Propofol Inhibits Human Platelet Aggregation Induced by Proinflammatory Lipid Mediators

The comparison of the effects of ketamine and etomidate on cardiodynamics, biochemical and oxidative stress parameters in Wistar male rats

It is well known the use of ketamine and etomidate in clinical practice; however, the difference in the systemic effects of these two anesthetic agents is still debatable. Thus, in the present study we aimed to compare their effects on heart, and other organs through estimation of cardiodynamics, biochemical and hematological parameters. Male Wistar rats were divided in 2 groups containing of 2 subgroups (n = 7 in each subgroup, n = 28 in total): (1) bolus injection of anesthetic ketamine (40 mg/kg b.w., i.p. n = 14); (2) bolus injection of anesthetic etomidate (20 mg/kg b.w., i.p. n = 14). The experiments were done in vitro in one subgroup of each group: cardiodynamic variables (dp/dt_max, dp/dt_min, heart rate), coronary flow, oxidative stress in coronary effluent and cardiac tissue homogenate, and in vivo in another subgroup: biochemical and hematological parameters, and oxidative stress in haemolysate. Significantly increased left ventricular contractility (dp/dt_max) and relaxation (dp/dt_min) were noticed in etomidate group. Creatinine (CREA), HDL cholesterol and folate were significantly higher in etomidate group, whereas amylase (AMY) and eosinophils in ketamine group. Our results suggested that ketamine has more antioxidant potential compared to etomidate, and etomidate has more favorable effects regarding cardiac performance.

A Drug Repurposing Method Based on Drug-Drug Interaction Networks and Using Energy Model Layouts

Complex network representations of reported drug-drug interactions foster computational strategies that can infer pharmacological functions which, in turn, create incentives for drug repositioning. Here, we use Gephi (a platform for complex network visualization and analysis) to represent a drug-drug interaction network with drug interaction information from DrugBank 4.1. Both modularity class- and force-directed layout ForceAtlas2 are employed to generate drug clusters which correspond to nine specific drug properties. Most drugs comply with their cluster's dominant property; however, some of them seem not to be in a proper position (i.e., in accordance with their already known functions). Such cases, along with cases of drugs that are topologically placed in the overlapping or bordering zones between clusters, may indicate previously unaccounted pharmacologic functions, thus leading to potential repositionings. Out of the 1141 drugs with relevant information on their interactions in DrugBank 4.1, we confirm the predicted properties for 85% of the drugs. The high prediction rate of our methodology suggests that, at least for some of the 15% drugs that seem to be inconsistent with the predicted property, we can get very good repositioning hints. As such, we present illustrative examples of recovered well-known repositionings, as well as recently confirmed pharmacological properties.

Influence of propofol on isolated neonatal rat carotid body glomus cell response to hypoxia and hypercapnia

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The intravenous anaesthetic propofol acts directly on carotid body glomus cells to inhibit their response to hypoxia.

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Propofol acts via novel mechanisms, as we excluded action via its known target receptors (nicotinic, GABA-ergic, or K+ channel).

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Inhibition of the hypoxic response is clinically relevant in anaesthesia.

In humans the intravenous anaesthetic propofol depresses ventilatory responses to hypoxia and CO₂. Animal studies suggest that this may in part be due to inhibition of synaptic transmission between chemoreceptor glomus cells of the carotid body and the afferent carotid sinus nerve. It is however unknown if propofol can also act directly on the glomus cell. Here we report that propofol can indeed inhibit intracellular Ca²⁺ responses to hypoxia and hypercapnia in isolated rat glomus cells. Neither this propofol effect, nor the glomus cell response to hypoxia in the absence of propofol, were influenced by GABA receptor activation (using GABA, muscimol and baclofen) or inhibition (using bicuculline and 5-aminovaleric acid). Suggesting that these effects of propofol are not mediated through GABA receptors. Propofol inhibited calcium responses to nicotine in glomus cells but the nicotinic antagonists vecuronium and methyllycaconitine did not inhibit calcium responses to hypoxia. TASK channel activity was not altered by propofol. The glomus cell Ca²⁺ response to depolarisation with 30 mM K⁺ was however modestly inhibited by propofol. In summary we conclude that propofol does have a direct effect upon hypoxia signalling in isolated type-1 cells and that this may be partially due to its ability to inhibit voltage gated Ca²⁺_v channels. We also note that propofol has the capacity to supress glomus cell excitation via nicotinic receptors and may therefore also interfere with paracrine/autocrine cholinergic signalling in the intact organ. The effects of propofol on chemoreceptor function are however clearly complex and require further investigation.

Effect of dexmedetomidine on blood coagulation in patients undergoing radical gastrectomy under general anesthesia: A prospective, randomized controlled clinical trial

BACKGROUND

Dexmedetomidine can inhibit the perioperative stress response, which plays an important role in postoperative hypercoagulability. This study aimed to investigate whether dexmedetomidine could attenuate the activation of postoperative coagulation.

METHODS

Patients undergoing open radical gastrectomy under total intravenous anesthesia were randomly allocated to the control group (group Con) and the dexmedetomidine group (group Dex). Dexmedetomidine was intravenously infused at 0.5 μg/kg over 10 minutes before anesthesia induction and then infused at a rate of 0.5 μg/kg/h until peritoneal closure in group Dex, whereas saline was administered in group Con. Blood samples were collected for thrombelastograph (TEG) analysis [reaction time (R time), clot formation time (K time), and clot formation rate (α angle)] and laboratory coagulation testing before dexmedetomidine administration and at the end of surgery.

RESULTS

Coagulation was activated after radical gastrectomy, as indicated by TEG analysis and the increased concentrations of plasma fibrin (fibrinogen) degradation product (FDP) and thrombin-antithrombin complex (TAT). The R and K times were significantly prolonged and α angle was significantly decreased in group Dex compared with that in group Con at the end of surgery (P < .05). The concentrations of plasma TAT and FDP in group Dex were significantly lower than those in group Con at the end of surgery (P < .05 or .01).

CONCLUSION

Adjunctive dexmedetomidine with general anesthesia attenuates the activation of coagulation following radical gastrectomy.

The influence of drugs used in cardiac anaesthesia and critical care on multiple electrode aggregometry: an in-vitro volunteer study

BACKGROUND

Multiple electrode aggregometry (MEA) is a point-of-care test evaluating platelet function and the efficacy of platelet inhibitors. In MEA, electrical impedance of whole blood is measured after addition of a platelet activator. Reduced impedance implies platelet dysfunction or the presence of platelet inhibitors. MEA plays an increasingly important role in the management of perioperative platelet dysfunction. In vitro, midazolam, propofol, lidocaine and magnesium have known antiplatelet effects and these may interfere with MEA interpretation.

OBJECTIVE

To evaluate the extent to which MEA is modified in the presence of these drugs.

DESIGN

An in-vitro study using blood collected from healthy volunteers.

SETTING

Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland, 2010 to 2011.

PATIENTS

Twenty healthy volunteers.

INTERVENTION

Measurement of baseline MEA was using four activators: arachidonic acid, ADP, TRAP-6 and collagen. The study drugs were then added in three increasing, clinically relevant concentrations.

MAIN OUTCOME MEASURE

MEA was compared with baseline for each study drug.

RESULTS

Midazolam, propofol and lidocaine showed no effect on MEA at any concentration. Magnesium at 2.5 mmol l had a significant effect on the ADP and TRAP tests (31 ± 13 and 96 ± 39 AU, versus 73 ± 21 and 133 ± 28 AU at baseline, respectively), and a less pronounced effect at 1 mmol l on the ADP test (39 ± 0 AU).

CONCLUSION

Midazolam, propofol and lidocaine do not interfere with MEA measurement. In patients treated with high to normal doses of magnesium, MEA results for ADP and TRAP-tests should be interpreted with caution.

TRIAL REGISTRATION

Clinicaltrials.gov (no. NCT01454427).

Propofol inhibits lipopolysaccharide-induced tumor necrosis factor-alpha expression and myocardial depression through decreasing the generation of superoxide anion in cardiomyocytes

TNF-α has been shown to be a major factor responsible for myocardial depression in sepsis. The aim of this study was to investigate the effect of an anesthetic, propofol, on TNF-α expression in cardiomyocytes treated with LPS both in vivo and in vitro. In cultured cardiomyocytes, compared with control group, propofol significantly reduced protein expression of gp91phox and phosphorylation of extracellular regulated protein kinases 1/2 (ERK1/2) and p38 MAPK, which associates with reduced TNF-α production. In in vivo mice studies, propofol significantly improved myocardial depression and increased survival rate of mice after LPS treatment or during endotoxemia, which associates with reduced myocardial TNF-α production, gp91phox, ERK1/2, and p38 MAPK. It is concluded that propofol abrogates LPS-induced TNF-α production and alleviates cardiac depression through gp91phox/ERK1/2 or p38 MAPK signal pathway. These findings have great clinical importance in the application of propofol for patients enduring sepsis.

Dexmedetomidine decreases the requirement of ketamine and propofol during burns debridement and dressings

Background and Aims:

Dexmedetomidine (Dex), a highly selective α₂-adrenoreceptor agonist, is used for sedation management in various clinical settings and shows anaesthetic-sparing effect. Our aim was to study the effects of Dex on requirements of propofol, ketamine, and intraoperative haemodynamic variations during burns debridement and dressing changes, and compare its effectiveness and safety with combination of ketamine and propofol.

Methods:

Sixty adult patients posted for elective debridement and dressing were included in the study. Thirty patients received Dex (intramuscular)(IM) 1 μg/kg, 1 h before shifting to the operation theatre while the other thirty did not. Anaesthesia was induced with propofol and ketamine followed by adjusted infusion to achieve a Ramsay Sedation Scale score (RSS) of six in all patients. Intraoperatively haemodynamic parameters were recorded at regular intervals of 5, 15, 30, 45, and 60 min. The mean data between the groups were compared by unpaired t test and medians by Mann-Whitney U test. Within group analysis was performed by using repeated measures ANOVA. P < 0.05 was considered significant.

Results:

The dose requirement of ketamine and propofol in Dex group was significantly lower when compared to control group (100.5 ± 17.58 mg vs. 231.5 ± 60.39 mg (P < 0.0001) and 127.7 ± 15.47 mg vs. 254 ± 59.22 mg (P < 0.0001) respectively). Additionally, recovery time was lower in the Dex group as compared to the control group, 9.57 ± 1.50 min vs. 11.53 ± 2.56 min (P = 0.0006). Haemodynamic variations were also significantly lower in the Dex group as compared to the control group.

Conclusion:

Dexmedetomidine (1 μg/kg IM) reduced the requirement of propofol and ketamine, with more stable intraoperative haemodynamics.

In vitro effect of clinical propofol concentrations on platelet aggregation

The inhibitory effect of propofol on platelet aggregation remains unclear, and studies on the subject disagree. Furthermore, although propofol infusions are widely used for general anesthesia and as sedatives for patients in intensive care units, little information is available on its concentration- and time-related effects on platelet aggregation. Here, the authors investigated the in vitro effect of propofol, at concentrations required for sedation and general anesthesia, on platelet aggregation after 1, 2, or 3 h. Blood from healthy volunteers (n = 9) was incubated at propofol plasma concentrations of 0, 2, 4, and 10 μg/mL in a water bath at 37°C. Platelet aggregation was measured using a platelet function analyzer (PFA-100) after 1, 2, or 3 h of incubation. Times to occlude collagen/epinephrine (CEPI) or collagen/adenosine 5'-diphosphate (CADP)-coated membranes (closure times, CTs) were measured. The CEPI and CADP CTs of non-incubated blood were 125.6 ± 19.5 s and 93.0 ± 12.2 s, respectively, and no significant difference in CEPI CTs was observed at propofol plasma concentrations of 0, 2, 4, and 10 μg/mL after incubation for 1, 2, or 3 h. CADP CTs were comparable at propofol concentrations of 0, 2, 4, and 10 μg/mL at each incubation time. These findings suggest that propofol at concentrations required for sedation and general anesthesia has no inhibitory effect on platelet aggregation after 3 h of incubation.

Preliminary experience with a combination of dexmedetomidine and propofol infusions for diagnostic cardiac catheterization in children

No specific regimen has been universally accepted as ideal for procedural sedation during cardiac catheterization in infants and children. In this paper, we retrospectively describe our preliminary experience with a continuous infusion of dexmedetomidine and propofol for sedation during cardiac catheterization in children with congenital heart disease. The short-half life of these two drugs creates a potential for easier titration, quicker recovery and less prolonged sedation-related adverse effects. This combination was not only able to limit the dose of either drugs, but was also very stable from cardio-respiratory standpoint. There were no adverse effects noted in our two patients. This initial experience showed that the combination of propofol and dexmedetomidine as a continuous infusion may be a suitable alternative for sedation in spontaneously breathing children undergoing cardiac catheterization.

The effect of dexmedetomidine on the adjuvant propofol requirement and intraoperative hemodynamics during remifentanil-based anesthesia

BACKGROUND

The effects of dexmedetomidine on the propofol-sparing effect and intraoperative hemodynamics during remifentanil-based propofol-supplemented anesthesia have not been well investigated.

METHODS

Twenty patients undergoing breast surgery were randomly allocated to receive dexmedetomidine (group DEX) or placebo (group C). In the DEX group, dexmedetomidine was loaded (1 µg/kg) before anesthesia induction and was infused (0.6 µg/kg/h) during surgery. Anesthesia was induced with a target-controlled infusion (TCI) of propofol (effect site concentration, Ce; 3 µg/ml) and remifentanil (plasma concentration, Cp, 10 ng/ml). The Ce of TCI-propofol was adjusted to a bispectral index of 45-55, and Cp of TCI-remifentanil was fixed at 10 ng/ml in both groups. Mean arterial blood pressure (MAP) and heart rate (HR) were recorded at baseline (T-control), after the loading of study drugs (T-loading), 3 min after anesthesia induction (T-induction), tracheal intubation (T-trachea), incision (T-incision), 30 min after incision (T-incision30), and at tracheal extubation (T-extubation). MAP% and HR% (MAP and HR vs. T-control) were determined and the propofol infusion rate was calculated.

RESULTS

The propofol infusion rate was significantly lower in the DEX group than in group C (63.9 ± 16.2 vs. 96.4 ± 10.0 µg/kg/min, respectively; P < 0.001). The changes in MAP% at T-induction, T-trachea and T-incision in group DEX (-10.0 ± 3.9%, -9.4 ± 4.6% and -11.2 ± 6.3%, respectively) were significantly less than those in group C (-27.6 ± 13.9%, -21.7 ± 17.1%, and -25.1 ± 14.1%; P < 0.05, respectively).

CONCLUSIONS

Dexmedetomidine reduced the propofol requirement for remifentanil-based anesthesia while producing more stable intraoperative hemodynamics.

Anesthetic management as a risk factor for postpartum hemorrhage after cesarean deliveries

OBJECTIVE

This population-based study aimed to compare the risk of postpartum hemorrhage (PPH) for patients who underwent cesarean section delivery (CS) with general vs spinal/epidural anesthesia.

STUDY DESIGN

We identified 67,328 women who had live singleton births by CS by linking the Taiwan National Health Insurance Research Dataset and the national birth certificate registry. Multivariate logistic regression was carried out to explore the relationship between anesthetic management type and PPH.

RESULTS

Women who received general anesthesia had a higher rate of PPH than women who received epidural anesthesia (5.1% vs 0.4%). The odds of PPH in women who had CS with general anesthesia were 8.15 times higher (95% confidence interval, 6.43-10.33) than for those who had CS with epidural anesthesia, after adjustment was made for the maternal and fetal characteristics.

CONCLUSION

The odds that women will experience cesarean PPH with general anesthesia are approximately 8.15 times higher than for women who undergo CS with epidural anesthesia.

Effects of dexmedetomidine on propofol and remifentanil infusion rates during total intravenous anesthesia for spine surgery in adolescents

INTRODUCTION

Total intravenous anesthesia with propofol and a synthetic opioid is a frequently chosen anesthetic technique for posterior spinal fusion. Despite its utility, adverse effects may occur with high or prolonged propofol dosing regimens including delayed awakening. The current study investigated the propofol-sparing effects of the concomitant administration of the alpha(2)-adrenergic agonist, dexmedetomidine, during spinal fusion surgery in adolescents.

METHODS

The surgical database of the department of orthopedic surgery was searched and patients (12-21 years of age) were identified who had undergone spinal fusion for either idiopathic or neuromuscular scoliosis during the past 24 months. Patients were assigned to two groups. Group 1 included patients anesthetized with propofol and remifentanil and group 2 included patients anesthetized with dexmedetomidine, propofol, and remifentanil. In the latter group, dexmedetomidine was administered as a continuous infusion of 0.5 microg.kg(-1).h(-1) started after the induction of anesthesia without a loading dose. Propofol was adjusted to maintain the bispectral index (BIS) number at 40-50 and remifentanil was adjusted to maintain the mean arterial pressure (MAP) at 50-65 mmHg. Labetolol or hydralazine was used if the MAP could not be maintained at 50-65 mmHg with remifentanil up to a maximum dose of 0.6 microg/kg/min. Statistical analysis included a nonpaired t-test for parametric data (age, weight, remifentanil/propofol infusion requirements, and heart rate/blood pressure values). A nonparametric statistical analysis (Dunn) was used to compare BIS numbers. Parametric data are presented as the mean +/- SD while nonparametric data are presented as the median and the 95th percentile confidence intervals.

RESULTS

Twelve patients received propofol-remifentanil-dexmedetomidine and 24 received propofol-remifentanil. There were no differences in the demographic data, BIS numbers or hemodynamic parameters between the two groups. There was a reduction in the propofol infusion requirements in patients who also received dexmedetomidine (71 +/- 11 microg.kg(-1).min(-1)) compared with those receiving only propofol-remifentanil (101 +/- 33 microg.kg(-1).min(-1), P = 0.0045). No difference was noted in the remifentanil infusion requirements or the use of supplemental agents (hydralazine and labetolol) to maintain controlled hypotension.

CONCLUSION

The concomitant use of dexmedetomidine in patients undergoing spinal fusion reduces propofol infusion requirements when compared with those patients receiving only propofol and remifentanil.

Propofol: an immunomodulating agent

Propofol (2,6-diisopropylphenol) is a potent intravenous hypnotic agent widely administered for induction and maintenance of anesthesia and for sedation in the intensive care unit. Propofol is insoluble in water and therefore is formulated in a lipid emulsion. In addition, a preservative (ethylenediaminetetraacetic acid [EDTA] or sodium metabisulfite) is added to retard bacterial growth. Propofol has antiinflammatory properties, decreasing production of proinflammatory cytokines, altering expression of nitric oxide, and inhibiting neutrophil function. Propofol also is a potent antioxidant. The added preservatives have biologic activity; EDTA has antiinflammatory properties, whereas metabisulfite may cause lipid peroxidation. The antiinflammatory and antioxidant properties of propofol may have beneficial effects in patients with sepsis and systemic inflammatory response syndrome.