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Background: The United States Air Force (USAF) air evacuation system in the Western Pacific frequently transports unstable angina patients on fixed wing aircraft over long distances to reach definitive cardiologic and cardiothoracic capabilities. This study begins to answer the question: Does the transfer of unstable angina (i.e., crescendo angina or rest angina) patients over long distances adversely affect the overall outcome of such patients?, Methods: A case series study was conducted by obtaining a list of urgent and priority unstable angina patients from the Pacific theater from January 1992 through December 1996. Each of these patients' inpatient records were reviewed for cardiac catheterization (cath) result, ejection fraction (EF), previous cardiac history, angioplasty (PTCA) procedures, coronary artery bypass graft (CABG) surgery, and whether a patient had congestive heart failure (CHF), myocardial infarction (MI), death or other complications on this admission., Results: Of the 59 records reviewed, 61% (36/59) had coronary artery disease (CAD) of at least one vessel greater than 90% occlusion, 31% (18/59) had PTCA, 24% (14/59) had a CABG, 5% (3/59) had CHF, 3% (2/59) had an MI, 24% had some type of a complication, and 1.7% (1) died on this admission., Conclusion: Patients with significant CAD seem to tolerate air transport well with relatively few complications considering the overall morbidity and mortality associated with the diagnosis of unstable angina.

Background: Recent investigation into the push-pull effect (PPE), the reduction of +Gz tolerance when preceded by less than +1 Gz, has focused on centrifuge studies to demonstrate the presence of adverse cardiovascular responses. Maneuvers found to cause the Push-Pull Effect (PPEM) have not been studied previously in U.S. Air Force (USAF) fighter aircraft. The frequency of and extent to which PPEMs are performed in fighter aircraft are unknown., Methods: Head-up display (HUD) videotapes from F-15 and F-16 air combat training missions were reviewed for the presence of PPEMs. The frequency of engagements containing PPEMs and the magnitude of the Gz profiles were noted., Results: PPEMs were found in 11 to 67%, of engagements reviewed, depending on the nature of the training mission, with an overall average of 32%. The PPEMs that were observed contained segments of less than +1 Gz, ranging on average from 0.0 to 0.5 Gz for an average of 3.5 to 5 s duration., Conclusions: PPEMs are present in air combat training missions performed by today's USAF fighter aircraft and represent an operationally significant source of risk for accidents. These findings support continued research into the physiologic response to PPE and the development of countermeasures.

Background: A recent Canadian Forces CF-18 Hornet aircraft accident has focused interest on the push-pull effect (PPE). PPE has not previously been identified in U.S. Air Force (USAF) G-Induced Loss of Consciousness (G-LOC) Accidents. The presence of maneuvers known to cause the push-pull effect (PPEMs) that lead to G-LOC accidents suggests that PPE is operationally significant and is a potential cause of G-LOC accidents., Methods: USAF accident reports where G-LOC was found to be causal were reviewed for indications of a PPEM immediately prior to the G-LOC. Terminology in the narratives was used to indicate a PPEM in the accident sequences., Results: In 3 of 24 mishaps, the presence of a PPEM was highly probable, while another 4 mishaps were found to have a probable association with PPEMs. The probable presence of PPEMs represents a significant percentage (12.5-29%) of USAF G-LOC accidents., Conclusion: USAF G-LOC accident reports contained descriptions that indicated the presence of PPEMs in accident sequences. This finding suggests that the PPE is an operationally significant source of risk for accidents in USAF high-performance aircraft.

Although the growth of managed care is having a significant impact on hospitals, organizational response to managed care remains fragmented. We conducted a survey of 83 hospitals nationwide that indicated that most hospitals now have at least one person devoted to managed care initiatives. These individuals, however, often spend most of their time on current issues, such as contracting with managed care organizations and physician relations. Concerns for the future, such as network development and marketing, although important, receive less immediate attention form these individuals. Hospital managed care executives must take a more proactive role in long range managed care planning by collaborating with managed care organizations and pharmaceutical companies.

Unlabelled: We compared the brain cancer risk of male United States Air Force (USAF) aircrew (37 cases) with nonflying Air Force personnel (193 cases) between 1970 and 1989., Methods: Incident brain cancer cases for both aviators and nonflying USAF personnel were obtained from USAF hospitalization records. Age, race, and calendar time matched controls were randomly selected for each case from the remaining USAF cohort. We estimated brain cancer risks using conditional logistic regression models., Results: Initially, we observed a statistically significant brain cancer excess for USAF aircrew compared to nonflying USAF personnel (Odds Ratio [OR] = 1.77, 95% Confidence interval [95% CI] 1.17-2.68). However, following adjustment for senior military rank, a socioeconomic status indicator, the USAF aircrew brain cancer risk was markedly reduced (OR = 1.22, 95% CI 0.76-1.95), demonstrating that much of the previously observed USAF aircrew brain cancer risk was attributable to factors other than flying., Conclusion: The results of this investigation indicate that flying is not an important brain cancer risk factor, at least for USAF aircrew. The positive relationships observed in other studies between commercial aircrew and brain cancer risk may have been confounded by social class differentials.

Unlabelled: We compared the cancer incidence of male United States Air Force (USAF) aircrew (342 cancers, 532,980.97 man-years) with non-flying Air Force officers (827 cancers, 1,084,370.08 man-years) between 1975-89., Methods: Incident cancer cases for both aviators and non-flying officers were obtained from USAF hospitalization records. Age-adjusted standardized incidence ratios (SIR's) were calculated for aircrew using data from the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) program. Aviator age-adjusted cancer rate ratios were also obtained using non-flying officers as an internal comparison group., Results: We observed statistically significant excesses of aircrew cancers for all sites, testis, and urinary bladder. All other aviator cancer classifications were not significantly different from the comparison cohort; most notably, cancers of the colon and rectum, skin (both malignant melanoma and non-epithelial), brain and nervous system, Hodgkin's Disease and leukemias., Conclusion: Previous studies of commercial pilots that demonstrated excesses of these cancers may have been biased by the use of external comparison groups. We used an internal comparison population to reduce selection bias, information bias and confounding. From these data we detected notable excess aircrew cancer risk for cancers of the testis, urinary bladder, and all sites combined.

U.S. Air Force (USAF) regulations do not recommend the routine movement of obstetrical patients greater than 34 weeks gestation. However, U.S. Department of Defense and embassy physicians throughout Europe continually request aeromedical movement of obstetrical patients greater than 34 weeks gestation. Therefore, a year-long prospective review of obstetric patient movement within the military aeromedical system in Europe was undertaken to evaluate the need for and safety of transporting pregnant women over 34 weeks gestation. Civilian studies demonstrate the safety of transporting these patients, but these studies generally address short-range transport by helicopter. By contrast, the USAF operates a high-volume, long-range aeromedical evacuation system with large fixed-wing aircraft. Of the 13,095 patients reported for military aeromedical movement within the study time frame, 329 patients were uneventfully airlifted for obstetrical reasons. This study suggests that long distance movement by fixed-wing aircraft of obstetric patients at any gestational age can be done safely in the USAF military aeromedical system.

Background: Physicians were involved in the development of aeromedical evacuation (medevac) and flight surgeons flew as crewmembers on the first U.S. military medevac flights. However, since World War II flight surgeons have not been routinely assigned to operational medevac units. The aeromedical literature addressing the role of physicians in medevac is controversial. Recent contingencies involving the U.S. Air Force (USAF) have required the augmentation of medevac units with flight surgeons., Recent Changes in the European Theater: Beginning in 1992, the United States Air Forces Europe (USAFE) assigned three flight surgeons to the medevac squadron. Between 2 February 1993 and 24 March 1994 USAFE moved 241 patients on 29 missions out of the former Yugoslavia--most of these missions had a flight surgeon on the crew. Because advance medical information on the status of these patients is often nonexistent, the presence of a physician on the crew proved life-saving in some instances. In peacetime operations, there has been a recent trend in the European theater for the USAF to move more unstable patients., Observed Benefits of Physicians in Medevac: Dedicated medevac flight surgeons have proven to have the specific experience and training to perform effectively in the role of in-flight medical attendant. In addition, they are effective in negotiating with referring physicians about the urgency of movement, required equipment, the need for medical attendants, etc. These flight surgeons also provide medical coverage of transiting patients in the Aeromedical Staging Flight (ASF), thus providing needed continuity in the medevac system., Conclusion: Dedicated medevac flight surgeons fill a unique and valuable role in medevac systems. Agencies with medevac units should consider assigning flight surgeons to these units.

United States Air Force regulations currently do not recommend the routine movement of recently stabilized patients diagnosed with acute myocardial infarctions. However, U.S. Department of Defense and embassy physicians throughout Europe continually request aeromedical movement of these patients. Therefore, a year-long prospective case review of acute myocardial infarction (AMI) patient movement within the military aeromedical system in Europe was undertaken to evaluate the need for and safety of transporting these patients. This case review, combined with the literature, suggests that recently stabilized AMI patients, with appropriate pre-flight preparation and in-flight care, can tolerate exposure to the stresses of flight and can be safely airlifted.

Spatial disorientation (SD) continues to contribute to a fairly constant proportion of military aircraft accidents. The U.S. Air Force (USAF) fielded a new accident investigation reporting form in July 1989, which for the first time specified Type I SD, Type II SD, and Type III SD as possible causes of aircraft accidents. Of a total of 91 major accidents that occurred over the 2-year period beginning in October 1989, SD was rated as contributing significantly to 13 (14%). Coding for SD on accident investigation reporting forms was not consistent, however. Individual flight surgeons differed in their approaches to coding accidents as SD-related; other differences were noted between flight surgeons and pilots, and additional procedural differences resulted in inconsistent reporting over time. There is a consensus that SD represents a major problem in military aviation, but a scientific approach to this important problem would be facilitated if agreement could be reached on definitional and semantic issues.

Discussion of acceleration protection measures should be based on analysis of relevant accident data, including determination of high risk aircraft, G profiles, and pilot descriptions. There were 18 accidents (14 fatalities) attributed to G-induced loss of consciousness (G-LOC) in the United States Air Force (USAF) from 1982 through 1990. All 18 accidents occurred during single crewmember sorties, for an average rate of 2.1 per million single-seat flying hours (pmfh). The average G-LOC accident rate for 1982-4 was 4.0 pmfh, decreasing significantly to 1.3 pmfh for 1985-90. This decrease is associated with the USAF initiation of an anti-G-LOC training program. We reviewed accident records for G-LOC cofactor data and compared them to normal data for USAF pilots for age, height, weight, systolic and diastolic blood pressures, heart rate, total flying time, and aircraft-specific flying hours. Only for systolic blood pressure (higher) and aircraft-specific flying hours (shorter) were the mishap pilots significantly different from other USAF pilots. We found no evidence to support weight training vs. aerobic training, missed meals, or heat in causing G-LOC accidents. Thus the mishap pilots appeared to be a representative cross section of USAF pilots with respect to personal variables. More significant factors appeared to be G duration, G magnitude, use of G trousers, and experience in assigned aircraft.

In-flight incapacitation of a fully trained crewmember due to a serious underlying medical condition is a rather infrequent event. In order to delineate the extent and nature of the incapacitation problem we reviewed the data base at the Air Force Safety and Inspection Center for all incidents coded for incapacitation, preexisting disease, or other acute illnesses occurring during the 10 years between 1978 and 1987. During this period there were 23 in-flight incidents of incapacitation due to significant underlying medical conditions. In 11 of the incidents the incapacitation resulted in a loss of consciousness. Neurologic conditions were the most frequent cause followed by cardiovascular conditions. We calculated a rate of incapacitation as 0.19 per million aircrew flying hours.