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Biomedical subjects

L G Brownell

Publications and source records attributed to L G Brownell.

5 recordsLinked to original sources

Breathing during sleep in normal pregnant women.

Physiologic changes during the last trimester of pregnancy include reduced functional residual capacity and residual volume, increased alveolar-arterial difference for oxygen, and in the supine position reduced cardiac output. In conjunction with sleep-related apnea or hypoventilation, these could lead to maternal oxygen desaturation during sleep. Because we could not find detailed respiratory sleep studies in late pregnancy, we performed complete polysomnography on 6 pregnant women at 36 wk gestation and again postpartum. Contrary to what we expected, oxygenation was well maintained, with neither mean nor minimal arterial oxygen saturation significantly different during pregnancy. Frequency of apnea and hypopnea and total apnea and hypopnea time were significantly reduced during pregnancy. This finding may be due to increased levels of progesterone during pregnancy and may contribute to preservation of maternal oxygenation during late pregnancy.

Apnea↗

Protriptyline in obstructive sleep apnea: a double-blind trial.

We evaluated protriptyline, a nonsedating tricyclic antidepressant, as a treatment for obstructive sleep apnea in a double-blind crossover study of five men. After two weeks of treatment, with no change in body weight, daytime somnolence was markedly reduced and nocturnal oxygenation was improved, although apnea duration and frequency were not significantly decreased. Rapid-eye-movement (REM) stage time as a fraction of the total sleep time was reduced during treatment from 0.231 +/- 0.031 to 0.107 +/- 0.013 (mean +/- S.E.M.) (P less than 0.05). REM apnea time as a fraction of total sleep time was reduced from 0.145 +/- 0.022 to 0.054 +/- 0.006 (P less than 0.05). REM reduction during treatment with protriptyline can account for decreased REM apnea time. Similar decreases in REM stage time and REM apnea duration and similar improvement in oxygenation continued after six months of treatment. In addition, body weight, apnea, and arousal frequency were decreased at this time. Although the obstructive sleep apnea was not resolved, it was reduced. Protriptyline can be effective in patients with sleep apnea when the disorder is not life-threatening.

Adult↗

Inheritance of hypoplastic left heart syndrome (HLHS): further observations.

From a survey of newborn infants using truncate ascertainment of families through affected offspring, 64 cases of hypoplastic left heart syndrome (HLHS) were found. Pedigree information was obtained from 42 families. The incidence of HLHS, based on 64 affected infants, was 36.5/100,000 births. The incidence of HLHS with aortic and/or mitral atresia was 25.1/100,000 births. The recurrence among later siblings was about 2 %. Autosomal recessive hypothesis of transmission of this disorder was not supported. Using Edwards' formula, the observed recurrence among later siblings was compatible with polygenic inheritance.

Canada↗

The role of protriptyline in obstructive sleep apnea.

Protriptyline, a non-sedating tricyclic agent, was evaluated in a double blind drug-placebo crossover trial in five obese patients with obstructive sleep apnea. Four of the five patients had improvement in somnolence. Protriptyline improved oxygenation. This seemed related primarily to a reduction (from 23% to 11%) in REM, with fewer of the more severe REM apneas. Arousal frequency remained quite high; thus the reason for the reduction in somnolence remains unclear. In three patients, at six months the improvement in clinical status and oxygenation persisted. We have now attempted long term treatment in nine patients. In five, anticholinergic side-effects necessitated stopping therapy. Four patients continue to do well. A trial of protriptyline is thus indicated in treatment of mild to moderate obstructive apnea or when the patient refuses more invasive treatment.

Adult↗