Neuromuscular electrical stimulation reduces sludge in the popliteal vein.

BACKGROUND: The common peroneal nerve stimulator (CPNS) is a UK-approved device for reducing venous thromboembolism (VTE) risk. It resembles a wrist watch and is placed over the common peroneal nerve, discharging electricity at a rate of 1 impulse/s. It has been presumed that as blood flow slows, erythrocytes aggregate into ultrasound-detectable echogenic particles, described as venous sludge. The aim of the study was to determine whether the CPNS reduces venous sludge by using an ultrasound-derived gray-scale (0-255) venous sludge index (VSI). METHODS: Twenty-five healthy volunteers had their right popliteal vein video recorded using B-mode ultrasound at 22 frames/s in longitudinal and transverse views, standing and lying. This was performed first with the CPNS off and then with the CPNS on. The CPNS impulse intensity used was set from 1 to 7 for each individual, and the level was sufficient to cause an outward jerking movement of the foot. A single frame of the possible 154 frames, lasting 7 seconds, was selected using a random number generator for the image analysis. The "brightness" of the erythrocyte aggregates (pixels) within a circular sampling area was quantified using the VSI. The brighter the sample, the greater the sludge. RESULTS: Values are expressed as median (interquartile range). On standing with the device off, there was a significantly higher VSI (P < .0005) compared with lying (longitudinal view, 27.7 [18.8-41.4] vs 11.7 [5.5-17.5]; transverse view, 20.7 [13.6-32.2] vs 11.4 [6.3-15.9]). Activation of the CPNS significantly reduced all the VSI values (P < .0005) shown (longitudinal view, 2 [1.1-3.2] and 1.5 [0.5-3.1]; transverse view, 1.1 [0.6-2.7] and 0.8 [0.5-2.1]). CONCLUSIONS: The CPNS device significantly reduces venous sludge within the popliteal vein irrespective of whether the subject is standing or lying down or of the longitudinal or transverse position of the ultrasound transducer. The principal mode of action of the device in the claim that it may reduce venous thromboembolism risk may be through a reduction of venous sludge. However, the relationship between erythrocyte aggregation, venous stasis, and venous thromboembolism risk requires more investigation.

Continuous peripheral nerve blockade as postoperative analgesia for open treatment of calcaneal fractures.

OBJECTIVE: To examine the cost and efficacy of methods of general and regional anesthetic for postoperative pain control after open repair of intra-articular calcaneal fractures. We compared single-injection popliteal fossa blocks and continuous infusion popliteal fossa blocks with drug delivered through a catheter from an infusion pump (CPNB) to general or spinal anesthetic alone in terms of hospital charges, length of hospital stay, and postoperative oral and intravenous narcotic use, antiemetic use, and safety. DESIGN: Retrospective review. SETTING: University Level I regional trauma center and associated orthopaedic surgery center. PATIENTS/PARTICIPANTS: Charts were reviewed for all patients undergoing open treatment of calcaneal fractures during a 9-year period. One hundred six of 203 met study inclusion criteria. INTERVENTION: All patients received either general or spinal anesthetic. Patients additionally received preoperative single-injection popliteal fossa blocks, CPNB, or no regional block. OUTCOME MEASUREMENTS: Data were compared from each group for total hospital cost, length of stay, operating room times, narcotic use, postoperative nausea, and hospital readmission. Eighteen patients from the CPNB group who were discharged within 24 hours of surgery were examined in a subgroup analysis of ambulatory treatment. RESULTS: There were no significant differences between the control group and the two regional anesthesia groups in total hospital cost, length of stay, narcotic use, or antiemetic use. However, subgroup analysis demonstrated that ambulatory CPNB patients had significantly lower total hospital costs and narcotic use compared with the remaining CPNB patients. There were no block-related complications. None of the short-stay patients required urgent medical attention or readmission after discharge. CONCLUSIONS: CPNB through an infusion pump may allow patients undergoing open treatment of calcaneal fractures to be safely discharged within 24 hours with a concomitant decrease in healthcare costs. These data suggest that this method of postoperative pain management might be applied to other patients with major foot and ankle trauma and/or reconstructive procedures and that wider use of continuous peripheral nerve blocks may lead to a reduction in healthcare costs.

Continuous epidural block versus continuous popliteal nerve block for postoperative pain relief after major podiatric surgery in children: a prospective, comparative randomized study.

Foot and ankle surgery in children is very painful postoperatively. Adverse effects from opioids and continuous epidural block (CEB) limit their use in children. Continuous popliteal nerve blocks (CPNB) have not been studied for this indication in children. In this prospective, randomized study we evaluated the effectiveness and adverse events of CPNB or CEB in children after podiatric surgery. Fifty-two children scheduled for foot surgery were separated into four groups by age and analgesia technique. After general anesthesia, 0.5 to 1 mL/kg of an equal-volume mixture of 0.25% bupivacaine and 1% lidocaine with 1:200000 epinephrine was injected via epidural or popliteal catheters. In the postoperative period, 0.1 mL x kg(-1) x h(-1) (group CPNB) or 0.2 mL x kg(-1) x h(-1) (group CEB) of 0.2% ropivacaine was administered for 48 h. Niflumic acid was routinely used. Adverse events were noted in each treatment group. Postoperative pain during motion was evaluated at 1, 6, 12, 18, 24, 36, and 48 h. Requirement for rescue analgesia (first-line propacetamol 30 mg/kg 4 times daily or second-line 0.2 mg/kg IV nalbuphine), and motor blockade were recorded. Parental satisfaction was noted at 48 h. Twenty-seven patients were included in the CEB groups and 25 in CPNB groups. There were 32 children 1 to 6 yr of age (CPNB = 15; CEB = 17) and 20 children 7 to 12 yr of age (CPNB = 10; CEB = 10). The demographic data were comparable among groups. Postoperative analgesia was excellent for the two continuous block techniques and in the two age groups. Motor block intensity was equal between techniques. Adverse events (postoperative nausea or vomiting, urinary retention, and premature discontinuation of local anesthetic infusion in the 1- to 6-yr-old group) were significantly more frequent in the CEB group (P < 0.05). Eighty-six percent of the parents in the CEB groups and 100% in the CPNB groups were satisfied. We conclude that although both CEB and CPNB resulted in excellent postoperative analgesia in this study, CPNB was associated with less urinary retention and nausea and vomiting. Therefore, we recommend CPNB as the ideal form of postoperative analgesia after major podiatric surgery in 1- to 12-yr-old children.

Ultrasound observation of the sciatic nerve and its branches at the popliteal fossa: always visible, never seen.

BACKGROUND: In studying patients with sciatic nerve (SN) varices the author found that the sciatic nerve and its major divisions, the tibial and peroneal nerves, could be readily identified on ultrasound imaging of the popliteal fossa. The sciatic nerve lies in the space between the popliteal vein and the small saphenous vein. OBJECTIVES: To confirm that the sciatic nerve can be identified on ultrasonography in patients with venous disease as well as in normal subjects. METHOD: Thirty unselected patients (60 limbs) attending for outpatient consultations were investigated by duplex ultrasound examination of the popliteal fossa. In 10 subjects varicose veins were present, in 20 no varices were visible on clinical examination. RESULTS: The sciatic nerve and its branches where visible and easily recognised in all cases. The sciatic nerve and the small saphenous vein lay in close proximity in cases with of small saphenous vein incompetence. CONCLUSIONS: Ultrasound identification of the sciatic nerve in the popliteal fossa allows assessment of its relationship with the adjacent veins. This technique may be useful in identifying the location of the nerve prior to surgical intervention for varices in the popliteal fossa as well as for endo-luminal occlusion procedures given the close proximity of the vein to the nerve. Sciatic nerve varices, tumours, extrinsic dislocation and nerve lesions may also be detected.