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INTRODUCTION: The post-anaesthetic phase is most often uncomplicated, but patients may experience inadequate emergence (IE) characterized by unrest, restlessness, aggressiveness or in contrast sedation or lack of initiative. This may increase length of stay (LOS) and post-operative complications. The aim of this study was to investigate frequency, risk factors and consequences of IE. METHODS: We conducted an observational cohort study including 1000 orthopaedic and abdominal surgical patients, screened with the Nursing Delirium Screening Scale (Nu-DESC) before induction of anaesthesia, at arrival at the post-operative care unit, and just before discharge from PACU. IE was defined as a Nu-DESC score ≥2 after surgery. Predictors included surgical procedure, type and duration of anaesthesia, age, ASA-score, sex and post-operative pain. Data were analysed during adjusted logistic regression and Wilcoxon rank sum test, the primary outcome being LOS. RESULTS: IE occurred in 103 of 1000 patients (10.3%, 95% CI 8.6-12.3%). LOS was median 2 vs 1 day in patients with and without IE, mean difference was 1.3 (SD 6.2) days (P = 0.036). Thirty-day mortality was 2.9 vs 1.0% (P = 0.92) and admission to ICU 1.0 vs 0.9% (P = 0.66) in patients with and without IE. Significant associations to IE were found for inhalational anaesthetics (OR 2.65; 95% CI: 1.57-4.46), duration of anaesthesia ≥2 hours (OR 1.98; 95% CI: 1.14-3.44) and ASA-score ≥3 (OR 2.74; 95% CI: 1.64-4.57). CONCLUSION: One of 10 patients had IE as defined by the Nu-DESC score, which was significantly associated with increased LOS. Longer duration of anaesthesia, inhalational anaesthesia and ASA ≥3 were significantly associated to this.

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It is suggested that genetic variations explain a significant portion of the variability in pain perception; therefore, increased understanding of pain-related genetic influences may identify new targets for therapies and treatments. The relative contribution of the different genes to the variance in clinical and experimental pain responses remains unknown. It is suggested that the genetic contributions to pain perception vary across pain modalities. For example, it has been suggested that more than 60% of the variance in cold pressor responses can be explained by genetic factors; in comparison, only 26% of the variance in heat pain responses is explained by these variations. Thus, the selection of pain model might markedly influence the magnitude of the association between the pain phenotype and genetic variability. Thermal pain sensation is complex with multiple molecular and cellular mechanisms operating alone and in combination within the peripheral and central nervous system. It is thus highly probable that the thermal pain experience is affected by genetic variants in one or more of the pathways involved in the thermal pain signaling. This review aims to present and discuss some of the genetic variations that have previously been associated with different experimental thermal pain models.

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INTRODUCTION: Development of secondary hyperalgesia following a cutaneous injury is a centrally mediated, robust phenomenon. The pathophysiological role of endogenous opioid signalling to the development of hyperalgesia is unclear. Recent animal studies, carried out after the resolution of inflammatory pain, have demonstrated reinstatement of tactile hypersensitivity following administration of µ-opioid-receptor-antagonists. In the present study in humans, we analyzed the effect of naloxone when given after the resolution of secondary hyperalgesia following a first-degree burn injury. METHODS: Twenty-two healthy volunteers were included in this placebo-controlled, randomized, double-blind, cross-over study. Following baseline assessment of thermal and mechanical thresholds, a first-degree burn injury (BI; 47°C, 7 minutes, thermode area 12.5 cm(2)) was induced on the lower leg. Secondary hyperalgesia areas around the BI-area, and separately produced by brief thermal sensitization on the contralateral thigh (BTS; 45°C, 3 minutes, area 12.5 cm(2)), were assessed using a polyamide monofilament at pre-BI and 1, 2, and 3 hours post-BI. At 72 hrs, BI and BTS secondary hyperalgesia areas were assessed prior to start of a 30 minutes intravenous infusion of naloxone (total dose 21 microg/kg) or placebo. Fifteen minutes after start of the infusion, BI and BTS secondary hyperalgesia areas were reassessed, along with mechanical and thermal thresholds. RESULTS: Secondary hyperalgesia areas were demonstrable in all volunteers 1-3 hrs post-BI, but were not demonstrable at 72 hrs post-burn in 73-86% of the subjects. Neither magnitude of secondary hyperalgesia areas nor the mechanical and thermal thresholds were associated with naloxone-treated compared to placebo-treated subjects. CONCLUSION: Naloxone (21 microg/kg) did not reinstate secondary hyperalgesia when administered 72 hours after a first-degree burn injury and did not increase BTS-generated hyperalgesia. The negative results may be due to the low dose of naloxone or insufficient tissue injury to generate latent sensitization.

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CONTEXT: The analgesic effect of transversus abdominis plane (TAP) block after inguinal hernia repair is unclear. OBJECTIVE: The aim of this randomised and double-blind study was to evaluate the analgesic effect of a TAP block in patients scheduled for primary inguinal hernia repair. The TAP block was evaluated versus placebo and versus an active comparator (ilioinguinal block and wound infiltration). DESIGN: Randomised controlled trial. SETTING: Single centre trial. Study period from June 2010 to November 2011. PATIENTS: Adults (18 to 75 years) with American Society of Anesthesiologists' status 1-3 scheduled for primary inguinal hernia repair as day case surgery were included in the study. INTERVENTIONS: Ninety patients were allocated to one of three groups: group TAP, group infiltration (ilioinguinal nerve block and wound infiltration) and group placebo. MAIN OUTCOME MEASURES: The primary outcome measure was pain scores while coughing between group TAP and group placebo calculated as area under the curve for the first 24  h (AUC24 h). Secondary outcomes were pain scores while coughing and at rest, opioid consumption and side effects in groups TAP, infiltration and placebo. RESULTS: Visual analogue pain scores while coughing and at rest demonstrated no difference between groups. Pain scores in groups infiltration, TAP and placebo were 19 versus 22 versus 15  mm at rest (P = 1.00) and 37 versus 41 versus 37  mm while coughing (P = 1.00). Pain scores at 6 h (AUC6 h) were significantly lower in group infiltration than in group TAP (10 versus 25 mm at rest, P < 0.001; 17 versus 40  mm while coughing, P < 0.001), and than in group placebo (10 versus 20  mm at rest, P = 0.003; 17 versus 38  mm while coughing, P < 0.001). Median morphine consumption was lower in group infiltration than in group placebo (0 versus 5 mg, P < 0.003). No differences among groups were demonstrated for ketobemidone consumption or side effects. CONCLUSION: Ultrasound-guided TAP block did not reduce postoperative pain after inguinal hernia repair. TRIAL REGISTRATION: Clinicaltrials.gov identifier: NCT01052285. EudraCT number 2010-018403-29.

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BACKGROUND: Laparoscopic cholecystectomy is associated with postoperative pain of moderate intensity in the early postoperative period. Recent randomized trials have demonstrated the efficacy of transversus abdominis plane (TAP) block in providing postoperative analgesia after abdominal surgery. We hypothesized that a TAP block may reduce pain while coughing and at rest for the first 24 postoperative hours, opioid consumption, and opioid side effects in patients undergoing laparoscopic cholecystectomy in day-case surgery. METHODS: In this randomized, double-blind study, 80 patients undergoing laparoscopic cholecystectomy in our day-case surgery unit were allocated to receive either bilateral ultrasound-guided posterior TAP blocks (20 mL 0.5% ropivacaine) or placebo blocks. Postoperative pain treatment consisted of oral acetaminophen 1000 mg × 4, oral ibuprofen 400 mg × 3, IV morphine (0-2 hours postoperatively), and oral ketobemidone (2-24 hours postoperatively). The primary outcome was postoperative pain scores while coughing calculated as area under the curve for the first 24 postoperative hours (AUC/24 h). Secondary outcomes were pain scores at rest (AUC/24 h), opioid consumption, and side effects. Patients were assessed 0, 2, 4, 6, 8, and 24 hours postoperatively. Group-wise comparisons of visual analog scale (VAS) pain (AUC/24 h) were performed with the 2-sample t test. Morphine and ketobemidone consumption were compared with the Mann-Whitney test for unpaired data. Categorical data were analyzed using the χ(2) test. RESULTS: The primary outcome variable, VAS pain scores while coughing (AUC/24 h), was significantly reduced in the TAP versus the placebo group (P = 0.04); group TAP: 26 mm (SD 13) (weighted average level) versus group placebo: 34 (18) (95% confidence interval): 0.5-15 mm). VAS pain scores at rest (AUC/24 h) showed no significant difference between groups. Median morphine consumption (0-2 hours postoperatively) was 7.5 mg (interquartile range: 5-10 mg) in the placebo group compared with 5 mg (interquartile range: 0-5 mg) in the TAP group (P < 0.001). The odds ratio of a random patient in group TAP having less morphine consumption than a random patient in group placebo was P (group TAP < group placebo) = 0.26 (confidence interval: 0.15, 0.37) where 0.5 represents no difference between groups. There were no between-group differences in total ketobemidone consumption, levels of nausea and sedation, number of patients vomiting, or consumption of ondansetron. CONCLUSIONS: TAP block after laparoscopic cholecystectomy may have some beneficial effect in reducing pain while coughing and on opioid requirements, but this effect is probably rather small.

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BACKGROUND AND OBJECTIVE: It has been hypothesized that combinations of analgesics with different mechanisms of action may reduce or even prevent postoperative pain. We, therefore, investigated the analgesic effect of gabapentin, dexamethasone and low-dose ketamine in combination with paracetamol and ketorolac as compared with paracetamol and ketorolac alone after hip arthroplasty. METHODS: In this double-blind study, 42 patients were randomly assigned to either a combination group [gabapentin 1200 mg+dexamethasone 8 mg+ketamine (0.15 mg kg(-1))+paracetamol 1 g+ketorolac 15 mg] or a control group (placebo+paracetamol 1 g+ketorolac 15 mg). The medication was given preoperatively except for ketorolac, which was given at the end of surgery. Postoperative pain treatment was paracetamol 1 gx3; ketorolac 15 mgx3; and patient-controlled intravenous morphine. Morphine consumption, pain intensity at rest and during mobilization, nausea and vomiting, sedation, dizziness, hallucination and consumption of ondansetron were recorded 2, 4 and 24 h after operation. A P value of less than 0.05 was considered statistically significant. RESULTS: Morphine consumption was not significantly different between groups (P=0.085). Overall pain scores were improved in the combination group as compared with the control group both at rest (P=0.042) and during mobilization (P=0.027). In the combination group, individual pain score above 30 mm on a 100 mm visual analogue scale was almost eliminated. The incidence of side effects did not differ between the groups. CONCLUSION: Preoperative gabapentin, dexamethasone and ketamine combined with paracetamol and ketorolac reduced overall pain scores in patients after hip arthroplasty as compared with paracetamol and ketorolac alone. Morphine consumption was not reduced.

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BACKGROUND: A considerable number of patients require opioids during recovery after laparoscopic sterilization. This implies nausea, dizziness and sedation and increases the number of unplanned admissions. Gabapentin has shown excellent postoperative analgesic effect in a number of recent studies with few side effects. This study was designed to test whether gabapentin given preoperatively can reduce the number of patients needing morphine in the recovery period. METHODS: 80 females scheduled for laparoscopic sterilization using Filshie clips were randomized to two treatment groups (Gaba group and control group). All patients received lornoxicam 8 mg p.o. 30 min. before the procedure. Patients in the Gaba group received gabapentin 1200 mg p.o. and patients in the control group received placebo capsules prior to the procedure. All patients were anesthetized according to a protocol, using remifentanil and propofol. Postoperative analgesia was obtained with patient controlled infusion of morphine. Pain, nausea, dizziness and sedation were scored at 2 and 4 hours after end of anesthesia. The expenditure of morphine was the primary measure for the effect of analgesia and the number of patients demanding morphine was the primary endpoint. RESULTS: Three patients were excluded because of procedural errors and one because of conversion to open surgery. 38 patients completed the study in each group.32 (84%) patients in the gabapentin group and 37 (97%) patients in the control group did require morphine in the recovery period. (p = 0,049). There was no significant difference between mean morphine consumption, pain scores and frequency of adverse effects (nausea, dizziness, sedation and vomiting) CONCLUSION: The postoperative analgesic effect of gabapentin given preoperatively was confirmed in this study. For this procedure, with pain predominantly in the immediate recovery period, and of less intensity than after major surgical procedures, the effect demonstrated is much less pronounced than in similar studies of major surgery. General use of gabapentin as analgesic for laparoscopic sterilization is not supported by this study. TRIAL REGISTRATION: Current Controlled Trials ISCRTN39209275.