Discussion:
Anuwong (8) introduced transoral endoscopic surgery using conventional
laparoscopic instruments via oral vestibule, through premandibular space
with CO2 insufflation. First they used this approach in thyroidectomy
patients (Transoral endoscopic thyroidectomy by vestibular
approach:TOETVA). They reported that, TOETVA is safe and feasible,
resulting in no visible scar thus ideal method for cosmetic results. In
2016, Sasanakietkul T, Jitpratoom P and Anuwong A [2] adapted
Anuwong’s technique, which he introduced for TOETVA, to parathyroid
surgery (primary hyperparatyrisidism or renal hyperparatyrisidism) using
the inferior lip (Transoral endoscopic parathyroidectomy by vestibular
approach:TOEPVA). They reported excellent cosmetic outcomes with
feasible and safe surgical option.
While advances in surgical technique have been continued in parathyroid
surgery, we have not been able to find recommendations regarding the
anesthesia management of these cases in the literature. Up to date,
there is no report is published about how we can manage these patients
under general anaesthesia. Therefore, we want to share our anesthesia
management in TOEPVA in the literature.
Transoral surgery can be considered as having three important stages in
terms of anesthesia management. 1. Hydrodissection 2. Insufflations and
3. Surgical phase. While hydrodissection phase may cause an increase in
sympathetic activity by diluated epinephrine solution used for
hydrodissection; neck insufflations by carbon dioxide may cause sudden
suppression of sympathetic activity. During the surgical phase, due to
the surgical technique applied, absolute immobility of the case is very
necesssary for anaesthetist and surgeon, to avoid serious events. The
most important complications in surgical phase are pneumomediastinum
and/or pneumothorax and recurrent laryngeal nerve injury which requires
close capnography monitorisation and respiratuar follow-up respectively
[9].
For the best management of all the phases that mentioned above, we
preferred balanced anaesthesia (inhalation anaesthesia with opioid) in
our anaesthesia management in TOEPVA. We preferred desflurane as
inhalation anaesthetic; remientanil as opioid and rocuronium bromide as
neuromuscular blocker. All patients were reversed by sugammadex and
extubated at the end of the surgery. So in this article we want to
explain why we preferred these agents in our anaesthesia management in
TOEPVA.
Desflurane is a relatively new volatile anaesthetic, that have a low
blood-gas solubility resulting in rapid uptake and elimination [10].
Its muscle-gas partition coefficient is lower than other volatile
anaesthetics [11]. The enhancement of the neuromuscular blocking
effects of muscle relaxants (both benzylisoquinoline and aminosteroid)
by volatile anaesthetics is well known [11-13] and this phenomenon
is called as “Potentiation” (10). Rocuronium bromide is a
monoquaternary, aminosteroid, non-depolarising muscle relaxant with
rapid onset and intermediate duration of action [10,13]. Sugammadex
is a modified ɣ-cylodextrin developed for reversal of neuromuscular
blockade induced by aminosteroid neuromuscular blocking agents,
particularly rocuronium by formatting a complex with rocuronium
(encapsulation). Previous meta-analysis results reported that sugammadex
is superior to neostigmine, as it reverses neuromuscular block faster
and more reliable and accelerates postoperative discharge of patients
after general anaesthesia [14,15].
Wulf and colleagues [10] reported that neuromuscular blocking effect
of rocuronium to be enhanced by sevoflurane and desflurane, compared
with total intravenous anesthesia (TIVA) (propofol/fentanil). Bock and
et [12] showed that there was a marked interaction between
neuromuscular blocking effects of rocuronium and isoflurane, desflurane
and sevoflurane, compared with propofol. Maidatsi et al [11]
reported that desflurane anaesthesia significantly prolongs the duration
of action of rocuronium, compared to sevoflurane or propofol anaesthesia
in anaesthesia maintainance regimens. Although in vitro studies propofol
has been reported to potentiate the effects of neuromuscular blockers;
there is no report to date that propofol can clinically potentiate the
the effects of neuromuscular blockers clinically [13].
While neuromuscular blockade should be intense peroperatively because of
the nature of the surgery; maintainance of the airway patency must be
supplied at the end of the surgery. So we preferred rocuronium as a
neuromuscular agent, which has a specific and reliable reversal agent to
manage airway patency uneventfully after extubation and desflurane as an
inhalation agent, which enhances the neuromuscular block effect of
rocuronium peroperativelly.
It is important to measure intraoperative PTH level to verify the
removal of pathological parathyroid adenoma. PTH has a short half-time
and rapid metabolic clearance rate and has a rapid assay. But on the
other hand, PTH level influenced by some many factors including stress,
stress hormones (such as catecholamines, cortisol and inulin), general
anesthesia and endotracheal intubation (the most stress-baring
procedure), calcium, magnesium, vitamin D, anesthetic agents (propofol)
and laparoscopic surgeries (elevated blood CO2 may
change blood pH and cause a shift of ionized calcium [15,16]. Also
previous studies reported that propofol influence PTH level; Kivela et
al results suggests that there is no need to avoid propofol during
parathyroid surgery as previously suggested [16]. Whether propofol
affects PTH level or not is still debate so we prefer inhalation
anesthesia and desflurane as inhalation anaesthetic. We preferred
propofol only during induction to prevent hemodynamic alternations to
stress response and to suppress upper airway reflexes for nasal
intubation.But Bacuzzi et al [9] suggest total intravenous
anesthesia (bolus dose of propofol (2 mg/kg) followed by infusion
(0.2–0.5 γ/kg/min) of remifentanil) for transoral approaches.
Opioids have an important influence on upper airway events, purposeful
movements during surgery and recovery time [18], the requirements
for propofol or volatile anaesthetics [18,19]. Remifentanil has
rapid onset, short duration of action [18-20], great intraoperative
analgesia [19-21], quick recovery time [19-21], excellent
controllability [18] and metabolized by non-spesific esterase so
elimination is independent from liver and renal [18,19]. But
over-administered opioid analgesics during surgery delay recovery from
anaesthesia and cause opioid related side effects [19,20].
Ryu et al [20] compared intraoperative remifentanil requirements
during equi-Minimum Alveolar Concentration (MAC) anesthesia of 1 MAC
sevoflurane and desflurane anaesthesia via surgical pleth index-guided
remifentanil administration. They reported that intraoperative
remifentanil consumption was significantly lower in desflurane group
than sevoflurane group. Kowark and colleagues [18] shown that in the
presence of a continous infusion of remifentanil, desflurane is
significantly superior than sevoflurane and propofol in terms of
emergence from anaesthesia. Fukunaga et al [22] and Nooh et al
[19] showed same results. Remifentanil provides effective
suppression of cardiovascular responses to surgical stimulation and
promotes hemodynamic stability and improves recovery profiles.
We preferred remifentanil infusion as opioid analgesic to manage
sempatic activity changes during hydrodissection and insufflations phase
of anaesthesia in our anaesthesia management because of its best
pharmacokinetics and pharmacodynamics properties. And also we believe
that we lower intraoperative remifentanil consumption, avoid over
administered opioid side effects and better emergenced from anaesthesia
as Kowark et reported ,by combining remifentanil with desflurane.
Some concerns exist regarding the safety of neck insufflations by carbon
dioxide since then severe hypercapnia, acidosis, massive subcutaneous
emphysema and tachycardia was observed [23,24]. Bellantone et al
reported that carbon dioxide neck insufflations is safe ≤10 mmHg but use
of insufflations pressures higher than >15 mmHg should be
avoided to prevent metabolic and hemodynamic complications [24].
Rubino et al [23] reported that carbon dioxide neck insufflation up
to 10 mmHg does not alter intracranial pressure and is recommended for
clinical application in endoscopic neck surgery. The important issues
during neck insufflation are insufflation pressure and the rate of
insufflation. The head and neck region is dense in terms of the vessel
and nerve packs. Carbon dioxide neck insufflations may cause negative
haemodynamic effects by compressing these packs. We must take care
(atropine, ephedrine, adrenaline, large vessel, close communication with
surgeon for urgent desufflation etc) during insufflation phase of
surgery.
On the other hand, PTH itself causes alterations in vasodilatory
properties of endothelium by hypercalcemia which leads to short QT
intervals, prolongation of PR and QRS intervals and myocardial
depression [25]. Therefore, we should follow ECG changes and
hemodynamic parameteres more closely during anesthesia induction,
hydrodissection and insufflation.
We does not prefer N2O in laparoscopic surgeries in our clinical
practice. In addition, N2O increases postoperative nausea and vomiting
[9,21] which is a drug side effect that we do not want to encounter
in patients with TOEPVA, not to met with any infection postoperatively.
Conclusion: This is the first study which describe the
anesthetic management for TOEPVA in the literature. After induction of
anaesthesia with propofol, remifentanil and rocuronium; anesthesia
management by desflurane co-administered with continous infusion of
remifentanil, provide feasible and safe anaesthesia for TOEPVA. However,
especially during hydrodissection and insufflation, a close cooperation
between surgeon and anaesthetist have a great value to improve patient
management.Further studies are needed on anesthesia management for
TOEPVA in clinical practice.
Conflict of interest/Funding disclosure statements
Fulya YILMAZ and Koray BAS have no conflicts of interest or financial
ties to disclose.