People exposed to high altitudes often experience somatic symptoms triggered by hypoxia, such as breathlessness, palpitations, dizziness, headache, and insomnia. Most of the symptoms are identical to those reported in panic attacks or severe anxiety. Potential causal links between adaptation to altitude and anxiety are apparent in all three leading models of panic, namely, hyperventilation (hyp...

CO(2) regulation of lung compliance is currently explained by pH- and CO(2)-dependent changes in alveolar surface forces and bronchomotor tone. We hypothesized that in addition to, but independently of, those mechanisms, the parenchyma tissue responds to hypercapnia and hypocapnia by relaxing and contracting, respectively, thereby improving local matching of ventilation (Va) to perfusion (Q). T...

The present study was designed to determine whether hyperoxia would lower the hypocapnic apneic threshold (AT) during non-rapid eye movement (NREM) sleep. Nasal noninvasive mechanical ventilation was used to induce hypocapnia and subsequent central apnea in healthy subjects during stable NREM sleep. Mechanical ventilation trials were conducted under normoxic (room air) and hyperoxic conditions ...

BACKGROUND Pre-hospital endotracheal intubation for the purpose of controlled ventilation may prevent secondary brain injury in patients with severe head injury. In view of the limited monitoring devices utilized in the pre-hospital setting, little is known about the 'quality' of controlled ventilation initiated in the pre-hospital setting. METHODS Included in this prospective study were 122 ...

Characteristics of the subjective symptomatology of asthma were explored within a group of 100 asthma inpatients. Patients rated the relative frequency with which 77 symptom adjectives were associated with asthma attacks. Key cluster analysis of the full set of 77 adjectives identified 5 symptom clusters: Two Mood clusters, Panic-Fear and Irritability, describe affective states concomitant with...

Neurogenic Control of Cerebral Blood Flow in the Baboon. Effects of Alpha Adrenergic Blockade With Phenoxybenzamine on Cerebral Autoregulation and Vasomotor Reactivity to Changes in Paco2 • Cerebral autoregulation was studied in the baboon by increasing and decreasing cerebral perfusion pressure (CPP) before and after intravenous administration (1..5 mg per kilogram) of a long-acting alpha adre...

Caffeine is one of the most widely consumed psycho-stimulants in the world, yet little is known about its effects on brain oxygenation and metabolism. Using a double-blind, placebo-controlled, randomized cross-over study design, we combined transcranial Doppler ultrasound (TCD) and near-infrared spectroscopy (NIRS) to study caffeine's effect on middle cerebral artery peak blood flow velocity (V...

In this editorial, the issues of hypocapnia and its relation to symptomatic vasospasm, prognosis, and outcome among patients with aneurysmal subarachnoid hemorrhage is discussed. Potential directions for future studies are provided.