Consensus of the Orthopedic Anesthesia, Pain, and Rehabilitation Society on the use of peripheral nerve blocks in patients receiving thromboprophylaxis.

Evidence supports the concept that patients undergoing major orthopedic surgery benefit from either thromboprophylaxis or peripheral nerve blocks, especially continuous techniques. A group of anesthesiologists with significant experience in orthopedic anesthesia and peripheral nerve blocks reviewed the literature related to thromboprophylaxis and peripheral nerve blocks and their combination in orthopedics. Major bleeding, including retroperitoneal hematoma, is an established complication of thromboprophylaxis. Major bleeding, including retroperitoneal hematoma, is also an established complication of peripheral nerve blocks. Between 1997 and 2012, only 4 case reports of major bleeding were reported in patients receiving thromboprophylaxis and peripheral nerve blocks. Evidence supports the safety of the combination of thromboprophylaxis and peripheral nerve blocks. This group of experts concluded that currently there is no evidence that the combination of thromboprophylaxis and peripheral nerve block increases the risk of major bleeding compared to either of the treatments alone.

Intraoperative femoral nerve stimulation in evaluation of patellar tracking: tourniquet effects and catheter placement.

BACKGROUND: Dynamic intraoperative assessment of patella tracking utilizes femoral nerve stimulation to contract the quadriceps muscles in assessing the proper distance to transfer the tibial tubercle during distal realignment procedures for patellofemoral instability. PURPOSE: We describe the effects of tourniquet inflation and catheter placement on intraoperative femoral nerve stimulation for assessment of patellar tracking. METHODS: Percutaneous electromyographic (EMG) needles were placed into the quadriceps and sartorius muscles to monitor muscle activity and changes in amplitude threshold (mA) required for femoral nerve stimulation with increasing tourniquet inflation times. Eleven patients used ultrasound for catheter placement and ten were manually placed based upon body landmarks. RESULTS: Tourniquet application time correlated positively with the change in amplitude threshold required to generate muscle contraction. Patients had an average four-fold increase in required stimulus amplitude from the baseline thresholds (pre-tourniquet inflation) to final thresholds (tourniquet inflated) with a two-hour tourniquet inflation time. The use of ultrasound for catheter placement significantly decreased the baseline amplitude required in comparison with catheters placed without ultrasound, (p = 0.0330). CONCLUSIONS: Increased tourniquet inflation times require greater stimulus amplitude to generate quadriceps muscle contraction. Ultrasound guidance for catheter placement can provide femoral nerve stimulation at low amplitudes.

Ultrasound-guided approach for axillary brachial plexus, femoral nerve, and sciatic nerve blocks in dogs.

OBJECTIVE: To describe an ultrasound-guided technique and the anatomical basis for three clinically useful nerve blocks in dogs. STUDY DESIGN: Prospective experimental trial. ANIMALS: Four hound-cross dogs aged 2 +/- 0 years (mean +/- SD) weighing 30 +/- 5 kg and four Beagles aged 2 +/- 0 years and weighing 8.5 +/- 0.5 kg. METHODS: Axillary brachial plexus, femoral, and sciatic combined ultrasound/electrolocation-guided nerve blocks were performed sequentially and bilaterally using a lidocaine solution mixed with methylene blue. Sciatic nerve blocks were not performed in the hounds. After the blocks, the dogs were euthanatized and each relevant site dissected. RESULTS: Axillary brachial plexus block Landmark blood vessels and the roots of the brachial plexus were identified by ultrasound in all eight dogs. Anatomical examination confirmed the relationship between the four ventral nerve roots (C6, C7, C8, and T1) and the axillary vessels. Three roots (C7, C8, and T1) were adequately stained bilaterally in all dogs. Femoral nerve block Landmark blood vessels (femoral artery and femoral vein), the femoral and saphenous nerves and the medial portion of the rectus femoris muscle were identified by ultrasound in all dogs. Anatomical examination confirmed the relationship between the femoral vessels, femoral nerve, and the rectus femoris muscle. The femoral nerves were adequately stained bilaterally in all dogs. Sciatic nerve block. Ultrasound landmarks (semimembranosus muscle, the fascia of the biceps femoris muscle and the sciatic nerve) could be identified in all of the dogs. In the four Beagles, anatomical examination confirmed the relationship between the biceps femoris muscle, the semimembranosus muscle, and the sciatic nerve. In the Beagles, all but one of the sciatic nerves were stained adequately. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasound-guided needle insertion is an accurate method for depositing local anesthetic for axillary brachial plexus, femoral, and sciatic nerve blocks.

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.