Journal of Tongji Medical University = Tong ji yi ke da xue xue bao
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J. Tongji Med. Univ. · Jan 1997
Randomized Controlled Trial Clinical TrialMultiple respiratory gas monitoring causes changes of inspired oxygen concentration in closed anesthesia system.
Effect of multiple respiratory gas monitoring (MRGM) on inspired concentration of oxygen in circuit system during closed anesthesia was studied in 51 adult patients scheduled for abdominal surgery. Required flow rate of fresh oxygen (OFR), inspired oxygen concentration (FiO2) and oxygen saturation of pulse oximeter (SpO2) were measured continuously. Patients were equally divided into three groups at random, group C (no MRGN used), group M1 (using MRGM with its tail gas returned to circuit system), group M2 (using MRGM without tail gas returned). ⋯ In group M1, FiO2 decreased by 16% at 60 min and 34% at 180 min and the decrease was significantly greater than that in group C (P < 0.01). In group M2, FiO2 remained constant during closed anesthesia, which was much higher than those in group C and M1. The tail gas of Capnomac Ultima MRGM contained less oxygen than its sample gas drawn from circuit system simultaneously.