Effects of hyperbaric oxygenation.

OBJECT: Hyperbaric oxygenation (HBO) therapy has been shown to reduce mortality by 50% in a prospective randomized trial of severely brain injured patients conducted at the authors' institution. The purpose of the present study was to determine the effects of HBO on cerebral blood flow (CBF), cerebral metabolism, and intracranial pressure (ICP), and to determine the optimal HBO treatment paradigm. METHODS: Oxygen (100% O2, 1.5 atm absolute) was delivered to 37 patients in a hyperbaric chamber for 60 minutes every 24 hours (maximum of seven treatments/patient). Cerebral blood flow, arteriovenous oxygen difference (AVDO2), cerebral metabolic rate of oxygen (CMRO2), ventricular cerebrospinal fluid (CSF) lactate, and ICP values were obtained 1 hour before and 1 hour and 6 hours after a session in an HBO chamber. Patients were assigned to one of three categories according to whether they had reduced, normal, or raised CBF before HBO. In patients in whom CBF levels were reduced before HBO sessions, both CBF and CMRO2 levels were raised 1 hour and 6 hours after HBO (p < 0.05). In patients in whom CBF levels were normal before HBO sessions, both CBF and CMRO2 levels were increased at 1 hour (p < 0.05), but were decreased by 6 hours after HBO. Cerebral blood flow was reduced 1 hour and 6 hours after HBO (p < 0.05), but CMRO2 was unchanged in patients who had exhibited a raised CBF before an HBO session. In all patients AVDO2 remained constant both before and after HBO. Levels of CSF lactate were consistently decreased 1 hour and 6 hours after HBO, regardless of the patient's CBF category before undergoing HBO (p < 0.05). Intracranial pressure values higher than 15 mm Hg before HBO were decreased 1 hour and 6 hours after HBO (p < 0.05). The effects of each HBO treatment did not last until the next session in the hyperbaric chamber. CONCLUSIONS: The increased CMRO2 and decreased CSF lactate levels after treatment indicate that HBO may improve aerobic metabolism in severely brain injured patients. This is the first study to demonstrate a prolonged effect of HBO treatment on CBF and cerebral metabolism. On the basis of their data the authors assert that shorter, more frequent exposure to HBO may optimize treatment.

A portable microvascular laboratory for the office.

Regular exercises in microsurgery are mandatory for the microsurgeon to develop and maintain skill. Not all microsurgeons have access to a hospital or university laboratory in which to perform such microsurgical procedures. The authors describe a simple model for a portable microvascular laboratory that can be set up in an office.

Hyperbaric oxygenation for the treatment of acute cerebral edema.

A multifaceted therapeutic approach to the treatment of traumatic cerebral edema includes methods to reduce intracranial pressure and combat both ischemia and hypoxia. Hyperbaric oxygenation can be effective in reducing intracranial pressure by decreasing cerebral blood flow. Its ability to concomitantly increase cerebral oxygenation suggests its applicability for the treatment of traumatic cerebral edema. Our findings in 50 patients treated at 2 atm absolute support these contentions.

Cerebellar stimulation for chronic extensor-flexor rigidity and opisthotonus secondary to hypoxia. Report of two cases.

Two patients with chronic hypertonus (in a decerebrate state) as a result of hypoxia are described. Long-term cerebellar stimulation markedly modified their extraordinarily severe extensor-flexor rigidity phenomena that had resulted in chronic opisthotonus.