Gyaninder Pal Singh

Predicting difficult laryngoscopy in acromegaly: a comparison of upper lip bite test with modified Mallampati classification.

Upper lip bite test (ULBT) is a simple test for predicting difficult intubation. However, it has not been evaluated in acromegalic patients. The primary aim of this study was to compare ULBT with modified Mallampati classification (MMPC) to predict difficult laryngoscopy in acromegalic patients. Over a 5-year period, 64 acromegalic and 63 nonacromegalic patients presenting for excision of pituitary tumor were enrolled. Preoperative airway assessment was done using MMPC and the ULBT. Under anesthesia, laryngoscopic view was assessed using Cormack-Lehane (CL) grading. MMPC III/IV and ULBT grade III were considered predictive of difficult laryngoscopy that was defined as Cormack-Lehane grades III or IV. Difficult intubation was defined as more than 2 direct laryngoscopy attempts involving change of blade or use of bougie/fiberoptic bronchoscope/intubating laryngeal mask airway. Sensitivity, specificity, positive and negative predictive values, and accuracy of both tests in predicting difficult laryngoscopy were calculated. Incidence of difficult laryngoscopy and intubation in acromegalics were 24% and 11%, respectively. MMPC and ULBT predicted difficulty in 61% and 14% acromegalics, respectively. However, only 26% and 44% of the laryngoscopies predicted to be difficult by MMMC and ULBT, respectively, were actually difficult. MMPC failed to predict 33% of difficult laryngoscopies whereas ULBT failed to predict 73%. Neither test predicted difficulty in 33% laryngoscopies that turned out to be difficult. Twenty-seven percent of the difficult laryngoscopies were correctly predicted by both tests. In acromegalic group, MMPC was more sensitive, whereas ULBT was more specific. Sensitivity and accuracy of both tests were less in acromegalic patients compared with nonacromegalic controls.

Effect of posture on mouth opening and modified Mallampati classification for airway assessment

Several bedside airway assessment methods have been proposed for preoperatively identifying patients who are difficult to intubate. To date, the Mallampati grading remains a time-tested technique for difficult airway assessment. Both Mallampati and the further modification by Samsoon and Young assessed patients in the seated position. During clinical practice, situations may arise where it may not be feasible for the patient to sit up for airway assessment. The aim of our prospective study was to determine whether there was any difference between the sitting and supine positions for the assessment of Mallampati grade. Eighty adult patients of American Society of Anesthesiologists (ASA) physical status I and II, aged 18–65 years, admitted to our neurosurgical ward were enrolled and assessed for airway. Our study revealed that change in posture produced a significant change in the mouth openings and Mallampati grades of the patients. This change was always toward a higher grade when the patient was turned supine from the sitting position.

EEG entropy values during isoflurane, sevoflurane and halothane anesthesia with and without nitrous oxide.

We hypothesized that like bispectral index, entropy may be anesthetic agent specific. We carried out a study to assess the entropy values of different anesthetics at equi-minimal alveolar concentrations (MACs) with air and nitrous oxide as carrier gases. Thirty adult patients undergoing spine surgery were randomized to receive halothane, isoflurane, or sevoflurane, in 2 stages, (a) with air/oxygen mixture (2:1) and (b) in nitrous oxide/oxygen (2:1). Heart rate, mean arterial blood pressure, response entropy (RE), and state entropy (SE) were noted at 1.0 and 1.5 MACs for each agent. Statistical analysis was done using the 2-way analysis of variance followed by Bonferroni correction and Student t test for paired data. P value of less than 0.05 were considered significant. The demographics and baseline values of heart rate, mean arterial blood pressure, RE, and SE were comparable. Changing from air/oxygen as carrier gas to 66% nitrous oxide in oxygen resulted in significant increase in both RE and SE at 1.0 MAC for all the agents (P<0.05). Among the agents, it was found that both RE and SE values were significantly higher during halothane anesthesia as compared with sevoflurane and isoflurane (P<0.05). At 1.5 MAC for all agents, after addition of nitrous oxide, there was an insignificant reduction in both RE and SE (P>0.05). Again the values of RE and SE remained high for halothane as compared with isoflurane and sevoflurane. In conclusion, our data suggest a possibility of misinterpretation of anesthetic hypnosis when entropy values increase with addition of nitrous oxide to 1 MAC isoflurane and sevoflurane.

A comparative evaluation of nitrous oxide-isoflurane vs isoflurane anesthesia in patients undergoing craniotomy for supratentorial tumors: A preliminary study

BACKGROUND Neuroanesthesiologists are a highly biased group; so far the use of nitrous oxide in their patient population is concerned. We hypothesized that any adverse consequence with use of nitrous oxide should affect the patient so as to prolong his/her stay in the hospital. The primary aim of this preliminary trial was to evaluate if avoidance of nitrous oxide could decrease the duration of Intensive Care Unit (ICU) and hospital stay after elective surgery for supratentorial tumors. PATIENTS AND METHODS A total of 116 consecutive patients posted for elective craniotomy for various supratentorial tumors were enrolled between April 2008 and November 2009. Patients were randomly divided into Group I: Nitrous oxide - Isoflurane anesthesia (Nitrous oxide-based group) and Group II - Isoflurane anesthesia (Nitrous oxide-free group). Standard anesthesia protocol was followed for all the patients. Patients were assessed till discharge from hospital. RESULTS The median duration of ICU stay in the nitrous group and the nitrous-free group was 1 (1 - 11 days) day and 1 (1 - 3 days) day respectively (P = 0.67), whereas the mean duration of hospital stay in the nitrous group was 4 (2 - 16) days and the nitrous free group was 3 (2 - 9) days (P = 0.06). The postoperative complications in the two groups were comparable. CONCLUSION From this preliminary study with a low statistical power, it appears that avoidance of nitrous oxide in ones practice may not affect the outcome in the neurosurgical patients. Further large systemic trials are needed to address this issue.

Predicting difficult laryngoscopy in acromegalic patients undergoing surgery for excision of pituitary tumors: A comparison of extended Mallampati score with modified Mallampati classification

Background: There are numerous reports of difficult laryngoscopy and intubation in patients with acromegaly. To date, no study has assessed the application of extended Mallampati score (EMS) for predicting difficult intubation in acromegalics. The primary aim of this study was to compare EMS with modified Mallampati classification (MMP) in predicting difficult laryngoscopy in acromegalic patients. We hypothesized that since EMS has been reported to be more specific and better predictor than MMP, it may be superior to the MMP to predict difficult laryngoscopy in acromegalic patients. Materials and Methods: For this prospective cohort study with matched controls, acromegalic patients scheduled to undergo pituitary surgery over a period of 3 years (January 2008-December 2010) were enrolled. Preoperative airway assessment was performed by experienced anesthesiologists and involved a MMP and the EMS. Under anesthesia, laryngoscopic view was assessed using Cormack-Lehane (CL) grading. MMP and CL grades of I and II were defined “easy” and III and IV as “difficult”. EMS grade of I and II were defined “easy” and III as “difficult”. Data were used to determine the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MMP and EMS in predicting difficult laryngoscopy. Results: Seventy eight patients participated in the study (39 patients in each group). Both MMP and EMS failed to detect difficult laryngoscopy in seven patients. Only one laryngoscopy was predicted to be difficult by both tests which was in fact, difficult. Conclusion: We found that addition of neck extension did not improve the predictive value of MMP.

Comparison of propofol versus sevoflurane on thermoregulation in patients undergoing transsphenoidal pituitary surgery: A preliminary study

Purpose: General anesthesia causes inhibition of thermoregulatory mechanisms. Propofol has been reported to cause more temperature fall, but in case of deliberate mild hypothermia, both sevoflurane and propofol were comparable. Thermoregulation is found to be disturbed in cases of pituitary tumors. We aimed to investigate which of the two agents, sevoflurane or propofol, results in better preservation of thermoregulation in patients undergoing transsphenoidal excision of pituitary tumors. Methods: Twenty-six patients scheduled to undergo transsphenoidal removal of pituitary adenomas were randomly allocated to receive propofol or sevoflurane anesthesia. Baseline esophageal temperature was noted. Times for temperature to fall by 1°C or 35°C and to return to baseline were also comparable (P>0.05). After that warmer was started at 43°C and time to rise to baseline was noted. Duration of surgery, total blood loss, and total fluid intake were also noted. If any, side effects such as delayed arousal and recovery from muscle relaxant were noted. Results: The demographics of the patients were comparable. Duration of surgery and total blood loss were comparable in the two groups. The time for temperature to fall by 1°C or 35°C and time to return to baseline was also comparable (P>0.05). No side effects related to body temperature were noted. Conclusion: Both propofol and sevoflurane show similar effects in maintaining thermal homeostasis in patients undergoing transsphenoidal pituitary surgery.

A retrospective analysis of perioperative complications during intracranial neuroendoscopic procedures: our institutional experience.

BACKGROUND Neuroendoscopic procedures are now being performed more frequently, and with advancement in technology, complications related to the procedure and equipments have also minimized or changed. We report our experience with 223 patients who underwent intracranial neuroendoscopic procedures. MATERIALS AND METHODS The rates of various perioperative complications, both surgical and anesthesia related, during intracranial neuroendoscopic surgeries were studied. Data collected included demographics, patients medical history and any associated comorbid conditions, diagnosis, procedure performed, anesthetic management, intraoperative and postoperative complications and outcomes. RESULTS Of the 223 patients studied, 119 were pediatric (age <14 years) and 104 were adults. Hypothermia (25.1%) and cardiovascular complications (such as tachycardia 18.8%, bradycardia 11.3%, hypertension 16.1%, and hypotension 16.6%) were the commonly observed complications during intraoperative period both in pediatric and adult patients. At the end of the procedure, delayed arousal was observed in 17 patients and 19 patients required postoperative ventilatory support. Postoperative frequent complications included: fever (34.1%), tachycardia (32.7%), nausea and vomiting (18.8%). Potentially fatal complications such as intraoperative hemorrhage, air embolism, etc. were rare. Most of the complications were transient and self-limiting. CONCLUSION Although endoscopic procedures are considered minimally invasive, at times may lead to life-threatening complications and one should be aware of them.

Stellate ganglion block for relieving vasospasms after coil embolization of basilar tip aneurysms.

To JNA Readers: Cerebral vasospasm is a major cause of disability and death in patients suffering from subarachnoid hemorrhage. Cervical sympathetic and stellate ganglion blocks (SGB) have been described to relieve vasospasm in anterior circulation. We report a case of a basilar tip aneurysm in which the patient developed right-sided hemiparesis after endovascular coiling. A 50-year-old man weighing 65 kg was admitted with complaints of severe headache, giddiness, and vomiting. The Glasgow coma score at admission was E4M6V5. His general physical examination was unremarkable, except for the presence of neck rigidity. His noncontrast computed tomographic (CT) scan revealed blood in the interpeduncular cistern. A diagnosis of subarachnoid hemorrhage Hunt and Hess grade II was made. On digital substraction angiography, a large basilar tip aneurysm measuring 7 6.6mm with a neck of 4.9mm was seen. Endovascular coiling under general anesthesia was planned. A 4 2 cm solitaire was deployed across the neck of the aneurysm crossing the left posterior cerebral artery up to its base. It was released without detaching. Another microcatheter was used to coil the aneurysm. During control angiogram, a thrombus starting from the upper basilar and left proximal posterior cerebral artery was seen. The thrombus was lysed with alteplase (4mg), but aneurysmal leak was noted. Protamine sulfate was given to neutralize the heparin effect, and bleeding stopped. The stent was recaptured and released. A check angiogram revealed basilar tip, bilateral posterior cerebral arteries filling normally. Dynamic CT showed mild subarachnoid hemorrhage with blood in the third and lateral ventricle. The patient was treated conservatively in the intensive care unit. On the third postprocedural day, the CT scan was normal, but the patient developed right-sided weakness. The development of this delayed neurological deficit was attributed to a vasospasm. However, transcranial Doppler (TCD) revealed normal velocities. The patient received intrathecal papaverine (20mg) twice a day and nimodipine (60mg) every 6 hours for 2 days, but no clinical improvement was noticed. On the basis of our previous experience we administered a SGB to the patient opposite to the side of the neurological deficit twice a day for 5 days. There was gradual improvement in limb weakness over this time, and the patient was discharged on day 15 with no residual deficits. Cervical sympathectomy obtained either through a cervical sympathetic block or a SGB has been shown to help patients with an evidence of vasospasm. The SGB has been shown to produce decreases in zero flow pressure, which is a surrogate marker of cerebral vascular tone as evaluated by TCD. The use of SGB has been shown to be of help in patients with anterior circulation aneurysms with TCD evidence of vasospasms. However, this is the first case report of utilization of this technique in a basilar tip aneurysm with delayed ischemic neurological deficit without demonstration of increased flow velocity on TCD examination. The predictive value of TCD has been well described to diagnose vasospasms in the middle cerebral artery. However, the relationship between TCD abnormalities and clinical worsening is unreliable for other vessels. SGB as an adjunct to standard treatment may be beneficial to reverse delayed ischemic neurological deficit due to vasospasms; however, there is a lack of randomized control trial.

Sudden Infant Death Syndrome – Role of Trigeminocardiac Reflex: A Review

Sudden infant death syndrome (SIDS) is an unexplained death in infants, which usually occurs during sleep. The cause of SIDS remains unknown and multifactorial. In this regard, the diving reflex (DR), a peripheral subtype of trigeminocardiac reflex (TCR), is also hypothesized as one of the possible mechanisms for this condition. The TCR is a well-established neurogenic reflex that manifests as bradycardia, hypotension, apnea, and gastric hypermotility. The TCR shares many similarities with the DR, which is a significant physiological adaptation to withstand hypoxia during apnea in many animal species including humans in clinical manifestation and mechanism of action. The DR is characterized by breath holding (apnea), bradycardia, and vasoconstriction, leading to increase in blood pressure. Several studies have described congenital anomalies of autonomic nervous system in the pathogenesis of SIDS such as hypoplasia, delayed neuronal maturation, or decreased neuronal density of arcuate nucleus, hypoplasia, and neuronal immaturity of the hypoglossal nucleus. The abnormalities of autonomic nervous system in SIDS may explain the role of TCR in this syndrome involving sympathetic and parasympathetic nervous system. We reviewed the available literature to identify the role of TCR in the etiopathogenesis of SIDS and the pathways and cellular mechanism involved in it. This synthesis will help to update our knowledge and improve our understanding about this mysterious, yet common condition and will open the door for further research in this field.

Acute hemodynamic instability during alcohol ablation of symptomatic vertebral hemangioma: A prospective study

Symptomatic vertebral hemangiomas (SVH) are difficult to treat and many therapeutic options, including surgery, radiotherapy, arterial embolization, and injection of methyl-methacrylate into hemagiomatous vertebrae have been reported. Alcohol ablation of vertebral hemangiomas is an effective management option; however, a literature search did not reveal any reports of anesthetic complications or hemodynamic instability during and report a series of four males and seven females and report hemodynamic variations observed at the time of injection of absolute ethanol under general anesthetic, for the treatment of SVH. The median age of the patients was 20 years (range, 10-36 years), and median weight was 45 kg (range, 30-70 kg). All patients developed transient hypotension and bradycardia at the time of alcohol injection (8-10 mL of absolute alcohol). No patient required intervention with vagolytics or vasopressors. It is likely that the administration of alcohol in small aliquots prevented any major consequences. Moreover, patients under general anesthesia are at lower risk than those receiving monitored sedation, with better control over hemodynamics.