Efficacy of Positive
Airways Pressure and Oral Appliance in
Mild to Moderate Obstructive Sleep Apnea.
Maree Barnes, R.
Douglas McEvoy, Siobhan Banks, Natalie Tarquinio,
Christopher G Murray, Norman Vowles, and Robert J Pierce
Am. J. Respir. Crit. Care Med. published 16 June 2004, online.
The efficacy of currently – recommended treatments is uncertain in
patients with mild to moderate obstructive sleep apnea (apnea –
hypopnea index 5-30). A group of 114 sleep clinic patients with
apnea- hypopnea index 5-30 have participated in a randomized
controlled crossover trial of 3 months treatment with each of nasal
continuous positive airways pressure, a mandibular advancement
splint and a placebo tablet. Outcomes were sleep fragmentation and
hypoxemia, daytime sleepiness, quality of life, neurobehavioral
function and blood pressure.
Both active treatments improved sleep outcomes, but positive
pressure had a greater effect.
Quality of life, symptoms and subjective but not objective
sleepiness improved to a similar degree with both treatments,
however many of the improvements seen in the neuropsychological
function and mood were no better then the placebo effect.
Some aspects of nocturnal blood pressure were improved with the
splint but not with continuous positive airway pressure.
This study has shown that although both continuous positive airways
pressure and mandibular advancement splint effectively treated
sleep-disorder breathing and sleepiness, the expected response in
neurobehavioral function was incomplete. This may be due to the
splint having a lesser therapeutic effect, and the continuous
positive airways pressure being poorly tolerated and therefore used
less in this patient group.
used; CPAP Resmed Australia. Oral Appliance MDSA® supplied by RJ
& VK Bird Pty Ltd)
What the paper specifically states about the
…patients were excluded if they did not have at least 2 teeth in
the upper and lower jaws on both left and right sides to enable
adequate retention of the MDSA®
…only 5 patients out of 99 could not be fitted with an MDSA®
…The goal of the MDSA® advancement was maximum comfortable
At the initial fitting, the MDSA®was advanced maximally as
tolerated by the subject. Subjects were reviewed weekly and the
MDSA® advanced further. (wash in period for the MDSA® was 1-3
weeks). When no further advancement was possible, the screw was,
sealed, advancement measured, and 3 month treatment period
.. no subjects required an extra dental visit.
…Mandibular advancement with the MDSA® was 10..3 ± 0.3mm. And
ranged between 1-13mm. Seventy five percent of subjects required at
least 75% of maximum possible protrusion.
…only one subject was unable to tolerate CPAP and two were
unable to use the MDSA®
the MDSA® design:
...There has been concern that vertical
dimension opening of an oral appliance may result in posterior
movement of the tongue and soft palate with consequent reduction of
the posterior airway space and worsening of sleep disordered
breathing. The AHI increase in uncontrolled oral appliance trials
has attributed to a problem with the design of the oral
...however we found that
significantly fewer subjects had an AHI increase with MDSA® than
CPAP - MDSA®
Nights per week: 4.2 ± 0.3 5.3 ± 0.3
Hours per night: 3.6 ± 0.3 5.5 ± 0.3
…It has been proposed that effective CPAP treatment of OSA requires
usage for at least 4hours per night on at least 70% nights. 43% of
subjects treated with CPAP received adequate treatment, 71% with
….. suggesting that the CPAP response extends to low usage
...In addition to the primary analysis, we measured the improvement
in sleep disordered breathing with the MDSA® using response
definitions that have been used in similar studies. A complete
response is defined as a reduction in the AHI to below 10, and
partial response is a fall of at least 50% in the AHI but not below
10, with an improvement in symptoms; the remainder of subjects are
classified as treatment failures. By this criteria 49.1% subjects
had a complete response to the MDSA®, and a further 6.1% had a
(55.2% in total)
...Both treatments (CPAP-MDSA®) were more effective than placebo in
improving quality of life symptoms and subjective not objective
sleepiness, with neither treatment being better than the
...There was no response in blood pressure to CPAP, however
MDSA® improved the nocturnal diastolic blood pressure and
significantly increased the proportion of subjects with a normal
night time dip in blood pressure.
...The blood pressure response to MDSA® was greater than that to
CPAP, and raises the possibility that some aspects of CPAP
treatment may mitigate against a lowering of blood pressure in the
mild OSA severity range. To our knowledge, there have been no other
published controlled trials of the effect on blood pressure of
treating OSA subjects with CPAP,and none with an oral