A clinical catheter for continuous blood gas measurement by mass spectrometry.

A new Teflon catheter for continuous in vivo measurement of blood gases by mass spectrometry has an outer diameter of 0.032 in. and can be inserted through percutaneous puncture with an 18-gauge needle. Response time (63% of a total change) is 40 s for oxygen and 65 s for carbon dioxide. When calibrated in analyzed gas at 37 degrees C, the catheter-mass spectrometer system has been shown to analyze tonometered blood with an error of 1.6% for oxygen and 1.9% for carbon dioxide. Temperature dependence is 2.0% per degrees C for oxygen and 1.6% per degrees C for carbon dioxide. The catheter was thrombo-resistant during in vivo use in seven dogs and measurements compared favorably with results of blood sample analyses by standard hospital methods. Compared with previous devices, the new catheter provides size and convenience, advantages that make it more applicable for routine clinical use.