Context: Thermocouples' leads are often too short, necessitating the use of an extension lead.Objective: To determine if temperature measures were influenced by extension-lead use or lead temperature changes.Design: Descriptive laboratory study. Setting: Laboratory.Other Participants: Experiment 1: 10 IT-21 thermocouples and 5 extension leads. Experiment 2: 5 IT-21 and PT-6 thermocouples.Methods: In experiment 1, temperature data were collected on 10 IT-21 thermocouples in a stable water bath with and without extension leads. In experiment 2, temperature data were collected on 5 IT-21 and PT-6 thermocouples in a stable water bath before, during, and after ice-pack application to extension leads.Results: In experiment 1, extension leads did not influence IT-21 validity (P 5 .45) or reliability (P 5 .10). In experiment 2, postapplication IT-21 temperatures were greater than preapplication and application measures (P , .05).Conclusions: Extension leads had no influence on temperature measures. Ice application to leads may increase measurement error.Key Words: uncertainty, therapeutic modalities, cryotherapy, thermotherapy Key Points N The use of extension leads did not affect thermocouple measurement reliability and validity. N Researchers should report the reliability and validity of thermocouple measurements.T hermocouples are interfaced with electrothermometers to measure temperature. Some thermocouple models, such as the implantable IT-21 (Physitemp Instruments, Inc, Clifton, NJ), have leads that are too short to reach from an electrothermometer to the tissue or substance being measured, necessitating the use of a thermocouple extension lead. When studying superficial modalities, such as ice and heat packs, researchers must place most modalities on at least part of the leads during data collection. In previous work, 1,2 we reported that an electrothermometer influenced uncertainty (validity 6 reliability), otherwise referred to as accuracy by manufacturers. 3 The only thermocouple model to influence uncertainty more than the electrothermometer manufacturer's claims was the IT-21 2 ; thermocouple manufacturers provide only range values for their equipment. 4 This finding caused us to question whether extension leads influence temperature measurement uncertainty. Because thermocouples are composed of 2 dissimilar metal wires and metal is typically a good conductor of heat energy, we also asked if altering the temperature around the thermocouple leads could influence the reported temperature. Therefore, the purpose of our study was to determine if the use of extension leads or the temperature of the thermocouple lead alters the validity and reliability of temperature measurements.
METHODS
Study DesignTwo experiments were performed. Experiment 1 was a 2 3 2 repeated-measures factorial design with extension lead (with, without) and trial (1, 2) as the independent variables. Experiment 2 was a 1 3 3 repeated-measures factorial design with phase (preapplication, ice application, postapplication) as the independent var...