Ketamine: new uses for an old drug

Pre-adolescence repeat exposure to sub-anesthetic doses of ketamine induces long-lasting behaviors and cognition impairment in male and female rat adults

In pre-adolescence, repeated anesthesia may be required for therapeutic interventions. Adult cognitive and neurobehavioral problems may result from preadolescent exposure to anesthetics. This study examined the long-term morphological and functional effects of repeated sub-anesthetic doses of ketamine exposure on male and female rat adults during pre-adolescence. Weaned 48 pre-adolescent rats from eight mothers and were randomly divided into four equal groups: control group and the ketamine group of males and females (20 mg/kg daily for 14 days); then animals received care for 20-30 days. Repeated exposure to sub-anesthetic doses of ketamine on cognitive functions was assayed using Social discrimination and novel object tests. Besides, an elevated plus maze and fear conditioning apparatus were utilized to determine exploratory and anxiety-like behavior in adults. Toluidine blue stain was used to evaluate the number of dead neurons in the hippocampus, and the effects of ketamine on synaptic plasticity were compared in the perforant pathway of the CA1 of the hippocampus. Our study indicates that repeated exposure to sub-anesthetic doses of ketamine during pre-adolescence can result in neurobehavioral impairment in male and female rat adulthood but does not affect anxiety-like behavior. We found a significant quantifiable increase in dark neurons. Recorded electrophysiologically, repeat sub-anesthetic doses of ketamine resulted in hampering long-term potentiation and pair pulse in male adult animals. Our results showed that repeated exposure to sub-anesthetic doses of ketamine during pre-adolescence can induce hippocampus and neuroplasticity changes later in adulthood. This study opens up a new line of inquiry into potential adverse outcomes of repeated anesthesia exposure in pre-adolescent rats.

The role of ketamine in major depressive disorders: Effects on parvalbumin-positive interneurons in hippocampus

Major depressive disorder (MDD) is a complex illness that is arising as a growing public health concern. Although several brain areas are related to this type of disorders, at the cellular level, the parvalbumin-positive cells of the hippocampus interplay a very relevant role. They control pyramidal cell bursts, neuronal networks, basic microcircuit functions, and other complex neuronal tasks involved in mood disorders. In resistant depressions, the efficacy of current antidepressant treatments drops dramatically, so the new rapid-acting antidepressants (RAADs) are being postulated as novel treatments. Ketamine at subanesthetic doses and its derivative metabolites have been proposed as RAADs due to their rapid and sustained action by blocking N-methyl-d-aspartate (NMDA) receptors, which in turn lead to the release of brain-derived neurotrophic factor (BDNF). This mechanism produces a rapid plasticity activation mediated by neurotransmitter homeostasis, synapse recovery, and increased dendritic spines and therefore, it is a promising therapeutic approach to improve cognitive symptoms in MDD.

Intranasal Ketamine Administration for Narcotic Dose Decrement in Patients Suffering from Acute Limb Trauma in Emergency Department: a Double-Blind Randomized Placebo-Controlled Trial

Introduction:

pain management is an important and challenging issue in emergency medicine. Despite the conduct of several studies on this topic, pain is still handled improperly in many cases.

Objective:

This study investigated the effectiveness of low-dose IN ketamine administration in reducing the need for opiates in patients in acute pain resulting from limb injury.

Method:

This randomized, double-blind, placebo-controlled trial was conducted to assess the possible effect of low-dose intranasal (IN) ketamine administration in decreasing patients' narcotic need. Patients in emergency department suffering from acute isolated limb trauma were included. One group of patients received 0.5 mg/kg intravenous morphine sulfate and 0.02 ml/kg IN ketamine. The other group received the same dose of morphine sulfate and 0.02 ml/kg IN distilled water. Pain severity was measured using the 11 points numerical rating scale at 0, 10, 30, 60, 120, and 180 minutes.

Results:

Ninety-one patients with mean age of 31.59 ± 11.33 years were enrolled (38.8% female). The number of requests for supplemental medication was significantly lower in patients who received ketamine (12 patients (30%)) than those who received placebo (27 patients (67.5%)) (p = 0.001).

Conclusion:

It is likely that low-dose IN ketamine is effective in reducing the narcotic need of patients suffering from acute limb trauma.

A retrospective study of ketamine administration and the development of acute or post-traumatic stress disorder in 274 war-wounded soldiers

The objective of this study was to explore whether ketamine prevents or exacerbates acute or post-traumatic stress disorders in military trauma patients. We conducted a retrospective study of a database from the French Military Health Service, including all soldiers surviving a war injury in Afghanistan (2010-2012). The diagnosis of post-traumatic stress disorder was made by a psychiatrist and patients were analysed according to the presence or absence of this condition. Analysis included the following covariables: age; sex; acute stress disorder; blast injury; associated fatality; brain injury; traumatic amputation; Glasgow coma scale; injury severity score; administered drugs; number of surgical procedures; physical, neurosensory or aesthetic sequelae; and the development chronic pain. Covariables related to post-traumatic and acute stress disorders with a p ≤ 0.10 were included in a multivariable logistic regression model. The data from 450 soldiers were identified; 399 survived, of which 274 were analysed. Among these, 98 (36%) suffered from post-traumatic stress disorder and 89 (32%) had received ketamine. Fifty-four patients (55%) in the post-traumatic stress disorder group received ketamine vs. 35 (20%) in the no PTSD group (p < 0.001). The 89 injured soldiers who received ketamine had a median (IQR [range]) injury severity score of 5 (3-13 [1-26]) vs. 3 (2-4 [1-6] in the 185 patients who did not (p < 0.001). At multivariable analysis, only acute stress disorder and total number of surgical procedures were independently associated with the development of post-traumatic stress disorder. In this retrospective study, ketamine administration was not a risk factor for the development of post-traumatic stress disorder in the military trauma setting.

Ketamine and propofol combination ("ketofol") for endotracheal intubations in critically ill patients: a case series

BACKGROUND

Endotracheal intubation is a common procedure performed for critically ill patients that can have immediate life-threatening complications. Induction medications are routinely given to facilitate the procedure, but most of these medications are associated with hypotension. While etomidate is known for its neutral hemodynamic profile, it has been linked with increased mortality in septic patients and increased morbidity in trauma patients. Ketamine and propofol are effective anesthetics with counteracting cardiovascular profiles. No data are available about the use of this combination in critically ill patients undergoing endotracheal intubation.

CASE REPORT

We describe 6 cases in which the combination of ketamine and propofol ("ketofol") was used as an induction agent for endotracheal intubation in critically ill patients with a focus on hemodynamic outcomes. All patients received a neuromuscular blocker and fentanyl, while 5 patients received midazolam. We recorded mean arterial pressure (MAP) 1 minute before induction and 15 minutes after intubation with the combination. Of the 6 patients, 5 maintained a MAP ≥ 65 mmHg 15 minutes after intubation. One patient was on norepinephrine infusion with a MAP of 64 mmHg, and did not require an increase in the dose of the vasopressor 15 minutes after intubation. No hemodynamic complications were reported after any of the intubations.

CONCLUSIONS

This case series describes the use of the "ketofol" combination as an induction agent for intubation in critically ill patients when hemodynamic stability is desired. Further research is needed to establish the safety of this combination and how it compares to other induction medications.

Wherefore ketamine?

PURPOSE OF REVIEW

Ketamine has been repeatedly reviewed in this journal but novel developments have occurred in the last few years prompting an update. Interesting recent publications will be highlighted against a background of established knowledge.

RECENT FINDINGS

In the field of anesthesia, particularly in pediatrics, some contributions have been made concerning intramuscular versus intravenous induction. The need for anticholinergic adjuvants has also been clarified. Neuroapoptosis has been observed in animals and its implications for human subjects are discussed in a general context of neurotoxicity. The most important developments, however, are in the treatment of pain. Neurological and urological side effects strongly question long-term use. Other potentially beneficial effects have also been reported, such as anti-inflammatory and antidepressive effects. There are also indications that ketamine may attenuate postoperative delirium in coronary by-pass patients.

SUMMARY

More questions have arisen than have been answered. Some have very grave implications. The issue of neuroapoptosis must be clarified. The long-term effects must be further investigated. On the bright side the effects on postoperative delirium, as well as the anti-inflammatory and antidepressive effects, might open new vistas for an old drug.

General anaesthesia in elderly patients with cardiovascular disorders: choice of anaesthetic agent

Our population is aging; currently 15% of the Western population are aged >65 years, and represent 25% of those undergoing surgery. The proportion of the population aged >or=65 years is rapidly growing, and an increasing number are affected with cardiovascular disease. The older person is a high-risk patient. This is because of their altered physiology and associated co-morbidities, as well as the pharmacokinetic and pharmacodynamic changes that may alter drug responses. There is considerable variability seen in the physical and physiological states of individual patients within the older population. This has an important impact on choosing a safe anaesthetic technique for each individual, which in turn can influence the morbidity and mortality in this population. The physiological changes in the aging cardiovascular system affect the arterial and venous vasculature, myocardium and autonomic nervous system, making the older person more prone to cardiovascular instability. In addition to the physiological changes, the cardiovascular status of the older person tends to be compromised by associated pathological conditions that are more common with increasing age. Pharmacokinetic and pharmacodynamic changes must be taken into account when deciding about drug dosing in this age group. Aspects of dose reduction, titration of drugs, dosing intervals and the pharmacodynamic effects of each class of drug are explained in detail in the text. The major challenge in anaesthesia for the older person with cardiovascular disease is maintenance of haemodynamic stability, particularly in the face of reduced physiological reserve and capability to respond to periods of instability. An appropriate anaesthetic technique must be selected to minimize haemodynamic changes and maintain near normal physiological status. The other key objective is to minimize the incidence of adverse outcomes, such as perioperative myocardial ischaemia/infarction, arrhythmias, heart failure, postoperative cognitive dysfunction and stroke. No single anaesthetic regimen or agent can be advocated. Knowledge of the pharmacokinetic and pharmacodynamic principles of anaesthetic agents and their altered response in elderly patients is essential when selecting an anaesthetic agent. This article provides a practical guide to the selection and use of general anaesthetic agents in older patients with cardiovascular disorders, highlighting the differences among various agents.

The evolution of ketamine applications in children

Ketamine has found many applications in pediatric anesthetic practice. Insights into the mechanism of action and the pharmacokinetics and pharmacodynamics of its isomers have led to a re-evaluation of this drug, expanding the range of applications in children. Ketamine is a remarkably versatile drug that can be administered through almost any route. It can also be used for different purposes. The aim of this review is to look at the possible applications of this drug in children.

Randomised, cross-over comparison of sevoflurane and ketamine-midazolam anaesthesia in children undergoing extracorporeal shock-wave lithotripsy

INTRODUCTION

The aim of this study was to assess the haemodynamic responses, adverse events and recovery characteristics associated with sevoflurane and ketamine-midazolam anaesthesia for paediatric extracorporeal shock-wave lithotripsy.

METHODS

Twenty children aged 2-11 years, who were undergoing two consecutive lithotripsy sessions at an interval of 4 weeks were enrolled and randomised to receive either inhalation or dissociative anaesthesia at their first session. The alternative anaesthesia protocol was used at their second session. Inhalation anaesthesia was induced with 8% sevoflurane and 70% N(2)O in oxygen; 10 microg/kg atropine and 2 microg/kg fentanyl were then administered. Anaesthesia was maintained with 2%-3% end-tidal sevoflurane and 70% N(2)O in oxygen via a laryngeal mask airway. Dissociative anaesthesia was induced intravenously with 10 mug/kg atropine, 0.05 mg/kg midazolam, 1.5 mg/kg ketamine and maintained with 0.5-1.0 mg/kg ketamine. Haemodynamic parameters were recorded before and after induction, after the start of the procedure, and every 10 minutes thereafter. Postoperatively, the times to responding to command, sitting, ambulating, achieving an Aldrete score > or = 9, and achieving a post-anaesthetic discharge score > or = 9 were recorded.

RESULTS

Systolic and diastolic arterial pressures at all measurements throughout the procedure were higher with ketamine-midazolam than with sevoflurane (P<0.05). Heart rates were comparable between groups, except after induction and after start of the procedure in which they were higher with ketamine-midazolam (P<0.05). All recovery endpoints were achieved earlier with sevoflurane than with ketamine-midazolam (P<0.05). Nausea-vomiting incidences were similar in both groups.

CONCLUSION

Sevoflurane and ketamine-midazolam both provided effective anaesthesia for paediatric lithotripsy. The recovery and discharge times were shorter after anaesthesia with sevoflurane compared with ketamine-midazolam in children undergoing lithotripsy.

Sedation with ketamine and low-dose midazolam for short-term procedures requiring pharyngeal manipulation in young children

BACKGROUND

Pediatric intestinal biopsy procedures including considerable transpharyngeal manipulation of a wire-guided metal capsule require adequate sedation or anesthesia. This retrospective cohort study was designed to evaluate intravenous sedation with ketamine and low-dose midazolam in young children undergoing these procedures before and also after discharge from the hospital.

METHODS

A total of 244 biopsy procedures in 217 children under the age of 16 years were evaluated. All anesthesia records were reviewed according to a defined study protocol and in 145 cases the parents were also interviewed by telephone to obtain further information on possible adverse effects before and after discharge.

RESULTS

Ketamine and low-dose midazolam were carefully titrated by an experienced anesthesia team at an approximate dose ratio of 40 : 1 (total doses 2.3 and 0.05 mg.kg(-1)) in continuously monitored spontaneously breathing children. Possibly associated problems before discharge were salivation (5.7%), vomiting (4.9%), oxygen desaturation (3.3%), laryngospasm (2.5%) and rash (1.2%) according to the patient records and blurred vision (27%), nausea and vomiting (19%), vertigo (13%) and hallucinations or nightmares (3.5%) according to telephone interviews. Few, mild and transient problems remained after discharge from the hospital.

CONCLUSIONS

Careful titration of ketamine and low-dose midazolam provides adequate sedation for nonsurgical pediatric short-term procedures also requiring considerable pharyngeal manipulation, particularly considering the low number of serious airway problems such as laryngospasm. The high incidence of late postoperative problems suggests that prospective studies should be designed for long-term follow-up of young children subjected to sedation or anesthesia.

The clinical role of NMDA receptor antagonists for the treatment of postoperative pain

Recent advances in the understanding of postoperative pain have demonstrated its association with sensitization of the central nervous system (CNS) which clinically elicits pain hypersensitivity. N-methyl-D-aspartate (NMDA) receptors play a major role in synaptic plasticity and are specifically implicated in CNS facilitation of pain processing. Therefore, NMDA receptor antagonists, and specifically ketamine commonly used in clinical practice, have been implicated in perioperative pain management. At subanesthetic (i.e. low) doses, ketamine exerts a specific NMDA blockade and hence modulates central sensitization induced both by the incision and tissue damage and by perioperative analgesics such as opioids. However, the mechanisms underlying ketamine anti-hyperalgesic effect are not totally understood, and neither is the relationship between central sensitization and the risk of developing residual pain after surgery. This chapter examines the role of low doses of ketamine as an adjuvant drug in current perioperative pain management and questions the anti-hyperalgesic mechanisms involved.

Ketamine and postoperative pain – a quantitative systematic review of randomised trials

Ketamine, an N-methyl-D-aspartate receptor antagonist, is known to be analgesic and to induce psychomimetic effects. Benefits and risks of ketamine for the control of postoperative pain are not well understood. We systematically searched for randomised comparisons of ketamine with inactive controls in surgical patients, reporting on pain outcomes, opioid sparing, and adverse effects. Data were combined using a fixed effect model. Fifty-three trials (2839 patients) from 25 countries reported on a large variety of different ketamine regimens and surgical settings. Sixteen studies tested prophylactic intravenous ketamine (median dose 0.4 mg/kg, range (0.1-1.6)) in 850 adults. Weighted mean difference (WMD) for postoperative pain intensity (0-10 cm visual analogue scale) was -0.89 cm at 6 h, -0.42 at 12 h, -0.35 at 24 h and -0.27 at 48 h. Cumulative morphine consumption at 24 h was significantly decreased with ketamine (WMD -15.7 mg). There was no difference in morphine-related adverse effects. The other 37 trials tested in adults or children, prophylactic or therapeutic ketamine orally, intramuscularly, subcutaneously, intra-articulary, caudally, epidurally, transdermally, peripherally or added to a PCA device; meta-analyses were deemed inappropriate. The highest risk of hallucinations was in awake or sedated patients receiving ketamine without benzodiazepine; compared with controls, the odds ratio (OR) was 2.32 (95%CI, 1.09-4.92), number-needed-to-harm (NNH) 21. In patients undergoing general anaesthesia, the incidence of hallucinations was low and independent of benzodiazepine premedication; OR 1.49 (95%CI 0.18-12.6), NNH 286. Despite many published randomised trials, the role of ketamine, as a component of perioperative analgesia, remains unclear.

Evaluation of the neuroprotective effects of S(+)-ketamine during open-heart surgery

We compared the effect of S(+)-ketamine to remifentanil, both in combination with propofol, on the neurocognitive outcome after open-heart surgery in 106 patients. A battery of neurocognitive tests was administered before surgery and 1 and 10 wk after surgery. Fourteen patients (25%) in the control group and 10 patients (20%) in the S(+)-ketamine group had 2 or more tests with a cognitive deficit (decline by at least one preoperative SD of that test in all patients) 10 wk after surgery (P = 0.54). Z-scores were calculated for all tests. No significantly better performance could be detected in the S(+)-ketamine group, except for the Trailmaking B test 10 wk after surgery. We conclude that S(+)-ketamine offers no greater neuroprotection compared with remifentanil during open-heart surgery.

IMPLICATIONS

N-methyl-D-aspartic acid receptors play an important role during ischemic brain injury. We could not demonstrate that S(+)-ketamine resulted in greater neuroprotective effects compared with remifentanil during cardiopulmonary bypass procedures when both were combined with propofol.

Ketamine: In the past thirty years and in the future

Introduction There are two isomers of ketamine: S(+)ketamine and R(-) ketamine. Effects of this drug are mediated by N-methyl-D-aspartate (NMDA), opioid and muscarinic receptors. Pharmacokinetics Due to its high lipid solubility and low protein binding, ketamine is extensively distributed in the body. Ketamine metabolism is mediated by hepatic microsomal enzymes. Effects on body systems Ketamine causes increased intracranial pressure, bronchodilation and stimulation of cardiovascular system. Clinical use Anesthesia It is used for premedication, sedation, induction and maintenance of general anesthesia. Ketamine is an ideal anesthetic agent for trauma victims, patients with hypovolemic and septic shock, patients with pulmonary diseases. Analgesia Even subanesthetic doses of ketamine have analgesic effects, so ketamine is also recommended for postoperative analgesia. Recent results show that ketamine is not always effective as an analgesic in treatment of chronic pain and that some side effects limit its use in patients with chronic pain. Intensive care Combination of ketamine and midazolam can be very useful and safe for sedation and pain relief in intensive care patients, especially during ventilator management. Ketamine may be the anesthetic of choice for painful procedures in intensive care units. Emergency medicine Ketamine is recommended for critically ill patients with sedative, inotropic and bronchodilatatory effects. New clinical use Future studies will reveal if ketamine can be used for outpatient anesthesia, intravenous regional anesthesia and in treatment of depression. S(+)ketamine is a more effective anesthetic with significantly less psychomotor effects which provides rapid recovery from anesthesia in regard to racemate or R(-)ketamine. Conclusion Increasing interest in use of ketamine has resulted from current knowledge. In the future we expect new clinical uses in treatment of acute and chronic pain, intensive care and emergency medicine.

Pain relief and wound care in a young woman with special needs

This article focuses on a teenage girl with cerebral palsy admitted for an orthopaedic procedure, and highlights the problems of pain and wound management discussed in this journal's Challenges in Wound Care study days.

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.