Usefulness of the pain sensitivity questionnaire to discriminate the pain behaviour of chronic pain patients.

BACKGROUND: Chronic pain is no longer an effective warning system, but a syndrome with co-morbidities and many causes, needing a careful evaluation. Questions remain about the pain behaviour of chronic pain patients compared with patients with acute pain, or healthy subjects that we investigated. METHODS: We compared three populations: healthy (HS, n=280), with acute pain (AP=110 patients), and chronic pain (CP=280 patients) by assessing their pain behaviour with the pain sensitivity questionnaire (PSQ-total and PSQ-minor). The influence of central sensitisation syndrome (CSS) on chronic pain behaviour, including catastrophising, was further investigated by using the central sensitisation inventory. RESULTS: Compared with the AP patients and HS, the CP patients exhibited significantly higher catastrophising scores; higher PSQ-minor scores [29.0 (21.0-39.0), than for AP 24.0 (14.0-32.5), and for healthy subjects 25.0 (17.0-34.0); and PSQ-total scores of for CP, 63.5 for AP, and 64.0 for HS. No significant difference was observed between the HS and AP populations. Significant differences were observed between the CP patients with and without CSS. The median PSQ-minor for patients with CSS was 33.0 and without CSS was 25.0 (P<0.05); the median PSQ-total for patients with CSS was 82.0 and without CSS was 65 (P<0.05). The CP patients without CSS did not show any significant difference compared with the AP and HS groups, except for catastrophising. CONCLUSIONS: This study highlights the influence of CSS in the results of PSQ and catastrophising by chronic pain patients in comparison with healthy controls and acute pain patients. CLINICAL TRIAL REGISTRATION: P2014/134.

Impact of an anticaries mouthrinse on in vitro remineralization and microbial control.

Objective. The objective of this research was to evaluate the caries control potential of a new fluoride mouthrinse that also contained antimicrobial agents and a biofilm disrupting agent using different in vitro models. Methods. Four in vitro studies were conducted to assess the performance of this three pronged approach to caries control: (1) traditional enamel fluoride uptake, (2) surface microhardness study using pH cycling model and subsequent fluoride uptake, (3) a salivary biofilm flow-through study to determine the anti-microbial activity, and (4) a single species biofilm model measuring effect on biofilm matrix disruption. Results. The data showed that a LISTERINE rinse with fluoride, essential oils and xylitol was superior in promoting enamel fluoride uptake and in enhancing antimicrobial activity over traditional commercially available fluoridated products. An increase of the surface microhardness was observed when the LISTERINE rinse was used in combination with fluoridated toothpaste versus the fluoridated toothpaste alone. Finally, it was demonstrated that xylitol solutions disrupted and reduced the biovolume of biofilm matrix of mature Streptococcus mutans. Conclusion. These in vitro studies demonstrated that a fluoride mouthrinse with antimicrobial agent and biofilm matrix disrupting agent provided multifaceted and enhanced anti-caries efficacy by promoting remineralization, reducing acidogenic bacteria and disrupting biofilm matrix.

Efficacy of adding clonidine to intrathecal morphine in acute postoperative pain: meta-analysis.

BACKGROUND: Clonidine may be used along with intrathecal morphine for single-dose postoperative analgesia in adults. The efficacy of this is not clear. METHODS: A meta-analysis was performed for two endpoints of efficacy: the time to first postoperative analgesia request and the amount of systemic morphine used during the first 24 h after operation. A Bayesian inference supporting direct statements about the probability of the magnitude of an effect was also used. The frequency of the five adverse events (postoperative nausea or vomiting, sedation, respiratory depression, pruritus, and hypotension) was analysed. RESULTS: Clonidine increased the duration of analgesia by 1.63 h [95% confidence interval (CI): 0.93-2.33]. There is a 90% probability that clonidine increases the duration of postoperative analgesia by more than 75 min compared with morphine alone. Clonidine reduced the amount of postoperative morphine by a mean of 4.45 mg (95% CI: 1.40-7.49 mg). There is a probability of 90% to obtain a decrease >2.3 mg but only 35% to obtain a decrease >5 mg. The incidence of hypotension was the only adverse event increased by clonidine (odds ratio 1.78; 95% CI: 1.02-3.12). CONCLUSIONS: The addition of clonidine to intrathecal morphine extends the time to first analgesia and decreases the amount of morphine used. However, as the effects are small, and the results heavily influenced by a study in which intrathecal fentanyl was also given, this must be balanced with the increased frequency of hypotension.

Bayesian enhanced meta-analysis of post-operative analgesic efficacy of additives for caudal analgesia in children.

BACKGROUND: The authors calculated the effect size for post-operative analgesia of three additives, clonidine, neostigmine, and tramadol to bupivacaine, ropivacaine, or levobupivacaine used for single-dose caudal extradural blockade in children. METHODS: A meta-analysis was performed for three end points of efficacy: the increase of time until administration of analgesic drugs, the proportion of patients requiring analgesic drugs during the initial 24 post-operative hours, and the amounts of post-operative analgesic drugs. A Bayesian inference supporting direct statements about the probability of the magnitude of an effect was used to compare the effects size. RESULTS: Neostigmine increased the duration of analgesia by 9.96 h (95% confidence interval: 7.75 to 12.16), as compared with 3.68 h (2.65 to 4.7) with clonidine and 4.45 (2.84 to 6.07) with tramadol. There is a 95% probability that neostigmine increases the duration of post-operative analgesia by more than 8 h, clonidine by more than 2.8 h, and tramadol by more than 3.25 h, as compared with local anesthetics alone. The odds ratios for the proportion of patients requiring analgesic drugs were 0.22 [0.13 to 0.37] for clonidine and 0.28 [0.10 to 0.75] for neostigmine. With tramadol, there was no statistically significant difference. All three additives reduced the amounts of post-operative analgesic drugs. Neostigmine and tramadol increase the probability for post-operative nausea or vomiting (PONV). CONCLUSIONS: Neostigmine provides the longest post-operative analgesia. With clonidine, the duration of analgesia is shorter and sedation is increased, but the probability for PONV could be decreased.

Low-dose intravenous ketamine and clonidine for poor postoperative opioid responsiveness: a double blind randomized study.

In the immediate postoperative period, some patients present with pain that responds poorly to intravenous opioids. In a double-blind randomized study, we tested the hypothesis that administering small doses of intravenous ketamine (0.125 mg/kg) combined with clonidine (0.5 microg/kg) would enhance the speed of onset and the quality of an opioid analgesic regimen in patients who initially responded poorly to opioids. We enrolled 68 patients in the study, all physical status I to III according to the American Society of Anesthesiologists classification. If the patient's numerical rating scale (NRS) score remained > or = 5 after an initial intravenous injection of 10 mg piritramide (2-mg boluses every 5 minutes) in the post-anesthesia care unit, patients were randomized to either intravenous placebo (sodium chloride 0.9%) or active substances (ketamine 0.125 mg/kg plus clonidine 0.5 microg/kg). Fifteen minutes after administration of either placebo or active agents, patients with severe pain (NRS > 4) again received intravenous opioids until NRS < 4. The primary endpoint of the study was to reduce by 20 minutes the time necessary to achieve an NRS < 4. There was no statistically significant difference between the two groups regarding the time required for patients to achieve an NRS < 4. It was concluded that in the immediate postoperative period, the acute administration of small combined doses of intravenous ketamine (0.125 mg/kg) and clonidine (0.5 mirog/kg) does not reduce the onset of an opioid-based analgesia in patients with an initial poor response to intravenous opioids.

Efficacy and safety of perioperative pregabalin for post-operative pain: a meta-analysis of randomized-controlled trials.

We calculated in a meta-analysis the effect size for the reduction of post-operative pain and post-operative analgesic drugs, which can be obtained by the perioperative administration of pregabalin. Three end-points of efficacy were analysed: early (6 h-7 days) post-operative pain at rest (17 studies) and during movement (seven studies), and the amount of analgesic drugs in the studies that obtained identical results for pain at rest (12 studies). Reported adverse effects were also analysed. The daily dose of pregabalin ranged from 50 to 750 mg/day. The duration of treatment in patients assessed for pain ranged from a single administration to 2 weeks. Pregabalin administration reduced the amount of post-operative analgesic drugs (30.8% of non-overlapping values - odds ratio=0.43). There was no effect with 150, and 300 or 600 mg/day provided identical results. Pregabalin increased the risk of dizziness or light-headedness and of visual disturbances, and decreased the occurrence of post-operative nausea and vomiting (PONV) in patients who did not receive anti-PONV prophylaxis. The administration of pregabalin during a short perioperative period provides additional analgesia in the short term, but at the cost of additional adverse effects. The lowest effective dose was 225-300 mg/day.

Remifentanil patient-controlled analgesia effect-site target-controlled infusion compared with morphine patient-controlled analgesia for treatment of acute pain after uterine artery embolization.

BACKGROUND: Post-procedural pain control after uterine artery embolization (UAE) of urethral leiomyomata remains a major problem. METHODS: This double-blind, randomized study tested the possibility to obtain a quicker onset of analgesia by using effect-compartment controlled remifentanil patient-controlled analgesia (remifentanil TCI-PCA) than by using i.v. morphine PCA. Both systems were connected to an i.v. catheter. Active drug or matching placebo administration was activated by a single push-button. Pain was assessed using a numerical rating scale (NRS) from 0 to 10. RESULTS: NRS values were lower in the remifentanil group (with a possible difference from two to seven points on the scale) during the initial 4 h post-embolization. After the fourth hour, the NRS values were identical between the groups. No major respiratory or haemodynamic side-effect was observed. CONCLUSIONS: Remifentanil PCA-TCI with a slow and progressive adapted algorithm without any associated premedication or co-medication is feasible in young healthy women undergoing UAE.

Ketamine has no effect on bispectral index during stable propofol-remifentanil anaesthesia.

BACKGROUND: Ketamine 0.15-1 mg kg(-1) decreases postoperative morphine consumption, but 0.5 mg kg(-1) is associated with an increase in the bispectral index (BIS) values that can lead to an overdose of hypnotic agents. The purpose of our investigation was to study the effect of ketamine 0.2 mg kg(-1) administered over a 5 min period on the BIS during stable target-controlled infusion (TCI) propofol-remifentanil general anaesthesia. METHODS: Thirty ASA I or II patients undergoing abdominal laparoscopic surgery were included in this double-blind, randomized study. Anaesthesia was induced and maintained with a TCI of propofol and remifentanil. After 5 min of steady-state anaesthesia (BIS at 40) without surgical stimulation, patients received either an infusion of ketamine 0.2 mg kg(-1) or normal saline. The test drug was infused over 5 min. Standard parameters and BIS values were recorded every minute until 15 min post-infusion. RESULTS: The baseline mean (sd) value for the BIS was 37 (6.5) for the ketamine group and 39 (8.2) for the placebo group. The highest mean BIS value during the recording period was 41.5 (8.7) for the ketamine group and 40.1 (8.9) for the placebo group. BIS values were not statistically different between the groups (P=0.62); there was no significant change over time (P=0.65) with no group-time interaction (P=0.55). CONCLUSIONS: Under stable propofol and remifentanil TCI anaesthesia, a slow bolus infusion of ketamine 0.2 mg kg(-1) administered over a 5 min period did not increase the BIS value over the next 15 min.

Effect site concentrations of remifentanil and pupil response to noxious stimulation.

BACKGROUND: Opioid drugs block reflex pupillary dilatation in response to noxious stimulation. The relationship between the target effect site concentration (Ce(T)) of remifentanil and the pupil diameter and reactivity in response to a standard noxious stimulus were evaluated. METHODS: Anaesthesia was induced with propofol TCI to obtain loss of consciousness (LOC) in 12 ASA I/II patients. Thereafter, remifentanil Ce(T) was titrated by increments of 1 up to 5 ng ml(-1). In the awake state, at LOC and at each plateau level of remifentanil Ce(T), arterial pressure, heart rate, and BIS (A2000) were recorded. Pupil size and dilatation after a 100 Hz tetanic stimulation (T100) were measured at LOC and at each plateau level of remifentanil Ce(T). RESULTS: LOC was observed at a mean propofol Ce(T) of 3.53 (SD 0.43) microg ml(-1). Arterial pressure and heart rate decreased progressively from LOC to 5 ng ml(-1) remifentanil Ce(T) without any statistical difference between each incremental dose of remifentanil. Mean BIS values decreased from 96 (2) in the awake state, to 46 (12) at LOC (P<0.05) and then remained unchanged at all remifentanil Ce(T). Pupil dilatation in response to 100 Hz tetanic stimulation decreased progressively from 1.55 (0.72) to 0.01 (0.03) mm and was more sensitive than pupil diameter measured before and after 100 Hz tetanus. An inverse correlation between pupil dilatation in response to 100 Hz tetanus and an increase in remifentanil Ce(T) from 0 to 5 ng ml(-1) was found (R(2)=0.68). CONCLUSIONS: During propofol TCI in healthy patients, the decrease in pupil response to a painful stimulus is a better measurement of the progressive increase of remifentanil Ce(T) up to 5 ng ml(-1) than haemodynamic or BIS measurements.

[The anesthesiology-recovery department]. / Le Service d'Anesthésiologie Réanimation.

The Department of Anesthesiology and Reanimation is organised in units with clinical activities, which include the pre-operative care of patients, anesthesiological care and immediate post-operative supervision. Two post-operative treatment rooms also form part of the department. The main fields of research of the various units result from collaborations with other departments of Hôpital Erasme, in particular with regard to the development of advanced techniques or fit within the confines of the speciality.

Effects of propofol, etomidate, and pentobarbital on critical oxygen delivery.

OBJECTIVE: To test the hypothesis that propofol, etomidate, and pentobarbital increase critical oxygen delivery in a dose-dependent manner during progressive hemorrhage. DESIGN: Prospective, randomized laboratory investigation. SETTING: University laboratory. SUBJECTS: A total of 40 anesthetized, paralyzed, and mechanically ventilated dogs weighing 29.2+/-4.6 kg. INTERVENTIONS: Dogs were randomly assigned to be anesthetized with propofol (n = 13), etomidate (n = 13), or pentobarbital (n = 14) at either low or high dosages. At 30 mins after splenectomy, the dogs underwent progressive hemorrhage by successive withdrawals of 3-5 mL/kg arterial blood. MEASUREMENTS AND MAIN RESULTS: At each step of hemorrhage, oxygen consumption and oxygen delivery were determined. Oxygen consumption was obtained from expired gas analysis, and oxygen delivery was determined from thermodilution cardiac output and calculated arterial oxygen content. In each animal, critical oxygen delivery and critical oxygen consumption were obtained from a plot of oxygen consumption vs. oxygen delivery as the point of intersection of the two best-fit regression lines determined by a least sum of squares method. Critical oxygen extraction was obtained by dividing critical oxygen consumption by critical oxygen delivery. In the three groups, animals receiving the higher anesthetic infusion had a significantly higher critical oxygen delivery (propofol: 10.5+/-0.8 vs. 13.9+/-2.5 mL/min/m2, p < .05; etomidate: 10.1+/-0.7 vs. 13.4+/-3.0 mL/min/m2, p < .05; pentobarbital: 7.8+/-1.0 vs. 12.3+/-2.5 mL/min/m2, p < .01) attributable to a lower critical oxygen extraction ratio (propofol: 41.1+/-6.4% vs. 54.2+/-2.5%, p < .01; etomidate: 42.7+/-10.2% vs. 60.6+/-7.1%, p < .01; pentobarbital: 42.2+/-7.2% vs. 64.3+/-8.8%, p < .01). CONCLUSIONS: This study indicates that propofol, etomidate, and pentobarbital increased critical oxygen delivery in a dose-dependent manner. This effect was mainly related to a decrease in tissue oxygen extraction capabilities.

Airway pressure changes during one-lung ventilation.

This investigation analyzed the changes in inspiratory airway pressures during transition from two-lung to one-lung ventilation in patients tracheally intubated with a double-lumen endotracheal tube (DLT) using a classical method of intubation without fiberoptic bronchoscopy. All patients were anesthetized in a standardized fashion. Ventilation was accomplished with the Siemens 900 constant-flow mechanical ventilator (Solna, Sweden). Peak (Ppeak) and plateau (Pplateau) inspiratory airway pressures were recorded with an on-line respiratory monitor before and after clamping the tracheal limb of the DLT. The position of the DLTs was evaluated by fiberoptic bronchoscopy with the patient in supine position. Of the 51 intubations, the DLT was malpositioned in 15 cases (29.5%). Ppeak and Pplateau increased significantly when switched from two-lung ventilation to one-lung ventilation in both correctly and incorrectly positioned DLTs. When the DLT was in a correct position, Ppeak increased by a mean of 55.1% and Pplateau increased by a mean of 41.9%. When the DLT was malpositioned, this increase was significantly larger (74.9% and 68.8%, respectively). Three tests commonly used as markers of malpositioned DLTs were evaluated based on the data of this study, and it was established that, although the pressure differences related to position are statistically significant, as a single value, they cannot be used for clinical decision making.

Intravenous nicardipine in the treatment of postoperative arterial hypertension.

BACKGROUND: Calcium entry blockers are commonly used in the management of postoperative hypertension. The hemodynamic and blood gas effects of nicardipine, a dihydropyridine derivative available intravenously, were studied in patients after abdominal aortic surgery. METHODS: Sixteen patients (66 +/- 8 years) who developed arterial hypertension (mean arterial pressure, > 90 mmHg) after abdominal aortic aneurysm reconstruction were studied. Fourteen patients had already been treated with a sodium nitroprusside infusion, the doses of which were maintained constant (mean dose: 1.42 +/- 1.04 micrograms/kg/min). Hemodynamic and blood gas data were collected at baseline, 15 minutes, and 45 minutes after a slow bolus administration of 3 to 5 mg of nicardipine. RESULTS: After the nicardipine administration, mean arterial pressure decreased from 101 +/- 11 to 83 +/- 11 mmHg (p < 0.001), and the cardiac index acutely increased from 3.96 +/- 0.74 to 4.57 +/- 0.83 L/min/m2 (p < 0.05). Systemic vascular resistance significantly decreased. There were no significant changes in heart rate, stroke volume, cardiac filling pressures, pulmonary artery pressures, pulmonary vascular resistance, left ventricular stroke work, or right ventricular stroke work. One patient developed acute pulmonary edema, associated with a dramatic increase in cardiac filling pressures, and electrocardiographic signs of myocardial ischemia. Nicardipine administration was also associated with an acute reduction in Pao2 from 85.0 +/- 12.1 mmHg to 70.3 +/- 9.2 mmHg (p < 0.001), associated with an increase in venous admixture from 21.7% +/- 3.2% to 28.0% +/- 5.2% (p < 0.01). Oxygen delivery increased moderately and oxygen extraction decreased, but oxygen consumption was unchanged. CONCLUSION: This study confirms the excellent efficacy of nicardipine in the management of postoperative hypertension, but underlines the risk of poor cardiac tolerance in patients after major surgery. Although oxygen delivery to the cells is usually well preserved, nicardipine can also significantly after blood oxygenation by increasing ventilation/perfusion mismatch.

Intrinsic positive end-expiratory pressure during one-lung ventilation for thoracic surgery. The influence of preoperative pulmonary function.

OBJECTIVE: To detect and to quantify intrinsic positive end-expiratory pressure (PEEPi) during thoracic surgery in the dependent lung of patients intubated with a double-lumen endotracheal tube (DLT) in the lateral position. METHODS: Twenty consecutive patients undergoing elective pulmonary resection were anesthetized, paralyzed, and intubated with a DLT. Their lungs were ventilated (Siemens Servo 900 C ventilator; Siemens Elevna; Solna, Sweden) with constant inspiratory flow. Fraction of inspired oxygen, tidal volume (10 mL/kg), frequency (10/min), and inspiratory time/total time (0.33) were kept constant during the study. PEEPi and ventilatory data were measured in the dependent lung in the supine then in the lateral position with a closed hemithorax. The obtained data were analyzed according to the presence (group PH) or absence (group N) of pulmonary hyperinflation determined from the preoperative pulmonary function data as higher than 120% of predicted value of functional residual capacity (FRC) and residual volume (RV). DATA ANALYSIS: In the dependent lung of patients in group PH (n = 11), PEEPi was present in the supine (n = 8) and in the lateral (n = 11) positions in the range of 1 to 10 cm H2O. In group N (n = 9), PEEPi was detected in one patient and only in the supine position. In the whole group of 20 patients, the preoperative value of FRC (% predicted) and RV (% predicted) was statistically significantly correlated to the presence of PEEPi, whereas the preoperative FEV1 (% predicted) was poorly related to PEEPi in both positions. There was no significant correlation between the value of PaCO2 and PEEPi during one-lung ventilation (OLV) but patients in group PH had a significantly higher PaCO2 during OLV than group N (p = 0.012). CONCLUSIONS: In patients with chronic obstructive lung disease and pulmonary hyperinflation, PEEPi occurs commonly during the period of OLV and only occasionally in patients with normal lungs. As the ventilatory pattern, the size of DLT, and the side of surgery were similar in the two groups of patients, we conclude that the occurrence of PEEPi in our patients was influenced mainly by the preexisting pulmonary hyperinflation and airflow obstruction.