We studied the role of prostaglandins and free radicals in the induction of the functional and morphological pial arteriolar abnormalities produced by concussive brain injury. Anesthetized cats equipped with a cranial window for the observation of the pial microcirculation were subjected to concussive brain injury using a fluid-percussion device following administration of cyclooxygenase inhibi...

INTRODUCTION Cerebral autoregulation (CA) is impaired in a multitude of neurological conditions. Increasingly, clinical studies are correlating the nature of this impairment with prognostic markers. In acute intracerebral haemorrhage (ICH), impairment of CA has been associated with worsening clinical outcomes including poorer Glasgow Coma Score and larger haematoma volume. Hypocapnia has been s...

This study examined the dynamics of the middle cerebral artery (MCA) blood flow response to hypocapnia in humans (n = 6) by using transcranial Doppler ultrasound. In a control protocol, end-tidal PCO2 (PETCO2) was held near eucapnia (1.5 Torr above resting) for 40 min. In a hypocapnic protocol, PETCO2 was held near eucapnia for 10 min, then at 15 Torr below eucapnia for 20 min, and then near eu...

Respiration is a complex physiological system affecting a variety of physical processes that can act as a critical link between mind and body. This review discusses the evidence for dysregulated breathing playing a role in three clinical syndromes: panic disorder, functional cardiac disorder, and chronic pain. Recent technological advances allowing the ambulatory assessment of endtidal partial ...

The effects of induced hypocapnia, hypothermia, and hypertension were surveyed in a primate model of acute stroke during and following a 48-hour period of intensive care. The results were compared to a group of nine control animals previously studied. Hypocapnia (PaCO2=25 torr) was examined in five animals and did not appear to alter the expected mortality, degree of neurological deficit, or fr...

We used a wedged bronchoscope technique in conjunction with an in situ isolated perfused left lower lobe preparation in anesthetized dogs to examine cold-associated airway modulation of peripheral lung responses to dry airflow, hypocapnia, and aerosols of histamine and hypertonic NaCl. In this preparation, airway wall temperature was rapidly lowered by decreasing the temperature of blood perfus...

In 10 anaesthetized and ventilated baboons a steady level of raised intracranial pressure was achieved by graduated inflation of an extradural balloon. Measurements were made of the ventricular fluid pressure, and of the change in this pressure after injection of 0·05 ml into the ventricle, the volume-pressure response. This response was studied at normocapnia and at hypocapnia (induced by hype...

To determine whether nonchemical inhibition of respiratory activity occurs during inspiratory pressure support (IPS) ventilation (IPSV), respiratory motor output (in 9 subjects), obtained by calculating transdiaphragmatic pressure-time products, and central respiratory output (in 5 subjects), obtained by integrating the electromyographic activity of the diaphragm (EMGdi) during mechanical inspi...

This investigation tests the hypothesis that the normal cerebral image obtained non-invasively during continuous inhalation of C15O2 is related to cerebral blood flow. Trace amounts of CO2 labeled with the positron-emitting radionuclide 15O were administered to 4 normal subjects at normo- and hypocapnia and to 2 of these subjects at hypercapnia. Hypocapnia typically caused a marked decrease in ...