Improved postoperative analgesia with coadministration of preoperative epidural ketamine and midazolam

Efficacy of prophylactic epidural ketamine for reducing shivering in patients undergoing caesarean section with combined spinal-epidural anesthesia

Intravenous ketamine is known to inhibit postoperative shivering; however, at present, there has been little research on whether this effect may be achieved with epidural application. The aim of the present study was to evaluate the efficacy and safety of epidural ketamine as a prophylactic agent to prevent shivering in patients undergoing caesarean section during combined spinal-epidural anesthesia. A prospective, randomized, double-blind study was performed. A total of 60 patients who were undergoing elective caesarean section under combined spinal-epidural anesthesia and had an American Society of Anesthesiologists physical status of I or II were recruited. Patients were randomly allocated to group S (epidural administration of normal saline; n=30) or group K (epidural ketamine 0.5 mg/kg; n=30). An investigator, blinded to the treatment groups, graded postoperative shivering using a 4-point scale and postoperative sedation on a 5-point scale. Operative time, hemodynamic changes and side effects, including hypotension, bradycardia, nausea and hallucinations, were recorded. The results demonstrated that patients' characteristics were not significantly different between groups. Heart rate, peripheral capillary oxygen saturation (SpO₂) values and Apgar scores at 1 and 5 min also did not differ significantly between groups. The incidence and severity of shivering in group K was significantly reduced compared with group S (P<0.05). The mean arterial pressure (MAP) was significantly different in groups S and K compared with baseline values at 10, 30 and 60 min (P<0.05). Furthermore, MAP values at 10, 30 and 60 min were significantly higher in group K compared with in group S (P<0.05). The results of the present study suggest that epidural administration of prophylactic low-dose ketamine may be an effective strategy for preventing postoperative shivering.

Preemptive Epidural Analgesia for Postoperative Pain Relief Revisited: Comparison of Combination of Buprenorphine and Neostigmine with Combination of Buprenorphine and Ketamine in Lower Abdominal Surgeries, A Double-blind Randomized Trial

Context:

Postoperative pain relief provides subjective comfort to patient in addition to blunting of autonomic and somatic reflex responses to pain, subsequently enhancing restoration of function by allowing the patient to breathe, cough, and move easily.

Aims:

The aim is to evaluate and compare the effects of neostigmine + buprenorphine and ketamine + buprenorphine for preemptive epidural analgesia for postoperative pain relief in patients undergoing abdominal surgeries under general anesthesia (GA).

Settings and Design:

A double-blind randomized trial.

Subjects and Methods:

A total of 60 American Society of Anesthesiologists physical status Classes I and II patients undergoing abdominal surgeries under GA were taken up for the study. They were randomly allocated into two groups, Group A and Group B of thirty patients each. Preemptive epidural analgesia for postoperative pain relief was provided by a combination of neostigmine 1 μg/kg + buprenorphine 2 μg/kg in Group A patients and ketamine 1 mg/kg + buprenorphine 2 μg/kg in Group B patients after induction of GA but before surgical incision. Postoperatively, vital parameters, pain score, requirement of top up doses, and side effects in the two groups were observed and recorded at 2, 4, 6, 10, 18, and 22 h.

Statistical Analysis Used:

Mean values within each of the Group A and Group B were compared using one-way analysis of variance (one-way ANOVA). Mean values between Group A and Group B were compared using double analysis of variance (two-way ANOVA).

Results:

Group A patients had a significant analgesia (visual analog scale [VAS] pain scores reduced significantly from 54.6 ± 6.3 at 2 h to 8.1 ± 8.9 at 22 h postoperatively). Group B patients had significant analgesia too (VAS pain scores reduced significantly from 36 ± 12.5 at 2 h to 5.3 ± 10.9 at 22 h postoperatively). There was however no significant difference between the two groups with respect to the degree of postoperative analgesia on comparison of VAS scores, effect on vital parameters, and incidence of side effects.

Conclusions:

Either of the two combinations, neostigmine 1 μg/kg + buprenorphine μg/kg or ketamine 1 mg/kg + buprenorphine 2 μg/kg can be safely used for preemptive epidural analgesia for postoperative pain relief in patients undergoing abdominal surgeries under GA.

Midazolam enhances the analgesic properties of dexmedetomidine in the rat

OBJECTIVE

To investigate the analgesic properties of different dose combinations of midazolam and dexmedetomidine administered intraperitoneally (IP) in the rat.

STUDY DESIGN

Prospective experimental trial.

ANIMALS

Seventy adult male Sprague Dawley rats weighing 250-300 g.

METHODS

Dexmedetomidine (D) 0.03, 0.06, 0.09, 0.12, 0.15, 0.18, 0.21 mg kg(-1) and midazolam (M) 5, 10, 25, 50 mg kg(-1) were administered IP, alone then in combinations ranging from 0.03 D:5 M to 0.18 D:30 M mg kg(-1). Analgesia was evaluated using the tail-flick test at time 0 (before injection), 15, 30, 45, 60 and 75 minutes.

RESULTS

Midazolam at all doses administered (5-50 mg kg(-1)) did not significantly change tail-flick latencies from baseline values whereas D showed clear dose-dependent increases in tail-flick latency for doses administered in the range of 0.03-0.18 mg kg(-1). Tail-flick latencies in rats administered D+M combinations were significantly greater than D alone (p<0.05).

CONCLUSIONS

A dose-related analgesic effect was demonstrated for D in the rat, which was enhanced by co-administration of M.

CLINICAL RELEVANCE

The combination of D+M administered IP to rats at doses of 0.12:20 and 0.09:15 mg kg(-1) was shown to be a good combination to provide sedation/analgesia with a duration of action greater than 60 minutes. The onset of sedation was rapid (1-3 minutes), and onset of profound analgesia was reached within 5-10 minutes.

Effects of intravenous small dose ketamine and midazolam on postoperative pain following knee arthroscopy

BACKGROUND

The aim of this randomized, double blind, controlled study was to assess the effect of intravenous coadministration of small dose midazolam with ketamine on postoperative pain and spinal block level.

METHODS

Sixty patients undergoing arthroscopic knee surgery under spinal anesthesia were randomized into three groups: Group I (saline control); group II (ketamine 0.15 mg/kg i.v.); and group III (ketamine 0.15 mg/kg + midazolam 0.01 mg/kg i.v.). Sedation scores, visual analogue scores, time to first postoperative analgesic, total meperidine consumption, patient satisfaction, sensory and motor block levels, and two segments regression times were assessed.

RESULTS

Sedation scores were significantly lower in group I when compared with groups II and III at 1, 3, 5, and 10 minutes after administration of the spinal anesthetic (P = 0.001). Sensory block was significantly higher in group III (P = 0.001) in comparison with group II. Two segment regression time was significantly longer in group II than group I, whereas no difference was found between groups II and III. Total meperidine consumption was significantly higher in group I (P = 0.001). Patient satisfaction was significantly higher in group III compared with group I (P = 0.001), but no difference was found between groups II and III (P = 0.3).

CONCLUSION

Ketamine improved the postoperative pain patient satisfaction, increased the maximal sensory level, and was associated with lower sedation scores in the first 15 minutes after administration. Group I was also associated with decreased total meperidine consumption and delayed the time to first recue analgesic administration. Coadministration of ketamine and midazolam did not provide any further benefit over ketamine alone.

Adjunctive analgesic therapy in veterinary medicine

Adjunctive analgesic therapies are interventions for pain that involve agents or techniques other than the traditional analgesics (opioids, nonsteroidal anti-inflammatory drugs, and local anesthetics). Adjunctive therapies may be pharmacologic or nonpharmacologic in nature. The focus of this article is on pharmacologic interventions with potential utility as adjunctive analgesics in veterinary medicine. Pharmacology of selected agents, including medetomidine, ketamine, amantadine, gabapentin, systemic lidocaine, and pamidronate, is discussed in addition to evidence for their safety and efficacy and guidelines for their use in veterinary patients.

Clinical pain management peri-operative scenarios

This article reinforces the clinical points of emphasis that have been stressed throughout this issue in a case scenario format. Common situations dealt with by physicians are examined to highlight the underlying physiology of the specific complaints and treatment interventions. The goal of this article is to present an evidenced-based review of pain management interventions in a format that allows for reader incorporation.

Peri-operative pain management

Surgery is a circumstance in which we know that we will cause pain. Although most of our perioperative pain management interventions are symptomatic, several strategies can reduce and even prevent pain in the perioperative setting. Because the physiologic mechanisms of postoperative pain are understood, it is possible to interrupt these mechanisms before the patient actually becomes symptomatic. This article reviews the literature and presents these strategies with the hope of implementation of the readers.

Recent advances in the pharmacological management of pain

Pain is an unpleasant sensation that originates from ongoing or impending tissue damage. Management of different types of pain (acute, postoperative, inflammatory, neuropathic or cancer) is the most frequent issue encountered by clinicians and pharmacological therapy is the first line of approach for the treatment of pain. This review presents and discusses recent clinical advances regarding both the improvements in delivery of analgesic drugs and improvements in the design of analgesic molecules. The new modalities of administration of analgesics used in the clinic are reviewed, including skin patches, oral and mucosal sprays, transdermal delivery systems and intranasal administration. New insights are then presented on standard drugs used to relieve pain, such as opioids (including tramadol), NSAIDs including selective cyclo-oxygenase-2 inhibitors, paracetamol (acetaminophen), local anaesthetics and adjuvant analgesics such as antidepressants, anticonvulsants (gabapentin and pregabalin), cannabinoids, ketamine and others (e.g. nefopam). Although the understanding of pain mechanisms has improved significantly recently, much more is yet to be discovered and awaited. Broadening of our knowledge is needed to improve basic and clinical research in this field in order to better alleviate pain in millions of people.