Pediatric pulmonology
-
Pediatric pulmonology · Jan 1991
Comparative StudyPulse oximetry versus measured arterial oxygen saturation: a comparison of the Nellcor N100 and the Biox III.
Pulse oximetry is noninvasive, fast, and simple, making it a very popular way of assessing oxygenation in pediatric patients. However, there are few studies that establish the accuracy of this technology over a wide range of oxygen saturations in children. This study, done in 47 children aged from 1 day to 16 years with congenital heart disease and undergoing cardiac catheterization, compared the direct measurement of arterial oxygen saturation to values from pulse oximetry. ⋯ For both devices, the error increased with decreasing saturations, being progressively larger below a saturation of 80%. The difference between the actual saturation and that measured by pulse oximetry bore no relationship to the presence of carboxyhemoglobin, methemoglobin, fetal hemoglobin, bilirubin, cardiac index, or age of the patient. In conclusion, pulse oximetry, while a very useful technology in pediatrics, must be interpreted with some caution in children with severe cyanosis.
-
Pediatric pulmonology · Jan 1991
Birthweight, early passive respiratory system mechanics, and ventilator requirements as predictors of outcome in premature infants with respiratory failure.
Early respiratory mechanics have been reported to predict outcome in newborns with respiratory failure. However, it remains unknown whether measurements of pulmonary function add significantly to the predictive value of more readily available variables The present study was designed to answer this question. Passive respiratory system mechanics were measured by an airway occlusion technique in 104 ventilator-dependent premature infants between 6 and 48 hours of life and corrected for infant size. ⋯ Respiratory system conductance (P = 0.15) and compliance (P = 0.93) entered on the third and last step, respectively. We conclude that in premature infants with respiratory failure, birthweight is a strong predictor of outcome. Early ventilator requirements but not respiratory system mechanics, add significantly to this predictive model.
-
Pediatric pulmonology · Jan 1991
Relationship of symptoms to lung function abnormalities in preterm infants at follow-up.
Recurrent respiratory symptoms are common in preterm infants in the first 2 years of life. The aim of this study was to determine the lung function abnormalities associated with such symptoms. Forty preterm infants, with a median gestational age of 29 weeks were studied at a median postnatal age of 12 months. ⋯ Lung function was assessed by measurement of functional residual capacity (FRC), using a helium gas dilution technique, and airway resistance (Raw) and thoracic gas volume (TGV) plethysmographically. No significant difference was found in TGV between symptomatic and asymptomatic infants, but the median FRC was lower (P less than 0.01), Raw higher (P less than 0.01), and FRC:TGV ratio lower (P less than 0.001) in the symptomatic infants. These lung function abnormalities in the symptomatic infants are suggestive of gas trapping.
-
Pediatric pulmonology · Jan 1991
Effects of endotracheal tube size and ventilator settings on the mechanics of a test system during intermittent flow ventilation.
The effect of varying the size of standard neonatal endotracheal tubes on delivered tidal volumes (VT), resistance (R), dynamic compliance (Cdyn), and resistive work of breathing (WOB) was measured in a test system during intermittent flow ventilation at different ventilator settings. The experiments were performed with a Sechrist infant ventilator connected to a Dräger Test Lung via standard neonatal endotracheal tubes. R, inspiratory (Ri), and expiratory resistance (Re) as well as WOB were significantly affected by endotracheal tube size. ⋯ Also, ventilator settings with respect to the peak inspiratory pressure (PIP) - positive end-expiratory pressure (PEEP) difference had a significant influence on Cdyn for both tube sizes. On the other hand, flow and inspiratory time adjustments had no significant effect on ventilatory parameters. Endotracheal tube size and ventilator settings should be considered when comparing the pulmonary function tests in intubated and non-intubated newborn infants.
-
Pediatric pulmonology · Jan 1991
The effect of lung mechanics on gas transport during high-frequency oscillation.
With the general aim of obtaining clinically relevant information on the use of high-frequency oscillation (HFO), we examined the effects of altering oscillatory frequency (f), tidal volume (VT), and mean airway pressure (Paw) on gas exchange in rabbits, both before and after altering the animal's pulmonary mechanics by saline induced lung injury. Twenty-seven combinations of f (5, 8, 12 Hz), VT (0.5, 1, 2 mL/kg), and Paw (5, 10, 13 cm H2O) were used. Acute pulmonary injury was induced by instilling 10 mL/kg of warm saline into the lung. ⋯ VTb where the exponents a = -0.4 and b = -0.6. Our technique of a standardized saline instillation gave a reproducible and stable model of lung injury. In damaged rabbit lungs the principles of HFO appear to be similar to conventional mechanical ventilation; oxygenation depends on Paw and inspired oxygen concentration, while CO2 removal is determined by f and VT.