The sleeping aviator--aeromedical disposition of Kleine-Levin syndrome

We present the case of an aviator with Kleine Levin syndrome (KLS). History, physical examination, and special studies presented confirm the diagnosis of this syndrome. Our patient presented as an atypical case of KLS with respect to the presenting symptoms and to frequency of the episodes (6 years apart). He exhibited only intense somnolence, easy arousability, photophobia, hyperacousis, and a voracious appetite. Following a complete medical work up we recommended that an applicant with such a classical case of KLS be disqualified as a crewmember; however, in cases such as that presented above a limited waiver may be considered. The aeromedical significance of this case is to reinforce the importance of screening candidates and seeking precise diagnosis of a past illness or hospitalization.

[Primary quality control in Israel Air Force clinics]

The practice of primary medicine within a military framework differs from that in the civilian environment in: accessibility, its consumers, obligations of the providers, involvement of the funder (the commanders), and ability to define and enforce professional guide lines. These differences influence the scope of medical service, as well as affect the methods and results of quality control. A system of quality control evaluation and feedback of military primary care in 16 Israel Air Force clinics was carried out by a team of experienced physicians using peer group review and according to a specially prepared protocol. Emphasis was placed on medical record assessment using obligatory markers of adequate medical evaluation and treatment. Identification of the population at risk, further medical training, and medical administration with a direct effect on the quality of medical treatment were also evaluated. 2 quality control surveys with feedback were carried out 6 months apart. The overall mean score was 81.66 +/- 7.16% at the first evaluation, increasing to 88.60 +/- 7.46% at the second (p < 0.01). The greatest improvements were in follow-up of population at risk (increasing from 68.4% to 86.4%, p < 0.025), training of medical teams, (from 75.7% to 87.5%, p < 0.05) and patient case management (from 79.4% to 85.1%, N.S.). Categories in which there was no improvement were medical records, recovery of old medical files and patient education. The categories in which there was improvement had a common denominator: "recognition of importance" and "provision of patterns" by headquarters. The quality control system was designed for routine use, and not as a research project.(ABSTRACT TRUNCATED AT 250 WORDS)

Coagulation activation following estrogen administration to postmenopausal women

We investigated coagulation system activation following estrogen treatment in 29 healthy postmenopausal women. Study participants received conjugated estrogens at 0.625 and 1.25 mg per day, and placebo for 3-month periods in a randomized crossover protocol. Blood samples were obtained on two consecutive days at the end of each treatment period for immunoassays of F1+2 and fibrinopeptide A (FPA), markers of factor Xa action on prothrombin and thrombin action on fibrinogen in vivo, respectively. Treatment with estrogens at a dose of 0.625 or 1.25 mg resulted in significant increases in mean F1+2 levels of 40 and 98%, respectively, and in mean FPA levels of 37 and 71%, respectively. The measurements of F1+2 were significantly higher in women receiving 1.25 mg of estrogen than 0.625 mg. We also observed significant declines in the levels of antithrombin III and total protein S antigen. Immunologic levels of protein C increased modestly at only the 1.25 mg estrogen dose level. These data indicate that low doses of oral estrogens (< or = 1.25 mg per day) frequently increase the amount of thrombin generated in vivo. Our observations may help to explain the increased thrombotic risk that has been observed with higher doses of this medication (> or = 2.5 mg).

Predicting increases in skin temperature using heat stress indices and relative humidity in helicopter pilots

We used measurements of heat stress in the cockpit of Bell 206 and 212 helicopters manned by a crew of two to predict changes in the skin temperatures of 50 pilots over a 1-h ground standby period. Cockpit wet bulb globe temperatures increased from 28.1 +/- 5.6 degrees C to 32.9 +/- 3.9 degrees C over the 1-h ground standby period. Skin temperatures increased from 34.7 +/- 1.1 to 35.4 +/- 1.1 degrees C, while heart rate increased from 79.4 +/- 9.6 to 82.6 +/- 9.8 bpm. Cockpit wet bulb temperatures explained 26.9% of the variance of the increase in skin temperature (P = 0.0002). Wet bulb globe temperatures, discomfort index and dry bulb temperatures did not improve the predictive value of wet bulb temperatures alone. Relative humidity was not significantly associated with the increase in skin temperature. We conclude that wet bulb temperatures predict changes in skin temperature as well as other heat stress indices. Furthermore, despite high cockpit temperatures, pilots experienced only minimal strain during the 1-h ground standby period. Extrapolation of our results to the effects on body temperature of higher degrees of heat stress and physical activity is unwarranted and deserves further study.

The failure analysis of composite material flight helmets as an aid in aircraft accident investigation

Understanding why a flying helmet fails to maintain its integrity during an accident can contribute to an understanding of the mechanism of injury and even of the accident itself. We performed a post-accident evaluation of failure modes in glass and aramid fibre-reinforced composite helmets. Optical and microscopic (SEM) techniques were employed to identify specific fracture mechanisms. They were correlated with the failure mode. Stress and energy levels were estimated from the damage extent. Damage could be resolved into distinct impact, flexure and compression components. Delamination was identified as a specific mode, dependent upon the matrix material and bonding between the layers. From the energy dissipated in specific fracture mechanisms we calculated the minimum total energy imparted to the helmet-head combination and the major injury vector (MIV) direction and magnitude. The level of protection provided by the helmet can also be estimated.

Primary Burkitt's lymphoma of the appendix

Appendicitis is a very rare presenting symptom of abdominal Burkitt's lymphoma. Only four cases have previously been identified in the literature, all of them males. This is the first reported case of a female as well as the youngest and is representative of the therapeutic considerations in this unusual manifestation of the disease.

Will they fly again? The probability of wounded military aviators returning to flying duty: a study of 70 cases

In this study, 70 Israeli Air Force aviators, most of them suffering from severe or moderately-severe injuries, were evaluated as to their potential to return to active flying duty. Of these, 59 (84%) were able to return to flying and 11 (16%) were permanently grounded. While 44 of 51 fighter aviators (86%) returned to flying, only 30 of them (59%) returned to fly fighters, and the rest were transferred to another type of aircraft. The roles of age and severity of injury were studied in detail and it was concluded that higher age and severe injuries prolong the convalescence period but do not prevent the aviator from returning to flying. Nine aviators were permanently grounded because of medical reasons. In each case a single injury could be demonstrated as the direct cause of their permanent grounding. All aviators were followed-up for 3 years after having returned to flying. It was concluded that an evaluation period of 2 years is sufficient to determine the long-term success of military aviators returning to flying.