Future of regional anaesthesia

A simple guide to regional anaesthesia

Regional anaesthesia is widely used in modern anaesthetic practice for perioperative and postoperative analgesia. In the operating theatre, regional anaesthesia is used both on its own and in combination with other techniques (general anaesthesia and sedation). Regional anaesthesia is now a core skill set in anaesthetic training. This article provides a basic outline of regional anaesthesia for surgeons and other non-anaesthetic staff working with anaesthetists, reviewing preparation, consent, basic and specialist equipment, central neuraxial blocks (spinal, epidural and caudal), trunk blocks, upper limb blocks (interscalene, supraclavicular, infraclavicular and axillary) and lower limb blocks (femoral, fascia iliaca, sciatic, popliteal and ankle). It also discusses the pharmacology of the agents used and common complications.

Analysis of the temporal regression of the QRS widening induced by bupivacaine after Intralipid administration. Study in an experimental porcine model

OBJECTIVE

The principal mechanism of cardiac toxicity of bupivacaine relates to the blockade of myocardial sodium channels, which leads to an increase in the QRS duration. Recently, experimental studies suggest that lipid emulsion is effective in reversing bupivacaine cardiac toxicity. We aimed to evaluate the temporal evolution of the QRS widening induced by bupivacaine with the administration of Intralipid.

MATERIAL AND METHODS

Twelve pigs were anesthetized with intravenous sodium thiopental 5mg kg(-1) and sevoflurane 1 MAC (2.6%). Femoral artery and vein were canalized for invasive monitoring, analysis of blood gases and determination of bupivacaine levels. After instrumentation and monitoring, a bupivacaine bolus of 4-6 mg kg(-1) was administered in order to induce a 150% increase in QRS duration (defined as the toxic point). The pigs were randomized into two groups of six individuals. Intralipid group (IL) received 1.5 mL kg(-1)of IL over one minute, followed by an infusion of 0.25 mL kg min(-1). Control group (C) received the same volume of a saline solution. The electrocardiographic parameters were recorded, and blood samples were taken after bupivacaine and 1, 5, 10 and 30 minutes after Intralipid/saline administration.

RESULTS

Bupivacaine (4.33±0.81 mg/kg in IL group and 4.66±1.15 mg/kg in C group) induced similar electrocardiographic changes in both groups; mean maximal percent increase in QRS interval was 184±62% in IL group, and 230±56% in control group (NS). Lipid administration reversed the QRS widening previously impaired by bupivacaine. After ten minutes of the administration of IL, the mean QRS interval decreased to 132±56% vs. 15±76% relative to the maximum widening induced by bupivacaine, in IL and C group, respectively.

CONCLUSION

Intralipid reversed the lengthening of QRS interval induced by the injection of bupivacaine. Time to normalization of electrocardiographic parameters can last more than 10 minutes. While the phenomena of cardiac toxicity persist, resuscitation measures and adequate monitoring should be continued until adequate heart conduction parameters are restored.

Ropivacaine attenuates endotoxin plus hyperinflation-mediated acute lung injury via inhibition of early-onset Src-dependent signaling

Background

Acute lung injury (ALI) is associated with high mortality due to the lack of effective therapeutic strategies. Mechanical ventilation itself can cause ventilator-induced lung injury. Pulmonary vascular barrier function, regulated in part by Src kinase-dependent phosphorylation of caveolin-1 and intercellular adhesion molecule-1 (ICAM-1), plays a crucial role in the development of protein-/neutrophil-rich pulmonary edema, the hallmark of ALI. Amide-linked local anesthetics, such as ropivacaine, have anti-inflammatory properties in experimental ALI. We hypothesized ropivacaine may attenuate inflammation in a “double-hit” model of ALI triggered by bacterial endotoxin plus hyperinflation via inhibition of Src-dependent signaling.

Methods

C57BL/6 (WT) and ICAM-1^−/− mice were exposed to either nebulized normal saline (NS) or lipopolysaccharide (LPS, 10 mg) for 1 hour. An intravenous bolus of 0.33 mg/kg ropivacaine or vehicle was followed by mechanical ventilation with normal (7 ml/kg, NTV) or high tidal volume (28 ml/kg, HTV) for 2 hours. Measures of ALI (excess lung water (ELW), extravascular plasma equivalents, permeability index, myeloperoxidase activity) were assessed and lungs were homogenized for Western blot analysis of phosphorylated and total Src, ICAM-1 and caveolin-1. Additional experiments evaluated effects of ropivacaine on LPS-induced phosphorylation/expression of Src, ICAM-1 and caveolin-1 in human lung microvascular endothelial cells (HLMVEC).

Results

WT mice treated with LPS alone showed a 49% increase in ELW compared to control animals (p = 0.001), which was attenuated by ropivacaine (p = 0.001). HTV ventilation alone increased measures of ALI even more than LPS, an effect which was not altered by ropivacaine. LPS plus hyperinflation (“double-hit”) increased all ALI parameters (ELW, EVPE, permeability index, MPO activity) by 3–4 fold compared to control, which were again decreased by ropivacaine. Western blot analyses of lung homogenates as well as HLMVEC treated in culture with LPS alone showed a reduction in Src activation/expression, as well as ICAM-1 expression and caveolin-1 phosphorylation. In ICAM-1^−/− mice, neither addition of LPS to HTV ventilation alone nor ropivacaine had an effect on the development of ALI.

Conclusions

Ropivacaine may be a promising therapeutic agent for treating the cause of pulmonary edema by blocking inflammatory Src signaling, ICAM-1 expression, leukocyte infiltration, and vascular hyperpermeability.

Pain management in patients with adolescent idiopathic scoliosis undergoing posterior spinal fusion: combined intrathecal morphine and continuous epidural versus PCA

STUDY DESIGN

A retrospective case-comparison study.

OBJECTIVE

Compare efficacy and safety of combined intrathecal morphine (ITM) and epidural analgesia (EPI) to that of conventional intravenous patient-controlled analgesia (IV-PCA) after posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Pain control after PSF in AIS has been managed traditionally with IV-PCA. More recently studies have shown improvement in pain control with the use of continuous EPI or intraoperative ITM. No studies to our knowledge have compared the use of both ITM and EPI analgesia to that of IV-PCA.

METHODS

An Institutional Review Board-approved retrospective case-comparison study was performed from 1989 to 2009 of all patients undergoing PSF for AIS. Patients received either IV-PCA or ITM/EPI. Daily pain scores were recorded along with total opioid and benzodiazepine use. Adverse events were recorded for all the patients.

RESULTS

A total of 146 patients were initially included in the study; 95 patients received ITM/EPI and 51 received IV-PCA as a historical control. Eight patients from the ITM/EPI group were excluded from the pain comparison portion of the study. There were no statistical differences in age, sex, weight, or hospital stay between the 2 groups. The ITM/EPI group had, on average, 1 additional level of fusion (P = 0.001). Daily average pain scores were lower in the ITM/EPI group on all hospital days, and statistically lower in days 1 and 3 to 5. Total opioid requirement was significantly lower in the ITM/EPI patients, although oral opioid use was higher among this group. Total benzodiazepine use was lower among the IV-PCA group. A total of 15.7% of the IV-PCA patients had bladder hypotonia, compared with 1.1% of the ITM/EPI group (P = 0.002). The rate of illeus was 15.7% in the IV-PCA patients and 5.7% in the ITM/EPI (P = 0.071). Respiratory depression was reported in 4 ITM/EPI patients, 0 in our PCA group. Technical catheter malfunction was reported in 8.5% of the EPI group.

CONCLUSIONS

The use of ITM/EPI after PSF for AIS is safe and effective, this methodology provided significantly lower pain scores and lowers total opioid use which can lead to urinary and bowel dysfunction.

The role of regional and neuroaxial anesthesia in patients with systemic sclerosis

Systemic sclerosis (SSc), previously known as progressive systemic sclerosis, is a form of scleroderma and a multisystem connective tissue disease which can impact on every aspect of anesthetic care, especially airway management. In this review we outline clinical manifestations and current medical treatment of the disease, and general principles of anesthetizing these patients. We focus on the role of regional anesthesia, including neuroaxial anesthesia, which may serve as a safe alternative to general anesthesia but can be technically challenging. We address concerns regarding abnormal responses to local anesthesia which have previously been reported in patients with SSc, and explore future developments in technology and pharmacology, which may enable regional anesthesia to be performed more successfully and with fewer complications.

A comparison of three methods of pain control for posterior spinal fusions in adolescent idiopathic scoliosis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To compare the efficacy of patient-controlled analgesia (PCA) with morphine alone, a single preoperative intrathecal morphine injection and PCA (IT/PCA), and epidural catheter infusion without PCA (EPI) for postoperative pain control after posterior spinal fusion (PSF) and segmental spinal instrumentation (SSI) in adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Postoperative pain control after PSF and SSI in AIS can be managed in different ways. EPI provides for a longer period of pain relief but is reliant on the correct placement and maintenance of the catheter in the epidural space. A single preoperative intrathecal morphine injection also provides for long acting analgesia. No direct comparison of these 3 methods of postoperative pain control has been reported.

METHODS

An IRB-approved retrospective chart review was performed at 2 institutions from 1997 to 2005. The medical record was reviewed to determine pain scores after surgery at multiple time periods. The 3 groups were compared using Student t test and chi and significance was defined as P < 0.05.

RESULTS

There was no statistical difference in the gender, age, magnitude of curve, or number of levels fused in the IT/PCA (N = 42), PCA (N = 41), or EPI (N = 55) groups. Postoperative pain scores were lowest in the IT/PCA group in the first 8 hours (P < 0.05) but the pain scores in the EPI group were then lower through 24 hours (P < 0.05). Total morphine use (mg/kg) was lower in the IT/PCA group compared with the PCA group at 12 hours and 24 hours (P = 0.0001). Return to solid food ingestion was quickest in the EPI group (2.0 days) followed by the IT/PCA (2.6 days) and PCA alone (3.2 days) (P < 0.002). Respiratory depression and transient neurologic change occurred most frequently in the EPI group (EPI 11/55 pts vs. 1/42 IT/PCA vs. 0/41 PCA P < 0.001). Pruritus was greatest in the epidural group (11/55 P < 0.05). There were no intraoperative somatosensory-evoked potential changes or permanent neurologic injury recorded in any group.

CONCLUSION

An EPI controls postoperative pain for the longest period of time and allows for a quicker return to consumption of solid foods. However, a single preoperative intrathecal morphine injection controls the pain equally for the first 24 hours with less pruritus and with less adverse events thus requiring less nursing and physician intervention after PSF and SSI in AIS. All methods were safe with no neurologic injury recorded.

Anaesthesia and analgesia: contribution to surgery, present and future

Anaesthetists provide comprehensive perioperative medical care to patients undergoing surgical and diagnostic procedures, including postoperative intensive care when needed. They are involved in the management of perioperative acute pain as well as chronic pain. This manuscript considers some of the recent advances in modern anaesthesia and their contribution to surgery, from the basic mechanisms of action, to the delivery systems for general and regional anaesthesia, to the use of new drugs and new methods of monitoring. It assesses the resulting progress in acute and chronic pain services and looks at patient safety and risk management. It speculates on directions that may shape its future contributions to the management of the patient undergoing surgery.

Trainingsmethode für Regionalanästhesisten

INTRODUCTION

Optimized training facilities are the key to efficient teaching of regional anesthesia.

MATERIAL AND METHODS

A combination of Thiel's embalming method, flap dissection and pulse simulation was offered to participants in several workshops on regional anesthesia. Tutors, experienced anesthetists and anatomists, evaluated the workshop and compared Thiel's method to classic formaldehyde conservation. Additionally both embalming methods were assessed with regard to the mechanical properties according to the requirements of regional anesthesia.

RESULTS

The evaluation showed high acceptance of the method offered in the workshop. In a comparison of fixation methods Thiel's method was generally preferred as it presented more similar conditions to living patients and almost ideal conditions for regional anesthesia.

CONCLUSION

The presented method is an optimized, strongly accepted teaching and training tool for teaching regional anesthesia.

Management of incomplete regional anaesthesia in Germany: results of a nation-wide survey

BACKGROUND

Regional anaesthesia (RA) provides well-defined benefits with known attendant risks. However, incomplete blockade may introduce unanticipated risks depending on the compensatory measures employed. Until now, no data were available characterizing the pattern of response of German anaesthesiologists in this situation. This study analyses interventions in response to incomplete RA in a nation-wide setting.

METHODS

A questionnaire was sent to every German anaesthesia department (n= 1381). Questions focused on interventions coping with an incomplete RA and differentiated between a pre- and a peri-surgical setting and measures to face pain outside the surgical field. If systemic supplementation was administered, we analysed the substances and characterized their influence on subsequent patient care.

RESULTS

Six hundred and sixty-seven questionnaires were returned anonymously, representing a return rate of 48.3%. If RA was incomplete before surgery, 56.8% of anaesthesiologists repeated peripheral blocks, 48.5% repeated epidural (EDA) and 60.4% repeated spinal anaesthesia (SPA). 56.9% of clinicians preferred an early switch to general anesthesia (GA). If RA was incomplete during surgery, 49.5% tended to switch early to GA, 13.9% made attempts to avoid this by intensive systemic supplementation. Benzodiazepines and opioids were the most commonly used substances. Pain or discomfort outside the surgical field was widely managed by intravenous supplementation (67.7%) and only 10.6% were willing to switch to general anaesthesia.

CONCLUSIONS

In Germany, anaesthesiologists manage incomplete RA using a widespread spectrum of measures. Some might introduce specific risks, which potentially outweigh the benefits of RA in comparison to GA techniques.

The addition of tramadol to morphine via patient-controlled analgesia does not lead to better post-operative pain relief after total knee arthroplasty

BACKGROUND

Tramadol is used as an analgesic in post-operative pain treatment. Intravenous tramadol is often combined with morphine to achieve better pain relief and less side-effects after orthopaedic surgery. However, the available evidence is insufficient to support this combination. For this reason, we conducted the present non-commercial, randomized, double-blind clinical trial.

METHOD

Sixty-three patients with osteoarthritis of the knee, selected for primary total knee arthroplasty (TKA), were randomized to receive saline or tramadol 100 mg/ml intravenously every 6 h during the first post-operative day (total, 400 mg/24 h). All patients had access to morphine via a patient-controlled analgesia (PCA) pump.

RESULTS

Neither during the 6 h after the first dose nor during the first post-operative day could we detect any statistically significant difference with regard to pain intensity, sedation and nausea between patients treated with tramadol and the placebo group. However, the withdrawal rate caused by insufficient pain relief was greater in the tramadol group (7/31) than in the saline group (2/32). This difference did not reach statistical significance. In the group of patients who remained in the study for 24 h ('per protocol'), those randomized to receive tramadol had a significantly (P < 0.05) lower morphine consumption (20 mg or 31%) than the placebo group.

CONCLUSION

Our study does not support the combination of tramadol and morphine via PCA for post-operative pain relief after primary TKA. In addition, our study indicates that morphine via PCA as the sole means of post-operative analgesia does not provide sufficient pain relief after TKA. Thus, other means of post-operative analgesia should be used following TKA.

Cervical epidural analgesia via a thoracic approach using nerve-stimulation guidance in adult patients undergoing total shoulder replacement surgery

BACKGROUND

Continuous cervical epidural anesthesia can provide excellent peri- and post-operative analgesia, although several factors prevent its widespread use. Advancing catheters from thoracic levels to the cervical region may circumvent these barriers, provided they are accurately positioned. We hypothesize that guiding catheters from thoracic to cervical regions using low-current epidural stimulation will have a high success rate and enable excellent analgesia in adults undergoing total shoulder arthroplasty.

METHODS

After Institutional Review Board approval, adult patients were studied consecutively. A 17-G Tuohy needle was inserted into the thoracic epidural space using a right paramedian approach with loss of resistance. A 20-G styletted epidural catheter, with an attached nerve stimulator, was primed with saline and a 1-10 mA current was applied as it advanced in a cephalad direction towards the cervical spine. Muscle twitch responses were observed and post-operative X-ray confirmed final placement. After a test dose, an infusion (2-8 ml/h) of ropivacaine 2 mg/ml and morphine 0.05 mg/ml (or equivalent) was initiated. Verbal analog pain scale scores were collected over 72 h.

RESULTS

Cervical epidural anesthesia was performed on 10 patients. Average current required to elicit a motor response was 4.8 +/- 2.0mA. Post-operative X-ray of catheter positions confirmed all catheter tips reached the desired region (C4-7). The technical success rate for catheter placement was 100% and excellent pain control was achieved. Catheters were positioned two to the left, four to the right and four to the midline.

CONCLUSION

This epidural technique provided highly effective post-operative analgesia in a patient group that traditionally experiences severe post-operative pain and can benefit from early mobilization.

How to teach regional anesthesia

PURPOSE OF REVIEW

The demand for peripheral nerve blocks and neuroaxial blocks from both patients and surgeons has increased over the last few years. This change in attitude towards regional anesthesia is prompted by the insight that adequate perioperative pain management leads to earlier ambulation, shorter hospital stay, reduced cost and increased patient satisfaction. To avoid serious complications of these techniques structured residency programs need to be available.

RECENT FINDINGS

Until 2004, the Residency Review Committee for Anesthesiology in the United States required a minimum of 50 epidurals, 40 spinals and 40 peripheral nerve blocks during residency. Similarly, the German Society for Anesthesia and Intensive Care required 100 neuroaxial blocks and 50 peripheral nerve blocks. In 2004 the American Society of Regional Anesthesia and Pain Medicine endorsed standardized guidelines for regional anesthesia fellowships which regulate the administrative, equipment and educational demands.

SUMMARY

This review introduces the reader to the different teaching methods available, including cadaver workshops, three-dimensional videoclips, video filming, ultrasound guidance and acoustic assist devices as well as demonstrating their advantages and disadvantages. Moreover, an overview is given of future residency training programs, which integrate administrative, material and educative demands as well as the teaching means into the daily clinical routine.