Spontaneous versus controlled ventilation in anaesthetized children with congenital cardiac malformations.
The effects of intermittent positive pressure ventilation on gas exchange were studied in 12 children with congenital cardiac malformation. Six children (b.w. 3.7-16 kg) had a left-to-right shunt (Group LR) resulting in overperfused lungs, while six others (b.w. 3.4-12 kg) had a right-to-left shunt (Group RL) with oligaemic lungs. Measurements, prior to surgery, were done during spontaneous breathing (SB) and controlled mechanical ventilation (CMV) with a short (25%) and a long (55%) duration of inspiration. In children with oligaemic lungs P(a-E')CO2 differences and VD/VT ratios were greater and PaO2 was lower than in those with overperfused lungs, indicating a less efficient ventilation. In Group RL, ventilation and gas exchange during SB were similar at the two settings of CMV. In Group LR, however, VD/VT was reduced during CMV, with the lowest VD/VT ratio at the longer inspiration time. It is concluded that in children with an oligaemic lung perfusion, either of the two ventilator settings could be used. When controlled ventilation is to be used in children with overperfused lungs, the longer duration of inspiration seems to be preferable.
D000768:Anesthesia, General; D002675:Child, Preschool; D005283:Fentanyl; D006221:Halothane; D006330:Heart Defects, Congenital / Q000601:surgery*; D006801:Humans; D007223:Infant; D008168:Lung / Q000098:blood supply; D009609:Nitrous Oxide; D011175:Positive-Pressure Respiration; D011659:Pulmonary Gas Exchange; D012119:Respiration
D009609:Nitrous Oxide; D005283:Fentanyl; D006221:Halothane