Pulmonary function following positive pressure ventilation initiated immediately after birth in infants with respiratory distress syndrome

Abstract

Cardiopulmonary function following positive pressure ventilation, initiated immediately after birth, was evaluated in 10 very low birthweight infants with respiratory distress syndrome (RDS; RDS infants). Multiple gas rebreathing methodology was used to measure functional residual capacity (FRC), diffusing capacity of the lung for carbon monoxide (DLCO) and effective pulmonary capillary blood flow (Qeff) at 2, 24, and 72 hr of age. Cardiopulmonary function variables were also measured at 2 hr of age in 10 infants of similar birthweight who did not have RDS (non-RDS infants). In RDS infants, mean FRC at both 2 hr of age (15 mL/kg or 0.42 mL/cm) and 24 hours of age (20 mL/kg or 0.54 mL/cm) was less than published predicted values for healthy infants and significantly less than values in non-RDS infants at 2 hours of age (29 mL/kg or 0.8 mL/cm). By 72 hr of age, mean FRC in RDS infants rose to predicted. At 2 and 24 hours of age, mean Qeff in RDS infants (41 and 38 mL/min/kg, respectively) was below predicted, as well as below the value observed in non-RDS infants at 2 hr of age (62 mL/min/kg). in RDS infants. DLCO remained well below published predicted values throughout the first three days of life. We conclude that early aggressive respiratory therapy does not result in the establishment of normal lung volumes during the first day of life, but it does so by 3 days of age. However, in spite of intubation immediately after birth and the application of continuous positive pressure ventilation during the first 3 days of life, very low birthweight infants with RDS continue to have significant alteration in lung function, evidenced by impaired diffusing capacity of the lung and low arterial-alveolar oxygen tension ratios.

Mechanics of Breathing after Surgical Ligation of Patent Ductus arteriosus in Newborns with Respiratory Distress Syndrome

“…The MAP before ligation of the PDA was elevated and close to that quoted in the literature for newborns with RDS [7,25]. After surgical intervention, MAP dropped slightly, which was probably due to lowering of parameters of mechanical ventilation.…”

Measurement of lung volume and optimal oxygenation during high frequency oscillation.

“…We were therefore not surprised to find a variable response to HFO. If an infant has atelectatic lungs, the lung must be inflated above the pressure at which it opens and then be maintained above its closing pressure for oxygenation to improve.2 Although increasing 14 MAP on conventional ventilation, compared with HFO, could achieve the same results, this would be more likely to increase complications as a result of barotrauma. An increase in MAP to improve oxygenation, however, is only relevant when the lung volume is low.…”

Measurement of Functional Residual Capacity by Sulfur Hexafluoride in Small-Volume Lungs during Spontaneous Breathing and Mechanical Ventilation

“…For measurements with the open circuit nitrogen washout technique (18,19), the infant also has to be connected to a second ventilator. The bag-in-bottle rebreathing systems either have to use CO 2 absorbers in the circuit (20) or can only allow for a short period of equilibration, which might be too short for diseased lungs (21,22). Recently described modified plethysmographic techniques also still appear cumbersome because the patient has to be moved into a box sealed around the face (23)(24)(25)(26).…”