Congenital heart malformations and ventilatory efficiency in children. Effects of lung perfusion during halothane anaesthesia and spontaneous breathing.
The efficiency of spontaneous ventilation during halothane anaesthesia was investigated in 18 infants and children with congenital heart disease presenting either with hyperperfusion and left-to-right shunt (group LR: n = 10, body weight 3.7-16 kg) or with hypoperfusion and right-to-left shunt (group RL: n = 8, body weight 3.4-12 kg). Minute ventilation (VE) and tidal volume (VT) were greater in group RL than in group LR (P less than 0.05) while ventilatory rates were similar. Dynamic compliance and total pulmonary resistance were of the same magnitude in the two groups. Alveolar ventilation (VA) calculated from arterial carbon dioxide tensions (PaCO2) was the same in both groups while corresponding deadspace ventilation (VD) was higher in group RL (P less than 0.01). VE/VCO2 and VD/VT ratios were higher in children with a diminished pulmonary blood flow than in children with an increased pulmonary blood flow (P less than 0.05 and P less than 0.01, respectively) indicating a less efficient gas exchange in children with a right-to-left shunt. This was compensated for by an increased inspiratory drive as reflected by higher VT/TI ratio (P less than 0.01) and a more pronounced airway occlusion pressure (P less than 0.05).
D000769:Anesthesia, Inhalation; D002675:Child, Preschool; D006221:Halothane / Q000494:pharmacology; D006330:Heart Defects, Congenital / Q000503:physiopathology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D011659:Pulmonary Gas Exchange; D012119:Respiration / Q000187:drug effects*; D012129:Respiratory Function Tests
D006221:Halothane