| 摘要 |
An inner cannula 20 for a tracheostomy tube 1 has two regions 30, 31 of circumferential corrugations 126 extending along only the outside of the cannula. The two corrugated regions 30 and 31 are separated by two uncorrugated regions 32 and 33. Towards the patient end 120 of the cannula 20 the peripheral extent of the corrugations 30, 31 gradually increases and the extent of the uncorrugated regions 32, 33 decreases, so that the patient end 121 is more flexible than the machine end 120. |
