EFFECT OF POSITIVE END-EXPIRATORY PRESSURE AND MEAN AIRWAY PRESSURE ON RESPIRATORY COMPLIANCE AND GAS-EXCHANGE IN CHILDREN WITH LIVER-DISEASE

The effect of positive end expiratory pressure (PEEP) and mean airway pressure (MAP) on respiratory compliance and gas exchange was assessed in children with liver disease. In the first study of 12 patients, PE EP was decreased either by 3 cmH(2)O below the baseline level (the chi ld's original level) or to O cmH(2)O and then increased to 3 cmH(2)O a bove the baseline. Decreasing PEEP impaired compliance (P < 0.01), and oxygenation (P < 0.05), whereas increasing PEEP improved compliance ( P < 0.05) and oxygenation (P < 0.05). Neither increasing nor decreasin g PEEP caused significant changes in the carbon dioxide levels. In the second study, 24 children were studied at their baseline settings and then after increasing the PEEP by 3 cmH(2)O while simultaneously lowe ring the peak inspiratory pressure (PIP) to maintain MAP constant (12 children had lung function measurements). In the group overall increas ing PEEP while decreasing PIP resulted in an insignificant change in p (a)O(2), but a significant increase p(a)CO(2) (P < 0.01) and reduction in tidal volume (P < 0.01), the change in compliance was not signific ant. After a second period at the baseline settings, in 12 children in spiratory time (T-I) was increased while keeping MAP constant by reduc ing PIP, No significant change in p(a)O(2) or compliance was experienc ed, but p(a)CO(2) increased (P < 0.05) and tidal volume decreased (P < 0.01). In the other 12 children MAP was increased by prolonging T-I, Increasing MAP had a variable effect and the changes in p(a)O(2) and p (a)CO(2) were not significant. No critical MAP level with regard to ox ygenation was demonstrated. We conclude that in children with liver di sease, increasing PEEP can improve oxygenation and compliance, but the MAP level alone does not determine oxygenation.