Enrique Carrero

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 Methods:Twenty-five critically ill, unconscious brain-injured patients from whom sedative drugs were withdrawn at least 24 h before BIS recording were prospectively studied.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.

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.

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.

Unilateral trigeminal and facial nerve palsies associated with epidural analgesia in labour

Purpose To report a rare complication related to epidural analgesia for obstetrics: the association of unilateral trigeminal and facial nerve palsies in a patient with the clinical syndrome of intracranial hypotension.Clinical featuresA 38-yr-old woman was admitted in pre-term labour (at 35 wk gestation). She was receiving 40 mg methadonepo daily for opioid addiction. Epidural analgesia for labour was established with 9 ml bupivacaine 0.25%. The patient underwent normal vaginal delivery of a 2500 g female infant. She developed post-dural puncture headache (PDPH) on the third postpartum day which was managed by palliative measures: bed rest (patient’s position of choice), increased hydration (water: 3 litrespo per day), lysine acetyl salicylate (5.4 gpo per day) and caffeine (600 mgpo per day). She developed paraesthesiae and numbness of the right side of the face one day after the onset of PDPH and unilateral facial nerve palsy two days later. There was no evidence of durai puncture and no cause was found. Treatment of the nerve palsies with epidural blood patch or epidural dextran 40 was not considered to be indicated. Headache disappeared on the 10th postpartum day and trigeminal palsy regressed. At the time of discharge, on the 17th postpartum day, neurological examination showed minimal facial assimetry. The patient refused further exploration and follow-up.ConclusionPost delivery trigeminal and facial nerve palsy in a 38 yr old woman recovered spontaneously with conservative therapy.RésuméObjectifRapporter une complication rare liée à l’analgésie péridurale obstétricale: l’association de paralysie unilatérale du nerf trijumeau et du nerf facial chez une patiente qui présentait le syndrome d’hypotension intracranienne.Aspects cliniquesUne femme de 38 ans, en travail prématuré, a été admise à l’hôpital à 35 semaines de grossesse. Elle recevait quotidiennement 40 mg de méthadonepo pour contrer une dépendance aux opioïdes. L’analgésie péridurale pour le travail a été induite avec 9 ml de bupivacaïne 0,25 %. La patiente a accouché normalement par voie vaginale et a donné naissance à une fille de 2 500 g. Elle a présenté, le troisième jour du postpartum, une céphalée post-ponction durale (CPPD) qui a été traitée par des mesures palliatives: repos au lit (position préférée de la patiente), hydratation accrue (eau: 3 litrespo par jour), lysine salicylate d’acétyle (5,4 gpo par jour) et caféine (600 mgpo par jour). Elle a éprouvé une paresthésie et des engourdissements du côté droit du visage le jour suivant le début de la CPPD et, deux jours plus tard, une paralysie unilatérale du nerf facial. Il n’y avait pas d’évidence de ponction de la dure-mère et aucune cause n’a été identifiée. On n’a pas jugé que le traitement de la paralysie des nerfs au moyen d’un bloodpatch péridural ou de dextran 40 péridural était indiqué. La céphalée a disparu au 10e jour postpartum et la paralysie du trijumeau a aussi régressé. Au moment du congé, le 17e jour postpartum, l’examen neurologique démontrait une asymétrie faciale minimale. La patiente a refusé tout examen supplémentaire et toute relance.ConclusionUne femme de 38 ans a récupéré spontanément d’une paralysie trigémiale et faciale postpartum après une thérapie conservatrice.

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.

Pressure inside the neuroendoscope: correlation with epidural intracranial pressure during neuroendoscopic procedures.

Background During neuroendoscopic procedures, pressure inside the neuroendoscope (PIN) monitored through the irrigation channel correlates with the occurrence of postoperative complications. Our aim was to analyze the reliability of PIN measurement as a surrogate for intracranial pressure (ICP) by comparing PIN with simultaneously epidural ICP measurement as the standard. Methods Seventeen consecutive patients undergoing neuroendoscopy were studied prospectively. Type and length of procedure and PIN and epidural ICP values during neuroendoscopy were recorded. Lins concordance coefficient and Bland-Altman analysis of agreement were used to assess correspondence between the 2 systems. Results A consistent relation between PIN and epidural ICP waveforms was observed during neuroendoscopic navigation. A strong Pearson correlation between PIN and epidural ICP data were found in 15 patients. Epidural ICP values were systematically higher than PIN values in 15 patients. Lin concordance coefficients showed moderate global agreement between the 2 methods, at 0.58 (95% confidence interval, 0.577-0.592). In 6 cases (35.2%) concordance was good according to this analysis, in 7 cases (41.2%) agreement was moderate/fair, and in 4 cases (23.5%) agreement was poor. The Bland-Altman analysis of patient data showed good agreement between the PIN and epidural ICP measurements for most patients, although discrepancies were greater at higher ICP values for 11 patients. Bland-Altman analysis of the complete dataset, after the normalization of individuals measurements, showed good overall agreement. Conclusions PIN measurement seems useful for evaluating ICP changes related to neuroendoscopic procedures and seems to be more consistent than epidural ICP at high pressures.

Feasibility of microdialysis to determine interstitial rocuronium concentration in the muscle tissue of anesthetized neurosurgical patients.

Background Microdialysis is used to determine the concentrations of substances in the extracellular fluid of tissues. To date, it has not been used to measure rocuronium concentrations in human muscle. We determined the ability of microdialysis to recover rocuronium from muscle interstitial tissue for the purpose of assessing the effect of chronic phenytoin therapy on muscle concentrations of rocuronium. Methods In a first phase, an in vitro study was performed to establish the ability of the assay to recover rocuronium. In a second phase, 17 patients undergoing brain surgery were enrolled. Eight patients were on chronic phenytoin therapy and the remaining 9 patients were not taking any antiepileptic agent (controls). Rocuronium was administered intravenously and muscle tissue samples for microdialysis were collected. Results The recovery rate of the in vitro assay was 36% at a pump rate of 1 μL/min. Rocuronium muscle tissue concentrations could be measured in 25 microdialysate samples. Rocuronium concentrations were similar in patients treated with phenytoin and in controls, although the doses required to obtain a similar effect were significantly higher in patients on chronic phenytoin treatment. Conclusions Quantification of drug concentrations in muscle by means of microdialysis is technically feasible in the clinical setting and it might help in studying pharmacologic mechanisms of drug action. Based on our results the decrease in the degree of effect of rocuronium in the presence of chronic phenytoin therapy might seem to be due mainly to a pharmacokinetic mechanism.

Monitoramento de pacientes neurocirúrgicos no pós‐operatório – utilidade dos escores de avaliação neurológica e do índice bispectral

BACKGROUND AND OBJECTIVES We examined the additive effect of the Ramsay scale, Canadian Neurological Scale (CNS), Nursing Delirium Screening Scale (Nu-DESC), and Bispectral Index (BIS) to see whether along with the assessment of pupils and Glasgow Coma Scale (GCS) it improved early detection of postoperative neurological complications. METHODS We designed a prospective observational study of two elective neurosurgery groups of patients: craniotomies (CG) and non-craniotomies (NCG). We analyze the concordance and the odds ratio (OR) of altered neurological scales and BIS in the Post-Anesthesia Care Unit (PACU) for postoperative neurological complications. We compared the isolated assessment of pupils and GCS (pupils-GCS) with all the neurologic assessment scales and BIS (scales-BIS). RESULTS In the CG (n=70), 16 patients (22.9%) had neurological complications in PACU. The scales-BIS registered more alterations than the pupils-GCS (31.4% vs. 20%; p<0.001), were more sensitive (94% vs. 50%) and allowed a more precise estimate for neurological complications in PACU (p=0.002; OR=7.15, 95% CI=2.1-24.7 vs. p=0.002; OR=9.5, 95% CI=2.3-39.4). In the NCG (n=46), there were no neurological complications in PACU. The scales-BIS showed alterations in 18 cases (39.1%) versus 1 (2.2%) with the pupils-GCS (p<0.001). Altered CNS on PACU admission increased the risk of neurological complications in the ward (p=0.048; OR=7.28, 95% CI=1.021-52.006). CONCLUSIONS Applied together, the assessment of pupils, GCS, Ramsay scale, CNS, Nu-DESC and BIS improved early detection of postoperative neurological complications in PACU after elective craniotomies.

Mechanical thrombectomy in acute basilar artery occlusion: A safety and efficacy single centre study.

Objectives The objective of this study was to add more evidence about the efficacy and safety of mechanical thrombectomy in patients with basilar artery occlusion and secondarily to identify prognostic factors. Methods Twenty-two consecutive patients (mean age 60.5 years, 15 men) with basilar artery occlusion treated with mechanical thrombectomy were included. Clinical, procedure and radiological data were collected. Primary outcomes were the modified Rankin scale score with a good outcome defined by a modified Rankin scale score of 0–2 and mortality rate at three months. Results The median National Institutes of Health stroke scale at admission was 24 (interquartile range 11.5–31.25). Twelve patients (54.5%) required tracheal intubation due to a decreased level of consciousness. Successful recanalisation (modified treatment in cerebral ischaemia scale 2b–3) was achieved in 20 patients (90.9%). A favourable clinical outcome (modified Rankin scale score 0–2) was observed in nine patients (40.9%) and the overall mortality rate was 40.9% (nine patients). Haemorrhagic events were observed in three patients (13.63%). A decreased level of consciousness requiring intubation in the acute setting was more frequent in patients with poor outcomes (84.6%) than in patients with favourable outcomes (11.1%), and in patients who died (100%) compared with those who survived (23.1%), with a statistically significant difference (P = 0.002 and P = 0.001, respectively). Conclusion Mechanical thrombectomy is feasible and effective in patients with acute basilar artery occlusion. A decreased level of consciousness requiring tracheal intubation seems to be a prognostic factor and is associated with a poor clinical outcome and higher mortality rate. These initial results must be confirmed by further prospective studies with a larger number of patients.

Eficacia diagnóstica y manejo posoperatorio de los pacientes sometidos a biopsia cerebral en un hospital universitario

OBJECTIVE To assess the diagnostic yield and the incidence of perioperative complications in patients undergoing an open or closed cerebral biopsy and to determine the length of intensive care monitoring, for early diagnosis and fast management of perioperative complications. MATERIAL AND METHOD This was a retrospective analysis of all the patients that underwent brain biopsy between January 2006 and July 2012. We recorded demographic data, comorbidities, modality of biopsy, intraoperative clinical data, histological results, computed tomography scanning findings and occurrence, and type of perioperative complications and moment of appearance. RESULTS Seventy-six brain biopsies in 75 consecutive patients (51 closed and 25 open) were analysed. Diagnostic yield was 98% for closed biopsies and 96% for open biopsies. Mortality related to the procedures was 3.9 and 4%, respectively. The incidence of major complications was 3.9% for closed biopsies and 8% for open biopsies; half of these appeared within the first 24 postoperative hours, during patient stay in the Intensive Care Unit. Age was the only risk factor for complications (P=.04) in our study. No differences in morbimortality were found between the studied groups. CONCLUSIONS Diagnostic yield was very high in our series. Because the importance of early diagnosis of complications for preventing long-term sequelae, we recommend overnight hospital stay for observation after open or closed brain biopsy.