Side effects from CPAP therapy tend to be minor though can often be a significant barrier between long-term adherence (113) and tend to be related either due to problems with the interface or due to positive pressure. Common complaints include nasal congestion, rhinorrhea, skin abrasion, difficulty with exhalation, chest discomfort, dry mouth, claustrophobia, conjunctivitis due to air leak, and/or aerophagia (114). Reports document up to 10% of all CPAP users complaining of some degree of persistent nasal congestion at six months after initiation of CPAP therapy (115). This finding is likely related to reduced humidification of the inspired air causing release of inflammatory mediators (116). Extremely rare are reports of serious complications including pulmonary barotrauma, pneumocephalus (subsequent to base of skull fracture), tympanic membrane rupture, massive epistaxis, subcutaneous emphysema, decreased cardiac output at high pressure, and increased intraocular pressure, which have been reported in association with the use of nasal CPAP (114,117-119). Most side effects or problems can be resolved (Table 1) with careful attention to interface options with appropriate selection of mask type and fit, careful and methodological assessment of patient symptoms, and careful monitoring of patients at risk for serious complications, such as those with bullous lung disease.
Although CPAP is the definitive treatment for sleep-related breathing disorders, there are still limitations to this therapy. The most obvious limitation is the ability of certain individuals to tolerate PAP. As will be discussed later in this chapter, adherence to CPAP therapy is the greatest obstacle for the clinician to contend with, and this is largely dictated by the patient's ability to tolerate CPAP. Additionally, certain patients require such high pressures to definitively treat their disease that mask leak is largely unavoidable, making tolerance all the more difficult to achieve. Patients with severe nasal obstruction often will not tolerate a traditional nasal mask interface and require a full-face mask, which anecdotally is less tolerated than a nasal mask. Alternatively, nasal surgery may allow for better tolerance of PAP therapy through decreased nasal resistance (120). Other issues that arise which may in turn limit an individual's adherence with therapy include lifestyle inconvenience, such as that encountered when trying to travel with a CPAP device. Fortunately, airport
TABLE 1 Common CPAP Problems and Solutions
Air leakage through mouth Condensation of water in CPAP hose Claustrophobia
Dry mouth and/or nose Eye irritation
Inadvertently removing mask during sleep
Mask discomfort Mask leak Nasal congestion
Skin breakdown from mask at bridge of nose
Reduce CPAP pressure; consider BPAP or APAP Add chinstrap or switch to full-face mask Add insulated sleeve around hose Switch to different mask or try nasal interface; desensitization (i.e., wearing device for progressively longer periods) Add humidification and apply saline drops in nose;
add chinstrap or switch to full-face mask Refit or adjust mask; apply saline drops in eyes;
add eye mask Adjust alarm setting on machine; apply surgical tape at edge of mask and skin, since removal of tape may awaken patient and prevent removal of mask; consider PAP re-titration Switch to different mask Refit or adjust mask
Add heated humidification; add nasal saline, decongestant, antihistamine, and/or nasal steroid; switch to full-face mask; correct possible anatomic defect in nose or sinuses Place device under bed or away from patient (may need extension hose), but avoid covering air intake port to device; switch to another device Consider PAP re-titration; instruct patient on ramp feature of device; switch to APAP, BPAP, or flexible PAP Refit mask or switch to different mask; try nasal interface
Abbreviations: APAP, automatic positive airway pressure; BPAP, bilevel positive airway pressure; CPAP, continuous positive airway pressure; PAP, positive airway pressure. Source: Courtesy of C. Kushida.
security personnel have become increasingly informed about CPAP and usually make allowances for individuals traveling with these devices.
Another potential limitation of CPAP therapy is its application in the pediatric patient population. While tonsillectomy and adenoidectomy is the mainstay of treatment for pediatric OSA, a small but significant portion of pediatric patients with OSA will have persistent sleep-disordered breathing postoperatively, indicating a craniofacial etiology for their disease (121,122). CPAP is thus indicated for treatment until such time that surgical intervention can be performed to correct the skeletal abnormality predicating the disease. Surprisingly, CPAP is relatively well-tolerated in a large percentage of these patients, with studies indicating up to 80% adherence (123,124); however, attaining adherence in pediatric patients intolerant of CPAP is fairly difficult.
Interestingly, while adherence with PAP therapy is clearly an issue, the question of how much nightly usage constitutes "adherence" is not well understood and often debated. An interesting notion that has likely fueled this debate is one that suggests that there exists a residual benefit from CPAP when used only a few hours a night, which seems to reinforce this idea of 4.5 hours/night of use to be adequate. A study by Hers et al. (125) found that in 24 patients with newly-diagnosed OSA, after being titrated to normalization of their sleep and breathing during the first half of the night, a partial improvement of OSA severity and mean oxygen severity occurred during the second half of the night without treatment. Sleep architecture was notably more fragmented during the second half of the study night without therapy. It is possible that this carryover effect is what is responsible for subjective benefits reported by patients who are only partially compliant with treatment. The topic of adherence is discussed in more detail later in this chapter.
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