OBJECTIVE: To compare minimum fresh gas flow (V(min)) requirements and respiratory resistance in the Uniflow and Bain anaesthetic breathing systems used in the Mapleson D mode. Animals Seven @entity1707 , aged 8-12 weeks, anaesthetized for ophthalmic surgery. MATERIALS AND METHODS: Anaesthesia was maintained with @entity1508 delivered in @entity26 using a (Mapleson D) Bain breathing system. The V(min) that prevented re-breathing was found, and peak inspiratory (PIP) and peak expiratory ( @entity7955 ) pressures measured. The fresh gas flow (V(f)) was then increased to V(min) + 50%, then V(min) + 100%, and respiratory pressures re-measured. A heat and moisture exchanger (HME) was inserted at the endotracheal tube and the procedure repeated. The breathing system was then exchanged for a Uniflow and the protocol repeated. After final disconnection from the breathing system, the animals' peak inspiratory and expiratory flows, tidal, and minute volumes (Vm) were measured over five respiratory cycles. RESULTS: The V(min) (L minute(-1); mL kg(-1) minute(-1)) required to prevent rebreathing in the Uniflow system [8.1(mean) +/-1.7 (SD); 332 +/- 94] was significantly greater than the Bain system (6.5 +/- 1.1; 256 +/- 64). At V(min), @entity7955 with the Uniflow (3.5 +/- 0.1 cm @entity2507 ) was significantly higher than the Bain system (2 +/- 0.7 cm @entity2507 ), but PIP values did not differ (Uniflow -0.6 +/- 2.1 cm @entity2507 ; Bain system -0.2 +/- 0.6 cm @entity2507 ). With both systems, @entity7955 increased significantly (p < 0.001) with each increase in V(f): Uniflow system 4.2 +/- 0.4 (V(min) + 50%) and 5.5 +/- 0.5 cm @entity2507 (V(min) + 100%); Bain system 2.8 +/- 0.7 (V(min) + 50%) and 3.5 +/- 0.7 cm @entity2507 (V(min) + 100%). Insertion of the HME did not alter pressures. The mean tidal volume was 6.4 +/- 1.6 mL kg(-1); mean Vm was 184.9 +/- 69.8 mL kg(-1) and mean respiratory rate was 28 +/- 5 breaths minute(-1). In one @entity1707 breathing with the Uniflow system @entity7955 rose sharply; respiratory and heart rates increased, and @entity943 occurred. When the system was changed and V(f) reduced, physiological variables became normal. CONCLUSION: The study discredited the hypothesis that the two breathing systems behave similarly. Values for V(min) and @entity7955 were higher with the Uniflow system. Increasing V(f) increased @entity7955 with both systems. Insertion of an HME did not affect respiratory pressures. CLINICAL RELEVANCE: The Uniflow used in Mapleson D mode is not suitable for anaesthesia in young spontaneously breathing @entity1707 .

Comparison of the Bain system and Uniflow universal anaesthetic breathing systems in spontaneously breathing young XXXX .

@entity1707 :: ('9823', 'Species') :: ['pigs', 'pig'] @entity7955 :: ('MESH:C073248', 'Chemical') :: ['PEP'] @entity1508 :: ('MESH:D006221', 'Chemical') :: ['halothane'] @entity26 :: ('MESH:D010100', 'Chemical') :: ['oxygen'] @entity2507 :: ('CHEBI:33813', 'Chemical') :: ['H(2)O'] @entity943 :: ('MESH:D001145', 'Disease') :: ['ventricular dysrhythmias']
@entity1707 :: (9823,Species) :: ['pigs']
