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Biomedical subjects

J Ribak

Publications and source records attributed to J Ribak.

At least 109 records · Page 6Linked to original sources
PubMed1988

Air accidents, pilot experience, and disease-related inflight sudden incapacitation.

The epidemiology of sudden death, the etiology of inflight sudden incapacitation, and the influence of pilot age and experience on air accident rates are reviewed in order to determine the aeromedical emphasis needed to minimize accidents. Sudden deaths in men over age 35 are nearly all due to coronary artery disease, whereas in those under 35 years they are mostly due to hypertrophic cardiomyopathy. The incidence of fatal accidents from human error is, however, far greater than that from physical illness. Since inexperienced pilots have a 2-3 times increased incidence of mishaps due to pilot error, the estimated risk of disease related in-flight sudden incapacitation should be balanced by consideration of pilot experience. Therefore, it may be preferable to grant waivers to experienced pilots with an increased incidence of disease-related inflight sudden incapacitation than to replace them with novices. We conclude that overly strict medical criteria may paradoxically increase accident rates.

Accidents, Aviation↗
PubMed1988

Left anterior hemiblock in otherwise healthy pilots.

We studied 15 male pilots with left anterior hemiblock (LAH) and compared them to 15 age-matched controls. Exercise testing was normal in all 15 pilots with LAH. There was no significant difference in the measurements of cardiac geometry in the 15 pilots compared to the controls, with valve thickness, mitral valve posterior motion and septal thickness also being similar in the two groups. The pilots remained asymptomatic and on active flying duty during the mean follow-up period of 52 +/- 8 months. We conclude that LAH is a benign condition in young asymtomatic men.

Adult↗
PubMed1987

Usefulness of echocardiographically determined mitral leaflet motion for diagnosis of mitral valve prolapse in 17- and 18-year-old men.

Mitral leaflet motion during systole was studied by echocardiography in 102 healthy young men. Mean posterior maximal leaflet motion was 2 +/- 1 mm behind the CD line on 2-dimensionally (2-D) directed M-mode examination. On the apical 4-chamber cross-sectional view a mean area of 0.34 +/- 0.24 mm2 was contained by the mitral leaflets above the plane of the mitral anulus. Elevated values on the M-mode view (greater than or equal to 4 mm) compared with the 2-D 4-chamber view (greater than or equal to 0.70 mm2) were discordant, with 90% (18 of 20) of the elevated values found in 1 view only. Thus, there is a wide spectrum of mitral leaflet motion in asymptomatic young men. The value of the echocardiogram in diagnosis of mitral valve prolapse is questionable because any cutoff point between normal and abnormal is arbitrary and the degree of motion has not been shown to correlate with morbidity or mortality.

Adolescent↗
PubMed1987

Serum cholesterol levels three years before and after viral hepatitis.

The serum cholesterol levels 3 years before and 3 years after an acute episode of hepatitis in 12 men aged 21-36 were compared to those in 22 age-matched controls. Serum cholesterol increased significantly during the acute icteric phase of the illness and remained elevated for 3 years after recovery. We conclude that cholesterol metabolism does not return to the prehepatitic state even 3 years after recovery.

Adult↗
PubMed1987

Non-malignant chest x ray changes in patients with mesothelioma in a large cohort of asbestos insulation workers.

To assess the prevalence of non-malignant chest x ray abnormalities in cases of mesothelioma 184 cases of mesothelioma (72 pleural and 112 peritoneal) which had occurred in a cohort of asbestos insulation workers followed up since 1967 were studied. Chest x ray films of satisfactory quality, on which the presence or absence of non-malignant radiological changes indicating interstitial pulmonary fibrosis or pleural fibrosis or both, could be assessed with a high degree of certainty were available. In some cases (20% for pleural mesothelioma, 11.6% for peritoneal mesothelioma) non-malignant radiological changes were not radiologically detectable. Parenchymal interstitial fibrosis (small irregular opacities) only was found in a proportion of cases (25.4% of pleural mesotheliomas, 12.5% of peritoneal mesotheliomas). Pleural fibrosis only was detected in 17% of cases of pleural mesothelioma and 27% of cases of peritoneal mesothelioma. Most patients had both parenchymal and pleural fibrosis. Although these results tend to indicate that in peritoneal mesothelioma the proportion of pleural fibrosis is significantly higher, these findings might have been due to the fact that in most cases of pleural mesothelioma non-malignant changes were interpreted in one hemithorax only. In 46 cases (21 pleural, 25 peritoneal) in which sufficient lung tissue was available histopathology of lung parenchyma indicated the presence of interstitial fibrosis; in 20 (43.5%) of these the chest x ray film had been read as negative. Thus the absence of radiologically detectable small opacities on the chest x ray film does not exclude the existence of interstitial pulmonary fibrosis in cases of mesothelioma among insulation workers. With lower levels of exposure (such as in family contacts of asbestos workers) it is conceivable that mesothelioma might occur in the absence of interstitial pulmonary fibrosis.

Asbestos↗
PubMed1987

Predictive value of premature ventricular contractions on the resting electrocardiogram for ventricular arrhythmias on 24 hour monitoring in asymptomatic young adults.

Between the years 1981-1984, 89 air-personnel, ages 18-45 years, underwent 24-hour ambulatory ECG monitoring at the Israel Air Force Aeromedical Center due to an incidental finding of one or more premature ventricular contractions (PVCs) on the resting supine 12-lead ECG. Complex ectopic arrhythmias (bigemini, trigemini, couplets, ventricular tachycardia, R on T phenomenon, or multifocal patterns) were observed during monitoring in 1.4% of 138 control subjects without PVCs, in 22% of those with 1 to 3 PVC X min-1 and in 68% of those with 4 or more PVC X min-1 on the resting ECG. Altogether 39(44%) of the 89 subjects with PVCs on the resting ECG had complex ectopic rhythms on monitoring. Of the 43 subjects with available follow-up data, 3 (7%) reported bouts of dizziness and light headedness which coincided with complex ectopic rhythms. In one of these three subjects, the bouts of dizziness coincided with runs of ventricular tachycardia during exercise testing.

Adult↗
PubMed1987

Low back pain in the AH-1 Cobra helicopter.

Pilots of the AH-1S helicopter maintain a vertical sitting position in the gunner's position (front seat), whereas in the pilot's seat (rear), they lean forward and to the left in order to operate the controls. A cross over study with pilots flying alternately in the front and rear positions was used to assess the effect of crew position on the prevalence of low back pain during flight. In the pilot's seat, there was an increased prevalence of pain (72.2%, 13/18 versus 55.6%, 10/18); the onset of pain was quicker than experienced in the gunner's position (64.3%, 9/14 versus 7.1%, 1/14, p less than 0.001); and the intensity was greater (85.7%, 12/14 versus 7.1%, 1/14, p less than 0.001). We conclude that posture is an important component of the low back pain experienced by helicopter pilots during flight.

Adult↗
PubMed1987

Visual acuity, corrective lenses, and accidents in helicopter pilots.

The visual acuity of 38 helicopter pilots experiencing serious air accidents was compared to that of a control group of 72 pilots, matched for age, aircraft, and hours of flight. Decrease in visual acuity was divided into two groups: 1) minor decreases in vision up to 20/25 (not requiring corrective lenses); and 2) visual acuity of 20/30 or less with correction to 20/20. Minor decreases in visual acuity were found in 23.7% (9/38) of those in the accident group compared to 25.0% (18/72) in the control group. There were more pilots in the control group who needed corrective lenses (12.5% (18/72) versus 2.8% (1/38), p less than 0.07). We conclude that helicopter pilots with corrective lenses or minor uncorrected decreases in visual acuity are not at increased risk for serious air accidents.

Accidents, Aviation↗
PubMed1987

Asymptomatic microscopic hematuria in pilots.

Pilots were examined in order to determine whether the cumulative incidence or point prevalence of asymptomatic microscopic hematuria is associated with air duty. The cumulative incidence of recurrent microscopic hematuria over a 12-15-year period was 11.3%(17/151) in fighter pilots, 10.0%(8/80) in helicopter pilots, and 13.8% (11/80) in transport pilots. Similarly, the point prevalence of microscopic hematuria in those who had flown the day prior to the urinalysis was no higher than found in the control group. We conclude that air duty does not cause microscopic hematuria either chronically or during the day after the stress of air flight.

Adult↗
PubMed1987

Spondylolithesis in pilots: a follow-up study.

There were 21 pilots followed for 12-131 months in order to determine the natural history of spondylolithesis (SLL). Of these 21, 16 had follow-up X-ray examinations, and only 1 was found with significant progression of the posterior vertebral displacement. Of the 12 pilots with SLL and low back pain (LBP), 4 had recurrent single episodes of acute LBP, but all remained active and continued to fly over the follow-up period. None of the 9 pilots who had SLL discovered on routine X-ray examination developed LBP over the follow-up period. We conclude that pilots with SLL can continue to fly with minimal risk of morbidity and loss of flight time.

Adult↗
PubMed1987

The predictive value of the body mass index for systolic blood pressure 12-15 years later in young air force personnel.

The records of 719 male air force personnel, aged 18-30 in 1968, were searched for the results of the systolic blood pressure (SBP), and height and weight examinations at entry in 1968 and after 12-15 years follow-up. The body mass index (BMI = weight/height2) was calculated and an elevated value was defined as one in the upper quintile. An elevated blood pressure, defined as an SBP greater than or equal to 140 mm Hg, was found on follow-up in 4.7% of the entire cohort, in 6.0% (4/67) of those with an elevated SBP and a normal BMI at entry, in 10.2% (12/117) of those with a normal SBP and an elevated BMI at entry, and in 20.0% (7/35) of those with both elevated BMI and SBP greater than or equal to 140 mm Hg at entry. Of those with a normal SBP and BMI at entry, 2.2% (11/500) had an elevated SBP on follow-up. We conclude that BMI in young men can predict SBP 12-15 years later, and that this predictive value is at least as high as that of the resting blood pressure.

Adult↗
PubMed1987

Efficacy of transdermal scopolamine against seasickness: a 3-day study at sea.

Transdermal scopolamine has been reported to provide protection against motion sickness, both while sailing at sea (7-8 h) and under experimental conditions. In this study, we tested the efficacy of transdermal scopolamine and evaluated its side effects during a 72-h cruise at sea. We tested 38 male volunteers, 20-25 years old, who were located on a 3000-ton vessel. The presence of seasickness, defined by Graybiel's diagnostic criteria, was used to calculate percent protection. When sickness was considered as malaise II or more, the drug provided 74, 73, and 39% protection during the three sailing days, respectively. There were no significant differences in the magnitude of the side effects reported by experimental and placebo groups. We conclude that transdermal scopolamine's efficacy against seasickness during a 3-day cruise was not associated with significant side effects and, therefore, we find the drug suitable for long-term use by sailing crews.

Administration, Cutaneous↗
PubMed1986

Electrolyte changes in mesothelioma.

Little has been reported concerning electrolyte changes among patients with mesothelioma. Two studies have suggested that hyponatraemia is particularly common among them and should lead to suspicion of inappropriate secretion of antidiuretic hormone in those patients (Perks et al. 1979; Siafakas et al. 1984). We reviewed serum electrolyte changes in three groups of patients: 48 cases of pleural mesothelioma, 89 of peritoneal mesothelioma, associated with asbestos exposure, and 149 of asbestosis. Five of 48 (10.4%) patients with pleural mesothelioma, 17 of 89 (19.1%) with peritoneal mesothelioma, and 23 of 149 (15.4%) patients with asbestosis without mesothelioma, had hyponatraemia. No statistically significant difference among the groups was found. These findings do not support the proposal that hyponatraemia is unusually common when mesothelioma is present, at least not among patients whose neoplasms are related to asbestos exposure.

Asbestosis↗
PubMed1986

The effect of age on the prevalence of asymptomatic microscopic hematuria.

The medical files of a sample of men who had been followed by annual examinations from 1968 through 1978 were selected, using a random number sequence from the records of the Israel Air Force. One group of 430 men, ages 21-23 at entry, and a second group of 264 men, ages 25-28 at entry, were studied. The results of the urinalysis at entry and after ten years of follow-up were recorded. The point prevalence of all degrees of microhematuria increased significantly with age in both groups. One to three or more red blood cells (RBCs) per high-power field (HPF) were found in 3.5% of the subjects ages 21-23 at entry and in 14.2% in the same subjects ten years later (P = 0.001). Similarly, one to three or more RBCs per HPF were found in 4.9% of men ages 25-28 at entry and in 11.7% of the same subjects ten years later (P = 0.001). The authors conclude that age needs to be taken into consideration in drawing the line between physiologic and pathologic microhematuria.

Adult↗
PubMed1986

Hazards of lung biopsy in asbestos workers.

An investigation into the problem of the frequency and hazards of lung biopsy in asbestos workers was performed in two ways. The first study was into the frequency of lung biopsy among 2907 long term asbestos insulation workers in 1981-3 and the second was into the frequency of fatal complications of lung biopsy in 168 deaths from asbestosis among 2271 consecutive deaths of asbestos insulation workers 1967-76. Only 25 (0.9%) of the 2907 asbestos insulation workers reported having had either an open lung biopsy, a needle biopsy, or a transbronchial biopsy. Seven (24%) of these men suffered difficulties as a result of the biopsy. Lung biopsies had been performed on 14 of the 168 workers who died of asbestosis. Three (21%) of these 14 patients had died within 30 days of biopsy as a direct result of the procedure. In most cases there is no need for lung biopsy to establish a diagnosis of asbestosis; generally, it may be defined by history of exposure, clinical and radiological findings, and other well established non-invasive diagnostic procedures. Certainly, legal and compensation recommendation for biopsy should be considered with the possibility of death in mind. If biopsy is performed precautions should be taken, including adequate observation in hospital.

Asbestosis↗
PubMed1986

Prevalence of postural T wave changes in mitral valve prolapse: a quantitative study.

The abnormal ECG T wave changes associated with mitral valve prolapse (MVP) were studied and quantitated in a group of 36 asymptomatic individuals with MVP and compared with a 27-member control group. The mean frontal plane T wave axis shifted markedly leftward on standing, with T wave axis less than or equal to 0 degrees in 16 (44%) of the subjects with MVP vs. only 2 (7.4%) of the control group, while the QRS-T angle widened to more than 60 degrees in 18 (50%) of those with MVP. Marked left axis deviation of the T wave on standing with T wave axis less than or equal to -30 degrees was found only in subjects with MVP, and their QTc interval was longer, P less than 0.05. In 11 subjects with mitral valve bowing or rounding on the echocardiogram (i.e., less than 2 mm posterior mitral valve displacement), intermediate grades of T wave axis shifts were seen.

Adolescent↗
PubMed1986

Central serous retinopathy (choroidopathy) in pilots.

The clinical charts of pilots in the Israeli Airforce were reviewed retrospectively for evidence of central serous retinopathy (CSR). There were 14 pilots with documented CSR identified, with an incidence of 1.3 per 1000 per year. Of 6 pilots who had recurrent attacks, 5 had a decrease of visual acuity during the initial attack to at least 20/30 in the affected eye. On the other hand, in those with visual acuity no worse than 20/25, only 1 of 7 had recurrent attacks (p less than 0.05). We conclude that CSR is a common condition in pilots, and that visual acuity during the initial attack can predict those who will have recurrent disease.

Adult↗