Amit Assa

Role of Air-Medical Evacuation in Mass-Casualty Incidents—A Train Collision Experience

BACKGROUND On 21 June 2005, a passenger train collided with a truck near Revadim, Israel. The collision resulted in a multiple-scene mass-casualty incident in an area characterized by difficult access and a relatively long distance from trauma centers. A major disaster response was initiated by civilian and military medical forces including the Israeli Air Force (IAF) Search and Rescue teams. The air-medical evacuation from the accident site to the trauma centers, the activities of the airborne medical teams, and the lessons learned from this event are described in this report. METHODS A retrospective analysis of data gathered from relevant elements that participated in management, treatment, and evacuation from the accident site was conducted. RESULTS The accident resulted in 289 injured passengers and seven of the injured were killed. Six helicopters (performing nine sorties) participated. Helicopters evacuated trauma victims and aided in transporting air-medical teams to the site of the collision. Overall, 35 trauma victims (10 urgent) were evacuated by air to trauma centers. The length of time between the first helicopter landing and completion of the air evacuation was 83 minutes. The air-medical evacuation operation was controlled by the commander of the IAF Search and Rescue. Different crew compositions were set in real time. CONCLUSIONS Air-medical evacuation during this unique event enabled prompt transportation of casualties from the scene to trauma centers and provided reasonable distribution of patients between various centers in the region. This operation highlighted the necessity for flexibility in medical decision-making and the need for nonconventional solutions regarding crew compositions during management of an airborne evacuation in similar settings. Air-medical evacuation should be considered as a part of responses to mass-casualty incidents, especially when the site is remote or characterized by accessibility difficulties.

Pulmonary Artery Pressure in Young Healthy Subjects

BACKGROUND Pulmonary artery systolic pressure (PASP) is frequently measured noninvasively using transthoracic echocardiography. Normal values of PASP are based on studies performed in heterogeneous populations. The normal values of PASP in young healthy subjects are poorly defined. The aim of this study was to describe the distribution and clinical and morphologic correlates of PASP values in young healthy subjects. METHODS Echocardiography is routinely performed for aircrew candidates for the Israeli Air Force. All echocardiographic examinations performed between 1994 and 2010 in which tricuspid regurgitation was present, a prerequisite for echocardiographic PASP measurement, were collected. Subjects with morphologic abnormalities were excluded. PASP was calculated using the simplified Bernoulli equation, with right atrial pressure assumed to be 5 mm Hg. The associations between PASP and clinical and echocardiographic characteristics were studied. RESULTS Subjects were healthy young adults aged 17 to 29 years. Evidence of tricuspid regurgitation was found in 1,900 of 6,598 subjects. The estimated mean PASP value was 31.2 ± 4.5 mm Hg, and the upper 95th percentile was 34 mm Hg. In univariate analysis, PASP was correlated with left ventricular end-diastolic and end-systolic diameters. A multivariate linear regression model including age; diastolic blood pressure; echocardiographic measurements of aortic root, left atrial, and left ventricular end-diastolic diameters; and left ventricular mass explained only 7% of the variability in PASP. CONCLUSIONS PASP in young, physically fit subjects may be higher than previously reported in the general population and is poorly explained by age, blood pressure, and other echocardiographic parameters.

Natural history of mitral valve prolapse in military aircrew.

Objective: Mitral valve prolapse (MVP) is a common cardiac abnormality whose natural history differs among various patient populations. High-performance flight is associated with exposure to varying acceleration forces and strenuous isometric physical activity. The effect of the military flying environment on the natural history and progression of MVP is poorly defined. Methods: We evaluated a cohort which included all military aviators in the Israeli Air Force diagnosed with MVP. Medical records and echocardiographic studies of participants were reviewed for the development of clinical or echocardiographic complications. Results: The study population was comprised of 24 aviators, 14 of whom were high-performance aviators. Average follow-up was 23.5 years (total 563 person-years). Four aviators suffered from MVP-related complications including 2 cases of flail valve due to chordae rupture and 1 case each of newly diagnosed atrial fibrillation and infective endocarditis. Progression of asymptomatic mitral regurgitation was identified in 11 aviators. Conclusions: Military aviators with MVP may be prone to serious medical complications. A detrimental effect of high-performance flight on patients with MVP is suggested.

Acceleration forces and cardiac and aortic indexes in jet fighter pilots.

BACKGROUND Military jet fighter pilots are exposed to acceleration (+G(z)) forces which possibly influence various cardiac parameters. Several previous studies have evaluated the impact of exposure to acceleration forces on cardiac morphology and function, but these studies were not prospective and were either based on small samples or compared jet fighter pilots with pilots of low-performance aircraft. The purpose of this study was to evaluate the effect of acceleration forces on cardiac morphologic changes in jet fighter pilots. METHODS Routine echocardiography has been performed for jet fighter pilots since 2003. Medical records of all military jet fighter pilots who underwent echocardiography following 2003 were retrospectively evaluated. Of those, all jet fighter pilots who underwent an additional echocardiography prior to 2003 were identified. Echocardiographic parameters were recorded using M-mode and included left ventricular diameter at end systole and end diastole, interventricular septum thickness, thickness of the posterior wall, aortic root diameter and aortic valve opening, diameter of the left atrium, and left ventricular mass. Medical records of the subjects were evaluated for development of adverse events. RESULTS There were 72 subjects who underwent 2 echocardiographic examinations with a mean follow-up period of 8.92 yr. Subjects were 18-50 yr old at the time of the initial echocardiographic examination. All parameters evaluated by M-mode were not significantly changed from the baseline examination. No adverse events occurred during the follow-up period. DISCUSSION Findings of this study suggest that exposure to acceleration forces is not associated with cardiac and aortic morphologic changes.

Echocardiographic Evaluation and Follow-Up of Cardiac and Aortic Indexes in Aviators Exposed to Acceleration Forces

BACKGROUND Military jet fighter pilots are routinely exposed to acceleration (+Gz) forces. This recurrent exposure may influence various cardiac parameters. A few previous studies have evaluated the impact of exposure to acceleration forces on cardiac morphology and function, but these studies were mostly based on small cohorts, and subjects did not undergo baseline echocardiographic examinations before +Gz exposure. METHODS Ninety-six jet fighter pilots with high +Gz exposure underwent echocardiographic evaluation before and 7 to 12 years after repeated +Gz exposure. Echocardiographic parameters were recorded using M-mode echocardiography and included left ventricular diameter at end-systole and end-diastole, interventricular septal thickness, thickness of the posterior wall, aortic root diameter and aortic valve opening, diameter of the left atrium, and left ventricular mass. Medical records of the subjects identified were evaluated for the development of adverse events. RESULTS The average age at the time of the initial echocardiographic examination was 19.2 years. All subjects were healthy, without cardiovascular risk factors, and had no prior exposure to acceleration forces. The average flying period on jet planes at the time of follow-up examination was 1,812 hours. The mean follow-up period was 9.13 years. All parameters evaluated by M-mode echocardiography were not significantly changed from the baseline examination. No adverse events occurred during the follow-up period. CONCLUSIONS Exposure to acceleration forces has no significant impact on cardiac and aortic morphology.

Screening Echocardiography of Military Aircrew Candidates: Aeromedical Implications

Objectives: Cardiovascular evaluation has a significant aspect in the medical screening process of aircrew candidates. Echocardiography may identify asymptomatic cardiac abnormalities which can jeopardize the aviator and flight safety, as well as conditions which may progress and disqualify a trained aviator. We assessed the value of adding routine echocardiography to the aeromedical screening process. Methods: The study population consisted of 17- to 21-year-old healthy aircrew candidates. We retrospectively reviewed all routine echocardiographic studies performed during 1997–2008 at our clinic. Studies performed for a clinical indication were excluded. Results: A total of 2,657 echocardiographic studies were analyzed. 2,506 were considered ‘normal’ (94.3%). 151 studies (5.7%) demonstrated findings which required further consideration and were considered ‘abnormal’. Additional consideration included limitation to low-performance aircrafts (n = 22, 14.7%), prompt disqualification (n = 23, 15.3%), or further cardiovascular assessment (n = 106, 70% of ‘abnormal’ studies), which resulted in disqualification of 2 more candidates. Echocardiography resulted in disqualification of 0.94% of candidates, limitation to low-performance aircrafts in 0.83%, and need for follow-up in additional 1.54%. Conclusions: Echocardiographic screening affected aeromedical designation and follow-up decisions in 3.31% of candidates. Contribution of routine echocardiography is dependent on aeromedical policies. The Israeli Air Force policies regarding common findings are presented.

Inflammatory bowel disease in military aviators: 14 cases with return to flying duty.

Inflammatory bowel disease, such as ulcerative colitis or Crohns disease, is not a rare entity among military aviators. This relapsing inflammatory condition which may also affect extra intestinal organs can cause recurrent symptoms with considerable morbidity. The unpredictable nature of the disease, side effects of medications, and potential surgical procedures are obvious aeromedical concerns let alone the diseases extra-intestinal manifestations, some of which may result in sudden incapacitation. We present 14 military aviators who were diagnosed with inflammatory bowel disease and returned to flight duty after stabilization of symptoms. Mean follow-up period was 102 months (total of 1,429 months) without any adverse effects on flight safety. Only 4 aviators were grounded for a cumulative duration of 35 months during that period. We believe that because adequate disease control is readily feasible in most cases, safe return to flight duty within a short period is reasonable in uncomplicated cases.

Medical waiver for flying after microvascular decompression for hemifacial spasm.

BACKGROUND Microvascular decompression has become the treatment of choice for hemifacial spasm. Post-surgical symptoms of vestibular dysfunction may appear, but are mostly transient. The unique occupational demands of military aviators necessitate complete otoneurological evaluation after vestibular insults to allow safe return to flying duties. CASE REPORT We present a case of a military jet-fighter pilot who developed transient vertigo and disequilibrium after microvascular decompression for hemifacial spasm. Resolution of symptoms and complete recovery as documented by vestibular bedside and laboratory tests allowed us to grant the pilot full solo flying privileges.

Use of Adenosine Test for the Exclusion of Preexcitation Syndrome in Asymptomatic Individuals

Background: Resting electrocardiogram is a routine procedure for the identification of potentially fatal conditions, including preexcitation syndrome (PES). Intravenous adenosine is a sensitive and specific means of exposing inapparent pathways in such patients. Yet, it may not be sensitive when complete atrioventricular (AV) block is not achieved because a low dose of adenosine is used. We evaluated the yield of a high‐dose adenosine test that achieved complete AV nodal block for unmasking inapparent pathway in a healthy population.

Return to flight with multiple sclerosis: aeromedical considerations.

Multiple sclerosis (MS) is the most frequent demyelinating disease of the central nervous system, with versatile manifestations--relapsing-remitting or progressive--and an unpredictable course, with prognoses ranging from minimal neurological impairment to severely disabled. Disease modifying agents can minimize relapse rate and slow disease progression. Yet most patients suffer relapses and progression despite use of these agents. Several of the manifestations of MS may cause overall decrease in the performance of the aviator. These include cognitive impairment, fatigue, and depression. Episodes of spasms, dysarthria, ataxia, parasthesias, diplopia, and hemiplegia, as well as drug side effects may also affect flight. Seizures and episodes of vertigo may occur suddenly and result in in-flight incapacitation. We present our experience with two aviators with definite MS and a navigator with probable MS. The various manifestations of MS are specifically addressed with an emphasis on the aeromedical implications.