Continuous Interscalene Brachial Plexus Blocks: An Anatomical Challenge between Scylla and Charybdis?

Brachial plexus blocks at the interscalene level are frequently chosen by physicians and recommended by textbooks for providing regional anesthesia and analgesia to patients scheduled for shoulder surgery. Published data concerning interscalene single-injection or continuous brachial plexus blocks report good analgesic effects. The principle of interscalene catheters is to extend analgesia beyond the duration of the local anesthetic's effect through continuous infusion, as opposed to a single injection. However, in addition to the recognized beneficial effects of interscalene blocks, whether administered as a single injection or through a catheter, there have been reports of consequences ranging from minor side effects to severe, life-threatening complications. Both can be simply explained by direct mispuncture, as well as undesired local anesthetic spread or misplaced catheters. In particular, catheters pose a high risk when advanced or placed uncontrollably, a fact confirmed by reports of fatal outcomes. Secondary catheter dislocations explain side effects or loss of effectiveness that may occur hours or days after the initial correct function has been observed. From an anatomical and physiological perspective, this appears logical: the catheter tip must be placed near the plexus in an anatomically tight and confined space. Thus, the catheter's position may be altered with the movement of the neck or shoulder, e.g., during physiotherapy. The safe use of interscalene catheters is therefore a balance between high analgesia quality and the control of side effects and complications, much like the passage between Scylla and Charybdis. We are convinced that the anatomical basis crucial for the brachial plexus block procedure at the interscalene level is not sufficiently depicted in the common regional anesthesia literature or textbooks. We would like to provide a comprehensive anatomical survey of the lateral neck, with special attention paid to the safe placement of interscalene catheters.

[Ultrasound-guided low-volume continuous cervical sympathetic nerve block for treatment of an electrical storm]. / Ultraschallgestützte kontinuierliche zervikale Sympathikusblockade mit Niedrigvolumina zur Therapie bei anhaltender ventrikulärer Tachykardie.

In addition to the treatment for complex regional pain syndrome (CRPS), the stellate ganglion block is a treatment option for refractory intermittent ventricular tachycardia (VT). Despite the use of imaging techniques, such as fluoroscopy and ultrasound, numerous side effects and complications have been reported. These are a result of the complex anatomical site and the volume of injected local anesthetics. This article reports on the catheter placement for continuous block of the cervical sympathetic trunk with high-resolution ultrasound imaging (HRUI) in a patient with intermittent VT. The tip of the cannula was placed on the anterior aspect of the longus colli muscle and 20 mg prilocaine 1% (2 ml) was injected. The VT stopped and a continuous infusion of 1 ml/h ropivacaine 0,2 % was started. Nevertheless, during the next hour the patient developed hoarseness and dysphagia, so that a block of the recurrent laryngeal nerve and the deep ansa cervicalis (C1-C3) was carried out. The infusion was paused and restarted later with 0.5 ml/h. The spread of the local anesthetic was controlled by ultrasound. Over the next 4 days the patient showed no VT or detectable side effects. After implantation of a defibrillator 1 day later the patient could then be discharged home on the following day. This case shows that the HRUI can be advantageously used in the catheter placement and also when adjusting the flow rate. In this way the risk of complications and side effects related to the puncture and local anesthetic volume can be reduced.

[Ultrasound-guided peripheral venepuncture under poor venous conditions]. / Ultraschallgesteuerte periphere Venenpunktion bei schlechtem Venenstatus.

Placement of a peripheral indwelling venous catheter is a routinely performed invasive procedure, in which complications are often underestimated. In difficult venous conditions multiple puncture attempts are often required, which are time consuming, unnecessarily painful for the patients and nevertheless not always successful. Due to the close anatomical relationship between superficial veins and peripheral nerves in the arm, puncture-related nerve injury is not uncommon. Despite limited data it could be shown that ultrasound-guided peripheral venepunctures are superior to traditional landmark techniques in terms of success rates, time saving, avoidance of complications and patient satisfaction. In order to successfully integrate the sonographic puncture technique for vascular access into routine processes, a structured training and further education are prerequisites. This must include anatomical knowledge, basic knowledge of ultrasound formation and training in sonographic needle guidance techniques.