1036 Such anxiety is known to be associated with enhanced activity of ascending brainstem noradrenergic pathways. 37 In the only very limited study so far published, Raichle and his co-workers38 suggested that this system may increase vascular permeability within the brain as well as possibly affecting vascular calibre. This finding is analogous to the findings in adipose and other tissues.3y Perhaps anxiety-among many other actions (including enhanced adrenal medullary secretion) may increase brain-vascular permeability sufficiently in some individuals for these circulating agents to have a central effect.

migraine attacks.

Methods and Devices POSITIVE EXPIRATORY PRESSURE FOR THE TREATMENT OF HIGH-ALTITUDE

PULMONARY ŒDEMA KENNETH W. FELDMAN

S. PAUL HERNDON

Odessa Brown Children’s Clinic and Cardiology Division, Children’s Orthopedic Hospital and Medical Center, Seattle, Washington, U.S.A.

POSSIBLE METHODS FOR EXAMINING THE HYPOTHESIS

The responses of the cerebral circulation of normal individuals to vasoactive agents has been examined and little change noted.19 Is the reactivity of the cerebral vasculature of migraine patients to amines and prostaglandins any different, either between or during attacks? Is the permeability of the blood-brain barrier towards The agents in man any different in migraine patients? 4U Pertwo to these answer exists questions.6 technology haps advantage might be taken of the fact that agents such as tyramine and phenylethylamine can precipitate migraine in sensitive individuals in order to study the c.B.F. and barrier changes, but we are fully appreciative of the ethical considerations which might inhibit such

investigations. suggest that the evidence from laboratory investigations and clinical studies provides support In summary,

we

hypothesis that the blood-brain barrier in migraine patients may be defective, perhaps only transiently or focally, either in the structural or the enzymafor the

DEATHS from high-altitude pulmonary oedema (H.A.P.O.), which is a severe complication of acute mountain sickness

(A.M.S.), are increasing as mountaineering becomes a more popular recreation. Of 310 persons attempting to climb Mount McKinley (Alaska) in 1976 by the West Buttress or Muldrow Glacier routes, 1 died and 6 required evacuation because of

Additionally, in an evacuation attempt of another victim on another route, two rescuers were killed and two injured. The overall incidence of A.M.s. was 53% in unacclimatised hikers at 4243 m in the Himalayas of Nepal and was as high as 85% of a group of subjects who had flown to 2800 m, made a rapid rate of ascent from that point, and spent a limited time becoming acclimatised.1 The aetiology of H.A.P.O. is unknown but raised pulmonaryartery pressure has been demonstrated in the presence of normal left atrial and pulmonary artery wedge pressures.3-J Arterial leakage is present" and interstitial oedema may precede frank pulmonary

Positive expiratory pressure for the treatment of high-altitude pulmonary oedema.

1036 Such anxiety is known to be associated with enhanced activity of ascending brainstem noradrenergic pathways. 37 In the only very limited study so...
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