Increasing evidence of the benefits of noninvasive ventilatory support in a variety of pulmonary disorders has led to the relatively widespread use of bi-level positive pressure support and noninvasive nasal positive pressure ventilation (NPPV). Assessment of PaC02 is essential for evaluation of the adequacy of alveolar ventilation in this setting. PaC02 can be measured on samples obtained by arterial puncture or from an indwelling catheter in the radial artery. Repeated sampling of arterial blood remains so far the “gold standard” for estimating the adequacy of ventilatory support. However, arterial catheterization needs costly equipment, specially trained personnel, and in most cases the environment of an ICU. There is also a low but measurable morbidity associated with arterial catheterization. cialis professional 20 mg
Noninvasive assessment of PaC02 can be performed by measuring transcutaneous C02 (TcPco2) or peak expired C02. The latter, however, is a poor predictor of PaC02. Also, accurate measurement of peak expired C02 cannot be achieved during nasal continuous positive airway pressure ventilation because of continuous flow through the mask. Transcutaneous measurement of carbon dioxide theoretically appears more appropriate for monitoring PaC02. This measurement is based on the observation that C02 has a high tissue solubility and diffuses through the skin. It can be performed by two different types of sensors: the Severinghaus electrode and the Hewlett-Packard TcPco2 device (Waltham, Mass), which uses an infrared transcutaneous capnometer. Most capnometers use the Severinghaus electrode.
Available data as to the precision of TePco2 have given conflicting results.-” Therefore, the present study was designed to evaluate a new device for the measurement of TcPco2. We wanted to test for agreement with arterial values, detect any possible drift of TcPco2 over time, and describe the response of TcPco2 when initiating or interrupting NPPV in hypercapnic patients.
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