Report of ejections in the Spanish Air Force, 1979-1995: an epidemiological and comparative study.

BACKGROUND: Ejection seats have saved many lives with more than 80% of pilots having survived an ejection. Nevertheless, ejection injuries are seen in all modern air forces. PURPOSE: An epidemiological study has been carried out on the 48 ejections made by the Spanish Air Force (SpAF) from 1979-1995. METHODS: From data facilitated by the Flight Safety Section of the SpAF Staff, by the Flight Safety Section of Squadrons, and from personal reports of pilots who survived ejections a form was created. Relationships between data concerning aeronautical parameters, pilot data and injuries have been found, and a comparative study was made between these results and data shown by air forces of other countries. RESULTS: Of 48 pilots who ejected, 7 died, 25 had severe injuries, 11 had minor injuries and 5 had no injuries. The reason for the ejections included 35 cases of technical failure, and 13 cases of human error. Of 43 surviving pilots, 23 were injured only at the egress phase, 1 1 only at landing, and 9 cases at both moments. None of the five pilots who ejected outside the ejection envelope were able to adopt the correct position. However, of 43 pilots who ejected within the envelope, 19 were seated in good position. Of 13 pilots who maintained control of the airplane, 9 were able to adopt a correct position. Of 35 pilots who effected the ejection without control of the aircraft, 25 were not able to achieve a correct seated position. CONCLUSIONS: The pilot position in the ejection seat, plane control, ejection inside the envelope, the pilot's training in how to assume the necessary body position at both egress and landing phases are determining factors for successful ejections.

Unexplained peripheral nervous conduction velocity variations in young military males.

Peripheral nervous conduction velocity has widely been used in neurology and traumatology. Recently, it has been added to diagnostic tests of several metabolic disorders since the myelin sheath is highly sensitive to internal environment variations. The catecholamines liberation induced by stress (physical and/or psychological) produces an important internal environment alteration characterized by an anaerobic metabolism increase causing acid catabolites generation. This paper describes an unexpected neurophysiological finding observed in the course of a wide aeronautical medicine research project. A homogeneous group (similar age, sex, diet, physical training and life-style) of young healthy military males (belonging to the Air Force Academy) (n = 60) showed statistically significant differences on peripheral nervous conduction velocity (both motor and sensory ways) among them and in front of reference values. Authors can not explain that observation decisively. They suggest both the different complexity of academic curriculum and the different oxygen consumption as possible factors that could provoke mentioned conduction velocity variations.

Influence of diet and physical exercise on plasma lipid concentrations in an homogeneous sample of young Spanish Air Force pilots.

This study evaluates the influence of diet and physical exercise on plasma lipid concentrations--total cholesterol (TC), triglyceride (TG), high density lipoprotein-cholesterol (HDL-C), and the TC:HDL-C ratio, in a homogeneous (age, sex and anxiety levels) group of young pilots divided into the following groups: A. uncontrolled diet and exercise programme; B. controlled diet and uncontrolled exercise programme; C. controlled diet and exercise programme (n = 90). The dietary intake was a typical Mediterranean diet, which was supervised by the Flight Surgeon. The exercise was based on a physical training programme for pilots, directed by the Physical Training Officer. The State-Trait Anxiety Inventory test was performed to evaluate the anxiety levels. This test was supervised by a psychologist. The results showed a marked difference in all the lipid parameters studied between groups with an ad libitum diet versus groups with a controlled diet, this difference being demonstrated by TC and TG concentrations lower in the group with a controlled diet, than in the group with an ad libitum diet. A difference in HDL-C concentrations and TC:HDL-C ratio was found between groups with regular physical training (high HDL-C concentration and low TC:HDL-C ratio) versus groups with unlimited exercise (low HDL-C concentrations and high TC:HDL-C ratio). No differences in the state and trait of anxiety were found among any of the groups. Nevertheless, all the pilots showed a considerable increase in their anxiety state over their own anxiety trait.

A case of hemidiaphragmatic paralysis after an anti-G suit failure.

This paper reports a case of left hemidiaphragmatic paralysis in an instructor pilot and his later recuperation. This incident was provoked by a failure in the anti-G suit, which remained inflated after the aircraft completed the maneuver that had originated the inflation. The spontaneous recuperation of both the respiratory functional test and the neurophysiological pattern are consistent with a Type II Seddon's axonotmesis of the phrenic nerve. Considering the short time of regeneration (6 months), this lesion must have involved the distal portion of the phrenic nerve.

Relation between flight hours and peripheral nervous conduction velocity.

The peripheral nervous system is highly sensitive to variations in the internal medium. A neurophysiological study (peripheral nervous conduction velocity) and an enzymatic study (catalase and glutathione-peroxidase) were performed in both instructor and student pilots. Pilots do not show the age-dependent decrease in the peripheral sensory nervous conduction velocity observed in non-pilot subject controls. The sensory conduction velocity (SCV) was significantly (p less than 0.01) increased when hours of flight experience increased, yielding a positive correlation (r = 0.6461; p = 0.0016). A significant (p less than 0.01) increase in the erythrocite catalase and glutathione-peroxidase activities were observed in pilots vs. controls. The present data suggest that a chronically increased oxygen consumption could be the reason for the increase in peripheral nervous conduction velocity observed in pilots.

Serum gastrin levels during pregnancy.

Serum Gastrin levels were measured by radioimmunoassay in serum samples taken from nongravid normal women and normal healthy pregnant volunteers who were divided into four groups according to gestation time. In nonpregnant control subjects the gastrin values found were 52.23 +/- 2.66 pg/ml. The gastrin levels observed from 5 to 15 and from 36 to 42 weeks of pregnancy are similar to the values of control subjects, whilst the gastrin levels found from 16 to 35 weeks are significantly lower. These results could help us to unravel the distressing problem of dyspeptic symptoms from 16th to 35th week of pregnancy.