Small tubes revisited.

We measured the peak inflation and end expiratory pressure at the proximal and distal ends of two sizes of tracheal tube in men and women receiving positive pressure ventilation. There was a statistically significant increase in proximal inflation pressure when the smaller size of tube (6.5 mm for men, 6.0 mm for women) was used. There was no increase in distal inflation or end expiratory pressures. Clinically satisfactory positive pressure ventilation was obtained when 6.0 and 6.5 mm tracheal tubes were used. The advantages and disadvantages of using small sizes of tracheal tube are discussed.