Author Response.

How to cite this article: Vaithialingam B, Gopal S, Masapu D. Author Response. Indian J Crit Care Med 2024;28(1):87-88.

Stimulation artefact on EEG trace with BIS monitoring during D-wave recording.

The D-wave reflects the corticospinal fibre potentials and is frequently recorded intraoperatively for intramedullary spinal tumours to ensure maximum safe resection. A 38-year-old male had an intramedullary spinal cord tumour surgically removed while being monitored with D-wave from a single distal electrode technique. Total intravenous anaesthesia (TIVA) with propofol (without a muscle relaxant and with intermittent intravenous fentanyl boluses) was used for the maintenance of anaesthesia guided by processed electroencephalography (EEG) using a bispectral index (BIS®) monitor. Regular spike artefacts were observed in the EEG signal recorded by the BIS® monitor during the application of the single-pulse transcranial electrical stimulus and were used as a visual indicator of stimulus delivery. Finally, we propose a novel method of confirming stimulus delivery during D-wave recording based on stimulation artefacts in the EEG signal recorded by the BIS® monitor.

"Locked-in State" Following Anterior Circulation Aneurysmal Subarachnoid Hemorrhage.

How to cite this article: Vaithialingam B, Gopal S, Masapu D. "Locked-in State" Following Anterior Circulation Aneurysmal Subarachnoid Hemorrhage. Indian J Crit Care Med 2023;27(8):601-602.

A Comparative Study of Midazolam and Target-Controlled Propofol Infusion in the Treatment of Refractory Status Epilepticus.

BACKGROUND: The recommended treatment for refractory status epilepticus (RSE) is the use of anesthetic agents, but evidence regarding the agent of choice is lacking. This study was designed to compare target-controlled infusion of propofol versus midazolam for the treatment of RSE regarding seizure control and complications. METHODS: This prospective, randomized study recruited 23 adult patients with RSE due to any etiology and treated with either propofol or midazolam titrated to clinical seizure cessation and gradual tapering thereafter. The primary outcome measure was seizure control and the secondary outcomes were duration of the Intensive Care Unit stay and duration of mechanical ventilation, occurrence of super RSE (SRSE), and complications. RESULTS: We recruited 23 patients (male:female = 18:5) into this study (propofol Group-11; midazolam Group-12). Overall, seizure control was noted in 34.8%, with successful seizure control in 45% of patients in the propofol group and 25% in midazolam group (P = 0.4). Mortality was similar in both the groups (propofol group [8/11; 72.7%] compared to the midazolam group [7/12; 58.3%] [P = 0.667]). The duration of hospital stay was significantly shorter in the propofol group compared to midazolam (P = 0.02). The overall incidence of SRSE was 69.5% in this study. The complication rate was not significantly different between the groups. CONCLUSIONS: The choice of anesthetic agent does not seem to affect the overall outcome in RSE and SRSE. Target-controlled propofol infusion was found to be equal in its efficacy to midazolam for the treatment of RSE. High mortality might be due to SRSE secondary to the underlying brain pathology.

Effect of adjunctive dexmedetomidine on anesthesia and analgesia requirement and recovery characteristics during Bispectral Index-guided anesthesia for cerebello-pontine angle surgeries: A randomized clinical trial.

BACKGROUND AND AIMS: The study was conceived to elucidate the effects of dexmedetomidine as an anesthetic adjunct to propofol (total intravenous anesthesia) on anesthetic dose reduction and anesthesia recovery parameters in cerebello-pontine angle (CPA) surgeries. MATERIAL AND METHODS: This prospective randomized study was conducted on 49 patients (25 with dexmedetomidine, 24 without). After standardized anesthetic induction, anesthesia was maintained using propofol (via target controlled infusion, titrated to maintain BIS between 40 and 60), fentanyl (0.5 µg/kg/hour) and either dexmedetomidine (0.5 µg/kg/hour) or a sham infusion. Neuromuscular blocking agents were excluded to allow cranial nerve EMG monitoring. Adverse hemodynamic events, recovery parameters (time to opening eyes, obeying commands, and extubation) and postoperative sedation score, shivering score, nausea, and vomiting score were recorded. RESULTS: Propofol and fentanyl utilization (as total dose, adjusted for duration of surgery and body weight, and number of extra boluses) was significantly lower in the dexmedetomidine group. There was no difference in any of the recovery parameters between the two groups. Incidence of bradycardia was significantly higher with dexmedetomidine, while no difference was found for hypotension, hypertension, and tachycardia. CONCLUSION: Dexmedetomidine-fentanyl-propofol anesthesia compares favorably with fentanyl-propofol anesthesia during CPA neurosurgical procedures with regard to anesthesia recovery times, but with lower intraoperative opioid and hypnotic utilization rates.

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.

Massive Congestive Facial and Submandibular Oedema Due to Extreme Neck Flexion Following Suboccipital Craniectomy: A Case Report.

A variety of factors could contribute to facial oedema during a prone neurosurgical procedure. For optimal surgical exposure, suboccipital cranial surgeries frequently necessitate extreme neck flexion. Extreme neck flexion in the prone position can impair venous drainage of the facial and oropharyngeal structures, leading to life-threatening oedema, so a two-fingerbreadth space between the chin and the sternum is critical. We present a case of massive facial oedema with submandibular swelling in a patient who underwent foramen magnum decompression in the prone position for Arnold Chiari malformation.

Customized and Cost-Effective 3D Printed Mold for Cranioplasty: India's First Single Center Experience.

CONTEXT: Autologous bone is the most commonly used flap in cranioplasty to repair the defect; however, synthetic materials are available. Poly methyl methacrylate (PMMA) is an effective polymer owing to its thermoplastic and radiolucent properties comparable to bone strength. Three-dimensional (3D) printing combined with computer-assisted design (CAD) is a simple, low-cost method to print molds that ensure surgical success. MATERIALS AND METHODS: A total of 114 patients underwent cranioplasty (July 2015-April 2018), and 25 of them using 3D printed template molds due to unavailability of autologous bone. The clinical features, patient demographics, and surgical parameters were analyzed. The visual analog score for cosmesis (VASC) and Odom's score was obtained pre and post-op. RESULTS: The mean age of the patients is 38.4 ± 14.6 years (Range, 9-66). The primary pathology for undergoing craniectomy is stroke (n = 13; 52%), traumatic brain injury (10; 40%) and tumor (2; 8%). The reason for nonavailability of flap was infection (n = 14;56%), flap resorption (4;16%), and trauma or tumor (7;28%). The mean time for manufacturing the 3D printed template is 13.2 ± 2.1 h. On follow-up, median Odom's score is excellent in 52% of cases, good in 40%, and fair in 8%. The mean VASC score on follow up is 8.2 ± 1.3. Three patients developed minor postoperative complications. CONCLUSION: This is the first study from a single tertiary care center in India to systematically evaluate the outcomes in 3D cranioplasty using CAD and 3D printing technology. This method would be optimal especially in developing countries since PMMA is cost effective and also gives an ideal cosmetic effect.

Multimodal Intraoperative Neurophysiological Monitoring in Spine Surgeries: The Experience at a Spine Centre through Years.

STUDY DESIGN: Retrospective observational study. PURPOSE: To share our experience of multimodal intraoperative neurophysiological monitoring (IONM) used in Sakra World Hospital, Bengaluru in various spine surgeries. OVERVIEW OF LITERATURE: The development of new onset postoperative neurological deficits can be completely avoided. In order to avoid these, IONM has become a standard of care in recent times for early detection and manipulation of the surgical procedure to prevent postoperative neurological deficits. METHODS: This retrospective study was performed on 408 patients who had undergone spine surgeries with IONM during April 2014 to March 2020 at a single center. The operative report, anesthesia record, and IONM were reviewed. All the patients were reassessed for postoperative neurological deficits in the postoperative period and followed up based on the intraoperative findings and neurological deficits for 4 weeks. Signal changes in IONM were reviewed, and the obtained results were further categorized into true positive, true negative, false positive, or false negative. If changes were observed during the IONM, the patients were managed as per the algorithm. RESULTS: Of the 408 patients being monitored continuously during the intraoperative period, 38 showed changes in recordings, 28 developed postoperative neurological deficits, and one developed neurological deficit without any change in the IONM. Nine patients had transient neurological deficits, and the other 20 had permanent neurological deficits. Overall, the multimodal IONM used in our study had a sensitivity of 96.6%, specificity of 97.4%, a positive predictive value of 73.7%, and a negative predictive value of 99.7%. CONCLUSIONS: Use of decision algorithm and multimodal neuromonitoring consisting of motor evoked potentials, somatosensory evoked potentials, and electromyography complement each other in the detection of neurological injury during the course the surgery, improve intraoperative care, and prevent further damage and morbidity in patients.

Intraoperative aberrant bispectral index values due to facial nerve monitoring.

Bispectral index is an accepted depth of anaesthesia monitor for guiding intraoperative hypnotic agent administration. Frontalis EMG displayed on BIS monitor may increase due to twitching of frontalis muscle. EMG increases are also known to cause artefactual increases in BIS values. We report a case of artefactual increase of EMG and subsequently BIS values, due to electrical artefact from cranial nerve stimulator being used to identify the facial nerve. An explanation of the effect of stimulator signal on BIS EMG and BIS values has been provided.

Simple Cost-Effective Alternative to Fluid and Blood Warming System to Prevent Intraoperative Hypothermia.

Fluid and blood warming devices are useful in situations of massive transfusions and in pediatric patients. However, the initial cost and disposable nature of many of these devices are a major hindrance in their efficient utilization. We report a simple cost-effective means of warming blood and other fluids, consisting of intravenous tubing coiled around the hose of a convective body warmer before its connection to the patient. A simple experiment using normal saline as fluid and a plastic bottle as a receptacle was also conducted to quantitate and validate the temperature rise by our technique. Overall temperature increase was a mean (± SD) of 6.11°C ± 3.17°C. The rise in temperature was highest (7.57°C ± 3.88°C) with flow rates below 10 mL/min and a higher temperature setting of 42°C. Such low-cost techniques help overcome resource deficits in developing countries and improve patient care.

Airway Management in an Infant With Huge Hydrocephalus.

Huge hydrocephalus is defined as a head circumference larger than the length of the child. We discuss the perioperative anesthetic management of a case of huge hydrocephalus during ventriculoperitoneal shunt placement, focusing primarily on the airway management. The patient was a 4-month-old with a midline supratentorial lesion causing obstructive hydrocephalus due to compression of the sylvian aqueduct. For optimum positioning for direct laryngoscopy, a pillow was placed below the baby's torso, to achieve a slight extension at the atlantoaxial joint. This maneuver decreased the angle between the line of vision and the laryngeal axis (calculated from the images), which effectively improved alignment.