Predicted Propofol Effect-Site Concentration for Induction and Emergence of Anesthesia During Early Pregnancy

Abstract

Propofol dose and predicted propofol effect-site concentration at LOC are decreased during early pregnancy. Progesterone does not explain this result.

Influence of a modified propofol equilibration rate constant (ke0) on the effect‐site concentration at loss and recovery of consciousness with the Marsh model

“…In a previous study using the Diprifusor (with its lower k e0 ), individual effect‐site concentration values of propofol at loss and recovery of consciousness were similar among healthy adult volunteers, and it was suggested that the effect‐site concentration of propofol at loss of consciousness could be used as a guide to predict when consciousness would be recovered and the patient would wake up . However, in another study using the Base Primea (with its higher k e0 ), pregnant women woke up at lower effect‐site concentration values than that at loss of consciousness . Theoretically, the real effect‐site concentration of propofol would be similar at loss and recovery of consciousness in the same patient.…”

“…Theoretically, the real effect‐site concentration of propofol would be similar at loss and recovery of consciousness in the same patient. However, clinically, there are wide variations in the estimated effect‐site concentration depending on the selected pharmacokinetic models . Thus, when using the modified Marsh model with higher k e0 , recovery of consciousness should not be predicted based on the effect‐site concentration value, which has been estimated at loss of consciousness.…”

“…An investigator blinded to group allocation checked for loss of consciousness every 10 s after the propofol infusion was started. Loss of consciousness was defined a lack of response to the request ‘open your eyes’, said in a normal tone of voice and without touching the patient . After loss of consciousness, a ProSeal™ laryngeal mask airway (Laryngeal Mask Company, San Diego, CA, USA) was inserted and mechanical ventilation of the lungs with 60% nitrous oxide and 40% oxygen was started.…”

“…Several previous studies have investigated the effect‐site concentration of propofol leading to loss of consciousness in healthy volunteers or surgical patients , but this has varied markedly, between 2.0 and 5.0 μg.ml −1 . Moreover, the correlation between the effect‐site concentration of propofol at loss of consciousness and when waking up was also inconsistent, depending on the TCI device used . As the effect‐site concentration of a drug is an expression of its pharmacological effect, it may differ according to the clinical circumstances.…”

The effect of progesterone on the anesthetic and analgesic requirements for ovariohysterectomy in the dog

“…Chinese researchers studied groups of women receiving anesthesia for termination of early pregnancy, and found decreased MAC for isoflurane, halothane and enflurane compared with non-pregnant women (Chan et al 1996;Gin and Chan 1994). Consequent studies found decreased thiopentone requirements for hypnosis and anesthesia and decreased propofol requirements for loss of consciousness in the same setting (Gin et al 1997;Mongardon et al 2009), and the first study to prove a correlation between the decreased sevoflurane MAC and high progesterone concentration was published in 2006 (Erden et al 2005). Such correlations were shown again in women receiving anesthesia in 2014.…”