Applying this information and adjusting for pairwise comparisons, 10 complete data sets provided a statistical power of 95% (a=0.05) to detect a 2-cm H20 difference in CPAP requirement between T0 and T2/T4. Similarly, because the data spread among the patient and control groups for the other outcome variables were narrow, the study afforded satisfactory statistical power to detect clinically important change in these variables. Read the rest of this entry »
Available literature shows a loose correlation only between subjective and objective measures of sleepiness and alertness such that it is not surprising to find a change in subjective sleepiness without any corresponding objective change. The current study showed some internal consistency in that the ESS scores and the MWT latencies were both in the normal range at 2 and 4 weeks after commencement of CPAP treatment in the retitrated patients, confirming a satisfactory treatment response that was well maintained after reduction of the CPAP. Thus, our findings could be construed as a gradual acclimatization to using CPAP over the first few weeks of treatment, possibly facilitated by eliminating superfluous pressure during part 1 of the current study. Read the rest of this entry »
This is a better outcome from CPAP treatment than others have reported in patients with less severe OSA. Furthermore, whereas even a single night without adequate CPAP treatment results in significant daytime sequelae from OSA, the adjustment to lower CPAP after 2 weeks in the present protocol was not associated with any subjective or objective deterioration.
Patients (parts 1 and 2) in this study complied satisfactorily with CPAP (average use >6 h) both before and after reducing the CPAP. It has been suggested that patients with severe OSA may be more motivated to use CPAP because of greater disease-related sequelae. As mentioned earlier, most patients who decline CPAP treatment for OSA do so early. Subjective sleepiness tended to decrease in the second 2-week period as compared with the first, in both parts of the study, but this reduction in subjective sleepiness was statistically significant only in part one of the study. Read the rest of this entry »
Our decision to perform CPAP titrations by an experienced technician, rather than to use the autosetting CPAP device, was based on several arguments: (1) lack of validation studies against standard manual CPAP determination in OSA; (2) lack of long-term outcome studies of patients with OSA titrated using automatic CPAP titration; (3) philosophical differences—our concern in treating patients with OSA is to optimize sleep quality—not necessarily to eliminate minor obstructions such as snoring without arousals. We attempted to minimize any operator bias by (1) performing the study in single-blind fashion such that the technician performing the titrations was not informed of the optimal pressure determination by the clinical polysomnographer, and (2) recoding all studies into random numbers and using the opinion of the blinded clinical polysomnographer as to the optimal CPAP pressure in a given body position and sleep stage. Read the rest of this entry »
Others have also demonstrated changes in CPAP requirement over more prolonged follow-up studies of OSA. Series and colleagues demonstrated that the required CPAP progressively decreased (from 9.6 to 7.7 cm H20) during the first 8 months of treatment in patients with OSA. Similarly, Boecker and colleagues found a reduction in the effective CPAP in 57% of 30 OSA patients, over a follow-up period of 6 to 15 months. The authors of these two studies, however, did not standardize the CPAP requirement for sleep stage and position, and did not assess the effect of the alteration in CPAP requirement on other outcome measures. It is also important to control for changes in weight, ventilatory control, and nasal obstruction over longer follow-up periods, as these factors may also contribute to a change in CPAP requirements. Read the rest of this entry »
Our results demonstrate a fall in CPAP requirement of approximately 2 cm H20 within 2 weeks of starting CPAP treatment in patients with severe OSA. Why should this be? One plausible explanation for this finding, which has gleaned considerable support from recent studies, is that the upper airway in patients with OSA undergoes anatomic change resulting in an improved upper airway caliber soon after commencing CPAP treatment. In 24 male patients with OSA who underwent erect and supine cephalometry before and after treatment with CPAP for at least 3 months, Mortimore et al demonstrated a widening of the posterior airway space while awake in the supine position after CPAP treatment. Read the rest of this entry »
Anxiety scores were lower during the T2 to T4 period (median, 3; range, 0 to 4) as compared with T0 to T2 (median, 4.5; range, 1 to 6; median difference, 2; 95% Cl, 0.5 to —2.9; p=0.03), as shown in Figure 5. Depression scores were similar between the two periods of CPAP treatment (T0 to T2 median, 2; range, 1 to 8; T2 to T4, 2.5; range, 0 to 7; median difference, 1; 95% Cl, —0.9 to 1.7, p=not significant [NS] (Fig 5).
ESS scores tended to decrease in the control group during T2 to T4 (mean, 6.3 [1.4]) as compared with T0 to T2 (8.3 [1.3]), but this difference was not statistically significant (mean difference, 2.1; 95% Cl, 0.3 to 4, p=0.17). Read the rest of this entry »