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Abstract. A disorder of respiratory control is the suspected etiology in a majority of infants with apnea. Although neurologic control of breathing has been evaluated in infants surviving an apneic episode, pulmonary mechanics have not been previously measured. Pulmonary mechanics were measured during sleep in ten infants with apnea, aged 45.4 +/- 1.4 (SE) weeks postconception, and 13 control infants, aged 42.0 +/- 0.8 weeks postconception. Infant apnea patients were defined as those having at least one episode of cyanosis, limpness, and apnea requiring vigorous stimulation or resuscitation to restore normal breathing, and in whom no treatable etiology could be found. Thoracic gas volume, airway resistance, and specific airway conductance were measured in an infant body pressure plethysmograph during quiet breathing. Dynamic pulmonary compliance was measured in six infants using an esophageal balloon. Specific airway conductance was decreased in infants with apnea compared with control infants (P < .05). Thoracic gas volume, airway resistance, and dynamic pulmonary compliance values were comparable with those of control infants. These data suggest that airway narrowing or abnormal control of airway tone during sleep may contribute to apnea in some infants. [ABSTRACT FROM AUTHOR]

Abstract. In a randomized double-blind crossover trial with sequential analysis, the effects of oral diuretics were compared with the effects of placebo on pulmonary mechanics in ten infants with bronchopulmonary dysplasia (BPD). Pulmonary mechanics were measured before and at the end of a week of treatment with oral diuretics (chlorothiazide, 20 mg/kg/dose and spironolactone, 1.5 mg/kg/dose) given twice daily, or placebo. Mean airway resistance decreased 35.3 cm H[sub 2]O/L/s, mean specific airway conductance increased 0.095 1/L/s/cm H[sub 2]0, and mean dynamic pulmonary compliance increased 1.74 mL/ cm H[sub 2]O during treatment with diuretics (all P <.001), but not during treatment with placebo. The infants' rate of weight gain decreased on the first three days of diuretic treatment, but was thereafter comparable with weight gain during treatment with placebo. Fluid intake was similar in infants receiving diuretics and placebo. But, infants receiving diuretics not only had significantly increased urine output, osmolal clearance, and potassium and phosphorus excretion, but these infants also retained less fluid, and, in addition, excreted less calcium than infants receiving placebo. It is concluded that oral diuretics improve lung function in infants with chronic bronchopulmonary dysplasia; however, potassium and phosphorus depletion are potential complications of treatment. [ABSTRACT FROM AUTHOR]

Abstract. The effects of isoproterenol inhalation on pulmonary mechanics in ten infants with bronchopulmonary dysplasia (BPD), aged 41 +/- 1 (SE) weeks postconception, with gestational age at birth 30 +/- 1 weeks, and birth weight 1,590 +/- 200 g were studied. The infants had: (1) hyaline membrane disease requiring mechanical ventilation in the first five days of life, (2) mechanical ventilation and/or FIo[sub 2] greater than 30% for at least 30 days, and (3) stage III or IV radiographic changes. Thoracic gas volume, airway resistance, and specific airway conductance were measured in an infant body pressure plethysmograph during quiet breathing. Dynamic pulmonary compliance was measured using an esophageal balloon. These infants with BPD had greater airway resistance, lower specific airway conductance, and lower dynamic pulmonary compliance than 16 normal control infants (age 40 +/- 1 weeks postconception). In the infants with BPD, measurements were obtained before and 1/2, 1, 2, and 6 hours after the administration of isoproterenol aerosol 0.1% inhalation or saline aerosol placebo, five breaths by slow inflation of the lungs with an anesthesia bag. Within 30 minutes after isoproterenol inhalation, airway resistance decreased 28% +/- 5% and specific airway conductance increased 53% +/- 15%. Thoracic gas volume and dynamic pulmonary compliance did not change. There were no changes following administration of the placebo. Isoproterenol inhalation is associated with rapid short-term improvement in airway resistance and specific airway conductance in infants with BPD. Pediatrics 1984;73:509-514; isoproterenol, bronchodilator, airway resistance, bronchopulmonary dysplasia, specific airway conductance. [ABSTRACT FROM AUTHOR]