The polygraphic sleep recordings comprised EEG, EMG, EOG, nasal and oral thermistors and thoracic and abdominal strain gauges. Scoring of sleep stage was done according to the criteria of Rechtschaffen and Kales. The sleep recordings were coded and analyzed blindly after the completion of the study of each patient. The Sa02 was monitored with a Biox III ear oximeter and transcu-taneous Pco2 with a Hewlett Packard 47210A cutaneous capnometer. These two variables were recorded separately, coded and analyzed as previously described after the completion of the study of each patient. The drug code was not broken until the whole study was finished.
The following variables were analyzed: mean Sa02 during nocturnal wakefulness and during each sleep stage, lowest SaOa during sleep, and tcPco* at its highest and lowest value during the night; sleep latency from “lights out,” total sleeping time, sleep efficiency index and number of awakenings during the sleep period; fraction of total sleeping time spent in the various sleep stages and number of sleep stage transitions; number and duration of sleep apneas (if any).
The main statistical evaluation was a between-nights comparison of Sa02 at each sleep stage and during all sleep, sleep induced change in tcPco2 and number and duration of sleep apneas using a two-way analysis of variance. A secondary evaluation was a comparison of total sleeping time, sleep latency and sleep quality between the three study nights. This was, however, not the main purpose of the study.
Written informed consent was obtained from each participant and the study was approved by the medical ethics committee at the University of Lund. http://birthcontroltab.com/
Entry data from the 14 patients in the final analysis (eight male and six female subjects) are presented in Table 1. During the treatment nights, shorter sleep latencies, longer total sleeping times, higher sleep efficiency indices and fewer periods of wakefulness were observed (Table 2). However, there were no differences with respect to the percentage of total sleeping time spent in each sleep stage (Fig 1).
Table 1— Entry Data, Means and SD
|Age||Weight, % Predicted||VC, % Predicted||FEV,, % Predicted||Pa02, kPa||PaC02, kPa||Sa02, %|
|65±6.1||97 ±15||60± 15||31 ±11||8.4 ±0.63||5.8 ±0.74||90.5 ±2.8|
Table 2—Sleep Variables (Means and SD)
|Sleep Latency (min)||Total Sleeping Time (min)||Sleep Efficiency Index(%)||Periods of Wakefulness||Sleep Stage Transitions|
|Placebo||3+i3||289 ±82||68± 19||20± 11||96 ±32|
|Nitrazepam||12 ±11||350 ±71||84± 12||13 ± 7||88± 18|
|Flunitrazepam||8±7||358 ±66||83± 15||15 ±6||82 ±26|
Figure 1. Distribution of sleep stages for placebo and treatment nights. The horizontal lines represent the normal values from our laboratory.