New trends in regional anesthesia for shoulder surgery: Avoiding devastating complications

Surgeons and patients are often reluctant to support regional anesthesia (RA) for shoulder and other orthopedic surgeries. This is because of the sometimes true but usually incorrectly perceived "slowing down" of operating room turnover time and the perceived potential for added morbidity. Recently, severe devastating and permanent nerve injury complications have surfaced, and this article attempts to clarify the modern place of RA for shoulder surgery and the prevention of these complications. A philosophical approach to anesthesiology and regional anesthesiology is offered, while a fresh appreciation for the well-described and often forgotten microanatomy of the brachial plexus is revisited to explain and avoid some of the devastating complications of RA for shoulder surgery.

Dysphagia following anterior cervical arthrodesis is associated with continuous, strong retraction of the esophagus

BACKGROUND

The prevalence of dysphagia after anterior cervical decompression and arthrodesis is estimated to be 50% within one month and 21% at twelve months. However, its exact etiology is not well understood. The objective of the present study was to explore the relationship between intraoperative intra-esophageal pressure due to surgical retraction, esophageal mucosal blood flow at the level of surgery, and postoperative dysphagia. Our hypothesis was that sustained elevated pressure on the esophagus during anterior cervical arthrodesis is associated with postoperative dysphagia.

METHODS

Seventeen selected patients scheduled for anterior cervical arthrodesis were studied. Throughout the procedure, intraluminal pressure in the upper esophageal sphincter was measured (mm Hg) with a custom-made manometer probe and mucosal perfusion was measured at the level of surgery with a laser Doppler flowmeter. The type of retraction chosen by the surgeon was noted. Postoperatively, the patients were specifically evaluated for dysphagia on the first postoperative day and at six weeks, three months, and six months postoperatively with use of the M.D. Anderson Dysphagia Inventory.

RESULTS

Four of the eleven patients who had dynamic retraction and five of the six patients who had static retraction during surgery had postoperative dysphagia. In the group of patients with dysphagia, the average M.D. Anderson Dysphagia Inventory score decreased from 93.8 +/- 12.1 preoperatively to 67.7 +/- 11.4 on the first postoperative day (p < 0.001). The patients with dysphagia had a significantly higher average intraluminal pressure (60.8 +/- 54.3 compared with 54.4 +/- 51.8 mm Hg; p < 0.0001) as well as significantly lower average mucosal perfusion (26.1 +/- 18.1 compared with 40.8 +/- 26.2 tissue perfusion units; p < 0.0001) in comparison with the asymptomatic patients.

CONCLUSIONS

Patients with dysphagia following anterior cervical arthrodesis were exposed to higher intraoperative esophageal pressure and decreased esophageal mucosal blood flow during surgical retraction as compared with patients without dysphagia. In this small series, dynamic retraction seemed to be associated with a lower prevalence of postoperative dysphagia.

Epidural spread after continuous cervical paravertebral block: a case report

BACKGROUND AND OBJECTIVE

This report illustrates epidural spread after continuous cervical paravertebral block (CCPVB). By fluoroscopy, it also explains the mechanism of the complication.

CASE REPORT

A healthy 22-year-old male developed bilateral upper-extremity motor weakness immediately after placement of a continuous cervical paravertebral block for postoperative pain control after shoulder stabilization surgery. The tip of the stimulating catheter was demonstrated in the C7 neuroforamen. Contrast injected through the catheter demonstrated epidural spread. The contralateral block resolved after 4 hours and the patient suffered no respiratory embarrassment or other untoward sequelae.

CONCLUSION

Continuous cervical paravertebral block is a relatively new, but generally well-accepted, modality for postoperative pain control after major surgery to the upper limb. Epidural spread is recognized as a complication. In this particular case, medial placement of the catheter was possibly caused by unintentional medial direction of the bevel of the Tuohy needle. Meticulous attention to the direction of the needle bevel and early recognition and management of adverse events are mandatory. The same principles may apply for continuous thoracic, lumbar, and sacral paravertebral blocks.

A Method to Estimate the Depth of the Sciatic Nerve During Subgluteal Block by Using Thigh Diameter as a Guide

BACKGROUND AND OBJECTIVE

The subgluteal approach is common for sciatic nerve block. Although the surface landmarks are clear, the depth of this nerve at this level is difficult to judge. The purpose of this study is to establish a method of estimating the sciatic nerve depth using the anteroposterior (AP) diameter of the thigh as a marker.

METHODS

The study was undertaken in 2 phases. Phase 1 entailed review of 100 magnetic resonance images (MRIs) of the pelvis and proximal lower extremity of patients. Measurements were taken of the AP diameter of the thigh at the midpoint of the lesser trochanter and then compared with distances of the sciatic nerves from the skin of the posterior aspect of the thigh at the same level. Phase 2 involved enrolling 40 patients undergoing lower-extremity surgery for whom subgluteal sciatic nerve blocks were indicated. The AP diameters of the thighs were measured from the subgluteal groove to the inguinal groove with the patient in the supine position. Placing the patient in the lateral position, the subgluteal sciatic block was then performed by using a stimulating needle. The distances from the skin at which the sciatic nerves were actually found, as estimated by maximum motor response to stimulus, were noted.

RESULTS

Phase 1 showed a mean AP diameter of 18.94 cm +/- 2.61 cm (mean +/- standard deviation [SD]), mean nerve depth of 6.51 cm +/- 1.46 cm (mean +/- SD), and a linear regression slope of 0.48. Phase 2 showed a mean AP diameter of 16.28 cm +/- 2.73 cm (mean +/- SD), a mean nerve depth of 6.99 cm +/- 1.39 cm (mean +/- SD), and a linear regression slope of 0.43. The thigh diameters differed (P < .001) between the groups, but there was no difference in the depth to the sciatic nerve between the 2 groups (P = .07).

CONCLUSIONS

Comparing phase 1 and phase 2 datasets shows the slopes of linear regression lines are nearly parallel. The clinical data from phase 2 verify the anatomical data collected in phase 1 and show that the sciatic nerve depth to AP diameter ratio is 0.43 or the depth of the sciatic nerve is approximately 43% of thigh diameter if the patient is positioned in the lateral decubitus position.

Electrical nerve stimulation using a stimulating catheter: what is the lower limit?

OBJECTIVES

To minimize the risk of intraneural injection when performing nerve blocks, some authors caution against injecting through a needle placed with motor responses observed at nerve stimulator output settings of 0.3 mA or less. We present a case of placing a continuous cervical paravertebral catheter with brisk motor response while stimulating the catheter at 0.05 mA, with no adverse sequelae.

CASE REPORT

A 56-year-old man scheduled for rotator cuff repair received a continuous cervical paravertebral block for intraoperative and postoperative pain control. A stimulating catheter was used for the block. During catheter placement, nerve stimulator output was decreased to 0.05 mA at 300 micros and the motor response remained brisk. The patient was not significantly sedated and experienced no pain during placement or with injection of 40 mL of 0.5% ropivacaine through the catheter. Narcotic drugs were not required during surgery, and the block provided excellent postoperative pain control. Catheter position was evaluated by fluoroscopy to further identify the catheter's relationship to the brachial plexus. The nerve trunks of C5 and C6 were clearly visible after 1 mL of iohexol (Omnipaque) was injected through the catheter. The catheter was removed the following day. At the follow-up visit 2 weeks later, the patient's neurological examination remained unremarkable.

CONCLUSION

We present a single case of successful placement of a stimulating catheter with no neurological injury even when motor response occurred at very low nerve stimulator output settings.

At the cords, the pinkie towards: Interpreting infraclavicular motor responses to neurostimulation

Identification of elicited muscle twitches while performing infraclavicular block of the brachial plexus is often confusing but is critical for success of the block. An easily defined endpoint when evaluating these motor responses to neurostimulation is essential, as it is necessary to block the appropriate cord or cords. In addition to an extensive review of the motor and sensory neuroanatomy of the upper extremity, we describe an easy method to learn and remember the motor response to stimulation of each of the cords of the brachial plexus. If the arm is positioned in the anatomical position, the 5th digit (pinkie) moves laterally (pronation of the forearm) when the lateral cord is stimulated, posteriorly (extension) when the posterior cord is stimulated, and medially (flexion) when the medial cord is stimulated. The pinkie thus moves "toward" the cord that is stimulated.

Early experience with continuous cervical paravertebral block using a stimulating catheter

BACKGROUND AND OBJECTIVES

This study reports our early experience with continuous cervical paravertebral block (CCPVB) using a stimulating catheter for the management of acute pain after shoulder surgery.

METHODS

This prospective observational study presents 256 CCPVB for pain relief after 14 different shoulder operations. Surgery was performed under general anesthesia and blocks were placed prior to induction of general anesthesia (n = 81 [32%]), after induction of general anesthesia (n = 116 [45%]), or postoperatively in the recovery room (n = 59 [23%]). A bolus dose of 30 mL of 0.5% ropivacaine was followed by an infusion of 0.1 mL/kg/h of 0.2% ropivacaine. Patient- or nurse-initiated bolus doses of 10 mL of the same drug were used for breakthrough pain and rescue analgesics were available. Postoperative pain, patient satisfaction, and motor function in different parts of the upper limb were evaluated immediately after surgery (time 0), and then 6, 12, 24, 48, 60 hours, and 14 days postoperatively.

RESULTS

An average of 2 (range 1-7) attempts were needed to advance the catheter while still stimulating the nerve. Average postoperative pain ranged from 0.27 +/- 1.04 cm to 0.78 +/- 1.56 cm (mean +/- SD) on a visual analog scale (VAS) (0-10 cm) for the first 48 hours and 3.8 +/- 2.1 cm and 3.5 +/- 2.4 cm at 60 hours and 14 days, respectively. Patient satisfaction on a VAS of 0 to 5 was 4.19 +/- 1.1, 4.28 +/- 1.01, and 4.69 +/- 1.05 at times 0, 6 hours, and 14 days, respectively. Motor function returned to normal in the fingers within 24 hours and in the shoulder within 60 hours. Complications included Horner's syndrome (40%), dyspnea (8%), superficial skin infection (5%), posterior neck pain (22%), subclavian artery puncture (1%), contralateral epidural spread (4%), and 8% of the patients complained of an unpleasant "dead feeling" of the arm. Ninety-one percent of patients would request CCPVB again for future shoulder surgery. There was no evidence of nerve damage.

An indication for continuous cervical paravertebral block (posterior approach to the interscalene space)

We present a patient who required perioperative analgesia with continuous nerve block for shoulder disarticulation, for whom the only approach possible to the brachial plexus was from posterior. A 51-yr-old woman was suffering from intractable upper extremity pain and dysfunction as a result of severe lymphedema after metastatic spread of breast cancer to the axilla. Her pain was poorly controlled despite aggressive treatment with oral, systemic, and intrathecal opiates. She presented for amputation of her arm as a last resort for management of pain. In order to provide optimal postoperative analgesia, continuous peripheral nerve block was selected in consultation with the patient, and due to anatomic disfigurement and tumor invasion, a continuous cervical paravertebral block was placed preoperatively and shoulder disarticulation was performed using a combined regional/general anesthesia technique. The patient had an uneventful recovery without pain for the 6 postoperative days that the catheter was in place and 0.25% bupivacaine was infused at 5 mL/h. Because of anatomic considerations, which precluded the use of all other approaches to the brachial plexus, the posterior cervical paravertebral approach provided an effective means of pain control in this difficult clinical situation.

Surface mapping of peripheral nerves in children with a nerve stimulator

Defining anatomical landmarks may be difficult in the growing child. With the aid of a peripheral nerve stimulator, the path of many superficial peripheral nerves can be 'mapped' prior to skin penetration by stimulating the motor component of the peripheral nerve percutaneously with a 2-3.5 mA output. The required current will vary and is dependent upon the depth of the nerve and the moistness of the overlying skin. This 'nerve mapping technique' has proved particularly useful for brachial plexus, axillary, ulna and median nerve blocks in the upper limb and femoral and popliteal nerve blocks in the lower limb. It is a useful teaching tool and improves the success rate of peripheral nerve blocks in children of all ages.

Continuous interscalene block for ambulatory shoulder surgery

Management of acute post-operative pain due to shoulder surgery may be successfully and consistently achieved in ambulatory patients by using continuous interscalene block. This chapter outlines the anterior and posterior approaches to the proximal brachial plexus and describes a method of precisely placing a catheter along the brachial plexus by stimulating the plexus through the needle used for placing the catheter as well as through the catheter itself. A technique for securing the catheter by subcutaneous tunneling to prevent dislodgement is also described. Suggested drugs and dosages for initial boluses, continuous infusions and patient controlled interscalene analgesia are discussed. Sedation for block placement, and special precautions, are outlined.

A comparison of propofol and remifentanil for sedation and limitation of movement during periretrobulbar block

STUDY OBJECTIVES

To compare clinical conditions in patients sedated with propofol or remifentanil during combined peri-bulbar and retrobulbar block (PRBB) for cataract surgery.

DESIGN

Prospective, randomized, double-blind study.

SETTING

Private clinic.

PATIENTS

106 ASA physical status I and II patients scheduled for cataract surgery.

INTERVENTIONS

Patients were randomized to receive either 0.5 mg/kg propofol (Group P) or 0.3 microg/kg remifentanil (Group R) as an intravenous (IV) bolus 1 minute prior to PRBB. At the same time, patients in both groups also received 0.5 to 1 mg midazolam IV. Movement of the hands, arms, head, and eyes were counted during each stage of the procedure by an observer who was blinded to the sedation used. Heart rate (HR), blood pressure (BP), respiratory rate (RR), expiratory CO(2) (PECO(2)), and hemoglobin oxygen saturation (SaO(2)) were recorded every minute for 10 minutes after the PRBB. Anesthetic complications, recall, and the pain experienced with the block and surgery were compared between the two groups. Means and variance of the results were compared with one-way analysis of variance and Fisher's exact test.

MEASUREMENTS AND MAIN RESULTS

Movements of the hands, arms, and head were significantly greater in Group P during all stages of the block. Almost no movements were recorded in the remifentanil group. Immediately after the PRBB (1 to 6 min), HRs were higher in Group P (73 +/- 11 bpm vs. 67 +/- 10 bpm; p = 0.0075), whereas the RRs were slower in Group R for the period 1 to 5 minutes after the PRBB (16 +/- 5 breaths/min vs.14 +/- 4 breaths/min; p = 0.0206). At these times, the mean PECO(2) was higher in Group R (36 +/- 7 mmHgvs. 32 +/- 9 mmHg; p = 0.0125). Nineteen patients in the propofol group sneezed during the medial peribulbar injection compared with none in the remifentanil group. Anesthetic and surgical complications were unremarkable and similar for the two groups.

CONCLUSIONS

Respiratory depression with remifentanil was mild and not clinically significant. Remifentanil sedation for this application was superior to sedation with propofol.