T. Koch

Does Femoral Nerve Catheter Placement with Stimulating Catheters Improve Effective Placement? A Randomized, Controlled, and Observer-Blinded Trial

Continuous peripheral nerve blocks offer the benefit of extended postoperative analgesia and accelerated functional recovery after major knee surgery. Conventional nerve localization is performed over a stimulating needle followed by blind insertion of the peripheral catheter. Correct catheter placement is confirmed by testing for satisfactory analgesia. Stimulating catheters offer the advantage of verifying correct placement close to the nerve during catheter placement. The aim of this randomized trial was to determine whether accurate catheter positioning under continuous stimulation accelerates the onset of sensory and motor block, improves the quality of postoperative analgesia, and enhances functional recovery. We compared femoral nerve catheters inserted under continuous stimulation with catheters that were placed using the conventional technique of blind advancement in 81 patients undergoing major knee surgery. Time of catheter placement was similar in both groups with 4 min (3/7.3; median, 25th/75th percentile) in the conventional group and 5 min (4/8.8) in the stimulating catheter group. In both groups, 42% of the catheters could be correctly placed (motor response of the patella with a current ≤0.5 mA) at first attempt. In 22 patients (58%) of the stimulating catheter group, the catheter had to be redirected 1–20 times, including 2 that could not be correctly placed within 20 min. The onset time of sensory and motor block was almost similar in both groups. There were no differences in the postoperative IV opioid consumption, and visual analog scale pain scores at rest and movement, or maximal bending and stretching of the knee joint during the 5 days after surgery. We conclude that with continuous femoral nerve blocks, blind catheter advancement is as effective as the stimulating catheter technique with respect to onset time of sensory and motor block as well as for postoperative pain reduction and functional outcome.

Risk factors for prilocaine-induced methaemoglobinaemia following peripheral regional anaesthesia

Background: The local anaesthetic prilocaine has a low systemic toxicity mainly because of a high absorption in the lung and a large volume of distribution and thus is associated with a lower risk of neurological or cardiac side‐effects. However, the major disadvantage is the formation of methaemoglobin by its metabolite o‐toluidine. This prospective observational study was performed to identify factors that are associated with increased prilocaine‐induced methaemoglobinaemia. Patients and methods: One Hundred and sixty two patients undergoing major knee surgery under general anaesthesia combined with peripheral nerve blocks (femoral nerve block, combined femoral/sciatic nerve block or lumbar plexus block) received a single bolus injection of 300 or 400 mg prilocaine about 30 min before surgery via a catheter. The proper placement was verified using nerve stimulation via a stimulating catheter. Three hours after prilocaine injection, venous blood samples were drawn and methaemoglobin levels were measured by standard photometric technique. Data was subjected to a stepwise multiple regression analysis. Results: The mean methaemoglobin for all patients was 2.7% (range: 0.9–15.4%). A higher dose of prilocaine and younger age were the most important predictive factors for higher methaemoglobin formation. Female sex and to a lesser extent the use of high‐concentration/low‐volume prilocaine also increased methaemoglobin levels. These four factors of the model explain 36% of the total variance. Other investigated factors, including the patient’s height, weight, body mass index, the site of catheter insertion, the anaesthetist’s judgement concerning the difficulty of catheter placement, duration of catheter placement or an inadvertent puncture of a venous or arterial vessel, had no significant impact on the concentration of methaemoglobin. Conclusion: The use of prilocaine for regional block is safe, since the older patients who might be more susceptible to suffer from clinical symptoms of methaemoglobinaemia usually form less methaemoglobin. However, since prediction of high methaemoglobin levels is difficult, anaesthesiologists performing regional blocks in patients who might be jeopardized by a decreased oxygen transport capacity should avoid high doses of prilocaine.

Postoperative analgesia with parecoxib, acetaminophen, and the combination of both: a randomized, double-blind, placebo-controlled trial in patients undergoing thyroid surgery

BACKGROUND We assessed the analgesic efficacy of parecoxib, acetaminophen, and the combination of both compared with placebo in patients undergoing elective thyroid or parathyroid surgery. METHODS We randomized 140 patients to receive one of the following i.v. treatments using a double-blinded double-dummy technique: placebo, 80 mg 24 h(-1) parecoxib, 5 g 24 h(-1) acetaminophen, or 80 mg parecoxib plus 5 g acetaminophen. We provided rescue analgesia with piritramide delivered by a patient-controlled analgesia device. We measured opioid consumption and pain intensity over 24 h after operation. RESULTS Patient characteristic data, anaesthetic, and surgical characteristics of the patients in the four groups were similar. Parecoxib, acetaminophen, and the combination significantly reduced opioid requirements during 24 h after surgery [mean (sd) 12.5 (10.9) mg for parecoxib, 14.2 (12.3) mg for acetaminophen, and 11.9 (10.7) mg for combination] compared with placebo [23.5 (15.3) mg, P<0.05]. However, the combination of parecoxib and acetaminophen did not have any advantage over individual drugs in terms of opioid consumption in our trial (P>0.05). CONCLUSIONS Parecoxib and acetaminophen effectively reduce postoperative opioid requirements after thyroid or parathyroid surgery. The combination of these drugs is not associated with a further reduction in opioid consumption.

Anti‐emetic prophylaxis with oral tropisetron and/or dexamethasone

Background  The corticosteroid dexamethasone and the serotonine3‐antagonist tropisetron are both effective drugs for the prophylaxis of post‐operative nausea and vomiting (PONV) when given intravenously. The aim of this trial was to evaluate the oral use of both drugs as part of a routine oral premedication and to compare their single and combined effectiveness.

[Undesired side effects of tapentadol in comparison to oxycodone. A meta-analysis of randomized controlled comparative studies].

OBJECTIVE Tapentadol is a new centrally acting analgesic with a dual mode of action as an agonist of the µ-opioid receptor and as a norepinephrine reuptake inhibitor. The aim of the present study was to evaluate the results from randomized controlled trials investigating the relative amount of adverse effects using tapentadol or oxycodone for the treatment of pain. METHODS A quantitative systematic review was carried out according to the PRISMA recommendations on randomized controlled trials comparing tapentadol and oxycodone in pain treatment. The incidences of typical adverse side effects of opioid-based analgesic therapy (e.g. nausea, vomiting, obstipation or pruritus) were extracted and the pooled relative risks (RR) with corresponding 95% confidence intervals (CI) were calculated. RESULTS A total of 9 trials involving 7,948 patients were included and of these 2,810 patients were treated with oxycodone and 5,138 were treated with tapentadol in equivalent analgesic dosages as documented by an equivalent analgesic effect. The risk of typical opioid-based adverse effects, such as nausea (RR 0.61; 95% CI 0.57-0.66), vomiting (RR 0.50, 95% CI: 0.41-0.60), obstipation (RR 0.47, 95%-CI 0.40-0.56), dizziness (RR 0.86, 95% CI 0.78-0.95), somnolence (RR 0.76, 95% CI 0.67-0.86) and pruritus (RR 0.46, 95% CI 0.37-0.58) was reduced when tapentadol was used for analgesic treatment. These adverse effects were investigated in all nine trials. The risk for dryness of the mouth (6 trials, 6,218 patients, RR 1.79, 95% CI 1.40-2.29) and dyspepsia (1 trial, 646 patients, RR 2.75, 95% CI 1.09-6.94) was increased when tapentadol was used instead of oxycodone. There were no significant differences in the relative risk for any other investigated adverse effect such as dysentery, headache or fatigue. CONCLUSION The results show that using tapentadol significantly reduces the risk of the typical opioid-based adverse effects compared with oxycodone while providing equivalent analgesic treatment.

Unerwünschte Nebenwirkungen von Tapentadol im Vergleich zu Oxycodon

OBJECTIVE Tapentadol is a new centrally acting analgesic with a dual mode of action as an agonist of the µ-opioid receptor and as a norepinephrine reuptake inhibitor. The aim of the present study was to evaluate the results from randomized controlled trials investigating the relative amount of adverse effects using tapentadol or oxycodone for the treatment of pain. METHODS A quantitative systematic review was carried out according to the PRISMA recommendations on randomized controlled trials comparing tapentadol and oxycodone in pain treatment. The incidences of typical adverse side effects of opioid-based analgesic therapy (e.g. nausea, vomiting, obstipation or pruritus) were extracted and the pooled relative risks (RR) with corresponding 95% confidence intervals (CI) were calculated. RESULTS A total of 9 trials involving 7,948 patients were included and of these 2,810 patients were treated with oxycodone and 5,138 were treated with tapentadol in equivalent analgesic dosages as documented by an equivalent analgesic effect. The risk of typical opioid-based adverse effects, such as nausea (RR 0.61; 95% CI 0.57-0.66), vomiting (RR 0.50, 95% CI: 0.41-0.60), obstipation (RR 0.47, 95%-CI 0.40-0.56), dizziness (RR 0.86, 95% CI 0.78-0.95), somnolence (RR 0.76, 95% CI 0.67-0.86) and pruritus (RR 0.46, 95% CI 0.37-0.58) was reduced when tapentadol was used for analgesic treatment. These adverse effects were investigated in all nine trials. The risk for dryness of the mouth (6 trials, 6,218 patients, RR 1.79, 95% CI 1.40-2.29) and dyspepsia (1 trial, 646 patients, RR 2.75, 95% CI 1.09-6.94) was increased when tapentadol was used instead of oxycodone. There were no significant differences in the relative risk for any other investigated adverse effect such as dysentery, headache or fatigue. CONCLUSION The results show that using tapentadol significantly reduces the risk of the typical opioid-based adverse effects compared with oxycodone while providing equivalent analgesic treatment.

Vapocoolant Spray Versus Lidocaine Infiltration for Radial Artery Cannulation: A Prospective, Randomized, Controlled Clinical Trial

OBJECTIVES Local infiltration with lidocaine is a frequently used measure to prevent pain during arterial cannulation. Its administration is associated with pain. Vapocoolants like ethyl chloride or alkanes also affect rapid-onset anesthesia. However, their administration causes less discomfort compared with administration of lidocaine. The effectiveness of vapocoolants in mitigating discomfort associated with arterial cannulation never has been studied. The authors therefore compared vapocoolant with lidocaine for reducing discomfort caused by arterial cannulation. DESIGN Prospective, randomized, controlled study. SETTING University hospital, single center. PARTICIPANTS One hundred sixty adult patients requiring arterial cannulation before induction of general anesthesia for cardiac surgery or carotid endarterectomy. INTERVENTIONS Patients received either lidocaine infiltration or vapocoolant spray prior to arterial cannulation. Overall discomfort resulting from the whole procedure (applying local/topical anesthesia followed by arterial puncture) was rated on a 0 to 10 numerical rating scale. Puncture failure rate and time required for the intervention also were recorded. MEASUREMENTS AND MAIN RESULTS One hundred forty-three patients were included in the per-protocol analysis. Mean pain scores in the vapocoolant group were 3.4 (±1.58) compared with 4.5 (±2.29) in the lidocaine group (difference 1.1±0.33; p = 0.032; Mann-Whitney U-test). The higher puncture failure rate in the lidocaine group (n = 11 v 4) was not significant (p = 0.06; Fishers exact test). The time required for the intervention was longer in the lidocaine group (138±44 s v 128±44 s; p = 0.019; Mann-Whitney U-test). CONCLUSIONS Vapocoolant spray is an alternative to lidocaine infiltration to mitigate discomfort associated with arterial cannulation.

Stability‐indicating HPLC assays for the determination of piritramide and droperidol in PCA solution

What is known and Objective:  A mixture of morphine and droperidol is a well‐established antiemetic for reducing the risk of postoperative nausea and vomiting. A mixture of piritramide and droperidol has not yet been evaluated in this context. Our objectives were to develop a high‐performance liquid chromatographic assay for piritramide and droperidol in 0·9% saline, and to establish their stability under defined storage conditions.

Implementation of new standards in anaesthesia. Exemplified by the ad hoc introduction of desflurane in 10 German hospitals

BACKGROUND According to numerous pharmacoeconomic studies new anaesthesia techniques can improve recovery times and thus can have a positive economic impact on patient turnover. However, artificial study protocols do not always match real world situations and thus the practical impact of such studies remains unclear. MATERIAL AND METHODS At 10 hospitals exclusively using sevoflurane as a volatile anaesthetic, the ad hoc implementation of desflurane was studied with respect to post-anaesthetic recovery times (primary endpoint) and postoperative outcome measured by the Quality of Recovery Score- (QoR-)40, on the first postoperative day was investigated. Randomization of patients undergoing elective surgical procedures under general anaesthesia with sevoflurane (n=186) or desflurane (n=176) was started immediately after a period of a few days after introducing the new drug to all participants. Except for the volatile anaesthetic the anaesthetic procedure was performed according to local standing operating procedures. RESULTS All parameters indicating the immediate postanaesthetic recovery were superior in the patients receiving desflurane (mean±SD). Time to extubation was accelerated from 8.7±9.7 to 6.2±6.8 min. Times to recalling name and date of birth were accelerated by 2.6 and 3.8 min, respectively. Transferring the patients from the operating theatre to the post-anaesthetic recovery unit was 17.3±11.5 min after sevoflurane and 13.7±7.8 min after anaesthesia with desflurane. Eligibility for discharge according to a modified Aldrete score (White and Song 1999) was reached after 103±98 and 79±76 min, respectively. The postoperative recovery (QoR 40 questionnaire) did not differ 24 h later. DISCUSSION The implementation of a new drug (here: desflurane to substitute sevoflurane) can improve speed of recovery immediately after termination of anaesthesia even after a very short period of introducing the new technique but has no positive long term effects. Thus, the results of this trial performed under a real world scenario (health service research) without tight standardization by an artificial study protocol supports the results originating from randomized controlled clinical trials.

Implementierung neuer Standards in der Anästhesie

BACKGROUND According to numerous pharmacoeconomic studies new anaesthesia techniques can improve recovery times and thus can have a positive economic impact on patient turnover. However, artificial study protocols do not always match real world situations and thus the practical impact of such studies remains unclear. MATERIAL AND METHODS At 10 hospitals exclusively using sevoflurane as a volatile anaesthetic, the ad hoc implementation of desflurane was studied with respect to post-anaesthetic recovery times (primary endpoint) and postoperative outcome measured by the Quality of Recovery Score- (QoR-)40, on the first postoperative day was investigated. Randomization of patients undergoing elective surgical procedures under general anaesthesia with sevoflurane (n=186) or desflurane (n=176) was started immediately after a period of a few days after introducing the new drug to all participants. Except for the volatile anaesthetic the anaesthetic procedure was performed according to local standing operating procedures. RESULTS All parameters indicating the immediate postanaesthetic recovery were superior in the patients receiving desflurane (mean±SD). Time to extubation was accelerated from 8.7±9.7 to 6.2±6.8 min. Times to recalling name and date of birth were accelerated by 2.6 and 3.8 min, respectively. Transferring the patients from the operating theatre to the post-anaesthetic recovery unit was 17.3±11.5 min after sevoflurane and 13.7±7.8 min after anaesthesia with desflurane. Eligibility for discharge according to a modified Aldrete score (White and Song 1999) was reached after 103±98 and 79±76 min, respectively. The postoperative recovery (QoR 40 questionnaire) did not differ 24 h later. DISCUSSION The implementation of a new drug (here: desflurane to substitute sevoflurane) can improve speed of recovery immediately after termination of anaesthesia even after a very short period of introducing the new technique but has no positive long term effects. Thus, the results of this trial performed under a real world scenario (health service research) without tight standardization by an artificial study protocol supports the results originating from randomized controlled clinical trials.