Sciatic Nerve Block: a Useful Procedure for Diabetic Foot Surgery

Sciatic nerve block: A useful procedure for diabetic foot surgery Florian Heid, Robert Kampka, Gunther Pestel, Tim Piepho Article points 1. Patients requiring surgery The range of comorbidities experienced by people who require for the management of lower-limb surgery to manage diabetic foot disease are many. diabetic foot ulceration These comorbidites make the undertaken of general anaesthesia have a range of comorbidites that increase both difficult and places them at high risk of complications during the risks associated with surgery or in the immediate post-operative period. In this article the general anaesthesia. authors present a description of a peripheral nerve block procedure 2. The authors describe the use of sciatic nerve block as an alternative to general anaesthesia in patients undergoing lower- as an alternative to general limb surgery. Two case reports are also presented. anaesthesia. 3. A range of benefits to the eople with diabetic foot disease by electric nerve stimulation. The electrical patient are associated with regularly have severe comorbidities nerve stimulator (we use Stimuplex HNS eliminating the need for ® general anaesthesia in the P resulting in a high-risk profile for 11 ; Braun, Germany) produces an electrical presence of comorbidites. anaesthesia (American Diabetes Association, current that depolarises the nerve membrane 4. The authors suggest that 2003; Prompers et al, 2007). General and causes contraction of the effector those involved in diabetic anaesthesia and neuroaxial blockade (e.g. muscles of the relevant area. This confirms foot surgery consider spinal anaesthesia) may impair hemodynamic the proximity of the needle to the nerve. the use of nerve block stability. In people with diabetes who require Foot flexion at 0.1 ms and 0.4 mA indicates techniques as an alternative to general anaesthesia for podiatric surgery, peripheral nerve blocks adequate motor response and 40 mL of suitable patients. targeting at the sciatic nerve may be a useful local anaesthetic (e.g. ropivacaine 0.5% or alternative to general anaesthesia (Horlocker lidocaine 1.5%) are injected. If technical Keywords et al, 2006; Kocum et al, 2010). equipment and expertise are present, the - Amputation The authors provide a detailed description sciatic nerve may also be localized by - Comorbidity of the sciatic nerve block technique, and two ultrasound. - General anaesthesia case reports. Some regions of the lower leg belong - Nerve block to the saphenous nerve, which is the Practical procedure terminal branch of the femoral nerve. In While in supine position, the sciatic nerve order to achieve complete anaesthesia of is identified by electric nerve stimulation the lower leg, this nerve has to be blocked through a lateral approach with an insulated by additional 10 mL of local anaesthetic needle being inserted at the middle of (e.g. ropivacaine 0.5% or lidocaine 1.5%). the patients’ thigh (Figure 1). The correct Because the saphenous nerve only consists Author details can be found position of the needle (we use NanoLine 22 g of sensory fibres, electric nerve stimulation on the last page of this article. × 80 mm; Pajunk®, Germany) is confirmed may result in painful paraesthesia and is 124 The Diabetic Foot Journal Vol 15 No 3 2012 Sciatic nerve block: A useful procedure for diabetic foot surgery counterproductive. It is sufficient to inject Figure 1. Patient into the subcutaneous wall reaching from the position and needle tuberositas tibiae to the medial caput of the insertion for a sciatic gastrocnemius muscle (Figure 2). However, nerve block. the saphenous nerve can also be identified by ultrasound. Sufficient surgical anaesthesia is achieved 10–15 minutes after completion of injection. Characteristics of the block are related to the type of local anaesthetic used; lidocaine blocks have a fast onset and last from 2 to 3 hours, while ropivacaine blocks have a slower onset but regularly last >10 hours (Heavner, 2007). It is therefore Figure 2. The suggested that lidocaine and ropivacaine saphenous nerve is be combined to achieve both fast onset and block by injecting a a long duration. With a sufficient block, subcutaneous wall from additional post-operative pain control can the tuberositas tibia usually be dispensed with. [1] to the medial caput Using this block technique does not of the gastrocnemius impair the patient's protective reflexes (e.g. proven a useful addition to the management muscle [2]. coughing, swallowing), meaning that there is of some patients requiring surgery to manage no need for post-operative fastening and, for diabetic foot disease. The following case this reason, may make inpatient glycaemic reports illustrate the benefits of peripheral control more manageable. nerve blocks in this patient group. Case studies Case 1 As outlined before, diabetic patients A 72-year-old man was scheduled for regularly suffer from severe comorbidities, below-knee amputation due to infected which contribute to a high risk profile diabetic foot ulceration. The patient according to American Society of had long-standing insulin-dependent Anesthesiologists patient classification status diabetes (IDDM), renal insufficiency and III (severe systemic disease – i.e. definite severe coronary artery disease. He had a functional impairment [e.g. diabetes and history of myocardial infarction during a angina with relatively stable disease, but femoro–popliteal bypass surgery, which requiring therapy]) or IV (severe systemic led to intraoperative cardiopulmonary disease that is a constant threat to life [e.g. resuscitation. Given the patient's history diabetes and angina and chronic heart general anaesthesia was not recommended. failure; patient has dyspnea on mild exertion Due to absolute arrhythmia associated with and chest pain]; American Society of atrial fibrillation, he was anticoagulated with Anesthesiologists, 2012). high-dose enoxaparin and therefore spinal Hence, surgical procedures to manage anaesthesia was contraindicated. diabetic foot disease should be undertaken Following discussion, the patient with a careful consideration of the consented to regional anaesthesia and the anaesthetic techniques available. Regrettably, authors' team blocked the sciatic and the there is a widely held belief – among both saphenous nerve as described above. Beside patients and healthcare professionals – light sedation with 0.5 mg of midazolame he that all surgical procedures require general received no other systemic substance. anaesthesia. In the authors' practice, the The surgery was uneventful with a heart nerve block anaesthesia described above has rate between 60 and 80 beats/min and a 126 The Diabetic Foot Journal Vol 15 No 3 2012 Sciatic nerve block: A useful procedure for diabetic foot surgery noninvasive blood pressure of 130/60 mmHg l Preserving cardiopulmonary integrity, throughout. Postoperatively the patient was which is negatively influenced by positive- transferred to his normal ward to take lunch. pressure ventilation during general At 1-year follow-up the patient was doing anaesthesia (Pinsky, 1994). well, with no major documented events. l Negating the need for anaesthetic agents that reduce vascular tone and increase the Case 2 need for vasopressive substances, which A 77-year-old man with a history of long- may impair capillary blood flow. standing IDDM, renal insufficiency and l Insufficient metabolic and excretory arterial hypertension, was scheduled for capacities may cause extended effects of forefoot amputation due to infected diabetic muscle relaxants, inhalants and opioids, foot ulceration. The patient's left ventricular thereby impairing the early postoperative ejection fraction was significantly reduced recovery period (Bower et al, 2012). The (15%). Spinal anaesthesia (with possibly latter two additionally reduce the integrity deleterious preload reduction) and general of the immune system (Brand et al, anaesthesia (with possibly hazardous 1997). Combinations of these factors are positive-pressure ventilation) seemed suspected to be responsible for increased unfavourable interventions. pulmonary complications in people with The patient consented to a regional diabetes (Morricone et al, 1999). anaesthesia and the authors' team undertook the block described previously. Again, beside With the use of peripheral blocks, the moderate intravenous sedation during the drawbacks of general anaesthesia are not only blocking procedure with midazolame and omitted, but additional benefits added: sufentanil (1 mg and 0.01 mg, respectively) l By contrast to signal transduction under no additional systemic medication was general anaesthesia, blocking a peripheral required. Surgery was uneventful, heart-rate nerve means that afferent signals are ranged between 75 and 85 beats/min; blood stopped before they cause efferent pressure was stable at 130/80 mmHg. endocrine stress responses (Kehlet, 1998). Following the amputation, the patient was l Patients do not require postoperative transferred to his normal ward. fasting, so that continued oral medication At 1-year follow-up the patient was doing and nutrition may help in preserving blood well, with no major documented events. glucose homeostasis during this vulnerable period (McCavert et al, 2010). Discussion The authors' experience indicates that people Conclusion with diabetes may benefit from peripheral Healthcare professionals who are involved nerve blocks for surgical procedures of in surgical procedures of the lower limbs the lower leg. The authors' experience in

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