Electric modulation of conduction in multiferroic Ca-doped BiFeO3 films.

Many interesting materials phenomena such as the emergence of high-Tc superconductivity in the cuprates and colossal magnetoresistance in the manganites arise out of a doping-driven competition between energetically similar ground states. Doped multiferroics present a tantalizing evolution of this generic concept of phase competition. Here, we present the observation of an electronic conductor-insulator transition by control of band-filling in the model antiferromagnetic ferroelectric BiFeO3 through Ca doping. Application of electric field enables us to control and manipulate this electronic transition to the extent that a p-n junction can be created, erased and inverted in this material. A 'dome-like' feature in the doping dependence of the ferroelectric transition is observed around a Ca concentration of approximately 1/8, where a new pseudo-tetragonal phase appears and the electric modulation of conduction is optimized. Possible mechanisms for the observed effects are discussed on the basis of the interplay of ionic and electronic conduction. This observation opens the door to merging magnetoelectrics and magnetoelectronics at room temperature by combining electronic conduction with electric and magnetic degrees of freedom already present in the multiferroic BiFeO3.

Unilateral paravertebral block: an alternative to conventional spinal anaesthesia for inguinal hernia repair.

BACKGROUND: Inguinal herniorrhaphy can be successfully performed using general, regional or local anaesthesia. Paravertebral block (PVB) has been used for unilateral procedures such as thoracotomy, breast surgery, chest wall trauma, hernia repair or renal surgery. METHODS: We compared unilateral lumbar PVB with conventional spinal anaesthesia (SA) in 60 consenting ASA I and II males aged 18-65 years, scheduled for unilateral inguinal hernia repair. Patients were randomly assigned into two groups, P (n=30) or S (n=30) to receive either PVB or SA, respectively. Two patients (7%) in group P had to be converted to general anaesthesia due to block failure. During surgery, patients of both groups received intravenous infusion of propofol titrated to light sedation. RESULTS: The time to first post-operative analgesic requirement (primary outcome measure) as 342 +/- 73 min in group P and 222 +/- 22 min in group S (P<0.0001). Time to ambulation was 234 +/- 111 min in group P and 361 +/- 32 min in group S (P<0.0001). Urinary retention requiring catheterization were found in zero (0%) patients in group P compared with five (16%) in group S (P=0.024). CONCLUSION: It can be concluded that unilateral PVB is more efficacious than conventional SA in terms of prolonging post-operative analgesia and reducing morbidities in patients undergoing elective unilateral inguinal hernia repair.

Intravenous infusion of ketamine-propofol can be an alternative to intravenous infusion of fentanyl-propofol for deep sedation and analgesia in paediatric patients undergoing emergency short surgical procedures.

BACKGROUND: Paediatric patients often present with different painful conditions that require immediate surgical interventions. Despite a plethora of articles on the ketamine-propofol combination, comprehensive evidence regarding the suitable sedoanalgesia regime is lacking due to heterogeneity in study designs. METHODS: This prospective, randomized, double-blind, active-controlled trial was conducted in 100 children, of age 3-14 years, American Society of Anesthesiologist physical status IE-IIE, posted for emergency short surgical procedures. Patients were randomly allocated to receive either 2 mL of normal saline (pre-induction) plus calculated volume of drug from the 11 mL of ketamine-propofol solution for induction (group PK, n=50) or fentanyl 1.5 µg/kg diluted to 2 mL with normal saline (pre-induction) plus calculated volume of drug from the 11 mL of propofol solution for induction (group PF, n=50). In both the groups, the initial bolus propofol 1 mg/kg i.v. (assuming the syringes contained only propofol, for simplicity) was followed by adjusted infusion to achieve a Ramsay Sedation Scale score of six. Mean arterial pressure (MAP) was the primary outcome measurement. RESULTS: Data from 48 patients in group PK and 44 patients in group PF were available for analysis. Hypotension was found in seven patients (14.6%) in group PK compared with 17 (38.6%) patients in group PF (P=0.009). Intraoperative MAP was significantly lower in group PF than group PK when compared with baseline. CONCLUSION: The combination of low-dose ketamine and propofol is more effective and a safer sedoanalgesia regimen than the propofol-fentanyl combination in paediatric emergency short surgical procedures in terms of haemodynamic stability and lesser incidence of apnoea.

Paravertebral block can be an alternative to unilateral spinal anaesthesia for inguinal hernia repair.

BACKGROUND: Inguinal hernia repair can be performed under satisfactory anaesthetic conditions using general, regional and peripheral nerve block anaesthesia. Unilateral spinal anaesthesia provides optimal anaesthesia, with stable haemodynamics and minimal adverse events. The paravertebral block, being segmental in nature, can be expected to produce some advantages regarding haemodynamic stability and early ambulation and may be a viable alternative. METHODS: Fifty-four consenting male patients posted for inguinal hernia repair were randomized into two groups, to receive either the two-segment paravertebral block (group-P, n=26) at T10 and L1 or unilateral spinal anaesthesia (group-S, n=28), respectively. The time to ambulation (primary outcome), time to the first analgesic, total rescue analgesic consumption in the first 24-hour period and adverse events were noted. RESULTS: Block performance time and time to reach surgical anaesthesia were significantly higher in the patients of group-P (P<0.001). Time to ambulation was significantly shorter in group-P compared to group-S (P<0.001), while postoperative sensory block was prolonged in patients of group-S; P<0.001. A significantly higher number of patients could bypass the recovery room in group-P compared to group-S, (45% versus 0%, respectively, P<0.001). No statistically significant difference in adverse outcomes was recorded. CONCLUSION: Both the paravertebral block and unilateral spinal anaesthesia are effective anaesthetic techniques for uncomplicated inguinal hernia repair. However, the paravertebral block can be an attractive alternative as it provides early ambulation and prolonged postoperative analgesia with minimal adverse events.

Airway management of two patients with penetrating neck trauma.

SUMMARY: Direct trauma to the airway is a rare injury which can lead to disastrous consequences due to compounding effect of bleeding, aspiration of blood, airway obstruction and severe sympathetic stimulation. Here we are presenting two cases of open tracheal injury in two adult males following assault with sharp weapon. Two different techniques of securing the airways were employed depending upon the severity and urgency of the situation. In the first case, orotracheal intubation helped the surgeon to repair airway around the endotracheal tube whereas in the second patient this stenting effect was absent as he was intubated through the distal cut-end of trachea in the face of airway emergency.

Ketamine-diazepam anaesthesia in surface and major plastic surgical operations.

Ketamine hydrochloride seems to be equally suitable for surface and major plastic surgical operations where controlled ventilation is required. Controlled ventilation performed by less amount of muscle relaxant where patients were ventilated with air only sparing the O2 and N2O. Fifty patients undergoing various operations including major plastic surgery were divided into two groups. In group A, an infusion of 500 mg ketamine hydrochloride, 20 mg diazepam in 500 ml of 5% dextrose was used as anaesthetic and in group B, the same drip was started and pancuronium bromide 0.08 mg/kg IV was given when eyelash reflexes were lost. Mean durations of anaesthesia were 70.4 minutes and 90.2 minutes in groups A and B respectively. Mean doses of ketamine hydrochloride required were 310 mg and 370 mg in groups A and B respectively. Decurarisation was done in usual way in group B patients. The induction, maintenance and recovery were smooth and uneventful in all cases. Moreover no difficulty was encountered in reversing residual curarisation in any of the patients in group B. Mean rise of systolic BP was 12.5 mm Hg and that of pulse rate was 20/minute in group A. In group B, mean rise of systolic BP was 10 mm Hg and that of pulse rate was 16/minute.