Journal of clinical monitoring
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Flow through an endotracheal tube (ETT) causes a pressure loss across the tube. This loss results in a difference between pressure measured at the airway and pressure measured in the trachea. This difference can lead to errors when calculating pulmonary mechanics and when setting ventilators. We have tested a method of estimating tracheal pressure from the pressure in the ETT cuff. ⋯ The cuff estimation technique gives real-time, continuous, noninvasive tracheal pressure measurements in intubated animals with cuffed ETTs.
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Comparative Study
A new system to record reliable pulse oximetry data from the Nellcor N-200 and its applications in studies of variability in infant oxygenation.
We have developed a simple system for internal validation of oximetry data collected over many hours from the Nellcor N-200 pulse oximeter (Nellcor, Inc., Hayward, CA). This system uses signals from the oximeter alone and a validation algorithm that is based in a computer connected to the oximeter. Unlike other validation systems, this system does not require connections to other monitors. ⋯ While variability in infant SpO2 is a well-known phenomenon, the amount seen here was unexpected. For example, the range of true saturations frequently recorded was quite wide at a reported mean SpO2 of 90% (from 81 to 94%; but, the range was only from 92 to 98% at a mean SpO2 of 96%). These findings demonstrate the usefulness of the new system and, if substantiated in more detailed studies, have important implications for the use of pulse oximeters to assess oxygenation in newborns.