Expensive cerebral blood flow measurements alone are useless and misinformative in comatose patients: a comprehensive alternative

Since the first report addressing quantification of cerebral blood flow (CBF), concomitant assessment of cerebral oxygen consumption was also carried out. Over the years, however, some investigators have emphatically and mistakenly addressed cerebral ischemia in comatose patients, on the basis of CBF measurements alone. In contrast, we have repeatedly reported that ischemia in these patients must be precisely evaluated based on CBF-metabolism coupling or uncoupling, rather than CBF alone. Based on these previous findings, we therefore propose a comprehensive alternative approach, namely the evaluation of brain ischemia in comatose patients based on cerebral metabolic parameters, such as cerebral extraction of oxygen or cerebral lactate release, without expensive CBF measurements.

Practical and comprehensive guidelines for bedside cerebral hemometabolic multitherapeutic optimization

In recent years, noncomprehensive "guidelines" were proposed for the management of severe acute brain injuries, focusing strictly on two approaches: 1) to maintain cerebral perfusion pressure anywhere above 70 mm Hg; and 2) to maintain arterial carbon dioxide tension levels above 30 torr. Strictly following these propositions, a recently reported prospective controlled study addressed mortality rates of no less than 75-76%, far worse than mortality rates reported before those "guidelines" were published. As a humanitarian alternative, the present comprehensive guidelines are aimed at addressing practical bedside strategies to manage no only intracranial pressure and cerebral perfusion pressure but also cerebral extraction of oxygen, based on solid previously reported papers which revealed the lowest mortality rates (below 15%) in the pertinent literature, in recent years.

Improving Clinical Outcomes from Acute Subdural Hematomas with the Emergency Preoperative Administration of High Doses of Mannitol: A Randomized Trial

OBJECTIVE To evaluate clinical outcomes and postoperative physiological findings for comatose patients with acute subdural hematomas who received preoperative high-dose mannitol (HDM) versus conventional-dose mannitol treatment. METHODS One hundred seventy-eight adult patients with non-missile, traumatic, acute, subdural hematomas were prospectively and randomly assigned to receive emergency, preoperative, intravenous HDM treatment (91 patients), compared with a control group treated with a lower preoperative mannitol dose (87 patients). RESULTS Preoperative improvement of abnormal pupillary widening was significantly more frequent in the study group than in the control group of patients (P < 0.0001). Preoperative HDM treatment was also associated with significantly better clinical outcomes at 6-month follow-up evaluations (P < 0.01). Postoperative physiological findings revealed statistically significant between-group differences, with higher intracranial pressure and lower cerebral extraction of oxygen (relative cerebral hyperperfusion) in the control group, compared with the HDM group. Postoperative global brain ischemia (abnormally low arteriojugular lactate difference values) was rare and was detected in 2.2 and 3.4% of the patients in the study and control groups, respectively. CONCLUSION Emergency preoperative HDM administration was associated with improved clinical outcomes for patients with acute subdural hematomas. Preoperative improvement of abnormal pupillary widening and better postoperative control of intracranial hypertension and associated relative cerebral hyperperfusion seemed to be relevant factors associated with improved outcomes.

An additional therapeutic effect of adequate hyperventilation in severe acute brain trauma: normalization of cerebral glucose uptake

✓ In a total of 309 frequent serial studies, arteriojugular differences in glucose and oxygen levels were concurrently evaluated in 33 adult patients who were experiencing the most acute phase of severe brain trauma. Hyperventilation therapy was optimized to maintain both normalized intracranial pressure and cerebral extraction of oxygen. Under these circumstances, global cerebral glucose extraction was found to be closest to normal during profound optimized hyperventilation, with PaCO2 levels below 25 mm Hg. In contrast, during normocapnia global cerebral glucose extraction dropped below normal range, indicating impairment of cerebral glucose uptake. Findings from this study show that in severe acute brain injury, optimized hyperventilation exerts an additional metabolic effect with respect to cerebral glucose uptake.