Ketamine does not inhibit inflammatory responses of cultured human endothelial cells but reduces chemotactic activation of neutrophils

Effects of an intravenous ketamine infusion on inflammatory cytokine levels in male and female Sprague-Dawley rats

Background

Ketamine, a multimodal dissociative anesthetic drug, is widely used as an analgesic following traumatic injury. Although ketamine may produce anti-inflammatory effects when administered after injury, the immunomodulatory properties of intravenous (IV) ketamine in a non-inflammatory condition are unclear. In addition, most preclinical studies use an intraperitoneal (IP) injection of ketamine, which limits its clinical translation as patients usually receive an IV ketamine infusion after injury.

Methods

Here, we administered sub-anesthetic doses of a single IV ketamine infusion (0, 10, or 40 mg/kg) to male and female Sprague–Dawley rats over a 2-h period. We collected blood samples at 2- and 4-h post-ketamine infusion to determine plasma inflammatory cytokine levels using multiplex immunoassays.

Results

The 10 mg/kg ketamine infusion reduced spontaneous locomotor activity in male and female rats, while the 40 mg/kg infusion stimulated activity in female, but not male, rats. The IV ketamine infusion produced dose-dependent and sex-specific effects on plasma inflammatory cytokine levels. A ketamine infusion reduced KC/GRO and tumor necrosis factor alpha (TNF-α) levels in both male and female rats, interleukin-6 (IL-6) levels in female rats, and interleukin-10 (IL-10) levels in male rats. However, most cytokine levels returned to control levels at 4-h post-infusion, except for IL-6 levels in male rats and TNF-α levels in female rats, indicating a different trajectory of certain cytokine changes over time following ketamine administration.

Conclusions

The current findings suggest that sub-anesthetic doses of an IV ketamine infusion may produce sex-related differences in the effects on peripheral inflammatory markers in rodents, and further research is warranted to determine potential therapeutic effects of an IV ketamine infusion in an inflammatory condition.

Effects of Ketamine on Icam-1 Expression during Lipopolysaccharide Induced Acute Lung Injury in Rats

Introduction

Intercellular adhesion molecule-1 (ICAM-1) serves very important roles in lung injury, and increases in ICAM-1 are associated with severity of lung injury. We intended to examine whether ketamine could have favourable effects on ICAM-1 expression in lipopolysaccharide (LPS)-induced acute lung injury in the rat.

Methods

The acute lung injury was induced by instilling LPS into the tracheas of 72 anaesthetised rats. The animals were divided into four groups including a sham group with intratracheal saline, an LPS group with intratracheal LPS and intraperitoneal saline, and two ketamine treatment groups with intratracheal LPS and treated with 1 mg/kg or 10 mg/kg doses of intraperitoneal ketamine hydrochloride. Half of the animals were sacrificed at three hours and the remaining animals were sacrificed at six hours. Real time PCR was performed on the lung tissues obtained. Concentration of the soluble ICAM-1 was measured in the bronchoalveolar lavage fluid. Expression of ICAM-1 was measured.

Results

The transcriptional activity of ICAM-1 mRNA increased 9.92 fold in the LPS group compared to the sham group but decreased by 84.1% and 83.3%, respectively, in the 1 and 10 mg/kg ketamine treatment groups. The concentration of soluble ICAM-1 in bronchoalveolar lavage fluid increased 2.23 fold in the LPS group compared to the sham group while decreasing by 75.0% and 74.5% respectively in the 1 mg/kg and 10 mg/kg ketamine treatment groups. The intensity of immunohistochemical staining for ICAM-1 was also decreased in both ketamine treatment groups.

Conclusion

Ketamine attenuates ICAM-1 expression during acute lung injury in rats. (Hong Kong j.emerg.med. 2011;18:397-405)

Effect of particles of ashes produced from sugarcane burning on the respiratory system of rats

The practice of burning sugarcane obtained by non-mechanized harvesting exposes workers and the people of neighboring towns to high concentrations of particulate matter (PM) that is harmful to health, and may trigger a series of cardiorespiratory diseases. The aim of this study was to analyze the chemical composition of the micro-particles coming from sugarcane burning residues and to verify the effects of this micro-particulate matter on lung and tracheal tissues. Micro-particulate matter (PM10) was obtained by dissolving filter paper containing burnt residues in NaCl solution. This material was instilled into the Wistar rats' nostrils. Histological analyses (hematoxylin and eosin - HE) of cardiac, lung and tracheal tissues were performed. Inflammatory mediators were measured in lung tissues by using ELISA. The chemical composition of the particulate material revealed a large quantity of the phthalic acid ester, high concentrations of phenolic compounds, anthracene and polycyclic aromatic hydrocarbons (PAH). Histological analysis showed a reduction in subjacent conjunctive tissue in the trachea, lung inflammation with inflammatory infiltrate formation and reduction of alveolar spaces and a significant increase (p<0.05) in the release of IL-1α, IL-1β, IL-6, and INF-γ in the group treated with PM10 when compared to the control group. We concluded that the burning sugarcane residues release many particles, which have toxic chemical compounds. The micro-particulate matter can induce alterations in the respiratory system.

The immune response to anesthesia: part 2 sedatives, opioids, and injectable anesthetic agents

OBJECTIVE

To review the immune response to injectable anesthetics and sedatives and to compare the immunomodulatory properties between inhalation and injectable anesthetic protocols.

STUDY DESIGN

Review.

METHODS AND DATABASES

Multiple literature searches were performed using PubMed and Google Scholar from March 2012 through November 2013. Relevant anesthetic and immune terms were used to search databases without year published or species constraints. The online database for Veterinary Anaesthesia and Analgesia and the Journal of Veterinary Emergency and Critical Care were searched by issue starting in 2000 for relevant articles.

CONCLUSION

Sedatives, injectable anesthetics, opioids, and local anesthetics have immunomodulatory effects that may have positive or negative consequences on disease processes such as endotoxemia, generalized sepsis, tumor growth and metastasis, and ischemia-reperfusion injury. Therefore, anesthetists should consider the immunomodulatory effects of anesthetic drugs when designing anesthetic protocols for their patients.

Vibrio cholerae evades neutrophil extracellular traps by the activity of two extracellular nucleases

The Gram negative bacterium Vibrio cholerae is the causative agent of the secretory diarrheal disease cholera, which has traditionally been classified as a noninflammatory disease. However, several recent reports suggest that a V. cholerae infection induces an inflammatory response in the gastrointestinal tract indicated by recruitment of innate immune cells and increase of inflammatory cytokines. In this study, we describe a colonization defect of a double extracellular nuclease V. cholerae mutant in immunocompetent mice, which is not evident in neutropenic mice. Intrigued by this observation, we investigated the impact of neutrophils, as a central part of the innate immune system, on the pathogen V. cholerae in more detail. Our results demonstrate that V. cholerae induces formation of neutrophil extracellular traps (NETs) upon contact with neutrophils, while V. cholerae in return induces the two extracellular nucleases upon presence of NETs. We show that the V. cholerae wild type rapidly degrades the DNA component of the NETs by the combined activity of the two extracellular nucleases Dns and Xds. In contrast, NETs exhibit prolonged stability in presence of the double nuclease mutant. Finally, we demonstrate that Dns and Xds mediate evasion of V. cholerae from NETs and lower the susceptibility for extracellular killing in the presence of NETs. This report provides a first comprehensive characterization of the interplay between neutrophils and V. cholerae along with new evidence that the innate immune response impacts the colonization of V. cholerae in vivo. A limitation of this study is an inability for technical and physiological reasons to visualize intact NETs in the intestinal lumen of infected mice, but we can hypothesize that extracellular nuclease production by V. cholerae may enhance survival fitness of the pathogen through NET degradation.

Ketamine and peripheral inflammation

The old anesthetic ketamine has demonstrated interactions with the inflammatory response. This review intends to qualify the nature and the mechanism underlying this interaction. For this purpose, preclinical data will be presented starting with the initial works, and then, the probable mechanisms will be discussed. A summary of the most relevant clinical data will be presented. In conclusion, ketamine appears as a unique "homeostatic regulator" of the acute inflammatory reaction and the stress-induced immune disturbances. This is of some interest at a moment when the short- and long-term deleterious consequences of inadequate inflammatory reactions are increasingly reported. Large-scale studies showing improved patient's outcome are, however, required before to definitively assert the clinical reality of this positive effect.

Ketamine does not inhibit interleukin-6 synthesis in hepatic resections requiring a temporary porto-arterial occlusion (Pringle manoeuvre): a controlled, prospective, randomized, double-blinded study

INTRODUCTION

Previous studies have shown that interleukin-6 (IL-6) levels correlated with mortality in critically ill patients.

GOAL

To determine the effect of ketamine on IL-6 levels in liver resections patients with a temporary porto-arterial occlusion (Pringle manoeuvre).

MATERIALS AND METHODS

Controlled, prospective, randomized, double-blinded study. One group (n = 21) received ketamine whereas the other group (n = 17) received placebo. IL-6 levels were obtained at baseline, 4, 12, 24 h, 3 and 5 days.

RESULTS

There were no significant differences in IL-6 levels between the groups (basal P = 089, 4 hP = 0.83, 12 h P = 0.39, 24 h, P = 0.55, 3 days P = 0.80 and 5 days P = 0.45). Both groups had elevated IL-6 levels that became almost undetectable by day 5. There was no major morbidity and no mortality in either group.

CONCLUSIONS

  Ketamine does not seem to have an effect on plasma levels of IL-6. This could be interpreted as a potential finding associated with outcome as we did not encounter any deaths or major complications. Further studies will likely be needed to determine the range of IL-6 levels associated with survival and mortality, and whether it could be a predictor of survival.

Ketamine and the myenteric plexus in intestinal ischemia/reperfusion injury

BACKGROUND AND AIMS

Intestinal ischemia/reperfusion (I/R) is a common clinical entity with severe consequences. We studied the effects of ketamine and the participation of the myenteric plexus in I/R injury.

METHODS

Rats were divided into six groups: sham, IR (30 min ischemia/60 min reperfusion), KET+IR (50 mg/kg i.p. ketamine injection before I/R), DEN (myenteric plexus ablated with benzalkonium chloride (BAC) and sham operation performed), DEN+IR (BAC treated and I/R induced), and DEN+KET+IR (BAC treated, ketamine administered, and I/R induced). Serum concentrations of p-selectin, intracellular adhesion molecule-1 (ICAM-1), and antithrombin III (ATIII) were measured, and tissue samples were obtained for histological analysis.

RESULTS

IR group had higher intestinal mucosa injury and elevated serum concentrations of ICAM-1 and p-selectin, as well as ATIII depletion, compared with sham group (P < 0.05). In KET+IR group these alterations were significantly reduced (P < 0.05). DEN group showed ICAM-1 elevations when compared with sham group (P < 0.05), and DEN+IR group showed no difference in any parameter compared with IR group. However, ketamine administration in group DEN+KET+IR had no effect on any parameter when compared with DEN+IR group.

CONCLUSIONS

Ketamine was able to diminish alterations induced by I/R. Myenteric plexus ablation with BAC treatment alone had no effects on intestinal I/R injury. However, this procedure abolished ketamine's protective effects. Ketamine seems to require an intact enteric nervous system to exert its protective action.

Ketamine inhibits transcription factors activator protein 1 and nuclear factor-kappaB, interleukin-8 production, as well as CD11b and CD16 expression: studies in human leukocytes and leukocytic cell lines

BACKGROUND

Recent data indicate that ketamine exerts antiinflammatory actions. However, little is known about the signaling mechanisms involved in ketamine-induced immune modulation. In this study, we investigated the effects of ketamine on lipopolysaccharide-induced activation of transcription factors activator protein 1 (AP-1) and nuclear factor-kappaB (NF-kappaB) in human leukocyte-like cell lines and in human blood neutrophils.

METHODS

Electric mobility shift assays were used to investigate ketamine's effects on nuclear binding activity of both transcription factors in U937 cells, and a whole blood flow cytometric technique was used for AP-1 and NF-kappaB determination in leukocytes. Cell lines with different expression patterns of opioid and N-methyl-D-aspartate receptors were used for reverse transcription-polymerase chain reaction to investigate receptors involved in ketamine signaling. Ketamine's effect on interleukin-8 production was assessed in a whole blood assay.

RESULTS

Ketamine inhibited both transcription factors in a concentration-dependent manner. These effects did not depend on opiate or N-methyl-D-aspartate receptors. Ketamine also reduced interleukin-8 production in whole blood and expression of CD11b and CD16 on neutrophils.

CONCLUSION

The immunoinhibitory effects of ketamine are at least in part caused by inhibition of transcription factors NF-kappaB and AP-1, which regulate production of proinflammatory mediators. However, signaling mechanisms different from those present in the central nervous system are responsible for ketamine-mediated immunomodulation.

Ketamine-based total intravenous anesthesia versus isoflurane anesthesia in a swine model of hemorrhagic shock

BACKGROUND

Inhalational anesthetics can cause profound hemodynamic effects including decreases in systemic vascular resistance and cardiac inotropy. Although widely used in uncontrolled hemorrhagic shock (UHS), their consequences compared with other anesthetic regimens are not well-studied. Ketamine-based total intravenous anesthesia (TIVA) may produce less profound cardiovascular depression, and has been used during elective surgery but rarely during traumatic shock. The purpose of this study was to compare the effects of isoflurane (ISO) and TIVA regimens in a swine grade V liver injury model. We hypothesized that TIVA would result in less hypotension and dysfunctional inflammation than ISO.

METHODS

Twenty swine were randomized blindly to receive either 1% to 3% ISO, or intravenous ketamine, midazolam, and buprenorphine for maintenance anesthesia. Six animals acted as controls. After sedation and intubation, randomized anesthesia was initiated and monitored by an independent animal technician. Invasive lines were placed followed by celiotomy and splenectomy. Baseline mean arterial pressure (MAP) was documented and a grade V liver injury created. After 30 minutes of UHS, animals were resuscitated with 8 mL of Ringer's lactate per milliliter blood loss at 165 mL/min. MAP and tissue oxygen saturation (StO2) were continuously recorded. The animals were sacrificed 120 minutes after injury and lung tissue was harvested. Serum cytokines (interleukin-6 [IL-6], IL-8, and tumor necrosis factor-alpha [TNF-alpha]) were quantified with enzyme-linked immunosorbent assay. Lung cytokine mRNA levels were quantified with real time reverse transcriptase polymerase chain reaction.

RESULTS

Animal weight, liver injury pattern, and blood loss were similar (p > 0.1). The ISO group had a lower MAP at baseline (p = 0.02), at injury (p = 0.004), and study completion (p = 0.001). After resuscitation, MAP decreased in the ISO group but remained stable in the TIVA group. StO2 was significantly higher in the TIVA group immediately after injury (p = 0.004), but similar between groups throughout the remainder of the study. Animals who received TIVA trended toward higher levels of lactate and lower pH throughout the study, reaching significance at 30 minutes postinjury (p = 0.037 and 0.043). Inflammatory cytokine (IL-6, IL-8, and TNF-alpha) production did not differ between groups, however TNF-alpha mRNA production was significantly lower in the TIVA group (p = 0.04).

CONCLUSION

Although a TIVA regimen produced less pronounced hypotension in a swine model of UHS than did ISO, end-organ perfusion with TIVA appeared to be equivalent or inferior to ISO. In circumstances of limited resources, such as those experienced by forward Army surgical teams, a ketamine-based TIVA regimen may be an option for use in UHS.

Low-dose ketamine affects immune responses in humans during the early postoperative period

BACKGROUND

Anaesthesia and surgery are associated with impairment of the immune system expressed as an excessive proinflammatory immune response and suppression of cell-mediated immunity that may affect the course of the postoperative period. Addition of anaesthetic agents capable of attenuating the alterations in perioperative immune function may exert a favourable effect on patients' healing. We have assessed the effect of preoperative administration of a sub-anaesthetic dose of ketamine on the mitogen response and production of interleukin (IL)-1beta, IL-2, IL-6, and tumour necrosis factor (TNF)-alpha by peripheral blood mononuclear cells (PBMCs), as well as natural killer cell cytotoxicity (NKCC) in patients undergoing abdominal surgery.

METHODS

Seventeen patients admitted for elective abdominal surgery were given ketamine 0.15 mg kg(-1) i.v. 5 min before induction of general anaesthesia. Nineteen patients received a similar volume of isotonic saline 5 min before induction of the anaesthesia. PBMCs were isolated from venous blood before and 4, 24, 48, and 72 h after operation for IL-1beta, IL-2, IL-6, and TNF-alpha secretion, and NKCC assessment.

RESULTS

Four hours after operation, the cells from patients in the ketamine group showed a significantly suppressed production of IL-6 (P < 0.01) compared with controls. The production of IL-2 did not change from that of the preoperation samples. TNF-alpha secretion was significantly elevated in the control group 4 h after operation (P < 0.05).

CONCLUSIONS

Addition of small doses of ketamine before induction of anaesthesia resulted in attenuation of secretion of the proinflammatory cytokines IL-6 and TNF-alpha, and in preservation of IL-2 production at its preoperative level. It is suggested that this anaesthetic may be of value in preventing immune function alterations in the early postoperative period.

Pharmacodynamic effects and pharmacokinetic profile of a long-term continuous rate infusion of racemic ketamine in healthy conscious horses

Ketamine (KET) possesses analgesic and anti-inflammatory activity at sub-anesthetic doses, suggesting a benefit of long-term KET treatment in horses suffering from pain, inflammatory tissue injury and/or endotoxemia. However, data describing the pharmacodynamic effects and safety of constant rate infusion (CRI) of KET and its pharmacokinetic profile in nonpremedicated horses are missing. Therefore, we administered to six healthy horses a CRI of 1.5 mg/kg/h KET over 320 min following initial drug loading. Cardiopulmonary parameters, arterial blood gases, glucose, lactate, cortisol, insulin, nonesterified fatty acids, and muscle enzyme levels were measured, as were plasma concentrations of KET and its metabolites using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Levels of sedation and muscle tension were scored. Respiration and heart rate significantly increased during the early infusion phase. Glucose and cortisol significantly varied both during and after infusion. During CRI all horses scored 0 on sedation. All but one horse scored 0 on muscle tension, with one mare scoring 1. All other parameters remained within or close to physiological limits without significant changes from pre-CRI values. The mean plasma concentration of KET during the 1.5 mg/kg/h KET CRI was 235 ng/mL. The decline of its plasma concentration-time curve of both KET and norketamine (NKET) following the CRI was described by a two-compartmental model. The metabolic cascade of KET was NKET, hydroxynorketamine (HNK), and 5,6-dehydronorketamine (DHNK). The KET median elimination half-lives (t1/2alpha and t1/2beta) were 2.3 and 67.4 min, respectively. The area under the KET plasma concentration-time curve (AUC), elimination was 76.0 microg.min/mL. Volumes of C1 and C2 were 0.24 and 0.79 L/kg, respectively. It was concluded that a KET CRI of 1.5 mg/kg/h can safely be administered to healthy conscious horses for at least 6 h, although a slight modification of the initial infusion rate regimen may be indicated. Furthermore, in the horse KET undergoes very rapid biotransformation to NKET and HNK and DHNK were the major terminal metabolites.

INTRAVENOUS ANESTHESIA INHIBITS LEUKOCYTE-ENDOTHELIAL INTERACTIONS AND EXPRESSION OF CD11B AFTER HEMORRHAGE

Hemorrhage increases adhesion of leukocytes to the venular endothelium, mediated by increased expression of the Mac-1 integrin complex (CD18/CD11b) present on leukocytes. Anesthetic agents may possess anti-inflammatory properties. Hence, this study determined the effects of i.v. anesthesia on leukocyte adhesion after hemorrhage in relation to expression of CD11b.

METHODS

Male Wistar rats were (n = 57) anesthetized i.v. with propofol (Diprivan) and fentanyl, ketamine, or thiopental. During anesthesia, 10% of total blood volume was removed and intravital microscopy used to observe the rat mesentery and measure leukocyte (neutrophils) rolling and adhesion in postcapillary venules (15 - 25 microm). Flow cytometry was also used to determine CD11b expression on neutrophils from blood removed at the end of these experiments (n = 25) or blood incubated with anesthetic agents and activated with platelet activating factor ex vivo (0.1 micromol/L) (n = 24).

RESULTS

Hemorrhage increased leukocyte adhesion (stationary count per 150 microm) in rats anesthetized with thiopental (baseline, 3.4 +/- 1.2; hemorrhage, 6.7 +/- 2.0; P < 0.05) but not in those receiving either ketamine (baseline, 3.6 +/- 1.3; hemorrhage, 3.3 +/- 1.3) or propofol/fentanyl (baseline, 6.2 +/- 2.0; hemorrhage, 5.8 +/- 0.8). Neutrophils collected from thiopental-treated rats had elevated CD11b expression with thiopental (mean fluorescence baseline, 67.5 +/- 1.3; hemorrhage, 83.6 +/- 5.3; P < 0.05) but not with propofol/fentanyl (mean fluorescence baseline, 69.1 +/- 1.3; hemorrhage, 65.9 +/- 1.6), and ketamine-treated rats (mean fluorescence baseline, 74.3 +/- 2.1; hemorrhage, 74.8 +/- 1.1). Ketamine also inhibited upregulation of CD11b with platelet activating factor ex vivo.

CONCLUSIONS

After hemorrhage, leukocyte adhesion and CD11b expression increased during thiopental anesthesia, but propofol/fentanyl and ketamine protected against hemorrhage-induced leukocyte adhesion. The anti-inflammatory effect of ketamine was mediated by direct inhibition of CD11b expression on leukocytes.

Suppressive effects of ketamine on macrophage functions

Ketamine is an intravenous anesthetic agent. Clinically, induction of anesthesia with ketamine can cause immunosuppression. Macrophages play important roles in host defense. In this study, we attempted to evaluate the effects of ketamine on macrophage functions and its possible mechanism using mouse macrophage-like Raw 264.7 cells as the experimental model. Exposure of macrophages to 10 and 100 microM ketamine, which correspond to 0.1 and 1 times the clinically relevant concentration, for 1, 6, and 24 h had no effect on cell viability or lactate dehydrogenase release. When the administered concentration reached 1000 microM, ketamine caused a release of lactate dehydrogenase and cell death. Ketamine, at 10 and 100 microM, did not affect the chemotactic activity of macrophages. Administration of 1000 microM ketamine in macrophages resulted in a decrease in cell migration. Treatment of macrophages with ketamine reduced phagocytic activities. The oxidative ability of macrophages was suppressed by ketamine. Treatment with lipopolysaccharide induced TNF-alpha, IL-1beta, and IL-6 mRNA in macrophages. Administration of ketamine alone did not influence TNF-alpha, IL-1beta, or IL-6 mRNA production. Meanwhile, cotreatment with ketamine and lipopolysaccharide significantly inhibited lipopolysaccharide-induced TNF-alpha, IL-1beta, and IL-6 mRNA levels. Exposure to ketamine led to a decrease in the mitochondrial membrane potential. However, the activity of mitochondrial complex I NADH dehydrogenase was not affected by ketamine. This study shows that a clinically relevant concentration of ketamine (100 microM) can suppress macrophage function of phagocytosis, its oxidative ability, and inflammatory cytokine production possibly via reduction of the mitochondrial membrane potential instead of direct cellular toxicity.

Ketamine attenuates neutrophil activation after cardiopulmonary bypass

Surgery is associated with activation of neutrophils and their influx into affected tissue. The pathogenic role of superoxide production generated by activated neutrophils has been documented repeatedly. Ketamine suppresses neutrophil oxygen radical production in vitro. In the present study, we compared the effect of adding small-dose ketamine to opioids during the induction of general anesthesia on superoxide production by neutrophils after coronary artery bypass grafting (CABG). Thirty-five patients undergoing elective CABG were randomized to one of two groups and prospectively studied in a double-blinded manner. The patients received either ketamine 0.25 mg/kg or a similar volume of saline in addition to large-dose fentanyl anesthesia. Blood samples were drawn before the operation, immediately after cardiopulmonary bypass, 24 and 48 postoperative h, and on postoperative Days 3-6. Functional capacity of neutrophils was assessed by superoxide generation after stimulation with phorbol 12-myristate 13-acetate, opsonized zymosan, or formyl-methionyl-leucyl-phenylalanine. The addition of small-dose ketamine to general anesthesia attenuates increased production of the superoxide anion (O2-) by neutrophils without chemical stimulation and after stimulation with phorbol 12-myristate 13-acetate, formyl-methionyl-leucyl-phenylalanine, and opsonized zymosan for 4-6 days after CABG. In addition, ketamine attenuated the percentage of neutrophils on postoperative Days 2-6. In the Control group, superoxide production significantly increased compared with the baseline value. By contrast, in the Ketamine group, this difference was not significant.

IMPLICATIONS

In a randomized, double-blinded, prospective clinical study, we compared the effect of adding small-dose ketamine to opioids during general anesthesia on superoxide production and showed that ketamine suppressed the increase of superoxide anion production by neutrophils after coronary artery bypass grafting.

Ketamine: a new look at an old drug

Ketamine is a major drug for induction of patients with hypovolemia and for general anaesthesia under primitive conditions, but also has excellent properties for more generalized use in children, adults and other fragile patients. Potential beneficial effects on cardiac ischaemia and cerebral injury is presently explored, as well as the effects of ketamine as an potent analgesic drug. Combination with propofol or midazolam for sedation provides analgesia, sleep and spontaneous ventilation. The S-isomer of ketamine has a lower incidence of psychomimetic side effects in equianalgesic doses compared with the racemate or the R-isomer alone.

Ketamine: new uses for an old drug

Over the years, ketamine has found many applications in paediatric anaesthesiology. Recent insights into the mechanism of its central action, and the pharmacology of its isomers have led to a re-evaluation of this drug, expanding the range of indications in adults. The best examples of the uses of ketamine as an analgesic are: in brief diagnostic or therapeutic procedures, during the post-operative period in neonates and infants as well as in paediatric anaesthesia and intensive care.