[The arterial blood gas change in anesthetized patients with apnea: disadvantage of hyperventilation before intubation].
We studied the arterial blood gas changes during 4 minute apnea period without using constant oxygen flow under anesthesia. Fifteen adult surgical patients (ASA PS 1 or 2, 21-49 years of age) were randomly divided into 3 groups by ETCO2 before the start of apnea (group I: 40 mmHg, group II: 30 mmHg, group III: 20 mmHg). In addition, each patient was monitored with pulse oximetry, ECG, blood pressure, FIO2 and ETCO2. The rate of rise of PaCO2 during the apnea showed no significant difference among these 3 groups. In the first minute of apnea, PaCO2 increased 9.8 +/- 1.9 mmHg, and then increased at a rate of 3.4-4.4 mmHg.min-1 thereafter. In conclusion, the rate of rise of PaCO2 in anesthetized patients with apnea was logarithmic and there was no correlation with pre-apnea ETCO2. The rate of SpO2 decrease was significant in hyperventilated group (III). Thus, hyperventilation applied before the endotracheal intubation is not of benefit to the oxygenation of healthy humans.
Kobayashi
T
T
Department of Anesthesiology, Daiichi Hospital, Nippon Medical School, Tokyo.
Yokoyama
K
K
D000328:Adult; D000768:Anesthesia, General; D001049:Apnea / Q000097:blood*; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D012121:Respiration, Artificial / Q000009:adverse effects*
D002245:Carbon Dioxide; D010100:Oxygen