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."