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. Lin's 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 individual's 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.

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 BIS and other electrophysiologic and clinical variables has enabled construction and cross-validation of a model relating BIS(max) 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 target-controlled infusion to achieve an initial steady state concentration of 1 microg/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 C(50) for Ramsay scores 3, 4, and 5 were 0.1, 1.02, and 2.28 microg/ml, respectively. For airway obstruction scores 2 and 3, the estimates of C(50) were 0.32 and 2.98 microg/ml, respectively. Estimates of k(e0) 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 microg/ml eliciting a sedation score of 3 with only minimal, if any, airway obstruction has been defined as the therapeutic target.

Pronóstico de la hemorragia subaracnoidea espontánea. Relación entre la glucemia al ingreso y el estado clínico al ingreso y al alta hospitalaria / Outcome after spontaneous subarachnoid haemorrhage. Relationship between admission glycemia and clinical status on admission and hospital discharge

Fundamento: Determinar la relación entre la glucemia al ingreso posthemorragia subaracnoidea espontánea y el estado neurológico. Pacientes y método: En 44 pacientes se determinó la glucemia al ingreso y se valoraron las escalas 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 Hunt y Hess IV-V y escala del coma de Glasgow 3 a 8 presentaron glucemias mayores que los pacientes con escala de Hunt y Hess I-III y un valor de escala de coma de Glasglow 9 a 15. Los pacientes con escala de Hunt y Hess IV-V al alta presentaron glucemias mayores que los pacientes con escala de Hunt y Hess I-III. Conclusiones: La glucemia al ingreso se correlacionó con la gravedad de la lesión cerebral aguda y constituyó un factor pronóstico evolutivo de la hemorragia subaracnoidea espontánea. (AU)