A strategy for conversion from subcutaneous to oral ketamine in cancer pain patients: effect of a 1:1 ratio

Ketamine use in critically ill patients: a narrative review

Ketamine is unique among anesthetics and analgesics. The drug is a rapid-acting general anesthetic that produces an anesthetic state characterized by profound analgesia, preserved pharyngeal-laryngeal reflexes, normal or slightly enhanced skeletal muscle tone, cardiovascular and respiratory stimulation, and occasionally a transient and minimal respiratory depression. Research has demonstrated the efficacy of its use on anesthesia, pain, palliative care, and intensive care. Recently, it has been used for postoperative and chronic pain, as an adjunct in psychotherapy, as a treatment for depression and posttraumatic stress disorder, as a procedural sedative, and as a treatment for respiratory and/or neurologic clinical conditions. Despite being a safe and widely used drug, many physicians, such as intensivists and those practicing in emergency care, are not aware of the current clinical applications of ketamine. The objective of this narrative literature review is to present the theoretical and practical aspects of clinical applications of ketamine in intensive care unit and emergency department settings.

Comeback of ketamine: resurfacing facts and dispelling myths

Initially known as CI-581, ketamine was first synthesized in 1962 as a replacement from phencyclidine. It has since been used as an anesthetic and analgesic. In addition, it has bronchodilating, sedative, and amnestic properties, preserving airway reflexes and sympathetic nervous system tone. Since the discovery of ketamine, it has been a major topic of discussion due to controversies regarding its usage in particular sets of patients. In the past 50 years, despite its potential benefits, it is not commonly used because of concerns of "emergence phenomenon," its use as a substance of abuse, and its systemic side effects. Since 2012, three World Health Organization reviews on ketamine have addressed its international control. Researchers have been studying this wonder drug for a decade worldwide. Many myths of ketamine regarding emergence phenomenon and its use in traumatic brain injury and open eye injury have been disproved in recent times. It is becoming popular in pre-hospital settings, critical care, emergency medicine, low-dose acute pain services, and adjuvant in regional anesthesia techniques. This review highlights the current consensus on the various applications of ketamine in the literature.

Iatrogenic Oral Ketamine Overdose in Palliative Care

Background: Optimal pain management in the palliative care setting often requires multiple pharmacological interventions including novel and off-label therapies. Ketamine is an anesthetic agent with increasing evidence supporting its use for pain. Through N-methyl-d-aspartate antagonism and activity at opioid receptors, it is an adjuvant to traditional analgesics with the benefit of being opioid sparing. Ketamine has a wide safety profile with limited reports of overdose. Little is published on supratherpeutic dosing in the pain setting. Objective: We report a case of a 41-year-old male with refractory nociceptive and neuropathic cancer-related pain. Conventional therapies were ineffective. Ketamine was initiated to reduce opioid burden and attenuate pain with good response. The patient received an iatrogenic overdose (10 times ordered dose) of the drug. Several self-limited physiologic and psychologic reactions were observed during subsequent monitoring. Design: This is a study and analysis of a patient with refractory nociceptive and neuropathic pain syndrome treated with ketamine who sustained an iatrogenic overdose of ketamine. Conclusions: Ketamine's use to treat pain is increasing along with its evidence of efficacy. Despite ketamine's wide safety profile, the medication is not without risk, especially in palliative care wherein patients are on multiple drugs with potentially severe interactions. Careful examination of the risks of overdose, especially of the various formulations of the drug, is needed.

Comparison of intraperitoneal bupivacaine, acetazolamide, and placebo on pain relief after laparoscopic cholecystectomy surgery: A clinical trial

Background: Given the importance of patients' pain after laparoscopic surgeries, this study was conducted to compare the effectiveness of intraperitoneal bupivacaine, acetazolamide, and placebo on pain relief after laparoscopic cholecystectomy surgery. Methods: Patients admitted to Rasool Akram hospital with physical status I or II, based on the American Society of Anesthesiologists (ASA) system, who were candidates for laparoscopic cholecystectomy surgery due to gallstones, were included in this study. Patients were divided into 3 groups (each group containing 20 patients) using block randomization with foursome blocks. Group 1 received bupivacaine, group 2 acetazolamide, and group 3 intravenous saline as placebo. After surgery, pain score was assessed by visual analogue scale, and shoulder pain and analgesic doses were also measured. The mentioned parameters were assessed at 1, 4, 8, 12, and 24 hours after surgery. Results: In this study, 60 patients were included in 3 groups. The mean pain recorded (VAS) at 1, 4, and 8 hours after surgery was not significantly different between acetazolamide and bupivacaine groups, but their score was significantly lower than the placebo group (p<0.05). However, the score recorded at 12 and 24 hours after surgery was not significantly different between the 3 groups (p>0.05). Mean of pain reliever (acetaminophen) injected to the patients when needed was not significantly different among the 3 intervention groups (p<0.05). The highest prevalence of shoulder pain (70%) belonged to the placebo group and the lowest (25%) to acetazolamide (p<0.05). Mean heart rate, systolic blood pressure, diastolic blood pressure, and the respiratory rate were not significantly different among intervention groups in 1, 4, 8, 12, and 24 hours after surgery (p>0.05). Conclusion: According to the results, acetazolamide and bupivacaine injection reduced pain in early hours after laparoscopy. However, pain intensity was not different between intervention groups and the control group after 12 hours, so re-prescription seems to be appropriate at this time. Acetazolamide injection significantly reduces shoulder pains after surgery.

Ketamine: Current applications in anesthesia, pain, and critical care

Ketamine was introduced commercially in 1970 with the manufacturer's description as a "rapidly acting, nonbarbiturate general anesthetic" and a suggestion that it would be useful for short procedures. With the help of its old unique pharmacological properties and newly found beneficial clinical properties, ketamine has survived the strong winds of time, and it currently has a wide variety of clinical applications. It's newly found neuroprotective, antiinflammatory and antitumor effects, and the finding of the usefulness of low dose ketamine regimens have helped to widen the clinical application profile of ketamine. The present article attempts to review the current useful applications of ketamine in anesthesia, pain and critical care. It is based on scientific evidence gathered from textbooks, journals, and electronic databases.

The effect of single-dose administration of dexamethasone on postoperative pain in patients undergoing laparoscopic cholecystectomy

Background:

Postoperative pain is considered as a reason of patient’s delay in discharge and disability aggravation. Therefore, multimodal approaches have been suggested in order to mitigate pain and decrease postoperative side effects.

Objectives:

The aim of this study was to evaluate analgesic effect of a single dose injection of dexamethasone on reducing postoperative pain in laparoscopic cholecystectomy.

Patients and Methods:

In this double-blind, prospective study, 122 patients aged 18-60 years old, whom were selected for laparoscopic cholecystectomy, were classified into two case and control groups, and 61 patients were included in each group. The case (D) group underwent general anesthesia and a single- dose intravenous injection of dexamethasone. The Control (C) group received general anesthesia and intravenous injection of normal saline. Total dose of consumed meperidine and pain intensity during first 24 hours were evaluated in both groups.

Results:

No significant difference existed between two groups regarding age, sex, weight and operation time. Pain intensity in group D was significantly less than group C (P < 0.01) after two, six and 12 hoursof surgery. No significant difference existed in pain intensity between two groups at the beginning of and 24 hours after the surgery (P > 0.05). Meperidine consumption in group D was significantly less than group C (P < 0.05).

Conclusions:

Findings of present study showed that single dose of intravenous dexamethasone, led to less pain intensity and amounts of meperidine consumption, in comparison with placebo.

Analgesic effect of low dose subcutaneous ketamine administration before and after cesarean section

BACKGROUND

Pain is considered as an importantissue after cesarean section. Multimodal approach to post cesarean pain management may not only enhance analgesia but also reduce side effects after the surgery.

OBJECTIVES

This study was aimed to evaluate the clinical efficacy of subcutaneous injection of low dose ketamine at the incision site to reduce cesarean section pain.

PATIENTS AND METHODS

Sixty patients, aged between 18 and 25 years old, scheduled for elective cesarean section, were enrolled to this double-blind randomized controlled trial study. Patients were divided into three groups of 20 patients each group one (k-pre) received 0.5 mg/kg ketamine before skin incision and normal saline after skin closure, group two (k-post) received normal saline before skin incision and 0.5 mg/kg ketamine after skin closure and group three (C) received normal saline before skin incision and after skin closure; subcutaneously at the incision site. The first analgesic request, the amount of analgesic and the pain intensity were evaluated for 24 hours.

RESULTS

The first time analgesic requested was longer and the amount of analgesic used during the first 24 hours was significantly lower in groups K-pre and K-post compared with group C (P < 0.05). Pain intensity was significantly lower at 2, 4, 6 and 12 hours in groups K-pre and K-post compared with group C (P < 0.05). Nevertheless, pain intensity was not significantly different at 18 and 24 hours in group C (P > 0.05). The first requested time, total used amount of analgesicand pain intensity were not meaningfully different in K-pre and K-post groups (P > 0.05).

CONCLUSIONS

Patients who were given ketamine before or after cesarean section subcutaneously at incision site had lower pain intensity and less analgesic consumption than patients who were given placebo.

Ketamine for pain in adults and children with cancer: a systematic review and synthesis of the literature

OBJECTIVE

Chronic cancer pain is often refractory and difficult to treat. Ketamine is a medication with evidence of efficacy in the treatment of chronic pain.

DESIGN

This article presents a synthesis of the data on ketamine for refractory cancer pain in adults and children.

RESULTS

There are five randomized, double-blind, controlled trials of ketamine use in cancer pain that demonstrate improvement in pain for some patients. There are six prospective, uncontrolled trials in cancer pain that also demonstrate improvement in pain scores for some patients. There are no randomized, controlled trials in children with cancer pain, although there are a few studies reflecting improved pain control with ketamine for children with cancer pain. Adverse events for adults on ketamine are most commonly somnolence, feelings of insobriety, nausea/vomiting, hallucinations, depersonalization/derealization, and drowsiness. However, when ketamine is combined with benzodiazepines, feelings of insobriety, hallucinations, and depersonalization/derealization are not reported. Children on ketamine have had few reported adverse effects, which include sedation, anorexia, urinary retention, and myoclonic movements. Recommended ketamine infusion dosages are from 0.05 to 0.5 mg/kg/h (intravenous or subcutaneous). Recommended oral dosages of ketamine are 0.2-0.5 mg/kg/dose two to three times daily with a maximum of 50 mg/dose three times daily.

CONCLUSIONS

Despite limitations in the breadth and depth of data available, there is evidence that ketamine may be a viable option for treatment-refractory cancer pain.

Preincisional administration of intravenous or subcutaneous infiltration of low-dose ketamine suppresses postoperative pain after appendectomy

BACKGROUND

Ketamine, an N-methyl-D-aspartate receptor antagonist, can suppress hyperalgesia and allodynia. The purpose of the present study was to evaluate the clinical efficacy of preincisional intravenous or subcutaneous infiltration of ketamine for postoperative pain relief after appendectomy.

METHODS

Ninety patients, aged 18-60 years, scheduled for appendectomy was enrolled in this study. Patients were divided into three groups of 30 each and received subcutaneous infiltration of ketamine 0.5 mg/kg (KS), intravenous ketamine 0.5 mg/kg (KI), or subcutaneous infiltration of normal saline 3 mL (C) before surgery. Visual analog scale (VAS) values and analgesic consumption were evaluated for 24 hours after surgery.

RESULTS

VAS scores were significantly lower at the time of arrival in the recovery room, and at 10, 20, and 30 minutes thereafter in group KI and group KS compared with group C (P < 0.05). VAS scores were not significantly different between group KI and group KS at these intervals. Postoperative VAS scores were significantly lower at 6, 12, 18, and 24 hours in group KI compared with group C (P < 0.05). In group KS, the postoperative VAS score was significantly lower at 6 hours (P < 0.05). VAS scores were significantly lower at 12, 18, and 24 hours after surgery in group KI compared with group KS (P < 0.05).

CONCLUSION

A 0.5 mg/kg dose of ketamine given at approximately 15 minutes before surgery by the intravenous route provided analgesia for 24 hours after surgery in patients undergoing appendectomy.