This is a prospective study looking at ways to measure the cuff pressure of cuffed endotracheal tubes (ETTs). We will be comparing a hand-held manometer (MM) to the transducer of an invasive pressure monitoring setup (IPMS), which is commonly used for arterial or central venous pressure monitoring. The investigators previously did this study in vivo with ETTs in polyvinyl chloride (PVC) "tracheas" and we found that there is good correlation between the pressure readings using the MM and the IPMS. The purpose of the current study is to validate the in vitro findings in clinical situations.