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Pulmonary mechanics were studied with the constant pressure body plethysmograph method in 78 infants during the first year of life. Registrations of breathing frequency, tidal volume, minute volume, dynamic compliance, pulmonary functional resistance, and end-expiratory resistance were made at rest and during carbon dioxide-induced hyperventilation. Data from 70 infants demonstrated strong correlations (P< 0.001) between all pulmonary function parameters and length. Carbon dioxide-induced hyperventilation was achieved mainly by an increased tidal volume. Pulmonary functional resistance did not change with hyperventilation, indicating wider airways during forced ventilation.

Summary: Pulmonary mechanics were studied with the constant pressure body plethysmograph method in 78 infants during the first year of life. Registrations of breathing frequency, tidal volume, minute volume, dynamic compliance, pulmonary functional resistance, and end-expiratory resistance were made at rest and during carbon dioxide-induced hyperventilation. Data from 70 infants demonstrated strong correlations (P < 0.001) between all pulmonary function parameters and length. Carbon dioxide-induced hyperventilation was achieved mainly by an increased tidal volume. Pulmonary functional resistance did not change with hyperventilation, indicating wider airways during forced ventilation.A special breathing pattern called “subclinical grunting” was found in 16 of 45 infants who were low birth weight but without clinical signs of hyaline membrane disease. The pattern was characterized by a high resistance during most of the prolonged expiration. It was identical to that previously described in cases of hyaline membrane diseases. All re-examined low-birth-weight infants with subclinical grunting developed a normal breathing pattern.Speculation: Sublinical grunting found in preterm low-birth-weight infants might be a phenomenon of postnatal lung adaptation which can be registered by pulmonary mechanics examination.

Most ligand-receptor interactions result in an immediate generation of various second messengers and a subsequent association of the ligand-receptor complex to the cytoskeleton. Depending on the receptor involved, this linkage to the cytoskeleton has been suggested to play a role in the termination of second messenger generation and/or the endocytic process whereby the ligand-receptor complex is internalized. We have studied how the binding of chemotactic peptide-receptor complexes to the cytoskeleton of human neutrophils is accomplished. As much as 76% of the tritiated formylmethionyl-leucyl-phenylalanine (fMet-Leu-[3H]Phe) specifically bound to intact cells, obtained by a 30-s stimulation with 20 nM fMet-Leu-[3H]Phe, still remained after Triton X-100 extraction. Preincubating intact cells with dihydrocytochalasin B (dhCB) or washing the cytoskeletal preparation with a high concentration of potassium, reduced the binding of ligand-receptor complexes to the cytoskeleton by 46% or more. Inhibition of fMet-Leu-Phe-induced generation of second messengers by ADP-ribosylating the alpha-subunit of the receptor-coupled G-protein with pertussis toxin, did not reduce the binding of ligand-receptor complexes to the cytoskeleton. However, using guanosine-5'-O-(2-thiodiphosphate) (GDP beta S) to prevent the dissociation of the fMet-Leu-Phe-associated G-protein within electrically permeabilized cells, led to a pronounced reduction (62%) of the binding between ligand-receptor complexes and the cytoskeleton. In summary, in human neutrophils the rapid association between chemotactic peptide-receptor complexes and the cytoskeleton is dependent on filamentous actin. This association is most likely regulated by the activation and dissociation of the fMet-Leu-Phe-associated G-protein.

Some physical effects of CPAP are discussed, as are the various devices used for CPAP in infants. Some of the controversies about CPAP may be related to the unsuitability of certain techniques. Use in hyaline membrane disease, extrathoracic and intrathoracic airway obstruction, congestion or overperfusion of the lungs in diseases of the heart and great vessels, apnea repetens of immaturity, and phrenic nerve palsy is presented.

Forty-one low weight premature infants treated with intermittent positive pressure ventilation in infancy were followed clinically and with chest radiography for 4 to 6 years. One child died during the period (sudden infantile death) and 2 others were not available for follow-up examination. The abnormal chest pattern of bronchopulmonary dysplasia (BPD) resolved completely or improved during the period; residual changes were found in 34 per cent of the cases. The main part of the resolution occurred during the first 2 years. Mild BPD was more prone to heal. The persisting parenchymal changes—interstitial fibrosis or areas of hyperinflation or both—were generally slight. The frequency of infection of the lower respiratory tract was increased during the first 2 years of life and was positively correlated to the severity of the pulmonary abnormalities. The frequency of infection dramatically decreased during the subsequent 2 years.