Sriganesh Kamath

Importance of evidence-based medicine on research and practice.

© 2016 Indian Journal of Anaesthesia | Published by Wolters Kluwer Medknow Anaesthesia and evidence-based medicine (EBM) are considered as two of the 15 most important medical milestones.[1] The birth of anaesthesia on 16th October 1846 and the subsequent publication of this discovery as a case study 33 days later in the high-impact Boston Medical and Surgical Journal (the current New England Journal of Medicine) resulted in its widespread use that dramatically changed surgical practice.[2] Likewise, EBM, born at McMaster University in the early 90s, has had a considerable impact on the modern day health-care practice.[3]

376 The Salt Versus Sugar Debate: Urinary Sodium Losses Following Hypertonic Saline Administration Curtails Its Superior Osmolar Effect in Comparison to Mannitol in Severe Traumatic Brain Injury.

INTRODUCTION Osmotherapy forms an integral part in the management of patients with severe traumatic brain injury (TBI). An ideal choice between mannitol and hypertonic saline (HTS) remains to be conclusively proven. More importantly, attention has not been paid to the long-term osmolarity changes during the therapy. The current prospective randomized study aims at evaluating the effect of serum and urine osmolarity and sodium achieved with mannitol and HTS on intracranial pressure (ICP) and outcome. METHODS Thirty-eight patients of severe TBI, aged between 15 and 70 years and managed as per Brain Trauma Foundation (BTF) guidelines were allocated to receive equiosmolar doses of either 20% mannitol or 3% HTS for refractory intracranial hypertension. Demographic data, physiological variables, ICP, serum and urine osmolarity/sodium were collected over 5 days. Data were analyzed for relationship between serum and urine sodium over 5 days in patients receiving mannitol and HTS for severe TBI. RESULTS A total of 301 and 186 boluses of mannitol and HTS, respectively, were administered over 5 days. There was no difference between mannitol and HTS with respect to demography, type of brain injury and Glasgow Outcome Scale (GOS). Serum sodium and osmolarity changes were similar between the groups (P = .16 and 0.35, respectively). Urinary sodium excretion was significantly higher with HTS (P = .02). The mean fall in ICP following a dose of hyperosmolar agent was 8.9 ± 8.4 mm Hg in the mannitol group and 10.1 ± 8.7 mm Hg in the hypertonic saline group (P = 0.135). CONCLUSION During long-term administration of hyperosmolar agents in TBI, HTS is no more effective than mannitol in controlling ICP. A major reason for this lack of benefit is an increased urinary loss of sodium with HTS and consequent inability to achieve higher serum sodium and osmolarity levels. Therapy aimed at retaining sodium holds the key for superior osmolar effect and good outcome.

Acute Changes in the Cerebral Oximetry During Intraoperative Seizures: An NIRS-based Observation.

To JNA Readers: Near-infrared spectroscopy (NIRS) is a simple, noninvasive, bedside measurement of cerebral SaO2. 1 In epilepsy scenario, NIRS may be used to characterize the type of seizures or in monitoring patients recovering from status epilepticus.2,3 Intraoperative seizure detection is rare due to the effect of anesthetic agents on seizure activity. We describe the cerebral oximetry changes during intraoperative seizures using NIRS technology in a patient with arteriovenous malformation (AVM). A16-year-old female with a right frontal lobe AVM was posted for resection of AVM. She had no previous history of seizures, but received Phenytoin 800mg intravenous (IV) prophylactically before surgery. After anesthetic induction, regional oximetry system sensors were placed over the bilateral frontal region. Baseline regional oxygen saturation (rSO2) readings were 78% on the right (R) and 62% on the left (L). Anesthesia was maintained with oxygen/air/isoflurane, and anesthetic depth was titrated to a minimum alveolar concentration of 1. During the course of AVM resection, abrupt onset of bilateral generalized clonic movements was noted. Thiopentone 200mg IV bolus was administered to terminate the suspected seizure activity and isoflurane concentration was increased to achieve a minimum alveolar concentration of 1.2. During this seizure episode, the rSO2 on the left rapidly declined from 69% to 59%, and increased following administration of thiopentone injection to 80%. This change in rSO2 returned to baseline range over 12 minutes. A second seizure episode occurred on return of NIRS value to baseline, with decrease in NIRS value and increase following thiopentone bolus, although the magnitude of this change was smaller compared with the first event (Fig. 1). There was no significant change in the NIRS values on the right side during seizure but increase following thiopentone was observed on both the occasions. Patient received 500mg Levetiracitam IV following second episode and rest of the intraoperative course was uneventful without any recurrent seizure activity or delayed recovery. This report presents interesting observations. A baseline difference in the rSO2 in our patient (R>L) was seen. Higher content of oxygenated blood in the venous system due to highflow shunt through the right frontal AVM resulted in higher rSO2 value on the frontally placed NIRS sensor. As the rSO2 reflects the cumulative arterial, capillary and venous system with venous contribution being >70%, it is likely that higher rSO2 values were due to AVM-induced increased venous oxygen content. Secondly, the preexisting elevated regional blood flow on the right side from a high-flow AVM was sufficient to prevent desaturation during seizure (increased period of oxygen extraction) resulting in minimal change in rSO2, unlike on the left side. Finally, occurrence of a second seizure after 12 minutes when rSO2 returned to baseline suggests the possible decline in metabolic suppressive effect of thiopentone, and its probable duration of effect after a bolus. To conclude, in our patient, intraoperative seizures during AVM surgery resulted in significant changes in the rSO2 detected by NIRS-based technology. Analysis of these changes facilitated better understanding of the

Bezold Jarisch reflex and acute cardiovascular collapse during craniotomy

A 35-year-old man presented with insidious onset headache of 1 month duration and weakness of left upper and lower limbs. Computed tomography and magnetic resonance imaging of the brain demonstrated a large right parasagittal meningioma with oedema, mass effect on the ventricles and subfalcine herniation [Figure 1a]. He was initiated on anti-oedema measures before his scheduled surgery. The pre-operative investigations including an electrocardiogram were normal. The baseline heart rate was 72/min and blood pressure 130/90 mmHg. Standard anaesthetic induction and maintenance were performed. The patient received mannitol 20 g at the beginning of burr-hole placement. Twenty minutes later, as the bone flap was removed, sudden bradycardia (lowest heart rate of 30/min) and hypotension (arterial blood pressure of 70/30 mmHg) was noted [Figure 1b]. The end-tidal carbon dioxide (ETCO2) decreased from 31 to 28 mmHg, but oxygen saturation remained at 100%. At this point, the patient had received 1200 ml of crystalloids, and the urine output was 500 ml with blood loss of 300 ml. The surgeon was notified immediately who stopped the surgery, but cardiovascular changes persisted. Atropine 0.6 mg was administered intravenously, and 500 ml of crystalloid was rapidly infused following which heart rate and blood pressure improved to 82/min and 151/97 mmHg, respectively. Thereafter, haemodynamics remained stable throughout the surgery, and recovery was uneventful.

Comparison of suction above cuff and standard endotracheal tubes in neurological patients for the incidence of ventilator-associated pneumonia and in-hospital outcome: A randomized controlled pilot study

Background: Ventilator-associated pneumonia (VAP) is a common complication with endotracheal intubation. The occurrence of VAP results in significant mortality and morbidity. Earlier studies have shown reduction in the incidence of VAP with subglottic secretion drainage. The incidence of VAP in neurologically injured patients is higher and can impact the neurological outcome. This study aimed to compare the incidence of VAP with standard endotracheal tube (SETT) and suction above cuff endotracheal tube (SACETT) in neurologically ill patients and its impact on clinical outcome. Methods: Fifty-four patients with neurological illnesses aged ≥18 years and requiring intubation and/or ventilation and anticipated to remain on ETT for ≥48 h were randomized to receive either SETT or SACETT. All the VAP preventive measures were similar between two groups except for the difference in type of tube. Results: The data of 50 patients were analyzed. The incidence of clinical VAP was 20% in SETT group and 12% in SACETT group; (P = 0.70). The incidence of microbiological VAP was higher in the SETT group (52%) as compared to SACETT group (44%) but not statistically significant; (P = 0.78). There was no difference between the two groups for measured outcomes such as duration of intubation, mechanical ventilation, and Intensive Care Unit stay. Conclusions: In this pilot study in neurological population, a there was no significant difference in incidence of clinical and microbiological VAP was seen between SETT and SACETT, when other strategies for VAP prevention were similar. Other outcomes were similar with use of either tube for intubation.

Internet use among anaesthesiologists: A cross-sectional survey

Anaesthesiologists access the internet for both personal and professional reasons, and the global network has helped to bridge the information gap between developed and developing countries.[1] There are limited data regarding how anaesthesiologists professionally use the internet. The objectives of this study were to assess time spent by anaesthesiologists on the internet, as well as purposes and patterns of use.

Cervical spine tuberculosis and airway compromise

A ten-year-old child presented with neck pain and progressive paraparesis of two months’ duration. Magnetic resonance imaging (MRI) of the cervical spine showed a prevertebral abscess collection at the C7-T4 spinal level that was compressing the trachea (Figure). A diagnosis of spinal tuberculosis (i.e., Koch’s spine with Pott’s paraplegia) was suspected. The patient was scheduled for resection of the prevertebral abscess and posterior cervical spine stabilization via anterior fusion. As the child was uncooperative for awake fibreoptic intubation and both the clinical airway examination and MRI showed that the upper airway anatomy was relatively normal, we chose an inhalational anesthesia induction. After successful mask ventilation was confirmed and following administration of a muscle relaxant, direct laryngoscopy with orotracheal intubation was performed. A 6.5 mm armoured endotracheal tube (ETT) was secured at 18 cm depth after confirming equal air entry in both lungs. During decompression of the abscess, retraction was used for exposure, which resulted in an abrupt increase in airway pressure with decreased tidal volume and increased ETCO2 (to 50 mmHg). Fluoroscopy showed that the retractor was located just below the metallic portion of the armoured ETT, possibly compromising the softer distal ETT and/or the tracheal lumen. The ETT was advanced to 20 cm, and bilateral air entry was reconfirmed, after which ventilation and subsequent surgery were uneventful. A postoperative computed tomography scan revealed good stabilization of the cervical spine. The trachea was extubated 80 hr postoperatively. There was significant postoperative neurological improvement with the lower limb strength, on a scale of 0 to 5, increasing to a score of 4. The spinal column is involved in \ 1% of all cases of tuberculosis (TB). Cervical spine TB is even more rare, accounting for only 3-5% of all spinal TB cases. A tuberculous dorsal cervical prevertebral abscess with edema can distort normal airway anatomy, necessitating fibreoptic intubation. Unlike a previous report, our patient’s intubation was relatively easy, however, the ventilation was subsequently affected because the tip of the armoured ETT was compressed during surgical retraction, necessitating repositioning the ETT beyond the pathological area. Continued vigilance is clearly required not only during intubation but througchout the case.

Functional imaging in neurosciences

Recent advances in functional imaging of the brain have enabled a better understanding of the brain functions in health and disease. Amongst various functional imaging techniques, functional magnetic resonance imaging (fMRI) has been more rigorously employed in both clinical practice and in the research arena. This review will discuss the principles and techniques of fMRI, its role in understanding the pathophysiology of brain injury and finally, its clinical application in diagnosing neurological conditions and prognostication of outcome in patients with neurological disorders.

Anesthetic management during electroconvulsive therapy in a patient with burn injury

We could diagnose tumor migration only in the postanesthesia care unit; but this migration may have occurred earlier, possibly at the end of surgery or during patient repositioning. We should have performed fiberoptic bronchscopy after changing the Double Lumen Tube to single lumen tube and should have checked the tracheobronchial tree before shifting patient from OT, to avoid this life-threatening complication. We strongly recommend performance of flexible fibreoptic bronchoscopy routinely before and after ET tube change or extubation especially with excessive handling of tumor tissue.

Misinterpretation of minimum alveolar concentration: Importance of entering demographic variables

Indian Journal of Anaesthesia | Vol. 58 | Issue 4 | Jul-Aug 2014 504 arising from visceral organs upon the heart. Acta Neuroveg 1966;28:224-33. 7. Yamaguchi Y, Tsuchiya M, Akiba T, Yasuda M, Kiryu Y, Hagiwara T, et al. Nervous influences upon the heart due to overdistension of the urinary bladder: The relation of its mechanism to vago-vagal reflex. Keio J Med 1964;13:87-99. 8. Fagius J, Karhuvaara S. Sympathetic activity and blood pressure increases with bladder distension in humans. Hypertension 1989;14:511-7.