The target plasma concentration of propofol required to place laryngeal mask versus cuffed oropharyngeal airway.
To determine the target plasma concentration of propofol required to place either a laryngeal mask airway (LMA) or a cuffed oropharyngeal airway (COPA), we started a continuous target-controlled infusion of propofol in 60 ASA physical status I or II unpremedicated patients scheduled for minor orthopedic surgery with peripheral nerve block. The target plasma concentration of propofol was initially set at 2 microg/mL. When the effect-site calculated concentration of propofol was equal to the plasma concentration according to the computer simulation, the target plasma concentration was increased by 0.5-microg/mL steps until successful placement of either the LMA (n = 30) or the COPA (n = 30). The mean target plasma concentration of propofol required to place a LMA was 4.3 +/- 0.8 microg/mL compared with 3.2 +/- 0.6 microg/mL to place a COPA (P < 0.001). To successfully place the airways in 95% of patients, the target plasma concentration of propofol had to be increased up to 4 microg/mL for the COPA and 6 microg/mL for the LMA. We conclude that placing a LMA in healthy, unpremedicated patients requires target plasma concentrations of propofol higher than those required for placing a COPA.


CONCLUSIONS
We evaluated the use of target-controlled infusion of propofol to place extratracheal airways in this prospective, randomized study and demonstrated that the target plasma concentration of propofol required to successfully place a laryngeal mask in >95% of healthy, unpremedicated patients is 6 microg/mL, compared with 4 microg/mL to place a cuffed oropharyngeal airway.
Casati
A
A
Department of Anesthesiology, University of Milan, Italy. casati.andrea@hsr.it
Fanelli
G
G
Casaletti
E
E
Cedrati
V
V
Veglia
F
F
Torri
G
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D018686:Anesthetics, Intravenous / Q000097:blood*; D006801:Humans; D017214:Laryngeal Masks / Q000009:adverse effects / Q000592:standards*; D008875:Middle Aged; D009960:Oropharynx / Q000502:physiology*; D015742:Propofol / Q000097:blood*; D011446:Prospective Studies; D013223:Statistics as Topic
D018686:Anesthetics, Intravenous; D015742:Propofol