Haemodynamic changes during prone positioning in anaesthetised chronic cervical myelopathy patients.

BACKGROUND AND AIMS: Anaesthetised patients, when positioned prone, experience hypotension and reduction in cardiac output. Associated autonomic dysfunction in cervical myelopathy patients predisposes them to haemodynamic changes. The combined effect of prone positioning and autonomic dysfunction in anaesthetised patients remains unknown. METHODS: Thirty adult chronic cervical myelopathy patients, aged 18-65 years with Nurick grade ≥2 were recruited in this prospective observational study. Heart rate, mean blood pressure, cardiac output, stroke volume, total peripheral resistance and stroke volume variation were measured using NICOM® monitor. Data were collected in supine before anaesthetic induction (baseline), 2 minutes after induction, 2 minutes after intubation, before and after prone positioning and every 5 minutes thereafter until skin incision. Repeated measures analysis of variance (ANOVA) was used to analyse the haemodynamic parameters across the time points. Bivariate Spearman's correlation was used to find factors associated with blood pressure changes. A P value <0.05 was kept significant. RESULTS: Cardiac output during the entire study period remained stable (P = 0.186). Sixty percent of the patients experienced hypotension. At 15 and 20 minutes after prone positioning, mean blood pressure decreased (P = 0.001), stroke volume increased (P = 0.001), and heart rate and total peripheral resistance decreased (P < 0.001, P = 0.001, respectively). These changes were significant when compared to pre-prone position values. Number of levels of spinal cord compression positively correlated with the incidence of hypotension. CONCLUSION: Cervical myelopathy patients experienced hypotension with preserved cardiac output in prone position due to a reduction in total peripheral resistance. Hypotension correlated with the number of levels of spinal cord compression.

Airway management in the presence of cervical spine instability: A cross-sectional survey of the members of the Indian Society of Neuroanaesthesiology and Critical Care.

BACKGROUND AND AIMS: There is a paucity of clinical practice guidelines for the ideal approach to airway management in patients with cervical spine instability (CSI). The aim of this survey was to evaluate preferences, perceptions and practices regarding airway management in patients with CSI among neuroanaesthesiologists practicing in India. METHODS: A 25-item questionnaire was circulated for cross-sectional survey to 378 members of the Indian Society of Neuroanaesthesiology and Critical Care (ISNACC) by E-mail. We sent four reminders and again submitted our survey to non-responders during the 2017 annual ISNACC meeting. Apart from demographic information, the survey captured preferred methods of intubation and airway management for patients with CSI and their justification. Regression analysis was used to identify factors associated with the use of indirect technique for intubation. RESULTS: Only 122 out of the 378 anaesthesiologists responded to our survey. Most respondents were senior consultants, working in training hospitals, and performed ≥25 intubations per year for CSI patients. The majority of neuroanaesthesiologists (78.7%; n = 96) preferred indirect techniques for elective intubation. However, 45 anaesthesiologists (36.9%) preferred indirect techniques for emergency intubation. In an adjusted analysis, preference for patients to be conscious during intubation was significantly associated with the use of indirect techniques (odds ratio = 3.79; confidence interval = 1.52-9.49, P < 0.01). CONCLUSIONS: Among ISNACC members, indirect techniques are preferred for elective intubation of patients with CSI, while direct laryngoscopy is preferred for emergency intubation.

Ventilatory Management During Intraoperative Airway Obstruction due to Endotracheal Tube Kinking.

We present a case of polyvinyl chloride (PVC) endotracheal (ET) tube kinking and discuss the airway pressure changes, implications, and ventilation-based methods to functionally remedy the situation. The kink developed in the intraoral portion of an 8.5-cm PVC ET tube in a patient undergoing T3-T5 laminectomy in the prone position, heralded by a sudden increase in peak airway pressure. The kink was confirmed by attempted intratubal suction. Adequate ventilation was achieved with conversion to pressure control (PC) mode with an inspiratory-expiratory time (I:E) ratio of 1:1. An experiment was conducted using 8.5-cm PVC ET tube, ventilating a 2-L reservoir bag. A kink was artificially created on the ET tube and ventilated with volume control (VC) and then PC mode. Both modes delivered equal tidal volumes at equal plateau pressures, with higher peak pressures in VC mode. The PC mode with I:E 1:1 delivered higher tidal volume than I:E 1:2 and 2:1 at equal plateau pressures. Whereas previous reports of intraoperative ET tube kinking discussed the detection, diagnosis, cause, and management in scenarios where the tube is readily accessible, we highlight airway pressure characteristics and ventilator management of such a situation when an ET tube was not amenable to remedial solutions.

Paroxysmal sympathetic hyperactivity in severe traumatic brain injury.

BACKGROUND: Paroxysmal sympathetic hyperactivity (PSH) is a less-known complication of traumatic brain injury (TBI). This study was done to assess the clinical features and outcome of patients who develop PSH following severe TBI. METHODS: A prospective observational study was done on patients, admitted in the intensive care unit, for treatment of severe TBI. The clinical characteristics and outcome of patients, with and without PSH, was compared. At the time of discharge, patients were assessed with the Disability Rating Scale (DRS), and at 6 months with the Glasgow Outcome Score Extended (GOSE). RESULTS: The incidence of PSH was 8 % (29/343). Tachycardia, hypertension, and sweating were seen in all of the patients. Tachypnea was seen in 24 (82.8 %), hyperthermia in 28 (96.6 %), and posturing in 13 (44.8 %) patients. Thirteen (44.8 %) patients had all six symptoms of PSH. Follow-up data were available for 23 (79.3 %) patients. At the end of 6 months, 14 (60.9 %) patients had died, seven (30.4 %) were severely disabled, and two (8.7 %) were moderately disabled. There was a significant correlation of GOSE with the number of symptoms of PSH (Spearman's rho = 0.502, p = 0.015). The patients with PSH had significantly higher DRS scores at discharge, 25.3 vs. 19.9, p < 0.001; higher mortality at 6 months 60.9 vs. 30.4 %, p < 0.001; and higher proportions with unfavorable outcome. CONCLUSIONS: Presence of PSH in patients with severe TBI was associated with prolonged hospital stay, poorer DRS at discharge, more deaths, and unfavorable outcome. The number of symptoms of PSH had a significant effect on outcome at 6 months.

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.

Endovascular coil detachment causing EMG artefact in BIS: a mechanistic exploration.

Deployment of endovascular coils used in interventional neuroradiology commonly involves electrolytic detachment of the coil from the pusher catheter. This report describes a case of artefactual increase in electromyography (EMG) values of bispectral index (BIS) monitor during coil detachment. An explanation of this event is provided connecting mechanism of coil detachment and derivation of EMG values in a BIS monitor. While rising EMG values are thought to arise from frontalis contraction, they may as well be an unrecognized electrical artefact, especially in context of undistorted electroencephalography waveform.

Fentanyl co-administration decreases the induction dose requirement of propofol in patients with supratentorial tumors and not in patients with spinal lesions.

BACKGROUND: The requirement of anesthetic drugs in a patient with an intracranial space-occupying lesion is of relevance to the neuroanesthetist. The requirement is often presumed to have reduced or at least altered. However, not much research has focused on this issue. Hence, we conducted this study to examine whether intracranial tumors reduce the induction dose of propofol in patients undergoing craniotomy based on plasma and effect site concentrations (Ce) of propofol and the effect of additional fentanyl. METHODS: A total of 80 patients were recruited into the study. The study group included patients with supratentorial tumors undergoing craniotomy, and the control group consisted of patients undergoing spinal surgeries. Patients in each group were randomized further to receive propofol alone or propofol preceded by fentanyl for induction of anesthesia. They were divided into the following groups: patients with supratentorial tumor receiving only propofol (group T1), or fentanyl and propofol (group T2); patients who were undergoing spinal surgery and receiving only propofol (group S1) or fentanyl and propofol (group S2). Anesthesia was induced with infusion of propofol through a Target Controlled Infusion pump. At the point of loss of verbal contact, plasma concentration (Cp) and Ce of propofol, time taken for loss of consciousness, and the total dose of propofol required were noted. Hemodynamic variables were recorded before and after induction of anesthesia. RESULTS: There were 19, 21, 19, and 21 patients in groups TI, T2, S1, and S2, respectively. In group T2 the Cp, Ce, time to loss of verbal contact, and dose required for induction were all significantly lower compared with the other groups. There were no significant differences in the study parameters between T1 and S1, whereas the differences were significant between T2 and S2 (Cp: 3.9±1.1 vs. 4.9±1.2 µg/mL; Ce: 2.6±1.0 vs. 3.7±1.2 µg/mL; P<0.05). CONCLUSIONS: Propofol dose for induction of anesthesia was significantly reduced when administered after fentanyl in patients with supratentorial tumors. Tumors per se without fentanyl coadministration do not decrease the propofol requirement for induction of anesthesia.

Effect of a course of electroconvulsive therapy on interictal bispectral index values: a prospective study.

OBJECTIVES: Bispectral index (BIS) value measures the level of hypnosis (sedation) during anesthesia. It uses electroencephalographic signals to measure the level of sedation. Electroconvulsive therapy (ECT)-induced changes in electroencephalography last for several hours to days. How this affects BIS values is unknown. METHODS: In 30 patients with schizophrenia or mood disorders who were prescribed ECT (bitemporal, brief-pulse ECT), BIS values were obtained before the start of anesthesia on the first (baseline), fourth (48 hours after the third ECT), and seventh ECT (48 hours after the sixth ECT) sessions. Bispectral index values were recorded in resting state and during a short conversation a few minutes before the induction of anesthesia. The changes in BIS values through the course of ECT were analyzed using repeated-measures analysis of variance and the McNemar test. RESULTS: Mean (SD) resting BIS value dropped from 91.6 (6.6) at baseline to 79.7 (20.2) after the sixth ECT (repeated-measures analysis of variance occasion effect: F = 6.78; df = 2,58; P = 0.02). The drop in corresponding values during conversation was not significant. The proportion of patients whose resting BIS values were in the sedated/anesthetized range increased from 26% at baseline to 60% after the sixth ECT session (McNemar test: P = 0.031). CONCLUSIONS: Bispectral index values of awake individuals in resting state drop significantly through a course of bitemporal brief-pulse ECT. Anesthesiologists should be aware that a considerable proportion of patients who have received a course of ECT may have BIS values in the sedated/anesthetized range even when they are awake. The BIS may not provide accurate estimation of the depth of anesthesia during ECT after the initial ECT sessions.

Predictive model for survival among neurosurgical intensive care patients.

BACKGROUND: Models for prediction of outcome of intensive care patients greatly help the physician to make decisions and are also important for risk stratification in clinical research and quality improvement. At present, there are no major predictive models for neurosurgical intensive care unit (NSICU) patients. This study aimed to develop a predictive model for survival in NSICU patients. METHODS: This is a prospective observational study in the NSICU at a tertiary-care university hospital. The data were collected within 24 hours of admission in all patients admitted to the NSICU. The parameters collected were demographic variables, systolic blood pressure, arterial oxygen tension after resuscitation (PaO2), Glasgow coma score (GCS) and pupillary signs, blood urea, creatinine, albumin, glucose, sodium, potassium, serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, alkaline phosphatase, bilirubin, hemoglobin concentration, leukocyte count, platelet count, temperature, and evidence of infection. Mortality or discharge from NSICU was the primary outcome variable. All patients were provided full care until death or discharge from the ICU. Life support was not withdrawn in any of the patient based on the perception of outcome by the treating physician. All variables were compared between survivors and nonsurvivors. Significant variables were analyzed by multivariate logistic regression and a prediction model was developed. RESULTS: Four hundred six patients were included in the study. Three hundred two patients survived and 104 died (mortality of 25.6%). Significant variables on univariate analysis include primary reason for admission, GCS, pupillary reaction, systolic blood pressure, serum albumin, glucose, serum sodium concentration, hypothermia, and infection at the time of admission. Multivariate analysis showed that the significant independent factors for predicting outcome in NSICU patients are age, diagnosis, GCS, pupillary status, albumin, and serum sodium concentration. The predictive model has good discrimination (receiver operating characteristic curve=0.796) and good calibration (P=0.937). The overall accuracy of the model was 81%. CONCLUSIONS: In the current model of prediction of survival in a neurosurgical ICU, age, diagnosis, GCS, pupillary status, serum albumin, and serum sodium are independent predictors of survival in NSICU patients.

Pulmonary function after surgery for congenital atlantoaxial dislocation: a comparison with surgery for compressive cervical myelopathy and craniotomy.

Deterioration of pulmonary function after surgery for congenital atlantoaxial dislocation (AAD) has been documented in a few studies. We proposed that this deterioration in AAD is much higher than what can be expected after a surgical procedure under general anesthesia or what occurs after any surgery on the cervical spine. To test this hypothesis, we recorded forced vital capacity (FVC), forced expiratory ratio (FEV 1.0), forced expiratory flow (FEF 25%-75%) and muscle power in the extremities in 25 patients undergoing surgical correction of AAD (AAD group), 29 patients undergoing surgery for compressive cervical spine lesions (cervical spine group) and 20 patients undergoing craniotomy for an intracranial lesion (craniotomy group). The observations were made before surgery and on postoperative days 1 and 7. The demographic characters were comparable among the 3 groups. All patients underwent an uneventful surgery and their trachea was extubated in the operating room. There was no decrease in the muscle power in the postoperative period in any of the groups. A significant decrease in FVC (expressed as percentage of the predicted value) was seen postoperatively in all the 3 groups. The reduction of FVC was significantly different among the groups, with the AAD group having the lowest values (P<0.001). The FVC values in the AAD group were 74.6+/-19.6%, 49.6+/-17.7%, 64.0+/-20.8% at baseline, on postoperative days 1 and 7, respectively (P<0.001). Postoperative change in forced expiratory ratio was also significantly different among the groups (P=0.03). A significant difference was found between the AAD and cervical spine group (89.8+/-8.3%, 88.2+/-17.6%, 89.3+/-9.8% in the AAD group and 95.5+/-20.5%, 78.4+/-13.4%, 72.7+/-19.1% in the cervical spine group at baseline and on postoperative days 1 and 7, respectively, P<0.05). FEF 25%-75% changes were also significantly different among the groups (P<0.001). The decrease in the AAD and cervical spine groups was significantly higher than that in the craniotomy group (P<0.001). In conclusion, during the first week after surgery, deterioration of pulmonary function in the AAD group is significantly different from that seen in patients undergoing surgery for compressive cervical lesions or craniotomy for a cerebral lesion. The data imply the need for special attention to respiratory function in patients operated for AAD in the postoperative period.

Quantification of burst suppression and bispectral index with 2 different bolus doses of thiopentone sodium.

Metabolic suppression caused by barbiturates is a major mechanism responsible for their cerebral protective potential. Maximal cerebral metabolic suppression is believed to coincide with electroencephalographic burst suppression. However, many neurosurgical procedures associated with cerebral ischemic threat are still performed in the absence of electroencephalogram monitoring, especially in developing nations. The present study was designed to assess the degree of burst suppression with 2 different doses of thiopentone sodium administered on the background of isoflurane anesthesia intraoperatively. Forty-one patients without any intracranial pathology undergoing elective spinal surgery under a general anesthetic consisting of N2O (60%) in O2 (40%) and isoflurane to maintain a bispectral index (BIS) value of 45 were randomized to receive a thiopentone bolus of either 3 or 5 mg/kg. BIS, burst suppression ratio (BSR), systolic blood pressure, and heart rate were recorded before the bolus and every 15 seconds for first 2 minutes and every 30 seconds for another 8 minutes. During the 10-minute study period after the administration of thiopentone bolus, BIS values were significantly lower in the group that received thiopentone 5 mg/kg compared with the group that received thiopentone 3 mg/kg (P<0.02). BSR>25% was seen in 7 out of 21 patients in the 3 mg/kg group and 10 out of 20 patients in the 5 mg/kg group. There was a statistically insignificant prolongation of the duration of burst suppression with thiopentone 5 mg/kg [243 s (range 75 to 435 s)] compared with thiopentone 3 mg/kg [171 s (30 to 465 s)]. The number of patients who had a BSR >50% was higher among patients who received thiopentone 5 mg/kg as compared with those who received a dose of 3 mg/kg [9/20 vs. 3/21(P<0.02)]. We conclude that thiopentone in a bolus dose of 3 to 5 mg/kg produces only a short duration of incomplete burst suppression. Also, in this dose range, burst suppression does not occur consistently in all patients. The present data suggest that bolus doses of thiopentone in the range of 3 to 5 mg/kg may have very limited value in providing significant metabolic suppression required for intraoperative cerebral protection during temporary ischemic episodes.