ABSTRACT
VSE in our unit has also been assessed for the establishment of the CPAP level and has proven to be of great promise as an efficient and cost-effective means of CPAP titration.
3. THE PROCEDURE OF VSE
Patients who are surgical candidates are admitted as a day case. An intravenous site is established for access during the procedure. The patient is monitored for transcutaneous oxygen saturation, ECG, and blood pressure. Simultaneous PSG with EEG monitoring is at present used in our unit for research purposes. The sleep endoscopy laboratory is equipped with oxygen, suction, a conveniently adjustable BIPAP/ CPAP machine, and the standard resuscitation equipment. The more patent nostril is selected and 10% Xylocaine spray is delivered to the nasal cavity as well as the nasopharynx using a long cannula. An awake flexible nasopharyngoscopy is performed to exclude static obstructive lesion. A Muller maneuver is performed for correlation. Four milligrams of Midazolam is given as an induction bolus with saline flush. The light is dimmed and the patient is encouraged to sleep. The dose is increased 1mg at a time with saline flush until the patient sleeps. A minimal 5min wait is recommended after the first bolus and between increments. Increments are only needed if the patient shows no sign of sleep onset. The ceiling dose in our unit is limited at 7.5mg i.v., after which the patient is deemed to have failed sedation. The average dose in our experience is 0.06 mg/kg in OSAS cases. The dose for snorers is variable and we have applied the same ceiling dose of 7.5mg for this group of patients. Once the patient has slept, obstructive episodes are observed and the endoscopic examination is carried out after at least two episodes or cycles of obstruction and arousal. If the SaO2 should fall below 70%, the CPAP mask is applied and examination is resumed after 5min of unobstructed breathing. The endoscopic examination is performed using an Olympus P4 flexible nasopharyngoscope inserted via the anaesthetized nostril. In the location of obstructive sites, attention is paid to the following levels:
Soft palate Lateral pharyngeal wall Tonsils Base of the tongue Epiglottis Hypopharynx (the pyriform fossae squashing in around the larynx)
Once the level/levels of obstruction are established, the patient is reversed with the slow injection of flumazenil (Anexate) IV (300-500 mcg). It is important to be aware that the mean elimination half-life of flumazenil which is 35.5min is shorter than that of midazolam which is 107min. It, nevertheless, helps to shorten the duration of sedation. The patient is then turned on his side and airway monitored in our recovery area and then in the high dependency area of our ward.
