Sleep In Normal Men Research Articles

Average volume-assured pressure support vs conventional bilevel pressure support in pediatric nocturnal hypoventilation: a case series.

Average volume-assured pressure support (AVAPS) is a modality of noninvasive ventilation that provides a targeted tidal volume by automatically adjusting the inspiratory pressure support within a set range. Pediatric studies evaluating the efficacy of AVAPS in treating nocturnal hypoventilation are confined to case reports. The aim of this study was to compare AVAPS to conventional bilevel positive airway pressure (BPAP) support in improving hypercarbia in a cohort of pediatric patients with nocturnal hypoventilation. Retrospective review of patient records at an established tertiary pediatric sleep laboratory over a 6-year period. Ventilatory and sleep study parameters from AVAPS and conventional BPAP titration studies were compared. AVAPS was used only if hypoventilation was not controlled using conventional BPAP. Inspiratory pressures, tidal volumes, and adherence were downloaded on final titrated ventilatory settings. Comparisons were made using paired t test. A total of 19 patients (11 boys, 8 girls; median age 10.5 years, range 1 to 20 years) were identified. Diagnoses included neuromuscular disease (n = 9), obstructive hypoventilation (n = 5), parenchymal lung disease (n = 4), and congenital central hypoventilation syndrome (n = 2). AVAPS demonstrated significant improvement in peak (P = .009) and mean (P = .001). Transcutaneous CO₂ parameters compared to conventional bilevel. Oxygenation on AVAPS showed positive trend but did not reach statistical significance. AVAPS delivered higher tidal volumes (P = .04) using similar pressures. There was no statistically significant difference in obstructive apnea-hypopnea index, respiratory arousal index, sleep efficiency, and adherence between AVAPS and conventional BPAP. AVAPS was an effective alternative to conventional BPAP in improving hypercarbia in our selective cohort of pediatric patients. Prospective, longitudinal studies are needed to evaluate the benefits of AVAPS feature in the pediatric population.

Effects of Sleep Fragmentation on the Arousability to Resistive Loading in NREM and REM Sleep in Normal Men

In healthy subjects, arousability to inspiratory resistive loading is greater during rapid eye movement (REM) sleep compared with non-REM (NREM) sleep but is poorest in REM sleep in patients with sleep apnea. We therefore examined the hypothesis that sleep fragmentation impairs arousability, especially from REM sleep. Two blocks of 3 polysomnographies (separated by at least 1 week) were performed randomly. An inspiratory-loaded night followed either 2 undisturbed control nights (LN(C)) or 2 acoustically fragmented nights (LN(F)) SETTING: Sleep laboratory. Sixteen healthy men aged 20 to 29 years. In both loaded nights, an inspiratory resistive load was added via a valved facemask every 2 minutes during sleep and turned off either when arousal occurred or after 2 minutes. During LN(F), arousability remained significantly greater in REM sleep (71% aroused within 2 minutes) compared with stage 2 (29%) or stage 3/4 (16%) sleep. After sleep fragmentation, arousability was decreased in stage 2 sleep (LN(F): 29%; LN(C): 38%; p < .05) and low in early REM sleep, increasing across the night (p < .01). In stage 3/4 sleep, neither an attenuation nor a change across the night was seen after sleep fragmentation. Mild sleep fragmentation is already sufficient to attenuate arousability in stage 2 sleep and to decrease arousability in early, compared with late, REM sleep. This means that sleep fragmentation affects the arousal response to increasing resistance and that the effects are different in stage 2 and REM sleep. The biologic reason for this increase in the arousal response in REM sleep across the night is not clear.

Temporal relationship between dynamic heart rate variability and electroencephalographic activity during sleep in man

In previous sleep studies, it has been demonstrated that Poincaré plots of RR intervals, which provide a beat to beat dynamic measure of heart rate variability, have distinctive and characteristic patterns according to sleep stages. This study was designed to evaluate the temporal relationship between heart rate variability and sleep electroencephalographic activity (EEG) by using the Pearson's interbeat autocorrelation coefficients of RR intervals derived from the Poincaré plots. The coefficients were calculated in 12 subjects over each minute and were related to the profiles of EEG mean frequency (0.5–35 Hz) computed using a Fast Fourier Transformation algorithm. Overnight profiles of interbeat autocorrelation coefficients and of EEG mean frequency were found to be related with highly significant cross-correlation coefficients ranging between 0.216 and 0.638 ( P<0.001). The variations in heart rate variability preceded changes in brain activity by 1–2 min. These results demonstrate that beat to beat heart rate variability and EEG activity are closely linked during sleep in normal man.

Changes in upper airway muscle activation and ventilation during phasic REM sleep in normal men

Several investigators have observed that irregular breathing occurs during rapid-eye-movement (REM) sleep in healthy subjects, with ventilatory suppression being prominent during active eye movements [phasic REM (PREM) sleep] as opposed to tonic REM (TREM) sleep, when ocular activity is absent and ventilation more regular. Inasmuch as considerable data suggest that rapid eye movements are a manifestation of sleep-induced neural events that may importantly influence respiratory neurons, we hypothesized that upper airway dilator muscle activation may also be suppressed during periods of active eye movements in REM sleep. We studied six normal men during single nocturnal sleep studies. Standard sleep-staging parameters, ventilation, and genioglossus and alae nasi electromyograms (EMG) were continuously recorded during the study. There were no significant differences in minute ventilation, tidal volume, or any index of genioglossus or alae nasi EMG amplitude between non-REM (NREM) and REM sleep, when REM was analyzed as a single sleep stage. Each breath during REM sleep was scored as "phasic" or "tonic," depending on its proximity to REM deflections on the electrooculogram. Comparison of all three sleep states (NREM, PREM, and TREM) revealed that peak inspiratory genioglossus and alae nasi EMG activities were significantly decreased during PREM sleep compared with TREM sleep [genioglossus (arbitrary units): NREM 49 +/- 12 (mean +/- SE), TREM 49 +/- 5, PREM 20 +/- 5 (P less than 0.05, PREM different from TREM and NREM); alae nasi: NREM 16 +/- 4, TREM 38 +/- 7, PREM 10 +/- 4 (P less than 0.05, PREM different from TREM)]. We also observed, as have others, that ventilation, tidal volume, and mean inspiratory airflow were significantly decreased and respiratory frequency was increased during PREM sleep compared with both TREM and NREM sleep. We conclude that hypoventilation occurs in concert with reduced upper airway dilator muscle activation during PREM sleep by mechanisms that remain to be established.

Ventilatory Responses to Added Deadspace during Sleep in Normal Men

Ventilatory Responses to Added Deadspace during Sleep in Normal Men

Nasal resistance during wakefulness and sleep in normal man.

Previously, we reported an increase in supralaryngeal resistance during sleep in normal man. Since nasal resistance is known to fluctuate over a wide range of circumstances, we hypothesized that the increase in supralaryngeal resistance observed was due to an increase in nasal resistance. Therefore, the purpose of this investigation was to examine changes in total and unilateral nasal resistance in five normal, adult males during wakefulness, Stage 2 (non-REM) sleep and REM sleep. Transnasal pressure and flow were measured for each side of the nose. Resistance was calculated from the slope of the linear portion of the transnasal pressure-flow relationship. During wakefulness and sleep, resistance was substantially higher on one side of the nose or unilateral total occlusion was present. This high resistance fluctuated from side to side during sleep. The transition of high resistance from side-to-side occurred rapidly. On turning to either side, the side of the nose with the high resistance was not necessarily the gravitationally-dependent side. Total nasal resistance did not change significantly during sleep. We concluded that 1) resistance on one side of the nose is usually considerably higher than the other side, 2) this high resistance side alternates during sleep as well as wakefulness, 3) since this alteration occurs rapidly and is not dependent on gravity, reflexes are likely involved and 4) changes in total nasal resistance were not responsible for the increased supralaryngeal resistance we have observed during sleep.

Respiration during sleep in normal man.

Respiratory volumes and timing have been measured in 19 healthy adults during wakefulness and sleep. Minute ventilation was significantly less (p less than 0.05) in all stages of sleep than when the subject was awake (7.66 +/- 0.34(SEM) 1/min), the level in rapid-eye-movement (REM) sleep (6.46 +/- 0.29 1/min) being significantly lower than in non-REM sleep (7.18 +/- 0.39 1/min). The breathing pattern during all stages of sleep was significantly more rapid and shallow than during wakefulness, tidal volume in REM sleep being reduced to 73% of the level during wakefulness. Mean inspiratory flow rate (VT/Ti), an index of inspiratory drive, was significantly lower in REM sleep than during wakefulness or non-REM sleep. Thus ventilation falls during sleep, the greatest reduction occurring during REM sleep, when there is a parallel reduction in inspiratory drive. Similar changes in ventilation may contribute to the REM-associated hypoxaemia observed in normal subjects and in patients with chronic obstructive pulmonary disease.

Hypoxic ventilatory response decreases during sleep in normal men.

Ventilatory drives are presumed to be important in the maintenance of ventilation during sleep. Although the hypercapnic ventilatory response has been shown to decrease during sleep, the hypoxic ventilatory response (HVR) has not been well studied in humans. We therefore measured the ventilatory response to isocapnic hypoxia in 6 sleeping men. The HVR, measured as the slope of the relation between ventilation and decreasing hemoglobin saturation, was significantly lower in all sleep stages than in wakefulness (1.07 +/- 0.19 SEM L/min/%saturation). The HVR decreased to two thirds of this waking value in non-REM sleep (0.63 +/- 0.09 L/min/%saturation) with a further significant decrease in REM sleep when HVR was less than one third of the waking value (0.33 +/- 0.04 L/min/%saturation). The decreased HVR may help to explain the REM-sleep-related hypoxemia found in normal persons and patients with various cardiovascular diseases.

Effects of promethazine on nocturnal sleep in normal man

The effects of a phenothiazine, on sleep in ten healthy volunteers were investigated in two double blind polygraphic studies. The first part consisted of a single dose study with promethazine 50, 100, and 200 mg, using pentobarbital 100 mg as a reference substance. In the second part, four subjects spent 20 consecutive nights with nine drug nights (promethazine 100 mg), followed by a placebo withdrawal period of six nights, in the sleep laboratory. Promethazine showed a dose related REM-depressing effect with a greater decrease, the higher the dose. The placebo value was 20.7% REM of total sleep time and gave 16.3, 13.5 and 11.4 respectively, for promethazine 50, 100 and 200 mg. Pentobarbital gave 16.2% REM. There was also an increase of stage II and with the highest dose an increase of stage III + IV. An increase of REM-latency together with a decrease of REM-periods was also seen, and while pentobarbital gave a decrease in REM-density, promethazine did not cause any changes in the phasic REM-component. A REM-rebound was seen in the first night of withdrawal with an increase of per cent REM from 19.9%-25.1%. The mean for the whole withdrawal period was 23.1%. Promethazine in the highest dose, 200 mg, gave drowsiness and hangover effects in 14 nights out of 20. The REM-depressing effect of promethazine together with its relatively weak REM-rebound effect may explain its value in the treatment of withdrawal symptoms following abuse of alcohol and barbiturates.

Effects of a new butyrophenone derivate (Buronil�) on nocturnal sleep in normal man

Nocturnal sleep was studied in eight young normal volunteers (3 female and 5 male students) with polygraphic technique during 2 periods of 10 night each. After 2 adaptation and 2 baseline nights with placebo, they were given methylperone (Buronil) 10 or 50 mg per night during three nights and then again placebo for three withdrawal nights. The study was made double blind. The scoring of the records was done according to the manual by Rechtschaffen and Kales (1968). No changes of sleep stages were seen during the drug periods. The lower dose gave an increase of sleep latency but a decrease of number of awakenings during the night. An increase of REM-periods was shown after 50 mg and also a decrease of REM-latency and REM-density. The only significant change during withdrawal periods was a decrease of REM-sleep after methylperone 50 mg, so there was no "barbiturate type" of withdrawal. The change was also different from that of chloropromazine, which has no clear rebound effect.

Plasma testosterone during nocturnal sleep in normal men

Plasma testosterone was measured by a competitive protein binding procedure at 10 to 20 minute intervals in five normal adult men during two nights of sleep. Blood samples were obtained by means of an indwelling venous catheter while sleep was monitored polygraphically. There were 1–4 abrupt elevations of plasma testosterone concentration per night in each of the subjects with an average increase of 244 ng/100 ml ± 45.5 (SE) or 59% above the values present at the onset of the episode. The fluctuations in plasma testosterone were superimposed on a nocturnal rise of the hormone observed in seven of the nights. The average of all samples taken during each hour period through the ten nights revealed a highly significant (P<0.001) nocturnal increase in plasma testosterone. The findings did not support the existence of a relation between REM sleep and an increase in testosterone levels.

The effects of hexapropymate upon sleep in normal man measured with a polygraphic technique

The effects of an ordinary clinical dose (400 mg) of hexapropymate (Mordirax®) on sleep were investigated in 16 young healthy volunteers by a polygraphic technique. Each subject was studied for two nights with the drug and for two reference nights with a placebo. The polygraphic recordings of EEG, neck EMG, oculogram and ECG were classified in different sleep stages and were scored according to international norms. — There were limited changes of sleep pattern during hexapropymate. REM sleep amounted to 22.1% for nights with placebo, and 19.8% for nights with hexapropymate; this difference is statistically significant at the 5 per cent level. A corresponding increase of Stage II sleep was found during hexapropymate nights (p<0.02). The drug caused an increase in REM-latency (p<0.05); the number of REM periods was unchanged. — The drug was shown to have hypnotic effects in this group of subjects all of whom were very good sleepers: total sleep time increased slightly, the sleep latency decreased and so did the number of nocturnal awakenings (p<0.002). — A digit-span-forward test, as well as the subject's own self ratings did not demonstrate any hang-over effects.