The Use of Hypotensive Technique in Conjunction with Brachial Plexus Block Anesthesia for Surgery of the Upper Extremity

The patient is a 70-yr-old man (95 kg, 170 cm) who had a pathologic fracture to his left humerus. His medical history was notable for renal stones, benign prostatic hypertrophy, and gout, all of which were well- controlled. His only medication was allopurinol. His physical exam was remarkable for decreased range of motion of the left arm, due to pain. He had normal motor and sensory function of left wrist flexors and extensors. The radiographic films of the left humerus revealed a pathologic fracture of the shaft with a 2-cm, round, lytic lesion in the proximal humeral diaphysis (fig. 1). A bone scan revealed uptake in the region of the pathologic fracture, as well as symmetric uptake at the acromioclavicular and sacroiliac joints thought to be consistent with degenerative arthritis. All preoperative blood work was normal except for lactate dehydrogenase level of 561 U/l. His preoperative blood pressure was 150/80 mmHg, with a heart rate of 70 beats/min.

An interscalene block was performed before the administration of sedation by seeking a shoulder paresthesia with a 23-gauge needle. A mixture of 30 ml mepivacaine (1.5%), 20 ml bupivacaine (0.75%), and 200 μg epinephrine was injected in divided doses. Within 2 min, the pain in the arm resolved and the patient was sedated and put in the lateral decubitus position. Inflatable Shoulder-Floats (Trimline Medical Products, Branchburg, NJ) were placed beneath the chest wall and head to decompress the dependent shoulder and keep the neck aligned. Lateral stability was maintained with a bean bag. The patient was sedated with a mixture of intravenous fentanyl (100 μg/h) and propofol (200 mg/h). A 20-gauge catheter was then inserted into the dependent radial artery. Hypotension was induced with 20 mg hydralazine. Mean arterial pressure decreased from 90 mmHg to approximately 55 mmHg. Thirty minutes later, 2 mg metoprolol was given intravenously in divided doses, which reduced the heart rate from 80 to 70 beats/min. Mean arterial pressure and heart rate remained stable thereafter. Sao²was 97–98% throughout surgery, with the patient receiving nasal oxygen at 3 l/min.

An approximately 17-cm-long incision was made posteriorly from the triceps insertion continuing proximally. The radial nerve was dissected out and visualized. The pathologic fracture site was identified and a frozen section revealed a plasmacytoma. The fracture was fixed with a plate and screws. Bone cement mixed with tobramycin was then placed into the bone defect for additional stability, followed by copious irrigation and closure. Intraoperative blood loss was estimated to be 400 ml and 1,500 ml lactated Ringer’s intravenous fluid was administered.

The patient’s course that evening in the postanesthesia care unit was uneventful, and he was soon transferred to the floor with an intravenous morphine patient-controlled analgesia. On postoperative assessment later that evening, he was found to be comfortable, with some residual decreased sensation in the hand as well as weakness of his wrist extensors. On postoperative day 1, the patient had complete return of sensory and motor function. He received a total dose of 30 mg intravenous morphine via patient-controlled analgesia, which was initiated 4.5 hours after surgery. Approximately 30 h after starting his intravenous morphine patient-controlled analgesia, he was converted to oral analgesics. His preoperative hemoglobin was 15.8 mg/dl, and 13.1 mg/dl the next day. He did not require any transfusion of blood products. He was discharged after an uneventful hospital course on postoperative day 4.

Conventional anesthetic approaches in this case would include brachial plexus block with normotension or general anesthesia with either normotension or induced hypotension. As a tourniquet was likely to encroach upon the surgical field, it was decided that intraoperative hypotension would be a better alternative to reduce the possibility of significant blood loss during surgery. Induced hypotension for upper extremity surgery is typically performed with general anesthesia. 3One of the appeals of a brachial plexus block is that it is easier to control pain immediately after surgery. By inducing intraoperative hypotension with a brachial plexus block, we were able to achieve the benefits of control of bleeding during surgery with effective pain control immediately after surgery.

Hypotension was readily induced by using hydralazine with only a slight compensatory tachycardia. Heart rate was maintained throughout surgery at approximately 70 beats/min and mean arterial pressure 55 mmHg after the administration of apresoline and metropolol. Thereafter, stability was maintained with little intervention other than intravenous sedation with propofol and crystalloid administration. This may have been partly because of effective sedation and optimal patient positioning, as well as an intense brachial plexus blockade. In addition, an interscalene block may partially block the cardiac accelerator nerve to the sinus node, 4minimizing the tendency to reflex tachycardia with hypotension.

Induced hypotension in elderly patients with vascular comorbidities during general anesthesia remains controversial. 3By contrast, induced hypotension (mean arterial pressure 45–55 mmHg) with extensive epidural blockade in the elderly and in patients with hypertension or atherosclerotic heart disease appears to be safe when properly administered. 5–7On the other hand, a well- conducted general anesthetic with induced hypotension in elderly high-risk patients lying flat may be equally safe, although this is yet to be documented in large series of patients.

This patient recovered well from the surgery, requiring no blood transfusion and moderate doses of narcotic postoperatively. Induced hypotension in combination with brachial plexus block may be a useful approach in selected cases such as this.