1. What are the requirements of the ISO 9360 standard "Anaesthetic and Respiratory Equipment - Heat and Moisture Exchangers for Use in Humidifying Respired Gases in Humans"? The ISO 9360 standard is a voluntary standard which provides guidance to the manufacturers of Heat and Moisture Exchangers on a variety of subjects. For example, it discusses packaging and labeling of the products. It also suggests product connectors to be 15mm I.D. on one end, with an additional 22mm O.D. if desired, and 15mm O.D. on the other end. Most frequently, what is referred to as the ISO 9360 standard is actually section 6 of that standard, "Test Methods". By adhering to a universal method of testing, it will become a lot easier for a clinician to look at two different products objectively, as they are all subjected to precisely the same test method. Test conditions are established for different size HMEs and the test rig is completely defined in the standard. The testing of each product has to be performed over a complete 24 hour time period. Depending on the size of the test unit, it has to be tested at particular tidal volumes and breath frequencies. For the average adult HME, the tidal volumes are 250 ml, 500 ml and 1,000 ml and tests are performed at 20 breath/ minute. A precise level of moisture is added into the test rig at a precise temperature setting (34ºC and 37.6mg H2O/ liter of inspired air) and is maintained during the 24 hours. Since the input is identical for all products tested, the difference in output describes the performance of the particular test product. In addition to moisture return, pressure drop is also measured at various flow rates and should be published in the protocol.