5.1 Introduction

Many different surgical approaches have been used in the treatment of OSAHS, all with the intention of increasing pharyngeal calibre and reducing pharyngeal resistance during sleep.

5.1.1 METHODOLOGICAL DIFFICULTIES

There are no RCTs comparing surgical treatments for OSAHS. Unfortunately, because of large placebo and regression to the mean effects in OSAHS, uncontrolled trials are rarely convincing. Regression to the mean occurs when there is fluctuation in the objective and subjective severity of a condition with time. On the whole, patients will present, and be more likely to be selected for treatment, when they are at their worst. Therefore, on average, they will be better the next time they are studied, regardless of any intervention. Attempts to control for this can be made by having two or three pre-intervention studies, but even this is not as good as randomised, placebo-controlled trials.

An alternative experimental design, which may partially control for regression to the mean, is to show different response rates to surgery depending on some preoperatively determined criteria. For example, the result of a preoperative anatomical assessment of patients with OSAHS could be used to subdivide a group of patients, who are otherwise similar. If the surgical outcome was significantly better in one group compared to the other, then this latter group is a form of control. Such studies have produced differing results, but unfortunately such preoperative subdivisions tend to produce groups unmatched for some other measures, such as OSAHS severity or body weight.

5.2 Uvulopalatopharyngoplasty (UPPP)

5.2.1 EFFECTIVENESS

There have been two systematic reviews that concluded there was no RCT evidence supporting the use of UPPP in OSAHS. Uncontrolled case series suggest, at best, a 50% improvement in 50% of patients.^{131, 132} The effects on objective measures of OSAHS were poor and largely unpredictable, although statistically significant overall. A meta-analysis of laser-assisted uvulopalatopharyngoplasty (LAUP) also concluded that LAUP and related procedures should not be used for any severity of OSAHS.¹³³ Evidence level 2++

Use of UPPP or LAUP for the treatment of OSAHS is not recommended.

Tonsillectomy is usually carried out in conjunction with conventional UPPP, but may in its own right improve OSAHS. Case series support this conclusion but no RCT data exist.^{134, 135} Evidence level 3

The presence of large tonsils in a patient with diagnosed OSAHS should prompt referral to an ENT surgeon for consideration of tonsillectomy.

Three studies with some potential for controlling for placebo, or regression to the mean, effects were identified.^{136, 137, 138} One study identified 90 patients having UPPP of whom 44 had complete preoperative assessment of pharyngeal collapsibility during an awake Mueller manoeuvre (generation of subatmospheric intra-pharyngeal pressure) and 31 patients were monitored postoperatively.¹³⁶ The postoperative improvement in AHI was better in the group with collapse limited to the palatal area, compared to those with more extensive collapse. The division of the patients in this way produced groups with differing OSAHS severity and, by chance, a very different time to the follow up assessment. It is impossible to confidently ascribe benefits to the surgery itself. Evidence level 2+

Another study compared patients randomly assigned to receive UPPP or conservative management, which should have removed regression to the mean, but not placebo, effects.¹³⁷ There was no significant difference in the main objective measures of OSAHS severity, although there was improvement in the subjective assessment of symptoms. Sub-analysis of oximetry indices of severity showed more improvement in the surgically treated group (number with a normal SpO2 dip rate at one year, 14% versus 45%). Three of 14 patients in the control group were operated on despite their randomisation to conservative management.

The third study randomised 95 patients with symptomatic OSAHS to either IODs or UPPP.¹³⁸ The follow up analysis was not on an intention to treat basis and the dental result may be biased in favour of a bigger effect. Overall dental devices were more effective than UPPP. The effect sizes at 12 months were small for both dental and UPPP treatments, (0.14 and 0.1 respectively based on oxygen desaturation index, and 0.33 compared with 0.24 based on AHI).

5.2.2 SIDE EFFECTS

Two studies have described, and estimated the immediate and long term prevalence of, the morbidity and mortality following UPPP.^{139, 140} This issue is of interest to anaesthetists as deaths have been reported in the perioperative period. The deaths have been assumed to be due to worsening of upper airway obstruction and depression of ventilatory drive. One study reported that most problems occur in patients with comorbidity, such as a BMI > 35.¹⁴¹ It appears prudent to provide nasal CPAP postoperatively, or even a temporary tracheostomy. Severe postoperative pain occurs and changes in voice and nasal regurgitation of food following UPPP are also possible.¹⁴²

5.2.3 SNORING

UPPP and related procedures are also used extensively in the treatment of snoring.^{143, 144, 145, 146} Significant OSAHS is present in over 30% of snorers presenting to a specialist clinic, even when not overtly sleepy.¹⁴⁶ In order not to inadvertently operate on patients with OSAHS, sleep study assessment to exclude this diagnosis is an advisable part of any preoperative evaluation. UPPP is associated with the standard risks of surgical morbidity and is not an effective treatment for OSAHS. In addition, UPPP has an adverse effect on the patient’s subsequent ability to use nasal CPAP.¹⁴⁴ Evidence level 3

OSAHS should be excluded in patients before they are considered for surgery for snoring.

Patients being offered palatal surgery should be informed of the risk of difficulty with CPAP use if they later develop OSAHS.

5.3 Tracheostomy

Tracheostomy was the first surgical treatment for OSAHS and bypasses the obstruction completely. There have been no controlled trials to assess longer term outcomes, particularly self-assessed health benefits, which are important given the potential complications of a tracheostomy.

Tracheostomy should only be considered when all else fails in carefully selected individuals.

5.4 Other surgical techniques

5.4.1 MANDIBULAR ADVANCEMENT

One controlled trial has shown that permanent mandibular and maxillary advancement considerably reduces OSAHS severity and improves symptoms in patients followed up for two years.¹⁴⁷ There are no RCTs and only limited long term follow up data available, and the treatment remains experimental.

5.4.2 SUPRAHYOID TENSING

A randomised study of a surgical procedure to tense the suprahyoid muscles (hyoid suspension) was halted due to worsening of sleep study indices, despite apparent symptomatic improvement.¹⁴⁸

5.4.3 BARIATRIC (WEIGHT REDUCING) SURGERY

Weight is known to influence the severity of OSAHS and weight loss is likely to be an effective treatment for OSAHS in some patients. Bariatric surgery to provoke significant weight loss has been used to treat OSAHS, assessed in case series.¹⁴⁹ In the absence of a controlled trial, the relative benefits and disadvantages cannot be assessed. This area urgently needs evaluation.

5.4.4 NASAL SURGERY

Nasal surgery may play a role in improving compliance with nasal CPAP by reducing nasal resistance and allowing a reduction in the pressure required.^{150, 151} There is no evidence that it produces an improvement in OSAHS symptoms. Evidence level 2+,4

Alternative surgical approaches to OSAHS are experimental and should not be used outside the context of an RCT.

5.5 Anaesthesia

Obstructive sleep apnoea presents specific problems for the anaesthetist and regional anaesthetic techniques should be used where possible. Even following minor surgery, the patient suffering from severe OSAHS is likely to require care in a high dependency or intensive care unit (HDU or ICU) postoperatively. Premedication sedative drugs are not advised and postoperative opiate analgesia should be titrated carefully to avoid increasing the frequency of apnoeic episodes and precipitating oxygen desaturation. Obesity adds to the anaesthetic risk as do other associated conditions such as hypertension and cor pulmonale.¹⁵² Evidence level 4

There is an increase in intubation difficulty even in mild to moderate OSAHS and anaesthetists should be aware of this possibility in all OSAHS patients.¹⁵³

The effect of anaesthesia during surgery may increase the severity of the apnoea postoperatively. When a patient is being treated by CPAP preoperatively this should be continued immediately following surgery.

All patients with OSAHS should be monitored with oximetry postoperatively and further management decided on an individual basis.