Study objectives: To evaluate the effects
of humidification on nasal symptoms and compliance in sleep apnea
patients using continuous positive airway pressure (CPAP).
Design: A randomized, crossover design was employed.
Setting: The study was conducted at two suburban
community-based hospital sleep laboratories.
Data were collected on 38 obstructive sleep apnea patients (mean age,
44.1 years) in whom CPAP was a novel treatment.
Interventions: The interventions were heated humidity, cold
passover humidity, and a washout period without humidity.
Measurements and results: Patients were titrated with
heated humidity or cold passover humidity in the laboratory and
subsequently initiated on humidity. Objective compliance, self-report
of factors affecting CPAP use, satisfaction with CPAP, feeling upon
awakening, and daytime sleepiness were assessed at the completion of
each 3-week treatment period and a 2-week washout period. Outcome
measures were assessed with one-way analysis of variance followed by
Scheffe post hoc comparisons. Significant main effects
were observed for compliance (F2,37 = 5.2; p = 0.008),
satisfaction with CPAP (F2,37 = 4.5; p = 0.01), and
feeling refreshed on awakening (F2,37 = 4.4; p = 0.02).
A significant decrease in daytime sleepiness was observed between
baseline and each of the conditions (F3,37 = 55.5;
p < 0.0001), but Epworth sleepiness scale scores did not differ
between conditions (all p values > 0.56). CPAP use with heated
humidity (5.52 ± 2.1 h/night) was greater than CPAP use without
humidity (4.93 ± 2.2 h/night; p = 0.008). Compliance differences
were not observed between CPAP use with cold passover humidity and CPAP
use without humidity. Patients were more satisfied with CPAP when it
was used with heated or cold passover humidity (p ≤ 0.05). However,
only heated humidity resulted in feeling more refreshed on awakening
(p < 0.05). No significant differences were observed among the three
groups on the global adverse side effect score
(F2,37 = 2.5; p = 0.09). Specific side effects such as
dry mouth or throat and dry nose were reported less frequently when
CPAP was used with heated humidity compared to CPAP use without
humidity (p < 0.001).
Conclusions: Compliance with
CPAP is enhanced when heated humidification is employed. This is likely
due to a reduction in side effects associated with upper airway
symptoms and a more refreshed feeling upon awakening. Compliance
gains may be realized sooner if patients are started with heated
humidity at CPAP initiation.