Neus Fàbregas

Can bispectral index monitoring predict recovery of consciousness in patients with severe brain injury

Background:The probability of recovering consciousness in acute brain-injured patients depends on central nervous system damage and complications acquired during their stay in the intensive care unit. The objective of this study was to establish a relation between the Bispectral Index (BIS) and other variables derived from the analysis of the electroencephalographic signal, with the probability of recovering consciousness in patients in a coma state due to severe cerebral damage. Methods:Twenty-five critically ill, unconscious brain-injured patients from whom sedative drugs were withdrawn at least 24 h before BIS recording were prospectively studied. BIS, 95% spectral edge frequency, burst suppression ratio, and frontal electromyography were recorded for 20 min. The neurologic condition of the patients was measured according to the Glasgow Coma Score (GCS). Patients were followed up for assessment of recovery of consciousness for 6 months after the injury. The studied variables were compared between the group of patients who recovered consciousness and those who did not recover. Their predictive ability was evaluated by means of the Pk statistic. Univariate and multivariate logistic regression was used to model the relation between variables and probability of recovery of consciousness. Cross-validation was used to validate the proposed model. Results:There were statistically significant differences between the group of patients who recovered consciousness and those who did not with respect to BISmax, BISmin, BISmean, and BISrange, frontal electromyography, signal quality index values, and GCSBIS. The Pk (SE) values were 0.99 (0.01) for electromyelography, 0.96 (0.05) for BISmax, 0.92 (0.05) for BISmean, 0.92 (0.06) for BISrange, and 0.82 (0.09) for GCSBIS. The odds ratio for BISmax in the logistic regression model was 1.17 (95% confidence interval, 1.1–1.35). Cross-validation results reported a high-accuracy median absolute cross-validation performance error of 3.06% (95% confidence interval, 1–22.15%) and a low-bias median cross-validation performance error of 0.84% (0.56–2.12%). Conclusions:The study of BIS and other electrophysiologic and clinical variables has enabled construction and cross-validation of a model relating BISmax to the probability of recovery of consciousness in patients in a coma state due to a severe brain injury, after sedation has been withdrawn.

Sampling methods for ventilator-associated pneumonia: validation using different histologic and microbiological references.

ObjectiveTo validate sampling techniques (tracheobronchial aspirates, protected specimen brush, and bronchoalveolar lavage, both conventional and protected) for the detection of ventilator-associated pneumonia (VAP) and causative microorganisms according to different histologic and microbiological references. DesignImmediate, multiple bilateral lung biopsy, postmortem study. SettingRespiratory intensive care unit of a 1,000-bed teaching hospital. PatientsTwenty-five mechanically ventilated patients (>72 hrs) who died in our intensive care unit. MeasurementsLung tissue histologic examination and quantitative cultures (16 specimens/patient). The following four references for the diagnostic techniques were used: histology of guided lung biopsy, histology of blind lung biopsy, combined guided and blind lung biopsy histology and microbiology of lung tissue, and microbiology of lung tissue. ResultsSensitivities when histologic reference tests were used ranged from 16% to almost 40%, whereas specificity rates were always <80%. When we combined both lung histology of guided or blind specimens and microbiology of lung tissue, all diagnostic techniques achieved considerably higher but still limited diagnostic yields (sensitivity range 43% to 83%; specificity range 67% to 91%). Causative organisms were missed in a significant number of cases by all techniques (17% to 83%). ConclusionsThe diagnostic performances of different diagnostic techniques strongly depend on the reference used. All techniques for detecting VAP are of limited value. Finding a balance between clinical judgment and microbiological results is crucial to appropriately manage patients with VAP.

Anesthetic management of surgical neuroendoscopies: usefulness of monitoring the pressure inside the neuroendoscope.

Neuroendoscopic procedures are increasing in frequency in neurosurgical practice. We describe the anesthetic technique and the perioperative complications found in 100 neuroendoscopic interventions performed at our institution. Cranial tumor biopsy or retrieval (62%) and cisternostomy for hydrocephalus (33%) were the most frequent indications for neuroendoscopy. The mortality rate was low (1%). Intraoperative complications occurred in 36 patients, with arterial hypertension being the most frequent (53%). Postoperative complications occurred in 52 patients; anisocoria (31%) and delayed arousal (29%) were the most frequent. The pressure inside the endoscope was monitored intraoperatively in the last 47 patients. A saline-filled catheter from a pressure transducer connected to the neuroendoscopy system was used for pressure monitoring. We recorded the highest peak of pressure values measured during each procedure. Twenty-three patients (49%) had peak pressure values >30 mm Hg, 12 patients (25%) >50 mm Hg, and 3 patients >100 mm Hg. Only one patient had hemodynamic changes occurring simultaneously with the pressure changes. We found an association between pressure inside the endoscope >30 mm Hg and postoperative (P = .003) but not intraoperative complications. A relationship was found between surgical duration and postoperative complications (P = .002). Neither the pressure inside the endoscope or the intraoperative morbidity were related to surgical duration. We conclude that there may be a high rate of postoperative complications after neuroendoscopies, namely, new neurologic deficits. High pressure levels inside the endoscope during neuroendoscopic procedures can occur without hemodynamic warning signs. Pressure values >30 mm Hg are associated with postoperative morbidity, especially unexpected delayed recovery. Measuring the pressure inside the endoscope is technically easy and might be beneficial if performed in all neuroendoscopic procedures. Reducing the incidence of episodes of high peak pressure values might decrease the rate of postoperative complications.

Combination of diffusion tensor and functional magnetic resonance imaging during recovery from the vegetative state

BackgroundThe rate of recovery from the vegetative state (VS) is low. Currently, little is known of the mechanisms and cerebral changes that accompany those relatively rare cases of good recovery. Here, we combined functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) to study the evolution of one VS patient at one month post-ictus and again twelve months later when he had recovered consciousness.MethodsfMRI was used to investigate cortical responses to passive language stimulation as well as task-induced deactivations related to the default-mode network. DTI was used to assess the integrity of the global white matter and the arcuate fasciculus. We also performed a neuropsychological assessment at the time of the second MRI examination in order to characterize the profile of cognitive deficits.ResultsfMRI analysis revealed anatomically appropriate activation to speech in both the first and the second scans but a reduced pattern of task-induced deactivations in the first scan. In the second scan, following the recovery of consciousness, this pattern became more similar to that classically described for the default-mode network. DTI analysis revealed relative preservation of the arcuate fasciculus and of the global normal-appearing white matter at both time points. The neuropsychological assessment revealed recovery of receptive linguistic functioning by 12-months post-ictus.ConclusionsThese results suggest that the combination of different structural and functional imaging modalities may provide a powerful means for assessing the mechanisms involved in the recovery from the VS.

Modeling of the Sedative and Airway Obstruction Effects of Propofol in Patients with Parkinson Disease undergoing Stereotactic Surgery

Background Functional stereotactic surgery requires careful titration of sedation since patients with Parkinson disease need to be rapidly awakened for testing. This study reports a population pharmacodynamic model of propofol sedation and airway obstruction in the Parkinson disease population. Methods Twenty-one patients with advanced Parkinson disease undergoing functional stereotactic surgery were included in the study and received propofol via target-controlled infusion to achieve an initial steady state concentration of 1 &mgr;g/ml. Sedation was measured using the Ramsay Sedation Scale. Airway obstruction was measured using a four-category score. Blood samples were drawn for propofol measurement. Individual pharmacokinetic profiles were constructed nonparametrically using linear interpolation. Time course of sedation and respiratory effects were described with population pharmacodynamic models using NONMEM. The probability (P) of a given level of sedation or airway obstruction was related to the estimated effect-site concentration of propofol (Ce) using a logistic regression model. Results The concentrations predicted by the target-controlled infusion system generally exceeded the measured concentrations. The estimates of C50 for Ramsay scores 3, 4, and 5 were 0.1, 1.02, and 2.28 &mgr;g/ml, respectively. For airway obstruction scores 2 and 3, the estimates of C50 were 0.32 and 2.98 &mgr;g/ml, respectively. Estimates of ke0 were 0.24 and 0.5 1/min for the sedation and respiratory effects, respectively. Conclusions The pharmacokinetic behavior of propofol in patients with Parkinson disease differs with respect to the population from which the model used by the target-controlled infusion device was developed. Based on the results from the final models, a typical steady state plasma propofol concentration of 0.35 &mgr;g/ml eliciting a sedation score of 3 with only minimal, if any, airway obstruction has been defined as the therapeutic target.

Intraoperative warming and post-operative cognitive dysfunction after total knee replacement

Background: Post‐operative cognitive dysfunction (POCD) can affect 30% of orthopedic surgery patients. We hypothesized that perioperative temperature has an impact on POCD.

Anaesthetic and ICU management of aneurysmal subarachnoid haemorrhage: a survey of European practice.

BACKGROUND Many aspects of the perioperative management of aneurysmal subarachnoid haemorrhage (SAH) remain controversial. It would be useful to assess differences in the treatment of SAH in Europe to identify areas for improvement. OBJECTIVE To determine the clinical practice of physicians treating SAH and to evaluate any discrepancy between practice and published evidence. DESIGN An electronic survey. PARTICIPANTS Physicians identified through each national society of neuroanaesthesiology and neurocritical care. INTERVENTIONS A 31-item online questionnaire was distributed by the ENIG group. Questions were designed to investigate anaesthetic management of SAH and diagnostic and treatment approaches to cerebral vasospasm. The survey was available from early October to the end of November 2012. RESULTS Completed surveys were received from 268 respondents, of whom 81% replied that aneurysm treatment was conducted early (within 24 h). Sixty-five percent of centres treated more than 60% of SAH by coiling, 19% had high-volume clipping (>60% of aneurysms clipped) and 16% used both methods equally. No clear threshold for arterial blood pressure target was identified during coiling, temporary clipping or in patients without vasospasm after the aneurysm had been secured. Almost all respondents used nimodipine (97%); 21% also used statins and 20% used magnesium for prevention of vasospasm. A quarter of respondents used intra-arterial vasodilators alone, 5% used cerebral angioplasty alone and 48% used both endovascular methods to treat symptomatic vasospasm. In high-volume clipping treatment centres, 58% of respondents used endovascular methods to manage vasospasm compared with 86% at high-volume coiling treatment centres (P < 0.001). The most commonly used intra-arterial vasodilator was nimodipine (82%), but milrinone was used by 23% and papaverine by 19%. More respondents (44%) selected ‘triple-H’ therapy over hypertension alone (30%) to treat vasospasm. CONCLUSION We found striking variability in the practice patterns of European physicians involved in early treatment of SAH. Significant differences were noted among countries and between high and low-volume coiling centres.

Craniotomy in sitting position: anesthesiology management.

Purpose of review Sitting position to surgically approach posterior fossa disorder continues to be the first choice for some neurosurgical teams. We underwent a literature research for recent published studies involving neurosurgical patients operated on in this position. Preoperative evaluation, anesthetic technique, intraoperative monitoring, detection and treatment of venous or arterial air embolism episodes, and all the reported complications were recorded. Recent findings A modified semisitting (lounging) position aiming to create a positive pressure in the transverse and sigmoid sinuses, with lower head and higher legs positioned above the top of the head, decreases the incidence and severity of venous air embolism. Hyperventilation, compromising cerebral blood flow, has to be avoided during a sitting position. Precordial Doppler or transesophageal echocardiography monitoring improves the detection of small venous air embolism enabling its early treatment and diminishing its consequences. Patients with known patent foramen ovale can be operated on in a sitting position, under strict protocol, with few reported clinical venous air embolism and no paradoxical air embolism. Summary Sitting position for neurosurgical procedures may be a well tolerated approach for the patient if neurosurgeons and neuroanesthesiologists undergo a strict team protocol, including all necessary monitoring and meticulously followed.

Teaching basic life support algorithms by either multimedia presentations or case based discussion equally improves the level of cognitive skills of undergraduate medical students

Background: There is no evidence on the best method for teaching Basic Life Support (BLS). Aims: To compare two methods for teaching BLS, assessing the level of cognitive skills. Methods: Randomized, prospective study including 68 medical students. BLS algorithms were taught for 60 minutes using either a multimedia presentation (Group I, n = 34) or case based discussion (Group II, n = 34). Assessments included a scenario-based quiz test and an error-pinpointing video, which the students completed before (T1) and after (T2) teaching. Comparisons between both groups were made on scores of the assessments, actual increases in scores (final value–initial value) and score gains (actual increase/potential increase). Results: No significant differences were found between the groups in any of the recorded scores. Both groups improved their T2 scores (p values <0.001). The actual increases in scores and the score gains were similar in both groups. Test scores improved in 55.9% of students in Group I and 58.8% in Group II; video scores improved in 85.3% of Group I and in 82.3% of Group II. Conclusions: BLS teaching by either multimedia presentations or case based discussion equally improves the level of cognitive skills among medical students.

Endoscopic and stereotactic neurosurgery

Purpose of review Review of the anesthetic considerations for neuroendoscopy and stereotactic procedures. Recent findings Minimally invasive procedures are increasingly applied in novel ways in the diagnosis and treatment of neurological pathologies. Endoscopic third ventriculostomy, endoscopic shunt revisions and drainage of intraventricular hematoma using a neuroendoscope have become routine neurosurgical procedures. Stereotaxis has expanded its scope from simple brain biopsy to functional neurosurgery and psychiatry. While these procedures are ‘minimally invasive’, perioperative critical events may still occur. Summary Vigilance in preoperative assessment and intraoperative monitoring is essential in minimizing perioperative morbidity and mortality in patients undergoing neuroendoscopic and stereotactic procedures.