Ashima Sharma

Analysis of Discharge Parameters in Xenon-Filled Coaxial DBD Tube

In this paper, a xenon-filled coaxial dielectric barrier discharge (DBD) has been studied to understand the high-pressure nonequilibrium nonthermal plasma discharge. A quartz coaxial DBD tube (ID: 6 mm, OD: 12 mm) at 400-mbar xenon-filled pressure has been used in the experiment. A unipolar pulselike voltage up to a-6-kV peak working at 30 kHz has been applied to the discharge electrodes for the generation of microdischarges. A single discharge is observed per applied voltage pulse. Visual images of the discharge and electrical waveform confirm the diffused-type discharges. The knowledge obtained by dynamic processes of DBDs in the discharge gap explains quantitatively the mechanism that is obtained in the ignition, development, and extinction of DBDs. The behavior of different discharge parameters has also been analyzed. From the experimental results and equivalent electrical circuit, the dynamic nature of equivalent capacitance has been reported. The relative intensity analysis of the Xe peak in the optical emission spectra (172 nm) has also been carried out for different supplied powers, and it is found that the radiation power has increased with supplied power.

Anticipation, planning and execution of airway strategy in McCune–Albright’s syndrome

SIR—We read with interest the article: ‘Bite blocks for use in pediatric anesthesia’ by Hasani A (1). Use of gauge roll as an alternative to bite block is a normal practice in our institute for both pediatric and adult patients receiving genome anesthesia and we have found it very useful (2). We would like to comment few points which have not been mentioned by the author. Use of soft airway as bite block is preferred for neurosurgery in sitting position because presence of hard airway is a precipitating factor for tongue edema due to obstruction of the venous and lymphatic drainage of the tongue. The use of gauze roll for bite block is especially useful as an alternative to soft airway in such situation. More than airway obstruction at extubation, as mentioned by Hasani as a potential complication, the gauze piece can get soaked in saliva and shrink in size to accidentally pass in to the stomach. The remedy to the problem of dislodgement is to avoid using undersized bite blocks. Puneet Khanna Mihir Prakash Pandia Department of Neuroanaesthesiology, All India Institute of Medical Sciences, New Delhi, India (email: mihirpandia@yahoo.co.in)

Evaluation of low-dose dexmedetomidine and neostigmine with bupivacaine for postoperative analgesia in orthopedic surgeries: A prospective randomized double-blind study

Background and Aims: Neuraxial adjuants to local anesthetics is an effective technique of improving the quality and duration of postoperative analgesia. The safety and efficacy of drugs like dexmedetomidine and neostigmine as epidural medications have been sparsely investigated. Material and Methods: Combined spinal-epidural anesthesia was performed in 60 American Society of Anesthesiologists I and II patients who required lower limb surgeries of ≤3 h duration. The epidural drug was administered at the end of surgery with patients randomized into three groups. Group I, II and III received 6 ml of 0.25% bupivacaine alone, with 1 ug/kg of neostigmine and with 0.5 ug/kg of dexmedetomidine + 1 ug/kg of neostigmine, respectively. The patients were prescribed 50 mg tramadol intravenous as rescue analgesic. Patients were assessed for hemodynamic parameters, pain scores, duration of analgesia, rescue analgesic requirements and the incidence of side-effects over the next 10 h. Data was analyzed using SPSS® version 17.0 (Chicago, IL, USA). P < 0.05 was considered as statistically significant. Results: Patients in Group III had significantly longer mean duration of analgesia (273.5 min) compared to Group II (176.25 min) and Group I (144 min). There was increased requirement of fluids to maintain blood pressures in Group III. Neostigmine did not cause significant incidence of gastrointestinal side effects. Conclusions: Epidurally administered dexmedetomidine and neostigmine exhibit synergism in analgesic action. The incidence of drug-related side-effects was low in our study.

An observational study of the feasibility of Airtraq guided intubations with Ring Adair Elvin tubes in pediatric population with cleft lip and palate

Context: The airway management requires refined skills and technical help when associated with cleft lip and palate. Airtraq has improved our airway management skills and has been successfully used for rescue intubation in difficult pediatric airways. Aims: This study was to evaluate the efficacy of Airtraq as the primary intubation device in patients with cleft lip and palate. The study adheres to the STrengthening the Reporting of OBservational Studies Epidemiology Statement. Subjects and Methods: A total of 85 children posted consecutively for lip and palate repair were enrolled. Children were intubated with Ring Adair Elvin (RAE) tube using size 1 and 2 of Airtraq device. The design of Airtraq has an anatomical limitation to hold RAE tubes. The preformed bend of the tube was straightened with a malleable stylet. The intubations were assessed for device manipulations and time taken for glottis visualization and intubation, airway complications such as bleeding, laryngospasm and failed intubations. Statistical Analysis Used: The outcome data were reported as numbers and percentages or range with identified median value, where applicable. Results: The success rate of Airtraq guided intubations was 98.21%. The cumulative insertion times and intubation times were 31.50 ± 12.57 s and 48.04 ± 35.73 s respectively. Airtraq manipulations were applied in 25.45% subjects. Conclusions: The presence of cleft lip or palate did not hamper the insertion of Airtraq. The use of malleable stylet to facilitate the loading of the preformed tube into the guide channel is a simple and efficacious improvisation. Airtraq can be utilized as a primary intubation device in children with orofacial clefts.

Differential cyanosis and undiagnosed eisenmenger's syndrome: The importance of pulse oximetry

Eisenmengers physiology has significant anesthetic implications. The symptamology, in the early course of disease can be subtle at times and missed on regular PAC. Pulse oximetry, in our patient detected differential saturations. The possibility of underlying congenital cardiac illness was assumed, rescheduling of case was debated and finally the abnormal cardiac lesions were identified in ECHO in immediate postoperative period.

Epidural catheter fixation. A comparison of subcutaneous tunneling versus device fixation technique

Background and Aims: The technique of securing the epidural catheter has a major bearing on the efficacy of epidural analgesia. Specific fixator devices, for e.g., Lockit epidural catheter clamp, which successfully prevents catheter migration, are available. The possibility of catheter snapping and surgical retrieval has been reported with tunneling of catheters. These techniques have not been compared for safety, efficacy and appropriateness of achieving secure epidural catheter fixation in the postoperative period. Material and Methods: A total of 200 patients who required postoperative epidural analgesia were included. They were randomized into two groups: Group I (n = 100) in whom epidural catheters were tunneled vertically in the paravertebral subcutaneous tissue and group II (n = 100) wherein a Lockit device was used to fix the catheter. Likert score was used to quantify patients comfort during procedure. The techniques were compared for migration, catheter dislodgement, local trauma, catheter snapping and catheter obstruction. Results: 12% of tunneled catheters had migrated significantly outward. 22% of patients had erythema and 77% had significant procedural discomfort in group I. In group II, 3% catheters had kinked and 14% had erythema from device adhesive. Conclusion: Our results support the use of Lockit device as a safe and comfortable fixation device compared to subcutaneous tunneling of catheters.

Maxillary tumor in child--improvization of airway assist device to aid intubation.

exchange catheter. The position of the endotracheal tube was verified by auscultation and capnography and the patient paralyzed before surgery was allowed to proceed. Anesthesia was maintained with oxygen, air, and sevoflurane. The surgical gingivectomy was uneventful and the patient recovered well. ISH shares many similarities with Juvenile hyaline fibromatosis (JHF) which is now believed to be a milder variant of ISH (2). JHF has a later onset and patients survive into adulthood. In previous reports of anesthetic management of JHF, Vaughn et al. reported a 13-month-old child whose trachea was intubated with the aid of a guidewire passed through the suction port of a fiberoptic bronchoscope (3). Norman et al. demonstrated that airway difficulties are likely to become more difficult in subsequent anesthetics as the disease progresses (4). Resistance to succinylcholine, but normal response to vecuronium have been observed in JHF (5). A variety of techniques has been described to manage the airway of patients with similar challenges. Gas induction is considered the safest method of induction while the airway remains unsecured. Depending on the nature of the procedure being performed, a laryngeal mask may be used to maintain the airway. However, insertion may be difficult because of oral and pharyngeal infiltration, or sometimes impossible if mouth opening is very limited. The nasal route can also be used. Norman et al. (4) used a nasal airway in one nostril to allow spontaneous ventilation and fiberoptically intubated the airway through the other nostril. There are limitations to the use of the fiberoptic intubating bronchoscope as it requires an anesthetist experienced in its use. Awake intubation is rarely practiced in young children. If the internal diameter of the tracheal tube required is less than the diameter of the bronchoscope available, it cannot be used to railroad the tube into the trachea. However, as we described, a guidewire can be passed down the suction port to avoid this limitation. In severe cases, it may be impossible to use any transoral technique to secure the airway. As reported by Seefelder et al. (5), it may be necessary in those situations to perform a fiberoptic-assisted nasotracheal intubation with the patient sedated but maintaining spontaneous respiration. Blind nasotracheal intubation may be an alternative to fiberoptic intubation. However, as with all nasal approaches, there is the possibility of bleeding and blind techniques may fail. Management options in case of failure of fiberoptic intubation are limited. An experienced pediatric ENT surgeon should be present to secure a surgical airway if required. This as well may be difficult because of limited neck mobility. Postoperative care requires attention. There may be an increased risk of airway obstruction particularly if postoperative analgesia is required. ISH can pose a serious airway challenge for the anesthetist. It is important to anticipate and to be prepared for a difficult airway situation. The choice of the anesthetic technique will depend on the experience of the individual anesthetist. However, it is essential that all appropriate equipment should be available and an experienced pediatric anesthetist and ENT surgeon are present for all such cases. Michael Pollard* Eshan M. Ollite* Robert W.M. Walker† *Specialist Registrars in Anaesthesia, North West Deanery, UK and †Consultant Anaesthetist, Royal Manchester Children’s Hospital, Manchester, UK (email: michaelfpolland@hotmail.com)

A comparative study of Sterofundin and Ringer lactate based infusion protocol in scoliosis correction surgery

Background: A major change in anesthesia practice as regards to intraoperative infusion therapy is the present requirement. Switching over to balanced fluids can substantially decrease the incidence of lactic acidosis and hyperchloremic acidosis. The deleterious effects of unbalanced fluids are more recognizable during major surgeries. We prospectively studied the influence of Sterofundin (SF) and Ringer lactate (RL) on acid–base changes, hemodynamics, and readiness for extubation during scoliosis surgery. Subjects and Methods: Thirty consecutive children posted for scoliosis surgery were randomized to receive either RL (n = 15) or SF (n = 15) as intraoperative fluid at 10 mg/kg/h. Fluid boluses were added according to the study fluid algorithm. Arterial blood was sampled and analyzed at hourly intervals during surgery. Red blood cell transfusion was guided by hematocrit below 27. Patients were followed for 24 h postoperatively in the Intensive Care Unit. Results: There was no statistically significant difference in the volume of infused fluid (2400 ± 512 ml in Group RL and 2200 ± 640 ml in Group SF. There were no significant changes in pH of patients infused with SF. Statistically, significant higher lactate levels were seen in RL-infused group. The strong ion difference was decreased in both groups, but it normalized earlier with SF. Conclusions: SF-infused patients had nonremarkable changes in acid–base physiology in scoliosis surgery.

Marble bone disease and the Anaesthesiologist

Sir, Osteopetrosis is an uncommon genetic disease encountered by anaesthesiologists and is rarely reported.[1] The various associated anatomical and physiological alterations are challenging. We report the successful management of a 35-year-old female with the condition, scheduled for revision surgery for malunion of femur under combined spinal-epidural block (CSE). Pre-operatively, difficult airway, atlantoaxial dislocation (AAD) and significant bony sclerosis of entire vertebral column were identified [Figure 1]. Figure 1 Vertebral column sclerosis The patient had received general anaesthetic 4 years before for fracture of the shaft of the femur. The fracture had malunited resulting in deformity, and a redo interlocking nail femur was planned. Patient was explained the need and the procedure of fibreoptic guided awake intubation, in case of failure of regional anaesthesia. The patient was 36 kg in weight, 138 cm tall with short limbs, frontal bossing, macrocephaly with no mental retardation, receding mandible and irregular dentition. Airway assessment revealed a high arched palate, restricted neck extension and a modified Mallampati airway grade 2b. Difficult intubation was anticipated. In view of AAD, advanced airway gadgets to prevent neck movements during laryngoscopy and intubation were kept ready. Substantial sclerosis of vertebral bodies was noticed in spine radiographs with almost fused spine in the lumbar region, thereby increasing the technical difficulty in performing the neuraxial blockade. The patient was pre-medicated with injection pantoprazole 40 mg and alprazolam 0.25 mg. The patient was verbally assured and could be comfortably positioned sitting for the neuraxial block. Needle through needle technique was used for CSE. Block was performed by paramedian approach in L2-L3 intervertebral space and was successful in the first attempt. Bupivacaine 0.5% heavy (10 mg) with fentanyl 12.5 μg was deposited intrathecally. The epidural catheter was fixed at 7 cm mark (space identified by loss of resistance to air at 2 cm from the skin). A sensory analgesia up to T10 dermatome was achieved. The patient was carefully positioned with adequate padding of pressure points. Tranexamic acid 10 mg/kg intravenous was administered during surgery. A fixed dose continuous epidural infusion containing bupivacaine 0.125% with fentanyl 1 μg/ml was started at 5 ml/h at the end of surgery for post-operative analgesia. Patient exhibited stable haemodynamics during surgery. The epidural catheter was removed on 3rd post-operative day. The patient did not exhibit any signs of post-operative neurological deterioration. Osteopetrotic patients[2] vary greatly in their presentation and severity. The simplest form is osteopoikilosis, noticed as incidental finding of osteopetrosis on radiographs. Autosomal recessive variant has a neonatal onset with fractures, short stature, compressive neuropathies, hypocalcaemia, tetanic seizures, pancytopenia, mental retardation, skin and immune system involvement and renal tubular acidosis. The onset of primarily skeletal manifestations such as fractures, osteoarthritis of hip joint and osteomyelitis of the mandible at adolescence is typical of autosomal dominant variant. Common findings are cranial nerve compressions manifesting as visual and hearing loss, nutritional anaemia, thrombocytopaenia, brittle and osteomyelitic bones (more prone to bleed), hypocalcaemic seizures with secondary hyperparathyroidism and muscular hypotonia. Judicious use of transfusions is warranted as significant immunosuppression is a feature of this disease. Nasal space is reduced by bony encroachments with disturbed facial anatomy complicating nasal intubation. Fibreoptic guided awake oral intubation is preferred if general anaesthesia is contemplated.[3] The anaesthetic options are limited and technically difficult with both airway and spine involved in the disease process. The osteopetrotic bones are difficult to drill and surgical time can escalate. We were able to successfully place a central neuraxial block in our patient, but this may not always be the best anaesthetic. Hence, pre-operative identification of anaesthetic complexities is essential to plan safe perioperative course.