This part of ISO 11990 specifies a method of testing the continuous wave (cw) resistance of the shaft of a tracheal tube designed to resist ignition by a laser. It is not applicable to other components of the system, such as the inflation system and cuff, which are defined in ISO 11990-2 (see Note 1). NOTE 1 ISO 11990-2 specifies the method for testing the laser resistance of the tracheal tube cuff. This part of ISO 11990 can be used to measure and describe the properties of materials, products or assemblies in response to heat and flame under controlled laboratory conditions. It does not describe or appraise the fire hazard or fire risk of materials, products, or assemblies under actual clinical use conditions. However, the results of this test can be used as one element of a fire risk assessment which takes into account all factors pertinent to an assessment of the hazard of a particular end use. NOTE 2 The direct applicability of the result of this test method to the clinical situation has not been fully established. CAUTION - This test method can involve hazardous materials, operations, and equipment. This part of ISO 11990 provides advice on minimizing some of the risks associated with its use but does not purport to address all such risks. It is the responsibility of the user of this part of ISO 11990 to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.