A lower solubility recommends the use of desflurane more than isoflurane, halothane, and enflurane under low-flow conditions.
OBJECTIVE
To determine whether the lower solubility of desflurane, over that of isoflurane, enflurane, and halothane, favors its use in low-flow anesthesia.


METHODS
Prospective clinical study.


METHODS
Technical University of Munich.


METHODS
40 elderly (> or = 65 yrs), ASA physical status II and III surgical patients.


METHODS
All patients were anesthetized and received delivered concentrations (FD) of 4% desflurane, 1.5% isoflurane, 1.8% enflurane, or 0.9% halothane (n = 10 patients for each anesthetic) in a fresh gas inflow of 3 L/min (high-flow), until end-tidal target concentrations (FA) of 2% desflurane, 0.5% isoflurane, 0.6% enflurane, and 0.3% halothane were obtained. After 30 minutes, the inflow was decreased to 1 L/min (low-flow), and the FD and the inspired concentration (FI) were adjusted to maintain the target concentration.


RESULTS
The concentrations of the halogenated anesthetics, as well as nitrous oxide, oxygen (O2), and carbon dioxide, were measured in delivered gas at the common gas outlet and at the endotracheal tube connector. Transcutaneous O2 saturation, noninvasive blood pressure, and heart rate were also measured. During the first 30 minutes of high-flow administration, the target concentration was attained sooner with desflurane than with isoflurane, enflurane, or halothane (median levels: 4 min vs. 6 min, 8 min, or 10 min; p < 0.01). After the reduction of inflow to 1 L/min, FD had to be materially increased to maintain F1 and FA for the more soluble anesthetics, but not for desflurane.


CONCLUSIONS
At low flows, FD provides a reasonable surrogate of F1 and FA for desflurane, but not for isoflurane, enflurane, or halothane. The rapid and predictable titrability of desflurane favors its safe use in low-flow technique.
Hargasser
S
S
Hipp
R
R
Breinbauer
B
B
Mielke
L
L
Entholzner
E
E
Rust
M
M
D000368:Aged; D000769:Anesthesia, Inhalation / Q000379:methods*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000032:analysis / Q000737:chemistry*; D002245:Carbon Dioxide / Q000032:analysis; D000077335:Desflurane; D004737:Enflurane / Q000008:administration & dosage / Q000032:analysis / Q000737:chemistry*; D005260:Female; D006221:Halothane / Q000008:administration & dosage / Q000032:analysis / Q000737:chemistry*; D006801:Humans; D007530:Isoflurane / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry*; D008297:Male; D009609:Nitrous Oxide / Q000032:analysis; D010100:Oxygen / Q000032:analysis; D011446:Prospective Studies; D012212:Rheology; D012995:Solubility; D013990:Tidal Volume; D013997:Time Factors
D018685:Anesthetics, Inhalation; D002245:Carbon Dioxide; D004737:Enflurane; D000077335:Desflurane; D007530:Isoflurane; D009609:Nitrous Oxide; D010100:Oxygen; D006221:Halothane