Does ketamine have preemptive effects in women undergoing abdominal hysterectomy procedures? Postoperative analgesia with i.v. patient-controlled morphine: effect of adding ketamine. Can ketamine potentiate the analgesic effect of epidural morphine, preincisional or postincisional administration? PCA ketamine and morphine after abdominal hysterectomy. Intraoperative small-dose ketamine enhances analgesia after outpatient knee arthroscopy. Effect of the addition of ketamine to morphine in patient-controlled analgesia. Small-dose S(+)-ketamine reduces postoperative pain when applied with ropivacaine in epidural anesthesia for total knee arthroplasty. Small-dose ketamine enhances morphine-induced analgesia after outpatient surgery. Epidural ketamine reduces post-operative epidural PCA consumption of fentanyl/bupivacaine. Postoperative pain management with intravenous patient-controlled morphine: comparison of the effect of adding magnesium or ketamine. [Lack of pre-emptive analgesic effect of low-dose ketamine in postoperative patients. A prospective, randomised double-blind study]. Preincisional intravenous low-dose ketamine and local infiltration with ropivacaine reduces postoperative pain after laparoscopic cholecystectomy. The benefits of intraoperative small-dose ketamine on postoperative pain after anterior cruciate ligament repair. Mapping of punctuate hyperalgesia around a surgical incision demonstrates that ketamine is a powerful suppressor of central sensitization to pain following surgery. Preoperative ketamine improves postoperative analgesia after gynecologic laparoscopic surgery. The effects of small-dose ketamine on morphine consumption in surgical intensive care unit patients after major abdominal surgery. 'Balanced analgesia' in the perioperative period: is there a place for ketamine? Intraoperative intravenous ketamine in combination with epidural analgesia: postoperative analgesia after renal surgery. Lack of pre-emptive analgesic effect of (R)-ketamine in laparoscopic cholecystectomy. Improvement of pain treatment after major abdominal surgery by intravenous S+-ketamine. Comparison of postoperative analgesic effects of preemptively used epidural ketamine and neostigmine. A randomised, controlled study of peri-operative low dose s(+)-ketamine in combination with postoperative patient-controlled s(+)-ketamine and morphine after radical prostatectomy. Analgesic effects and pharmacokinetics of a low dose of ketamine preoperatively administered epidurally or intravenously. Adding ketamine in a multimodal patient-controlled epidural regimen reduces postoperative pain and analgesic consumption. Perioperative small-dose S(+)-ketamine has no incremental beneficial effects on postoperative pain when standard-practice opioid infusions are used. Preemptive analgesia by intravenous low-dose ketamine and epidural morphine in gastrectomy: a randomized double-blind study. Comparison of morphine and morphine with ketamine for postoperative analgesia. Preoperative epidural ketamine in combination with morphine does not have a clinically relevant intra- and postoperative opioid-sparing effect. Evaluation of the safety and efficacy of epidural ketamine combined with morphine for postoperative analgesia after major upper abdominal surgery. Effect of i.v. ketamine in combination with epidural bupivacaine or epidural morphine on postoperative pain and wound tenderness after renal surgery. Supplementing desflurane-remifentanil anesthesia with small-dose ketamine reduces perioperative opioid analgesic requirements.
Ketamine may produce "preemptive" analgesia when administered before surgically induced trauma. Therefore, we hypothesized that pre- versus postincisional administration of ketamine would improve pain control after abdominal hysterectomy procedures. Eighty-nine patients were randomly assigned to one of three treatment groups according to a placebo-controlled, double-blinded protocol: Group 1 (placebo) received saline 0.04 mL/kg IV immediately before and after surgery; Group 2 (preincision), received ketamine 0.4 mg/kg IV before skin incision and saline at the end of the operation; and Group 3 (postincision), received saline before skin incision, and ketamine 0.4 mg/kg IV was given after skin closure. The general anesthetic technique was standardized in all three treatment groups. During the first postoperative hour, Group 3 experienced significantly less pain than Groups 1 and 2, as assessed by using both visual analog and verbal rating scales. There were no significant differences between Groups 1 and 2 with respect to pain scores, postoperative opioid analgesic requirements, and incidence of postoperative nausea and vomiting. We conclude that a single dose of ketamine 0.4 mg/kg IV fails to produce preemptive analgesic effects. Implications: Even though ketamine 0.4 mg/kg IV has short-lasting acute analgesic effects, it failed to produce a preemptive effect when given before abdominal hysterectomy procedures. We have studied the effect of adding ketamine to i.v. morphine patient-controlled analgesia (PCA) for the treatment of pain after laparotomy. Thirty patients were allocated randomly to receive PCA with saline or ketamine in a double-blind, randomized study. Analgesia was started in the recovery room when visual analogue scale (VAS) scores were > 4. A bolus dose of morphine 3 mg was given to all the patients followed by i.v. PCA. Simultaneously, an infusion of ketamine 2.5 micrograms kg-1 min-1 or saline was started. Pain scores, morphine consumption and side effects were noted for up to 48 h after the start of PCA. VAS scores decreased significantly with time (P = 0.0001) and were similar (P = 0.3083) in both groups. Cumulative morphine consumption at 48 h was significantly lower in the ketamine group (28 mg) than in the control group (54 mg) (P = 0.0003). Nausea was less frequent in the ketamine group (P = 0.03). A randomized controlled trial was conducted to determine the effect of adding epidural ketamine to epidural morphine comparing between giving ketamine at preincisional time and postincisional time on postoperative analgesia in patients undergoing gynecological operations. Eighty patients scheduled for gynecological operation under combined epidural-general anesthesia were randomly divided into 4 groups. Group 1 received epidural morphine 3 mg before skin incision. Group 2 received epidural morphine 3 mg after skin incision. Group 3 received epidural morphine 3 mg and ketamine 30 mg before skin incision. Group 4 received epidural morphine 3 mg and ketamine 30 mg after skin incision. Lidocaine 2 per cent with epinephrine 1:200,000 was used as the main anesthetic agent during the operation in all groups. Postoperative analgesics were pethidine 1 mg/kg intramuscularly or paracetamol 1,000 mg oral. The time to the first analgesic requirement and pain during 48 h were recorded. The amount of pethidine and paracetamol required and the time to the first dose of analgesic requirement were not significantly different among the groups. There were no differences in the incidences of pruritus, nausea, vomiting and nightmare. We concluded that adding ketamine to epidural morphine either by preincisional or postincisional administration did not potentiate the analgesic effect of epidural morphine. Following a standardized general anaesthetic for total abdominal hysterectomy, patients received either patient controlled analgesia (PCA) with morphine 1 mg/ml (group M, n = 33) or morphine 1 mg/ml plus ketamine 2 mg/ml (group K, n = 37) for 48 hours in a randomized, double-blind fashion. In 43 women the area of allodynia around the scar was mapped as a measure of the degree of central sensitization. A significant reduction in the area of allodynia was found in those receiving ketamine with morphine (42 cm2 [interquartile range (IQR) 57] compared with 57 cm2 [IQR 82] z = -2.0, P = 0.04) in those receiving morphine alone. There were no significant differences between the two groups with respect to age, or weight, or between the subgroups within which the area of allodynia was measured with respect to length of incision. No significant differences were found between the groups with respect to pain scores, total or hourly drug consumption, patient satisfaction, nausea scores or antiemetic use. Patients in group K were more likely to require PCA for a shorter period than those in group M (median 40 hours, IQR 26 versus 48 hours IQR 7). Ten patients in group K were withdrawn because of side-effects (dysphoria n = 4, nausea n = 2, pruritus n = 4) compared with one in group M (nausea n = 1) (P = 0.006). The potential usefulness of ketamine after hysterectomy was offset by a high incidence of adverse effects and a lack of opioid-sparing effects, such that combined intravenous ketamine and morphine PCA as used in this study cannot be recommended for routine care. Ketamine may prevent postoperative hyperalgesia. In patients undergoing arthroscopic meniscectomy using general anesthesia, we tested whether a single intraoperative dose of ketamine enhanced postoperative analgesia and improved functional outcome compared with a typical multimodal analgesic regimen. After the induction of anesthesia, 50 patients were randomly assigned to ketamine (0.15 mg/kg IV just after the induction of anesthesia) or a vehicle placebo. Standardized general anesthesia included propofol, alfentanil, and nitrous oxide. Bupivacaine (0.5%) and morphine (5 mg) were given intraarticularly at the end of surgery. Postoperative analgesia was initially provided with morphine and subsequently with naproxen sodium (550 mg orally twice daily) and Di-Antalvic (400 mg acetaminophen and 30 mg dextropropoxyphene) as needed. Pain scores, analgesic requirements, side effects, and ability to walk were assessed in the ambulatory unit and at home for three postoperative days. Times to awakening and to discharge were similar in the two groups. However, the Ketamine group had significantly less postoperative pain at rest and during mobilization on Days 0, 1, and 2. Furthermore, they consumed significantly fewer Di-Antalvic tablets than the control group (13 [7-17] vs 27 [16-32], median [25%-75% interquartile range]). Patients given ketamine were also able to walk for longer periods of time on the first postoperative day. In conclusion, adding small-dose ketamine to a multimodal analgesic regimen improved postoperative analgesia and functional outcome after outpatient knee arthroscopy. This randomised, double-blind, prospective study compared morphine (1 mg x m(-1)) with the combination of morphine (1 mg x m(-1)) and ketamine (0.75 mg x m(-1)) via a patient-controlled analgesia system (PCAS) for postoperative pain control. A total of 42 female patients, ASA grade I and II, undergoing elective total abdominal hysterectomy was studied. During a standardised anaesthetic, a loading dose from the PCA syringe of 10 ml x m(-2) of body surface area was given. A PCAS with a background infusion was commenced postoperatively. Pain and side-effects were assessed using numerical scoring systems and cardiovascular and respiratory parameters were recorded. There was no statistically significant difference between the groups in total morphine consumption or pain scoring. Side-effect profiles and time to mobilisation were similar. This study concludes that the addition of ketamine to morphine, in this dosage regimen, administered via PCAS for postoperative pain control, does not confer benefit following total abdominal hysterectomy. Reduction of nociceptive input through blockade of N-methyl-D-aspartate (NMDA) receptors has been reported. We compared the effects of epidural S(+)-ketamine versus placebo on postoperative pain in a randomized, double-blinded study in 37 patients undergoing unilateral knee arthroplasty. After lumbar epidural anesthesia with ropivacaine (10 mg/mL, 10-20 mL), 19 patients received 0.9% epidural saline, and 18 patients received 0.25 mg/kg epidural S(+)-ketamine 10 min before surgical incision. After surgery, patient-controlled epidural analgesia with ropivacaine was provided. During the first 8 h after surgery, visual analog scale pain rating was similar between groups. Twenty-four and 48 h after surgery, patients anesthetized with ropivacaine had higher visual analog scale ratings at rest and during movement (P < 0.05) than patients anesthetized with S(+)-ketamine and ropivacaine. Forty-eight hours after surgery, patients anesthetized with ropivacaine also consumed more ropivacaine (558 +/- 210 mg) (P < 0.01) than those anesthetized with S(+)-ketamine and ropivacaine (319 +/- 204 mg). Adverse events were similar between groups. Patients who received S(+)-ketamine and ropivacaine rated the quality of their pain therapy better than those who received ropivacaine alone (P < 0.05). We conclude that the combination of S(+)-ketamine and ropivacaine in epidural anesthesia increases postoperative pain relief when compared with ropivacaine.
                Epidural S(+)-ketamine applied with ropivacaine before surgery is a rational approach to decrease injury-induced pain sensitization. Epidural blockade with an N-methyl-D-aspartate receptor antagonist and a local anesthetic may provide better analgesia in the postoperative period than a local anesthetic alone. Small-dose ketamine may enhance the analgesic effect of opiates. We studied the effect of IV coadministration of small-dose ketamine 50-100 microg/kg with morphine 50 microg/kg on postoperative morphine requirements and pain in 140 patients undergoing outpatient surgery. Midazolam 1-2 mg was administered in the holding area. Anesthesia was induced with propofol 2-2.5 mg/kg and was maintained with desflurane in a nitrous oxide/oxygen mixture. Patients received morphine 50 microg/kg with placebo (Group 1, n = 35) or ketamine 50 microg/kg IV (Group 2, n = 35), 75 microg/kg IV (Group 3, n = 35), or 100 microg/kg IV (Group 4, n = 35) 15 min before the end of the operation. Pain and drowsiness were assessed using visual analog scales on arrival in the recovery room, then every 15 min until the time of discharge to phase 2 recovery (phase 1 recovery). Morphine consumption in Groups 3 and 4 was approximately 40% less than that in the control group (91+/-9 and 89+/-8 microg/kg vs. 145+/-9 microg/kg; P<0.05 for both). Pain scores in Groups 3 and 4 were approximately 35% less than those in the control group at all time periods (P<0.0001 for all). There was no significant group difference in drowsiness scores. Small-dose ketamine 75-100 microg/kg IV, enhanced morphine-induced analgesia after outpatient surgery. Simultaneous use of small doses of ketamine with morphine enhances the pain relief produced by morphine.
                Simultaneous use of small doses of ketamine with morphine enhances the pain relief produced by morphine. To study the analgesic effect of epidural ketamine on postoperative pain and epidural PCA consumption after total abdominal hysterectomy.
                Sixty-one ASA I-II patients, 34-60 yr were randomly assigned into three groups. Epidural catheters were inserted before induction of anaesthesia. Patients in group I and II received 30 mg ketamine epidurally before induction of anaesthesia or 20 min after skin incision: group III received placebo. Postoperatively, on first analgesia request, sedation score, Visual Analogue Scale (VAS), Prince Henry Score (PHS) and Bromage motor weakness score were taken and followed by an epidural bolus of 9 ml bupivacaine 0.25% + 50 micrograms fentanyl. Analgesia was maintained by PCA with a mixture of bupivacaine 0.1% + fentanyl 0.001% epidurally. Measurements were repeated at 1, 2, 4, 8, 12 and 24 hr.
                First analgesia request was 17 +/- 6.8 min in the control group compared with 31.4 +/- 23.8 and 44 +/- 23.1 min for groups I and II respectively. The differences between group III and group I (P < 0.05) and between group III and group II (P < 0.01) were statistically significant. Twenty four hour PCA consumption was 101.2 +/- 47.2, 87 +/- 27 and 162 +/- 38 ml for groups I, II and III respectively. The differences between group III and group I and that between group III and group II were statistically significant (P < 0.001).
                Epidural ketamine 30 mg reduces post hysterectomy pain as evidenced by prolongation of time to first analgesia request and reduction in postoperative epidural PCA consumption. This effect is manifest whether ketamine is given before induction or 20 min after skin incision. This double-blind randomized study tested whether the addition of magnesium or ketamine to morphine for intravenous patient-controlled analgesia resulted in improved analgesic efficacy and lower pain scores compared with morphine patient-controlled analgesia alone after major abdominal surgery.
                Ninety patients (3 x 30) were randomly allocated to receive either morphine 0.4 mg mL(-1) (Group M) by patient-controlled analgesia, morphine 0.4mg mL(-1) + MgSO4 30mg mL(-1) (Group MM) or morphine 0.4 mg mL(-1) + ketamine 1 mg mL(-1) (Group MK). Postoperative analgesia was started when the verbal rating scale was > or = 2. Patients were first given a standardized loading dose (0.05 mg kg(-1)) of the study solution. They were then allowed to use bolus doses of this solution (0.0125 mg kg(-1) every 20 min without time limit). Discomfort, sedation, pain scores, cumulative morphine consumption and adverse effects were recorded up to 24 h after the start of the patient-controlled analgesia.
                The level of discomfort, level of sedation and verbal rating scores decreased significantly with time in all groups (P < 0.05). Both verbal rating and discomfort scores were significantly lower in Groups MM and MK at 15, 30 and 60 min compared with Group M (P < 0.001). Cumulative morphine consumption after 12 and 24 h was significantly higher in Group M alone (median 26 and 49 mg, respectively) compared with Group MM (24.2 and 45.7 mg) and Group MK (24.4 and 46.5 mg).
                In the immediate postoperative period, the addition of magnesium or ketamine to morphine for intravenous patient-controlled analgesia led to a significantly lower consumption of morphine. However, these differences are unlikely to be of any clinical relevance. NMDA receptors are assumed to play an important role for neuronal plasticity. In vitro and animal experiments confirmed that NMDA antagonistic drugs can prevent hyperexitability of dorsal root neurons after strong pain stimuli. Clinical data, however, are more or less controversial in this respect. It was the aim of the present prospective, randomised, double-blind study to verify if low-dose preoperative ketamine, an NMDA antagonist, provides relevant postoperative analgesia in surgical patients and to re-examine positive results published by other investigators. 80 ASA I-II patients undergoing elective laparoscopic or proctologic surgery received at induction of general anaesthesia a single i.v. bolus dose of either ketamine 0.15 mg/kg or placebo (0.9% NaCl). Postoperative analgesia was provided by i.v. patient-controlled analgesia (PCA) using the opioid piritramide. Cardiovascular parameters, respiration, sedation, cumulative piritramide consumption and pain scores (visual analogue scale 1-10, verbal rating scale 0-4) were monitored at 1, 2, 3, 4, 5, 6, 12 and 24 hours after surgery. Additionally, a retrospective pain score was documented after the 24 hours observation period. There was no statistically significant difference in any study parameter. Cumulative PCA piritramide consumption after 24 hours was 25.0+/-16.2 mg in the ketamine group and 29.5+/-20.4 mg in the placebo group. Ketamine-specific side effects such as hallucinations or bad dreams were not observed. It is concluded that under the study conditions used, low dose ketamine, contrary to previously reported results [30], does not provide a clinically relevant pre-emptive analgesic effect in postoperative patients. The preincisional use of ketamine combined with local tissue infiltration with Ropivacaine may reduce noxious input during surgery. The goal of this study was to examine whether this combination improves postoperative pain control after laparoscopic cholecystectomy.
                A total of 55 patients were randomly assigned to one of three groups. Group 1 received placebos preincisional. Group 2 received preincisional saline IV and local infiltration with 20 ml ropivacaine (10 mg/ml). Group 3 received preincisional ketamine 1 mg/kg IV and local infiltration with 20 ml ropivacaine (10 mg/ml). Postoperative pain was rated at 0, 3, 6, 12, 24, and 48 h postoperatively by visual analogue scale scores (VAS). Cumulative analgesic consumption and time until first analgesic medication request were recorded.
                Group 3 experienced significantly (p < 0.05) less pain than group 2 at 6 h and 12 h postoperatively. Groups 2 and 3 did not differ significantly by VAS at 0 h, 3 h, 24 h, and 48 h. Group 1 had significantly higher VAS scores than groups 2 and 3 at 0 h, 3 h, 6 h, 12 h, and 24 h postoperatively. The consumption of analgesics was significantly higher in group 1 than in groups 2 and 3. Although the consumption of analgesics was higher in group 3 than in group 2, this difference did not reach statistical significance. The time to first request for analgesics was significantly longer in groups 2 and 3 than in group 1, with no statistical difference between groups 2 and 3. Conclusion: Preincisional treatment with low-dose IV ketamine and local infiltration with ropivacaine 1% reduces postoperative pain after laparoscopic cholecystectomy. In a randomized, double-blinded study with three parallel groups, we assessed the analgesic effect of intraoperative ketamine administration in 45 ASA physical status I or II patients undergoing elective arthroscopic anterior ligament repair under general anesthesia. The patients received either IV ketamine 0.15 mg/kg after the induction of anesthesia and before surgical incision and normal saline at the end of surgery (PRE group); normal saline after the induction of anesthesia and before surgical incision and IV ketamine at the end of surgery (POST group); or normal saline at the beginning and the end of surgery (CONT group). Anesthesia was performed with propofol (2 mg/kg for induction, 60-200 microg x kg(-1) x min(-1) for maintenance), sufentanil (0.2 microg/kg 10 min after surgical incision, followed by an infusion of 0.25 microg x kg(-1) x h(-1) stopped 30 min before skinclosure), vecuronium (0.1 mg/kg), and 60% N2O in O2 via a laryngeal mask airway. Postoperative analgesia was initially provided with IV morphine in the postanesthesia care unit, then with IV patient-controlled analgesia started before discharge from the postanesthesia care unit. Pain scores, morphine consumption, side effects, and degree of knee flexion were recorded over 48 h and during the first and second physiotherapy periods, performed on Days 1 and 2. Patients in the ketamine groups required significantly less morphine than those in the CONT group over 48 h postoperatively (CONT group 67.7+/-38.3 mg versus PRE group 34.3+/-23.2 mg and POST group 29.5+/-21.5 mg; P < 0.01). Better first knee flexion (CONT group 35+/-10 degrees versus PRE group 46+/-12 degrees and POST group 47+/-13 degrees; P < 0.05) and lower morphine consumption (CONT group 3.8+/-1.7 mg versus PRE group 1.2+/-0.4 mg and POST group 1.4+/-0.4 mg; P < 0.05) were noted at first knee mobilization. No differences were seen between the PRE and POST groups, except for an increase in morphine demand in the PRE versus the POST group (P < 0.05) in the second hour postoperatively.
                We found that intraoperative small-dose ketamine reduced postoperative morphine requirements and improved mobilization 24 h after arthroscopic anterior ligament repair. No differences were observed in the timing of administration. Intraoperative small-dose ketamine may therefore be a useful adjuvant to perioperative analgesic management. Tissue injury induces central sensitization in the spinal cord dorsal horn neurons via mechanisms involving N-methyl-D-aspartate (NMDA) receptors, leading to secondary hyperalgesia. Using punctuate mechanical hyperalgesia as a measure of central sensitization, we examined whether induction and maintenance of central sensitization after surgery could be prevented by a low-dose infusion of the NMDA-receptor antagonist ketamine.
                Twenty living kidney donors were included in a randomized, double-blind, parallel, two-group study. Before start of surgery 10 patients received an i.v. bolus of racemic ketamine 0.5 mg.kg-1, followed by a continuous i.v. infusion of ketamine 2 micrograms.kg-1.min-1 for 24 h, thereafter 1 microgram.kg-1.min-1 for another 48 h. The control group received placebo bolus and infusion. A standard general anaesthesia including fentanyl was used. Patient-controlled (PCA) i.v. morphine was used for postoperative analgesia. Punctuate mechanical hyperalgesia and temporal summation of mechanical stimuli causing "wind-up pain" were measured using von Frey filaments.
                The area of punctuate mechanical hyperalgesia was significantly reduced in the ketamine group 1, 3 and 7 d after the operation (P < 0.01-0.001). "Wind-up pain" was also reduced by ketamine (P < 0.05). PCA morphine consumption and pain intensity (visual analogue scale) differed between groups only during the first hours after surgery, in favour of ketamine. The ketamine patients scored significantly higher on a global satisfaction score. Side-effects were most frequent in the placebo group.
                Low-dose i.v. infusion of ketamine during and after surgery reduces mechanical punctuate hyperalgesia surrounding the surgical incision. These results indicate that blockade of NMDA receptors prevents the central sensitization caused by nociceptive input during and after surgery. In this study, we evaluated the preemptive effect of a small dose of ketamine on postoperative wound pain. In a randomized, double-blinded, controlled trial, we compared the analgesic requirement in patients receiving preincision ketamine with ketamine after skin closure or placebo after gynecologic laparoscopic surgery. One-hundred-thirty-five patients were randomly assigned to receive preincision or postoperative ketamine 0.15 mg/kg or saline IV. Anesthetic technique was standardized. Patients were interviewed regularly up to 4 wk after surgery. Pain score, morphine consumption, side effects, and quality of recovery score were recorded. Patients receiving preincision ketamine had a lower pain score in the first 6 h after operation compared with the postoperative (P = 0.001) or placebo groups (P < 0.001). The mean (95% confidence intervals) time to first request for analgesia in the preincision group, 1.8 h (1.4-2.1), was longer than the postoperative group, 1.2 h (0.9-1.5; P < 0.001), or the placebo group, 0.7 h (0.4-0.9; P < 0.001). The mean +/- SD morphine consumption in the preincision group, 1.5 +/- 2.0 mg, was less than that in the postoperative group, 2.9 +/- 3.1 mg (P = 0.04) and the placebo group, 3.4 +/- 2.7 mg (P = 0.003). There was no significant difference among groups with respect to hemodynamic variables or side effects. No patient complained of hallucinations or nightmares. We conclude that a small dose of ketamine is not only safe, but it also provides preemptive analgesia in patients undergoing gynecologic laparoscopic surgery.
                In women undergoing laparoscopic gynecologic surgery, a small preoperative dose of ketamine (0.15 mg/kg) produced preemptive analgesia. There were no significant hemodynamic and psychological side effects with this dose. In a randomized, double-blinded study, we evaluated the analgesic effect of ketamine in the management of pain in a surgical intensive care unit after major abdominal surgery. Patients received morphine patient-controlled analgesia with either placebo (Group M) or ketamine (Group K). Morphine was administered with initial loading doses of 2 mg until the visual analog scale (VAS) score was <30 and thereafter with bolus doses of 1 mg and a lockout time of 7 min. Ketamine was administered with an initial bolus of 0.5 mg/kg followed by a perfusion of 2 micro g x kg(-1) x min(-1) during the first 24 h and 1 micro g x kg(-1) x min(-1) during the following 24 h. The 4-h cumulative morphine doses were measured over 48 h. The VAS scores at rest and at mobilization were measured every 4 h during 48 h. A total of 101 patients were enrolled, and 93 were analyzed (41 in Group K and 52 in Group M). VAS scores at rest and at mobilization were similar. The cumulative consumption of morphine was significantly smaller in Group K (P < 0.05). We concluded that small doses of ketamine were a valuable adjunct to opioids in surgical intensive care unit patients after major abdominal surgery. We investigated whether intraoperative 'subanesthetic doses' of ketamine have a postoperative anti-hyperalgesic and an analgesic effect and which is the preferential route of administration, either systemic (intravenous, i.v.) or epidural. One hundred patients scheduled for rectal adenocarcinoma surgery under combined epidural/general anesthesia were included. Before skin incision all the patients received an epidural bolus followed by an infusion of continuous bupivacaine/sufentanil/clonidine mixture. They were randomly assigned to receive no ketamine (group 1), i.v. ketamine at the bolus dose of 0.25 mg/kg followed by an infusion of 0.125 mg/kg per h (group 2), 0.5 mg/kg and 0.25 mg/kg per h (group 3), epidural ketamine 0.25 mg/kg and 0.125 mg/kg per h (group 4), or 0.5 mg/kg and 0.25 mg/kg per h (group 5). All i.v. and epidural analgesics were stopped at the end of surgery and patients were connected to an i.v. morphine patient-controlled analgesia (PCA) device. Short-term postoperative analgesia (72 h) was assessed by pain visual analog scale scores at rest, cough, and movements as well as by PCA requirements. Wound mechanical hyperalgesia was evaluated and residual pain was assessed by asking the patients at 2 weeks, and 1, 6, and 12 months. The area of hyperalgesia and morphine PCA requirements were significantly reduced in group 3. These patients reported significantly less residual pain until the sixth postoperative month. These observations support the theory that subanesthetic doses of i.v. ketamine (0.5 mg/kg bolus followed by 0.25 mg/kg per h) given during anesthesia reduce wound hyperalgesia and are a useful adjuvant in perioperative balanced analgesia. Moreover, they show that the systemic route clearly is the preferential route. We designed this double-blinded, randomized, controlled study to evaluate the effect of small-dose ketamine IV in combination with epidural morphine and bupivacaine on postoperative pain after renal surgery. An epidural catheter was inserted, and the administration of morphine and bupivacaine was started before surgery. Forty patients were assigned to one of two groups (ketamine or control). The ketamine group was administered a ketamine bolus and infusion during surgery. The median visual analog pain scale (VAS) scores at rest were significantly lower in the ketamine group during the first 6 h (P < 0.01). VAS pain scores on coughing were also significantly lower in the ketamine group (P < 0.01). Cumulative postoperative total analgesic consumption was less in the ketamine group on Days 1 and 2 (P < 0.001). The first analgesic demand time was shorter in the control group (9.2 +/- 11.5 min) than in the ketamine group (22.3 +/- 17.1 min) (P < 0.0001). The incidence of nausea and pruritus was more frequent in the control group (P < 0.05). In conclusion, postoperative analgesia was more effective when spinal cord and brain sensitization were blocked by a combination of epidural morphine/bupivacaine and IV ketamine.
                Renal nociception conducted multisegmentally by both the spinal nerves (T10 to L1) and the vagus nerve cannot be blocked by epidural analgesia alone. We demonstrated that IV ketamine had an improved analgesic or opioid-sparing effect when it was combined with epidural bupivacaine and morphine after renal surgery. This study evaluated the pre-emptive analgesic effect of intravenous (i.v.) (R)-ketamine in laparoscopic cholecystectomy. (R)-ketamine was used due to the lower incidence of side-effects.
                Sixty patients who underwent surgery under general anesthesia were randomly allocated to 3 groups and studied in a double-blind manner. Two i.v. injections were administered: one after induction of anesthesia, approximately 3 min before surgery, and one after surgery. The placebo group (PLA, n = 20) received saline in both injections. The preoperative group (PRE, n = 20) received (R)-ketamine 1 mg/kg and then saline. The postoperative group (POST, n = 20) received saline and then (R)-ketamine 1 mg/kg. Postoperatively, the patients used a patient-controlled analgesia (PCA) pump. Pain was evaluated with a visual analog scale (VAS) at 30 min and every hour for 4 h and with a verbal rating scale (VRS) at 24 h and after 7 days.
                There were no occurrence of side-effects from (R)-ketamine. VAS and VRS at 1, 2, 3, and 4 h postoperatively showed no statistical differences. In the POST group, extubation was delayed and pain score (VAS) at 30 min postoperatively was significantly lower (P < 0.05) than the two other groups. There were no statistical differences in meperidine consumption during the first 4 h postoperatively and no differences in consumption of analgesics at 24 h and 7 days.
                In this study a 1 mg/kg dose of (R)-ketamine given at the end of surgery exerted a short-lasting hypnotic and analgesic effect. The same dose given preoperatively did not show postoperative analgesic effect or pre-emptive effect. The use of intraoperative racemic ketamine for pain prevention after abdominal surgery is controversial. We compared one preincisional i.v. injection of S(+)-ketamine with its preincisional and repeated intraoperative use in 45 patients undergoing surgery with epidural and general anesthesia. S(+)-ketamine is a new drug formulation that contains the more potent S(+)-stereoisomer of ketamine. Patients were randomized to receive placebo, 0.5 mg/kg preincisional S(+)ketamine, or 0.5 mg/kg preincisional and 0.2 mg/kg intraoperative S(+)-ketamine repeated at 20-min intervals. In the postoperative period, epidural ropivacaine (2 mg/mL; 0.12 mL.kg(-1).h(-1)) was infused for pain therapy. Patients who received repeated S(+)-ketamine reported smaller pain scores than those who received placebo after awakening and 3 and 6 h later (P < or = 0.05). Fewer patients with repeated S(+)-ketamine required additional analgesics than those with placebo (P < or = 0.05). Cumulative consumption of additional diclofenac and dextropropoxyphene at 24 h was less after single (P < 0.05) and repeated (P < 0.05) S(+)-ketamine versus placebo. After awakening, patients who received repeated S(+)-ketamine reported being in a better mood than those in the other groups (P < 0.05). No psychotomimetic side effects were noted. In conclusion, preincisional and repeated intraoperative small-dose S(+)-ketamine added to general and epidural anesthesia causes better postoperative pain relief than general and epidural anesthesia alone.
                After major visceral surgery, preincisional and repeated intraoperative small-dose S(+)-ketamine added to general and epidural anesthesia causes better postoperative pain relief than general and epidural anesthesia alone. To compare the analgesic and side effects of preemptively used epidural ketamine +bupivacaine, neostigmine +bupivacaine, and bupivacaine alone on postoperative analgesia after major abdominal surgery.
                Randomized, controlled study.
                Inpatient anesthesia at the department of surgery of a metropolitan hospital.
                30 ASA physical status I, II, and III patients scheduled for abdominal surgery.
                Group K received 1 mL (50 mg) ketamine and 5 mL (25 mg) bupivacaine epidurally, Group N received 1 mL (0.5 mg) neostigmine and 5 mL (25 mg) bupivacaine epidurally, and Group B received 1 mL saline and 5 mL (25 mg) bupivacaine epidurally 30 minutes before operation. All patients underwent anesthesia induction with thiopental and vecuronium; anesthesia was maintained with isoflorane and vecuronium. For postoperative analgesia, all patients received epidural morphine for 48 hours postoperatively.
                Standard monitoring included: 48 hours of analgesic requirement, visual analog scale (VAS), mean arterial pressure (MAP), and heart rate (HR) in the 1st, 2nd, 6th, 12th, 24th, and 48th hours. Data were analyzed using Kruskall-Wallis and Mann Whitney U tests, with a p < 0.05 considered statistically significant. No significant differences were observed regarding MAP and HR among the groups during the study period. In Group N, VAS was significantly lower than Group K and Group B. The total opioid consumption in Group N was significantly lower than in Groups K and B in the first 48 hours after the operation.
                Preemptive neostigmine can be a good choice for postoperative analgesia. In a randomised, double-blind prospective study we compared the effects on postoperative pain and analgesic consumption of intra-operative s(+)-ketamine (100 microg.kg-1 bolus and a continuous infusion of 2 microg.kg-1.min-1) followed by postoperative patient-controlled analgesia with morphine (1 mg per bolus) plus s(+)-ketamine (0.5 mg per bolus), or intra-operative saline followed by postoperative patient-controlled analgesia morphine (1 mg per bolus) alone. A total of 28 male patients undergoing radical prostatectomy were studied. Morphine consumption, pain scores, pressure algometry and adverse effects were recorded for 48 h after surgery. Cumulative morphine consumption was significantly lower in the ketamine/morphine group (47.9 +/- 26.2 mg) than in the saline/morphine group (73.4 +/- 34.8 mg; p = 0.049). Pain scores at rest were significantly lower in the ketamine/morphine group across the 48-h study period (p = 0.01). No significant differences were found in pressure algometry measurements or the occurrence of adverse effects. The aim of this study was to compare the analgesic effects and pharmacokinetics of epidural versus intravenous administration of low doses of ketamine.
                45 patients scheduled for selective gastrectomy were randomly assigned into 3 groups: 0.5mg/kg ketamine administered epidurally (Kepi group), 0.5 mg/kg ketamine administered intravenously (Kiv group), or 10ml normal saline administered epidurally (Ctr group). Analgesic effects were evaluated using Visual Analog Scale (VAS) pain scores at rest, time to first request for analgesic (TFA), and subsequent morphine consumption. The plasma concentration of ketamine was measured with high performance liquid chromatography (HPLC) in the Kepi and Kiv groups. The elimination half-life of ketamine was calculated.
                Patients in the Kepi group had significantly lower VAS pain scores, longer TFA, and lower morphine consumption than patients in the Kiv or Ctr groups. Compared with intravenous administration, epidural administration of ketamine resulted in higher plasma concentrations from 90 minutes to 48 hours after injection, and much longer elimination half-life of ketamine, but a lower maximum plasma concentration of ketamine.
                The results suggest that epidural administration of a low dose of ketamine provides more effective analgesic effects as seen post-operatively than intravenous administration. The prolonged half-life and high plasma sustained concentration of epidural ketamine might account for the difference in analgesic effects. We designed this double-blind study to evaluate the effect of adding small-dose ketamine in a multimodal regimen of postoperative patient-controlled epidural analgesia (PCEA). Ninety-one patients, ASA physical status I-III, undergoing major surgery, received a standardized general anesthesia and epidural catheterization in an appropriate intervertebral space after surgery. A PCEA device was programmed to deliver a regimen of morphine 0.02 mg/mL, bupivacaine 0.8 mg/mL, and epinephrine 4 microg/mL, with the addition of ketamine 0.4 mg/mL (ketamine, n = 45) or without (control, n = 46). The mean visual analog pain scale (VAS) scores during cough or movement for the first 3 days after surgery were higher in the control group than in the ketamine group (P < 0.05), whereas the mean VAS score at rest for the first 2 days were higher in the control group than in the ketamine group (P < 0.05). Furthermore, patients in the control group consumed more multimodal analgesics than patients in the ketamine group for the first 2 days (P < 0.05). The sedation scores and the incidence of side effects (pruritus, nausea, emesis, sleep deprivation, motor block, and respiration depression) were similar between the two groups. We conclude that adding ketamine 0.4 mg/mL in a multimodal PCEA regimen provides better postoperative pain relief and decreases consumption of analgesics. Implications: Many studies have evaluated one or a combination of two analgesics for postoperative pain control, but few have examined a multimodal approach using three or four different epidural analgesics. This study demonstrates an additive analgesic effect when ketamine is added to a multimodal analgesic treatment. Several studies report that when small-dose racemic ketamine, an N-methyl-D-aspartate receptor antagonist, is administered perioperatively, opioid consumption is reduced postoperatively. S(+)-ketamine has a higher affinity for the N-methyl-D-aspartate receptor and less-serious side effects than racemic ketamine. Thirty patients scheduled for elective arthroscopic anterior cruciate ligament repair were enrolled in this randomized, double-blinded clinical trial designed to determine the preemptive effect of S(+)-ketamine on postoperative analgesia requirements in a setting of clinically relevant perioperative analgesia. Total IV anesthesia was induced and maintained with remifentanil (0.125-1.0 microg x kg(-1) x min(-1)) and a propofol target-controlled infusion (target 2-4 microg/mL). The Ketamine group received a bolus of 0.5 mg/kg S(+)-ketamine before incision, followed by a continuing infusion of 2 microg x kg(-1) x min(-1) until 2 h after emergence from anesthesia. The Control group received NaCl in the same sequence. After IV morphine provided pain relief down to < or =3 on a visual analog scale scored from 0 to 10, patients were connected to a patient-controlled analgesia device. There were no significant differences between the two groups in terms of total morphine consumption or VAS scores, either at rest or with movement. In our study, S(+)-ketamine did not contribute to postoperative pain reduction, possibly because of the clinically routine perioperative opioid analgesia.
                Small-dose S(+)-ketamine had no positive effect on postoperative analgesia when administered perioperatively for elective arthroscopic anterior cruciate ligament repair. Unlike investigations of the racemic mixture of ketamine, our study methods included timely standard-practice perioperative opioid analgesia, which seems to make supplemental analgesia unnecessary. Morphine and ketamine may prevent central sensitization during surgery and result in preemptive analgesia. The reliability of preemptive analgesia, however, is controversial.
                Gastrectomy patients were given preemptive analgesia consisting of epidural morphine, intravenous low-dose ketamine, and combinations of these in a randomized, double-blind manner. Postsurgical pain intensity was rated by a visual analog scale, a categoric pain evaluation, and cumulative morphine consumption.
                Preemptive analgesia by epidural morphine and by intravenous low-dose ketamine were significantly effective but not definitive. With epidural morphine, a significant reduction in visual analog scale scores at rest was observed at 24 and 48 h, and morphine consumption was significantly lower at 6 and 12 h, compared with control values. With intravenous ketamine, visual analog scale scores at rest and morphine consumption were significantly lower at 6, 12, 24, and 48 h than those in control subjects. The combination of epidural morphine and intravenous ketamine provided definitive preemptive analgesia: Visual analog scale scores at rest and morphine consumption were significantly the lowest at 6, 12, 24, and 48 h, and the visual analog scale score during movement and the categoric pain score also were significantly the lowest among the groups.
                The results suggest that for definitive preemptive analgesia, blockade of opioid and N-methyl-d-aspartate receptors is necessary for upper abdominal surgery such as gastrectomy; singly, either treatment provided significant, but not definitive, postsurgical pain relief. Epidural morphine may affect the spinal cord segmentally, whereas intravenous ketamine may block brain stem sensitization via the vagus nerve during upper abdominal surgery. The purpose of this study was to compare morphine with ketamine to morphine alone in a double-blind investigation of postsurgical pain control.
                Forty-two ASA 1 and 2 patients undergoing elective microdiscectomy were administered either 1 mg.ml-1 of morphine (n = 20) or 1 mg.ml-1 of both morphine and ketamine (n = 22) via iv patient controlled analgesia (IVPCA). Pain relief and side effects were assessed at 24 hr after surgery.
                The mean (SD) visual analogue scale (VAS) pain rating of 2.3 (1.67) for patients receiving morphine with ketamine was lower (P < 0.001) than the VAS scores of patients receiving only morphine 4.5 (1.54). Patients receiving morphine and ketamine also had less difficulty with side effects, reporting less nausea (P < 0.05), pruritus (P < 0.001), and urinary retention (P < 0.05). Although dysphoria is reported to be a common side effect of ketamine, complaints of dysphoria were rare in both groups, with only one subject (5%) in the morphine with ketamine group and three (15%) subjects receiving morphine alone reporting this side effect.
                IVPCA ketamine in combination with morphine provides superior postsurgical pain relief at lower dosage and with fewer side effects than morphine alone. In this prospective, randomized, and double-blinded clinical trial, we evaluated the efficacy of preincisional administration of epidural ketamine with morphine compared with epidural morphine alone for postoperative pain relief after major upper-abdominal surgery. We studied 50 ASA I and II patients undergoing major upper-abdominal procedures. These patients were randomly allocated to one of the two treatment groups: patients in Group 1 received epidural morphine 50 microg/kg, whereas those in Group 2 received epidural ketamine 1 mg/kg combined with 50 microg/kg of morphine 30 min before incision. Intraoperative analgesia was provided in addition, with IV morphine, and the requirement was noted. A blinded observer using a visual analog scale for pain assessment observed patients for 48 h after surgery. Additional doses of epidural morphine were provided when the visual analog scale score was more than 4. Analgesic requirements and side effects were compared between the two groups. There were no differences between the two groups with respect to age, sex, weight, or duration or type of the surgical procedures. The intraoperative morphine requirement was significantly (P = 0.018) less in Group 2 patients (median, 6.8 mg; range, 3-15 mg) compared with patients in Group 1 (median, 8.3 mg; range, 4.5-15 mg). The time for the first requirement of analgesia was significantly (P = 0.021) longer (median, 17 h; range, 10-48 h) in Group 2 patients than in Group 1 (median, 12 h; range, 4-36 h). The total number of supplemental doses of epidural morphine required in the first 48 h after surgery was comparable (P = 0.1977) in both groups. Sedation scores were similar in both groups. One patient in Group 2 developed hallucinations after study drug administration. None of the patients in either group developed respiratory depression. Other side effects, such as pruritus, nausea, and vomiting, were also similar in both groups. Although the addition of ketamine had synergistic analgesic effects with morphine (reduced intraoperative morphine consumption and prolonged time for first requirement of analgesia), there was no long- lasting preemptive benefit seen with this combination (in terms of reduction in supplemental analgesia) for patients undergoing major upper-abdominal procedures.
                Ketamine added to epidural morphine given before surgery can decrease postoperative pain by its preemptive effect, opioid potentiation, and prevention of acute opioid tolerance. A single epidural bolus of 1 mg/kg of ketamine with morphine given before major upper-abdominal surgery did not result in a clinically relevant reduction in postoperative pain relief. To evaluate the efficacy of the combination of epidural ketamine and morphine compared with epidural morphine alone for postoperative pain relief following major upper abdominal surgery.
                Prospective, randomized, double-blinded study.
                Tertiary care referral and teaching hospital.
                46 ASA physical status I and II patients who underwent major upper abdominal procedures.
                Patients were randomly allocated to one of the two treatment groups: patients in Group 1 received epidural morphine 50 microg/kg whereas patients in Group 2 received epidural ketamine 1 mg/kg combined with 50 microg/kg of morphine postoperatively.
                A blinded observer using a visual analog scale (VAS) for pain assessment followed up patients for 48 hours postoperatively. Top-up dose of epidural morphine was provided when VAS was higher than 4. Analgesic requirements and side effects were compared between the two groups.
                Only 40 patients completed the study. There were no differences between the two groups with respect to age, gender, weight, duration, or type of surgical procedure or intraoperative opioid requirements. Onset of analgesia was faster (p < 0.001) in Group 2 (11 min) than in Group 1 patients (25 min). The time for first requirement of analgesia was significantly (p < 0.01) longer (19.8 +/- 9.8 hours) in Group 2 patients than Group 1 (12.8 +/- 6.2 hours). Total number of supplemental doses of epidural morphine required in the first 48 hours postoperatively was also significantly less (p < 0.005) in Group 2 compared to Group 1. Patients in Group 2 had higher sedation scores than Group I patients for the first 2 hours postoperatively. None of the patients in either group developed hallucinations or respiratory depression. Other side effects such as pruritus, nausea, and vomiting were also similar in both groups.
                The addition of epidural ketamine 1 mg/kg to morphine 50 microg/kg improved analgesia after major upper abdominal surgery without increasing side effects. We studied 60 patients undergoing operation on the kidney with combined general and epidural anaesthesia, in a double-blind, randomized, controlled study. Patients were allocated to receive a preoperative bolus dose of ketamine 10 mg i.v., followed by an i.v. infusion of ketamine 10 mg h-1 for 48 h after operation, or placebo. During the first 24 h after surgery, all patients received 4 ml h-1 of epidural bupivacaine 2.5 mg ml-1. From 24 to 48 h after operation, patients received epidural morphine 0.2 mg h-1 preceded by a bolus dose of 2 mg. In addition, patient-controlled analgesia (PCA) with i.v. morphine (2.5 mg, lockout time 15 min) was offered from 0 to 48 h after operation. Patients who received ketamine felt significantly more sedated at 0-24 h, but not at 24-48 h after operation, compared with patients who received placebo (P = 0.002 and P = 0.127, respectively). There were no significant differences in pain (VAS) at rest, during mobilization or cough, PCA morphine consumption, sensory block to pinprick, pressure pain detection threshold assessed with an algometer, touch and pain detection thresholds assessed with von Frey hairs, peak flow or side effects other than sedation. The power of detecting a reduction in VAS scores of 20 mm in our study was 80% at the 5% significance level. We conclude that we were unable to demonstrate an (additive) analgesic or opioid sparing effect of ketamine 10 mg h-1 i.v. combined with epidural bupivacaine at 0-24 h, or epidural morphine at 24-48 h after renal surgery. Relative large-dose intraoperative remifentanil could lead to the need for more postoperative analgesics. Intraoperative N-methyl-D-aspartate receptor antagonists, such as ketamine, decrease postoperative opioid use. We therefore tested the hypothesis that intraoperative small-dose ketamine improves postoperative analgesia after major abdominal surgery with remifentanil-based anesthesia. Fifty patients undergoing abdominal surgery under remifentanil-based anesthesia were randomly assigned to intraoperative ketamine or saline (control) supplementation. The initial ketamine dose of 0.15 mg/kg was followed by 2 microg. kg(-1). min(-1). In both groups, desflurane was kept constant at 0.5 minimum alveolar anesthetic concentration without N(2)O, and a remifentanil infusion was titrated to autonomic responses. All patients were given 0.15 mg/kg of morphine 30 min before the end of surgery. Pain scores and morphine consumption were recorded for 24 postoperative h. Less of the remifentanil was required in the Ketamine than in the Control group (P < 0.01). Pain scores were significantly larger in the Control group during the first 15 postoperative min but were subsequently similar in the two groups. The Ketamine patients required postoperative morphine later (P < 0.01) and received less morphine during the first 24 postoperative h: 46 mg (interquartile range, 34-58 mg) versus 69 mg (interquartile range, 41-87 mg, P < 0.01). No psychotomimetic symptoms were noted in either group. In conclusion, supplementing remifentanil-based anesthesia with small-dose ketamine decreases intraoperative remifentanil use and postoperative morphine consumption without increasing the incidence of side effects. Thus, intraoperative small-dose ketamine may be a useful adjuvant to intraoperative remifentanil.
                Supplementing remifentanil-based anesthesia with small-dose ketamine decreased intraoperative remifentanil use and postoperative morphine consumption. These data demonstrate that N-methyl-D-aspartate antagonists, such as ketamine, can be a useful adjuvant to intraoperative remifentanil.
Ketamine in subanaesthetic dose (that is a dose which is below that required to produce anaesthesia) is effective in reducing morphine requirements in the first 24 hours after surgery. Ketamine also reduces postoperative nausea and vomiting. Adverse effects are mild or absent.