How do I sterilize long hollow tubes? Does a guideline, standard or literature exist that tells us whether we can steam sterilize a hollow needle (e.g. inside diameter 0.8 mm, length 350 mm). Is the material of the tube relevant to the relation of diameter/length?

Philip de Vries

Dear Philip,

Working group 5 of CEN TC102 has defined the term "hollow" in their draft standard for small steam sterilizers. PrEN 13060-2 gives the following definition for Hollow space A: Single ended open space where the ratio of length of cavity to diameter is greater than or equal to 1 and less than or equal to 750 and where the length of cavity is not greater than 1500 mm and double ended open space where the ratio of length of cavity to diameter is greater than or equal to 2 and less than or equal to 1500 and where the length of the cavity is not greater than 3 000 mm.

The ratio of length of cavity to diameter for the instrument you describe is 438. This means that it is well within the range given by CEN TC102 wg5 for a double ended open space.

Working group 7 of CEN TC102 (chemical indicator group) has written a standard for a test device capable of verifying whether a (small) steam sterilizer is capable of sterilizing hollow instruments as defined in prEN 13060-2. If a sterilizer fulfils the requirements in prEN 13060-1 and prEN 13060-2 and it is capable of sterilizing the test device given in prEN 867-5, one may assume that the sterilizer is capable of sterilizing all hollow instruments that fall under the definition. It is noted that non of the draft standards mentioned here make any limitations to the materials from which hollow medical devices are fabricated, indicating that the material has no apparent influence on the air removal or steam penetration.

The above mentioned draft standards all deal with small steam sterilizers and test devices for small steam sterilizers. However, I see no reason why the principles should not be translated for application in large steam sterilizers.

The answer to your question: When your steam steriliser fulfils the requirements of EN 285 and EN 554 and is capable of sterilizing the test device for hollow loads as given in prEN 867-5, it will be capable of sterilising the hollow needle you described in your question. (Please notice that the Bowie & Dick test is a model for porous loads. The air removal steam penetration dynamics in porous loads bear little resemblance to those in hollow instruments. In other words the result of the Bowie & Dick test has little relevance towards the sterilisation of hollow instruments. In my view a positive Bowie & Dick test is not acceptable proof that the steam sterilizer is capable of sterilizing hollow medical devices.)

Adrie de Bruijn

Dear Mr. Philip
my name is Cheery YAN. one day, i have heard of a phrase "pren-13060. so i want to look for some detail information about PrEN-13060.
i am just a student, and my intrests make me write this letter. can you reply me? and send me some information about it?
i am looking forward for you!
thank you very much!
PS. maybe i just made a rough decision, if it is, please excuse me!
yours sincerely