Oxygen therapy using pulse and continuous flow with a transtracheal catheter and a nasal cannula.

Pulse delivery (PD) of oxygen was compared with continuous flow (CF) utilizing transtracheal oxygen catheter (TTO) and nasal cannula (NC) in 20 stable patients with chronic hypoxemia. Oxygen saturation, respiratory rate, and accuracy of pulsed oxygen delivery were measured during sleep studies and these parameters, as well as arterial blood gases, were evaluated during rest and exercise. Additionally, bulk liquid oxygen use was measured under each condition, for a period of 1 month. Pulse delivery NC was evaluated in six subjects, CF NC in 14 subjects, and PD and CF TTO in 20 subjects over the 1-month period. Results showed that, as a group, patients were adequately oxygenated when utilizing the PD with both NC and TTO as assessed by arterial blood gases, oximetry, and hematocrit. However, four subjects could not be adequately oxygenated on PD NC during exercise even at the maximum liter per minute setting and could not be studied with this mode of therapy. The PD settings in the remaining subjects were equivalent to continuous flow settings for TTO and NC as assessed by PaO2 for rest and SaO2 for exercise and sleep. Compared with standard CF NC, the daily bulk oxygen use was decreased by 29.4 percent with CF TTO, by 48.2 percent with PD NC, and by 49.9 percent with PD TTO. We conclude that, compared with CF NC, PD of oxygen via TTO or NC by this method appears to be a safe, reliable, effective, and cost-effective method of oxygen delivery in the majority of subjects when used with proper screening.

Gastroesophageal reflux with drifting onset in infants: a phenomenon unique to sleep.

We have characterized the gastroesophageal reflux (GER) episodes which occurred during sleep in 28 infants with pathologic gastroesophageal reflux and 10 symptomatic age-matched controls without gastroesophageal reflux. We describe three kinds of episodes during the sleeping period-awake episodes which occur completely during electroencephalogram (EEG)-defined wakefulness associated with clinical evidence of the waking state (62 episodes), episodes occurring during EEG-defined sleep which have a rapid drop in pH at their onset (119 episodes), and episodes occurring during EEG-defined sleep in which the esophageal pH drifts down slowly over a period up to 30 min (113 episodes). Only 9 of the 10 control subjects experienced any reflux episodes during monitoring. The total number of episodes of reflux in controls (34) was less than the total number in reflux subjects (260). Controls did, however, experience all three types of reflux episode. Awake episodes all had a rapid drop in pH at their onset and were characterized by a short acid clearance time (2.0 +/- 0.3 min in reflux patients and 1.0 +/- 0.2 min in controls). The sleep episodes with rapid onset had longer mean acid clearance time than the awake episodes, significantly so in GER subjects (20.1 +/- 6.8 min in reflux subjects and 2.6 + 1.3 min in controls). Body movement was noted at the onset of 93.4% of rapid-onset sleep episodes in reflux subjects and 88.9% in controls. Body movement was also common at the termination of rapid-onset sleep episodes (77.8% of rapid-onset episodes in reflux subjects and 80.0% in controls).(ABSTRACT TRUNCATED AT 250 WORDS)

Electroencephalogram patterns during sleep reflux in infants.

Twenty-four infants, 3-35 months of age, with histories of apnea or chronic lung disease underwent nighttime polysomnography and esophageal pH monitoring. Fifteen infants had pathological levels of gastroesophageal reflux on esophageal pH monitoring, and 9 had normal study results (symptomatic controls). Partition of sleep stages, sleep efficiency, and frequency of arousals to electroencephalographic stage 0 were the same in both groups. During sleeping reflux episodes, defined as reflux starting during sleep stages 1-5 or reflux episodes consisting of greater than 50% of sleep stages 1-5, there was a 50% decrease in the amount of stage 0 electroencephalogram pattern compared with nonreflux sleep, and a compensatory increase in the non-rapid eye movement sleep stages. Reflux onsets in patients with pathological reflux were evenly divided between stages 0, 1/2, and 5. Onset of reflux occurred rarely during sleep stages 3 and 4. Slight body movement accompanied the onset of 62.5% of sleep reflux episodes in symptomatic controls and 64.7% in patients with pathological gastroesophageal reflux. Arousals to stage 0 electroencephalogram occurred with equal frequency in sleep reflux episodes of symptomatic controls and patients, and frequency did not increase over the observed value for nonreflux time. There were no differences between the sleep patterns of infants with and without pathological gastroesophageal reflux; nor were there decreases in arousals from sleep in infants with pathological reflux. However, reflux occurring during sleep in all infants studied was characterized by a significant decrease in stage 0 (waking) electroencephalogram.

Obstructive sleep apnea syndrome: preoperative radiologic evaluation.

The purpose of this study was to determine whether lateral radiographs of the pharynx and fluoroscopy of the lateral pharynx in the sleeping patient could be used as predictors of surgical success in patients undergoing soft-palate surgery for obstructive sleep apnea. A total of 12 patients had surgery after radiologic evaluation. There were six surgical successes and six failures. No successes occurred in patients with a soft-palate length of less than 46 mm, nor were there any successes among patients whose initial point of obstruction on fluoroscopy was inferior to the level of the soft palate. There was one surgical failure among patients in whom fluoroscopy showed upper airway obstruction beginning at the level of the soft palate during sleep. Results suggest that a patient is most likely to benefit from soft-palate resection if the soft palate is long--we conservatively suggest greater than 40 mm--and if sleep fluoroscopy of the lateral pharynx shows airway obstruction beginning at the level of the soft palate.

Efficacy without tolerance or rebound insomnia for midazolam and temazepam after use for one to three months.

Midazolam (15 mg) was compared with temazepam (30 mg) in a randomized, double-blind, parallel group study. An initial screening period was followed by 3 days of placebo baseline, 4 to 12 weeks of nightly oral use of the medication and a 4-day placebo withdrawal period. One hundred seventy-five patients with chronic insomnia participated in this multicenter outpatient study. Because the elimination half-life of midazolam, a new trizolobenzodiazepine hypnotic, is short (1.3-2.2 hr) compared to temazepam's (12-16 hr), more problems with tolerance and rebound insomnia were expected to occur. Hypnotic efficacy (increased total sleep time, decreased wake time, and decreased sleep latency) was demonstrated for both medications over the entire 3-month period without the development of tolerance. In fact, if anything, efficacy increased with time on medication, suggesting possible facilitation or "inverse tolerance" effect. On withdrawal, sleep was improved compared with baseline, suggesting partial resolution of the insomniac condition rather than rebound insomnia. These effects were both statistically and clinically significant for midazolam, with 16% to 50% improvement in sleep measures. The results of this study suggest that patients with chronic insomnia may benefit from 30 to 90 days of treatment. A three-factor model that separates pharmacologic from behavioral and psychologic effects of hypnotics was proposed to explain these results in part.

Effect of growth hormone on memory in mice.

In order to determine the effects of growth hormone (GH) on long term memory, two experiments were carried out, all involving a common paradigm. Mice were given massed training on a discrimination task and were injected with GH or control substances before and/or after training: retention was measured 4 weeks later. In Experiment 1, different groups of mice were injected with either GH or saline at five different time points relative to original learning (OL): 90, 30, and 5 min before, and 5 and 30 min after. The results showed a significant quadratic trend, in the form of a U-shaped curve for the GH-injected groups at retention. Maximal retention was observed at the 90 min pre-OL and the 30 min post-OL injection groups. Poorest retention was shown by the 5 min pre-OL injection group. In Experiment 2, GH, saline, and thyroid-stimulating hormone (TSH) were administered at 90 and 5 min pre-OL. In addition, a "state dependency" hypothesis was tested using additional groups of mice. The results again showed a severe drop in retention when GH was administered 5 min before OL; differences between the two pre-OL GH injection groups were less marked than in Experiment 1; TSH did not have the same action as GH; and finally, a state dependency interpretation was ruled out. Together the two experiments present results that indicate a selectively GH-induced suppression of memory when GH is administered in close proximity to OL. As the time lapse between the injection of drug and the learning task increases, the inhibitory effect on memory is reversed.

Effects of 5-hydroxytryptophan on fragmentation of REM sleep in alcoholics.

The authors studied the effects of oral loading with 5-HTP on REM fragmentation in a group of alcoholics who were abstinent following acute ethanol withdrawal. Decreased fragmentation was found in the majority of subjects, and those subjects with low baseline REM efficiency (i.e., greater fragmentation) showed more improvement from the drug than did subjects who were less impaired initially. The authors suggest that there is an organic decrement of serotonin during ethanol withdrawal which is partially reversed by 5-HTP loading.