Zulfiqar Ali

Bispectral index-guided administration of anesthesia for transsphenoidal resection of pituitary tumors: a comparison of 3 anesthetic techniques.

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.

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.

Electrocardiographic changes due to vagosympathetic coactivation during the trigeminocardiac reflex.

To JNA Readership: Much has been mentioned in literature on the trigeminocardiac reflex (TCR) originating from the skull base surgery and other maxillofacial procedures. The role of autonomic nervous system activation is central to the occurrence of this reflex. The coactivation of sympathetic and parasympathetic nervous system in the occurrence of TCR has been suggested recently. We encountered a case where the TCR resulted in severe bradycardia along with changes in the electrocardiogram (ECG). An 18-year-old male, weighing 48kg presented with loss of vision and progressive protrusion of left eye since the age of 4 years, impaired hearing from right ear since 2 years, imbalance and gait disturbance since 1 year. Magnetic resonance imaging of brain showed an intensely enhancing soft-tissue mass lesion in the planum and suprasellar region with extension in the parasellar region and intraorbital area. He was scheduled for elective bifrontal craniotomy and tumor excision. All routine investigations were within normal limits. He was premedicated with glycopyrrolate of 0.2mg intramuscularly an hour before surgery. Two hours after starting of surgery under general tracheal anesthesia, during manipulation of the orbital extension of tumor, patient developed sudden bradycardia (heart rate dropped from 96beats/min to 54beats/ min) and subsequent fall in arterial blood pressure (from 140/84mm Hg to 92/48mm Hg). There was a concomitant inversion of T wave in ECG leads II and V. Immediate withdrawal of surgical stimulus brought heart rate and blood pressure back to normal in about 3 minutes, but T wave remained inverted. Blood gas and electrolyte values were within normal limits. Surgery was resumed uneventfully but the ECG changes persisted for another half an hour. At the end of the surgery, the patient was shifted to neurosurgical intensive care unit. A 24 hours Holter monitoring was performed, which revealed no abnormality. The patient was discharged from the hospital on the sixth postoperative day with no further neurologic and cardiac problem. Cardiorespiratory efferent fibers arising from the motor nucleus of the vagus terminate in the myocardium. These vagal stimuli provoke negative chronotropic and ionotropic responses. It has been demonstrated that the reflex is elicited both during peripheral and central stimulation of the trigeminal nerve. In a recent report by Schaller, et al, during the occurrence of TCR the authors noted bradycardia associated with simultaneous shortening of the QT interval in the ECG. It is known that autonomic influences on heart are generally weak. Parasympathetic fibers primarily innervate the atria and conducting tissues. In contrast, sympathetic fibers are more widely distributed throughout the heart. Vagal effects frequently have a very rapid onset and resolution; whereas sympathetic influences generally have a more gradual onset and dissipation. It is likely that activation of both, sympathetic-mediated vasoconstriction and parasympatheticmediated bradycardia produced characteristic ECG changes. Our observation is in consistence with that of Schaller who suggest myelinization status of the nerve may not be an important risk factor and phenotypic heterogeneity could be the basis of susceptibility for simultaneous autonomic nerve activation.

Pharmacological and non‐pharmacological interventions for reducing rocuronium bromide induced pain on injection in children and adults

BACKGROUNDnRocuronium bromide is a routinely used muscle relaxant in anaesthetic practice. Its use, however, is associated with intense pain on injection. While it is well established that rocuronium bromide injection causes pain in awake patients, anaesthetized patients also tend to show withdrawal movements of the limbs when this muscle relaxant is administered. Various strategies, both pharmacological and non-pharmacological, have been studied to reduce the incidence and severity of pain on rocuronium bromide injection. We wanted to find out which of the existing modalities was best to reduce pain on rocuronium injection.nnnOBJECTIVESnThe objectives of this review were to assess the ability of both pharmacological and non-pharmacological interventions to reduce or eliminate the pain that accompanies rocuronium bromide administration.nnnSEARCH METHODSnWe searched the Cochrane Central Register of Controlled Trials (CENTRAL 2013, Issue 7), MEDLINE via Ovid SP (1966 to July 2013) and EMBASE via Ovid SP (1980 to July 2013). We also searched specific websites. We reran the searches in February 2015 and will deal with the 11 studies of interest found through this search when we update the review.nnnSELECTION CRITERIAnWe included all randomized controlled trials (RCTs) that compared the use of any drug or a non-pharmacological method with control patients, or those receiving no treatment to reduce the severity of pain with rocuronium injection. Our primary outcome was pain on rocuronium bromide injection measured by a pain score assessment. Our secondary outcomes were rise in heart rate and blood pressure following administration of rocuronium and adverse events related to the interventions.nnnDATA COLLECTION AND ANALYSISnWe used the standardized methods for conducting a systematic review as described in the Cochrane Handbook for Systematic Reviews of Interventions. Two authors independently extracted details of trial methodology and outcome data from reports of all trials considered eligible for inclusion. We made all analyses on an intention-to-treat basis. We used a fixed-effect model where there was no evidence of significant heterogeneity between studies and a random-effects model if heterogeneity was likely.nnnMAIN RESULTSnWe included 66 studies with 7840 participants in the review, though most analyses were based on data from fewer participants. In total there are 17 studies awaiting classification. No studies were at a low risk of bias. We noted substantial statistical and clinical heterogeneity between trials. Most of the studies reported the primary outcome pain as assessed by verbal response from participants in an awake state but some trials reported withdrawal of the injected limb as a proxy for pain after induction of anaesthesia in response to rocuronium administration. Few studies reported adverse events and no study reported heart rate and blood pressure changes after administration of rocuronium. Lidocaine was the most commonly studied intervention drug, used in 29 trials with 2256 participants. The risk ratio (RR) of pain on injection if given lidocaine compared to placebo was 0.23 (95% confidence interval (CI) 0.17 to 0.31; I² = 65%, low quality of evidence). The RR of pain on injection if fentanyl and remifentanil were given compared to placebo was 0.42 (95% CI 0.26 to 0.70; I² = 79%, low quality of evidence) and (RR 0.10, 95% CI 0.04 to 0.26; I² = 74%, low quality of evidence), respectively. Pain on injection of intervention drugs was reported with the use of lidocaine and acetaminophen in one study. Cough was reported with the use of fentanyl (one study), remifentanil (five studies, low quality evidence) and alfentanil (one study). Breath holding and chest tightness were reported with the use of remifentanil in two studies (very low quality evidence) and one study (very low quality evidence), respectively. The overall rate of complications was low.nnnAUTHORS CONCLUSIONSnThe evidence to suggest that the most commonly investigated pharmacological interventions reduce pain on injection of rocuronium is of low quality due to risk of bias and inconsistency. There is low or very low quality evidence for adverse events, due to risk of bias, inconsistency and imprecision of effect. We did not compare the various interventions with one another and so cannot comment on the superiority of one intervention over another. Complications were reported more often with use of opioids.

Isoflurane and sevoflurane decrease entropy indices more than halothane at equal MAC values

Recently, bispectral index (BIS) values were demonstrated to be different for various anesthetics as a result of differential effects on electroencephalographic (EEG) signals. Entropy is similar to the BIS monitor, as both process raw EEG to derive a number. We hypothesized that entropy may also be anesthetic agent-specific. Thirty adult patients undergoing spinal surgery were randomized to receive halothane, isoflurane, or sevoflurane. Entropy indices were recorded at various minimum alveolar concentration (MAC) values—0.5, 0.75, 1.0 and 1.5—both during wash-in and wash-out of the agent. Heart rate (HR), mean arterial blood pressure (MAP), response entropy (RE), and state entropy (SE) were noted. Statistical analysis was done using a one-way analysis-ofvariance test. P values less than 0.05 were considered significant. Ten patients in each group completed the study. The demographics and baseline values of HR, MAP, RE, and SE were comparable in all three groups. During the study period, for a given MAC value, both RE and SE remained low in the isoflurane and sevoflurane groups compared to the halothane group. For a given MAC, the RE and SE were comparable during wash-in and wash-out phases. Halothane produced higher entropy values as compared to isoflurane and sevoflurane at equivalent MAC levels.

Asystole may be the most severe sequela of the trigeminocardiac reflex: a comment on "Asystole due to trigemino-cardiac reflex: A rare complication of trans-sphenoidal surgery for pituitary adenoma".

Dear Professor Kaye, We read with interest the recently published report by Seker et al. that demonstrates the occurrence of the trigemino-cardiac reflex (TCR) resulting in asystole in a patient undergoing transsphenoidal (TS) surgery for pituitary adenoma. As mentioned by the authors, this reflex may be elicited during any stage of TS surgery. We wish to state that although the occurrence of asystole due to the TCR has never been reported during TS surgery, this complication is not entirely new, as far as the TCR is concerned. Stimulation of the trigeminal nerve anywhere along its course may result in elicitation of this reflex. At times, the stimulation may be severe enough to produce asystole as demonstrated in our report where this complication occurred during skin flap elevation. Asystole could be considered as one of the most severe sequelae of the TCR. Cessation of the surgical stimulus and administration of atropine are recommended treatments for the TCR. However, this may not hold true in every patient, as demonstrated in our report. At times the TCR may not respond to atropine administration, and anesthesiologists may have to administer pressor agents to maintain haemodynamics. The TCR in such situations may be refractory to conventional treatment. TCR is now a well-recognized entity seen during cranial and maxillofacial surgery. We agree with the authors that the literature does not identify TCR as a possible complication of TS surgery. However, with growing evidence of

Acromegalic and "Mallampati class zero" airway--an unusual finding!

To the JNA Readership: Acromegaly is a recognized cause of difficult intubation and airway management. The incidence of difficult intubation in patients with acromegaly is about 4 to 5 times higher than the rates of about 2.5% in those without acromegaly. Mallampati grades are popularly used to predict difficult intubation. Ezri et al suggested a new class 0 (zero) to the existing scoring system. They suggested that a visible epiglottis on mouth opening is an excellent predictor of grade I laryngoscopy. There have been more such reports of class 0 in normal population, but none reported so far in acromegalics. Recently, we confirmed this observation of Ezri et al when a 35-year-old male acromegalic was scheduled to undergo transsphenoidal pituitary surgery for the removal of pituitary tumor. His acromegalic features included typical large facies, with a large mandible, and a thyromental distance of 14 cm. Upper lip bite test introduced by Khan and colleagues is a simple single test for predicting difficult intubation. The upper lip bite test performed by the patient revealed class 3, predicting difficult intubation. However, his preoperative airway assessment revealed a visible epiglottis both in sitting and supine position (Fig. 1). The patient was reluctant to undergo awake fibreoptic tracheal intubation and refused consent. Under general anesthesia, presence of beard and large mandible initially resulted in difficult mask ventilation but was possible as the anesthesiologist held the mandibles with both hands and the assistant manually ventilated the patient. Interestingly, the laryngoscopic view was grade I. This case shows that class 0 may occur even in acromegalics who are otherwise believed to be a difficult airway group. It also suggests that class 0 may definitely be associated with easy tracheal intubation, as also reported and confirmed by previous authors. Whether the new class should be added to the existing scoring system of airway assessment needs further evaluation.

Pontine infarct during deep brain stimulation surgery as the cause of postoperative hemiparesis

Address for correspondence: Dr. Zulfiqar Ali, Department of Neuroanaesthesiology, Sheri Kashmir Institute of Medical Sciences, Srinagar 190 010, Jammu and Kashmir, India. E-mail: zulfiqaraliiii@yahoo.com electrodes were being placed on the right side, the patient was suddenly uncooperative. He stopped following commands from the neurologist and became restless. The procedure was abandoned and patient was shifted for computed tomography (CT) of head. The scan revealed a large pneumocephalus but no operative site haematoma or any other abnormality [Figure 1a].

Valsalva's maneuver to assist delivery of a neurocysticercosis cyst from the fourth ventricle.

To the Editor: Valsalva’s Maneuver (VM) may be employed in patients undergoing intracranial surgery to confirm venous hemostasis and facilitate tumor resection during transsphenoidal pituitary surgery. We used this technique to help deliver a neurocysticercosis cyst from the fourth ventricle of the brain in a 15-yr-old boy. Under general endotracheal anesthesia, the fourth ventricle was opened. VMs were performed three times to maintain airway pressure of 20 cm H2O greater than the peak airway pressure for 10–15 s. The cyst began to bulge out and after the fourth VM, 3/4th of the cyst was out but the surgeon was not able to grasp it. The surgeon passed a catheter over the cyst to reach behind and gently irrigated with saline to release the adhesions. The combination of VM and irrigation helped deliver the cyst complete. Studies show that VM increases intrathoracic pressure, which may significantly alter systemic and cerebral circulation. Wendling et al. and Prabhakar et al. demonstrated an increase in intracranial pressure following VM in anesthetized neurosurgical patients. In our case, application of VM resulted in extrusion of the intracranial contents through the dural defect, facilitating the delivery of the fourth ventricular cyst. Hemanshu Prabhakar, MD