Heart rate variability may identify patients who will develop severe bradycardia during spinal anaesthesia.

BACKGROUND AND OBJECTIVES: The reported incidence of cardiac arrest during spinal anaesthesia is 6.4+1.2 per 10,000 patients. Many of these arrests occurred in healthy young patients during minor surgery. This raises the question of whether some of them were avoidable. We investigated the value of Heart Rate Variability (HRV) to identify patients prone to developing severe bradycardia during spinal anaesthesia. METHODS: Eighty ASA I-II patients, 21-60 years of age, undergoing elective surgery under spinal anaesthesia were studied. The HRV was assessed for 25 min before the spinal block. Two spectral components of HRV were calculated: a low-frequency (LF) and a high-frequency (HF) component. Patients were grouped according to whether bradycardia did or did not develop during spinal anaesthesia. RESULTS: Nineteen patients developed severe bradycardia (<45 b.p.m.). The mean value of HF before spinal anaesthesia was significantly increased in the bradycardic group (P<0.05). The correlation between baseline heart rate (HR(baseline)) and minimum heart rate and LF, HF during spinal anaesthesia was significant (P<0.01). A receiver operator curve characteristic analysis showed a sensitivity and specificity of HF and HR(baseline) of 65% and 74%, respectively, to predict bradycardia <45 b.p.m. after spinal anaesthesia. CONCLUSIONS: The present study shows that HF and clinical factors such as patient's HR(baseline) could identify patients prone to developing severe bradycardia during spinal anaesthesia.

Rhabdomyolysis following laparoscopic gastric bypass.

Rhabdomyolysis is a rare complication of serious surgical procedures, and constitutes a clinical and biochemical syndrome, caused by injury and destruction of skeletal muscles. It is accompanied by pain in the region of the referred muscle group, increase in creatine phosphokinase levels, myoglobinuria, often with severe renal failure, and finally multi-organ system failure and death, if not treated in time. The main risk factor in the development of postoperative rhabdomyolysis is prolonged intraoperative immobilization of the patient. Morbidly obese patients who undergo laparoscopic bariatric operations should be considered high-risk for rhabdomyolysis, from extended immobilization and pressure phenomena in the lumbar region and gluteal muscles. We report a 20-year-old woman with BMI 51, who underwent a prolonged laparoscopic Roux-en-Y gastric bypass. Postoperatively, she presented severe myalgia in the gluteal muscles and lumbar region, oliguria and creatine phosphokinase levels that reached 38,700 U/L. She was treated with intensive hydration and analgesics, and did not develop acute renal failure because diagnosis and treatment were attained immediately.

Management of ureteral stones in pediatric patients.

PURPOSE: We report our 5-year experience in the management of ureteral stones in pediatric patients using shockwave lithotripsy (SWL) in combination with ureteroscopy. PATIENTS AND METHODS: A total of 25 children (age range 12 months-14 years; mean 8.7 years) underwent SWL for ureteral lithiasis. Stones were located in the upper ureter in 6 children (24%), the middle ureter in 8 (32%), and the lower ureter in 11 (44%). Their size ranged from 5 to 14 mm (mean 10.9 mm). The children who failed SWL underwent ureteroscopic treatment. RESULTS: In the SWL-only group, the overall stone clearance rate at 3 months was 84% (21 of 25 children). Four children (16%) who failed SWL underwent successful ureteroscopic treatment. Complications were infrequent and generally minor in both groups. CONCLUSIONS: Shockwave lithotripsy is a safe and efficient treatment modality for ureteral stones in pediatric patients. In expert hands, ureteroscopy can be successfully applied in case of SWL failure.

Intraureteral metallic endoprosthesis in the treatment of ureteral strictures.

OBJECTIVE: We report our experience on intraureteral metallic stents placement for the treatment of malignant and benign ureteral strictures. METHODS: Eight patients (six men and two women) with inoperable malignant or benign ureteral strictures, underwent insertion of metallic stents through percutaneous tracts. Six lesions (three malignant, three benign) involved ureterointestinal anastomoses after cystectomy for bladder cancer and ureteroileal urinary diversion or bladder substitution, and two malignant lesions involved the midureter. Self-expandable stents were used in seven cases and a balloon-expandable stent in the remaining one case. One stent was sufficient in seven ureters, and in one ureter, two overlapping stents were placed. RESULTS: Metallic stents were inserted without technical difficulties in all obstructed ureters and patency was achieved in all patients. Ultrasonography revealed resolution of pre-existing hydronephrosis. The duration of follow-up was 6-17 months (mean, 9 months). One ureter was occluded 8 months after stent placement because of ingrowth of tumor and granulation tissue. The other ureters showed no signs of obstruction during follow-up. No major complications directly attributable to the metallic stent occurred. CONCLUSIONS: Our results suggest that insertion of a metallic stent in the ureter is feasible and safe for the treatment of benign or malignant ureteral strictures. However, more work needs to be done to establish the use of these stents for the treatment of ureteral obstruction.

Nerve tissue-specific (GLUD2) and housekeeping (GLUD1) human glutamate dehydrogenases are regulated by distinct allosteric mechanisms: implications for biologic function.

Human glutamate dehydrogenase (GDH), an enzyme central to the metabolism of glutamate, is known to exist in housekeeping and nerve tissue-specific isoforms encoded by the GLUD1 and GLUD2 genes, respectively. As there is evidence that GDH function in vivo is regulated, and that regulatory mutations of human GDH are associated with metabolic abnormalities, we sought here to characterize further the functional properties of the two human isoenzymes. Each was obtained in recombinant form by expressing the corresponding cDNAs in Sf9 cells and studied with respect to its regulation by endogenous allosteric effectors, such as purine nucleotides and branched chain amino acids. Results showed that L-leucine, at 1.0 mM:, enhanced the activity of the nerve tissue-specific (GLUD2-derived) enzyme by approximately 1,600% and that of the GLUD1-derived GDH by approximately 75%. Concentrations of L-leucine similar to those present in human tissues ( approximately 0.1 mM:) had little effect on either isoenzyme. However, the presence of ADP (10-50 microM:) sensitized the two isoenzymes to L-leucine, permitting substantial enzyme activation at physiologically relevant concentrations of this amino acid. Nonactivated GLUD1 GDH was markedly inhibited by GTP (IC(50) = 0.20 microM:), whereas nonactivated GLUD2 GDH was totally insensitive to this compound (IC(50) > 5,000 microM:). In contrast, GLUD2 GDH activated by ADP and/or L-leucine was amenable to this inhibition, although at substantially higher GTP concentrations than the GLUD1 enzyme. ADP and L-leucine, acting synergistically, modified the cooperativity curves of the two isoenzymes. Kinetic studies revealed significant differences in the K:(m) values obtained for alpha-ketoglutarate and glutamate for the GLUD1- and the GLUD2-derived GDH, with the allosteric activators differentially altering these values. Hence, the activity of the two human GDH is regulated by distinct allosteric mechanisms, and these findings may have implications for the biologic functions of these isoenzymes.