I. Rundshagen

A directional needle improves effectiveness and reduces complications of microcatheter continuous spinal anaesthesia

The present prospective randomized study compares the impact of two different spinal needle designs — non-directional versus directional — on the effectiveness of continuous spinal anaesthesia provided via a microcatheter in orthopaedic patients. Using the midline approach, a 28-gauge spinal catheter was inserted either through a 22-gauge Quincke needle (nondirectional, Group 1, n = 21) or a 22-gauge Sprotte needle (directional, Group 2, n = 21) under standardized conditions. The incidence of technical difficulties and postoperative complaints, onset time of analgesia at the level of T10 and dose requirement of plain bupivacaine 0.5% were recorded. Postoperatively, the subarachnoid position of the catheters was radiographically evaluated. There was a higher incidence of technical problems during catheter insertion in Group 1 compared with Group 2 (71% vs 19%, P < 0.05). Onset time of analgesia was shorter (P < 0.05) and anaesthetic dose requirement was lower in patients in Group 2 than in Group 1. While 40% of the catheters were found in a caudal position in Group 1, all catheters were in a cranial position or at the level of the puncture site in Group 2 (P < 0.05). There was no difference in the incidence of postoperative complaints between the groups. The faster onset of analgesia and lower dose requirement of local anaesthetics associated with a lower incidence of technical problems suggest that there is greater effectiveness and safety when microcatheters are inserted using directional needles rather than non-directional needles.RésuméCette élude randomisée compare en chirurgie orthopédique l’impact de deux modèles d’aiguille rachidienne — non directionnel versus directionnel — au regard de l’efficacité de la rachianesthésie continue réalisée avec un microcathéter. Par approche médiane, une cathéter rachidien 28 G est inséré à travers une aiguille Quincke 22G (modèle non-directionnel, Groupe 1, n = 21) ou Sprotte 22G (modèle directionnel, Groupe 2, n = 21) sous des conditions standardisées. On enregistre l’incidence des difficultés d’ordre technique et des doléances postopératoires, le délai de l’installation de l’analgésie au niveau T10 et la dose requise de bupivacaïne 0,5%. Après la chirurgie, la position sous-arachnoïdienne du cathéter est déterminée par radiographie. L’incidence des problèmes d’ordre technique au moment de l’insertion du cathéter est plus élevée dans le Groupe 1 que dans le Groupe 2 (71% vs 19% P < 0,05). L’installation de l’analgésie est plus courte (P < 0,05) et la dose anesthésique requise est plus basse dans le Groupe 2 que dans le Groupe 1. Alors que 40% des cathéters se retrouvent en position caudale dans le Groupe 1, tous les cathéters du Groupe 2 se retrouvent en position céphalique ou au niveau de la ponction dans le Groupe 2 (P < 0,05). L’incidence des doléances postopératoires est la même pour les deux groupes. Le plus court délai d’installation de l’analgésie et la diminution de la dose nécessaire d’anesthésique local associés à l’incidence moindre de problèmes techniques suggèrent que la sécurité et l’efficacité sont supérieures quand des microcathéters sont insérés à l’aide d’aiguilles directionnelles plutôt que non directionnelles.

Cortical arousal in critically ill patients: an evoked response study

Abstract Objective: Assessing the level of sedation in critically ill patients remains a challenge for the intensivist in order to avoid over or under-sedation. Clinical scoring systems may fail in patients with concomitant neurological disorders or requiring muscle relaxants. We evaluated auditory (AER) and median nerve somatosensory evoked responses (MnSSER) in critically ill patients sedated with sufentanil and propofol, in order to quantify the level of sedation during therapeutic interventions. Design: Prospective clinical study. Setting: Anaesthesiological intensive care unit (ICU) in a university hospital. Patients and participants: Thirty-two patients following major abdominal or thoracic surgery requiring sedation during their stay on the ICU. Interventions: During physiotherapy and following nursing care (tracheal suctioning) AER and MnSSER were recorded. The level of sedation was evaluated clinically in relation to vital parameters. Data were analysed by multivariate analyses of variance (Hotellings T2), Friedman test. Measurements and results: In comparison to baseline levels the AER latency Nb decreased, while the amplitude NaPa increased during physiotherapy and after tracheal suctioning (p<0.001). In contrast, the MnSSER latency P25 decreased and the amplitude P25N35 increased after tracheal suctioning only (p≤0.001). Clinical sedation scores decreased and mean arterial blood pressure increased during physiotherapy and nursing care. Conclusions: Changes of AER or MnSSER waves indicated cortical arousal in ICU patients during nursing care and physiotherapy. Further studies with evoked responses are recommended to evaluate whether bolus injections of sedatives and/or analgesics reduce cortical arousal and thereby minimise the patient’s stress during nursing care.

Continuous spinal analgesia: Comparison between patient-controlled and bolus administration of plain bupivacaine for postoperative pain relief

Background and Objectives. Adequate postoperative pain relief has been achieved in orthopedic patients by subarachnoid bolus administration of plain bupivacaine. This prospective randomized study compares bolus injections of bupivacaine with a patient controlled infusion via subarachnoid 28‐gauge microcatheters for postoperative analgesia after elective hip replacement. Methods. Forty‐two patients (mean age, 69 ± 11 years) were randomly allocated to one of two groups. Group 1 patients received a constant subarachnoid infusion of 0.6 mg/h of bupivacaine by a patientcontrolled device and were allowed to self‐administer 0.6 mg every 30 minutes Group 2 patients received a nurse‐administered bolus of 3.75 mg of plain bupivacaine on request. Pain was assessed by patients and nurses by a visual analog scale (VAS) every hour. The degree of motor block and the level of analgesia were documented every 4 hours. Hemodynamic and respiratory parameters were recorded hourly. Differences between groups were tested by analysis of variance for repeated measurement. Results. Technical problems occurred in six patients were more frequent in group 1 but none in group 2. Patient‐controlled analgesia resulted in lower pain scores than bolus application during 18 postoperative hours (VAS score 19 ± 19 mm in group 1 and 39 ± 30 mm in group 2; P < .01). Lower total doses of bupivacaine were required in group 1 (17.6 ± 4 mg) than in group 2 (22.3 ± 7 mg: P < .05). The groups did not differ with respect to the degree of motor block (Bromage score 3.5 ± 0.5), the sensory level (L1‐2 ± 1), or hemodynamic or respiratory parameters. Conclusion. In spite of a higher incidence of technical problems, patient‐controlled analgesia with a continuous background infusion via microspinal catheters provides more effective postoperative analgesia, without hemodynamic or respiratory side effects, than bolus administration.

Subarachnoid and intravenous PCA versus bolus administration for postoperative pain relief in orthopaedic patients

Background: Patient‐controlled analgesia (PCA) with intravenous piritramide and subarachnoid bupivacaine was studied during postoperative pain management in comparison with nurse‐administered bolus injections.

[Drug addiction and anaesthesia: most popular recreational drugs in Germany and anaesthesiological management of drug addicts].

Drug addicts need special anesthesiological care due to their co-morbidities, their modified need for analgesics and anesthetics and/or their specific substitution therapies. In spite of the high incidence of addiction worldwide controlled studies and evidence based recommendations for the anaesthesiological management of the patients are missing. The perioperative care is not the treatment of addiction, on the contrary the specific aspects of a chronic disease have to be accepted. Equally important perioperative treatment strategies for the management of drug addicts include: 1. stabilisation of the physical dependence by substitution therapies. 2. avoidance of distress or craving. 3. perioperative stress relief. 4. strict avoidance of inadequate analgesic treatment. 5. postoperative optimization with regional or systemic analgesia with non-opioids, opiods and co-analgesics. 6. consideration of specific physical or psychological comorbidities. Inadequate analgesic treatment is known to be responsible for relapses into addiction and has strictly to be avoided. This holds true even for people with long term drug abstinence.

Median nerve evoked responses and explicit memory during recovery from isoflurane/nitrous oxide anesthesia

Purpose: To evaluate median nerve somatosensory evoked responses during recovery from anesthesia in relation to clinical findings.Methods: Twenty-two gynecologic patients received isoflurane in nitrous oxide for anesthesia. Midlatency somatosensory evoked responses (N20, P25, N35, P45, N50) were recorded the day before surgery (AWAKE), during steady state anesthesia (STABLE), and every five minutes after discontinuation of anesthesia until the patients were able to name a shown object correctly (RECOVERY). Next day the patients were questioned with a structured interview about their explicit memory of the immediate recovery period and classified into groups: No-MEM (no memory) and MEM (memory). Multivariate analysis of variance compared electrophysiological parameters at the different time points and between the two memory groups.Results: During STABLE isoflurane/N2O anesthesia, all cortical amplitudes were reduced (P≤0.003) and all latencies were prolonged compared with AWAKE (P<0.001). At RECOVERY the latencies N35, P45, N50 remained prolonged (P≤0.001), while the amplitudes N20P25 and P45N50 were reduced in comparison to AWAKE (P≤0.02). The latencies P45 (48±8 vs 61±9 msec) and N50 (67±12 vs 81±10 msec) were shorter in the patients of the group MEM (P≤0.03) at RECOVERY.Conclusion: The reversibility of anesthetic induced changes in amplitudes and latencies of median nerve somatosensory evoked responses reflected clinical awakening during emergence from isoflurane/nitrous oxide anesthesia. In the patients who had recall for the immediate recovery period, the reversibility of anesthetic induced changes of components P45 and N50 was faster than in patients without recall.RésuméObjectif: Évaluer les potentiels évoqués somesthésiques du nerf médian en relation avec les constatations cliniques pendant la récupération de l’anesthésie.Méthode: Vingt-deux patientes de gynécologie ont reçu une anesthésie avec un mélange d’isoflurane et de protoxyde d’azote. Les potentiels évoqués somesthésiques de milatence (N20, P25, N35, P45, N50) ont été enregistrés le jour précédant l’opération (VIGILE), pendant une période stable de l’anesthésie (STABLE) et toutes les cinq minutes après l’arrêt de l’anesthésie jusqu’à ce que les patientes puissent nommer correctement un objet désigné (RÉCUPÉRATION). Le jour suivant, on a interrogé les patientes lors d’une rencontre structurée au sujet de leur mémoire explicite de la période de récupération immédiate. On les a ensuite réparties en groupes: No-MEM (sans mémoire) et MEM (mémoire). L’analyse de variance multivariée a permis de comparer les paramètres électrophysiologiques entre les deux groupes à différents moments.Résultats: Pendant l’action STABLE de l’anesthésie à l’isoflurane/N2 O, toutes les amplitudes corticales ont été réduites (P≤0,003) et tous les temps de latence ont été prolongés, comparés aux données VIGILES (P<0,001). Pendant la RÉCUPÉRATION, les temps de latence N35, P45, N50 sont demeurés longs (P≤0,001), tandis que les amplitudes N20P25 et P45N50 ont été réduites, comparées aux amplitudes VIGILES (P≤0,02). Les temps de latence P45 (48±8vs 61±9 msec) et N50 (67±12 vs 81±10 msec) ont été plus courts chez les patientes du groupe MEM (P≤0,03) à la RÉCUPÉRATION.Conclusion: La réversibilité des changements, induits par l’anesthésique, d’amplitude et de temps de latence des potentiels évoqués somesthésiques du nerf médian correspondait au réveil clinique pendant la récupération de l’anesthésie à l’isoflurane/N2O. Chez les patientes qui ont eu une mémoire immédiate de la récupération, la réversibilité des changements provoqués par l’anesthésique des composantes P45 et N50 a été plus rapide que chez les patientes sans souvenir.

Pharmakologische Grundlagen der postoperativen Schmerztherapie Epidurale Opioidapplikation

ZusammenfassungIn dieser Kurzübersicht wird der Stellenwert der alleinigen epiduralen Opioidapplikation im Vergleich zur intravenösen Applikation hinsichtlich Analgesiequalität und Nebenwirkungsrate dargestellt. Im einzelnen werden folgende Kapitel abgehandelt:•*Pharmakologische Grundlagen•*Morphin•*Hydromorphon•*Alfentanil•*Fentanyl•*Sufentanil•*Zukünftige Entwicklungen.AbstractThe administration of epidural opioids is alternatively used in the management of postoperative analgesia. However, the administration is associated with side effects, including respiratory depression, somnolence and pruritus. A rational opioid selection between the hydrophilic and lipophilic opioids morphine, hydromorphone, alfentanil, fentanyl and sufentanil is discussed in this mini-review. Thus, the administration of the lipophilic opioid sufentanil might has some advantages. Notwithstanding, epidural opioid administration alone offers no marked clinical advantages compared to the intravenous route. In future, reduced doses of lipophilic opioids and local anaesthetics like bupivacaine 0.05–0.1% may provide benefits over the use of either drug alone and may offer marked clinical advantages over the intravenous route of opioids alone. The same holds true for α2-adrenoceptor agonists as adjuvants. However, multicenter dose-ranging studies are necessary to determine both the ideal concentrations of the drug combinations and the general outcome. Moreover, we must also determine cost effectiveness for our postoperative analgesic techniques.

A Directional Needle Improves Effectiveness and Reduces Complications of Microcatheter Continuous Spinal Anaesthesia

The present prospective randomized study compares the impact of two different spinal needle designs--non-directional versus directional--on the effectiveness of continuous spinal anaesthesia provided via a microcatheter in orthopaedic patients. Using the midline approach, a 28-gauge spinal catheter was inserted either through a 22-gauge Quincke needle (non-directional, Group 1, n = 21) or a 22-gauge Sprotte needle (directional, Group 2, n = 21) under standardized conditions. The incidence of technical difficulties and postoperative complaints, onset time of analgesia at the level of T10 and dose requirement of plain bupivacaine 0.5% were recorded. Postoperatively, the subarachnoid position of the catheters was radiographically evaluated. There was a higher incidence of technical problems during catheter insertion in Group 1 compared with Group 2 (71% vs 19%, P < 0.05). Onset time of analgesia was shorter (P < 0.05) and anaesthetic dose requirement was lower in patients in Group 2 than in Group 1. While 40% of the catheters were found in a caudal position in Group 1, all catheters were in a cranial position or at the level of the puncture site in Group 2 (P < 0.05). There was no difference in the incidence of postoperative complaints between the groups. The faster onset of analgesia and lower dose requirement of local anaesthetics associated with a lower incidence of technical problems suggest that there is greater effectiveness and safety when microcatheters are inserted using directional needles rather than non-directional needles.