Perioperative use of propofol for cardiac surgery

The influence of cardiac output on propofol and fentanyl pharmacokinetics and pharmacodynamics in patients undergoing abdominal aortic surgery

Cardiac output (CO) is expected to affect elimination and distribution of highly extracted and perfusion rate-limited drugs. This work was undertaken to quantify the effect of CO measured by the pulse pressure method on pharmacokinetics and pharmacodynamics of propofol and fentanyl administrated during total intravenous anesthesia (TIVA). The data were obtained from 22 ASA III patients undergoing abdominal aortic surgery. Propofol was administered via target-controlled infusion system (Diprifusor) and fentanyl was administered at a dose of 2-3 µg/kg each time analgesia appeared to be inadequate. Hemodynamic measurements as well as bispectral index were monitored and recorded throughout the surgery. Data analysis was performed by using a non-linear mixed-effect population modeling (NONMEM 7.4 software). Three compartment models that incorporated blood flows as parameters were used to describe propofol and fentanyl pharmacokinetics. The delay of the anesthetic effect, with respect to plasma concentrations, was described using a biophase (effect) compartment. The bispectral index was linked to the propofol and fentanyl effect site concentrations through a synergistic Emax model. An empirical linear model was used to describe CO changes observed during the surgery. Cardiac output was identified as an important predictor of propofol and fentanyl pharmacokinetics. Consequently, it affected the depth of anesthesia and the recovery time after propofol-fentanyl TIVA infusion cessation. The model predicted (not observed) CO values correlated best with measured responses. Patients' age was identified as a covariate affecting the rate of CO changes during the anesthesia leading to age-related difference in individual patient's responses to both drugs.

[Drugs for intravenous induction of anesthesia: propofol]

In a series of articles dealing with hypnotics for induction of anesthesia, this article describes the development and current value of propofol. Its significance far exceeds that of a pure induction hypnotic (sedation in diagnostic and therapeutic procedures and on the intensive care unit). Propofol is also used for sedation in diagnostic and therapeutic procedures and on the intensive care unit. In the field of induction of anesthesia, the alternatives are barely used. Some contraindications are still controversial whereas others are no longer sufficiently anchored in the users' awareness (widespread off-label use). Adverse effects, such as injection pain, infection risk and propofol-related infusion syndrome (PRIS) could be significantly reduced by pharmacovigilance. With appropriate caution nearly the whole spectrum of anesthesiology patients can be treated using propofol. The hemodynamic side effects and the rare but potentially fatal PRIS are limitations. Further developments address the water solubility and the solubilizing agents of propofol.

Fast-track cardiac anaesthesia in the elderly: effect of two different anaesthetic techniques on mental recovery

Elderly patients may be considered for 'fast-track' cardiac anaesthesia, but can suffer psychological complications and slow recovery of mental function after surgery, which can interfere with recovery. Reduced metabolism and changed distribution of anaesthetic and sedative agents can cause poor recovery. We made a prospective randomized comparison of mental function, haemodynamic stability and extubation and discharge times in elderly patients (65-79 yr) receiving two premedication, anaesthetic and sedative techniques. Patients received either propofol (n=39) (fentanyl 10-15 microg kg(-1) and propofol 2-6 mg kg(-1) intraoperatively and a propofol infusion for 3 h postoperatively) or premedication with lorazepam followed by midazolam for anaesthesia (n=39) (fentanyl 10-15 microg kg(-1) and midazolam 0.05-0.075 mg kg(-1) intraoperatively and a midazolam infusion for 3 h postoperatively). Impairment of mental function was noted in 41% of patients in the propofol group and 83% in the lorazepam and midazolam group (P=0.001) 18 h after extubation. Patients in the propofol group were extubated earlier [1.4 (SD 0.6) vs 1.9 (0.8) h, P=0.02]; and reached standard intensive care unit discharge criteria [7.6 (4.6) vs 14.2 (13) h, P=0.02] and hospital discharge criteria [4.3 (1.0) vs 4.9 (1.1) days, P=0.04) sooner than patients in the lorazepam and midazolam group, but actual discharge times did not differ between the groups. Haemodynamic values were stable in both groups.

Total intravenous anesthesia with a propofol-ketamine combination during coronary artery surgery

OBJECTIVE

To evaluate the cardiovascular effects of a propofol-ketamine combination in patients undergoing coronary artery surgery.

DESIGN

Prospective, randomized study.

SETTING

Tertiary care teaching hospital, single center.

PARTICIPANTS

Seventy-eight adult patients.

INTERVENTIONS

Patients were randomly allocated to receive propofol-ketamine for induction and maintenance of anesthesia (n = 36) or fentanyl-enflurane (controls, n = 42).

MEASUREMENTS AND MAIN RESULTS

Hemodynamics and other variables were recorded during and after surgery and for 24 hours in the intensive care unit. Before cardiopulmonary bypass (CPB), there was similar incidence of treatment for hypotension (42% of patients in both groups), tachycardia (propofol-ketamine, 6%; controls, 5%), and myocardial ischemia (propofol-ketamine, 3%; controls, 12%). In the propofol-ketamine group, there was a decreased requirement for inotropic agents after CPB (22% of patients) compared with controls (49% of patients; p = 0.02). There was a reduced incidence of myocardial infarctions (creatine kinase myocardial band >133 U/L) in the propofol-ketamine group compared with the control group (0% v 14%; p = 0.02; Fisher's exact test). Patients in the propofol-ketamine group were more likely to have their tracheas extubated within 8 hours of arrival in the intensive care unit compared with controls (33% v 7%; p = 0.01; Cochran-Mantel-Haenzel test).

CONCLUSIONS

The propofol-ketamine combination was associated with a similar incidence of pre-CPB hypotension and ischemia, a decreased need for inotropes after CPB, an earlier time to tracheal extubation, and a reduced incidence of myocardial infarctions compared with controls.

Anesthetic management of a patient with myasthenia gravis during hypothermic cardiopulmonary bypass

The anesthetic management of a patient with myasthenia gravis (MG) who underwent cardiac surgery with hypothermic cardiopulmonary bypass (CPB) is described. Using total intravenous anesthesia with propofol and a moderate dose fentanyl, the variations of neuromuscular function and serum anti-acetylcholine receptor antibody concentration were examined in relation to hypothermic CPB in the absence of muscle relaxants. The anesthetic technique used may have helped to avoid the risks incidental to muscle relaxants in this patient with MG undergoing hypothermic CPB.