A novel rat-tail model for studying human finger vibration health effects

It has been hypothesized that the biodynamic responses of the human finger tissues to vibration are among the major stimuli that cause vibration health effects. Furthermore, the finger contact pressure can alter these effects. It is difficult to test these hypotheses using human subjects or existing animal models. The objective of this study was to develop a new rat-tail vibration model to investigate the combined effects of vibration and contact pressure and to identify their relationships with the biodynamic responses. Physically, the new exposure system was developed by adding a loading device to an existing rat-tail model. An analytical model of the rat-tail exposure system was proposed and used to formulate the methods for quantifying the biodynamic responses. A series of tests with six tails dissected from rat cadavers were conducted to test and evaluate the new model. The experimental and modeling results demonstrate that the new model behaves as predicted. Unlike the previous model, the vibration strain and stress of the rat tail does not depend primarily on the vibration response of the tail itself but on that of the loading device. This makes it possible to quantify and control the biodynamic responses conveniently and reliably by measuring the loading device response. This study also identified the basic characteristics of the tail biodynamic responses in the exposure system, which can be used to help design the experiments for studying vibration biological effects.

Vascular trauma of the hand - a systematic review

Hypothenar or thenar hammer syndrome (HHS) and hand-arm vibration syndrome (HAVS) are diseases caused by acute or chronic trauma to the upper extremities. Since both diseases are generally related to occupation and are recognised as occupational diseases in most countries, vascular physicians need to be able to distinguish between the two entities and differentiate them from other diagnoses. A total of 867 articles were identified as part of an Internet search on PubMed and in non-listed occupational journals. For the analysis we included 119 entries on HHS as well as 101 papers on HAVS. A professional history and a job analysis were key components when surveying the patient's medical history. The Doppler-Allen test, duplex sonography and optical acral pulse oscillometry were suitable for finding an objective basis for the clinical tests. In the case of HHS, digital subtraction angiography was used to confirm the diagnosis and plan treatment. Radiological tomographic techniques provided very limited information distal to the wrist. The vascular component of HAVS proved to be strongly dependent on temperature and had to be differentiated from the various other causes of secondary Raynaud's phenomenon. The disease was medicated with anticoagulants and vasoactive substances. If these were not effective, a bypass was performed in addition to various endovascular interventions, especially in the case of HHS. Despite the relatively large number of people exposed, trauma-induced circulatory disorders of the hands can be observed in a comparatively small number of cases. For the diagnosis of HHS, the morphological detection of vascular lesions through imaging is essential since the disorder can be accompanied by critical limb ischaemia, which may require bypass surgery. In the case of HAVS, vascular and sensoneurological pathologies must be objectified through provocation tests. The main therapeutic approach to HAVS is preventing exposure.

Diagnostic significance of cold provocation test at 12°C

In Germany, vibration-induced white finger (VWF) disease is accepted as an occupational disease (BK No. 2104 BKV), for which compensation may be paid provided that the sociolegal requirements are met in accordance with the list of occupational diseases that is valid at the time. A cold provocation test (thermometry, infrared thermography) is helpful in the diagnosis of VWF and we believe that it could contribute to the standardization of vascular assessment methods. In Germany, the approved degree of the decrease in earning power is downgraded as disease symptoms improve with time; therefore, insured individuals suffering from VWF are regularly reassessed every 1-3 years. In the context of such follow-up examinations and the assessment of reversibility of this disease, a standardized cold provocation test is of central importance. Currently, there is a lack of data that confirm the diagnostic value of this test. Further investigations on VWF patients to validate the use of the cold provocation test in obtaining sufficient data for determining the satisfactory diagnostic value of this test are required.

Test battery for assessing vascular disturbances of fingers

The diagnosis of vibration-induced white finger (VWF) is difficult, often relying on medical interview and history. The condition is characterized by an exaggerated vasoconstriction of digital arteries in response to cold. The complete closure of digital arteries is episodic and results in a characteristic blanching that is rarely observed by a clinician. Objective measurements of the response of the digital circulation to cold can assist in evaluating a patient for VWF. Finger systolic blood pressure (FSBP) following local cooling is a measure of cold-induced vasoconstriction in digital arteries and is an assessment of vasomotor tone. Low FSBPs following cooling are indicative of dysfunction. Finger skin temperature (FST) following hand cooling is a measure of cutaneous blood flow. The mechanism underlying the recovery of cutaneous blood flow following cooling is as yet not fully understood, but a delayed recovery is believed to arise from persistent vascular disturbances of the fingers or from a resulting in conflicting opinions concerning the utility of the measurements, a scarcity of comparable data from epidemiological investigations, and limited normative data to aid clinicians in decision-making. This review of evidence on which the tests are based is aimed at providing clinicians and researchers with an understanding of the factors that must be considered when conducting the tests, interpreting the results, and comparing results between different studies.

Factors influencing finger systolic blood pressure test for diagnosis of vibration-induced white finger

Finger systolic blood pressure (FSBP) measurement during finger cooling is a feasible method for the diagnosis of vibration-induced white finger (VWF). The standardization of the FSBP test is required. The final draft of an international standard for the measurement and evaluation of FSBP (ISO/DIS 14835-2) has been proposed in 2004. The aim of this review is to overview factors influencing the FSBP test and discuss some issues in the final draft. The FSBP test is a method of diagnosing VWF with reasonable sensitivity and specificity, although the sensitivity was relatively low in studies of mild VWF. The test results depend on cold provocation procedures including finger cooling, body cooling, room temperature and other factors such clothing and smoking. There are some versions of procedures for cold provocation and the tested fingers in the final draft. These may cause a low sensitivity of the FSBP test. To determine how the methodological difference influence the results of the FSBP test, further studies are needed. Although there are issues in the draft, the international standard of the FSBP test is extremely useful for the diagnosis, treatment and compensation of VWF.

Standardization of finger systolic blood pressure (FSBP) cooling tests

A finger systolic blood pressure (FSBP) cooling test was introduced in 1977 and standardized during the following years for the optimal provocation and best characterization of an attack of vasospastic Raynaud's phenomenon (RP). The purpose of the present review is to compare and analyse some different techniques used in FSBP cooling tests from different countries and described in the final draft of the international standard, ISO/DIS 14835-2 (2004). The selected FSBP test results indicate to some extent that the tests are reliable and have acceptable diagnostic values despite the use of different techniques to obtain them. However, only a few studies used a zero-pressure FSBP%(0) to verify an ongoing attack of vasospastic RP. Most studies used an abnormal cold reaction FSBP%(A) located below the lower limit of controls, to make the anamnestic diagnosis of RP probable. According to the ISO draft, different types of finger cooling and body thermostating can be used together in the seated or supine position, and FSBP%(A) is indicated to be used for diagnostic purposes. Further studies are recommended to solve future standardization problems not included in the upcoming ISO standard. An international agreement on the presentation and comparison of test results is needed as a supplement to ISO/DIS 14835-2.