Those with a high number of mixed apneas will have a greater likelihood of central apnea with PAP. To my knowledge what is not predictable is whether the residual central apnea will resolve after a couple of weeks of fixed/auto pressure.

Dear Imran Khawaja,

Clearly if patients have pre-existing central apnoeas, then CPAP by eliminating the obstructive apnoeas will leave the central apnoeas behind. There are also some theoretical reasons why if patients are near their apnoea threshold already then CPAP, by altering the mode of breathing and improving alveolar ventilation may potentially cause them to drop their carbon dioxide tension below the threshold and induce central apnoeas. We studied this concept to elucidate the human apnoea threshold using non invasive ventilation.

Hope this helps.

Datta et al (1991) THE INFLUENCE OF INDUCED HYPOCAPNIA AND SLEEP ON THE

ENDOGENOUS RESPIRATORY RHYTHM IN HUMANS. Journal of Physiology, 440, pp. 17-33

The only parameter that can help to predict CompSAS is the presence of a more fragmented sleep pattern at baseline.

My experience is limited to stroke cases.

In our series we have observed that:

1. All stroke cases affected by a sleep disordered breathing (SDB) have a mixed sleep apnea (SA) (none of them presented a pure OSA or pure CSA)(1)

2. Comparing clinical/instrumental data of stroke cases affected by OSA to those affected by CSA, we found no differences among the two groups (including BMI mean values , BMI>30, and increase in pharyngeal tissue or obstruction of upper airways at ORL evaluation)(2)

3. Patients affected by CSA referred symptoms other than daily sleepiness more frequently than stroke cases without OSA; not the same for stroke-OSA cases (3)

4. Cases with CSA were more frequently than OSAs affected by conditions predisposing to obstruction of upper airways during sleep, although not reaching the statistical significance (i.e.BMI>30, increase in pharyngeal tissue or obstruction of upper airways at ORL evaluation)

5. No correlation were found between the site of brain lesion and the type of SDB disturb

Those observations have led us to postulate the hypothesis that the subgroup of stroke cases that will develop a complex sleep apnea are those with an altered loop gain (4)

Obviously this must be tested.

References

1. Sacchetti M, Di Mascio M, Della Marca G, et al. Sleep Disordered Breathings in Patients with Stabilised Stroke – A Case Control Study. European Neurological Review 2013;8:6.

2.Sacchetti ML, Di Mascio MT, Fiorelli M, et al. MRI and polysomnographic findings of patients affected by post-stroke sleep apnea. Health 2013;5:49.

3.Sacchetti M, Di Mascio M, Marca G, Minni A, Ottaviani S. Sleep Disordered Breathing after Stroke: Clinical Profile of Patients with Obstructive-as Opposed to Central-Sleep Apnea. J Sleep Disorders Ther 2013;2:2167-0277.1000.

4. Sacchetti ML, Di Mascio MT, Ottaviani S, et al. May stroke cause a Complex Sleep Apnea-CompSA? Sleep Med 2012.

Article Sleep Disordered Breathings in Patients with Stabilised Stro...

Patients with instable heart disease and patients with irregular leaks are more likely to develop compSA. There is however no evidence based medicine.

Central and mixed events present at the initial diagnosis could disappear if their are consecutive to heart instability related to obstructive event and associated hypoxemia.