BACKGROUND: We evaluated the factors affecting the need for cuff deflation to maintain intracuff pressure (P_cuff) below 22 mmHg in two types of wire-reinforced endotracheal tubes; type A: Safety-Flex^TM (Mallinckrodt, Athlone, Ireland) and type B: Insung(R) (Insung, Seoul, Korea).

METHODS: Eighty patients were randomly divided into four groups (n = 20 for each); Group F-A: female, type A; Group F-B: female, type B; Group M-A: male, type A; Group M-B: male, type B. Sealing volume and sealing pressure (SP) were measured. Whenever Pcuff reached 22 mmHg during N₂O administration, the cuff was deflated to SP. Elapsed time to first deflation (1-CP₂₂) and deflation frequencies were recorded.

RESULTS: Specific cuff compliance (C_cuff) was higher in type A than that in type B (P < 0.05). More patients in Group F-B and M-B needed deflation than those in Group F-A and M-A, respectively (P < 0.05). 1-CP₂₂ in patients intubated with type B was shorter than with type A (P < 0.05). In both tubes type A and B, SP was higher in patients who needed deflation compared to ones that did not (P < 0.05).

CONCLUSIONS: Use of wire-reinforced tubes with high C_cuff decreases the frequency of deflation. Low SP also reduces the need for cuff deflation to keep the P_cuff below 22 mmHg during N₂O anesthesia.