Korean J Anesthesiol.  2013 Aug;65(2):121-126. 10.4097/kjae.2013.65.2.121.

The determinants of propofol induction time in anesthesia

• Adachi YU
• Satomoto M
• Higuchi H
• Watanabe K

• KMID: 2031252
• DOI: http://doi.org/10.4097/kjae.2013.65.2.121

Abstract

BACKGROUND
The required dose of anesthetics is generally smaller in patients with low cardiac output (CO). A high CO decreases the blood concentration of anesthetics during induction and maintenance of anesthesia. However, a high CO may also shorten the delivery time of anesthetics to the effect site, e.g. the brain. We assessed the time required for induction of anesthesia with propofol administered by target-controlled infusion (TCI), and investigated factors that modify the pharmacodynamics of propofol.
METHODS
After measuring CO and blood volume (BV) by dye densitometry, propofol was infused using TCI to simulate a plasma concentration of 3 microg/ml. After infusion, the time taken to achieve bispectral index (BIS) values of 80 and 60 was determined. Age, sex, lean body mass (LBM), and cardiovascular parameters were analyzed as independent variables. The dependent variables were the time taken to achieve each BIS value and the plasma concentration of propofol (Cp) 10 min after the commencement of infusion.
RESULTS
Multiple regression analysis revealed that a high CO significantly reduced the time taken to reach the first end point (P = 0.020, R2 = 0.076). Age and LBM significantly prolonged the time taken to reach the second end point (P = 0.001). Cp was negatively correlated with BV (P = 0.020, R2 = 0.073).
CONCLUSIONS
Cardiac output was a statistically significant factor for predicting the time required for induction of anesthesia in the initial phase, whereas, age and LBM were significant variables in the late phase. The pharmacodynamics of propofol was intricately altered by CO, age, and LBM.

Keyword

Cardiac output; Consciousness monitors; Pharmacokinetics; Propofol

MeSH Terms

Anesthesia
Anesthetics
Blood Volume
Brain
Cardiac Output
Cardiac Output, Low
Consciousness Monitors
Densitometry
Humans
Plasma
Propofol
Anesthetics
Propofol