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Biomedical subjects

R N Wohns

Publications and source records attributed to R N Wohns.

10 recordsLinked to original sources
PubMed1987

Effect of high altitude on the visual evoked responses in humans on Mt. Everest.

Cerebral visual evoked potentials (VEPs) were collected over a 1-year period from the summer of 1983 through the summer of 1984 from 16 members of the American Ultima Thule Everest Expedition at sea level and at altitudes of 7,100 ft, 16,800 ft, and 21,300 ft. VEPs in response to 100 unilateral LED flashes were processed by a modified Nicolet CA-1000 computer of average transients with an analysis time of 250 ms and were recorded by an X-Y plotter. Readings of oxygen saturation, tetrapolar impedance pulmonary plethysmography, and clinical signs and symptoms of acute mountain sickness (AMS) were recorded. The latency of the major waves of the VEPs increased on initial arrival at higher altitude and returned toward base line over time with acclimatization. There were more acute latency changes in individuals who suffered from symptoms of AMS, which reversed with amelioration of symptoms.

Acclimatization↗
PubMed1986

Phenytoin and acute mountain sickness on Mount Everest.

Twenty-one climbers who were members of the American Ultima Thule Everest Expedition participated in a double-blind, randomized clinical trial of phenytoin prophylaxis for acute mountain sickness during the approach to the northeast ridge of Mount Everest. The study was carried out between Beijing and base camp at 16,800 feet. Time spent ascending from Beijing to base camp averaged 13 days. High-altitude symptom questionnaires were filled out beginning in Lhasa at 11,800 feet and in Xigatse at 12,000 feet, in Xegar at 14,000 feet, and at base camp. Computer analysis of the questionnaire answers performed by an impartial analyst revealed that climbers who took phenytoin were less likely to have headaches at base camp. No other statistically significant differences were observed, but the power of the sample size was low.

Acute Disease↗
PubMed1986

Transient ischemic attacks at high altitude.

The precise etiology of transient neurologic deficits at high altitude is unclear, particularly since the subjects are not investigated as they would be had the events occurred in an urban environment. This report describes two subjects who experienced transient ischemic attacks (TIAs) while ascending the northeast ridge route of Mt. Everest during the Ultima Thule Everest Expedition, and a third subject with TIAs during three separate high-altitude climbs. Possible etiologies and treatment for TIAs at high altitude are suggested.

Adult↗
PubMed1985

Cerebral etiology of acute mountain sickness: a case report.

The authors report a case of acute mountain sickness (AMS) experienced by a support member of the Ultima Thule Everest Expedition. The subject arrived at the 17,000-ft base camp by truck and then developed the symptoms of AMS over the following 72 hours. Flash-induced visual evoked responses (VERs), tetrapolar impedance pulmonary plethysmography, and oxygen saturation measurements were performed. These changed from normal before the onset of his symptoms to abnormal during the height of the symptoms and reverted to normal after treatment. This is the first reported case of AMS monitored with VERs. It has been postulated that AMS may be an early form of cerebral edema, and this report corroborates this hypothesis.

Adult↗
PubMed1982

The role of dilantin in the prevention of pulmonary edema associated with cerebral hypoxia.

Twenty-five mongrel dogs were subjected to isolated cerebral hypoxia or noncerebral systemic hypotension to create the congestive pulmonary lesions of the shock lung syndrome (SLS). Eleven of the experimental dogs were pretreated with 5, 5-diphenylhydantoin (DPH). Prophylactic DPH protects the lung from the injury that is a consequence of hypoxic cerebral perfusion in the dog, but does not afford protection from pulmonary damage caused by isolated, noncerebral systemic hypotension. DPH confers this protection on the brain; there is no evidence that DPH exerts this protective effect by an action on the pulmonary parenchyma directly or on other tissue in the body.

Animals↗
PubMed1980

Spinal epidural neoplasia. A 15-year review of the results of surgical therapy.

The outcome following decompressive laminectomy and spinal irradiation has been evaluated in 104 consecutive patients with epidural metastatic neoplasia, using broad criteria for successful outcome. Of patients so treated, 33% were benefited, while 23% became worse. Both tumor histology and the preoperative neurological status were important factors in determining the response to this therapy. The authors review the surgical and radiotherapeutic literature in the treatment of this condition, and conclude that there is no clearly established superiority of laminectomy followed by irradiation over radiotherapy alone. Specific indications for surgery exist if prior histological confirmation of malignancy is lacking, if there is neurological deterioration during radiotherapy, or if there are recurrent symptoms referable to a previously irradiated metastasis. Surgery is also indicated if facilities for prompt administration of radiotherapy are unavailable.

Aged↗
PubMed1979

Prophylactic phenytoin in severe head injuries.

We are reporting a retrospective study of 62 patients whose head injury was sufficiently severe to cause a high probability of posttraumatic epilepsy. Of 50 patients treated with phenytoin, 10% developed epilepsy of late onset. Twelve patients not treated with phenytoin but who had head injuries of equal magnitude had a 50% incidence of epilepsy. These data from a highly selected group of patients with severe head injuries confirm the bias that treatment with phenytoin decreases the incidence of posttraumatic epilepsy.

Adult↗