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PubMed1984

Brain metabolism during increased intracranial pressure as assessed by niroscopy.

Intracranial pressure was increased in cats by infusion of "mock" cerebrospinal fluid into the cisterna magna. This condition was then treated by hyperventilation. In addition to direct measurement of intracranial pressure, cerebral metabolism was assessed by near infrared spectrophotometric (niroscopic) measurement of cytochrome a,a3 redox state and the quantity of reduced and oxygenated hemoglobin in the illuminated brain. Cerebral perfusion was assessed by injection of Cardio-Green. Increased intracranial pressure resulted in the expected reduction in cytochrome a,a3,a decrease in HbO2, an increase in Hb, and a reduction of blood flow. The vasoconstriction produced by hyperventilation, while reducing intracranial pressure, produced a further reduction in cytochrome a,a3 and HbO2, with no improvement in blood flow. The data illustrate the fallacy of governing therapy solely by intracranial pressure and demonstrate the need for a direct assessment of brain metabolism. The data also demonstrate the strengths and weaknesses of niroscopy as a noninvasive monitor of the brain metabolism if applied to patients at risk for increased intracranial pressure.

Animals↗

PubMed1983

An evaluation of perfluorochemical resuscitation after hypoxic hypotension.

The relative performance of whole blood and saline, a balanced salt-albumin solution, and Fluosol-43 were compared in an experimental animal model of combined hypoxia and hypotension. The test fluids were evaluated in terms of their respective ability to restore mean arterial pressure and provide adequate oxygen to restore and maintain a normal brain cytochrome a,a3 redox state, restore and sustain normal cerebral cortical ATP and creatinine phosphate concentrations (CP), and return cerebral cortical lactate concentrations to normal after the hypoxic-hypotensive period. With regard to ATP, CP, lactate, and cytochrome a,a3, all three test fluids performed equally well inasmuch as there were no significant differences between groups. None of the test regimens resulted in normal ATP concentration post-hypoxic hypotension. Although CP concentrations were lower than baseline after resuscitation, the difference was not statistically significant. Fluosol-43 resuscitation resulted in a significantly higher (p less than 0.05) mean arterial pressure by 120 minutes post-resuscitation. It was concluded that Fluosol-43 is an acceptable resuscitative fluid, most beneficial at extremely low hematocrits, but that selection of Fluosol-43 over balanced salt-albumin could not be supported when post-resuscitation hematocrits were in the 20 to 25% range.

Adenosine Triphosphate↗