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Biomedical subjects

F K Butler

Publications and source records attributed to F K Butler.

9 recordsLinked to original sources
PubMed1992

Altitude retinopathy on Mount Everest, 1989.

The authors studied prospectively the incidence of and risk factors for high altitude retinal hemorrhages among 14 members of the 1989 American Everest Expedition. All subjects had comprehensive eye examinations and fundus photography performed at sea level before the expedition and again at the Mt. Everest Base Camp after 6 weeks of exposure to altitudes between 5300 and 8200 meters. Asymptomatic intraretinal hemorrhages were found in five eyes of four climbers. An additional eye of one of these climbers had a central retinal vein occlusion with vitreous hemorrhage, which reduced visual acuity to counting fingers. Higher baseline intraocular pressure and use of nonsteroidal anti-inflammatory drugs were found to be significant risk factors for development of altitude retinopathy.

Acclimatization↗
PubMed1991

Decompression sickness presenting as optic neuropathy.

Decompression sickness (DCS) is a systemic disorder caused by an abrupt decrease in the ambient atmospheric pressure to which an individual is exposed. A previously healthy 23-year-old male parachutist developed optic neuropathy after a series of multiple repeated hypobaric exposures; his symptoms improved promptly with recompression and hyperbaric oxygen therapy. We believe this to be the first reported case of DCS presenting as optic neuropathy.

Adult↗
PubMed1987

Visual reaction time performance preceding CNS oxygen toxicity.

The visual reaction time performance of divers experiencing CNS oxygen toxicity was assessed during the development of closed-circuit 100% oxygen breathing diving schedules at the U.S. Navy Experimental Diving Unit. Divers repeatedly performed the visual reaction time test of the Performance Measurement System (PMS) during multiple excursion dives. Each diver wore a Draeger LAR V UBA and performed moderate work on an underwater bicycle ergometer while engaged in the reaction time test. A single subject, repeated measures design was used. Six divers experienced 7 episodes of CNS oxygen toxicity while engaged in the visual reaction time test. Two episodes were preceded by a slowing and increase in variability of reaction time. Five episodes were not preceded by changes in reaction time performance. Other objective and subjective symptoms of toxicity experienced by the divers did not appear to be correlated with reaction time performance. Thus, the PMS visual reaction time test was not reliable method of detecting CNS oxygen toxicity in this study.

Adult↗
PubMed1986

Progressive ulnar palsy as a late complication of decompression sickness.

We report an unusual case of decompression sickness in which a progressive ulnar palsy developed 22 days after the onset of neurological decompression sickness. The initial symptoms of numbness and paresthesias of the hand were treated with recompression therapy, resulting in only partial relief. The patient subsequently developed weakness of the left hand, which increased in severity until the institution of repeated daily hyperbaric oxygen treatments. A total of seven treatments resulted in partial resolution of the patient's signs and symptoms. Recovery was complete within four months.

Adult↗
PubMed1986

The application of positron emission tomography to the study of panic disorder.

Positron emission tomography was used to study eight patients with panic disorder who were vulnerable to lactate-induced panic, eight patients with panic disorder who were not vulnerable to lactate-induced panic, and 25 normal control subjects. Patients who were vulnerable to lactate-induced panic had several abnormalities in the resting, nonpanic state: an abnormal hemispheric asymmetry of parahippocampal blood flow, blood volume, and oxygen metabolism; abnormally high whole brain metabolism; and abnormal susceptibility to episodic hyperventilation. A hypothetical model for the neurobiology of panic disorder, involving the abnormal parahippocampal region and its afferent and efferent connections, is proposed.

Adult↗
PubMed1986

Screening for oxygen intolerance in U.S. Navy divers.

All U.S. Navy diving candidates are screened for their tolerance to hyperbaric oxygen by taking an oxygen tolerance test (OTT). During a recent experimental oxygen dive series at the U.S. Navy Experimental Diving Unit, three divers were noted to be reproducibly oxygen sensitive. These three divers were then given additional OTTs to see if any evidence of central nervous system oxygen toxicity would be detected by these multiple tests. The additional OTTs did not produce any signs or symptoms of oxygen toxicity in these already proven susceptible divers. A subsequent review of the records of the Naval Safety Center yielded a total of 1347 OTTs from 1 January 1972 to 31 December 1981. A review of diving accidents reported during this period revealed that 26 episodes of oxygen toxicity were noted during OTTs for a derived failure rate of 1.9%. Analysis of oxygen toxicity episodes encountered during operational Navy diving for this period found that 9 episodes of nonconvulsive oxygen toxicity were seen in mixed gas diving and 3 episodes of nonconvulsive oxygen toxicity were noted in closed circuit oxygen diving. Conclusions from this paper are: Screening for oxygen intolerance is complicated by intraindividual variation in oxygen tolerance; U.S. Navy diving using 100% oxygen during the period studied has had an acceptable safety record according to the data on record at the Naval Safety Center; the OTT as currently administered by the U.S. Navy does not identify all individuals who are relatively susceptible to oxygen toxicity; those individuals who do fail the OTT are unusually susceptible to oxygen toxicity; and because of the need to continue to identify these unusually susceptible individuals, the OTT should continue to be administered to U.S. Navy diver candidates.

Adult↗
PubMed1986

A blitz of bends: decompression sickness in four students after hypobaric chamber training.

This paper reports three cases of type II and one case of type I decompression sickness occurring in a group of nine vigorously active US Army parachutists who took a hypobaric chamber HALO (high altitude-low opening) training flight to a maximum altitude of 9,908.5 m (32,500 ft). After the cases of decompression sickness were diagnosed and treated, the aviator mask regulators were checked and found to be functioning properly; the oxygen supply was analyzed and found to be pure. All cases fully recovered after treatment on US Navy Diving Table 6 and have returned to full military duty. This HALO training profile is not in use with either the US Navy or the US Air Force and should probably be considered unsafe for future use in training.

Adult↗
PubMed1986

Central nervous system oxygen toxicity in closed circuit scuba divers II.

Central nervous system oxygen toxicity is currently the limiting factor in underwater swimming/diving operations using closed-circuit oxygen equipment. A dive series was conducted at the Navy Experimental Diving Unit in Panama City, FL, to determine whether these limits can be safely extended and also to evaluate the feasibility of making excursions to increased depth after a previous transit at a shallower depth for various lengths of time. A total of 465 man-dives were conducted on 14 different experimental profiles. In all, 33 episodes of oxygen toxicity were encountered, including 2 convulsions. Symptoms were classified as probable, definite, or convulsion. Findings were as follows: symptom classification is a useful tool in evaluating symptoms of oxygen toxicity; safe exposure limits should generally be adjusted only as a result of definite symptoms or convulsions; the following single-depth dive limits are proposed: 20 fsw (6.1 msw)--240 min, 25 fsw (7.6 msw)--240 min, 30 fsw (9.1 msw)--80 min, 35 fsw (10.7 msw)--25 min, 40 fsw (12.2 msw)--15 min, 50 fsw (15.2 msw)--10 min; a pre-exposure of up to 4 h at 20 fsw causes only a slight increase in the probability of an oxygen toxicity symptom on subsequent downward excursions; a pre-exposure depth of 25 fsw will have a more adverse effect on subsequent excursions than will 20 fsw; a return to 20 fsw for periods of 95-110 min seems to provide an adequate recovery period from an earlier excursion and enables a second excursion to be taken without additional hazard; nausea was the most commonly noted symptom of oxygen toxicity, followed by muscle twitching and dizziness; dives on which oxygen toxicity episodes were noted had a more rapid rate of core temperature cooling than dives without toxicity episodes; several divers who had passed the U.S. Navy Oxygen Tolerance Test were observed to be reproducibly more susceptible to oxygen toxicity than the other experimental divers.

Adult↗