothly because we could not remove the connector of the
wire-reinforced tube in our institution. This method helped mitigate
bumps on the connector of the ETT to avoid tissue damage and infection
and prevent blood from entering the ETT. Goh et al. reported that damage
to the tube apparatus is one of the most common complications of
SMI.13 This method also helped to avoid damage to the
pilot balloon because the sterilized echo probe cover prevented it from
directly gripping.
Blood pressure should be controlled to avoid the rupture of angiomas.
Therefore, the depth of anesthesia was monitored using an entropy
monitor. This is an electroencephalography-based monitor for determining
hypnotic and analgesic levels. In this case, this monitor showed that
state entropy (SE) and response entropy (RE) varied from 40 to 60 during
anesthesia. The recommended range for adequate depth of anesthesia
regarding each parameter (SE or RE) is 40–60.14Therefore, anesthetics appeared to be administered adequately, and the
blood pressure was stable during surgery.
Maraña Pérez et al. reported that 46% of patients with SWS have mental
retardation.15 Low cognitive understanding and
intellectual disability can interfere with perioperative doctor-patient
communication, which causes mental stress, elevated blood pressure, and
swelling of angiomas.16 However, the patient’s
intellectual disability was borderline, and no communication problems
were noted. Therefore, we attempted to form a trusting relationship with
the patient through several preliminary examinations and detailed
explanations. Consequently, we did not prescribe premedication but
lidocaine tape to reduce stress as much as possible. These might help
maintain stable blood pressure.
Previous studies have reported that propofol can induce seizures in
patients with poorly controlled epilepsy. Our patient had a history of
epilepsy. However, he had no
seizures for more than 10 years without medication. In addition,
propofol has significant anticonvulsant effects and has been used to
manage status epilepticus.3 Our patient also had a
history of glaucoma. Therefore, we had to avoid raising intraocular
pressure (IOP) during surgery because high IOP could damage the optic
nerve and cause vision loss. Previous studies have reported that
propofol attenuates increased intraocular pressure.17,
18 In addition, propofol has been used in patients with SWS. Therefore,
we used propofol as an anesthetic in this case.