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Biomedical subjects

A Shupak

Publications and source records attributed to A Shupak.

At least 55 records · Page 3Linked to original sources
PubMed1996

Effects of middle ear oxygen and carbon dioxide tensions on eustachian tube ventilatory function.

The objective of this study was to determine the effect of middle ear (ME) gas composition on eustachian tube ventilatory function (ETVF). ETVF was evaluated by using forced-response and inflation-de-flation tests in four alert cynomolgus monkeys during test sessions with different gas compositions. The ME was flushed with one of the four gas mixtures: 1. air; 2. 12% oxygen, 88% nitrogen; 3. 100% oxygen; and 4. 5% carbon dioxide, 21% oxygen, and 74% nitrogen before and during testing. The results documented lower opening, steady-state, and closing pressures, lower passive and active resistance, and greater dilatory efficiency following ME flushes with the hypercarbic and hypoxic gas mixtures when compared to the others. Also, for applied ME overpressure, the maximum pressure change during a swallow, the average pressure drop for all swallows, and the percentage of the applied pressure equalized were greater under hypoxic and hypercarbic conditions. These results show that ME gas composition affects ETVF and support feedback modulation of ME pressure regulation.

Animals↗
PubMed1996

Oxy-helium treatment for refractory neurological decompression sickness: a case report.

A 49-yr-old male presented with paraparesis and urinary incontinence that appeared 10 min after surfacing from a dive. Treatment was started on an extended USN table 6, but the symptoms persisted. Twenty-four hours later, he was treated with oxy-helium table CX-30, resulting in marked improvement in gait and in sensory and motor function. Urodynamic examination indicated an upper motor neuron lesion; bilateral decreased amplitude of the somatosensory evoked potential was found on stimulation of the tibial nerves; no response below the upper limbs was elicited on central motor conduction time (CMCT) testing; MRI showed lesions in the lower dorsal cord. The patient's condition was further improved by an additional 10 hyperbaric oxygenation sessions, with complete restoration of urinary control and virtually complete sensory and motor recovery. Follow-up urodynamic studies were normal. CMCT recordings showed a bilateral lower limb small-amplitude response. The present case reinforces the limited clinical data regarding the value of oxy-helium in the treatment of neurological decompression sickness, even when primary treatment with oxygen tables is unsuccessful.

Ataxia↗
PubMed1995

[Vestibular function in acoustic trauma].

Histological and functional derangement of the vestibular system has been reported in laboratory animals exposed to high levels of noise. However, reports of clinical series give contradictory results with regard to vestibular disturbances in industrial workers and military personnel suffering from noise-induced hearing loss (NIHL). This study evaluates vestibular function in 22 men with documented NIHL and in 21 matched controls, using electro-nystagmography (ENG) and the smooth harmonic acceleration (SHA) test. There was a significantly lower vestibulo-ocular reflex gain (p = 0.05), and a tendency towards decreased caloric response in the patients. There were no differences between patient and control groups in: incidence of vertigo and of spontaneous, positional and positioning nystagmus; directional preponderance and canal paresis in the ENG; or in phase and asymmetry parameters in the SHA test. These results demonstrated a symmetrical, centrally compensated decrease in vestibular end-organ response associated with symmetrical hearing loss in the patients. Statistically significant correlations were found between average hearing loss, and decrease in average vestibulo-ocular reflex gain (p = 0.01) and ENG caloric lateralization (p = 0.02). These correlations might indicate a single mechanism for both cochlear and vestibular NIHL. The results imply subclinical, well compensated malfunction of the vestibular system associated with NIHL.

Hearing Loss, Noise-Induced↗
PubMed1995

Left ventriculography complicated by cerebral air embolism.

Cerebral air embolism is a severe complication of various invasive medical procedures. Hyperbaric oxygen is the sole definitive therapy. We describe a 68-year-old patient who presented with upper left limb motor and sensory deficits following the injection of a contrast medium for left ventriculography. Numerous air bubbles were seen on cineangiography concomitantly with injection of the contrast medium. Immediate compression with hyperbaric oxygen resulted in complete resolution of all neurological symptoms. Iatrogenic cerebral air embolism is an underdiagnosed condition that may result from cardiac catheterization. Physician awareness will improve prevention, and prompt diagnosis and the use of hyperbaric oxygen will result in an optimal outcome if it does occur.

Aged↗
PubMed1995

Necrotizing fasciitis: an indication for hyperbaric oxygenation therapy?

BACKGROUND: The accepted treatment protocol for necrotizing fasciitis (NF) consists of extensive surgery and wide spectrum antibiotics. Hyperbaric oxygenation (HBO) has been recommended as adjuvant therapy for NF, improving patient mortality and outcome. However, the beneficial effect of HBO for NF remains controversial. METHODS: A retrospective evaluation of treatment outcome in 37 patients treated for NF between 1984 and 1993 was carried out. The mortality rate, morbidity criteria, and risk factors for grave prognosis were compared between a group of 25 patients who received HBO as part of their treatment protocol and a group of the remaining 12 patients treated by surgical excision and antibiotics alone. RESULTS: The two groups were found to be similar with regard to age, gender, the incidence of individual risk factors for ominous prognosis, and the Acute Physiology and Chronic Health Evaluation (APACHE) II score for disease's severity on presentation. The mortality rate among the HBO-treated patients was 36%, as opposed to 25% in the non-HBO group. The mean number of surgical débridements required per patient was significantly higher in the HBO group: 3.3 compared with 1.5 in the non-HBO-treated patients. Although the average length of hospitalization for survivors was shorter for the HBO group, the difference between the groups did not reach statistical significance. CONCLUSIONS: The results of this study cast doubt on the suggested advantage of HBO in reducing patient mortality and morbidity when used as adjuvant therapy for NF.

Adolescent↗
PubMed1995

Oxygen diving-induced middle ear under-aeration.

Middle ear negative pressure and effusions have been described after oxygen diving. The prevalence, dynamics and pathophysiology of this phenomenon are not clear, and were hence investigated in the present study. Thirty-four oxygen divers with normal otoscopic and tympanometric evaluation participated in the study. The subjects' symptoms were documented, and pneumatic otoscopy and tympanometry were repeated immediately after the completion of a 3 h, 15 feet oxygen dive, and 7 h later on awakening from the night's sleep. Most divers had positive otoscopic findings the morning after the dive, all of which cleared within 4 h of rising. A significant decrease was observed in average middle ear compliance (p = 0.0463, one way ANOVA), and an increase was found in the number of ears with tympanic compliance less than 0.3 ml (p = 0.0001, Kruskal-Wallis non-parametric ANOVA). In addition, 14.7% of the ears had type C, and 27.9% type B tympanograms the morning after the dive (p = 0.0001 chi2). The generalized nature of oxygen-induced middle ear under-aeration, combined with the dynamics of the symptoms and signs observed, make middle ear barotrauma, tympanic cavity oxygen absorption, and middle ear epithelial oxygen toxicity all unlikely explanations. The observed phenomenon and its dynamics might stem from a reversible derangement in a middle ear chemoreceptor reflex arch, which has recently been suggested as regulating middle ear aeration.

Acoustic Impedance Tests↗
PubMed1995

Motion sickness.

Explore the source record for details and available documents.

Aerospace Medicine↗
PubMed1995

CO2 retention during hyperbaric exercise while breathing 40/60 nitrox.

We evaluated CO2 retention in 24 Navy construction divers breathing air at 1 atm abs (101.3 kPa) and 40% O2 (40/60) nitrox at 4 atm abs (Po2 of 162.1 kPa) inside a pressure chamber. The divers sat immersed to the sternal notch and exercised against pneumatically loaded pedals at a Vo2 of approximately 1.3 liter/min. The mean end-tidal CO2 tension (PET(CO2)2) at 1 atm abs (45.7 +/- 5.0 SD torr) was significantly higher than that of non-divers and diving trainees (40 +/- 5.0) but did not increase significantly at depth (47.1 +/- 6.3). The ranking of CO2 retention was not maintained at depth. Unpredictable upward and downward shifts of up to 10 torr occurred in some divers. The PET(CO2) of six of the divers at pressure was greater than 50 torr, which based on animal studies markedly increases the risk of central nervous system oxygen toxicity. We translated their values into individual depth limits with 40/60 nitrox: three with 50 < PET(CO2) < 55 torr were forbidden to dive beyond 25 m and three with values > 55 torr were restricted to 20 m. We propose that whenever possible, PET(CO2) during exercise at pressure be measured in potential nitrox users and that the above PO2 limits be enforced on moderate and extreme CO2 retainers, respectively.

Adult↗
PubMed1994

[Hyperbaric oxygen for hydrogen sulfide poisoning].

Hydrogen sulfide (H2S) is a toxic gas produced in decaying substances containing organic sulfur. Exposure to the gas causes severe disturbances in the central nervous and respiratory systems. The mechanism of toxicity is disruption of the electron transport chain in mitochondria, resulting in intracellular hypoxia. Treatment of H2S poisoning includes mechanical ventilation with 100% oxygen and immediate administration of sodium nitrate. Treatment with hyperbaric oxygen (HBO) has been studied in animal models, and has also been used in a number of patients. However, the clinical effectiveness of this mode of therapy has not been clearly proven. Having recently treated a case of H2S poisoning, we suggest HBO to reduce mortality.

Humans↗
PubMed1994

Cinnarizine in the prophylaxis of seasickness: laboratory vestibular evaluation and sea study.

Cinnarizine was evaluated for the prevention of seasickness in a laboratory and sea study. The effects of 25 mg cinnarizine on the vestibulo-ocular reflex were investigated in 13 subjects. Significant reduction of the gain in response to sinusoidal oscillations at 0.02, 0.08, and 0.16 Hz (p < 0.05) and increased phase lead at 0.16 Hz (p < 0.01) were observed. The effect of 25 and 50 mg cinnarizine on seasickness severity was examined in 95 subjects during a voyage in rough seas. Seasickness symptoms were improved in 69% of the subjects by 50 mg cinnarizine versus 35% and 31% in the groups receiving 25 mg cinnarizine and placebo (p < 0.05 and p < 0.01, respectively). The percentage of vomiting protection provided by 50 mg cinnarizine was 63% (p < 0.05). We conclude that 50 mg cinnarizine is an effective drug for the prevention of seasickness. The reduction in vestibular sensitivity observed even after administration of 25 mg cinnarizine may explain the potency of cinnarizine in the prevention of seasickness.

Adolescent↗
PubMed1994

Vestibular findings associated with chronic noise induced hearing impairment.

Histological and functional derangements of the vestibular system have been reported in laboratory animals exposed to high levels of noise. However, clinical series describe contradictory results with regard to vestibular disturbances in industrial workers and military personnel suffering from noise induced hearing loss (NIHL). The purpose of the present study was to evaluate vestibular function in a group of subjects with documented NIHL, employing electronystagmography (ENG) and the smooth harmonic acceleration (SHA) test. Subjects were 22 men suffering from NIHL and 21 matched controls. Significantly lower vestibulo-ocular reflex gain (p = 0.05), and a tendency towards decreased caloric responses were found in the study group. No differences in the incidence of vertigo symptoms, spontaneous, positional and positioning nystagmus, directional preponderance and canal paresis in the ENG, or the SHA test phase and asymmetry parameters were observed between the groups. These results demonstrated a symmetrical centrally compensated decrease in the vestibular end organ response which is associated with the symmetrical hearing loss measured in the study group. Statistically significant correlations were found between the average hearing loss, the decrement in the average vestibulo-ocular reflex gain (p = 0.01), and ENG caloric lateralization (p = 0.02). These correlations might indicate a single mechanism for both cochlear and vestibular noise-induced injury. The results imply subclinical, well compensated malfunction of the vestibular system associated with NIHL.

Adolescent↗
PubMed1994

Effect of cinnarizine in the prevention of seasickness.

In a double-blind, placebo-controlled study, we evaluated the effect of two different doses of cinnarizine in the prevention of seasickness in very rough seas. We divided 95 healthy male subjects into 3 groups which received: cinnarizine 50 mg, cinnarizine 25 mg, and placebo. Seasickness susceptibility and severity were evaluated by a standard questionnaire concerning the subject's condition on previous voyages (seasickness susceptibility), and the subject's condition immediately after a 4-6-h voyage in very rough seas with 3.5 m waves (seasickness severity). Possible side effects of the drug were also evaluated by filling in a further questionnaire. Of the 31 subjects who received cinnarizine 50 mg, 65% felt better during the present voyage than on previous voyages, compared to 41% of the 32 subjects who received cinnarizine 25 mg and 31% of the 32 who received placebo. A significant difference (p < 0.05) was found between the cinnarizine 50 mg and placebo groups, while cinnarizine 25 mg was no more effective than placebo. No notable side effects were found for any drug group. In conclusion, cinnarizine 50 mg was found to be effective in the prevention of seasickness in rough seas.

Adolescent↗
PubMed1994

Seasickness susceptibility, personality factors, and salivation.

The present study investigates the possible relationship between motion sickness susceptibility, personality factors and salivation. Personality factors, as evaluated by the Eysenck Personality Questionnaire, and salivary composition and flow were measured in a group of 29 subjects highly susceptible to seasickness and in a group of 25 non-susceptible subjects. The non-susceptible group had significantly higher psychoticism scores and significantly lower salivary amylase levels compared to the highly susceptible group. A significant positive correlation was found between psychoticism scores and the amount of the increase in salivary flow in response to gustatory stimulation. These results provide more data in support of a connection between motion sickness susceptibility, personality, and the autonomic nervous system.

Adolescent↗
PubMed1993

Vestibulo-ocular reflex in migraine patients: the effect of sodium valproate.

We studied vestibulo-ocular reflex measurements in a group of 12 patients suffering from migraine without aura and evaluated the effect of sodium valproate given as prophylactic migraine therapy. The study was randomized, double blind and placebo controlled, with a crossover design. The horizontal vestibulo-ocular reflex was evaluated by the Sinusoidal Harmonic Acceleration test at 0.01, 0.02, 0.04, 0.08 and 0.16 Hz using a computerized rotatory chair system. No abnormalities were found for the vestibulo-ocular reflex gain, phase and asymmetry at each of the frequencies examined during the placebo treatment. These normal vestibulo-ocular reflex measurements contrasted with the repeated complaints of dizziness, vertigo and unsteadiness reported by 7 patients (58%). Sodium valproate affected neither vestibulo-ocular responses nor vestibular complaints but was effective in reducing migraine attacks in 8 of the 12 patients. These results demonstrate that the low frequency vestibulo-ocular reflex measurements are normal in patients suffering from migraine without aura.

Adult↗
PubMed1992

Salivary secretion and seasickness susceptibility.

The salivary flow rate and composition of 2 groups of 31 subjects, one group at each extreme of the seasickness susceptibility scale, were compared. No significant differences were found between the two groups in flow rates and electrolyte concentrations of whole resting and stimulated saliva. Amylase activity and rate of secretion in resting saliva were significantly higher in subjects susceptible to seasickness as compared with nonsusceptible subjects. Also, the total protein rate of secretion in resting saliva was significantly higher in the susceptible group. The present findings could be explained in terms of higher sympathetic tone in subjects susceptible to seasickness, and salivary amylase levels might be recommended as an additional parameter in the evaluation of seasickness susceptibility.

Adult↗