Salvador L

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 Methods:Twenty-five critically ill, unconscious brain-injured patients from whom sedative drugs were withdrawn at least 24 h before BIS recording were prospectively studied.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

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.

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.

Consideraciones anestésicas en una paciente con déficit de pantotenato cinasa tipo 2 (enfermedad de Hallervorden-Spatz) para estimulación cerebral profunda

Resumen La neurodegeneracion asociada al deficit de pantotenato cinasa es una entidad autosomica recesiva secundaria a las mutaciones del gen pantotenato cinasa 2 (PANK2). Clinicamente se caracteriza por anormalidades progresivas del movimiento y demencia. El tratamiento medico de la enfermedad es limitado y la distonia suele ser refractaria, por lo cual la cirugia estereotactica con colocacion de electrodos cerebrales profundos es una opcion terapeutica cada vez mas usada en estos pacientes. Describimos una paciente de 32 anos de edad con distonia severa asociada a deficit de PANK2. Fue programada para tomografia computarizada estereotactica y colocacion bilateral de electrodos en nucleo palido medial, bajo anestesia general para tratar la distonia debilitante y la rigidez generalizada asociada a su enfermedad. Durante la intervencion se realizo el mantenimiento anestesico con propofol, rocuronio y remifentanilo en perfusion, sin ninguna incidencia a destacar durante el procedimiento. Tras la intervencion la paciente fue trasladada a la unidad de cuidados intensivos bajo sedacion farmacologica con remifentanilo para proceder a una educcion lentamente progresiva. La paciente pudo ser dada de alta tras la colocacion del generador y en el seguimiento posterior se ha evidenciado mejoria de los movimientos distonicos. Anesthesia considerations for deep-brain stimulation in a patient with type-2 pantothenate kinase deficiency (Hallervorden-Spatz disease)

Pronóstico de la hemorragia subaracnoidea espontánea. Relación entre la glucemia al ingreso y el estado clínico al ingreso y al alta hospitalaria

Fundamento Determinar la relacion entre laglucemia al ingreso posthemorragia subaracnoideaespontanea y el estado neurologico. Pacientes y metodo En 44 pacientes se determinola glucemia al ingreso y se valoraron lasescalas de coma de Glasgow y de Hunt y Hess(HH), al ingreso, al alta y a los 6 meses. Resultados Los pacientes con escala de Hunty Hess IV-V y escala del coma de Glasgow 3 a 8 presentaron glucemias mayores que los pacientescon escala de Hunt y Hess I-III y unvalor de escala de coma de Glasglow 9 a 15. Los pacientes con escala de Hunt y Hess IV-Val alta presentaron glucemias mayores que lospacientes con escala de Hunt y Hess I-III. Conclusiones La glucemia al ingreso se correlacionocon la gravedad de la lesion cerebralaguda y constituyo un factor pronostico evolutivode la hemorragia subaracnoidea espontanea.

Cerebrospinal Fluid Composition Modifications after Neuroendoscopic Procedures

Normal saline solution is currently used as the ventricular irrigation fluid during neuroendoscopic procedures. The aim of this study is to determine the alterations in the cerebrospinal fluid (CSF) composition after neuroendoscopic interventions. Twenty nine patients who underwent a neuroendoscopic procedure under general anaesthesia were studied. Temperature inside the cerebral ventricle was measured and samples of CSF were taken to determinate oxygen and carbon dioxide partial pressures, pH, base excess, ionised calcium, standard bicarbonate, glucose, sodium, potassium, magnesium, total calcium, proteins, chlorine and osmolality before initiating the irrigation and after the neuronavigation. Patient demographics, neuronavigation time, total fluid volume used and temperature of the irrigation solution and complications that appeared in the first 24 hours were collected. Mean age of the patients was 42+/-18 years. The mean neuronavigation time was 21.5+/-15.4 minutes. The mean amount of saline solution used for irrigation was 919.6+/-994.7 mL. All the values studied in the CSF, except osmolality, showed significant variations. There was a significant correlation between the CSF variation of pH, oxygen and carbon dioxide partial pressures, base excess, standard bicarbonate, glucose and total calcium with respect to the total volume of irrigation solution, but not with respect to the neuronavigation time. A cut-off point of 500 mL of irrigation solution (sensitivity 0.7; specificity 0.87) was related with a CSF pH decrease greater than 0.2. The use of saline as irrigation solution during neuroendoscopic procedures produces important changes in CSF.