Preoperative Morphine Research Articles

Increased Duration of Total Hip and Total Knee Arthroplasty Surgery Increases the Risk of Post-Operative Urinary Retention: A Retrospective Cohort Study.

Background: Post-operative urinary retention (POUR) is a common complication following total hip arthroplasty (THA) and total knee arthroplasty (TKA). Spinal anaesthetic has been associated with an increased risk of POUR, whilst other risk factors remain unclear. This study aims to identify modifiable and non-modifiable risk factors of POUR for THA and TKA patients. Methods: A single-centre retrospective cohort study of patients admitted to our hospital over the course of 6 weeks from September to October 2021 for a THA or TKA. All patients who underwent elective THA/TKA were included, and trauma cases were excluded. Results: Ninety-two consecutive patients were included in this study. The overall rate of POUR was 17%. A shorter operative duration resulted in a reduced risk of POUR (median duration of non-retention patients, 88 min vs. 100 min POUR patients; odds ratio, 0.97; 95% CI, 0.95-0.99, p = 0.018). The median bladder volume of patients with urinary retention at the point of diagnosis was 614 mL (range, 298-999 mL). The arthroplasty type, anaesthetic technique, pre-operative morphine use, body mass index, age, cardiovascular disease, and renal disease were found to have no significant association with POUR. Conclusions: A reduced operative time of arthroplasty surgery is associated with a decreased risk of POUR. Patients with a prolonged operative time should have an increased frequency of micturition monitoring in the immediate post-operative period.

Spinal Anesthesia Prior to Laparoscopic Hysterectomy Resulted in Decreased Postoperative Pain and Opioid Use.

To determine if a pre-operative morphine/bupivacaine spinal injection prior to laparoscopic hysterectomy reduced postoperative pain and resulted in less opioid consumption during the hospital stay. A retrospective cohort study (Canadian Task Force Classification II-2) was conducted at a single institution regional referral center (community hospital) in North Carolina. Three hundred nineteen patients met criteria for inclusion: 192 received spinal anesthesia and 127 did not. Baseline demographics were similar between the two groups. Median pain scores were significantly lower in the treatment than the control group on day of surgery (DOS) (2 vs. 6; P < 0.001) and postoperative day 1 (POD1) (2 vs. 4; P < 0.001). Primary outcomes were pain scores on DOS and POD1 and inpatient opioid use. Pain scores were obtained using the 0 to 10 Numerical Rating Scale. Opioids were converted to oral morphine milliequivalents (OME). Median opioid use was also significantly lower in the treatment than the control group on DOS (0 vs. 15.00 OME; P < 0.001) and POD1 (0 vs. 7.5 OME; P < 0.001). Median length of stay between the groups was not significantly different. Pre-operative morphine spinal injection for laparoscopic hysterectomy led to significantly lower pain scores and inpatient opioid consumption. Pre-operative spinal anesthesia for benign laparoscopic hysterectomy appears helpful for enhancing the postoperative experience.

Adverse Effects Associated with Patient-Controlled Analgesia with Ketamine Combined with Opioids and Ketamine Infusion with PCA Bolus in Postoperative Spine Patients: A Retrospective Review.

ObjectiveThere has been increasing use of ketamine at subanesthetic doses as an adjunct to opioids in perioperative pain management. There are several known adverse drug effects (ADEs) associated with ketamine. However, the incidence of ADEs with ketamine infusions with patient-controlled analgesia (PCA) boluses compared with combined opioid and ketamine PCAs is not well described. The objectives of this study were to compare the incidence and type of ADEs in postoperative spine surgery patients on ketamine infusions with as-needed PCA boluses to patients on combined opioid and ketamine PCAs.MethodsThe medical records of patients who underwent spine surgery between March 2016 and March 2020 who were postoperatively treated with a ketamine infusion and as-needed PCA boluses and parenteral opioids or treated with a combined opioid and ketamine PCA were reviewed. Perioperative information including patient characteristics and preoperative morphine equivalent daily dose (MEDD) were collected. Patient charts were reviewed for ADEs including psychological and neurological side effects, nausea, and new-onset tachycardia.ResultsA total of 315 patients met the inclusion criteria and were included in the final analysis. Of these patients, 121 experienced at least one ADE (38%). Sixteen of the 68 ketamine infusion with PCA bolus patients (24%), 77 of the 203 hydromorphone and ketamine patients (38%), and 28 of the 44 morphine and ketamine patients (64%) experienced an ADE [p<0.01]. In patients with preoperative MEDD ≤ 90, nausea was the only ADE that differed significantly among the three groups.ConclusionThis retrospective analysis suggests that postoperative spine patients treated with a ketamine infusion with as-needed PCA boluses and parenteral opioids were associated with fewer ADEs when compared to an intravenous combined opioid and ketamine PCA. In patients with preoperative MEDD ≤ 90, nausea with and without emesis was the only ADE that showed statistically significant difference amongst the three groups.

P94. Preoperative opioid use poorly correlates with mental health in adult spinal deformity: Time to rethink foregone conclusions

<h3>BACKGROUND CONTEXT</h3> Preoperative opioid consumption, poor mental health, and lower socioeconomic status are each associated with worse surgical outcomes for adult spinal deformity (ASD). Little data exits evaluating preoperative morphine milligram equivalent (MME) consumption and preoperative mental health, social function, and socioeconomic status in ASD. <h3>PURPOSE</h3> Evaluate the correlations between preoperative daily MME consumption and preoperative depression, anxiety, mental health scores, and socioeconomic status for ASD patients prior to receiving reconstructive ASD surgery. We hypothesized that preoperative MME consumption correlates with preoperative depression, anxiety, poor mental health, poor social function, and poor socioeconomic status in ASD. <h3>STUDY DESIGN/SETTING</h3> Preoperative analysis of ASD patients prospectively enrolled into a multicenter study. <h3>PATIENT SAMPLE</h3> ASD patients prospectively enrolled into multicenter study. <h3>OUTCOME MEASURES</h3> Numeric rating scale (NRS) back and leg pain, Scoliosis Research Society-22r questionnaire (SRS-22r), Edmonton Frailty Index (EFI score), grip strength, Veterans Rand Health Questionnaire (VR-12), Oswestry Disability Index (ODI), daily morphine milligram equivalent consumption (MME), PROMIS-Pain Interference (PROMIS-PI), PROMIS-Physical Function (PROMIS-PF), PROMIS-Depression (DEP), PROMIS-Anxiety (ANX), PROMIS-Satisfaction with Social Roles (SR) and PROMIS-Satisfaction with Discretionary Social Activities (SDA) computer adaptive tests (CATs), Area Deprivation Index (ADI) scores. <h3>METHODS</h3> From 2018-2020, ASD patients were prospectively enrolled into a multicenter study. Preoperative MME was calculated. Preoperative PROMIS-DEP, PROMIS-ANX, PROMIS=SR, PROMIS-SDA, PROMIS-PI and PF, SRS-22r total and domain scores, and VR-12 mental component summary (MCS) were calculated. ADI scores were collected to assess socioeconomic status, as previously described. MME data were log transformed and two-tailed Pearson correlation coefficients calculated. Correlation strengths were interpreted according to Cohen. Confidence intervals were created with 1,000 sample bootstrapping. <h3>RESULTS</h3> A total of 207/207 patients enrolled were evaluated; mean age 61 years (18-81). Preoperative opioid consumption was reported in 38% patients (n=78; mean preoperative MME 22.5 mg, range 1-420 mg). Preoperative MME did not correlate with PROMIS-ANX (p=0.07) and did not correlate with socioeconomic status (ADI; p=0.37). Preoperative MME showed small correlations with PROMIS-DEP (r=0.2, p=0.01), VR-12 MCS (r=-.2, p=0.002), and SRS-Mental Health (r=-0.2, p=0.005). Preoperative MME showed moderate correlations with PROMIS-PI (r=0.4, p<0.0001), PROMIS-PF (r=-0.4, p<0.0001), SRS-Pain (r=-0.5, p<0.0001), SRS-Function (r=-0.4, p<0.0001), PROMIS-SR (r=-0.3, p<0.0001) and PROMIS-SSA (r=-0.4, p<0.0001). <h3>CONCLUSIONS</h3> Prospective evaluation of 207 ASD patients demonstrated minimal to no correlations between preoperative MME consumption and preoperative anxiety, depression or low socioeconomic status. Preoperative MME consumption demonstrated moderate correlations with preoperative pain, physical function, and social function scores. The negative impacts of opioid consumption on physical measures are likely independent of psychosocial variables in ASD. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Pain Scores and Opioid Use Following Preoperative Spinal Anesthesia for Benign Laparoscopic Hysterectomy

Study Objective To determine if spinal anesthesia prior to benign laparoscopic hysterectomy was associated with less pain and opioid use postoperatively. Design Retrospective cohort study. Setting Single institution regional referral center. Patients or Participants Patients were included who received the Enhanced Recovery After Surgery (ERAS) protocol for benign laparoscopic hysterectomies in 2019. Patients undergoing additional non-gynecological surgeries, surgery for malignancy, had procedures converted to open, or who received TAP blocks were excluded, as were patients with chronic opioid exposure. Interventions The two cohorts included the treatment group who received preoperative spinal anesthesia (bupivacaine and morphine), and the control group who did not receive spinal anesthesia. All other ERAS components remained the same. Measurements and Main Results Primary outcomes were day of surgery (DOS) and postoperative day one (POD1) pain scores, opioid use inpatient and 60 days postoperatively. Pain scores were obtained using the 0 to 10 Numerical Rating Scale. Opioids were converted to oral morphine milliequivalents (OME). 200 patients were randomly selected from each cohort: 100 received spinal anesthesia, and 100 did not. Baseline demographics were similar between the two groups. Mean pain scores were significantly lower in the treatment than the control group on DOS (2.78 vs. 5.77, p Conclusion Preoperative morphine spinal injection for laparoscopic hysterectomy led to significantly lower pain scores and inpatient opioid consumption. Preoperative spinal anesthesia for benign laparoscopic hysterectomy may be helpful for enhancing the immediate postoperative experience.

Comparison of the Stopping Opioids after Surgery (SOS) score to preoperative morphine milligram equivalents (MME) for prediction of opioid prescribing after lumbar spine surgery

BACKGROUND CONTEXTReliable estimation of the likelihood for prolonged postoperative opioid use may aid targeted interventions for high-risk patients. Previous studies have recommended differing methodologies for prediction of sustained postoperative opioid use. PURPOSETo compare the performance of the Stopping Opioids after Surgery (SOS) score and preoperative morphine milligram equivalents (MME) for postoperative opioid prescription exposure in a contemporary cohort of lumbar surgery patients. PATIENT SAMPLEAdult patients undergoing posterior decompression with or without fusion for degenerative lumbar conditions between January 31, 2016 and May 31, 2019. STUDY DESIGN/SETTINGRetrospective review at two academic medical centers and three community hospitals. OUTCOME MEASURESThe primary outcome was sustained postoperative prescription opioid exposure at 3 months and 6 months. Reoperations and readmissions were considered secondarily. METHODSThe Stopping Opioids after Surgery score and MME were assigned to patients based on data from their preoperative surgical evaluation. Performance for both measures was assessed for all outcomes by discrimination, including c-statistic and receiver-operating curve analysis. Calibration of the low, medium and high-risk strata with the observed rates of postoperative adverse events were examined. RESULTSOverall, 4,165 patients were included in this study. Preoperative prevalence of prescription opioid use was 31%. Rates of postoperative opioid prescriptions at 3 months and 6 months, were 3.3% (n=136) and 1.5% (n=61). The c-statistics of preoperative oral MME and SOS score for 3-month sustained opioid prescriptions were 0.64 and 0.78, respectively. The c-statistics of preoperative oral MME and SOS score for 6-month sustained opioid prescriptions were 0.64 and 0.82, respectively. C-statistics of preoperative oral MME and SOS score were much lower for reoperation and readmission, although SOS score outperformed MME for both outcomes. CONCLUSIONSThe SOS score clinically outperformed oral MME as a predictive measure for outcomes following lumbar spine surgery. The SOS score may be valuable for identifying individuals at high-risk for sustained prescription opioid use and associated adverse events following spine surgery.

Prescription Patterns and Risk Factors for Prolonged Opioid Dependence in Elective Anterior Cruciate Ligament Reconstruction in a Military Population.

Background:Limited data are available regarding excessive opioid prescribing in the perioperative period after routine orthopaedic procedures in US military personnel.Purpose:To examine the demographic profile of the patients receiving these medications and to identify potential risk factors for prolonged opioid use after anterior cruciate ligament reconstruction (ACLR) in the active duty military population.Study Design:Case-control study; Level of evidence, 3.Methods:The Military Analysis and Reporting Tool (M2) was used to search the Military Health System Data Repository (MDR) for patients undergoing ACLR from 2012 through 2015 and specifically for active duty personnel with an arthroscopically assisted ACLR (Current Procedural Terminology [CPT] code 29888). Complete opioid prescription filling history was also obtained. This study had 2 primary outcomes: (1) use of opiate analgesics more than 90 days after surgery, representing prolonged opiate prescriptions, and (2) high levels of postoperative opiate use, defined as having filled prescriptions accounting for greater than the 95th percentile of morphine equivalents for patients in the study cohort. Data were analyzed via multivariate regression analysis to identify potential associations with the primary outcomes.Results:A total of 9474 patients met the inclusion criteria. Median patient age was 27 years, and the sample included 1316 (14%) female and 8158 (86%) male patients. A total of 66 (0.7%) patients had a preoperative diagnosis for substance abuse; 2656 (28%) patients continued to receive opioid prescriptions more than 90 days after surgery, and 502 (5%) patients were in the top 95th percentile of all opioid users within the study cohort. Total preoperative morphine equivalents per day and total perioperative morphine equivalents per day were highly important risk factors for both outcomes, although other demographic factors such as race, sex, and age may play minor roles.Conclusion:We identified total preoperative morphine equivalents, total perioperative morphine equivalents, sex, and race as potential predictors of prolonged opioid use after ACLR. This information may prove useful in developing a predictive model to identify at-risk patients before surgery. This could help mitigate future misuse or abuse and improve preoperative patient counseling regarding pain management expectations.

Can Predictive Modeling Tools Identify Patients at High Risk of Prolonged Opioid Use After ACL Reconstruction?

Can Predictive Modeling Tools Identify Patients at High Risk of Prolonged Opioid Use After ACL Reconstruction?

Is There a Preoperative Morphine Equianalgesic Dose that Predicts Ability to Achieve a Clinically Meaningful Improvement Following Spine Surgery?

Preoperative opioid use is widespread and associated with worse patient-reported outcomes following spine surgery. To calculate a threshold preoperative morphine equianalgesic (MEA) dose beyond which patients are less likely to achieve the minimum clinically important difference (MCID) following elective surgery for degenerative spine disease. The study included 543 cervical and 1293 lumbar patients. Neck Disability Index and Oswestry Disability Index scores were collected at baseline and 12 mo postoperatively. Preoperative MEA doses were calculated retrospectively. Multivariate logistic regression was then performed to determine the relationship between MEA dose and the odds of achieving MCID. As a part of this regression, Bayesian inference and Markov Chain Monte Carlo methods were used to estimate the values of inflection points (or "thresholds") in MEA. Overall, 1020 (55.5%) patients used preoperative opioids. A total of 50.3% of cervical and 61.9% of lumbar patients achieved MCID. The final logistic regression model demonstrated that MCID achievement decreased significantly when mean preoperative MEA dose exceeded 47.8 mg/d, with a 95% credible interval of 29.0 to 60.0 mg/d. Minimum and maximum MEA doses exist, between which increasing opioid dose is associated with decreased ability to achieve clinically meaningful improvement following spine surgery. Patients with preoperative MEA dose exceeding 29 mg/d, the lower limit of the 95% credible interval for the mean MEA dose above which patients exhibit significantly decreased achievement of MCID, may be considered for preoperative opioid weaning.

Evaluation of Two Protocols for Analgesia during Total Unilateral Mastectomy in Bitches

Background: Proper evaluation of pain is essential to select effective anesthetic protocols in surgical procedures in animals. Pain assessment can be accomplished during the perioperative period by measuring several physiological parameters, such as heart and respiratory rates. Measuring serum levels of cortisol and glucose is one of the most commonly used methods to assess the effectiveness of protocols for pain control. The aim of this study was to compare two analgesic protocols in dogs undergoing unilateral total mastectomy, a surgery that can cause moderate-to-severe pain in dogs. Materials, Methods &amp; Results: Eighteen female dogs seen at the Veterinary Hospital of the University of Southern Santa Catarina, Brazil, were recruited for this study, without stratification by breed and age, except for brachycephalic breeds. The animals were divided into two groups: 1) FLK group, in which the animals received preoperative ketamine (5 mg/ kg, IM) and midazolam (0.3 mg/kg, IM), an IV bolus of fentanyl (0.004 mg/kg), lidocaine (2 mg/kg) and ketamine (0.5 mg/kg), and then a combination of fentanyl (0.008 mg/kg/h), ketamine (0.6 mg/kg/h) and lidocaine (2 mg/kg/h) diluted in normal saline solution were infused at a rate of 10 mL/kg/h until the end of the surgical procedure; 2) AM group, in which the animals received preoperative morphine (0.5 mg/kg, IM) and acepromazine (0.05 mg/kg, IM). In both groups, anesthesia was induced by using propofol (6 mg/kg, IV) and maintained with isoflurane. Blood samples were collected by jugular venipuncture (4 mL) in the preoperative and postoperative periods to evaluate serum levels of cortisol and glucose. Statistical analysis was carried out using the two-way analysis of variance (ANOVA) for repeated measures, followed by the Tukey test (P &lt; 0.05). Cortisol levels showed no significant difference between pre- and postoperative periods. Glucose levels showed a significant difference between pre- and postoperative periods in the AM group (P = 0.001). The respiratory rate showed a significant difference between groups at 10 (T10) min after induction (P &lt; 0.001). Discussion: In this study, 67% of the experimental animals were mixed-breed dogs. The average weight was 16.9 ± 10.1 kg. The most frequent age group seen at the Veterinary Hospital was 8-10 years, which is in accordance with other published studies on female dogs with mean age of 10 years. The significant difference in the respiratory rate at T10 can be explained by the respiratory depression caused by a bolus administration of fentanyl in the FLK group. Both protocols were similar in this study; however, higher values of cortisol and glucose, even above the physiological reference values, were observed in the AM group as compared to the FLK group. These higher values must be taken into consideration due to their clinical importance, given that consequences of stress include several deleterious effects, such as immunosuppression, delayed wound healing, and acceleration of disease processes. Findings from this study indicate that the use of a multimodal analgesia protocol, such as the one used in the FLK group, is probably the best alternative for patients submitted to unilateral total mastectomy.

228 - What, If Any, Preoperative Morphine Equianalgesic Dose Predicts Ability to Achieve a Clinically Meaningful Improvement following Spine Surgery?

BACKGROUND CONTEXT: Preoperative opioid use is widespread and associated with worse patient-reported outcomes following spine surgery.

Preoperative Oral Morphine and Sub-Anesthetic Ketamine Co-Administration Reduce Acute Post-Mastectomy Pain

Objectives: To assess the analgesic efficacy and tolerability of co-administration of pre-emptive single oral dose of sustained release morphine and sub- anesthetic ketamine infusion for modified radical mastectomy (MRM) with axillary evacuation. Methods: Sixty four adult female patients scheduled for MRM were divided to two groups, morphine group (n=32) received preoperative oral sustained release morphine tablet, 30 mg and placebo group (n=32) received placebo tablet. Both groups received preoperative ketamine bolus, 0.5 mg/kg followed by continuous infusion 0.1 mg/kg/h for 24 h postoperatively. VAS pain score, time to first analgesic request, 24 h analgesic consumption were reported. Results: The mean VAS pain score during movement was significantly decreased in morphine group in comparison to placebo group from 2 h till 72 h postoperatively, 2 h (2.87 ± 1.0 vs. 4.53 ± 1.67) mean difference (-1.67) (95% CI)-(2.38-0.95), 72 h (1.20 ± 0.76 vs. 1.83 ± 0.91) mean difference (-0.63) (95% CI)-(1.07-0.20) while the mean VAS pain score during rest was significantly decreased in morphine group in comparison to placebo group from 2 h till 24 h postoperatively, 2 h (2.03 ± 0.85 vs. 3.47 ± 0.93) mean difference (-1.33) (95% CI)-(1.78-0.90), 24 h (1.40 ± 0.72 vs. 1.77 ± 0.68) mean difference (-0.37) (95% CI)-(0.73-0.01). The median (IQ) time to first analgesic request was significantly delayed in morphine group in comparison to placebo group, 11.8 (9.7:14.2) h vs. 2.3 (2.1:2.5) h, (P<0.001). The number (percentage) of patients required paracetamol in the first postoperative 24 h was significantly lower in morphine group in comparison to placebo group, 10 (33%) vs. 30 (100 %) (P<0.001). Conclusion: Analgesic technique based on pre-emptive sustained release oral morphine and perioperative infusion of sub-anesthetic dose of ketamine provides satisfactory analgesia for patients undergoing MRM.

Preoperative Slow-Release Morphine Reduces Need of Postoperative Analgesics and Shortens Hospital Stay in Laparoscopic Gastric Bypass.

As most bariatric procedures are performed by laparoscopy, hospital stay is exceptionally short, despite the habitus of patients and the rather extensive intra-abdominal surgery. To facilitate postoperative mobilization, most patients are given repeated single doses of morphine, a drug with several side effects. We aimed to evaluate the effect of preoperative treatment with a tablet of slow-release morphine (SRM) onpostoperative analgesic consumption and length of stay (LOS) in laparoscopic gastric bypass (LGBP). The SRM group (244 patients) was retrospectively compared to a control group (197 patients) concerning postoperative pain management and hospital stay by studying medical charts and data from Scandinavian Obesity Surgery Registry (SOReg). Patients in the SRM group needed significantly less analgesics during days 0, 1, and 2 postoperatively, morphine 10.7 vs. 13.6mg, 10.2 vs. 13.9mg, and 1.1 vs. 3.6mg, respectively, p < 0.05, as well as acetaminophen, p < 0.05. According to a subgroup analysis, 20mg of SRM was needed to obtain these effects. In addition, SRM patients had shorter hospital stay (2.3 vs. 3.5days, p < 0.05) than the control group. No negative side effects were seen. Preoperatively administered slow-release morphine significantly reduced the need for postoperative analgesics and shortened hospital stay, without side effects or other complications. At our department, the studied regime is now routinely used in all bariatric surgery and we have started to use the concept in other groups of surgical patients.

Preoperative opioid use and its association with perioperative opioid demand and postoperative opioid independence in patients undergoing spine surgery.

Prospective cohort. To assess whether preoperative opioid use is associated with increased perioperative opioid demand and postoperative opioid independence in patients undergoing spine surgery. Previous work has demonstrated increased opioid requirements during the intraoperative and immediate postoperative period in patients with high levels of preoperative opioid use. Despite this, they remain a common agent class used for the management of pain in patients prior to spine surgery. A total of 583 patients were included. Self-reported daily opioid consumption was obtained preoperatively and converted into morphine equivalent amounts and opioid use was recorded at the 12-month postoperative time. Intraoperative and immediate postoperative opioid demand was calculated. Linear regression analyses for intraoperative and immediate postoperative opioid demand while logistic regression analyses for opioid independence at 12 months including relevant covariates such as depression and anxiety were performed. The median preoperative morphine equivalent amount for the cohort was 8.75 mg, with 55% of patients reporting some degree of opioid use. Younger age, more invasive surgery, anxiety, and primary surgery were significantly associated with increased intraoperative opioid demand (P < 0.05). Younger age, anxiety, and greater preoperative opioid use were significantly associated with increased immediate postoperative opioid demand (P < 0.05). More invasive surgery, anxiety, revision surgery, and greater preoperative opioid use were significantly associated with a decreased incidence of opioid independence at 12 months postoperatively (P < 0.01). Greater preoperative opioid use prior to undergoing spine surgery predicts increased immediate postoperative opioid demand and decreased incidence of postoperative opioid independence. Psychiatric diagnoses in those using preoperative opioids were predictors of continued opioid use at 12 months. Patients may benefit from preoperative counseling that emphasizes minimizing opioid use prior to undergoing spine surgery. 2.

Effects of tramadol or morphine in dogs undergoing castration on intra-operative electroencephalogram responses and post-operative pain

AIM: To compare the effects of pre-operatively administered tramadol with those of morphine on electroencephalographic responses to surgery and post-operative pain in dogs undergoing castration.METHODS: Dogs undergoing castration were treated with either pre-operative morphine (0.5 mg/kg S/C, n = 8) or tramadol (3 mg/kg S/C, n = 8). All dogs also received 0.05 mg/kg acepromazine and 0.04 mg/kg atropine S/C in addition to the test analgesic. Anaesthesia was induced with thiopentone administered I/V to effect and maintained with halothane in oxygen. Respiratory rate, heart rate, end-tidal halothane tension (EtHal) and end-tidal CO2 tension (EtCO2) were monitored throughout surgery. Electroencephalograms (EEG) were recorded continuously using a three electrode montage. Median frequency (F50), total power (Ptot) and 95% spectral edge frequency (F95) derived from EEG power spectra recorded before skin incision (baseline) were compared with those recorded during ligation of the spermatic cords of both testicles. Post-operatively, pain was assessed after 1, 3, 6 and 9 h using the short form of the Glasgow composite measure pain scale (CMPS-SF).RESULTS: Dogs premedicated with tramadol had higher mean F50 (12.2 (SD 0.2) Hz) and lower Ptot (130.39 (SD 12.1) µv2) compared with those premedicated with morphine (11.5 (SD 0.2) Hz and 161.8 (SD 15.1) µv2, respectively; p<0.05) during ligation of testicle 1. There were no differences in EEG responses between the two treatment groups during ligation of testicle 2 (p>0.05). The F95 of the EEG did not differ between the two groups during the ligation of either testicle (p > 0.05). Post-operatively, no significant differences in the CMPS-SF score were found between animals premedicated with tramadol and morphine at any time during the post-operative period. No dog required rescue analgesia.CONCLUSION AND CLINICAL RELEVANCE: Tramadol and morphine administered pre-operatively provided a similar degree of post-operative analgesia in male dogs at the doses tested.

Effects of tramadol, morphine or their combination in dogs undergoing ovariohysterectomy on peri-operative electroencephalographic responses and post-operative pain

AIM: To compare the peri-operative electroencephalogram (EEG) responses and post-operative analgesic efficacy of pre-operative morphine or tramadol with a combination of low-dose pre-operative morphine and post-operative tramadol, in dogs undergoing ovariohysterectomy. METHODS: Dogs undergoing routine ovariohysterectomy were treated with either pre-operative morphine (0.5 mg/kg S/C, n=8), or tramadol (3 mg/kg S/C, n=8), or pre-operative low-dose morphine (0.1 mg/kg S/C) and post-operative tramadol (3 mg/kg I/V, n=8). All dogs received routine pre-anaesthetic medication, and anaesthesia was induced with I/V thiopentone to effect and maintained with halothane in oxygen. Respiratory rate, heart rate, end-tidal halothane tension (EtHal) and end-tidal CO2 tension (EtCO2) were monitored throughout surgery. The EEG was recorded continuously in a three electrode montage. Median frequency (F50), total power (Ptot) and 95% spectral edge frequency (F95) of the EEG power spectra were compared during different 100-second periods of surgery: prior to and during skin incision, ligation of each ovarian pedicle, ligation of uterine body and skin closure. Post-operatively, pain was assessed using the short form of the Glasgow composite measure pain scale (CMPS-SF). RESULTS: There was no difference in F50 or Ptot of the EEG between baseline and noxious surgical events within each treatment group, or between the three groups (p>0.05). The mean F95 was higher during the first three periods of surgery for dogs administered tramadol and low-dose morphine than those that received 0.5 mg/kg morphine (p=0.001). Dogs that received low-dose morphine and tramadol had lower CMPS-SF pain scores after ovariohysterectomy than those that received either tramadol or morphine alone (p=0.001). There was no difference in pain scores between dogs in the latter two groups. CONCLUSION AND CLINICAL RELEVANCE: Tramadol and morphine administered pre-operatively provided an equal degree of post-operative analgesia in dogs after ovariohysterectomy. A combination of pre-operative low-dose morphine and post-operative tramadol produced better post-operative analgesia than either drug administered alone pre-operatively. Administration of analgesics pre- and post-operatively could result in improved post-operative well-being of ovariohysterectomised dogs.

Intraoperative Ketamine and Chronic Opioid Use: Less Pain, More Morphine?

Christchurch Hospital, Christchurch, New Zealand. richard.seigne@cdhb.govt.nzThe recent paper by Loftus et al. ,1“Intraoperative ketamine reduces perioperative opiate consumption in opiate-dependent patients with chronic back pain undergoing back surgery,” was of interest to me because I occasionally use the technique described. This group of patients is very complex and I congratulate the authors for undertaking this study.There are four points that warrant clarification. First, the primary outcome of the study was based on data derived from a review of medical records (i.e. , mean [SD] 48-h postoperative oral morphine equivalent consumption of 500 [300] mg). However, the placebo group consumed only 309 (341) mg of this substance. Can the authors comment on this large difference and its possible relevance?Second, the term “morphine equivalents” requires further explication. This terminology was confusing because it was applied to oral and intravenous formulations. Which formulation was used was not always immediately clear. For example, in their table 1,1were “median preoperative morphine equivalents” delivered orally or intravenously? The text implies that these equivalents are intravenous morphine. If this supposition is correct, then it appears to me that both groups of patients may be consuming more morphine equivalents at 6-week follow-up (data presented as mean [SD]) than they did preoperatively (data presented as median [interquartile range]). In fact, the placebo group appears to have much higher rates of morphine consumption at 6 weeks compared with their own preoperative consumption levels and the treatment group's consumption at 6-week follow-up. There is a possibility that the treatment group's 6-week follow-up consumption has also increased from the preoperative period, which is concerning. Can the authors clarify and comment on these points?Third, the treatment group had more spinal levels operated on than did the control group. In fact, this difference reached statistical significance. However, this feature of the study was not addressed by the authors. Do the authors believe this difference was clinically significant?Finally, with regard to these observations, specifically with respect to possible increases in morphine consumption among both groups at 6-week follow-up and the chronic nature of back pain, I believe that a more extended follow-up period is warranted. Do the authors plan to do this?Christchurch Hospital, Christchurch, New Zealand. richard.seigne@cdhb.govt.nz

A two-year prospective study comparing lidocaine 2% jelly versus peribulbar anaesthesia for 25G and 23G sutureless vitrectomy

To evaluate the efficacy of topical lidocaine 2% gel with or without peroral preoperative sedation as an alternative anaesthetic method in sutureless vitreoretinal surgery. A prospective study was designed to assess the intraoperative and postoperative pain, using a visual analogue scale (VAS) in three groups of patients, comprised of 23 patients each. The first group included cases that were operated with 25-gauge (25G) instruments under topical anaesthesia with lidocaine jelly, the second group with 23-gauge (23G) under the same topical anaesthesia and finally the third group (control group) with sutureless (23- or 25-gauge) vitrectomy under peribulbar anaesthesia. Mann Whitney U test was used to compare the results. The subjective surgeon's opinion about the difficulty of each procedure was recorded on a 1-5 scale and the results were evaluated with a chi-square test. No statistically significant difference in the level of pain was detected between the three groups. Topical anaesthesia vitrectomy procedures were performed more easily (p = 0.0002) with 23-gauge than with 25-gauge instruments. The painful steps of the surgery that were capable of causing moderate to severe pain were endolaser, scleral indentation and peribulbar injection. The goal of the operations was accomplished in all cases. Lidocaine 2% jelly with or without peroral preoperative morphine and dixyrazine offers adequate analgesia to perform sutureless vitrectomy. Lack of akinesia does not prevent a successful surgical result.

Effect of Preoperative Epidural Morphine Administration on Desflurane Requirements During Gynecologic Surgery

Effect of Preoperative Epidural Morphine Administration on Desflurane Requirements During Gynecologic Surgery

A preliminary investigation comparing pre–operative morphine and buprenorphine for postoperative analgesia and sedation in cats

ObjectiveTo compare the postoperative analgesic and sedative properties of buprenorphine and morphine in cats. Study designProspective, randomized, blinded study. AnimalsThirty–two domestic cats undergoing surgery. MethodsCats received pre–anaesthetic medication with acepromazine (0.05 mg kg−1) given intramuscularly and were randomly allocated to group M and given morphine (0.1 mg kg−1) intramuscularly (IM) or to group B and given buprenorphine (0.01 mg kg−1) IM. Anaesthesia was induced with propofol and maintained with halothane in oxygen and nitrous oxide. Pain and sedation scores using visual analogue scales, and heart and respiratory rates, were measured immediately before, and 30, 60, 120, 180, 300 and 420 minutes after anaesthesia. ResultsPain scores were significantly lower at 60, 120 and 180 minutes after anaesthesia in group B. Group B also had higher heart rates at 30 minutes. There were no other statistically significant differences between the groups. Clinical relevanceBuprenorphine (0.01 mg kg−1) appeared to provide better postoperative analgesia than morphine (0.1 mg kg−1) and may also have a longer duration of action.