British journal of neurosurgery
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The objective was to measure metabolic changes monitored by bedside microdialysis during impending and manifest hypoxia in traumatic brain injury. In 41 patients, a PtiO2-catheter (Licox; 1/min) was placed into non-lesioned frontal white matter together with a microdialysis catheter (CMA, hourly). Data were analysed for identification of episodes of impending (PtiO2 < 10 - 15 mmHg > 5 min) and manifest cerebral hypoxia (PtiO2 < 10 mmHg, > 5 min). ⋯ We conclude that hyperventilation had a potential adverse effect on cerebral metabolism and was most frequently associated with cerebral hypoxia. A PtiO2 < 10 mmHg can induce metabolic changes with increase of glutamate and lactate. The presence of anaerobic cerebral metabolism probably depends on duration and severity of the hypoxic episode.
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The results of a recently concluded phase III study have shown that Gliadel therapy (biodegradable polymer impregnated with 3.85% BCNU placed into the surgical cavity) significantly prolongs survival and time to relapse in patients having initial resective surgery for malignant glioma followed by radiotherapy. The indications and exclusion criteria for patients in this study were well defined. To determine the relative frequencies of Gliadel 'eligible' and 'ineligible' patients, and differences in prognostic variables between these two cohorts, we conducted a review of all Edinburgh patients with an initial diagnosis of malignant glioma managed throughout the period of patient accrual into the phase III Gliadel study (Edinburgh was one of 38 contributing centres). ⋯ Only 25% of patients (14/56) with malignant glioma managed over this period were eligible for the Gliadel study and all were recruited. The patients in the study group were younger (median 51 v. 59 years, p = 0.085); in better clinical grade (median Karnofsky score 85 v. 80, p = 0.038); more likely to have resective surgery (86% v. 38%, p = 0.0001); more likely to have postoperative radiotherapy (93% v. 55%, p = 0.0001) and more likely to survive longer, even though one half of the Gliadel cohort received placebo, (66 v. 19 weeks, p = 0.06) than those not eligible. If the future use of Gliadel is limited to the eligibility criteria used in the phase III trial about 20% (95% confidence intervals 13-34%) of patients with newly diagnosed malignant glioma will receive this therapy.
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The objective of the present study was to test the new continuous intracranial compliance (cICC) device in terms of data quality, relationship to intracranial pressure (ICP) and brain tissue oxygenation (PtiO2). A total of 10 adult patients with severe traumatic brain injury underwent computerized monitoring of arterial blood pressure, ICP, cerebral perfusion pressure, end-tidal CO2, cICC and PtiO2 providing a total of 1726 h of data. (1) The data quality assessed by calculating the 'time of good data quality' (TGDQ, %), i.e. the median duration of artefact-free time as a percentage of total monitoring time reached 98 and 99% for ICP and PtiO2, while cICC measurements were free of artefacts in only 81%. (2) Individual regression analysis showed broad scattered correlation between cICC and ICP ranging from low (r = 0.05) to high (r = 0.52) correlation coefficients. (3) From 225 episodes of increased ICP (ICP > 20 mmHg > 10 min), only 37 were correctly predicted by a preceding decline in cICC to pathological values (< 0.5 ml/mmHg). (4) In all episodes of cerebral hypoxia (PtiO2 < 10 mmHg > 10 min), cICC was not pathologically altered. Based on the present results, we conclude that the current hardware and software version of the cICC monitoring system is unsatisfactory concerning data quality, prediction of increased ICP and revelance of cerebral hypoxic episodes.