Kristal-Boneh E, Raifel M, Froom P, Ribak J. Heart rate variability in health and disease. Scand J Work Environ Heal th 199521 :85-95.Beat-to-beat fluctuations in heart rate (HR) or instantaneous HR is mainly determined by activity of the cardiac sympathetic and parasympathetic systems. Despite the need for standardization in methodology to facilitate the interpretation and coinparison of results, the data presented in this review clearly show that there are individual differences in heart rate variability (HRV) and that these differences partly reflect differences in the degree of parasympathetic and sympathetic stimulation of the heart. HRV and its spectral components can be easily and noninvasively assessed and call provide valuable information to the occupational physician. Measurements of HRV and the quantification of its spectral components are powerful predictors of cardiovascular morbidity and mortality. Therefore it may help assess the return to work of patients with ischemic heart disease. Studies in the workplace can also indicate the effects of various stresses of the work environment on such patients and even on asymptomatic workers. Key words occupation, review.For a long time the study of heart rate variability (HRV) was confined to the laboratory. However, thanks to recent advances in microprocessor technology, the analysis of beat-to-beat variation has become possible also to the clinician. The increasing number of HRV investigations in the clinical and physiological literature emphasizes the value of HRV measures as a prognostic tool for the rapid and noninvasive assessment of the autonomic nervous function of the heart. Provided herein is an update of the current knowledge on HRV, in health and disease. Hearf rate variability -definifion and causesHRV is defined as spontaneous fluctuations in sinus rate due to internal and external body processes. It is usually measured as the standard (or average) deviation from the mean R-R intervals of all cardiac cycle lengths (R-R intervals for normal sinus beats) over a given period, most commonly 5 min. Beat-to-beat fluctuations in heart rate are mainly determined by the activity of the cardiac sympathetic and parasympathetic systems. Physiological experiments have demonstrated a correlation between cardiac nervous activity and immediate R-R interval changes (1-4). These studies form the basis for the examination of autonomic cardiac activity by HRV. The rate and variation of heart beats are the result of a complex interaction between sympathetic and parasympathetic efferent impulse activity in addition to the influence of sinus node pacemaker properties (5-7). The sinoatrial (S-A) node is directly and richly innervated by both sympathetic and parasympathetic (vagus) nerve fibers, which are continually active; the atrioventricular (A-V) node is less affected. Parasympathetic stimulation hyperpolarizes the S-A node, decreasing the rate of spontaneous firing and the cardiac rate. Sympathetic nerve endings, on the other hand, release norepinephrine, and th...

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The hypothesis of this study was that noise exposure level and job complexity interact to affect changes in blood pressure (BP) levels and job satisfaction over 2-4 years of follow-up. Results showed that among workers exposed to high noise, those with complex jobs showed increases in BP that were more than double shown by those with simple jobs. Under low noise exposure, there was a small increase in BP for workers with complex jobs but about a 3-fold increase in workers with simple jobs. The prevalence of elevated BP showed a similar trend. Job satisfaction increased among workers with complex jobs but was much less in those exposed to high noise. It was concluded that exposure to occupational noise has a greater negative impact on changes in BP and job satisfaction over time among those performing complex jobs. In contrast, job complexity had a clear beneficial effect for workers exposed to low noise.

The medical records of 1000 asymptomatic male air force personnel were examined retrospectively for the results of 15yearly-examinations of urinary sediment. The study covered the, period 1968-82, beginning with the subjects aged 18-33 years. The cumulative incidence of two to four or more red blood celis per high power field found at one or more examinations was 38-7% after an average of 12-2 yearly examinations per person. In 161 subjects two to four or more red blood cells per high power field were found at two or more yearly examinations within a five year period.Intravenous pyelography in 58 cases disclosed asymptomatic nephrolithiasis in six. Cystoscopy performed in 11 cases identified one patient with urethritis, one with a vesical calculus, and one with transitional cell carcinoma of the bladder. Two years before diagnosis the patient with carcinoma had had a single transient finding of 10-12 red blood cells per high power field which was not investigated further. Cystoscopy was performed after an episode of macroscopic haematuria. Renal biopsy in one subject with recurrent microhaematuria and trace proteliirla disclo*ed focgl glomerilonephritis. None of the remaining subjects with microhaematuria developed hypertension or proteinuria, and at the end of the study period all were active and free of urinary symptoms.The observed cumulative incidence of urological neoplasms at 15 years (0 1 %) was consistent with that expected in Israeli men aged 18-40 (009%). Hence microhaematuria detected during a screening examination probably should not be regarded as a specific sign of a significant lesion and does not of itself warrant urological investigation in adults aged 40 or less.

Cherkassky T, Oksenberg A, Froom P, Ring H: Sleep-related breathing disorders and rehabilitation outcome of stroke patients: A prospective study. Am J Phys Med Rehabil 2003;82:452-455. Objective: Sleep-related breathing disorder (SRBD) is more prevalent in stroke patients than in age-and sex-matched controls, but the relationship between SRBD, functional levels at admission, and subsequent recovery is unclear. We evaluated patients after a first stroke to determine the prevalence of SRBD and the influence of SRBD on the recovery of discharge functional status after a rehabilitation program.Design: In a prospective study, 30 stroke patients were studied by continuous overnight pulse oximetry during sleep for the presence of desaturation events (fall of arterial saturation of Ͼ4% from the baseline). The Respiratory Disturbance Index was defined as number of desaturations per hour of sleep. Functional assessment was done at admission using the FIM™ instrument. The patients were asked about total hours of sleep and the presence or absence of habitual snoring before and after the stroke. The outcome measure at discharge was the FIM score.Results: On linear regression, after including the FIM score at admission, in the model, the Respiratory Disturbance Index score was negatively correlated with the FIM gain (coefficient, Ϫ0.635 Ϯ 0.27; P ϭ 0.025), and together, the variables explained 20.9% of the total variance (adjusted r 2 ). All patients with an admission FIM score of Ն70 (only mild functional impairment) had a good outcome (FIM score of Ͼ100 at discharge). However, only two of six of those with FIM scores of Ͻ70 with SRBD (defined as a Respiratory Disturbance Index score of Ͼ10) had significant improvement (Ն30 points), whereas this occurred in seven of nine of those without SRBD (prevalence ratio, 0.43; 95% confidence interval, 0.13-1.40; P ϭ 0.085) Conclusions: Even after adjusting for the admission functional status, the presence of hypoxic events during sleep predicts a poorer recovery, especially in stroke patients with poor function at admission.