Anesthesia management for low-grade glioma awake surgery: a European Low-Grade Glioma Network survey

BACKGROUND

Awake surgery has become a key treatment of diffuse low-grade gliomas (DLGG) and is divided in three main phases: opening, tumor resection - during which the patient needs to be fully awake - and closure. The anesthetic management of awake neurosurgery is a challenge, and there are currently no guidelines.

OBJECTIVE

The objective of the survey was to explore differences and commonalities regarding the anesthetic management of awake DLGG surgery within the European Low-Grade Glioma Network (ELGGN) centers.

METHODS

A form that contained 14 questions about the anesthetic management was sent to 28 centers in May 2015.

RESULTS

Twenty centers responded. During the opening and closing non-awake periods, 56% of teams chose general anesthesia with mechanical ventilation for at least one period (asleep-awake-asleep, SAS protocol), and 44% monitored anesthesia care including sedation without mechanical ventilation (MAC protocol). In case of SAS, all the teams chose intravenous anesthesia, 82% used laryngeal mask instead of endotracheal intubation during the opening sequence, and 71% during closure. Local and regional anesthesia was practiced by all the teams. The most frequently reported cause of pain was dural and cerebral vessels manipulation (77%). Pain management was mostly based on paracetamol (70%) and remifentanil (55%).

CONCLUSION

Our survey showed that there was an equivalent proportion of centers using SAS or MAC protocols in the anesthetic management of awake surgery in ELGGN centers. The advantages and disadvantages of each anesthesia protocol were reviewed.

Ultrasound-Guided Regional Anaesthesia: Visualising the Nerve and Needle

Regional anaesthesia involves targeting specific peripheral nerves with local anaesthetic. It facilitates the delivery of anaesthesia and analgesia to an increasingly complex, elderly and co-morbid patient population. Regional anaesthesia practice has been transformed by the use of ultrasound, which confers advantages such as accuracy of needle placement, visualisation of local anaesthetic spread, avoidance of intraneural injection and the ability to accommodate for anatomical variation.An US beam is generated by the application of electrical current to an array of piezoelectric crystals, causing vibration and consequential production of high-frequency sound waves. The sound energy is reflected at tissue interfaces, detected by the piezoelectric crystals in the ultrasound probe, and most frequently displayed as a 2D image.Optimising image acquisition involves selection of the appropriate US frequency: this represents a trade-off between image resolution (better with high frequency) and tissue penetration/beam attenuation (better with low frequency). Altering alignment, rotation and tilt of the probe is often required to optimise the view as nerves are best visualised when the ultrasound beam is directly perpendicular to their fibres. Adjusting the focus, depth, and gain (brightness) of the image display can also help in this matter.Three key challenges exist in regional anaesthesia; image optimisation, image interpretation (nerve visualisation) and needle visualisation. There are characteristic sonographic appearances of the nerve structures for peripheral nerve blocks, as discussed in this chapter, and the above techniques can be used to enhance their appearance. Much research has been done, and is ongoing, with the aim of improving needle visualisation; this is also reviewed. Image interpretation requires the application of anatomical knowledge and understanding of the typical sonographic appearance of different tissues (as well as the needle). Years of practice are required to attain expertise, although it is hoped that continuing advances in nerve and needle visualisation, as described in this chapter, will expedite that process.

Intravenous Regional Anesthesia: A Historical Overview and Clinical Review

Intravenous regional anesthesia (IVRA) is an established, safe and simple technique, being applicable for various surgeries on the upper and lower limbs. In 1908, IVRA was first described by the Berlin surgeon August Bier, hence the name "Bier's Block". Although his technique was effective, it was cumbersome and fell into disuse when neuroaxial and percutaneous plexus blockades gained widespread popularity in the early 20^th century. In the 1960s, it became widespread, when the New Zealand anesthesiologist Charles McKinnon Holmes praised its use by means of new available local anesthetics. Today, IVRA is still popular in many countries being used in the emergency room, for outpatients and for high-risk patients with contraindications for general anesthesia. IVRA offers a favorable risk-benefit ratio, cost-effectiveness, sufficient muscle relaxation and a fast on- and offset. New upcoming methods for monitoring, specialized personnel and improved emergency equipment made IVRA even safer. Moreover, IVRA may be applied to treat complex regional pain syndromes. Prilocaine and lidocaine are considered as first-choice local anesthetics for IVRA. Also, various adjuvant drugs have been tested to augment the effect of IVRA, and to reduce post-deflation tourniquet pain. Since major adverse events are rare in IVRA, it is regarded as a very safe technique. Nevertheless, systemic neuro- and cardiotoxic side effects may be linked to an uncontrolled systemic flush-in of local anesthetics and must be avoided. This review gives a historical overview of more than 100 years of experience with IVRA and provides a current view of IVRA with relevant key facts for the daily clinical routine.

Modelling and characterisation of a ultrasound-actuated needle for improved visibility in ultrasound-guided regional anaesthesia and tissue biopsy

Clear needle visualisation is recognised as an unmet need for ultrasound guided percutaneous needle procedures including regional anaesthesia and tissue biopsy. With inadequate needle visibility, these procedures may result in serious complications or a failed operation. This paper reports analysis of the modal behaviour of a previously proposed ultrasound-actuated needle configuration, which may overcome this problem by improving needle visibility in colour Doppler imaging. It uses a piezoelectric transducer to actuate longitudinal resonant modes in needles (outer diameter 0.8-1.2mm, length>65mm). The factors that affect the needle's vibration mode are identified, including the needle length, the transducer's resonance frequency and the gripping position. Their effects are investigated using finite element modelling, with the conclusions validated experimentally. The actuated needle was inserted into porcine tissue up to 30mm depth and its visibility was observed under colour Doppler imaging. The piezoelectric transducer is able to generate longitudinal vibration with peak-to-peak amplitude up to 4μm at the needle tip with an actuating voltage of 20Vpp. Actuated in longitudinal vibration modes (distal mode at 27.6kHz and transducer mode at 42.2kHz) with a drive amplitude of 12-14Vpp, a 120mm needle is delineated as a coloured line in colour Doppler images, with both needle tip and shaft visualised. The improved needle visibility is maintained while the needle is advanced into the tissue, thus allowing tracking of the needle position in real time. Moreover, the needle tip is highlighted by strong coloured artefacts around the actuated needle generated by its flexural vibration. A limitation of the technique is that the transducer mode requires needles of specific lengths so that the needle's resonance frequency matches the transducer. This may restrict the choice of needle lengths in clinical applications.

Local Anesthetic-Induced Neurotoxicity

This review summarizes current knowledge concerning incidence, risk factors, and mechanisms of perioperative nerve injury, with focus on local anesthetic-induced neurotoxicity. Perioperative nerve injury is a complex phenomenon and can be caused by a number of clinical factors. Anesthetic risk factors for perioperative nerve injury include regional block technique, patient risk factors, and local anesthetic-induced neurotoxicity. Surgery can lead to nerve damage by use of tourniquets or by direct mechanical stress on nerves, such as traction, transection, compression, contusion, ischemia, and stretching. Current literature suggests that the majority of perioperative nerve injuries are unrelated to regional anesthesia. Besides the blockade of sodium channels which is responsible for the anesthetic effect, systemic local anesthetics can have a positive influence on the inflammatory response and the hemostatic system in the perioperative period. However, next to these beneficial effects, local anesthetics exhibit time and dose-dependent toxicity to a variety of tissues, including nerves. There is equivocal experimental evidence that the toxicity varies among local anesthetics. Even though the precise order of events during local anesthetic-induced neurotoxicity is not clear, possible cellular mechanisms have been identified. These include the intrinsic caspase-pathway, PI3K-pathway, and MAPK-pathways. Further research will need to determine whether these pathways are non-specifically activated by local anesthetics, or whether there is a single common precipitating factor.

A pilot in vitro evaluation of the "air test" for perineural catheter tip localization by a novice regional anesthesiologist

The "air test" is used clinically to infer perineural catheter location and has been recently evaluated for use by experts. However, its utility for practitioners with less experience is unknown. We tested the hypothesis that the air test, when performed by a novice regional anesthesiologist, will improve assessment of perineural catheter tip position in a validated porcine-bovine model and determined the test's positive and negative predictive values, sensitivity, and specificity for a novice. In contrast to the results of the expert study, the air test did not improve the novice's assessment of perineural catheter tip location over chance.

Visibility of ultrasound-guided echogenic needle and its potential in clinical delivery of regional anesthesia

OBJECTIVE

Ultrasound-guided regional anesthesia is recommended for nerve block due to its safety and reliability. Needle visualization is important when inserting needles into tissues in close proximity to target nerves. For safety reasons, the tip of the standard-type needle for application of nerve block is thinner than that of an interventional needle for insertion into intra-abdominal organs, and this makes it harder to determine its precise position. The purpose of this study was to evaluate the performance of an insulated echogenic needle under ultrasound guidance in phantoms and in the routine anesthetic management of patients undergoing elective surgery.

METHODS

Needles with a 21-G diameter were inserted into Blue PhantomTM (Advanced Medical Technologies, LLC, WA) and chicken breast phantoms at angles of 15, 30, 45, 60, and 75 degrees relative to the surface. The needle was scanned by ultrasound using a TiTANTM (SonoSite, WA, USA). Visualization was compared between an insulated needle with corner cube reflectors (CCR-type: Hakko, Japan) and an insulated standard needle (S-type: Hakko, Japan). Both types of needle were also used to deliver regional anesthesia in patients with an ASA classification of PS1-2 undergoing elective surgery.

RESULTS

The tip of CCR appeared as 3 bright points under ultrasound, and was more hyperechoic than S. The CCR-type needle was clearly visible under ultrasound at insertion angles of 15, 30, and 45 degrees, and was consistently more hyperechoic than S. However, at steeper angles of > 60 degrees, visibility was poorer. In delivering clinical regional nerve block, CCR was usually more hyperechoic than S, allowing the nerve block points targeted to be accessed with greater ease.

CONCLUSIONS

The better visibility of the tip of CCR indicates that it is superior to S in the clinical delivery of peripheral nerve block.

An efficient capacitive sensing scheme for an ophthalmic regional anesthesia training system

Ophthalmic regional blocks are critical preoperative procedures involving the insertion of a syringe needle into the orbital cavity at such a position and angle that akinesia and analgesia is achieved without damage or harm to the eye and its associated musculature. A training system that accurately represents the orbital anatomical features and provides qualitative feedback on the performed anesthetic technique, can be of immense help in reducing risks involved in regional block administration. In this paper, a training system that employs a special but simple capacitive sensing scheme has been developed. A rapid prototyped eye-model has been used to ensure anatomical accuracy. Capacitive transmitter electrodes placed on the orbital wall along the length of the extraocular muscles are excited with a special excitation sequence and the displacement current at the needle of the syringe is measured using simple electronic unit and a Data Acquisition System, enabling the developed Virtual Instrument to detect the depth of penetration and proximity of the syringe needle to the ocular muscles. Additionally, the system detects needle touch of the muscles accurately. The proposed electrode array system and excitation schemes have been validated on a prototype system thus demonstrating its usefulness for practical training purposes.

Simulators for training in ultrasound guided procedures

The four major categories of skill sets associated with proficiency in ultrasound guided regional anaesthesia are 1) understanding device operations, 2) image optimization, 3) image interpretation and 4) visualization of needle insertion and injection of the local anesthetic solution. Of these, visualization of needle insertion and injection of local anaesthetic solution can be practiced using simulators and phantoms. This survey of existing simulators summarizes advantages and disadvantages of each. Current deficits pertain to the validation process.

Needle echogenicity in sonographically guided regional anesthesia: blinded comparison of 4 enhanced needles and validation of visual criteria for evaluation

OBJECTIVES

Needle visualization is important for sonographically guided regional anesthesia procedures. Needle characteristics that improve needle visualization are therefore important to anesthesiologists. This study compared several echogenic needle designs by defining characteristics of needle echogenicity and assessing regional anesthesiologist preferences for these characteristics across various needle angles.

METHODS

Twelve blinded regional anesthesiologists graded 5 randomized block needles (1 nonechogenic control and 4 echogenic) on 4 predefined characteristics (overall brightness of the needle, overall clarity of the needle, brightness of the needle tip, and clarity of the needle tip). In-plane needle images in a gel phantom were obtained at 4 needle angles (15°, 30°, 45°, and 60°). Participants rated specific needle characteristics for each needle at each angle and then ranked their overall needle preferences.

RESULTS

Significant differences in all 4 needle characteristics were found across needle types (P< .01). Clarity of the needle tip was significantly associated with overall needle rank (P = .009). Other needle visualization characteristics were not significantly correlated with needle rank. The SonoPlex Stim needle (Pajunk Medical Systems, Tucker, GA) was rated highest in all 4 predefined needle characteristics as well as overall needle rank.

CONCLUSIONS

This study shows that anesthesiologists prefer certain visual characteristics of needles used in sonographically guided regional anesthesia procedures. Specifically, needle tip clarity most closely predicted clinician needle preferences. These results support the idea that all echogenic needle designs do not uniformly enhance needle visualization. Further studies are needed to determine whether needles with superior tip clarity predict not only clinician preferences but also improved sonographically guided regional anesthetic outcomes.

Echogenic regional anaesthesia needles: a comparison study in Thiel cadavers

Ultrasound guidance is now the standard procedure for regional nerve block in anesthesiology. However, ultrasonic visualisation of needle manipulation and guidance within tissues remains a problem. Two new echogenic needles (Pajunk and Braun) have been introduced to anesthesiology clinical practice but evaluation has been restricted to preserved animal tissue. In this study, the visibility of both echogenic needles was compared with a standard nonechogenic needle in a Thiel cadaver model. A total of 144 intramuscular injections were made in the upper arm in-plane and out-of-plane to the ultrasound beam at four angles (30°, 45°, 60° and 75°). The visibility of the needle was assessed by two independent, blinded observers using a 5-point Likert ordinal scale. Weighted κ for interobserver agreement was 0.77 (95% confidence interval [CI]: 0.68-0.86). The Pajunk echogenic needle was more visible than the Braun standard needle in-plane (p = 0.04), and the Braun standard and Braun echogenic needles out-of-plane (p = 0.02). Independent predictors of visibility using logistic regression were needle (p < 0.001) and plane of insertion (p = 0.08), receiver operator characteristic (ROC) area under the curve 0.90. In conclusion, the Pajunk echogenic needle offers the best visibility for ultrasound-guided regional anesthesia.

Evaluation of a new disinfection method for ultrasound probes used for regional anesthesia: ultraviolet C light

OBJECTIVES

Ultrasound-guided regional anesthesia is commonly used for block placement. At present, the risk of cross contamination from probes is not well documented. To avoid transmission of infectious agents, several methods have been used for probe disinfection and protection. The aim of this study was to evaluate the antibacterial efficacy of a new high-level disinfection method based on ultraviolet C (UV-C) light under routine conditions after block placement with an unprotected probe.

METHODS

The study was after approval by the local Ethics Committee. In the first part of the study, 15 ultrasound probes were exposed to a large inoculum of 3 bacteria. Ultraviolet C disinfection consisted of cleaning the probe with dry and disinfectant-impregnated paper followed by a 90-second UV-C disinfection cycle in a decontamination chamber. A protocol was established to retrieve the probe with sterile gloves after opening the door of the chamber. In the second part, 50 blocks were placed with ultrasound-guided regional anesthesia. The skin was first prepared with an antiseptic solution, and sterile gel was applied; no covers were used to protect the probes. The blocks were then disinfected with UV-C light. Bacteriologic samples were collected before and after the UV-C method and inoculated on chocolate agar plates.

RESULTS

During the first part of the study, all probes were infected after inoculation (>150 colony-forming units) but were considered sterile (<10 colony-forming units) after disinfection. During the second part of the study, all probes were considered sterile before and after disinfection.

CONCLUSIONS

Ultraviolet C disinfection seems relevant for ultrasound-guided regional anesthesia just before block placement. It offers simple, fast, and effective high-level disinfection. Moreover, this method should obviate the use of sterile probe covers, which can improve echogenicity.

[Sub-tenon block for ocular globe anesthesia: a review]

Sub-Tenon anesthesia is an effective, well-tolerated technique for surgery in the anterior or posterior compartments of the eye. The advantages of this block are comparable to those of peribulbar and retrobulbar anesthesia and complications are minimal. Sub-Tenon anesthesia provides better analgesia than akinesia. Most studies suggest that sub-Tenon anesthesia is a good technique to choose, given that potential adverse effects are fewer than for other regional blocks and analgesia and akinesia are superior.

VR-based training and assessment in ultrasound-guided regional anesthesia: from error analysis to system design

If VR-based medical training and assessment is to improve patient care and safety (i.e. a genuine health gain), it has to be based on clinically relevant measurement of performance. Metrics on errors are particularly useful for capturing and correcting undesired behaviors before they occur in the operating room. However, translating clinically relevant metrics and errors into meaningful system design is a challenging process. This paper discusses how an existing task and error analysis was translated into the system design of a VR-based training and assessment environment for Ultrasound Guided Regional Anesthesia (UGRA).

Introduction of continuous regional analgesia via wound catheters in a peripheral hospital

PURPOSE

To review the effectiveness of continuous regional analgesia (CRA) via wound catheters after abdominal surgery in a district general hospital (Wanganui, New Zealand).

METHODS

Retrospective review of postoperative analgesia after CRA via wound catheters was introduced (April 2008 to December 2008). Pain scores, HDU stay, opiate use and complications were recorded.

RESULTS

Fifty-four patients' notes have been reviewed after elective and emergency laparotomies. Twenty-seven had WC (± patient controlled analgesia [PCA]), 15 had PCA only, 12 had epidural (± PCA). Resting pain scores were nil or zero in 18/27 (66.7%) wound catheter, 9/15 (60%) PCA and 5/12 (41.7%) epidural patients. Moderate/severe pain on movement was scored in patients 5/27 (18.5%) with wound catheter, 6/15 (40%) with PCA, 5/12 (41.7%) with epidural catheters. A single PCA syringe lasted over 24 hours in 18/27 (66.7%) wound catheter, 6/15 (40%) PCA, and 5/8 (63%) epidural + PCA patients. Eight adverse effects were seen; 4 wound infections (2 wound catheter, 1 PCA, 1 epidural patient) and 4 blockages of epidural catheters in epidural group. No adverse effect was found directly related to the WC.

CONCLUSIONS

Continuous regional analgesia via wound catheters provides effective and safe postoperative analgesia for surgical patients in a small district general hospital. Used as part of a multimodal approach it allows easy step-down from HDU to surgical wards. This technique has been readily accepted over the year by theatre, HDU, ward, and anaesthetics colleagues.

[Nursing basics in anesthesia: material to carry out regional anesthesia technics]

Nursing career tend to specialize more each time in the different specialties, for this reason the introduction of the specialist nurse in anaesthesia required a specific knowledge on this medical discipline. The evolution of technologies applied to the design of new needles, echography machines and other equipment for regional anaesthesia techniques make essential to update of our knowledge in this area. This piece of work pretend to show the readers (nurses working in anaesthesia and others practitioners involved in surgical areas or pain management) a current view about the material and other instruments, mostly used in the different types of nerve blocks in regional anaesthesia. The aim of this, is provided an easy introduction of the regional anaesthesia to the junior practitioners, and updated evidence to the senior practitioner. The work is structured in a classic way: introduction, central blocks (subarachnoid and epidural), peripheral blocks, regional intravenous anaesthesia, eye block, asepsis and conclusions.

The learning process of the hydrolocalization technique performed during ultrasound-guided regional anesthesia

BACKGROUND

Because poor echogenicity of the needle remains a safety issue, we decided to analyze the learning process of the hydrolocalization technique (Hloc) performed to continuously identify needle-tip anatomical position during many ultrasound-guided regional anesthesia procedures.

METHODS

Ten senior anesthesiologists naïve to the Hloc agreed to participate in the study. They were requested to perform 40 out-of-plane (OOP) approach ultrasound-guided axillary blocks (AB) each using the Hloc. The Hloc, which is a needle-tip localization principle, was performed by means of repetitive injections of a small amount of a local anesthetic solution (0.5-1 ml) under an ultrasound beam. Details of the learning process and skill acquisition of the Hloc were derived from the following parameters: the duration of block placement, a measure of the perceived difficulty of needle-tip visualization, a measure of block placement difficulty, and the amount of local anesthetics solution required for the technique.

RESULTS

Four hundred ABs were performed. The success rate of an ultrasound-guided AB was 98%. The Hloc was successful in all patients. Skill acquisition over time of the Hloc was associated with a significant reduction of both the duration and the perceived difficulty of ABs placement. Apprenticeship data revealed that 20 blocks were required to successfully place AB within 5 min in most cases using the Hloc.

CONCLUSION

The Hloc performed during the OOP approach of ultrasound-guided regional anesthesia is a simple technique with a relatively short learning process feasible for efficient placement of ABs.

[A laryngeal mask as an instrument of ventilation support during regional anesthesia]

When the duration of limb segment replantation is more than 8-10 hours under nerve block anesthesia, prominent are the factors of the patient's lassitude and fatigue caused by position discomfort, the elimination of which and the possibility of uncontrolled motor activity of the patient require deep sedation or his/her unconsciousness. In this connection, a laryngeal mask (LM) has proven to be a convenient and reliable alternative to an endotracheal tube, which allows tracheal intubation to be avoided in most cases. Our clinical observations of the course of anesthesia in patients during carpal segment replantations of 14 hours or more in duration have demonstrated that the LM reliably ensures upper airways patency, adequate ventilation, and gas exchange throughout the surgery. An algorithm of switching patients to different assisted ventilation modes to rapidly restore adequate ventilation and gas exchange if drug-induced respiratory distress occurs during regional anesthesia has been tested during 120 emergency and elective anesthesias. Indications for the clinical use of a LM in patients who need emergency reparative operations using microsurgical techniques are warranted. Various actions of an anesthesiologist are proposed while using a LM in patients with limb segment replantation.

Ultraschallgezielte Anästhesie peripherer Nerven

Ultrasound-guided anaesthesia of peripheral nerves is a new challenge for anaesthesiologists. The number of ultrasound users in this field has increased over the last 10 years because of improved high frequency ultrasound technology and increased mobility of machines. There have been many publications on blocking procedures but many questions still remain unanswered on the practical aspects of ultrasound-guided techniques. Basic knowledge in ultrasound technology and image characteristics and a defined approach to blocking procedures to ensure sterile working conditions are necessary to guarantee optimal safety of patients. Furthermore economic questions and the implementation of a standardised education program are very important.

Does Interscalene Catheter Placement with Stimulating Catheters Improve Postoperative Pain or Functional Outcome After Shoulder Surgery? A Prospective, Randomized and Double-Blinded Trial

BACKGROUND

In this prospective, randomized, double-blind trial we investigated the use of stimulating catheters in patients during and after shoulder surgery; functional improvement being the primary outcome measurement.

METHODS

After eliciting an adequate muscular twitch at < or =0.5 mA nerve stimulation output, the perineural catheter was advanced either blindly (conventional catheter = CC group, n = 20) or guided by stimulation via the catheter (stimulating catheter = SC group, n = 20). A bolus of 40 mL prilocaine 1% and 10 mL ropivacaine 0.75% was injected, followed by a patient-controlled infusion of ropivacaine 0.2% (8 mL/h infusion rate, bolus 2 mL, lockout time 20 min).

RESULTS

Onset of motor block was faster in the SC group, whereas sensory block did not differ between groups. Median pain scores on two postoperative days were equal. Improvement of the objective shoulder function score (Constant Murley Score) 6 wk postoperatively was enhanced to a clinically relevant extent in the SC group compared to the CC group (P < 0.01).

CONCLUSIONS

We conclude that the use of a stimulating catheter results in a faster onset of motor block, unaltered postoperative pain, and a significantly improved functional outcome 6 wk after shoulder surgery.

Complications of regional anesthesia

PURPOSE OF REVIEW

The use of regional anesthesia, either alone or as an adjunct to general anesthesia, is at an all-time high. Demonstrated benefits include reduced side effects, more efficient use of facilities and enhanced patient satisfaction with the improved postoperative pain relief. New advances in equipment, techniques and medications have been incorporated over the past 10 years, and especially over the last 2 years. As the number of practitioners and procedures increase, the number of complications may rise as well.

RECENT FINDINGS

The specific issues of nerve damage, treatment of local anesthetic toxicity with lipid solutions and prevention of wrong-sided procedures are examined with special reference to recent publications.

SUMMARY

Specific needle shapes, appropriate pharmacologic resuscitation from intravascular injection of local anesthetics and institutional procedures to positively identify patients and the correct block location are all part of a strategy to minimize the occurrence of adverse outcomes and to mitigate the consequences of those adverse events when they do occur. More importantly, these are changes that can be instituted immediately with minimal expense to the institution and great benefit to the patient.

Ultrasonographic guidance in pediatric regional anesthesia Part 1: Theoretical background

Recent findings support the use of ultrasonographic guidance in pediatric regional anesthesia. This review article illustrates basic knowledge in physics of ultrasound and ultrasonographic appearance of neuronal structures, which are prerequisites for the safe application of this technique in daily clinical practice. A critical view on education and ethics in science should emphasize future developments in ultrasonography for pediatric regional anesthesia.

[Ultrasound-guided peripheral nerve blockade]

Without miniaturization resulting in affordable hand-held ultrasound systems, ultrasound-guided regional anaesthesia would not be practicable. Nowadays facilitation of nerve blockade by means of ultrasound is achievable even in remote locations. Non-traumatic technique, visualisation of nerves, surrounding structures and the ability to assess the spread of the injected local anaesthetic combined with a high and predictable success rate are the major advantages when ultrasound is used in regional anaesthetic practise. After a short recapitulation of physical principles related to ultrasound this article focuses on the specific features related to ultrasound-guided identification and blockade of peripheral nerves. Technical pitfalls and their implications for a successful nerve block are put into perspective. Ultrasound can be used to facilitate blockade of the upper and lower extremity. The advantages and limitations of the technique when applied to the classical approaches for blockade of the brachial plexus and the femoral and ischiadic nerve are discussed. Ultrasound-guided regional anaesthesia is a valuable tool to improve safety, success rate and patient comfort in daily anaesthetic practise.

[Stimulating catheters for regional anesthesia: considerations in routine clinical use]

The use of peripheral catheter techniques for regional anaesthesia and analgesia is quite common today. Although electrical nerve stimulation facilitates the correct placement of the insertion cannula, nobody knows where exactly the tip of the advanced catheter will be located after insertion. With the help of stimulation nerve catheters the stimulation of the target nerve via the tip of the catheter during insertion enables a placement nearby the nerve without additional devices. These new catheter systems require--in comparison to the conventional--a modified insertion technique. This article illustrates how to use these catheters in clinical practice and provides information about investigations to success rate and failure.

Regionalanästhesie - Zugangswege zum Plexus brachialis

Peripheral regional blocks are not only appropriate for intraoperative anaesthesia. More and more they become popular for postoperative analgesia after painful operations of the extremities. For this reason in this article only techniques are presented, which are suitable as well for a "single shot" block as for a continuous technique with an indwelling catheter. In detail the interscalene technique according to Meier, the infraclavicular block according to Kilka, Geiger, and Mehrkens (or alternatively according to Raj, modified by Borgeat) and the perivascular axillary brachial plexus block are described. The continuous technique of the block of the suprascapular nerve is very helpful in patients with chronic pain in the shoulder, if no surgery is performed. The authors are very interested in a praxis relevant description of the techniques including numerous "tips and tricks".

Regionalanästhesie - Regionalanästhesie und Analgesie für die Kniegelenksendoprothetik

Postoperative analgesia for total knee replacement with a continuous nerve catheter is more effective than any other form of systemic analgesia. For complete analgesia a combined technique of a femoral with a proximal sciatic nerve block is recommended. An easy and reliable way to achieve this is a femoral or a fascia iliaca compartment block together with a subgluteal sciatic nerve block.

Hygienemaßnahmen in der Anästhesie

Several reasons such as ignorance, convenience, or economical considerations might lead to disobeying basic hygiene measures in anaesthesia. The most important recommendations are for: 1. General anaesthesia: bacterial filters prevent breathing circuit contamination from patient's expiratory secretions. This way reprocessing of reusable components is required only once a day or in case an external contamination has occurred; 2. Neuraxial blockade: use of sterile gloves, a surgical face mask, and a sterile gown is recommended; 3. Intravenous anaesthesia: equipment not manufactured for re-use may not be used for more than one patient under any circumstances. One-way-valves do not securely prevent retrograde contamination of the infusion system. Do not use multi dose vials unless declared by manufacturer. Alcoholic hand disinfection is the most important measure in order to avoid nosocomial pathogen transmission and infection.

Future of regional anaesthesia

The development and refinement of regional anaesthetic techniques for various types of surgery, mainly obstetric, ophthalmic and orthopaedic surgery, and of continuous regional analgesia continues. Suitable analgesic drug mixtures, and concentrations, will be further tested in order to find the ideal analgesic regimen for each type of surgery and for the individual patient. No new local anaesthetics or equipment for clinical use are expected in the near future. Improvement therefore depends much on how the anaesthesiologists use the present drugs, needles, nerve detection devices, catheters and pumps. During training in regional anaesthesia for the speciality of anaesthesiology and intensive care medicine, it may suffice to concentrate only on certain common techniques such as epidural block, spinal block, axillary brachial plexus block, intravenous regional anaesthesia and femoral nerve block. Rare regional anaesthetic blocks and invasive techniques should be mastered and taught by specially trained regional anaesthesiology experts. In chronic pain, regional anaesthetic blocks with local anesthetics are not expected to play any major therapeutic role. However, nerve blocks can be useful for diagnostic purposes and in order to facilitate rehabilitation in chronic pain syndromes.

The delivery rate accuracy of portable infusion pumps used for continuous regional analgesia

Portable pumps used for local anesthetic infusion during continuous regional analgesia are gaining acceptance. These pumps are often used for ambulatory patients who are medically unsupervised throughout most of the infusion. However, the performance of these pumps, which infuse potentially toxic medication, has not been independently investigated. We investigated the flow rate accuracy, consistency, and profiles of various portable pumps often used for local anesthetic infusion during continuous regional analgesia. By using a computer/scale combination within a laboratory to record infusion rates, 6 pumps were tested with their flow regulators at expected (30 degrees-32 degrees C) and increased (34 degrees-36 degrees C) temperatures. Infusion rate accuracy differed significantly among the pumps, exhibiting flow rates within +/-15% of their expected rate for 18%-100% of their infusion duration. An increase in temperature also affected pumps to differing degrees, with infusion rates increasing from 0% to 25% for each model tested. These results suggest that factors such as flow rate accuracy and consistency, infusion profile, and temperature sensitivity should be considered when choosing and using a portable infusion pump for local anesthetic administration.

IMPLICATIONS

Portable pumps often used for local anesthetic infusion during continuous regional analgesia exhibit varying degrees of delivery rate accuracy and consistency. Furthermore, increases in temperature result in an increased infusion rate for various pumps investigated. These factors should be taken into consideration when choosing and using a portable infusion pump.

[Ultrasound in local anaesthesia. Part I: technical developments and background]

The localisation of the nerve to be blocked is one of the special challenges in local anaesthesia. Since the first time local anaesthesia procedures were carried out approximately 100 years ago, the basic limitations of this method have always been the unsatisfactory success rate and the specific risks involved. Even by variation of the access route to the various nerves and use of different identification methods, no ideal blockade technique has been found which allows a 100% success rate and at the same time reduces the risks to a minimum. The clinical introduction of various aids, such as nerve stimulation or Doppler sonography, have brought no statistically significant advantages despite showing clear improvements. In recent years there has been a trend towards local anaesthesia in perioperative care due to the proven advantages and range of possibilities. Several working groups have developed methods for the sonographic identification of nerves or the epidural space and to an exact placing of needles or catheters from the information obtained. In this way the application of catheters and the injection of local anaesthetic agents can be carried out in an accurate and controlled manner. Although sonography is a procedure which has been used in local anaesthesia for over 10 years, there are at present only few practising local anaesthetists who can use this method. However, interest in this method is growing especially due to the aspect of quality assurance. Organising committees have established that this method will be the future direction. Perhaps even the prediction of Alon P. Winnie for ultrasound-guided local anaesthesia will become true: "Sooner or later someone will make a sufficiently close examination of the anatomy involved, so that exact techniques will be developed."