Biomedical subjects
M L Loren
Publications and source records attributed to M L Loren.
Effectiveness of a portable face mask in attenuating exercise-induced asthma.
Recent investigations have demonstrated that exercise-induced asthma (EIA) can be prevented by inspiration of warm, fully humidified air during exercise. We evaluated the success of a surgical face mask, used to retain warm, humidified, expired air, in preventing EIA in ten asthmatic children. subjects underwent six minutes of exercise on a treadmill during two sessions, in one session breathing room air and in another wearing a mask covering the nose and mouth. On the control day, average group forced expiratory volume in 1 s (FEV1) and maximal midexpiratory flow rate (MMEF) decreased from the preexercise baseline value to 66% and 47% of baseline, respectively, at six minutes; on the mask day, FEV1 and MMEF were 91% and 82% of the baseline values (increased in all subjects). A simple face mask may be an inexpensive, nonpharmacologic alternative for alleviation of EIA.
Comparison of two dosage schedules of sustained release theophylline in pediatric patients.
A sustained release theophylline preparation, administered on a q8h or q12h schedule, was evaluated in 12 severly asthmatic children. Total 24-hour theophylline dosage and peak theophylline levels were significantly higher during the q12h dosage schedule. Trough theophylline levels were similar with the two schedules. Four subjects on the q12h schedule had peak theophylline levels greater than 20 mcg/ml. Pulmonary functions, including FEV1 and MMEF, and the clinical stability of the patients were similar with the two regiments. Other than the higher peak theophylline levels that occurred with the q12h dosing schedule, there were no apparent differences noted between the dosage schedules.
Corticosteroids in the treatment of acute exacerbations of asthma.
In a 72-hour double-blind study 16 moderately to severely asthmatic subjects received either oral prednisone 2 mg/kg/day or placebo in addition to their regular medication as treatment for an acute exacerbation of asthma. The group receiving prednisone demonstrated significant increases in the PEFR and decreased need for beta-2 agonist nebulization or injections the first 12 hours of the study period and these improvements were maintained over the 72 hours. The placebo-treated group showed minimal reduction in nebulization and injection requirements and minimal increase in PEFR. Oral prednisone was found to be effective in controlling acute exacerbations of asthmatic symptoms.
Vascular ring presenting as asthma: the value of a flow-volume curve.
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Oral challenges in inhalant antigens in asthmatics.
Nine asthmatic children were sensitive to a variety of antigens by skin testing and bronchial inhalation challenges. On two separate occasions they received the antigens sublingually at 2.5 to 50 times the dose received by bronchial challenge. There were no subjective symptoms or objective changes in pulmonary function measurements following the oral challenges.
Irreversibility of obstructive changes in severe asthma in childhood.
The findings in three children with severe asthma are presented. Following intensive round-the-clock therapy with theophylline (the dosage of which maintained serum levels of theophylline between 10 microgram/ml and 20 microgram/ml) and therapy with prednisone (20 mg twice daily for three weeks or more), there were improvements in spirometric and body plethysmographic measurements. Despite this therapy, abnormalities in the forced expiratory volume in one second, the maximal midexpiratory flow, the residual volume, and specific airway conductance remained. These cases represent a subgroup of asthmatic children with reactive airways who have an irreversible component to their disease.
Age of onset in a group of severely asthmatic children.
The age of onset was examined retrospectively in a group of severely asthmatic children. The mean age of onset for males was 29.4 +/- 22.7 months and 30.4 +/- 27.0 months for females. The distribution of age of onset between males and females was remarkably similar (X2 = 1.77, 0.6 less than p less than 0.9). The mean age of onset was similar in children not receiving corticosteroids compared to those children who were taking high and low dose corticosteroids. An early or late age of onset appeared independent of corticosteroid requirements. Children with five or more positive immediate skin tests had earlier age of onset and higher total serum IgE levels than those with four or fewer positive skin tests.
Pulmonary sequelae in low-birth-weight infants.
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