Comparison of circle absorber and Jackson-Rees systems for paediatric anaesthesia.

To evaluate effects of anaesthesia delivery systems on respiratory work in infants, we measured end-tidal PCO2 (PETCO2), transcutaneous PCO2 (PTcCO2) respiratory rate and arterial blood gases in infants (ages 0.2 to 23.8 months) anaesthetised with either a Jackson-Rees (n = 11) or paediatric circle absorber system (n = 15). Two hours after induction, with assisted ventilation there was no difference in PETCO2, PTcCO2, respiratory rate, pH or PaCO2 in infants anaesthetised with either system. In the laboratory, we measured inspiratory and expiratory resistances to breathing through each system at various tidal volumes and total gas flows into the circuit. These values were compared to resistances created by breathing through an appropriately sized endotracheal tube. Although there was lower resistance to ventilation through Jackson-Rees system, both systems had lower resistances for almost all flows tested than breathing through an endotracheal tube alone (p less than 0.05). The paediatric circle absorber system is an efficient apparatus for anaesthetising spontaneously breathing infants.