Manuel Wenk

Impact of Epidural Analgesia on Mortality and Morbidity After Surgery Systematic Review and Meta-analysis of Randomized Controlled Trials

Objective:To quantify benefit and harm of epidural analgesia, compared with systemic opioid analgesia, in adults having surgery under general anesthesia. Background:It remains controversial whether adding epidural analgesia to general anesthesia decreases postoperative morbidity and mortality. Methods:We searched CENTRAL, EMBASE, PubMed, CINAHL, and BIOSIS till July 2012. We included randomized controlled trials comparing epidural analgesia (with local anesthetics, lasting for ≥24 hours postoperatively) with systemic analgesia in adults having surgery under general anesthesia, and reporting on mortality or any morbidity endpoint. Results:A total of 125 trials (9044 patients, 4525 received epidural analgesia) were eligible. In 10 trials (2201 patients; 87 deaths), reporting on mortality as a primary or secondary endpoint, the risk of death was decreased with epidural analgesia (3.1% vs 4.9%; odds ratio, 0.60; 95% confidence interval, 0.39–0.93). Epidural analgesia significantly decreased the risk of atrial fibrillation, supraventricular tachycardia, deep vein thrombosis, respiratory depression, atelectasis, pneumonia, ileus, and postoperative nausea and vomiting, and also improved recovery of bowel function, but significantly increased the risk of arterial hypotension, pruritus, urinary retention, and motor blockade. Technical failures occurred in 6.1% of patients. Conclusions:In adults having surgery under general anesthesia, concomitant epidural analgesia reduces postoperative mortality and improves a multitude of cardiovascular, respiratory, and gastrointestinal morbidity endpoints compared with patients receiving systemic analgesia. Because adverse effects and technical failures cannot be ruled out, individual risk–benefit analyses and professional care are recommended.

Clonidine as an adjuvant to local anesthetics for peripheral nerve and plexus blocks: a meta-analysis of randomized trials.

The effect of adding clonidine to local anesthetics for nerve or plexus blocks remains unclear. The authors searched for randomized placebo-controlled trials testing the impact of adding clonidine to local anesthetics for peripheral single-injection nerve or plexus blocks in adults undergoing any surgery (except eye) without general anesthesia. Twenty trials (1,054 patients, 573 received clonidine) published 1992–2006 tested plexus (14 brachial, 1 cervical) and nerve blocks (2 sciatic/femoral, 1 midhumeral, 1 ilioinguinal/iliohypogastric, 1 ankle). Clonidine doses ranged from 30 to 300 μg; most patients received 150 μg. Clonidine prolonged the duration of postoperative analgesia (weighted mean difference 122 min; 95% confidence interval [CI] 74–169), sensory block (weighted mean difference 74 min; 95% CI 37–111), and motor block (weighted mean difference 141 min; 95% CI 82–199). In a subgroup of patients receiving an axillary plexus block, these effects were independent of whether clonidine was added to an intermediate or a long-acting local anesthetic. Clonidine increased the risk of arterial hypotension (odds ratio 3.61; 95% CI 1.52–8.55; number-needed-to-harm 11), orthostatic hypotension or fainting (odds ratio 5.07; 95% CI 1.20–21.4; number-needed-to-harm 10), bradycardia (odds ratio 3.09; 95% CI 1.10–8.64; number-needed-to-harm 13), and sedation (odds ratio 2.28; 95% CI 1.15–4.51; number-needed-to-harm 5). There was a lack of evidence of dose-responsiveness for beneficial or harmful effects. Clonidine added to intermediate or long-acting local anesthetics for single-shot peripheral nerve or plexus blocks prolongs duration of analgesia and motor block by about 2 h. The increased risk of hypotension, fainting, and sedation may limit its usefulness. Dose-responsiveness remains unclear.

Opioids added to local anesthetics for single-shot intrathecal anesthesia in patients undergoing minor surgery: a meta-analysis of randomized trials

Summary Morphine, and to a lesser extent fentanyl, added to intrathecal bupivacaine prolong postoperative analgesia. With morphine, the risk of respiratory depression cannot be ruled out. Abstract Opioids are widely used as additives to local anesthetics for intrathecal anesthesia. Benefit and risk remain unclear. We systematically searched databases and bibliographies to February 2011 for full reports of randomized comparisons of any opioid added to any intrathecal local anesthetic with the local anesthetic alone in adults undergoing surgery (except cesarean section) and receiving single‐shot intrathecal anesthesia without general anesthesia. We included 65 trials (3338 patients, 1932 of whom received opioids) published between 1983 and 2010. Morphine (0.05–2 mg) and fentanyl (10–50 μg) added to bupivacaine were the most frequently tested. Duration of postoperative analgesia was prolonged with morphine (weighted mean difference 503 min; 95% confidence interval [CI] 315 to 641) and fentanyl (weighted mean difference 114 min; 95% CI 60 to 168). Morphine decreased the number of patients needing opioid analgesia after surgery and decreased pain intensity to the 12th postoperative hour. Morphine increased the risk of nausea (number needed to harm [NNH] 9.9), vomiting (NNH 10), urinary retention (NNH 6.5), and pruritus (NNH 4.4). Fentanyl increased the risk of pruritus (NNH 3.3). With morphine 0.05 to 0.5 mg, the NNH for respiratory depression varied between 38 and 59 depending on the definition of respiratory depression chosen. With fentanyl 10 to 40 μg, the risk of respiratory depression was not significantly increased. For none of these effects, beneficial or harmful, was there evidence of dose‐responsiveness. Consequently, minimal effective doses of intrathecal morphine and fentanyl should be sought. For intrathecal buprenorphine, diamorphine, hydromorphone, meperidine, methadone, pentazocine, sufentanil, and tramadol, there were not enough data to allow for meaningful conclusions.

Effects of acute postoperative pain on catecholamine plasma levels, hemodynamic parameters, and cardiac autonomic control.

Summary Measurements of hemodynamic, endocrine, and autonomic parameters are not useful as surrogates to estimate the severity of acute postoperative pain in the clinical setting. Abstract Postoperative pain is often stated to be a significant contributor to a sympathetic stress response after surgery. However, hardly any evidence has been published to support this assumption. Hence it was the aim of this trial to investigate the relationship between postoperative pain and hemodynamic, endocrine, and autonomic parameters. A total of 85 postoperative patients in the recovery room were repeatedly asked to rate their pain on a numeric rating scale (NRS). Concurrently, the parameters of heart rate variability (HRV) were analysed, and mean arterial pressure (MAP), heart rate (HR) and respiration rate (RR) were recorded. Pain was categorized into no, mild, moderate, and severe. Blood samples were taken for epinephrine (EPI) and norepinephrine (NE) plasma level assessment at the time of recovery room admission and discharge, and each time pain was found decreased in categorized severity. A total of 239 pain readings were obtained. None of the investigated parameters correlated with NRS scores. NE was higher at NRS 5 to 10 vs. NRS 0 to 4 (mean [SEM]: 1009 [73] pg/mL vs. 872 [65] pg/mL; P < 0.01). This was also found for MAP, but not for EPI or the parameters of HRV, HR, and RR. In contrast to common belief, the severity of postoperative pain does not appear to be associated with the degree of sympathetic stress response after surgery, and other factors such as surgical trauma may be more important. Importantly, the absence of signs of sympathetic stimulation cannot be seen as a guarantee for the absence of significant pain.

Adenosine A1 but not A2a receptor agonist reduces hyperalgesia caused by a surgical incision in rats: a pertussis toxin-sensitive G protein-dependent process.

Background:Activation of A1 adenosine receptors (A1Rs) causes antinociception after nerve injury and inflammation. However, the role of A2a adenosine receptors (A2aRs) for pain processing is less clear. In the current study, the authors investigated the role of spinal adenosine A1Rs and A2aRs for the maintenance of mechanical hyperalgesia in an animal model for postoperative pain. Methods:Rats with intrathecal catheters were anesthetized and underwent plantar incision. Spontaneous pain behavior and withdrawal threshold to punctuate stimulation were measured before and after administration of intrathecal R-phenylisopropyl-adenosine (R-PIA; A1R agonist), 2-w p-2-carbonyl-ethyl-phenylethylaminox-5X-N-ethylcarboxami-doadenosine (CGS21680; A2aR agonist), or vehicle. In separate groups of animals, the effects of pertussis toxin, forskolin, glibenclamide, 4-aminopyridine, tetraethylammonium, apamin, charybdotoxin, or margatoxin on R-PIA–induced antinociception were examined. Results:Intrathecal administration of 5 nmol R-PIA but not 10 nmol CGS21680 decreased nonevoked spontaneous pain behavior. Furthermore, intrathecal administration of R-PIA but not of CGS21680 increased withdrawal thresholds after incision. Pretreatment with pertussis toxin and administration of forskolin, glibenclamide, 4-aminopyridine, and tetraethylammonium inhibited R-PIA–induced antinociception. In addition, intrathecal administration of apamin, charybdotoxin, or margatoxin did not modify mechanical hypoalgesia mediated by R-PIA. Conclusions:Spinal A1Rs but not A2aRs play an important role in the maintenance of nonevoked and evoked pain behaviors after an incision. Furthermore, A1R-induced spinal antinociception is mediated by interactions with pertussis toxin–sensitive G proteins. In addition, the opening of adenosine triphosphate–sensitive K channels but not of calcium-activated potassium channels and voltage-gated Kv1.3 or Kv1.6 channels contribute to the antinociceptive effect of A1R agonists.

Perioperative pain management after thoracotomy

Purpose of review Perioperative acute pain and the development of persistent pain after thoracotomy are major problems severely affecting health-related quality of life. This review examines and highlights recent strategies and advances in perioperative pain management in this field. Recent findings Despite the fact that thoracic epidural analgesia (TEA) is considered the ‘gold standard’ of perioperative care after thoracotomy, other local and regional techniques have emerged within recent years and seem to become valid alternatives to TEA. The use of continuous paravertebral blockade, in particular, may provide similar analgesia and fewer adverse effects than TEA. Multimodal systemic approaches, including the use of ketamine and gabapentinoids are being investigated as well as the effect of surgical techniques and adjuvant therapies such as transcutaneous electrical nerve stimulation on post-thoracotomy pain. Summary Even though thoracotomy is associated with significant postoperative complications, a growing understanding of the underlying pathophysiology and advances in multimodal pain therapy concepts in this specific group of patients are promising improved postoperative outcomes and potential reduction of the incidence of persistent pain.

Combination of a reduced dose of an intrathecal local anesthetic with a small dose of an opioid: A meta-analysis of randomized trials

&NA; Adding an opioid to a reduced dose of an intrathecal local anesthetic decreases the risk of local anesthetic–related adverse effects without compromising analgesia. &NA; We tested whether the combination of a reduced dose of a local anesthetic (LA) with an opioid compared with a standard dose of the same LA alone guaranteed adequate intraoperative anesthesia and postoperative analgesia and decreased LA‐related adverse effects. We systematically searched (to November 2012) for randomized comparisons of combinations of a reduced dose of an LA with a concomitant opioid (experimental) with a standard dose of the LA alone (control) in adults undergoing surgery with single‐injection intrathecal anesthesia without general anesthesia. We included 28 trials (1393 patients). In experimental groups, the median decrease in LA doses was 40% (range, 12%–70%). There was no difference between experimental and control groups in the need for intraoperative opioids or general anesthesia for failed block or in the duration of postoperative analgesia. With experimental interventions, there was evidence of a reduction in the duration of motor blockade postoperatively (average, −50 minutes), time to discharge from hospital or PACU (−33 minutes), time to ambulation (−28 minutes), and time to urination (−14 minutes). There was also evidence of a decrease in the risk of shivering (risk ratio [RR]: 0.26; 95% confidence interval [CI]: 0.12–0.56), nausea (RR: 0.45; 95% CI: 0.31–0.66), and arterial hypotension (RR: 0.52; 95% CI: 0.35–0.78). The risk of pruritus was increased (RR: 11.7; 95% CI: 6.2–21.9). Adding an opioid to a reduced dose of an intrathecal LA can decrease LA‐related adverse effects and improve recovery from the spinal block without compromising intraoperative anesthesia or duration of postoperative analgesia.

Feasibility and efficacy of preoperative epidural catheter placement for anterior scoliosis surgery.

Background:Postoperative pain control via thoracic epidural catheters (TECs) is an important aspect of postoperative care, and ample evidence highlights its positive physiologic effects and superiority to intravenous analgesia. If epidural catheters for postoperative pain relief are used in scoliosis surgery, current practice is the intraoperative placement of the TEC by the surgeon because preoperative placement is considered challenging and dangerous. On the basis of magnetic resonance imaging of scoliotic spines, the authors developed a technique for preoperative placement of TEC and investigated its safety and feasibility. Methods:Patients undergoing anterior scoliosis surgery were included, who received preoperative placement of TEC. Postoperative pain, problems associated with the TEC placement, possible side effects, radiographic data, and insertion levels of the TEC were noted. Results:The apex vertebra was identified as a possible site for TEC placement due to dural sac shift leaving a wider epidural space on the convex side. Scoliosis-induced rotation of the vertebrae required realignment of the needle toward the convex side. Sixty patients were included. The success rate for TEC placement was 96.6%: one failed attempt, one catheter placed intrapleurally, and one patient with Horner syndrome. Seven percent of patients required additional rescue analgesia. All other patients had pain scores within acceptable limits (Visual Analogue Scale <5). Conclusions:The authors have demonstrated that it is possible to insert a TEC in patients with scoliotic spines with a high degree of success using a redesigned approach and thus provide adequate postoperative analgesia with a single epidural catheter. However, precautions have to be taken.

Simulation for anesthesia in obstetrics

Simulation has become a major player in the medical world. Still way behind other high-risk industries, simulation is being increasingly accepted and finds its ways into many clinical areas. Simulation offers the possibility to train individual skills as well as to evaluate performance, provide group crisis management training or even investigate the safety of installed systems and algorithms without risking patients life. Obstetric units and labor suites have been identified as high-risk areas in the hospital setting and can be challenging environments for the anesthesiologist. Simulators can be used to improve communication skills and workload distribution, and specifically drill for obstetric-relevant crisis scenarios. However, it remains unclear how well these trainings do transfer into clinical performance and improved patient outcome. Being a relevant cost factor, simulation will have to provide answers to these questions; hence, more research is needed in the future.

Creation of a head and face protection device for children undergoing procedures in prone position

Background:  Positioning the head of patients undergoing procedures in lateral or prone position remains a difficult task for the anesthesiologists. Associated risks have attracted increasing attention because they range from minor facial soft tissue injuries to catastrophic complications such as stroke or postoperative blindness. Earlier, we reported on the use of a boxing sports helmet for simple and easy positioning of the head. However, as available helmets are limited in sizes and materials, that system is not easily transferable to children. Therefore, we sought to create a face and head protection device for children undergoing procedures in prone position.