Finite-size scaling of critical avalanches.

We examine probability distribution for avalanche sizes observed in self-organized critical systems. While a power-law distribution with a cutoff because of finite system size is typical behavior, a systematic investigation reveals that it may also decrease with increasing the system size at a fixed avalanche size. We implement the scaling method and identify scaling functions. The data collapse ensures a correct estimation of the critical exponents and distinguishes two exponents related to avalanche size and system size. Our simple analysis provides striking implications. While the exact value for avalanches size exponent remains elusive for the prototype sandpile on a square lattice, we suggest the exponent should be 1. The simulation results represent that the distribution shows a logarithmic system size dependence, consistent with the normalization condition. We also argue that for the train or Oslo sandpile model with bulk drive, the avalanche size exponent is slightly less than 1, which differs significantly from the previous estimate of 1.11.

Efficacy of clonidine as an adjuvant to ropivacaine in supraclavicular brachial plexus block: A prospective study.

BACKGROUND AND AIMS: Bupivacaine has been the most frequently used local anaesthetic in brachial plexus block, but ropivacaine has also been successfully tried in the recent past. It is less cardiotoxic, less arrhythmogenic, less toxic to the central nervous system than bupivacaine, and it has intrinsic vasoconstrictor property. The effects of clonidine have been studied in peripheral nerve blockade. The purpose of this study was to evaluate the effects of clonidine on nerve blockade during brachial plexus block with ropivacaine using peripheral nerve stimulator. METHODS: Sixty patients were randomly divided into two groups, Group A and B. Group A received 30 ml of 0.5% of ropivacaine with 0.5 ml normal saline while Group B received same amount of ropivacaine with 0.5 ml (equivalent to 75 µg) of clonidine for supraclavicular brachial plexus block. The groups were compared regarding quality of sensory and motor blockade, duration of post-operative analgesia and intra and post-operative complications. RESULTS: There was a significant increase in duration of motor and sensory block and analgesia in Group B as compared to Group A patients (P < 0.0001). There was no significant difference in onset time in either group (P = 0.304). No significant side effects were noted. CONCLUSION: The addition of 75 µg of clonidine to ropivacaine for brachial plexus block prolongs motor and sensory block and analgesia without significant side effects.

Perforation into gut by ventriculoperitoneal shunts: A report of two cases and review of the literature.

We report two cases of gastrointestinal perforation by ventriculoperitoneal (VP) shunts and review the literature on the topic. The time interval between shunt surgery and detection of bowel perforation is minimum in infants and increases with age. Sigmoid and transverse colon followed by stomach are the most frequent sites of gastrointestinal perforations by VP shunts.

Comparison of esmolol and labetalol, in low doses, for attenuation of sympathomimetic response to laryngoscopy and intubation.

OBJECTIVE: The present study compared the efficacy of esmolol and labetalol, in low doses, for attenuation of sympathomimetic response to laryngoscopy and intubation. DESIGN: Prospective, randomized, placebo controlled, double-blinded study. SETTING: Operation room. PATIENTS AND METHODS: 75 ASA physical status I and II adult patients, aged 18-45 years undergoing elective surgical procedures, requiring general anesthesia and orotracheal intubation. INTERVENTIONS: Patients were allocated to any of the three groups (25 each)-Group C (control)10 ml 0.9% saline i.v. Group E (esmolol) 0.5 mg/kg diluted with 0.9% saline to 10 ml i.v. Group L (labetalol) 0.25 mg/kg diluted with 0.9% saline to 10 ml i.v. In the control group 10 ml of 0.9% saline was given both at 2 and 5 min prior to intubation. In the esmolol group 0.5 mg/kg of esmolol (diluted with 0.9% saline to 10 ml) was given 2 min prior and 10 ml of 0.9% saline 5 min prior to intubation. In the labetalol group 10 ml of 0.9% saline was administered 2 min prior and 0.25 mg/kg of labetalol (diluted with 0.9% saline to 10 ml) 5 min prior to intubation. All the patients were subjected to the same standard anesthetic technique. MEASUREMENTS: Heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were recorded prior to induction, at time of intubation and 1, 3, 5, and 10 min after intubation. Mean arterial pressure (MAP) and rate pressure product (RPP) were calculated. Abnormal ECG changes were also recorded. RESULTS: Compared to placebo and esmolol (0.5 mg/kg), labetalol (0.25 mg/kg) significantly attenuated the rise in heart rate, systolic blood pressure, and RPP during laryngoscopy and intubation. However, the difference was not statistically significant among the values for DBP and MAP. CONCLUSION: In lower doses, labetalol (0.25 mg/kg) is a better agent than esmolol (0.5 mg/kg) in attenuating the sympathomimetic response to laryngoscopy and intubation.

A comparison between EMLA cream application versus lidocaine infiltration for postoperative analgesia after inguinal herniotomy in children.

BACKGROUND: EMLA cream (eutectic mixture of local anesthetics) has been shown to penetrate intact skin and provide analgesia of superficial layers. There are no studies on the effects of topical application of EMLA cream for postoperative pain relief after inguinal hernia repair. OBJECTIVE: : This randomized, double-blind, placebo-controlled study compared the efficacy of topical application of 5% EMLA cream before surgery, with wound infiltration with 1% lidocaine for postoperative analgesia in children. METHODS: Ninety children, aged 4 to 12 years, undergoing elective inguinal hernia repair under general anesthesia were enrolled in the study. Patients were randomly assigned to receive either placebo cream (group1), 5% EMLA cream (group 2), or placebo cream followed by 0.5 mL/kg 1% lidocaine (group 3) in the wound after induction of anesthesia. The anesthetic technique and monitoring were standardized, and postoperative pain was assessed using a 10-point objective pain scale. Fentanyl was used as rescue analgesic in immediate postoperative period, and acetaminophen was administered for postoperative pain in surgical ward. RESULTS: The number of patients requiring fentanyl in the immediate postoperative period was significantly less in the study groups compared with the placebo group. Sixty-seven percent of patients in the placebo group required more than 1 dose of acetaminophen in the first 6 hrs compared with 23% (EMLA group) and 20% (lidocaine group). Four patients (two in the lidocaine group, one in the EMLA group, and one in the control group) developed subcutaneous infection at the site of incision 10 to 15 days postoperatively. CONCLUSION: Topical application of EMLA (5%) provides postoperative analgesia comparable to infiltration with 1% lidocaine after inguinal hernia repair in children.

Nasogastric tube knotting with tracheoesophageal fistula - a rare association.

The nasogastric tube is used extensively in medical practice. However, this innocent-looking tube can at times cause unexpected complications especially in patients with preexisting risk factors. A 25-year-old male was referred to our hospital with a blocked and impacted nasogastric tube which had been inserted to maintain his nutritional status after he sustained a caustic injury to the esophagus in an attempted suicide. Esophagoscopy was done, the knotted nasogastric tube was retrieved and a tracheoesophageal fistula was detected at the site of impacted knot. However, the patient succumbed to ARDS and sepsis before definitive surgery could be done. Nasogastric intubation is not a simple procedure as is the general concept and it should not be done in cases of caustic injury to the esophagus because of increased risk of complications in the face of preexisting inflammation. To our knowledge, this is the first case report of its kind in the literature review.