Telephone diagnosis of a strange voice.
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Adult↗
Biomedical subjects
Avi Shupak
Publications and source records attributed to Avi Shupak.
Long-term hematological effects in Special Forces trainees.
The present study assesses the impact of "sports anemia" on screening tests performed on participants in an endurance-training program. Medical charts of 48 naval Special Forces trainees and 48 submarine trainees were reviewed. We compared the results of red blood cell count, hemoglobin concentration, hematocrit (Hct), and mean corpuscular volume performed at recruitment and after 2 years. No differences were noted between baseline values. The Hct and red blood cell count decreased significantly in the Special Forces trainees after 2 years of training (p = 0.002 and p = 0.05, respectively), remaining unchanged in the submariners. Hct decreased by 2 +/- 4.14%, whereas red blood cell count decreased by 0.13 +/- 0.44 M/microL. A reduction in Hct may be expected in Special Forces trainees engaged in long-term endurance training. Because these lower values were not seen in an otherwise identical group of submarine trainees, they could be attributed to the endurance training.
Adolescent↗
Training improves divers' ability to detect increased CO2.
BACKGROUND: Elevated arterial PCO2 (hypercapnia) is a known risk in diving with closed circuit breathing apparatus. In a retrospective study, we determined CO2 retention and the ability to detect CO2 in novice divers who were either CO2-recognition-trained subjects (TS) or untrained subjects (UTS). METHODS: Ventilatory and perceptual responses to variations in inspired CO2 (range 0-5.6 kPa, 0-42 mm Hg) during moderate exercise were assessed in novice Israeli Navy divers on active duty. Tests were carried out on 231 TS and 213 UTS. RESULTS: The minimal mean inspired PCO2 that could be detected was 4.8 +/- 1.6 kPa (36 +/- 12 mm Hg) in UTS and 2.9 +/- 0.7 kPa (22 +/- 5 mm Hg) in TS (p < 0.0001). No significant changes were found in PETCO2 between the two groups during exposure to a PICO2 of 5.6 kPa (42 mm Hg). There were 46 TS who were found to be CO2 retainers (more than +1 SD above the mean) and 19 were classified as poor detectors (more than +1 SD above the mean). Seven subjects exhibited both traits. During actual oxygen diving performed later by this group, the only four cases of CNS-oxygen toxicity were among those seven subjects (p < 0.01). CONCLUSIONS: We conclude that CO2 recognition training improves the diver's capability to detect CO2. We suggest that a diver who is both a poor CO2 detector and a CO2 retainer will be prone to CNS-oxygen toxicity.
Adult↗
Pulmonary edema following closed-circuit oxygen diving and strenuous swimming.
Acute pulmonary edema may be induced by diving and strenuous swimming. We report the case of a diver using closed-circuit, scuba equipment who developed acute dyspnea, hemoptysis, and hypoxemia following a dive in 18 degreesC (64.4 degrees F) water and physical exertion during the swim back to shore. With the growing popularity of recreational scuba diving, emergency physicians are liable to be faced with increasing numbers of diving-related medical problems. Diving-induced pulmonary edema should be included in the differential diagnosis of acute hypoxemia, sometimes accompanied by acid-base abnormalities, when this is seen in a diver.
Adult↗
Evaluation of betahistine for the prevention of seasickness: effect on vestibular function, psychomotor performance and efficacy at sea.
Betahistine was evaluated for the prevention of seasickness in a laboratory and sea study. The effect of 48 mg betahistine on the vestibulo-ocular reflex (VOR) and on psychomotor performance was evaluated in twelve young healthy subjects in a double-blind, placebo controlled, randomized, crossover design. The vestibulo-ocular reflex was evaluated by the Sinusoidal Harmonic Acceleration (SHA) test at frequencies of 0.01, 0.02, 0.04, 0.08 and 0.16 Hz. Psychomotor performance was assessed by both computerized and paper and pencil test batteries. No significant differences in VOR gain or phase were found between betahistine and placebo treatment for any of the frequencies tested. No significant differences were found between treatments for any of the psychomotor performance tests or other possible side effects. The effect of 48 mg betahistine on seasickness severity was evaluated in 83 subjects during a voyage in rough seas. Betahistine had a borderline non-statistically significant effect on the prevention of seasickness in comparison with placebo (p = 0.053), with no notable side effects. Although our results are insufficient to recommend betahistine as an anti-seasickness drug, further studies are required to determine its possible effectiveness in less provocative motion sickness situations.
Adult↗
High-frequency sound field and bubble formation in a rat decompression model.
High-frequency sound might cause bubble enlargement by rectified diffusion. The purpose of the present study was to investigate gas bubble formation in the immersed diving animal during exposure to high-frequency sound. Anaesthetised rats were subjected to a simulated diving profile while immersed inside a hyperbaric chamber. An acoustic beacon (pinger) was placed ventral to the animal's abdomen, transmitting at an intensity of 208.9 dB re 1 micro Pa and a frequency of 37 kHz. Six groups of eight animals were included in the study as in Table 1, breathing air (n = 4) or Nitrox 72/28 (n = 2), at a depth of 0 m, 30 m or 40 m. Immediately after decompression, the intestinal mesenterium was imaged, and frames were acquired digitally. The number of bubbles and their radii were analysed and compared among the groups. The mean bubble density for group 1 was 1.35 +/- 0.18 bubbles/mm(2), significantly higher when compared with the other groups (p < 0.0001). The average bubble radius for groups 1 and 2 was similar (12.57 +/- 4.1 and 10.63 +/- 1.8 microm, respectively), but significantly larger than in the other groups (p < 0.0002). The percentage of bubbles with a radius greater than 50 microm was significantly higher in group 1 (p < 0.0001). The results suggest that commercially available underwater pingers might enhance bubble growth during deep air diving.
Acoustics↗
Cardiogenic shock complicating acute carbon monoxide poisoning despite neurologic and metabolic recovery.
We report the cases of 2 previously healthy young patients with acute carbon monoxide intoxication who deteriorated to cardiogenic shock in the face of apparent metabolic and neurologic recovery. Prolonged exposure to sublethal levels of carbon monoxide (>24 hours, carboxyhemoglobin level of 20.4% and 22.6%) and massive binding of the toxin to myocardial myoglobin and mitochondrial cytochrome chain enzymes might explain their protracted cardiac failure. The good response to inotropic agents and the findings of repeated echocardiographic studies support the probable diagnosis of myocardial stunning. Complete cardiac recovery was observed in both patients.
Adult↗
Performance of infusion pumps during hyperbaric conditions.
BACKGROUND: Many hyperbaric facilities use infusion pumps inside the chamber. It is therefore important to ensure that this equipment will perform accurately during hyperbaric conditions. The authors tested the function and accuracy of the Imed 965 and Infutec 520 volumetric infusion pumps, the Easy-pump MZ-257 peristaltic infusion pump, and the Graseby 3100 syringe pump. METHODS: The authors calculated the deviations of infused volumes at low and high rates (12-18 and 60-100 ml/h) on three different hyperbaric protocols (up to 2.5, 2.8, and 6 atmospheres absolute [ATA]), resembling a standard hyperbaric oxygen treatment and US Navy treatment tables used for decompression illness and for arterial gas embolism. Two examples of each pump model were examined in every experiment. RESULTS: The Easy-pump MZ-257 failed to function completely beyond a chamber pressure of 1.4 ATA, making it unsuitable for use inside the hyperbaric chamber. The Graseby 3100 failed to respond to all keyboard functions at 2.5-2.8 ATA, making it unsuitable for use in most hyperbaric treatments. The Imed 965 performed within an acceptable volume deviation (< or =10%) during most hyperbaric conditions. During the compression phase of the profiles used, and for the low infusion rates only, exceptional volume deviations of 20-40% were monitored. The Infutec 520 demonstrated an acceptable deviation (within 10%) throughout all the hyperbaric profiles used, unaffected by changes in ambient pressure or infusion rate. CONCLUSIONS: Commercially available infusion pumps operating during hyperbaric conditions demonstrate substantial variations in performance and accuracy. It is therefore important that the hyperbaric facility staff make a careful examination of such instruments to anticipate possible deviations in the accuracy of the equipment during use.
Humans↗
Active high-frequency vestibulo-ocular reflex and seasickness susceptibility.
OBJECTIVES/HYPOTHESIS: The vestibular autorotation test (VAT) examines responses to active head oscillations at frequencies between 2 and 6 Hz in the horizontal and vertical planes while the subject is fixating a visible target. At these frequencies, the vestibulo-ocular reflex (VOR) is the main source of eye movement for ocular stabilization, although other visual and somatosensory information interacts with the response. Because the neural mismatch theory places emphasis on multimodal sensory interactions as the cause of motion sickness, using the VAT, which measures eye movements resulting from vestibular, visual, and, to a certain extent, proprioceptive information and depends on the conscious participation and cooperation of the subject, could be of advantage in evaluating individuals with differing susceptibility to motion sickness. The purpose of the present study was to evaluate high-frequency VOR parameters in seamen at the two extremes of the seasickness susceptibility scale. STUDY DESIGN: Cross-sectional, parallel-group design. METHODS: Participants in the study were 35 healthy male volunteers aged 18 to 23 years, of whom 20 were highly susceptible to seasickness and 15 were nonsusceptible. The vestibulo-ocular reflex was evaluated by the VAT at frequencies ranging from 2.0 to 5.9 Hz. RESULTS: The lag of the vertical phase was significantly higher in the susceptible group. A significant interaction was also found between group and frequency, the vertical phase being significantly higher in the 3.9- to 5.9-Hz range. Although no group effect was detected for the lag of the horizontal phase, there was a significant interaction between group and frequency, the horizontal phase being higher in the susceptible group at 5.5 and 5.9 Hz. No significant group differences were found for horizontal or vertical gain. CONCLUSIONS: The present findings support the contention that the VAT, which measures eye movements resulting from multimodal vestibular, visual, and, to a certain extent, proprioceptive information and depends on the conscious participation and cooperation of the subject, may produce different results in subjects at the two extremes of the seasickness susceptibility scale. Despite the statistical differences that were found, VAT measurements could not be used for practical purposes to categorize individual motion sickness susceptibility.
Adolescent↗
Long-term fat preservation.
The injection of autologous free fat obtained by suction-assisted lipectomy for the correction of soft tissue defects is a common procedure in plastic surgery. However, unpredictable partial absorption of the injected fat often necessitates repeated harvesting and injection. Fat preservation for future re-injection is indicated to avoid repeated fat harvesting procedures. A previous study has shown that fat obtained by suction can be preserved by freezing for at least 2 weeks. The purpose of the present study was to investigate the effect of freezing autologous free fat for 7 months on the take of the fat graft. Human fat obtained by suction-assisted lipectomy was centrifuged and stored in a domestic refrigerator at -18 degrees C for 7 months. After thawing, the fat was injected into the scalp of 10 nude mice, which served as the study group. In the control group (n = 10), fresh fat was injected. Fifteen weeks later, the fat grafts were dissected out. Volumes, weights, and histological parameters were compared between the groups. The injected fat survived in both the study and the control groups but the histological parameters were significantly inferior in the frozen fat. The weight of the frozen fat was also significantly less compared with the fresh fat. The volume of the frozen fat was inferior but not significantly. Based on this in vivo experiment, it is suggested to refrain from using fat that has been frozen for 7 months or longer. The longest period and the optimal conditions for fat preservation should be further investigated.
Adipose Tissue↗
The effect of lidocaine and adrenaline on the viability of injected adipose tissue--an experimental study in nude mice.
Adipose tissue injection as a free graft for the correction of soft tissue defects is a widespread procedure in plastic surgery. The main problem in achieving long-term soft tissue augmentation is partial absorption of the injected fat, and hence the need for over-correction and re-injections. Lidocaine, used for local anesthesia, has been suspected as an inhibitor of growth of adipocytes in culture and slowing down glucose transport and lipolysis in adipocytes. In addition, reduced blood supply by local application of epinephrine was accused of having a negative effect on the graft. The purpose of this study was to examine the effect of local anesthesia, administered to the fat donor site, on the take of the injected fat. Human adipose tissue, obtained by suction-assisted lipectomy, was injected subcutaneously into the scalp of nude mice. Local anesthesia of the fat donor site consisted of a solution with 600 mg of lidocaine (0.06%) and epinephrine 1:1000000. In a control group, normal saline with no local anesthesia or epinephrine was administered to the donor site. One cc of fat was injected after centrifugation into each animal scalp. There were 10 animals in each group. The animals were sacrificed 15 weeks after the procedure. Graft weight and volume were measured, and histologic evaluation was performed. No significant differences were demonstrated between the groups in regard with the grafts' weight and volume and the histologic parameters investigated. In conclusion, local anesthesia solution, consisting of lidocaine and epinephrine, does not alter the take of fat grafts, and has no influence on the adipocytes viability.
Adipose Tissue↗