A Method for Ventilatory Measurements in Subjects 1 Month-5 Years of Age: Normal Results and Observations in Disease

Abstract

ExtractUsing the total body plethysmograph, a method for the measurement of lung volume and airway resistance was developed for infants and young children of 1 month-5 years of age. The subjects were studied in a supine position using a reproducible method of sedation. The procedure providing the most consistent results involved use of a Rendell-Baker mask directly controlled by the operator while the subjects were breathing through the nose. Availability of an oscilloscope permitted immediate detection of pressure leaks, artifacts, and abnormal patterns during each determination and minimized potential errors during the study of each subject. Care was required to avoid pressure on the tip of the nose because an abnormally high airway resistance resulted.The logarithmic relation of thoracic gas volume (TGV) at functional residual capacity (FRC) to body length for 52 normal subjects compared well with results obtained on newborn infants and with those obtained on older subjects. The equation was: TGV at FRC, liters = 1.57 x 10-5 x length, cm 2.238 (correlation coefficient = 0.948). The logarithmic relation of airway conductance to TGV was: conductance, liters/sec/cm H,O = 0.1431 TGV, liters 0 . 6441 (correlation coefficient = 0.835). Comparison with older subjects was limited by the difference in airflow rates at which the airway conductance was determined (0.06-0.28 literslsec versus about 0.5 literslsec for adults) and by the use of sedation and nasal breathing in this study; adults are studied awake and during mouth breathing. Comparison of our conductance values with those obtained on unsedated newborns suggests that either sedation alters the airway resistance or that some change occurs in the airway size-lung volume relation during the first weeks of life.Examples of the application of this method to patients with asthmatic bronchitis and cystic fibrosis of the pancreas are provided. SpeculationIt is possible that an airflow-lung volume-airway resistance relation exists throughout life; however, the results presented in this study, combined with those previously presented on newborns for airway resistance, suggest that a change may occur in the relation of the size of the airways to lung volume during early infancy, or that sedation alters airway resistance. Development of this and other methodology should permit more adequate studies of the early changes in pulmonary physiology associated with growth and the acute and chronic pulmonary conditions seen during the first 5 years of life. DOERSHUK, DOWNS, MATTHEWS and LOUGH

Pulmonary Mechanics in Early Infancy. Sublinical Grunting in Low-Birth-Weight Infants

“…As in our previous study, the values of pulmonary functions reported in this work showed good agreement with data in other studies (3,5,7,10,11,15). The increased ventilation during carbon dioxide-induced hyperventilation was due mainly to an increased tidal volume.…”

“…Strong linear relationships have been shown between resistance or conductance and lung volumes in other studies (5,13). We have tried to measure lung volumes with the body plethysmograph and gas dilution techniques but did not succeed because the unsedated infants were awakened by the experimental manipulations.…”

“…Pulmonary mechanics studies have been reported for both newborn (3,4,7,8,13,14) and older infants (5,10,11,13,15). In a previous study of pulmonary mechanics, we studied 26 infants during the first year of life (2).…”

Changes in Respiratory Pattern Resulting from the Use of a Facemask to Record Respiration in Newborn Infants

“…Similar results have been reported in awake adult man (2). Such changes could be caused by an increase in airway resistance due to partial airway obstruction (4) or to the flow resistance of the pneumotachograph. The latter explanation is unlikely, as flow resistance through the mask and pneumotachograph was very low-less than 10% of the expected total airway resistance (8)-and comparable to values published for other mask or pneumotachograph techniques (9, 10).…”

Functional residual capacity in healthy preschool children

“…The mean tidal volume was equal during two consecutive measurements as was the respiratory rate. The mean tidal volume of 17.1 mL·kg -1 is higher than the 12.0 and 8.8 mL·kg -1 observed by TAUSSIG et al [7] and by DOERSHUK et al [16], respectively. In the study by DOERSHUK et al [16], the children were sedated, which may reduce the tidal volume [5].…”