RT for Decision Makers in Respiratory Care - June 2007
Sleeping Safely
Improving Compliance with CPAP
by John D. Zoidis, MD
Strategies to improve CPAP compliance include patient and provider education,
maximization of patient comfort with the CPAP device, and regular follow-up.
Continuous positive airway pressure (CPAP) is the preferred treatment for
obstructive sleep apnea syndrome (OSAS). It allows progressive restoration of
airflow, as the pressure applied exceeds the airway opening pressure. Appropriate
CPAP can resolve OSAS in many patients.1,2 In addition to improving sleep quality
in patients with OSAS,3,4 CPAP has been shown to decrease daytime sleepiness and
lower blood pressure.5,6 Standard CPAP administered at a sleep center requires
pressure titration. Home CPAP utilizing auto-adjusted titration has become more
prevalent as the number of available devices has increased and the clinical evidence
demonstrating their efficacy has grown, although the degree of growth has been
constrained by reimbursement issues.
Despite the positive aspects of CPAP, compliance can be difficult to achieve. CPAP
can cause nasal congestion, claustrophobic sensations, and other side effects.
Adequate compliance is being recognized increasingly as a major determinant of
treatment success, and various strategies have been employed to enhance
compliance with CPAP.
Prevalence of OSAS
Studies in the United States, Europe, and Australia have shown that a substantial
proportion of the adult population has mild-to-moderate OSAS.7,8,9 According to
the American Lung Association, as many as 18 million Americans suffer from
OSAS.10 Men are more susceptible than women, and sleep apnea clusters have been
observed within families.10 Obesity appears to be a predisposing factor.11
Why Treat OSAS?
Apnea and hypopnea cause temporary elevations in blood pressure in association
with blood-oxygen desaturation, arousal, and sympathetic activation, and can cause
elevated blood pressure during the daytime and, ultimately, sustained hypertension,
putting individuals with sleep apnea at risk for hypertension and, possibly, heart
disease.12
OSAS is associated with neurohormonal and electrophysiological abnormalities that
may increase the risk of sudden death from cardiac causes, especially during
sleeping hours. This was demonstrated in a postmortem review of polysomnograms
and death certificates of 112 patients who had undergone polysomnography and
had died suddenly from cardiac causes.13 At four intervals of the day, the
investigators of this study compared the rates of sudden death from cardiac causes
among patients with OSAS and rates among people without OSAS; rates in the
general population; and expected rates according to chance alone. From midnight to
6:00 am, sudden death from cardiac causes occurred in 46% of people with OSAS,
compared with 21% of people without OSAS (P = 0.01); 16% of the general
population (P < 0.001); and 25% expected by chance alone (P < 0.001). As the
investigators noted, the findings from this study demonstrate that people with OSAS
have an increased risk of sudden cardiac death during sleeping hours. This contrasts
strikingly with the low incidence of sudden cardiac death during sleeping hours in
people without OSAS and in the general population.
Individuals who experience severe OSAS can lose so much sleep that their level of
alertness during wakefulness is seriously impaired. Such a lack of alertness can pose
a serious hazard if they are operating heavy machinery or driving a car. In fact,
numerous investigators have found a strong correlation between sleep apnea and
the risk of traffic accidents.14,15,16,17
Laboratory-Based CPAP Versus Home CPAP
Home CPAP is a relatively recent technology by which a CPAP device automatically
adjusts the level of mask pressure to the patient’s requirements. The rationale for
home CPAP is to improve treatment efficacy, enhance compliance with treatment,
and perform automatic titration. Auto-titration makes sense because patients’
pressure requirements vary over both the short and long term.18 The rationale
behind improved compliance with treatment is that home auto-adjusted CPAP
should achieve the same treatment efficacy with lower nasal pressures, thereby
reducing adverse effects and improving compliance.18 The evidence base
supporting the use of home CPAP is growing.
Meurice and colleagues19 performed a randomized study to compare the efficacy of
an auto-titration CPAP (aCPAP) device (Morphee Plus®, Mallinckrodt, St Louis) with
that of conventional CPAP in 16 patients with OSAS. Sleep improvements were
similar in both groups, and the apnea/hypopnea index (AHI) was within the normal
range at study end in both groups.
Huskins20 performed a randomized, single-blind, crossover trial to compare
compliance and treatment response between standard CPAP and aCPAP. Patients
with OSAS who required CPAP treatment underwent 2 months each of CPAP and
aCPAP in random order at a sleep center. Outcome assessments included Epworth
Sleepiness Scale (ESS) Score, Short Form–36 (SF-36) Health Survey, visual analog
scale to measure ease of and attitude to treatment, side effects, and treatment
pressures or system leaks obtained from an Autoset T® device (ResMed, Poway,
Calif). There were no differences between treatment modalities in overall
compliance, ESS scores, or SF-36 scores. There were fewer reported side effects in
aCPAP mode, and compliance was greater with aCPAP in patients reporting any side
effects. Auto-titrated CPAP delivered significantly lower airway pressures and
resulted in fewer system leaks. In this study, compliance, subjective sleepiness, and
quality of life were similar between patients who used standard CPAP and those
who used aCPAP.
Senn and colleagues21 evaluated the efficacy of two different CPAP devices with
automatic mask pressure adjustment in comparison with fixed CPAP in 29 patients
with OSAS. Patients were treated over three consecutive 1-month periods with
three regimens in random order: an aCPAP device responding to apnea-hypopnea
and snoring, another aCPAP device responding to snoring and changes in flow
contour, and fixed CPAP at the 90th pressure percentile titrated by aCPAP over 2
weeks. At the end of each treatment period, symptoms, quality of life, and nocturnal
breathing disturbances were evaluated. All three treatment modalities improved
symptoms, quality-of-life domains, and AHI significantly and to a similar degree. The
investigators concluded that both aCPAP devices were as effective as fixed-pressure
CPAP in improving outcomes in patients with OSAS.
More recently, Nussbaumer and colleagues22 performed a randomized, controlled,
double-blind, crossover trial comparing the efficacy of a novel aCPAP machine
(REMStarAuto®, Respironics, Murrysville, Pa) operated in auto-adjusted or
constant mode in 30 patients with OSAS. Patients were randomly assigned to 1
month of home therapy with aCPAP followed by 1 month with CPAP, or vice versa.
After 1 month with either treatment, mean ESS score, sleep resistance time, and
mean AHI were significantly improved; 26 patients preferred aCPAP, and four
patients preferred CPAP. Although these results are encouraging, the overall efficacy
of auto-titrated CPAP in increasing the hours of use remains unclear.
Home CPAP is not without potential disadvantages. Ineffective adjustment of
pressure can result from mouth or mask leaks, rapid alteration between sleep and
wake periods, or occurrence of central hypopneas.23 In addition, prolonged periods
of high pressure may aggravate both leaks and sleep instability.
Strategies to Increase Compliance with CPAP
Most CPAP devices now contain circuitry that records hours of usage and the
pressure at any given time. There are also software tools that can be used to help
the respiratory therapist monitor how patients are using CPAP. However, the most
important strategy for ensuring compliance with CPAP appears to be proper
education of clinicians and adequate follow-up of patients. When these strategies
are followed, CPAP compliance rates of >70% can be achieved, even in the primary
care setting. This was demonstrated in a retrospective trial performed by Ball and
colleagues.24 In this study, sleep-disorder specialists provided a community with
education, diagnostic equipment, and ongoing support as sleep disorders expertise
was established locally. Outcomes for a 2-year period were assessed by chart
review, patient questionnaire, tabulation of polysomnographic data, and
comparison with published reports from specialized centers. Data were collected
from all community physicians on 360 new patients who underwent
polysomnogram testing. The investigators found that with the provision of proper
education, referral for sleep testing increased by almost eightfold. This resulted in
the diagnosis of sleep-related breathing disorders in 81% of patients and periodic
movement disorder in 18%. Nasal CPAP treatment was given to 228 patients, which
represented a greater volume of patients than at many traditional sleep centers, yet
compliance with CPAP was comparable. This study suggests that OSAS is
significantly underrecognized by primary care physicians. The researchers noted
that as a result of the intervention, local sleep expertise was established and large
numbers of OSAS patients were discovered and treated in the community.
Patient education is also important to enhancing compliance with CPAP. In a
randomized trial of 12 subjects, the effect of education on the consequences of OSAS
and the efficacy of CPAP was evaluated.25 One group received two 45-minute
sessions designed to provide education on the consequences of OSAS and the
efficacy of CPAP. The control group received the same extent of therapist contact but
did not receive information on OSAS or CPAP. Compliance data were collected using
CPAP devices with internal microprocessors that were read at 1, 4, and 12 weeks
after treatment initiation. The provision of education enhanced compliance by the
12-week assessment period. Patients who received the education were using CPAP
more regularly at 12 weeks and showed greater improvement on vigilance at
follow-up.
Sin and colleagues studied patients with sleep apnea to determine short-term and
long-term compliance with this treatment, baseline predictors for long-term CPAP
compliance, and whether CPAP use provides sustained improvement in daytime
sleepiness.26 The design was a prospective, longitudinal study of patients referred
to a university sleep disorders center; 296 patients with moderate-to-severe
obstructive sleep apnea, as defined by an AHI of 20 or more events per hour on
polysomnography, were enrolled. Participants were provided with a CPAP device
that contained a computer chip for monitoring compliance. They were informed that
noncompliance would result in the loss of the machine. Within the first week of the
study, patients began making daily telephone contact with a CPAP clinic nurse and
were followed up in the office at 2 weeks, 4 weeks, 3 months, and 6 months. During
each follow-up visit, patients were asked to complete a questionnaire regarding
their degree of daytime sleepiness. Compliance rates (defined as use of the CPAP
machine for 3.5 hours or longer per day) were at or above the 80% mark at each of
the follow-up visits. The daytime sleepiness score improved over the entire followup period, with the lowest score occurring at 6 months. Three variables were found
to correlate with increased use of CPAP—female gender, increased age, and
reduction of daytime sleepiness scores. The investigators concluded that a
population-based CPAP program consisting of consistent follow-up, “troubleshooting,” and regular feedback to both patients and physicians can achieve CPAP
compliance rates of >85% over a 6-month period.
It is important for patients to establish an effective CPAP usage pattern. Several
studies have shown that CPAP usage patterns are developed early in the course of
treatment.27,28 Weaver and colleagues reported that differences in duration and
pattern of CPAP use between compliers and noncompliers could be distinguished by
the fourth night of treatment.28 Other investigators demonstrated that average
nightly use during the first 3 months was highly predictive of long-term CPAP use.29
According to the results of a systematic review,30 the evidence supporting
increased compliance through self-titration and humidification is lacking, but there
is some evidence that psychological and educational interventions might improve
CPAP usage. States Lawrence Epstein, MD, an instructor in medicine at Harvard
Medical School and regional medical director of Sleep HealthCenters®,31 the four
cornerstones of ensuring compliance with CPAP are (1) the maximization of comfort
with the patient-device interface; (2) optimization of the patient’s experience with
CPAP during the early treatment period; (3) appropriate treatment of side effects;
and (4) the provision of long-term support.
Conclusion
Although CPAP is an effective treatment for OSAS, success may be limited by poor
compliance. Optimal compliance is predicated on the provision of adequate
education for both providers and patients; utilization of a CPAP program consisting
of consistent follow-up, “trouble-shooting,” and regular feedback to both patients
and physicians; maximization of comfort with the CPAP device; and treatment of
side effects. Additional factors include the provision of long-term support and the
optimization of the patient’s experience early in the course of CPAP therapy.
John D. Zoidis, MD, is a contributing writer for RT. For further information, contact
RTeditor@ascendmedia.com.
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