Ketamine does not decrease postoperative pain after remifentanil-based anaesthesia for tonsillectomy in adults

The interest of ketamine as an adjuvant to fentanyl in post-tonsillectomy analgesia in children: a randomized controlled trial

Introduction

tonsillectomy is the most commonly performed surgery in children. It is a painful surgery, which is often an ordeal for both children and their parents. The study aimed to evaluate the effects of ketamine used instead of or as an adjuvant to fentanyl on early postoperative pain scores in children undergoing tonsillectomy.

Methods

we conducted a double-blind prospective randomized study including 60 children, aged between 2 and 7 years, scheduled to undergo adenotonsillectomy. Patients were randomly assigned to one of three groups: group G1 received 2 μg/kg of fentanyl, group G2 received 0.5 mg/kg of ketamine and group G3 received an association of fentanyl 1μg/kg and 0.25 mg/kg of ketamine. We recorded postoperative analgesic requirements and side effects. The pain was assessed in the post-anesthesia care unit (PACU) by the face, legs, activity, cry, and controllability (FLACC) pain scale. We evaluated the requirement for additional analgesics, postoperative nausea, and vomiting.

Results

sixty children were included. Twenty patients were randomly assigned to one of three groups. Better control of pain was noted in group G3 ( Median FLACC scale G3=0 Inter quartile range (IQR)=-1 - 1), with a significant difference at 30 min compared to both groups G1 (median FLACC scale G1=3 [IQR=-1 - 7]; p=0,008) and G2 (median FLACC scale G2=1 [IQR=-2 - 4]; p=0.036). The need for additional analgesia and side effects in the PACU were comparable for the three groups.

Conclusion

ketamine associated with fentanyl provides satisfactory early analgesia and can even replace fentanyl during tonsillectomy.

Posttonsillectomy Pain Relief and Wound Healing by Applying Bismuth Iodoform Paraffin Paste (BIPP) to Dissected Tonsillar Beds

Introduction  Tonsillectomy is one of the most common operations performed by otorhinolaryngology surgeons worldwide; however, the insufficient quality of the postoperative pain management and effective posttonsillectomy pain relief remain a clinical dilemma. Objective  To evaluate the efficacy of applying bismuth iodine paraffin paste (BIPP) to the dissected fossa as an adjuvant therapy for a better outcome in terms of posttonsillectomy pain management and due to its wound healing properties. Methods  The present is a prospective randomized control pilot study with 44 patients aged > 7 years who underwent tonsillectomy. The patients were divided into two groups: the control group and the group that had BIPP applied to the dissected tonsillar fossa. The visual analogue scale score and the post-onsillectomy percentage of tonsillar fossa epithelization were recorded and evaluated. Results  Both subjectively and objectively, there a was statistically significant pain-relieving effect in the BIPP group within the first 5 postoperative days ( p  < 0.05). From postoperative day 3 onward, the dissected area of the tonsillar fossa healed significantly faster in the BIPP group compared with the control group, and it became stable on day 14. Conclusion  The topical application of BIPP showed a better pain-relieving effect, it was safe, and hastened wound healing after tonsillectomy.

Systematic review of analgesics and dexamethasone for post-tonsillectomy pain in adults

BACKGROUND

Intense pain can last several days after tonsillectomy. It is often undertreated and improved analgesic strategies that can be safely used at home are needed.

METHODS

We conducted a systematic review and meta-analysis on the effectiveness of systemic medications used for post-tonsillectomy pain in adult and adolescent (13 yr old) patients. Studies were identified from PubMed, the Cochrane Library, and by hand searching reference lists from studies and review articles. Randomised, double-blind, placebo-controlled studies reporting on pain intensity or use of rescue analgesia were included.

RESULTS

Twenty-nine randomised controlled trials representing 1816 subjects met the inclusion criteria. Follow-up time was ≤24 h in 15 studies, in which the majority were taking nonsteroidal anti-inflammatory drugs. Thirteen studies were suitable for meta-analysis. In pooled analysis, paracetamol, dexamethasone, and gabapentinoids reduced pain intensity on the day of operation. In individual studies, ketoprofen, ibuprofen, lornoxicam, parecoxib, rofecoxib, indomethacin and dextromethorphan reduced pain intensity, need for rescue analgesics, or both on the day of operation. Oral celecoxib for 2 postoperative weeks or i.v. ketamine on the day of operation were not effective at the studied doses. Dexamethasone in multiple doses provided analgesia beyond 1 postoperative day. Pain was moderate to strong in both study and control groups during the first postoperative week.

CONCLUSIONS

Single analgesics and dexamethasone provide only a weak to moderate effect for post-tonsillectomy pain on the day of operation and thus a multimodal analgesic strategy is recommended. Short follow-up times and clinical heterogeneity of studies limit the usefulness of results.

Perioperative intravenous ketamine for acute postoperative pain in adults

BACKGROUND

Inadequate pain management after surgery increases the risk of postoperative complications and may predispose for chronic postsurgical pain. Perioperative ketamine may enhance conventional analgesics in the acute postoperative setting.

OBJECTIVES

To evaluate the efficacy and safety of perioperative intravenous ketamine in adult patients when used for the treatment or prevention of acute pain following general anaesthesia.

SEARCH METHODS

We searched CENTRAL, MEDLINE and Embase to July 2018 and three trials registers (metaRegister of controlled trials, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP)) together with reference checking, citation searching and contact with study authors to identify additional studies.

SELECTION CRITERIA

We sought randomised, double-blind, controlled trials of adults undergoing surgery under general anaesthesia and being treated with perioperative intravenous ketamine. Studies compared ketamine with placebo, or compared ketamine plus a basic analgesic, such as morphine or non-steroidal anti-inflammatory drug (NSAID), with a basic analgesic alone.

DATA COLLECTION AND ANALYSIS

Two review authors searched for studies, extracted efficacy and adverse event data, examined issues of study quality and potential bias, and performed analyses. Primary outcomes were opioid consumption and pain intensity at rest and during movement at 24 and 48 hours postoperatively. Secondary outcomes were time to first analgesic request, assessment of postoperative hyperalgesia, central nervous system (CNS) adverse effects, and postoperative nausea and vomiting. We assessed the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We included 130 studies with 8341 participants. Ketamine was given to 4588 participants and 3753 participants served as controls. Types of surgery included ear, nose or throat surgery, wisdom tooth extraction, thoracotomy, lumbar fusion surgery, microdiscectomy, hip joint replacement surgery, knee joint replacement surgery, anterior cruciate ligament repair, knee arthroscopy, mastectomy, haemorrhoidectomy, abdominal surgery, radical prostatectomy, thyroid surgery, elective caesarean section, and laparoscopic surgery. Racemic ketamine bolus doses were predominantly 0.25 mg to 1 mg, and infusions 2 to 5 µg/kg/minute; 10 studies used only S-ketamine and one only R-ketamine. Risk of bias was generally low or uncertain, except for study size; most had fewer than 50 participants per treatment arm, resulting in high heterogeneity, as expected, for most analyses. We did not stratify the main analysis by type of surgery or any other factor, such as dose or timing of ketamine administration, and used a non-stratified analysis.Perioperative intravenous ketamine reduced postoperative opioid consumption over 24 hours by 8 mg morphine equivalents (95% CI 6 to 9; 19% from 42 mg consumed by participants given placebo, moderate-quality evidence; 65 studies, 4004 participants). Over 48 hours, opioid consumption was 13 mg lower (95% CI 10 to 15; 19% from 67 mg with placebo, moderate-quality evidence; 37 studies, 2449 participants).Perioperative intravenous ketamine reduced pain at rest at 24 hours by 5/100 mm on a visual analogue scale (95% CI 4 to 7; 19% lower from 26/100 mm with placebo, high-quality evidence; 82 studies, 5004 participants), and at 48 hours by 5/100 mm (95% CI 3 to 7; 22% lower from 23/100 mm, high-quality evidence; 49 studies, 2962 participants). Pain during movement was reduced at 24 hours (6/100 mm, 14% lower from 42/100 mm, moderate-quality evidence; 29 studies, 1806 participants), and 48 hours (6/100 mm, 16% lower from 37 mm, low-quality evidence; 23 studies, 1353 participants).Results for primary outcomes were consistent when analysed by pain at rest or on movement, operation type, and timing of administration, or sensitivity to study size and pain intensity. No analysis by dose was possible. There was no difference when nitrous oxide was used. We downgraded the quality of the evidence once if numbers of participants were large but small-study effects were present, or twice if numbers were small and small-study effects likely but testing not possible.Ketamine increased the time for the first postoperative analgesic request by 54 minutes (95% CI 37 to 71 minutes), from a mean of 39 minutes with placebo (moderate-quality evidence; 31 studies, 1678 participants). Ketamine reduced the area of postoperative hyperalgesia by 7 cm² (95% CI -11.9 to -2.2), compared with placebo (very low-quality evidence; 7 studies 333 participants). We downgraded the quality of evidence because of small-study effects or because the number of participants was below 400.CNS adverse events occurred in 52 studies, while 53 studies reported of absence of CNS adverse events. Overall, 187/3614 (5%) participants receiving ketamine and 122/2924 (4%) receiving control treatment experienced an adverse event (RR 1.2, 95% CI 0.95 to 1.4; high-quality evidence; 105 studies, 6538 participants). Ketamine reduced postoperative nausea and vomiting from 27% with placebo to 23% with ketamine (RR 0.88, 95% CI 0.81 to 0.96; the number needed to treat to prevent one episode of postoperative nausea and vomiting with perioperative intravenous ketamine administration was 24 (95% CI 16 to 54; high-quality evidence; 95 studies, 5965 participants).

AUTHORS' CONCLUSIONS

Perioperative intravenous ketamine probably reduces postoperative analgesic consumption and pain intensity. Results were consistent in different operation types or timing of ketamine administration, with larger and smaller studies, and by higher and lower pain intensity. CNS adverse events were little different with ketamine or control. Perioperative intravenous ketamine probably reduces postoperative nausea and vomiting by a small extent, of arguable clinical relevance.

Effects of Ketamine on Postoperative Pain After Remifentanil-Based Anesthesia for Major and Minor Surgery in Adults: A Systematic Review and Meta-Analysis

Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has been postulated as an adjuvant analgesic for preventing remifentanil-induced hyperalgesia after surgery. This systematic review and meta-analysis aims to assess the effectiveness of ketamine [racemic mixture and S-(+)-ketamine] in reducing morphine consumption and pain intensity scores after remifentanil-based general anesthesia. We performed a literature search of the PubMed, Web of Science, Scopus, Cochrane, and EMBASE databases in June 2017 and selected randomized controlled trials using predefined inclusion and exclusion criteria. To minimize confounding and heterogeneity, studies of NMDA receptor antagonists other than ketamine were excluded and the selected studies were grouped into those assessing minor or major surgery. Methodological quality was evaluated with the PEDro and JADA scales. The data were extracted and meta-analyses were performed where possible. Twelve RCTs involving 156 adults who underwent minor surgery and 413 adults who underwent major surgery were included in the meta-analysis. When used as an adjuvant to morphine, ketamine reduced postoperative morphine consumption in the first 24 h and postoperative pain intensity in the first 2 h in the minor and major surgery groups. It was also associated with significantly reduced pain intensity in the first 24 h in the minor surgery group. Time to the first rescue analgesia was longer in patients who received ketamine and underwent major surgery. No significant differences in the incidence of ketamine-related adverse effects were observed among patients in the intervention group and controls. This systematic review and meta-analysis show that low-dose (≤0.5 mg/kg for iv bolus or ≤5 μg/kg/min for iv perfusion) of ketamine reduces postoperative morphine consumption and pain intensity without increasing the incidence of adverse effects.

Ketamine does not enhance the quality of recovery following laparoscopic cholecystectomy: a randomized controlled trial

BACKGROUND

Ketamine has been used as part of the multimodal analgesia technique in the acute perioperative period. The effect of perioperative intravenous small-dose ketamine on the quality of recovery from the patient point-of-view has not been assessed. We hypothesized that low-dose ketamine would enhance recovery following laparoscopic cholecystectomy under total intravenous anesthesia.

METHODS

One hundred thirty five patients undergoing laparoscopic cholecystectomy were enrolled in this randomized, double-blind placebo-controlled trial. Subjects were randomly assigned to one of three groups: saline, ketamine 0.2 mg/kg, or ketamine 0.4 mg/kg immediately following the induction of anesthesia and before skin incision. The primary endpoint was assessed using the Quality of Recovery Questionnaire (QoR-40), a 40-item quality of recovery scoring system. In addition, early clinical recovery variables, such as time to eye opening, occurrence of nausea and vomiting, pain score, analgesic use, and length of PACU stay were assessed.

RESULTS

No differences were detected in the total or individual dimension scores of the QoR-40 questionnaire. The incidence of nausea, vomiting, and other complications did not differ among the three groups.

CONCLUSIONS

Small doses of ketamine do not improve the quality of recovery after remifentanil-based anesthesia for laparoscopic cholecystectomy.

Intra- and postoperative low-dose ketamine for adolescent idiopathic scoliosis surgery: a randomized controlled trial

BACKGROUND

In this randomized controlled trial, we examined whether intra- and postoperative infusion of low-dose ketamine decreased postoperative morphine requirement and morphine-related adverse effects as nausea and vomiting after scoliosis surgery.

METHODS

After IRB approval and informed consent, 36 patients, aged 10-19 years, undergoing posterior correction surgery for adolescent idiopathic scoliosis, were randomly allocated into two groups: intra- and postoperative ketamine infusion at a rate of 2 μg/kg/min until 48 h after surgery (ketamine group, n = 17) or infusion of an equal volume of saline (placebo group, n = 19). All patients were administered total intravenous anesthesia with propofol and remifentanil during surgery and intravenous morphine using a patient-controlled analgesia device after surgery. The primary outcome was cumulative morphine consumption in the initial 48 h after surgery. Pain scores (Numerical Rating Scale, NRS, 0-10), sedation scales, incidence of postoperative nausea and vomiting (PONV), and antiemetic consumption were recorded by nurses blinded to the study protocol for 48 h after surgery.

RESULTS

Patient characteristics did not differ between the two groups. Cumulative morphine consumption for 48 h after surgery was significantly lower in the ketamine group compared to the placebo group (0.89 ± 0.08 mg/kg vs. 1.16 ± 0.07 mg/kg, 95% confidence interval for difference between the means, 0.03-0.48 mg/kg, P = 0.019). NRS pain, sedation scales, and incidence of PONV did not differ between the two groups. Antiemetic consumption was significantly smaller in ketamine group.

CONCLUSIONS

Intra- and postoperative infusion of low-dose ketamine reduced cumulative morphine consumption and antiemetic requirement for 48 h after surgery.

Ketamine in outpatient arthroscopic shoulder surgery: Effects on postoperative pain, hemodynamic stability and process times

Background

Pain after arthroscopic shoulder surgery is often severe, and establishing a pain treatment regimen that does not delay discharge can be challenging. The reported ability of ketamine to prevent opioid-induced hyperalgesia has not been investigated in this particular setting.

Methods

300 adult patients scheduled for shoulder arthroscopy under general anesthesia were recruited for this observational clinical trial and were allotted to either receive 1mg/kg IV bolus of ketamine before surgery (ketamine group, KG) or to a control group (CG) without ketamine. NRS pain scores were obtained on the operative day and on postoperative days 1 and 2 and compared between groups. Secondary variables were blood pressure, heart rate, process times, satisfaction with the anesthetic and unwanted effects.

Results

Pain severity did not differ significantly between the groups at any time. Propofol injection rate and cumulative dose were higher in the KG. Heart rates and blood pressures were similar. Time to emergence and time in PACU were longer and vomiting was more frequent in patients given ketamine.

Conclusion

Preoperative low-dose ketamine added to a general anesthetic does not reduce perioperative pain after outpatient shoulder arthroscopy. It increases procedural times and the incidence of PONV.

Preoperative low-dose ketamine has no preemptive analgesic effect in opioid-naïve patients undergoing colon surgery when nitrous oxide is used - a randomized study

BACKGROUND

The analgesic properties of ketamine are associated with its non-competitive antagonism of the N-methyl-D-aspartate receptor; these receptors exhibit an excitatory function on pain transmission and this binding seems to inhibit or reverse the central sensitization of pain. In the literature, the value of this anesthetic for preemptive analgesia in the control of postoperative pain is uncertain. The objective of this study was to ascertain whether preoperative low-dose ketamine reduces postoperative pain and morphine consumption in adults undergoing colon surgery.

METHODS

In a double-blind, randomized trial, 48 patients were studied. Patients in the ketamine group received 0.5 mg/kg intravenous ketamine before surgical incision, while the control group received normal saline. The postoperative analgesia was achieved with a continuous infusion of morphine at 0.015 mg∙kg-¹∙h-¹ with the possibility of 0.02 mg/kg bolus every 10 min. Pain was assessed using the Visual Analog Scale (VAS), morphine consumption, and hemodynamic parameters at 0, 1, 2, 4, 8, 12, 16, and 24 hours postoperatively. We quantified times to rescue analgesic (Paracetamol), adverse effects and patient satisfaction.

RESULTS

No significant differences were observed in VAS scores between groups (P>0.05), except at 4 hours postoperatively (P=0.040). There were no differences in cumulative consumption of morphine at any time point (P>0.05). We found no significant differences in incremental postoperative doses of morphine consumption in bolus, except at 12 h (P =0.013) and 24 h (P =0.002). The time to first required rescue analgesia was 70 ± 15.491 min in the ketamine group and 44 ± 19.494 min in the control (P>0.05). There were no differences in hemodynamic parameters or patient satisfaction (P>0.05).

CONCLUSIONS

Preoperative low-dose-ketamine did not show a preemptive analgesic effect or efficacy as an adjuvant for decreasing opioid requirements for postoperative pain in patients receiving intravenous analgesia with morphine after colon surgery.

Interaction between postoperative shivering and hyperalgesia caused by high-dose remifentanil

BACKGROUND

High-dose remifentanil-based anesthesia is associated with opioid-induced hyperalgesia (OIH) and postanesthetic shivering (PAS). These effects can be prevented by N-methyl-d-aspartate (NMDA) receptor antagonists. This study aimed to investigate correlations between OIH and PAS caused by high-dose remifentanil and the effects of low-dose ketamine on OIH and PAS.

METHODS

Seventy-five patients scheduled for single-port laparoscopic gynecologic surgery were randomly allocated into three groups, each of which received intraoperative remifentanil: group L at 0.1 µg/kg/min; group H at 0.3 µg/kg/min; and group HK at 0.3 µg/kg/min plus 0.25 mg/kg ketamine just before incision, followed by a continuous infusion of 5 µg/kg/min ketamine until skin closure.

RESULTS

PAS, postoperative tactile pain threshold, and the extent of hyperalgesia in group H were significantly different (P < 0.05) than in the other two groups. PAS was significantly correlated with OIH, including mechanically evoked pain such as postoperative tactile pain threshold (r = -0.529, P = 0.01) (r = -0.458, P = 0.021) and the extent of hyperalgesia (r = 0.537, P = 0.002) (r = 0.384, P = 0.031), respectively, in group H and group HK. Notably, both groups were treated with high-dose remifentanil. Tympanic membrane temperature, time to first postoperative analgesic requirement, postoperative pain scores, analgesic consumption, and cumulative patient-controlled analgesia volume containing morphine were comparable in all three groups.

CONCLUSIONS

OIH, including the enhanced perception of pain, and PAS were both associated with high-dose remifentanil, were significantly correlated and were attenuated by a low dose of ketamine. This suggests that a common mechanism in part mediated through activation of the central glutamatergic system (e.g., NMDA receptors), underlies the two effects caused by high doses of remifentanil.

Effect of timing of morphine administration during propofol - remifentanil anesthesia on the requirements of post-operative analgesia

Background

An important concern of intra-operative infusion of remifentanil is the possible development of acute opioid tolerance, which manifests as an increased postoperative analgesia requirement. We have examined the effect of the timing of intra operative morphine administration on the need for morphine consumption for pain control during the first 24 hours after operation.

Methods

Sixty adult patients scheduled for elective open unilateral nephrolithotomy surgery were recruited for this prospective randomized double-blind study. Anesthesia was induced with 0.03 mg/kg midazolam, 1 µg/kg remifentanil, and 1.5-2 mg/kg propofol. Anesthesia was maintained with 100 µg/kg/min propofol, and 0.25 µg/kg/min remifentanil. Both groups received 0.1 mg/kg morphine intravenously at 2 different times; in the first group (group E) immediately after intubation and in the second group (group L) 20-30 min before the anticipated end of operation.

Results

There was no difference in pain scores at awakening, the amount of morphine given to the 2 groups for pain control, or the time to discharge from PACU between the 2 groups. The pain scores at admission to ward and at every 4 hours thereafter, until 24 hours, were not significantly different between the 2 groups. The cumulative amount of the first 24 hours morphine consumption in the ward in E group was 28.2 ± 20.1 mg and 26.5 ± 15 mg in L group, respectively (P = 0.71).

Conclusions

Early intra-operative administration of morphine compared to that of morphine in the end of surgery did not affect postoperative morphine consumption and pain scores during the first 24 hours after surgery for open nephrolithotomy. Newer pharmacologic interventions for prevention of acute tolerance of opioids seems rational (Clinical trial registration No. ACTRN: 12609000570280).

Ketamine and remifentanil interactions on the sevoflurane minimum alveolar concentration and acute opioid tolerance in the rat

BACKGROUND

Ketamine is used at low doses for its analgesic and antihyperalgesic properties when combined with opioids but also when opioid-induced hyperalgesia and tolerance appear. In this study we determined the interaction of ketamine and remifentanil on the minimum alveolar concentration (MAC) of sevoflurane in rats and to determine whether ketamine may block acute opioid tolerance (AOT).

METHODS

Male Wistar rats were anesthetized with sevoflurane, and the MAC was determined before and after ketamine administration (10, 20, 40, and 80 mg kg(-1) or saline) alone or combined with remifentanil (120 and 240 μg kg(-1) h(-1), low and high doses, respectively). One additional group received the lowest ketamine dose after starting a remifentanil infusion. Finally, naloxone was administered to determine the potential action of ketamine on opioid receptors. MAC was determined from intratracheal gas samples, and tail clamping was used as a supramaximal stimulus. End-tidal anesthetic concentrations were assayed using a side stream gas analyzer. Statistical analysis was performed with an analysis of variance.

RESULTS

Ketamine and remifentanil dose-dependently reduced the MAC. Adding the low dose of remifentanil to ketamine did not improve the MAC reduction, whereas the high dose of remifentanil enhanced ketamine reduction in a subadditive fashion. Nevertheless, ketamine was unable to block the development of AOT to remifentanil at either dose. Finally, naloxone blocked the MAC reduction produced by ketamine.

CONCLUSIONS

A subadditive effect between ketamine and remifentanil was found on the sevoflurane MAC reduction rats. In addition, ketamine was unable to block AOT. The clinical relevance of these findings should be elucidated in future studies to reduce anesthetic requirements.

Effects of perioperative S (+) ketamine infusion added to multimodal analgesia in patients undergoing ambulatory haemorrhoidectomy

Background and objective

Perioperative low-dose ketamine has been useful for postoperative analgesia. In this study we wanted to assess the analgesic effect and possible side-effects of perioperative low-dose S (+) ketamine when added to a regime of non-opioid multimodal pain prophylaxis.

Methods

Seventy-seven patients scheduled for haemorrhoidectomy were enrolled in this randomized, double-blind, controlled study. They received oral paracetamol 1–2 g, total intravenous anaesthesia, intravenous 8 mg dexamethasone, 30 mg ketorolac and local infiltration with bupivacaine/epinephrine. Patients randomized to S (+) ketamine received an intravenous bolus dose of 0.35 mg kg−1 S (+) ketamine before start of surgery followed by continuous infusion of 5 μg kg−1 min−1 until 2 min after end of surgery. Patients in the placebo group got isotonic saline (bolus and infusion). BISTM monitoring was used. Pain intensity and side-effects were assessed by blinded nursing staff during PACU stay and by phone 1, 7 and 90 days after surgery.

Results

In patients randomized to S (+) ketamine emergence from anaesthesia was significantly longer (13.1 min vs. 9.3 min; p < 0.001). BIS values were significantly higher during anaesthesia (maximal value during surgery: 62 vs. 57; p = 0.01) and when opening eyes (81 vs. 70, p < 0.001). Pain scores (NRS and VAS) did not differ significantly between groups.

Conclusions

The addition of perioperative S (+) ketamine for postoperative analgesia after haemorrhoidectomy on top of multimodal non-opioid pain prophylaxis does not seem to be warranted, due to delayed emergence and recovery, more side-effects, altered BIS readings and absence of additive analgesic effect.

The preemptive analgesic effect of ketorolac and propacetamol for adenotonsillectomy in pediatric patients

BACKGROUND

Both ketorolac and propacetamol are used postoperatively to control mild to moderate pain. This study compared the analgesic efficacy of ketorolac and propacetamol delivered either preoperatively or postoperatively, and assessed the preemptive analgesic effect of ketorolac and propacetamol for adenotonsillectomy.

METHODS

One hundred and two pediatric patients were divided randomly into four groups. The K1 and P1 groups received ketorolac 1 mg/kg or propacetamol 30 mg/kg after induction, respectively, whereas the K2 and P2 groups received each drug at the end of the operation, respectively. After adenotonsillectomy, we measured the NRS (Numerical Rating Scale), FPS (Faces Pain Scale) and OPS (Objective Pain scale) at 15, 30 and 60 min after arriving at the postanesthesia care unit.

RESULTS

There were no significant differences in the NRS, FPS and OPS between K1 and K2 and between P1 and P2 for 60 min after operation at the postanesthesia care unit.

CONCLUSIONS

These results suggest that both ketorolac (1 mg/kg) and propacetamol (30 mg/kg) have no preemptive analgesic effects during 1 hour after adenotonsillectomy.

[Remifentanil-based intraoperative anaesthesia and postoperative pain therapy. Is there an optimal treatment strategy?]

Remifentanil is a synthetic opioid derivate with an agonist activity at mu-opioid receptors. The pharmacokinetic profile differs from other synthetic opioids. Remifentanil is rapidly metabolised by unspecific blood and tissue esterases and the metabolites have almost no intrinsic activity. According to its unique pharmacokinetic profile, remifentanil-based anaesthesia might be associated with a high level of postoperative pain, therefore, an appropriate postoperative pain management is an import aspect. In addition, remifentanil withdrawal induces a compensatory up-regulation of secondary messenger pathways, inducing hyperalgesia. This review provides a comprehensive summary of basic and clinical research concerning the intraoperative use of remifentanil and postoperative pain therapy. The relative contribution of rapid degradation and withdrawal-induced hyperalgesia to postoperative pain will be discussed. In addition, this review attempts to identify potential clinical implications and treatment strategies.

The efficacy of intravenous or peritonsillar infiltration of ketamine for postoperative pain relief in children following adenotonsillectomy

BACKGROUND

A few previous studies have suggested the efficacy of i.v. ketamine for postoperative pain relief in children after adenotonsillectomy, but none has investigated the efficacy of peritonsillar infiltration of ketamine in these children.

METHODS

This randomized, placebo-controlled study evaluated the effects of peritonsillar infiltration of ketamine in children undergoing adenotonsillectomy. Ninety ASA I-II children were randomized three groups of 30 each. Group I received: 2 ml i.v. saline, group II received i.v. ketamine (0.5 mgxkg(-1)) and group III received a local peritonsillar infiltration of ketamine (0.5 mgxkg(-1)). All medications were 2 ml in volume which was applied 1 ml per tonsil 3 min prior to tonsillectomy. Modified Hannallah pain scale [observational pain scores (OPS)], nausea, vomiting, bleeding, rescue analgesia, sedation and Aldrete scores were recorded at first, 15th, 30th and 60th min postoperatively. Patients were interviewed on the day after surgery to assess the postoperative pain, nightmares, hallucinations, vomiting and bleeding.

RESULTS

Group I had higher OPS scores than group II and group III. Group II and group III had comparable scores, which were not statistically significant (P > 0.05). Group II had higher sedation score at 15th min (P = 0.015). Thirty-two children, 19 of whom were in group I had rescue analgesia in postanesthesia care unit (P < 0.05) and the time to first analgesic requirement was significantly shorter in group I than the other groups (P = 0.006). Group II and group III also had less pain than group I at home (P = 0.023).

CONCLUSIONS

Low dose ketamine given i.v. or by peritonsillar infiltration perioperatively provides efficient pain relief without side-effects in children undergoing adenotonsillectomy.

A comparison of four methods of analgesia in cats following ovariohysterectomy

OBJECTIVE

To evaluate the effectiveness of preoperative administration of oral carprofen, subcutaneous ketoprofen, and local nerve block with bupivacaine in preventing postoperative pain-associated behavior in cats after ovariohysterectomy.

ANIMALS

Fifty-two female intact cats. Materials and methods Cats received butorphanol (0.44 mg kg(-1) IM), carprofen (2.2 mg kg(-1) PO), ketoprofen (2.2 mg kg(-1) SQ), or bupivacaine infiltration block (1.1 mg kg(-1) SQ) before surgery. Cortisol and drug concentrations and visual analog scale (VAS) and interactive visual analog scale (IVAS) pain-associated behavior scores were measured 2 hours before and 0, 1, 2, 4, 8, 12, and 24 hours after ovariohysterectomy.

RESULTS

Cats receiving butorphanol had significantly increased IVAS scores 2 hours after surgery compared with baseline measurements. Cats receiving carprofen, ketoprofen, and bupivacaine had significant increases from baseline in VAS and IVAS scores 1 and 2 hours after surgery. VAS and IVAS scores for cats receiving bupivacaine were significantly greater 1 and 2 hours after surgery than for cats that received butorphanol. Cats receiving carprofen had significant increases in cortisol 1 hour after surgery and significant decreases 24 hours after surgery compared with baseline measurements.

CONCLUSIONS AND CLINICAL RELEVANCE

Preoperative carprofen and ketoprofen have effects on pain-associated behavior similar to butorphanol in cats undergoing ovariohysterectomy. Cats receiving bupivacaine blocks may require additional analgesics immediately after surgery.

Lack of a pre-emptive effect of low-dose ketamine on postoperative pain following oral surgery

PURPOSE

The aim of this study was to assess the effect of pre- vs postincisional low-dose iv ketamine on postoperative pain in outpatients scheduled for oral surgery under general anesthesia.

METHODS

Eighty-four patients were randomly assigned to receive intravenously saline before and after surgery in Group 1, ketamine 300 microg x kg(-1) iv before and saline after surgery in Group 2, saline before and ketamine 300 microg x kg(-1) iv after surgery in Group 3. Postoperative analgesia consisted of iv proparacetamol and ketoprofen. Rescue analgesia consisted of nalbuphine 200 microg x kg(-1) iv. Analgesia at home consisted of oral ketoprofen, and acetaminophen with codeine as rescue analgesia. A telephone interview was conducted on the first and second postoperative days.

RESULTS

There were no significant differences between groups with respect to pain scores, the number of patients requiring nalbuphine in the postanesthesia care unit (PACU), (36.7%, 38.7%, and 39.5% for Groups 1, 2, and 3 respectively), or nalbuphine consumption in the PACU (66.5 microg x kg(-1) +/- 16.8, 75.9 microg x kg(-1) +/- 17.5, 66.7 microg x kg(-1) +/- 21.6 for Groups 1, 2, and 3 respectively). The number of rescue analgesic tablets taken at home, and time to first request for rescue analgesia, sedation scores, or side-effects were similar amongst groups. No patient required nalbuphine in the ambulatory care unit.

CONCLUSIONS

There was no benefit to pre-emptive administration of ketamine 300 microg x kg(-1) iv whether administered pre- or postoperatively.

Comparison of oral and subcutaneous administration of buprenorphine and meloxicam for preemptive analgesia in cats undergoing ovariohysterectomy

OBJECTIVE

To compare the effectiveness of preoperative PO and SC administration of buprenorphine and meloxicam for prevention of postoperative pain-associated behaviors in cats undergoing ovariohysterectomy.

DESIGN

Randomized controlled study.

ANIMALS

51 female cats (4 to 60 months old; weight range, 1.41 to 4.73 kg [3.1 to 10.4 lb]).

PROCEDURE

Cats received 1 of 5 treatments at the time of anesthetic induction: buprenorphine PO (0.01 mg/kg [0.0045 mg/lb]; n = 10), buprenorphine SC (0.01 mg/kg; 10), meloxicam SC (0.3 mg/kg 10.14 mg/lb]; 10), meloxicam PO (0.3 mg/kg; 10), or 0.3 mL of sterile saline (0.9% NaCI) solution SC (control group; 11). Sedation scores and visual analog scale and interactive visual analog scale (IVAS) pain-associated behavior scores were assigned to each cat 2 hours before and at intervals until 20 hours after surgery.

RESULTS

Cats receiving meloxicam PO or SC had significantly lower IVAS scores (2.91 and 2.02, respectively), compared with IVAS scores for cats receiving buprenorphine PO (755). Pain-associated behavior scores for cats administered buprenorphine or meloxicam PO or SC preoperatively did not differ significantly from control group scores. Rescue analgesia was not required by any of the cats receiving meloxicam, whereas 3 of 10 cats receiving buprenorphine PO, 2 of 10 cats receiving buprenorphine SC, and 1 of 11 cats receiving the control treatment required rescue analgesia.

CONCLUSIONS AND CLINICAL RELEVANCE

On the basis of pain-associated behavior scores, cats receiving meloxicam PO or SC before ovariohysterectomy appeared to have less pain after surgery than those receiving buprenorphine PO preoperatively.