Multipatient Anesthetic Mass Spectrometry

Open Access
Publisher Website
Google Scholar
Abstract
A centrally located mass spectrometer sequentially sampled airway gases from 10 anesthetized patients through 30 m long, 1.07 mm, ID [internal diameter], nylon catheters and 3 way solenoid valves. End-tidal and inspired concentrations of O2, N2, CO2, N2O and halothane, enflurane or isoflurane were displayed on a computer terminal screen in each OR [operating room] with trend plots. While a gas sample from 1 room was analyzed, all other catheters were slowly sampled in order to continuously store 20 s concentration profiles ready for analysis. The stored gas sample was analyzed at twice the rate it was sampled. The computer switches catheters after 1 breath was validated from 2 comparable end-tidal P[partial pressure]CO2 values. Large flow changes produced by switching from one catheter to the next required regulation of the pump pressure in the mass spectrometer. This method reduced the time required to sample each room to 6.96 s (4-10 rooms). Catheter transit slowed the response to a step increase of concentration by .apprx. 0.13 s (from 10-90%) and prolonged the transit time through the catheter for a volatile anesthetic by about 0.04 s more than N2. The monitoring facility was used in each room for an average of 5.5 h/day. Two years of experience suggested that it could facilitate detection of faulty technique and equipment, reduce cost of anesthetic agents by encouraging use of closed systems, increase patient safety, aid research and teaching, and diminish exposure of OR personnel to anesthetics. Inherent problems resulted in an inoperative time of < 2%.

This publication has 0 references indexed in Scilit: