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Background Peripheral regional anesthesia catheters offer the possibility of sufficient continuous pain therapy with reduction or avoidance of opioids and their side effects, such as drowsiness, nausea and vomiting. In addition, sleep quality, patient satisfaction, mobilization and rehabilitation can be improved. 1 2 A major advantage is the gradual control of the blockade by flexible adjustment of the local anesthetic (LA) dose with the aim of differentiated analgesia while avoiding motor blocks. Most single-shot blocks on extremities or the trunk can be prolonged by catheters. Useful indications are expected severe pain that lasts longer than 24 hours postoperatively or due to injuries, as the effect of single-shot blocks rarely lasts longer. In particular, patients with a high risk of developing chronic pain or opioid dependence, or multimorbid and elderly patients for whom opioids should be avoided because of possible respiratory depression and vigilance reduction, can benefit. However, the technically complex implementation, the higher material and human resource consumption, block failures and possible complications due to infections, prolonged motor block or catheter malposition limit the utilization of catheters. Some studies show a very limited or even no superiority of catheter procedures over systemic multimodal pain therapy in terms of analgesia quality and opioid consumption.3 4 One cause may be primary or secondary failure of the catheter procedure. Beside technical problems (occlusion or disconnection of the catheters), a suboptimal dosage of LA and leakage, primary misplacement or secondary migration of the catheters play a significant role. The latter can also lead to serious complications with fatal patient outcomes due to intrapleural, epidural, intrathecal or intravascular misplacement5 6 or cause specific side effects such as Horner´s syndrome, hoarseness or dyspnea.4 7 Primary misplacement occurs when the usually blindly advanced catheter is not correctly positioned in the target area. Reliable data on the frequency are not available in the literature. In a cadaver study primary malposition was described in 80% of cases.8 Secondary dislocation is usually caused by catheter migration within the tissue (up to 70%) or, very rarely, by the catheter slipping out (< 3%) at the insertion site.9 Unfortunately, primary and secondary malposition within the tissue cannot be detected from the outside, which presumably leads to reduced perception and underreporting of the problem. For the safe and effective application of the continuous catheter procedures, standardized processes are necessary, which include care by a 24/7 available pain service, the selection of suitable application techniques and catheter materials as well as proper local anesthetic delivery regimes. Tips and tricks to make catheters work Avoiding primary dislocations The ultrasound-guided insertion of regional anesthesia catheters is associated with a higher success rate and fewer accidental vascular punctures compared to the landmark technique with peripheral nerve stimulation10 and should therefore be standard. The decisive factor is the verification of the correct catheter position in the target area. Despite echo-optimized catheter materials direct sonographic imaging of the catheter is challenging. In contrast to rigid cannulas, catheters are curling and less straight in the tissue. Therefore, catheters are less congruent with the ultrasound beam plane.2 Sonographic imaging of fluid spread, injected through the catheter, allows determination of optimal location of the catheter openings near the target structure.9 The application of 1–2 ml saline bolus is usually sufficient. When using LA, possible side effects should be considered in case of malposition (e.g. intravascular in the vertebral artery, intrathecal or near the stellate ganglion in the case of interscalene blocks). The alternative injection of air or agitated liquid can deteriorate the image quality due to artifacts in the tissue. An additional application of color Doppler sonography can clarify the perception of the spread of the fluid bolus in the tissue. In addition, primary catheter malposition depends largely on the application technique and the catheter material used. For example, the in-plane technique and rigid catheters promote dislocations, as the catheter is very often advanced past the target.11 However, so-called overshooting is not excluded even with the out-of-plane technique when using steep puncture angles. Flexible catheters or self-coiling catheters allow the catheter to roll up or curl in the target area as soon as the catheter exits the cannula tip. Thus, primary misplacements can be almost prevented.12 In any case, the catheter position should be confirmed after placement by ultrasound imaging. In the case of a suboptimal position or malposition, the catheter must be corrected, usually by retracting the overshoot catheter. After withdrawal, however, the catheter is often only just 1–2 cm within the target area. In these cases, there is a high risk of migration due to further slipping back of the catheter due to tissue movement when the patient is mobilized. In doubt of adequate catheter performance, verification of the catheter position by ultrasound can be repeated as often as necessary. Avoiding secondary catheter migration Only a few studies have examined the position of catheters over time. In volunteers, secondary catheter migration in the tissue occurred in femoral nerve blocks in 25% and interscalene blocks in 5% within 6 hours after catheter placement in out-of-plane technique. However, subjects with BMI > 30 kg/m2 were excluded. In clinical studies, a significantly higher secondary dislocation rate was found in various nerve blocks.9 13 14 These dislocations usually occur on the day of surgery during repositioning in the PACU and rise up to 60% on the first postoperative day.9 The quality of pain therapy is significantly worse with dislocated catheters.9 Also here, the out-of-plane technology and flexible as well as self-coiling catheters seem to offer advantages in terms of a significantly reduced rate of catheter migrations. The reason for this is that the catheter can be reliably placed adjacent to the target structure with a longer section and is therefore more robust against retraction by tissue movement. Avoiding dislocation at insertion site Dislocation at insertion site seems an overestimated problem. In the literature the rate is usually far below 3%. There is little evidence for better fixation of catheters with skin adhesives, tunneling and anchoring devices. However, further studies are needed comparing several fixation methods. Avoiding leakage at insertion site Regional anesthesia catheter techniques are often associated with leakage which may cause more frequent change of dressings and dislodgements at insertion site. Catheter over the needle techniques decrease the rate of leakage. However, this advantage never could be translated to a better catheter performance regarding dislocation rate or quality of pain management. An alternative approach to diminish leakage is sealing the insertion site with skin glue. Optimal regime of LA infusion In a meta-analysis from 2020 programmed intermittent bolus (PIB) regime showed moderate superiority in comparison to a continuous infusion whereas patient controlled bolus was not. Beyond that, also patient satisfaction improved and opioid consumption decreased. This result is mostly confined to lower limb and truncal blocks. The effect of improved pain management was greater between 24 and 48 hours postoperatively. Considering the high number of dislocated catheters postoperatively this result suggests PIB regime might compensate dislocations, since a LA bolus more likely approaches the targeted nerve over a particular distance within the tissue in contrast to a continuous infusion. All bolus regimes lowered LA consumption. To maximize the utility of bolus application multi-orifice catheters are recommended. Flow from all orifices of multi-hole catheters depends on flow rate. Continuous infusion will deliver only a single hole, most likely the proximal one. Thus, for spread from all orifices a bolus application is required. More recent studies showed conflicting results regarding better pain management by PIB. However, the majority of this studies did not use multi-orifice catheters. Nevertheless, most studies confirmed the decrease of LA dose using bolus application. The heterogeneity of catheter types, applied block and catheter insertion techniques impede clear recommendations of optimal LA-dosage. Prevention of Infections Catheter associated infections occur up to 3% depending on the site of insertion. Risk factors are prolonged catheter duration > 48 h, frequent change of dressing and absence of antibiotic prophylaxis and patient related factors like obesity and diabetes. Apart from respecting the hygiene guidelines for aseptic catheter placement tunneling of catheters, single shot antibiotic and removal of catheters as soon as practical are proper strategies to lower infections rate. Therefore, catheter dedicated to long duration should be tunneled. Summery Catheter techniques for continuous peripheral regional anesthesia provide excellent quality of pain management as long as we ensure correct catheter placement avoiding dislocations and infections. Utilization of ultrasound not only for placement but also for confirmation of proper catheter location adjacent to the target structure is a key element. There is little evidence to promote a universally applicable infusion regime. The combination of multi-orifice catheters with PIB seems to show moderate favors especially in terms of decreased LA consumption.References Richman JM, Liu SS, Courpas G, et al. Does continuous peripheral nerve block provide superior pain control to opioids? A meta-analysis. Anesth Analg. 2006;102:248–57.Ilfeld BM. Continuous peripheral nerve blocks: an update of the published evidence and comparison with novel, alternative analgesic modalities. Anesthesia and Analgesia 2017;124:308–335.Fisker AK, Iversen BN, Christensen S, et al. Combined saphenous and sciatic catheters for analgesia after major ankle surgery: a double-blinded randomized controlled trial. Can J Anaesth. 2015;62(8):875–82.Rhyner P, Cachemaille M, Goetti P, et al. Single-bolus injection of local anesthetic, with or without continuous infusion, for interscalene brachial plexus block in the setting of multimodal analgesia: a randomized controlled unblinded trial. Reg Anesth Pain Med. 2024;49:313–319.Gaus P, Kutz PH, Bachtler JA, et al. [cave: interscalene catheters]. Anaesthesist 2017;66:961–968.Souron V, Reiland Y, Traverse AD, et al. Interpleural migration of an interscalene catheter. Anesth Analg. 2003;97(4):1200–1201.Fredrickson MJ, Leightley P, Wong A, et al. An analysis of 1505 consecutive patients receiving continuous interscalene analgesia at home: a multicentre prospective safety study. Anaesthesia 2016;71:373–399.Luyet C, Herrmann G, Ross S, et al. Ultrasound-guided thoracic paravertebral puncture and placement of catheters in human cadavers: where do catheters go? Br J Anaesth. 2011;106(2):246–54.Nickl R, Vicent O, Mueller T, et al. Impact of self-coiling catheters for continuous popliteal sciatic block on postoperative pain level and dislocation rate: a randomized controlled trial. BMC Anesthesiol. 2022;22(1):159.Schnabel A, Meyer-Frießem CH, Zahn PK, et al. Ultrasound compared with nerve stimulation guidance for peripheral nerve catheter placement: a meta-analysis of randomized controlled trials. British Journal of Anaesthesia 2013;111(4):564–72.Ilfeld BM, Fredrickson MJ, Mariano ER. Ultrasound-guided perineural catheter insertion: three approaches but few illuminating data. Reg Anesth Pain Med. 2010;35:123–126.Luyet C, Seiler R, Herrmann G, et al. Newly designed, self-coiling catheters for regional anesthesia-an imaging study. Reg Anesth Pain Med. 2011;36:171–176.Fujino T, Yoshida T, Kawagoe I, et al. Migration rate of proximal adductor canal block catheters placed parallel versus perpendicular to the nerve after total knee arthroplasty: a randomized controlled study. Reg Anesth Pain Med. 2023;48:420–424.Hauritz RW, Pedersen EM, Linde FS, et al. Displacement of popliteal sciatic nerve catheters after major foot and ankle surgery: a randomized controlled double-blinded magnetic resonance imaging study. Br J Anaesth. 2016;117:220–227.