A simplified anaesthesia procedure may enable more widespread use of preoperative testing to demonstrate the cause of airway obstruction in patients with severe sleep apnoea, according to a study published in the journal Anesthesia & Analgesia.
Researchers have developed a new “ramp control” anaesthetic technique for putting patients to sleep briefly-just enough to show the obstructive anatomy responsible for sleep apnoea. The simplified technique requires no special expertise and limits drops in blood oxygen level during testing.
Joshua H. Atkins, MD, and Jeff E. Mandel, MD, University of Pennsylvania, Philadelphia, Pennsylvania, and colleagues evaluated their anaesthetic technique in 97 patients participating in a study of robot-assisted surgery for severe sleep apnoea.
Visualizing the site of the obstruction in the upper airway is an important part of planning for apnoea surgery. This can be done using drug-induced sleep endoscopy (DISE), in which stepwise doses of anaesthetic doses are given to put the patient to sleep and reproduce the airway obstruction causing apnoea. However, it’s challenging to achieve just the right anaesthetic dosage. The standard technique for DISE is time-consuming and not well-suited for widespread clinical use.
In the new ramp control approach, a computerised algorithm is used to calculate the 2-dose sequence of anaesthetic administration likely to produce sedation in each individual patient. By contrast, the standard stepwise approach to DISE uses a sequence of up to 9 doses.
The 97 patients studied had severe sleep apnoea, with a median of 48 apnoea-hypopnoea events per hour on standard testing in the sleep laboratory. The patients were being evaluated for surgery after receiving no benefit from continuous positive airway pressure (CPAP).
The ramp-control DISE approach allowed doctors to see and photograph the obstructive anatomy in all 97 patients. The median time to put the patient to sleep and demonstrate the cause of obstruction was just under 4 minutes.
Just as important, the necessary level of sedation was achieved without an undue drop in oxygen saturation levels. The median lowest oxygen saturation level during DISE was about 91% compared with an 81% value recorded in standard sleep studies.
With DISE, it is easy to “overshoot” the anaesthetic dose, which may lead to drops in oxygen saturation, requiring airway support steps to maintain the patient’s blood oxygen level. The ramp-control DISE technique is efficient, administering just enough anaesthetic to produce the desired level of sedation within a few minutes; and safe, with relatively small drops in blood oxygen saturation level.
“The effective sedation seen in this study with a low rate of desaturation and infrequent need for airway support is an important result,” the authors wrote.
They added that more research will be needed to determine how well the new technique can be generalised to everyday clinical practice at busy surgical centres.