No abstract

There is little published literature on the correlation between subjective and objective efficacy of hypnotics. We wanted to determine whether there was a correlation between the patient's subjective evaluation of the efficacy of the hypnotic with the polysomnographic (PSG) findings. We studied 16 patients with chronic insomnia (sleep latency, greater than or equal to 30 minutes; total sleep time, greater than 240 but less than 420 minutes) for 11 nights who took placebos on nights 1 and 2, zolpidem (imidazopyridine) on nights 3-9 and placebo on nights 10 and 11. Patients completed a questionnaire each morning following PSG, which evaluated subjective sleep quality, sleep latency and total sleep time. These data were compared to PSG findings to answer specific questions about sleep latency reduction, efficacy of the hypnotic after a week's use, sleep quality after discontinuing the drug, and any correlation between subjective and objective measures. PSG findings indicated a shortened sleep latency, increased total sleep time, decreased total wake time and increased sleep efficiency when patients ingested zolpidem 30 minutes before bedtime. We found that after 7 nights (nights 3-9) the drug was still effective in reducing sleep latency and increasing total sleep time. Upon withdrawal (nights 10 and 11) sleep returned to baseline (nights 1 and 2). Subjectively, the patients confirmed those findings on the questionnaire, as well as a subjective reduction in the number of awakenings and, interestingly, a subjective increase in the time spent awake after sleep. Many of the objective variables we examined correlated highly with the subjective variables. While on zolpidem, subjects believed and were objectively shown to have a decreased sleep latency, increased total sleep time and decreased time awake before persistent sleep, although they tended to overestimate sleep latency and time spent awake before persistent sleep and underestimated total sleep time. Although the correlation between objective and subjective measures was high for the group, in individual patients there was an impressive difference between the two, and the highest coefficient of variation between a subjective and objective measures was 0.453. No correlations were found with subjective measures of refreshing quality of sleep, decrease in number of awakenings, how sleepy patients felt in the morning or their ability to concentrate in the morning. Thus, we believe the PSG remains the keystone in the evaluation of hypnotic efficacy.

Conventional manually adjusted continuous positive airway pressure (CPAP) is an effective therapy for sleep-disordered breathing. We prospectively investigated the efficacy of a self-titrating nasal CPAP system in the acute treatment of obstructive sleep apnea (OSA) syndrome. Twenty patients with moderately severe OSA [apnea hypopnea index (AHI) > 15/hour] were enrolled in a randomized, controlled, prospective clinical trial. An initial diagnostic sleep study was performed, followed by randomization to a manually adjusted CPAP titration on one night and self titrating CPAP on the other night. On the conventional CPAP night, the CPAP was manually adjusted until abolition of all apneas and electroencephalographic (EEG) arousals, whereas the self-titrating CPAP was set in automatic mode at lights out. The self-titrating CPAP system utilized an algorithm based on airway vibration patterns to detect airway stability. The AHI decreased from 50.8 +/- 28.8/hour [mean +/- standard deviation (SD)] at baseline to 3.8 +/- 3.1/hour (p < 0.005) during manually adjusted and 6.1 +/- 5.3/hour (p < 0.005) during self-titrating CPAP. The arousal index (Ar-I) decreased from 34.1 +/- 23.1/hour (baseline) to 11.2 +/- 5.0/hour on manual adjustment (p < 0.005) and 11.3 +/- 0.3/hour on self titration (p < 0.005), whereas total sleep time was unchanged. No significant differences in any measure of oxygenation or sleep architecture were observed between the manually adjusted and self-titrating CPAP nights except that the lowest arterial oxygen saturation (SaO2) was higher with manual titration (84.4 +/- 4.2% vs. 79.9 +/- 9.7%, p < 0.05). The maximum pressure required for abolition of apneas and arousals was significantly lower (p < 0.05) during the self-titrating study (10.1 +/- 3.8 cmH2O) as compared to manually adjusted CPAP (12.3 +/- 3.9 cmH2O). Failure to increase pressure and failure to maintain minimum pressure occurred in 7 of the 20 subjects during the self-titrating study. This required manual resetting of the system in five subjects, but the system self-corrected in two subjects. An unsupervised study would have resulted in undertreatment of OSA. Based on a single-night laboratory study, self-titrating CPAP was well tolerated and improved OSA and sleep architecture comparable to manually adjusted CPAP. The future modifications of this prototype will require further research to assess its efficacy and safety in the laboratory and home environments before its recommendation for general long-term use.

Many laboratories have large numbers of patients with suspected obstructive sleep apnea (OSA) waiting to be tested. We assessed the use of simple clinical data to detect those patients with an apnea index <20 (low AI) who could be studied less emergently. Using questionnaires completed by patients prior to evaluation, we collected data on 354 consecutive patients (281 males, 73 females; mean age 48.6 years) referred for OSA and assessed with polysomnography (PSG). The questionnaires included the Epworth sleepiness scale (ESS), height, weight, age, and a history of observed apnea. Analysis of receiver operating characteristics curves revealed that both body mass index (BMI) [area under curve = 0.7258, standard error (SE) = 0.03, p < 0.01] and ESS (area under curve = 0.5581, SE = 0.03, p = 0.03) were significantly better than chance alone in detecting people with AI < 20. ESS < or =12 was found in 37.9% of the subjects but 39.6% of those expected to have a low AI using ESS had an AI > or =20. A BMI < or =28 was found in 24.9% of the subjects; 14.8% of those expected to have a low AI using BMI had an AI > or =20. Combining these variables improved accuracy but resulted in smaller groups; a cut-off of ESS < or =12 and BMI < or =28 resulted in a group of 33 (9.3% of subjects), only two (6%) of whom were falsely called low AI. Adding to this the fact that apnea had not been observed resulted in a group of nine patients (2.5% of subjects), none of whom had an AI > or =20. Thus there is a tradeoff; the more variables used, the greater the accuracy but the smaller the percent of cases selected to have low AI. However, in laboratories with hundreds of patients waiting to be tested, any procedure better than chance to help prioritize patients seems worthwhile.