The main aims of anesthesia for pituitary surgery include maintenance of hemodynamic stability, provision of conditions that facilitate surgical exposure, and a smooth emergence to facilitate a prompt neurologic assessment. The primary aim of our study was to compare the effects of 3 anesthetic regimens on hemodynamics and recovery characteristics of the patients. Ninety patients undergoing transsphenoidal surgery were enrolled in the study. Standard anesthesia technique was followed for induction. Patients were randomly divided to receive propofol, isoflurane, or sevoflurane for maintenance of anesthesia. The bispectral index target range during maintenance was 40 to 60. The hemodynamic variables (heart rate and mean arterial pressure) and bispectral index were noted during the various stages of the surgery. The time to emergence and extubation was noted. We evaluated cognitive function at 5 and 10 minutes posttracheal extubation. The 3 study groups were comparable with respect to age, sex, weight, and duration of surgery. We observed an increase in heart rate and blood pressure during intubation, nasal packing, and insertion of self-retaining nasal speculum. After tracheal intubation, the rise in blood pressure was more in sevoflurane group than propofol. During emergence, hypertensive response was seen in all patients. Emergence and extubation times were significantly shorter with propofol and sevoflurane. Patients who received propofol had better cognition scores. Aldrete scores were better with propofol and sevoflurane than isoflurane. The pressor response after intubation and emergence hypertension was significantly less with propofol. Better recovery profile was seen in sevoflurane and propofol groups and a better cognition in patients receiving propofol. Propofol plus nitrous oxide anesthesia could be the technique of choice in patients undergoing transnasal transsphenoidal pituitary surgery.

Mannitol is the most commonly used hyperosmotic agent in neurosurgery. Being an agent that increases intravascular volume by withdrawing water from the brain, it may cause significant changes in stroke volume (SV), cardiac output (CO), systemic vascular resistance and blood pressure. In this study, we monitored the hemodynamic changes in response to a single dose of mannitol by using a noninvasive CO monitor based on the thoracic electrical bioimpedance technique, in patients undergoing craniotomy. Eleven adult patients undergoing elective craniotomy received mannitol 1.0 g/kg 15 minutes before dural opening. The following hemodynamic variables were recorded: heart rate, systolic blood pressure, diastolic blood pressure, SV, CO, and cardiac index. The measurements were made before the administration of mannitol, at 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, and 45 minutes after the termination of the mannitol infusion. Urine output was measured at 10, 20, 30, 40, 50, 60, 90, and 120 minutes after termination of the mannitol infusion. Heart rate values from 25 to 45 minutes were significantly lower compared with the premannitol values (P<0.05). All the postmannitol systolic blood pressure values were significantly lower than the premannitol value (P<0.05). SV increased significantly for 15 minutes after administration of mannitol (P<0.05). SV at 45 minutes was significantly lower than that from 1 to 30 minutes (P<0.05). Cardiac index also showed a similar change with a significant increase at 1 to 10 minutes and a decrease at 40 to 45 minutes compared with 1 to 15 minutes.The rate of urine secretion was higher during the first 10 minutes (40+/-15 mL/kg/ h) than during the rest of the study period. The overall fluid balance at the end of 120 minutes was -370+/-987 mL. In this study using noninvasive measurement of CO by thoracic bioimpedance plethysmography during craniotomy, a single bolus dose of mannitol 1.0 g/kg caused a significant but short duration changes in the hemodynamic variables. The changes in SV, and CO, lasted for only 15 minutes after the infusion.

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.

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Management of the airway is central to the practice of anesthesia. Several bedside airway assessment methods have been proposed for preoperative identification of patients who are difficult to intubate. The modified Mallampati test (MMT) remains a time-tested technique to date for recognizing an anticipated difficult tracheal intubation as assessed by Cormack-Lehane grade. Both Mallampati and its further modification by Samsoon and Young evaluate patients in the seated position. Recently a study mentioned a change in MMT score from sitting to supine position toward the higher side. However, there is a lack of data regarding the relationship of positional change in MMT with Cormack-Lehane grade. The aim of this prospective study was to assess if MMT score observed in sitting or supine position is a better predictor of difficult tracheal intubation. One hundred and twenty-three patients of ASA physical status I and II, aged 18-60 years, who were scheduled to undergo various neurosurgical procedures were enrolled for the study. We found that the MMT in supine position has a higher positive predictive value and is associated with more true positives as compared to MMT in the sitting position.

Spontaneous spinal epidural haematoma (SSEH) is a rare cause of neurological deficit in the pregnant and post-partum patients. However, SSEH with associated myelitis presenting as quadriplegia and respiratory paralysis in the post-partum period has never been reported. We report the development of acute onset quadriplegia progressing to respiratory arrest in a 24-yr-old woman 2 weeks after normal vaginal delivery. There was no history suggestive of any coagulopathy (inherited or acquired), eclampsia, pre-existing neurological deficit, or iatrogenic manipulations such as spinal/epidural injections. Magnetic resonance imaging revealed a posterior epidural haematoma extending from C4-C7 and areas of signal changes in spinal cord from cervicomedullary junction to D5 level (suggestive of demyelination). We highlight this rare cause of quadriplegia; focusing on the altered dynamics of the epidural vasculature in the peripartum period leading to SSEH.

No abstract

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.