Long current impulses may be required for nerve stimulation in patients with ischemic pain

Purpose

To report on the efficacy of peripheral plexus catheters in the treatment of ischemic pain in spite of nerve stimulation with long current impulses.

Clinical features

Tw o patients with severe neuropathic ischemic foot pain are described. A 56-yr-old man with diabetes, renal failure, and autonomic neuropathy presented with severe ischemic foot pain. Opioids produced excess sedation and hypotension. A 62-yr-old woman was admitted after femoralpopliteal bypass and developed a reperfusion pain syndrome not relieved with opioids, gabapentin, amitryptiline, and clonidine. In both patients, a sciatic plexus catheter was placed with resolution of pain. Conventional nerve stimulation, which uses a pulse duration of 0.1 msec, did not result in muscle contraction. However, by using a nerve stimulator capable of delivering a 1.0 msec impulse duration, a muscle twitch or paresthesia endpoint ensued allowing for successful catheter placement.

Conclusion

Peripheral plexus catheters provide a safe alternative to systemic analgesics for pain relief in patients with ischemic foot pain. However, conventional nerve stimulation techniques may not elicit a motor response in patients with underlying neuropathy, and the use of nerve stimulators capable of delivering long current impulses is recommended.     

瑞芬太尼、芬太尼对过度肥胖患者麻醉效果及麻醉复苏质量的影响

目的 探讨芬太尼和瑞芬太尼对于肥胖患者全身麻醉效果及复苏的影响,探索联合应用两种药物的可行性,并找到较为可行的联合方式.方法 按随机区组设计将实施全身麻醉的肥胖患者分为4组,每组20例,分别是芬太尼组(F组),瑞芬太尼组(R组),芬太尼复合瑞芬太尼l组(RF1组)和芬太尼复合瑞芬太尼2组(RF2组),比较4组患者的全身...     

Clinical effect of mivacurium in morbidly obese patients

OBJECTIVES: To compare the clinical effect of mivacurium in morbidly obese and normal-weight patients. PATIENTS AND METHODS: Ten morbidly obese patients (body mass index >40) and 10 normal-weight patients (body mass index, 21-24) with normal plasma cholinesterase levels. Anesthesia was provided with propofol and remifentanil in continuous infusion and a mixture of oxygen and nitrous oxide. Mivacurium was administered at a dose based on the patient's weight (0.15 mg x kg(-1)). The neuromuscular block was monitored by train-of-four (TOF) acceleromyography after stimulation of the cubital nerve at the forearm. We measured the onset time (time from administration of the muscle relaxant to 95% twitch depression), duration of block (times from dosing to 5% recovery after the first twitch [T1] of a TOF stimulus and to a TOF ratio of 80%), and the recovery indices (time between 25% and 75% recovery after T1 and between recovery of TOF ratios of 25% and 80%). Groups were compared with the Student t test. RESULTS: Mean (SD) onset time was similar in the 2 groups (normal weight 2.73 [1] minutes vs morbidly obese 1.91 [0.6] minutes). Other measures of duration and recovery were also similar in the 2 groups, respectively: duration of dose-T1 5%, 12.23 (2.1) vs 11.45 (3) minutes; dose-TOF ratio 80%, 24.71 (4.6) vs 24.81 (5) minutes); recovery index T1 25%-75%, 6.45 (2) vs 5.56 (1) minutes; recovery of TOF ratio T1 25%-80%, 9 (2) vs 10.11 (2) minutes. CONCLUSION: We found no differences in the clinical effect of mivacurium between morbidly obese and normal-weight patients when doses were based on real weight.     

Pre-operative carbohydrate loading may be used in type 2 diabetes patients

Background: Post-operative insulin resistance and hyperglycaemia are associated with an impaired outcome after surgery. Pre-operative oral carbohydrate loading (CHO) reduces post-operative insulin resistance with a reduced risk of hyperglycaemia during post-operative nutrition. Insulin-resistant diabetic patients have not been given CHO because the effects on pre-operative glycaemia and gastric emptying are unknown.
Methods: Twenty-five patients (45–73 years) with type 2 diabetes [glycated haemoglobin (HbA1c) 6.2 ± 0.2%, mean ± SEM] and 10 healthy control subjects (45–72 years) were studied. A carbohydrate-rich drink (400 ml, 12.5%) was given with paracetamol 1.5 g for determination of gastric emptying.
Results: Peak glucose was higher in diabetic patients than in healthy subjects (13.4 ± 0.5 vs. 7.6 ± 0.5 mM; P <0.01) and occurred later after intake (60 vs. 30 min; P <0.01). Glucose concentrations were back to baseline at 180 vs. 120 min in diabetic patients and healthy subjects, respectively ( P <0.01). At 120 min, 10.9 ± 0.7% and 13.3 ± 1.2% of paracetamol remained in the stomach in diabetic patients and healthy, subjects respectively. Gastric half-emptying time (T50) occurred at 49.8 ± 2.2 min in diabetics and at 58.6 ± 3.7 min in healthy subjects ( P <0.05). Neither peak glucose, glucose at 180 min, gastric T50, nor retention at 120 min differed between insulin (HbA1c 6.8 ± 0.7%)- and non-insulin-treated (HbA1c 5.6 ± 0.4%) patients.
Conclusions: Type 2 diabetic patients showed no signs of delayed gastric emptying, suggesting that a carbohydrate-rich drink may be safely administrated 180 min before anaesthesia without risk of hyperglycaemia or aspiration pre-operatively.     

Nipple piercing may be contraindicated in male patients with chest implants

The authors present a man who underwent chest augmentation and nipple piercing. The patient developed chronic nipple infection, which led to unnecessary invasive diagnostic procedures, serious implant infection, and eventually urgent explantation. This unfavorable scenario illustrates the distinct features of the procedure in men, which includes close proximity of the nipple to the implant and reduced awareness by health care providers. Based on this case the authors recommend avoiding nipple piercing in men with chest implants.     

Bone mineral density may be related to atherosclerosis in hemodialysis patients

Biological interactions between the bone and the blood vessels are gradually being clarified. To investigate the relationship between bone mineral density and atherosclerosis in hemodialysis patients, we examined the bone mineral density and the intima-media thickness of the carotid artery in 83 dialysis patients with non-diabetic nephropathy (44 men and 39 women) aged from 23 to 83 years. The duration of hemodialysis ranged from 2 to 344 months. The bone mineral density of the radius was measured by dual-energy X-ray adsorptiometry, and the ratio of this value to the standard value for the same age and gender was calculated ( Z-score). As an index of atherosclerosis, the intima-media thickness of the carotid artery was measured by high resolution B-mode ultrasonography. Then the relationship between the Z-score and various factors was examined using Spearman's rank correlation analysis and multiple regression analysis. The Z-score showed a negative correlation with the duration of hemodialysis, the carotid intima-media thickness, and the levels of alkaline phosphatase, intact parathyroid hormone, and low-density lipoprotein cholesterol by Spearman's rank correlation analysis. In addition, the Z-score showed a positive correlation with the lipoprotein (a) level and a negative correlation with the duration of hemodialysis, intima-media thickness, intact parathyroid hormone, and low-density lipoprotein cholesterol by multiple regression analysis. These findings suggest that the decrease of bone mineral density in hemodialysis patients is correlated with secondary hyperparathyroidism and hyperlipidemia, which are factors known to promote atherosclerosis, and thus bone density changes might be related to the progression of atherosclerosis, or vice versa.     

Current leakage in hemodialysis machines may be a safety risk for patients

During hemodialysis, the dialysis fluid is conductive and allows current to flow from or to the machine if a difference in electrical potential occurs. This may cause a health risk for the patient. We investigated the presence of such current during various conditions in 17 dialysis machines: the Gambro AK10 (n = 5) and AK100 (n = 3), and the Fresenius 2008C (n = 3), 2008E (n = 2), and 4008E (n = 4). Current leakage measurements were performed without connection of the patient to the system by using a copper tube inserted into the stream of the dialysis fluid at the point where the patient would normally be connected to the dialyzer. The current leakage (measured in microA) at the ground site was significantly higher for the AK10 and the 2008C than for the AK100, 2008E, and 4008E machines. The current leakage, at the site where the dialyzer is located, was highest for the AK10 and less for the AK100, 2008C, 2008E, and 4008E. The 2008C and 2008E dialyzers had the highest maximal current leakage when a malfunctioning external device was attached while the AK100 had less and the AK10 had the least leakage. There was a great variation in leakage current among the dialysis machines. The greatest risk occurred when the patient also was connected to other electric devices with current leakage.     

Duplex scanning may be used selectively in patients with primary varicose veins

Reflux was assessed using hand-held Doppler (HHD) and duplex scanning in 72 patients with primary, previously untreated varicose veins (108 limbs). The aims of the study were (i) to compare the accuracy of HHD assessment with duplex scanning, (ii) to assess the benefit of tourniquet testing and (iii) to identify patients who would benefit from a policy of selective duplex scanning. HHD accurately assesses the saphenofemoral junction (SFJ) and long saphenous vein (LSV) reflux. HHD assessment of the saphenopopliteal junction (SPJ) reflux has a low positive predictive value. A high negative predictive value reflects absent SPJ reflux assessed using HHD accurately. Tourniquet testing is not helpful. Selective duplex scanning of limbs with suspected SPJ reflux, no identifiable site of reflux or posterior thigh perforator reflux on HDD (39% of limbs), would result in the appropriate surgical procedure being performed in 102 (94%) limbs, excessive surgery in 5 (5%) limbs and inadequate surgery in only 1 (1%) limb. The use of selective criteria for duplex scanning would reduce the workload of the vascular laboratory without compromising patient care.