Low-dose Intravenous Ketamine Research Articles

Bilateral superficial cervical plexus block with or without low-dose intravenous ketamine analgesia: effective, simple, safe, and cheap alternative to conventional general anesthesia for selected neck surgeries

BackgroundGeneral anesthesia is commonly used for surgery in the neck region. Superficial cervical plexus block is adequate to produce anesthesia in the anterior and anterolateral aspects of the neck. Our aim was to observe the effectiveness of bilateral cervical plexus block for surgery in this region of the neck.MethodsA total of 136 neck surgery cases were enrolled in this prospective uncontrolled study. All patients were administered ropivacaine 0.5% as a bilateral cervical plexus block. The incision line was infiltrated with lignocaine 1% and adrenaline 1:100,000. For thyroglossal cyst and thyroglossal fistula, an additional 1.5 mL of LA solution was deposited over the hyoid bone on both sides of the midline. Any anesthetic inadequacy was corrected using ketamine 25 mg intravenously and repeated if necessary.ResultsOf 37 patients with thyroglossal cyst, the block was sufficient in 36 patients, and one patient required ketamine. Block was adequate in 23 of 24 patients with thyroglossal fistula, and one patient required ketamine. Among the branchial cyst and branchial fistula cases, six of 16 patients required ketamine supplementation. Of three thyroidectomy patients, one required ketamine supplementation, and one was converted to conventional general anesthesia. For lymph node excision and lymph node biopsy patients, LA block was sufficient in all 31 cases. In the last group, one of 25 patients required ketamine supplementation.ConclusionThe overall success of bilateral cervical plexus block as a sole method of anesthesia in these selected neck surgeries was 91.9% and with low-dose ketamine supplementation it approached more than 99%. However, cervical plexus block was not a good method of anesthesia for thyroid surgery in this study. For the remainder of cases, bilateral cervical plexus block alone or in conjunction with ketamine appeared to be a cheap, safe, and effective alternative to conventional general anesthesia.

The effect of low-dose intravenous ketamine on continuous intercostal analgesia following thoracotomy

Ketamine, a noncompetitive N-methyl-d-aspartate antagonist, provides analgesia and prevents chronic pain following thoracotomy. The study was aimed to assess the effect of intravenous low-dose ketamine on continuous intercostal nerve block analgesia following thoracotomy. The study was a prospective, randomized, double-blinded, and placebo-controlled clinical study, performed in a single university hospital. Sixty patients, undergoing elective lobectomy through an open posterolateral thoracotomy, were included. For postoperative pain, all patients received a continuous intercostal nerve block with bupivacaine plus intravenous paracetamol and ketoprofen. In addition, patients were randomized to have intravenous ketamine (0.1 mg/kg as a preincisional bolus followed by a continuous infusion of 0.05 mg/kg/h) in group 1 or intravenous placebo in group 2. Patients reporting a visual analog scale pain score at rest ≥40 mm received intravenous morphine sulfate as rescue analgesia. The following parameters were assessed every 6 hours for 3 postoperative days: Visual analog scale pain scores at rest and during coughing, requirement of rescue analgesia with morphine, Ramsay sedation scores and psychomimetic adverse effects. Both the groups were statistically comparable regarding visual analog scale pain scores at rest (P=0.75) and during coughing (P=0.70), number of morphine deliveries (P=0.17), cumulative dose of rescue morphine (P=0.2), sedation scores (P=0.4), and psychomimetic adverse effects (P=0.09). Intravenous low-dose ketamine, when combined with continuous intercostal nerve block, did not decrease acute pain scores and supplemental morphine consumption following thoracotomy.

Intra- and Postoperative Very Low Dose Intravenous Ketamine Infusion Does Not Increase Pain Relief after Major Spine Surgery in Patients with Preoperative Narcotic Analgesic Intake

This study aims to demonstrate the analgesic efficacy and opioid-sparing effect of low dose ketamine in patients with preoperative narcotic intake undergoing major spine surgery. The study used a prospective, randomized, double-blinded, and placebo-controlled clinical trial. We evaluated the analgesic efficacy and safety of low dose IV ketamine infusion after major spine surgery in patients with preoperative narcotic analgesic intake. Ketamine group received IV ketamine infusion (2 µg/kg/min) and saline group received saline intraoperatively and the first 24 hours postoperatively. In addition, all patients received IV patient-controlled hydromorphone and epidural bupivacaine. Pain scores, narcotic requirement, and side effects were compared between the groups for 48 hours postoperatively. Thirty patients completed the study (N = 15 in each group). No difference in pain scores at rest and movement was noted between the groups (P > 0.05). Patients in ketamine group received 40.42 ± 32.86 mg IV hydromorphone at 48 hours compared with 38.24 ± 26.19 mg in saline group (P = 0.84). Central nervous system side effects were observed in five (33%) ketamine group patients compared with nine (60%) in saline group (P = 0.29). The addition of IV very low dose ketamine infusion regimen did not improve postoperative analgesia. Side effects were not increased with low dose ketamine.

Rapid-acting antidepressant strategies: mechanisms of action

Current antidepressants are ineffective in many depressed patients. Thus there is an urgent need to develop treatment strategies which have significantly faster response, can be sustained and have minimal side-effects. This paper reviews clinical data, potential biomarkers, mechanisms of action and future research directions for two proven strategies that produce marked improvement in severe depressive symptoms within 48 h, ketamine and sleep deprivation therapy (SDT). These treatments provide unequivocal evidence that the depressive process can be rapidly reversed in a subgroup of patients. Seventeen ketamine studies in over 150 patients showed a rapid response. Low-dose intravenous ketamine produced mild psychotomimetic effects but response has not been effectively sustained. SDT has been investigated in over 60 studies with a 40-60% response rate within 48 h. Although SDT is often used in Europe to initiate a rapid response, it is less utilized within the USA, in part, because it has a short duration when administered alone. We review data concerning chronotherapeutic strategies of bright-light therapy (BLT) and sleep-phase advance (SPA) which successfully sustain the antidepressant efficacy of SDT. Evidence is further discussed that a significant group of mood disorders have abnormal circadian rhythms which are known to be controlled by clock genes. It is hypothesized that chronotherapeutic manipulations can reset clock genes and thus, abnormalities in circadian rhythms. Further findings are reviewed that ketamine, in addition to its role as an NMDA antagonist, can also alter circadian rhythms. Thus, ketamine may share a critical mechanism with SDT.

Effects of Midazolam/Low-Dose Ketamine Conscious Intravenous Sedation on Pain, Swelling, and Trismus After Surgical Extraction of Third Molars

To assess the clinical efficacy of midazolam plus low-dose ketamine conscious intravenous sedation on relief from or prevention of postoperative pain, swelling, and trismus after the surgical extraction of third molars. Patients admitted for surgical extraction of mandibular third molars (n = 50) were included. All patients received an initial dose of 0.03 mg/kg intravenous midazolam; then patients in the midazolam-placebo (MP) group received 2 mL of a placebo IV, while patients in the midazolam-ketamine (MK) group received 2 mL of a ketamine + saline combination (0.3 mg/kg ketamine + saline) IV. Facial swelling on postoperative days was significantly lower in the MK group than in the MP group (P = .001). Mouth opening on postoperative days was significantly greater in the MK group than in the MP group (P = .001). Pain scores measured on a visual analog scale at 4, 12, and 24 hours after surgery were significantly higher in the MP group than in the MK group (P = .001). Conscious intravenous sedation with midazolam/low-dose ketamine during surgical extraction of third molars can provide the patient with a comfortable procedure and good postoperative analgesia, with less swelling and significantly less trismus. Intravenous low-dose ketamine may be safe and effective in reducing postoperative pain.

Pre-Incisional Intravenous Low-Dose Ketamine Does Not Cause Pre- Emptive Analgesic Effect Following Caesarean Section under Spinal Anaesthesia

Background: Adequate postoperative pain relief is one of the commonest challenges faced by women who deliver by caesarean section. Aim: This study was aimed at finding out the effect of pre-incisional administration of low dose intravenous ketamine on the post-operative analgesia demand time. Patients and Methods: Following approval from the Hospital’s Ethical Committee, a prospective, randomised double-blind study was carried out to evaluate the pre-emptive effect of low-dose ketamine on women undergoing elective caesarean section under plain bupivacaine/fentanyl spinal anaesthesia. Results: Eighty women completed (83.33%) the study. The results were comparable in both groups for maternal age, weight, height, gestational age and parity. There was no statistical difference in the patient characteristics between the two groups under study. The mean time taken to achieve a maximal sensory level was 9.3±0.91 mins in Group-A and in Group-B 8.35±1.49 mins, p=0.260. The regression time to two segments was also the same in the two groups of women. The mean in the Group-A was 28.1±1.52 mins while the Group-B had 27.6±2.10 mins, p=0.161. The time to first analgesic request in the Ketamine Group was 193.44±26.53 mins while that for the Placebo group was 140.14±22.34 mins. The difference in the duration was statistically significant, p=0.0001. Conclusion: It is concluded that the pre-incisional administration of low-dose intravenous ketamine only demonstrated a delayed time to first analgesic request in the women who had plain bupivacaine/fentanyl spinal anaesthesia and not a pre-emptive analgesic effect.

The effect of intravenous low dose ketamine for reducing postoperative sore throat

BackgroundThis study was performed to evaluate the effectiveness of intravenous low dose ketamine for reducing the incidence and severity of postoperative sore throat (POST).MethodsThis was a prospective, randomized, double-blind clinical trial. The study population consisted of 70 patients between 20 and 70 years old who were classified as American Society of Anesthesiologists I-II and were scheduled for elective laparoscopic cholecystectomy. The patients were divided randomly into two groups. Patients in the ketamine group received an intravenous injection of 0.5 mg/kg of ketamine just before induction, followed by 10 µg/kg/min throughout the operation. Patients in the control group received intravenous saline instead of ketamine. The patients were interviewed 1, 6, and 24 h after the operation. The incidence and severity of POST were recorded.ResultsNo significant differences in the incidence and severity of POST during the 24 h after the operation were found between the two groups (21/31 in the ketamine group vs. 26/34 in the control group, P = 0.398).ConclusionsIntravenous injection of low dose ketamine was not effective for reducing POST.

Postoperative analgesia and early rehabilitation after total knee replacement: A comparison of continuous low-dose intravenous ketamine versus nefopam

The effects of nefopam and ketamine on pain control and rehabilitation after total knee replacement were compared in a prospective, double blinded study. Seventy-five patients were randomly assigned to receive a 0.2 mg kg −1 bolus of nefopam or ketamine, followed by a 120 μg kg −1 h −1 continuous infusion until the end of surgery, and 60 μg kg −1 h −1 until the second postoperative day, or an equal volume of saline considered as placebo. Pain scores measured on a visual analog scale at rest and on mobilization, and patient-controlled intravenous morphine consumption, were assessed during 48 h. We measured the maximal knee flexion on the third postoperative day, and the delay to obtain a 90° flexion. Ketamine and nefopam reduced morphine consumption ( p < 0.0001). Pain scores, were lower at rest and on mobilization in the ketamine group compared to the two other groups at all times of measurement. Pain score were lower in patients receiving nefopam compared to placebo, on arrival in the recovery room and at 2 h. Ketamine improved knee flexion on post operative day 3 (59° [33–63] vs. 50° [47–55] and 50° [44–55] in ketamine, placebo and nefopam groups, respectively, p < 0.0002) and decreased the delay to flex the knee at 90° (9.1 ± 4.2 vs. 12.3 ± 4.0 days, in ketamine and placebo groups, respectively, p = 0.01). Ketamine produces opioid-sparing, decreases pain intensity, and improves mobilization after total knee replacement. Nefopam achieves less significant results in that circumstances.

Prévenir les hallucinations aiguës associées à la perfusion intraveineuse continue de kétamine

Continuous low dose infusion of intravenous ketamine for postoperative analgesia was often associated with frightening acute psychodysleptic experiences in our patients. We hypothesized they were due to boluses of ketamine accumulated in the infusion line. We evaluated on two successive groups the impact of perfusion line modifications on psychodysleptic side effects occurrence. We compared a reference historic group (in which ketamine line was connected to perfusion line) to a second prospective group (in which ketamine line was connected to the venous catheter via an unidirectional valve). Psychodysleptic experiences occurrence decreased from 4 patients of 26 (15%) to 2 of 116 (2%, p = 0.01). Moreover, these experiences were no longer associated with severe anxious symptoms like near death experiences. An unidirectional valve must be considered to limit the occurrence of low dose intravenous ketamine infusion associated psychedelic side effects, during postoperative analgesia.

Low-Dose Ketamine in Addition to Propofol for Procedural Sedation and Analgesia in the Emergency Department

To evaluate the efficacy and safety of low-dose intravenous ketamine in addition to intravenous propofol for procedural sedation and analgesia in the emergency department (ED). Articles were identified using PubMed (1949-February 2007), MEDLINE (1966-February 2007), EMBASE (1980-February 2007), BioMed Central (to February 2007), the Cochrane Library (to February 2007), International Pharmaceutical Abstracts, and Google Scholar (until February 2007). Reference citations from retrieved publications were also reviewed. Search terms included ketamine, propofol, ketamine-propofol, ketofol, combination, sedation, procedural sedation, conscious sedation, and emergency department. All articles on prospective procedural sedation that were published or translated into English and that compared combination ketamine-propofol with an appropriate comparator group were included. Clinically relevant safety endpoints included the frequency of significant hemodynamic and respiratory compromise warranting medical intervention, nausea, vomiting, and emergence reactions. Time until hospital discharge criteria were met and patient satisfaction scores were efficacy endpoints of interest. Of the 11 trials included in this review, most had small sample sizes and were conducted in non-ED settings. The ketamine-propofol combination demonstrated no additional efficacy over propofol in terms of time to discharge. Although fewer patients given the ketamine-propofol combination experienced significant hemodynamic and respiratory compromise, need for active interventions, including fluid or vasopressor administration, supplemental oxygen, or assisted ventilation did not differ between groups. Patients who received higher doses of adjuvant ketamine reported an increased incidence of nausea, vomiting, and emergence reactions following the procedure. Few studies reported patient satisfaction scores postprocedure, and effect of ketaminepropofol on time-to-discharge criteria met was inconclusive. At this time, insufficient clinical evidence exists to recommend the routine use of low-dose ketamine with propofol for procedural sedation in the ED setting.

Premedication with intravenous low-dose ketamine suppresses fentanyl-induced cough

Study Objective To evaluate the effect of low-dose ketamine on fentanyl-induced cough. Design Prospective, randomized, double-blind, placebo-controlled clinical trial. Setting Medical center hospital. Patients 360 ASA physical status I-II patients aged 18 to 65 years, weighing between 40 and 80 kg, and scheduled for elective surgery during general anesthesia. Interventions and Measurements Patients were randomly assigned to receive either ketamine 0.15 mg/kg or placebo (equal volume of 0.9% saline) given intravenously over 10 seconds, one minute before administration of fentanyl (1.5 μg/kg IV, injected within 5 seconds), during induction of general anesthesia. Any episode of cough was classified as coughing and the onset time of cough (the time of the first episode of cough) was observed for one minute after fentanyl administration by a blinded observer. Severity of coughing was graded based on the number of episodes of coughing (mild, 1-2; moderate, 3-5; and severe, >5). Blood pressure, heart rate, and pulse oximetry oxygen saturation (Sp o 2) were recorded before giving ketamine or 0.9% saline and 1 minute after fentanyl injections. Main Results After the intravenous injection of fentanyl bolus, patients in the placebo group showed significantly higher frequency cough than those in the ketamine pretreatment group (21.6% vs 7.2%, P < 0.05), and onset time of the ketamine group was significantly longer than that of the control group (20 ± 8 vs 15 ± 10 seconds, P < 0.01). However, no difference in cough severity was observed between the two groups. Conclusion Low-dose ketamine (0.15 mg/kg IV) effectively reduces fentanyl-induced cough and delays the onset time of cough.

Low-Dose Intravenous Ketamine: An Effective Adjunct to Conventional Deep Conscious Sedation

Gradually over time, deep conscious sedation has become highly refined for outpatient surgery. Our technique is safe and provides a favorable working environment for the surgeon. Our patients have rapid recovery with minimal side effects from the drugs.

The persisting analgesic effect of low-dose intravenous ketamine after spinal anaesthesia for Caesarean section

To compare the analgesic effects of intrathecal fentanyl and low-dose intravenous ketamine as adjuvants to intrathecal bupivacaine for Caesarean section. Ninety elective Caesarean section patients were randomized into three groups. Spinal anaesthesia was performed with 15 mg hyperbaric bupivacaine in all groups. Ketamine (0.15 mg kg(-1)) or an equal volume of normal saline was given intravenously immediately after initiating spinal anaesthesia in the ketamine and control group, respectively. In the fentanyl group, 10 microg fentanyl was added to the intrathecal bupivacaine. Arterial pressures, heart rate values, adverse effects, the time of first request for postoperative analgesia, visual analogue pain scores, total analgesic consumptions at 24 and 48 h were recorded in all patients. The time to first request for analgesia was significantly longer in the ketamine (197 min) and fentanyl (165 min) groups compared to the control group (144 min). Postoperative pain scores were significantly lower in the ketamine group than in both other groups. Although the analgesic requirements during first 24 h were significantly lower in the ketamine group, there was no significant difference between the groups during the following 24 h. Intravenous low-dose ketamine combined with intrathecal bupivacaine for Caesarean section provides longer postoperative analgesia and lower postoperative analgesic consumption than bupivacaine alone suggesting a pre-emptive effect.

The Effects of the Intravenous Continuous Infusion of Low-dose Ketamine on Postoperative Pain after Total Intravenous Anesthesia

Background: Ketamine, a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, may prevent central sensitization and result in preemptive analgesia when administered before surgically induced trauma. The goal of this study was to determine whether intravenous low dose ketamine would reduce postoperative pain and cumulative analgesic requirements after total intravenous anesthesia (TIVA) with propofol and fentanyl. Methods: The thirty-four patients undergoing total abdominal hysterectomy were randomly allocated to according to anesthetic agent to a propofol-fentanyl- (60%)- (40%) group (group PFN) or a propofol-fentanyl-ketamine- (40%) group (group PFK); 0.3 mg/kg of ketamine initially during induction followed by a continous infusion at 0.15 mg/kg/h. Propofol and fentanyl were continuously administered using target controlled infusion (TCI). Intravenous patient-controlled analgesia (IV-PCA) using a fentanyl-ketorolac mixture was started in all patients after full recovery in a postanesthetic care unit (PACU). Verbal numerial scale (VNS) pain scores, cumulative total analgesic consumptions, and side effects were recorded immediately before and at 1, 3, 6, 12, 24, and 48 h after IV PCA. Results: No significant intergroup differences were seen in the VNS pain scores and in side effects during entire study period. But, patients in the PFK group had significantly lower total analgesic consumptions at 48 h after IV PCA. No significant differences were observed between the two groups in terms of side effects. Conclusions: Intravenous low dose ketamine during TIVA with propofol and fentanyl did not reduce postoperative pain scores, but did reduce total analgesic requirement at 48 h after IV PCA.

Paradoxical reaction following intravenous midazolam premedication in pediatric patients – a randomized placebo controlled trial of ketamine for rapid tranquilization

Paradoxical reactions to benzodiazepines include restlessness, violent behavior, physical assault, act of self-injury and need for restraints. These may occur at variable times after administration. This study was designed to determine the incidence of paradoxical reactions following intravenous midazolam premedication in pediatric patients and to compare the efficacy of extra doses of midazolam with low-dose intravenous ketamine to rapidly tranquillize them. A total of 706 ASA I, II children scheduled for elective surgery were given intravenous midazolam premedication. Children who developed a paradoxical reaction were randomly divided into three equal groups to receive: (i) extra midazolam, (ii) ketamine, or (iii) placebo as the test drug for treatment of paradoxical reaction. Ease of rapid tranquillization and need for a rescue tranquillizer (i.e. ketamine; irrespective of patient group) were compared among the three groups. Twenty-four (3.4%) children developed paradoxical reaction after midazolam premedication. Those who received ketamine as the test drug responded rapidly to ketamine. But the responses of the other two groups to their test drug were poor and the majority of them required ketamine as rescue tranquillizer (six in midazolam, seven in placebo, but no patient in the ketamine group; P < 0.05). The results of this study demonstrate that ketamine is an effective drug for the treatment of paradoxical reaction following intravenous midazolam premedication. The exact mechanisms of these reactions and how it is aborted by ketamine are not clear.

A Study on the Preemptive Analgesic Effect of Low Dose Intravenous Ketamine and Combined Ketamine-Clonidine

Background: The purpose of this study was to evaluate the preemptive analgesic effect of a single intravenous infusion of low dose ketamine-clonidine. We compared the placebo with low dose ketamine and low dose ketamine-clonidine in patients undergoing an appendectomy. Methods: Sixty ASA class 1 or 2 patients who received general anesthesia for an appendectomy were allocated randomly to three groups. Group 1 received intravenous normal saline 6 ml and group 2 received ketamine 0.15 mg/kg in normal saline 6 ml and group 3 received ketamine 0.15 mg/kg and clonidine 1/kg in normal saline 6 ml 5 minutes before surgical incision. In the recovery room postoperative analgesia was assessed by the verbal numerical rating scale (VNRS) at 0 min, 15 min, 30 min, 60 min, 90 min and 120 min. Vital signs, sedation score and side effects were also checked. For postoperative analgesia, morphine 2 mg was given intravenously whenever a patient complained of pain, or the VNRS score was above 7. Results: There were no intergroup differences of individual morphine requirements for postoperative pain control among the three groups. VNRS score, blood pressure, heart rate, sedation score and side effects were not significantly different among the three groups. Conclusions: A single low dose of ketamine-clonidine may not produce a postoperative analgesic effect in the recovery room, and a single low dose of ketamine also may not produce the preemptive effect for at least 2 hours.

When Is Preemptive Analgesia Truly Preemptive?

n Reply:—For the study of preemptive analgesia, preincisional and postincisional groups or preincisional and post–skin-closure groups are sometimes compared. Nociception at skin incision (skin pain) may have a strong impact on central sensitization, as shown by Katz et al. 1However, nociception may also occur at any time during surgery, and intrasurgical nociception is also considered an important sensitizing factor (deep pain, including visceral pain). Therefore, postincisional analgesia may reduce central sensitization in control subjects. On the other hand, an analgesic administered after skin closure produces its effect after surgery, directly reducing postsurgical pain in control subjects. These observations suggest that postincisional as well as post–skin-closure groups are inadequate controls for studying preemptive analgesia. Consequently, we believed that eliminating the aftereffect of morphine in the preemptive group could be an appropriate control.Naloxone is widely known to rapidly antagonize the effect of morphine, 2and this has been clearly evidenced in clinical practice. Opioid receptors are expressed on spinal cord neurons. Regardless of administration routes, intravenous or epidural, morphine binds to spinal opioid receptors, and naloxone displaces morphine from its binding sites, also irrespective of the administration route used.In a recent investigation, the half-life of intrathecally administered morphine was shown to be approximately 2 h. Approximately 60% of the intra–spinal cord morphine was cleared into the systemic circulation. 3In our study, naloxone administered at the end of surgery may have efficiently accelerated the clearance of morphine and shortened its half-life. Furthermore, our dosage of epidural morphine was smaller than that of intravenous morphine. 4The onset of naloxone’s antagonistic effect is rapid, and the duration of the effect is short. 2Therefore, the aftereffect of morphine might be eliminated earlier, suggesting that postsurgical pain control might be achieved smoothly and that the aftereffect of morphine might be negligible at the first observation (6 h).In our study, 4a statistically significant difference between the epidural morphine and combination (epidural morphine plus intravenous ketamine) groups was observed at every time point measured (6, 12, 24, and 48 h). In contrast, a significant difference between the epidural morphine and control groups was noted only at 24 and 48 h. The significant reduction in pain intensity with epidural morphine may be due to its preemptive effect (although not definitive) rather than to its aftereffect because morphine’s aftereffect must be evident at earlier time points (i.e. , 6 and 12 h).Ketamine binds to N -methyl-d-aspartate receptors and blocks nociceptive impulses. As stated previously, morphine binds to opioid receptors and also blocks primary afferent nociception. We used the word blockade for nociceptive blockade. As pointed out by Sarantopoulos and Fassoulaki, blockade of N -methyl-d-aspartate receptors and stimulation of opioid receptors (dual blockade of nociception) might potentiate the preemptive analgesic effect, as mentioned in our article. 4On the other hand, in gastrectomy, by total nociceptive blockade (T4–L1) over the surgical area (20 ml mepivacaine, 2%, at 60-min intervals was used intermittently; blockade was verified by pin-prick test before general anesthesia), most primary afferents to the spinal cord were intercepted. However, definitive preemptive analgesia was not attained. This fact also suggests the vagal nociception in gastrectomy. However, definitive preemptive analgesia was also attained by concomitant intravenous low-dose ketamine (unpublished data).Each group in our study received the same premedication and anesthesia. Therefore, premedicated drugs or anesthetics, including nitrous oxide, affected all groups, including the control group, equivalently. Nitrous oxide might have had an effect on nociception. However, the effect of nitrous oxide is small 5and may be negligible because in clinical anesthesia for surgery, analgesic intervention, such as analgesia with morphine or fentanyl, or epidural block, is usually required to avoid intrasurgical reaction to nociception. Thus, central sensitization is established during anesthesia with nitrous oxide.

A pilot study using low-dose intravenous ketamine as an analgesic for acute pain in adults

A pilot study using low-dose intravenous ketamine as an analgesic for acute pain in adults

Low-Dose Ketamine in the Management of Opioid Nonresponsive Terminal Cancer Pain

Two patients with far-advanced cancer, near death, who were experiencing excruciating and intractable pain that was poorly responsive to rapidly escalating doses of morphine and hydromorphone were treated with low-dose intravenous ketamine (0.1–0.2 mg/kg). This intervention eliminated the need for any further opioid use, providing profound analgesia and a sense of calm during the last hours and days of these patients’ lives. These case reports add to the small but growing body of clinical literature suggesting that ketamine may have a significant place in the care of patients with pain that is poorly responsive to opioids, or who experience dose-limiting adverse effects, near the end of life. This is an important matter to disseminate in order to reassure the public that we do have the tools necessary to keep the promise that no one need die with uncontrolled pain. This therapeutic approach may also serve to reassure concerned physicians that their efforts to assure pain relief may not be misconstrued as hastening death.

A double-blind comparison of low-dose intravenous ketamine and methohexital in adults

Two ultralight general anesthetic techniques, one using low-dose ketamine and the other using methohexital as the primary anesthetic agent, were compared for efficacy, safety, and psychomotor recovery in a double-blind fashion for use during third molar surgery. Low-dose intravenous ketamine as the primary anesthetic following premedication with fentanyl and midazolam, and in conjuction with nitrous oxide, appeared to produce less hypoxia, hypercarbia, and apnea than when methohexital was used. No significant differences were noted in heart rate or blood pressure between the techniques. The ketamine technique was universally preferred by the surgeons and anesthesiologists because of superior patient cooperation and airway management. No unpleasant psychomimetic side effects of significance were noted with the use of ketamine. Postoperative recovery took slightly longer in the ketamine group, with patients being judged fit for discharge approximately 10 to 15 minutes later than the patients who received methohexital.