An evaluation of the performance of minimal resistance non-rebreathing systems

Minimal resistance to spontaneous respiration has been proposed as a safe method for reducing operative bleeding. The Magill, Bullough, and Gilston T-piece non-rebreathing systems have been tested for resistance in steady-state conditions of pressure gradient and gas flow. The slope of the lines on the graph of the pressure gradient within an endotracheal tube against the squared value of the simulated expiratory flow rate illustrated the low resistance characteristics of the Gilston T-piece compared with the Magill and Bullough systems. In a within-patient trial, the resistance characteristics of the Gilston T-piece and Magill systems were confirmed by measuring the patterns of airway flow and endotracheal pressure changes with rapidly responding transducers. In conclusion, the Gilston T-piece system offers the least resistance to respiration of those tested, and provides the greatest opportunity for assessment of reduced operative bleeding in a clinical trial.