Effects of Intermittent Femoral Nerve Injections of Bupivacaine, Levobupivacaine, and Ropivacaine on Mitochondrial Energy Metabolism and Intracellular Calcium Homeostasis in Rat Psoas Muscle

Background: Long-acting local anesthetics cause muscle damage. Moreover, long-acting local anesthetics act as uncoupler of oxidative phosphorylation in isolated mitochondria and enhance sarcoplasmic reticulum Ca2+ release. The aim of the study was to evaluate effects of perineural injections of local anesthetics on mitochondrial energetic metabolism and intracellular calcium homeostasis in vivo.

Methods: Femoral nerve block catheters were inserted in adult male Wistar rats. Rats were randomized and received seven injections (1 ml/kg) of bupivacaine, levobupivacaine, ropivacaine, or isotonic saline at 8-h intervals. Rats were killed 8 h after the last injection. Psoas muscle was quickly dissected from next to the femoral nerve. Local anesthetic concentrations in muscle were determined. Oxidative capacity was measured in saponin-skinned fibers. Oxygen consumption rates were measured, and mitochondrial adenosine triphosphate synthesis rate was determined. Enzymatic activities of mitochondrial respiratory chain complexes were evaluated. Local calcium release events (calcium sparks) were analyzed as well as sarcoplasmic reticulum calcium content in saponin-skinned fibers.

Results: Eight hours after the last injection, psoas muscle concentration of local anesthetics was less than 0.3 [mu]g/g tissue. Adenosine triphosphate synthesis and adenosine triphosphate-to-oxygen ratio were significantly decreased in the muscle of rats treated with local anesthetics. A global decrease (around 50%) in all of the enzyme activities of the respiratory chain was observed. Levobupivacaine increased the amplitude and frequency of the calcium sparks, whereas lower sarcoplasmic reticulum calcium content was shown.     

New evidence from magnetic resonance imaging of brain changes after climbs at extreme altitude

The aim of the present study was to look for anatomical changes in climbers' brains, using magnetic resonance imaging (MRI), after extremely high-altitude climbs and to relate them to possible associated risk factors. Clinical history, neurological examinations and MRI were carried out on a group of nine climbers before and after climbing to over 7500 m without the use of supplementary oxygen. None of the subjects showed any neurological dysfunctions. In five climbers MRI abnormalities (high signal areas, cortical atrophy) were observed before the expedition. After the descent, two of them showed new high intensity signal areas recorded by MRI. Both subjects suffered severe neurological symptoms during the climb. The present study suggested that the brain changes observed by MRI could be related to the severity of clinical events at high altitude. However, we do not know the exact meaning of such MRI findings or the reason for their location, predominantly in posterior regions of the brain. The new evidence that a high percentage of climbers show MRI brain abnormalities, and especially the appearance of changes after the ascent, reinforces the possibility of a potential neurological risk in high-altitude climbing.     

Talectomy for clubfoot in arthrogryposis

We reviewed the results of 101 talectomies in 56 patients with arthrogrypotic clubfeet. The average age at the time of surgery was 4.3 years and the mean follow-up was 6 years. Talectomy was performed as a primary procedure in 16 feet and as a salvage procedure in 85 feet that underwent other surgical procedures before talectomy. We graded our results as good when the foot was plantigrade, able to wear regular shoes, pain free, and, very important, patient satisfaction. We used a chi2 statistical test and, after comparing results with age <4 to >4 years at time of surgery, tendo Achilles tenotomy, time of casting, radiological complete excision of talus, and transcalcaneal pin placement, only the immobilization time needed to be statistically significant to achieve a good result. We conclude that feet must be individualized for treatment and that, after reduction of the calcaneus in the mortise, a short leg cast must be placed for 8 weeks to maintain position and alignment.     

Pneumococcal peritonitis in adult patients: report of 64 cases with special reference to emergence of antibiotic resistance

BACKGROUND: Few data are available regarding pneumococcal peritonitis. We studied the clinical characteristics of intra-abdominal infections caused by Streptococcus pneumoniae and its prognosis in relation to antibiotic resistance. METHODS: We reviewed all cases of culture-proved pneumococcal peritonitis. Patients with liver cirrhosis and primary pneumococcal peritonitis were compared with patients with Escherichia coli peritonitis. RESULTS: Between January 1, 1979, and December 31, 1998, we identified 45 cases of primary pneumococcal peritonitis in patients with cirrhosis and 19 cases of secondary (or tertiary) pneumococcal peritonitis. Patients with cirrhosis and primary pneumococcal peritonitis vs those with primary E coli peritonitis had more frequent community-acquired infection, 73% vs 47%; pneumonia, 36% vs 2%; and bacteremia, 76% vs 33%; and higher attributable mortality (early mortality), 27% vs 9% (P<.05 for all). Secondary (or tertiary) pneumococcal peritonitis was associated with upper or lower gastrointestinal tract diseases; in most cases, the infection appeared after surgery. A hematogenous spread of S pneumoniae from a respiratory tract infection might be the most important origin of peritonitis; also, S pneumoniae might directly reach the gastrointestinal tract favored by endoscopic procedures or hypochlorhydria. There was an increased prevalence of penicillin and cephalosporin resistance up to 30.7% and 17.0%, respectively, although it was not associated with increased mortality rates. CONCLUSIONS: Primary pneumococcal peritonitis in patients with cirrhosis more often spread hematogenously from the respiratory tract and was associated with early mortality. In secondary (and tertiary) pneumococcal peritonitis, a transient gastrointestinal tract colonization and inoculation during surgery might be the most important mechanisms. Current levels of resistance were not associated with increased mortality rates.