Pharmacokinetic model-driven infusion of sufentanil and midazolam during cardiac surgery: assessment of the prospective predictive accuracy and the quality of anesthesia

Population pharmacokinetic modeling of sufentanil in adult Korean patients undergoing cardiopulmonary bypass surgery

Sufentanil is frequently used as an anesthetic agent in cardiac surgery owing to its cardiovascular safety and favorable pharmacokinetics. However, the pharmacokinetics profiles of sufentanil in patients undergoing cardiopulmonary bypass (CPB) surgery remain less understood, which is crucial for achieving the desired level of anesthesia and mitigating surgical complications. Therefore, this study aimed to develop a population pharmacokinetic model of sufentanil in patients undergoing CPB surgery and elucidate the clinical factors affecting its pharmacokinetic profile. Adult patients who underwent cardiac surgery with CPB and were administered sufentanil for anesthesia were enrolled. Arterial blood samples were collected to quantify plasma concentrations of sufentanil and clinical laboratory parameters, including inflammatory cytokines. A population pharmacokinetic model was established using nonlinear mixed-effects modeling. Simulations were performed using the pharmacokinetic parameters of the final model. Overall, 20 patients were included in the final analysis. Sufentanil pharmacokinetics were modeled using a two-compartment model, accounting for CPB effects. Sufentanil clearance increased 2.80-fold during CPB and warming phases, while the central compartment volume increased 2.74-fold during CPB. CPB was a significant covariate affecting drug clearance and distribution volume. No other significant covariates were identified despite increased levels of the inflammatory cytokines, including IL-6, IL-8, and TNF-α during CPB. The simulation indicated a 30 μg loading dose and 40 μg/h maintenance infusion for target-controlled infusion. Additionally, a bolus dose of 60 μg was added at CPB initiation to adjust for exposure changes during this phase. Considering the target sufentanil concentrations, a uniform dosing regimen was acceptable for effective analgesia.

Performance of the Minto model for the target-controlled infusion of remifentanil during cardiopulmonary bypass

We studied the predictive performance of the Minto pharmacokinetic model during cardiopulmonary bypass in patients undergoing cardiac surgery. Patients received remifentanil target-controlled infusion using the Minto model during total intravenous anaesthesia with propofol. From 56 patients, 275 arterial blood samples were drawn before, during and after bypass to determine the plasma concentration of remifentanil, and the predicted concentrations were recorded at each time. For pooled data, the median prediction error and median absolute prediction error were 21.3% and 21.8%, respectively, and 22.1% and 22.3% during bypass. Both were 148.4% during hypothermic circulatory arrest and measured concentrations were more than three times greater than predicted (26.9 (17.0) vs. 7.1 (1.6) ng.ml^-1 ). The Minto model showed considerable bias but overall acceptable precision during bypass. The target concentration of remifentanil should be reduced when using the Minto model during hypothermic circulatory arrest.

Sufentanil postconditioning protects the myocardium from ischemia-reperfusion via PI3K/Akt-GSK-3β pathway

BACKGROUND

Previous studies have shown that opioid postconditioning reduces apoptosis through antiapoptotic signaling. The present study evaluated whether sufentanil could induce cardioprotection after ischemia-reperfusion (I/R) and whether the PI3K/Akt-GSK-3β pathway modulates antiapoptotic proteins in sufentanil postconditioning.

METHODS

We subjected male Sprague-Dawley rats to 30 min of myocardial ischemia and 2 h of reperfusion. We randomized rats into seven groups: sham, I/R, sufentanil postconditioning (I/R+sufen), sham plus sufentanil (sham+sufen), sham plus 15 μg · kg(-1) intravenous wortmannin (PI3K inhibitor), I/R plus wortmannin, and sufentanil plus wortmannin. We induced sufentanil postconditioning with 3 μg · kg(-1) sufentanil for 3 min in the beginning of reperfusion after 30 min ischemia. We assessed hemodynamics, myocardial infarct size, number of apoptotic cardiomyocytes, total Akt and GSK-3β, phosphorylated Akt and GSK-3β, caspase-3, Bax, and Bcl-2 protein expression.

RESULTS

The I/R+sufen group had significantly reduced infarct size compared with the I/R group (23.3% ± 9.0% versus 50.1% ± 7.4%; P < 0.05). The apoptotic index of cardiomyocytes was significantly reduced with sufentanil treatment (20.0% ± 3.5%) compared with the I/R group (47.0% ± 6.3%; P < 0.05). The I/R+sufen group reduced the expression of protein-cleaved caspase-3 and Bax, and increased Bcl-2, phosphorylated Akt, and GSK3β compared with the I/R group. Wortmannin eliminated the cardioprotection produced with sufentanil treatment.

CONCLUSIONS

Sufentanil postconditioning can induce myocardial protection by activating the PI3K/Akt-GSK-3β pathway and modulating Bax and Bcl-2 expression.

Predictive performance of the Domino, Hijazi, and Clements models during low-dose target-controlled ketamine infusions in healthy volunteers

BACKGROUND

Healthy volunteers received low-dose target-controlled infusions (TCI) of ketamine controlled by the Domino model while cognitive function tests and functional neuroimaging were performed. The aim of the current study was to assess the predictive performance of the Domino model during these studies, and compare it with that of three other ketamine models.

METHODS

Fifty-eight volunteers received ketamine administered by a TCI device on one or more occasions at target concentrations of either 50, 100, or 200 ng ml-1. At each target concentration, two or three venous blood samples were withdrawn during infusion, with a further sample after the infusion ended. Ketamine assays were performed by gas chromatography. The plasma concentration time courses predicted by the Hijazi, Clements 125, and Clements 250 models were calculated retrospectively, and the predictive performance of each of the models was assessed using Varvel methodology.

RESULTS

For the Domino model, bias, inaccuracy, wobble, and divergence were - 2.7%, 33.9%, 24.2%, and 0.1463% h-1, respectively. There was a systematic increase in performance error over time. The Clements 250 model performed best by all criteria, whereas the Hijazi model performed least well by all criteria except for bias.

CONCLUSIONS

Performance of the Domino model during control of low-dose ketamine infusions was sub-optimal. The Clements 250 model may be a better model for controlling low-dose TCI ketamine administration.

Midazolam suppresses thrombin-induced heat shock protein 27 phosphorylation through inhibition of p38 mitogen-activated protein kinase in cardiac myocytes

It has been shown that anesthetics have effects of cardiac preconditioning. Heat shock proteins (HSPs) function as molecular chaperone. Among them, HSP27, a low-molecular-weight HSP, abundantly exist in heart. However, the relationship between anesthetics and HSP27 in heart is not yet clarified. We investigated whether thrombin induces or phosphorylates HSP27 in primary cultured mouse myocytes and the effect of midazolam on the thrombin-stimulated HSP27 phosphorylation and the mechanism behind it. Thrombin time dependently phosphorylated HSP27 at Ser-15 and Ser-85 while having no effect on the levels of HSP27. Midazolam markedly suppressed the thrombin-induced phosphorylation of HSP27 at both Ser-15 and Ser-85. Thrombin induced the phosphorylation of p44/p42 MAP kinase and p38 MAP kinase without affecting stress-activated protein kinase/c-Jun N-terminal kinase. In addition, midazolam attenuated the phosphorylation of thrombin-induced p38 MAP kinase but not that of p44/p42 MAP kinase. SB203580 and PD169316, inhibitors of p38 MAP kinase, suppressed the thrombin-induced phosphorylation of HSP27 at both Ser-15 and Ser-85. These results strongly suggest that thrombin induces the HSP27 phosphorylation at least through the p38 MAP kinase activation in cardiac myocytes and that midazolam inhibits the thrombin-induced HSP27 phosphorylation via suppression of p38 MAP kinase activation.