The anesthetic considerations while performing supraclavicular brachial plexus block in emergency surgical patients using a nerve stimulator.

Regional anesthesia is favored in patients who undergo emergency extremity (limb) surgery, and specifically so in the absence of fasting status. In the absence of ultrasonic guidance, the nerve stimulator still remains a valuable tool in performing a brachial block, but its use is difficult in an emergency surgical patient and greater cautious approach is essential. We identified the supraclavicular plexus by the nerve stimulation-motor response technique as follows. Anterior chest muscles contractions, diaphragmatic contraction, deltoid contractions, and posterior shoulder girdle muscle contractions when identified were taken as "negative response" with decreasing stimulating current. A forearm muscle contraction, especially "wrist flexion" and "finger flexion" at 0.5 mA of current was taken as "positive response." If no positive response was identified, the "elbow flexion" was considered as the final positive response for successful drug placement. The series of patients had difficulty for administering both general and regional anesthesia and we considered them as complex scenarios. The risk of the block failure was weighed heavily against the benefits of its success. The described series includes patients who had successful outcomes in the end and the techniques, merits, and risks are highlighted.

INTRODUCTION

Emergency upper extremity surgery in acute trauma setting presents a challenge to anesthesiologists. Preexisting morbid illnesses and absence of fasting status make regional block a safer alternative to general anesthesia (GA). Certain essential principles that need to be followed while performing supraclavicular brachial plexus block using a nerve stimulator were uniformly applied to a series of trauma patients with complex clinical presentations.[123] This series includes patients who had successful outcomes and the techniques, merits, and risks are discussed and highlighted.

CASE REPORT

Table 1 describes patients undergoing emergency surgical repair of traumatized upper limb in different age groups under the American Society of Anesthesiologists classification 1–3 status. All received supraclavicular brachial plexus block using 22 gauge, 2.5 inch VYGON, 30° blunt bevel nerve locator needle. A nerve stimulator (INMED, locator, HN) evoked motor response technique was used to identify the plexus. The responses identified as positive for block accuracy are finger flexion, wrist flexion, anterior forearm twitches, and elbow flexion in that order [Figure 1].

Table 1

Demographic data and summary of “problems” of nerve stimulator technique based supraclavicular regional anesthesia

Figure 1

The “cadre” of response

The mixture of local anesthetic (MOLA) was injected (maximum volume 40 ml) after obtaining the desired response at a current of 0.5 mA. Levobupivacaine 0.25–0.5%, lignocaine 2%, with or without adrenaline 1:200,000, hyaluronidase 1500 IU were used alone or in combination. Opioids, injection fentanyl, midazolam, and oxygen were administered whenever warranted. After 30–40 min, effective brachial block was confirmed by the analgesia component and motor blockade, whenever feasible. Surgery was uneventful in all patients.

Individual case events

Case 1

This patient presented with a full stomach and complete heart block (CHB). Brachial block was performed with low volume (20 ml) of local anesthetic, 0.5% injection levobupivacaine. Transvenous pacing (TVP) equipment and a cardiology support were readied. After the 80 min procedure, severe bradycardia and asystole occurred. Immediate cardiopulmonary resuscitation was performed and the patient was revived. 5 min later, TVP was carried out for a second episode of asystole. Permanent pacemaker was implanted and patient was discharged on day 13.

Case 2

This elderly patient presented with subcutaneous emphysema of the anterior chest wall, neck, and shoulder (fractured 3–6 ribs). An open arm wound needed emergency debridement. Patient's saturation was 93% with oxygen 6 L/min on face mask. Supraclavicular brachial block was performed after eliciting flexor motor responses at wrist. The MOLA (lignocaine 2%, with adrenaline 1:200,000 dilution, 12 ml and 0.5% levobupivacaine, 20 ml) was injected. An intercostal drain (ICD) was placed into the ipsilateral hemithorax.

Case 3

A chronic smoker with fractured cervical spine and cervical collar in-situ needed soft tissue repair of elbow. There was no neurological deficit. Chest auscultation revealed bilateral inspiratory and expiratory rhonchi. Shoulder pad was avoided while performing the block.

Case 4

A young male needed fasciotomy for upper limb compartment syndrome, 2 days following unknown animal species bite [Figure 2a]. Patient had oliguria, metabolic acidosis, and creatinine 3.1 mg/dl. Coagulation profile was normal. Only partially visible muscle twitches of the arm were observed in response to the block, with virtually no visible forearm motor responses in the stiff distal extremity.

Figure 2

(a) Patient's stiff hand offers no motor response for nerve stimulation in severe compartment syndrome. (b) Patient with epidermolysis bullosa of non injured limb. Any pressure can lead to bulla formation. (c) Absent anatomical structure in major amputation of upper limb precludes nerve stimulatory responses

Case 5

A young lady with congenital heart disease, severe mitral stenosis, and atrial fibrillation (valve area 0.6 cm2, heart rate 128/min) underwent emergency brachial artery embolectomy. While already on warfarin, she had received an additional dose of intravenous heparin 5000 IU in the referring hospital. Her INR was 3.4. Brachial block was performed with 30 ml of MOLA. Ultrasound evaluation was done 1 h after surgery to rule out injection site hematoma.

Case 6

A 11-year-old girl was posted for closed K-wiring of displaced radius. She had a known history of recurrent epidermolysis bullosa exacerbations and remissions [Figure 2b-the opposite limb]. Block was performed using MOLA (lignocaine, 2% 4 ml and levobupivacaine 0.5% 16 ml). The surgery and postoperative period were uneventful.

Case 7

A patient of chronic kidney disease (CKD with a closed fracture, ulna and radius, was posted for open reduction and internal fixation. He was a diabetic on insulin and had prior myocardial infarction. His recent echocardiogram revealed left ventricular ejection fraction of 30%. Block was performed using MOLA (without adrenaline) and total volume of 20 ml.

Case 8

A young male with complete below-elbow forearm transection was posted for re-implantation [Figure 2c]. Brachial block was performed on a hemodynamically stable patient. The volume injected was 35 ml. Technically, only the biceps muscle activity could be used for elicitation of motor response. Patient had no reperfusion event and remained hemodynamically stable during and after the procedure (lasting 8 h). No supplementation with GA was required.

Case 9

An adult male had left-sided flail chest with fractures of multiple ribs, right pneumothorax, fracture left humerus, and compound fracture of both bones left fore-arm [Figure 3]. SpO2 maintained around 90–93% on high concentration mask oxygen. His arterial blood gas was on borderline and mechanical ventilation was kept ready. Brachial plexus block with MOLA, volume 30 ml (2% lignocaine with adrenaline −20 ml and 0.25% levobupivacaine −10 ml) was administered for left arm and fore-arm injuries. Bilateral ICDs were inserted. Surgery and postoperative period were uneventful. Thoracic epidural analgesia was considered for pulmonary rehabilitation subsequently.

Figure 3

When phrenic nerve is involved in a patient with flail chest, respiratory distress can be worse. Chest injury is common with shoulder or arm injury

No patient required mechanical ventilation. There was no mortality in the subsequent postoperative period.

DISCUSSION

The patients presented here were high-risk candidates for both GA and regional anesthesia. Endotracheal GA was intentionally avoided for many reasons including absence of fasting status in many. Intermittent positive pressure ventilation (IPPV) can worsen preexisting subcutaneous emphysema (case 2). Patients with CKD and cardiac illness can have delayed recovery and higher morbidity; and therefore in patients with CKD, compartment syndrome (case 4 and 7), and mitral valvular disease (case 5), GA was consciously avoided. Cervical fracture can worsen with displacement of segments after laryngoscopy and endotracheal insertion during GA (case 3). Epidermolysis bullosa simplex (case 6) causes blisters in skin and mucus membrane especially of the airway, hands, and feet. Airway involvement results in significant morbidity.[4] Though GA with IPPV helps flail chest patients (case 9), postoperative, continued mechanical ventilation could become a necessity and this may contribute to additional morbidity. Since our patient had borderline lung functions, he did not require mechanical ventilation and this could be partly attributed to the benefit accorded by thoracic epidural analgesia.

The aim of nerve stimulation was to achieve higher accuracy with intentional reduction in dose and total volume of injectable local anesthetic and thus indirectly reduce the plasma levels. Despite reductions in levobupivacaine dose and volume, adverse effects on conduction system appeared in our CHB patient. However, immediate placing of TVP resulted in a successful outcome. The delayed cardiac arrest possibly can be explained with Tmax of levobupivacaine effects and in animals, conduction delays were still observed with levobupivacaine.[5] Dose reductions were for different reasons altogether in the patient with CKD and poor cardiac condition (case 7). Patients with CKD on repeated dialysis may present in either a volume depleted or volume loaded state. Use of brachial anesthesia may worsen the existing respiratory condition in an asymptomatic patient owing to local anesthetic induced myocardial depression and the associated, unintended phrenic nerve palsy. Contrast this with our patient with compartment syndrome and marked renal dysfunction (case 4) in whom dose reduction was not considered. Renal failure does not impose dose reductions for local anesthetic use.[6]

Ipsilateral chest injuries are commonly associated with arm and elbow injuries following road traffic accident. An incidence of phrenic palsy up to 60% with supraclavicular blocks has been reported.[7] Though unilateral phrenic nerve palsy is not associated with clinically significant effects in normal individuals, preexisting pulmonary pathology can aggravate the dysfunction.[8] However, use of compression proximally may not prevent spread of local anesthetic to the phrenic nerve inducing a respiratory palsy. None of our chest injury and cervical spine injury patients ended up in respiratory distress; however, it is uncertain whether the phrenic nerve was spared during the block.

Patients with peripheral thromboembolic events necessitating emergency surgery for limb salvage will most often be receiving anticoagulants. No specific anesthetic guidelines are available for the management in such situations.[9] The use of peripheral nerve blocks in cardiac patients, who are on anticoagulation therapy is also controversial.[9] Additional anticoagulation with heparin should be delayed at least for 1 h after performing the block. Patients may be monitored closely to detect hematoma postoperatively with an ultrasound.[10]

The common disadvantages of nerve stimulator techniques in emergency trauma patients include difficulty in positioning of limb, pain while stimulating muscle contraction, interference with visualization of motor responses owing to applied heavy dressings and slab, bleeding open wounds, etc. A vascular injury patient may be shifted to the operation theater with inflated tourniquet in-situ. A preexisting nerve injury will preempt the use of nerve stimulator. Unknown coagulation status of patient and association of other injuries which do not entail surgical intervention may further complicate the issue. In our series, patient with compartment syndrome and forearm amputation had technical restriction in elicitation of distinct motor responses. In the absence of finger, wrist or elbow flexion, the next cadre level response should be elicited. Other associated problems in major limb reimplantations include excessive blood loss and hemodynamic instability, reperfusion events, protracted surgery, etc., and all these may present hurdles when regional anesthesia is used alone.[11] An often applied shoulder extension pad cannot be used in trauma patients with cervical spine fracture. Hindered nerve stimulation in an improperly positioned patient enhances the probability of arterial puncture, phrenic palsy, and inadequate motor response elicitation.

CONCLUSION

Our series highlights the technical and pharmacological complexities when nerve stimulator based supraclavicular blocks are deployed in emergency anesthesia for upper limb surgery. The anatomical and functional concerns, necessity for dose and volume reduction of injectable, and the need for higher accuracy should be considered. One needs to successfully overcome issues like cardiac conduction abnormalities, associated chest and cervical spine injuries, anticoagulation, pulmonary edema, compartment syndrome, and reperfusion events prior to, during, and after the block procedure. The “cadre” response based nerve stimulator guided supraclavicular brachial plexus block can be employed for successful outcome.