Use of questionnaire screening for vibration white finger in a high risk industrial population

OBJECTIVES

To compare the results of questionnaire screening with those of objective testing in the identification of vibration white finger (VWF) in a high risk population.

METHODS

Three groups of men (79 riveters, 52 healthy controls and 79 compensation claimants) were assessed for VWF by a detailed questionnaire covering occupational and general medical history and incorporating specific questions related to the presence or absence of relevant symptoms in their hands. Each then underwent provocative cold testing under controlled conditions using established protocols. The presence or absence of digital vasospasm following cooling was determined by finger systolic pressure measurements using laser Doppler flowmetry. The test protocols used have been evaluated in patients with a clear clinical diagnosis of non-occupational Raynaud's syndrome.

RESULTS

6.3% of the riveters and 83.5% of the claimants reported specific Raynaud's syndrome symptoms but 30.4% of the riveters and only 19% of the claimants tested positive for vasospasm after middle phalangeal cooling to 10 degrees C for 5 min. Using a more severe cooling protocol provoked vasospasm in 46.8% of the claimants. Lack of sensitivity or specificity of the objective testing could not explain the large discrepancies between the findings in the riveters and in the claimants.

CONCLUSIONS

Questionnaire responses concerning VWF symptoms can be influenced by the context in which they are recorded. It is important to employ more objective methods in assessing all workers at risk of developing VWF.

Digital vascular responses and serum endothelin-1 concentrations in primary and secondary Raynaud's phenomenon

OBJECTIVE

To determine circulating endothelin-1 levels (ET-1) in patients with primary or secondary associated Raynaud's phenomenon (RP) under resting conditions and in response to cold provocation.

METHODS

Patients were categorised as primary RP (18) or scleroderma associated RP (14). Finger blood flow was measured by venous occlusion plethysmography at finger temperatures of 32 degrees C and 24 degrees C. Vasospasm was detected as a finger systolic pressure of 0 mm Hg after standardised provocative cooling. Severity of vasospasm was assessed by the level of cooling required to provoke spasm. Plasma ET-1 levels were measured in antecubital blood withdrawn under baseline conditions (finger 32 degrees C) and at the point of vasospasm. Measurements were also made in 19 matched control subjects.

RESULTS

Finger blood flow was lower in patients with RP than in controls, with no difference between the two RP groups. Vasospasm occurred in all patients with RP but not in any control subjects and a grading system of severity was established. Baseline plasma ET-1 levels were similar in patients with RP and controls. Increases in ET-1 levels at the point of vasospasm in patients or corresponding timepoint in controls were also similar. There was no significant difference between the ET-1 levels in the two RP subgroups when the fingers were warm or when vasospasm was present.

CONCLUSIONS

These results do not support the hypothesis that ET-1 plays a part in the pathogenesis of RP. Objective testing is a useful adjunct to the clinical diagnosis of RP and allows assignment of a severity grade.

Acute effects of vibration on peripheral blood flow in healthy subjects

OBJECTIVES

The main objective was to study the acute vascular effects in the hands of normal healthy subjects of a complex vibration spectrum similar to that generated by many industrial hand held tools. The effects of repeated bouts of vibrations and alterations in the intensity of vibration were also studied.

METHODS

Blood flow was measured by venous occlusion plethysmography with strain gauges. Vibration across a frequency range of 0.4 to > 4000 Hz was generated by a pneumatic chisel and applied to the right hand. Blood flow was measured in both middle fingers, both big toes, or both forearms before, during, and after a two minute period of vibration. Systolic pressure of a finger and heart rate were also measured.

RESULTS

Vibration was associated with a significant bilateral reduction in finger and toe blood flow (P < 0.01 and P < 0.03) and a significant increase in heart rate (P < 0.05) but had no effect on forearm blood flow. The finger response was not abolished by repeated bouts of the vibration but was initially most notable during the first minute of vibration. Increasing the intensity of vibration delayed recovery.

CONCLUSIONS

Hand vibration causes a generalised increase in sympathetic tone in the heart and extremities. This may be a factor in the development of vasospastic disease in habitual users of hand held industrial vibrating tools.

An investigation into the acute vascular effects of riveting

Measurements were made on 46 pairs of riveters and matched control subjects before and after a morning's work. Before starting work, the mean resting finger systolic pressure was 112 (SEM 3.3) mm Hg in the riveters, similar to 117 (1.7) in the control subjects. After cooling the middle phalanx to 10 degrees C for five minutes, 16 riveters but only one control subject exhibited digital vasospasm and these numbers were unaltered after a morning's work. A subgroup of riveters whose role was always to provide counter pressure to the rivet gun showed a higher incidence (45%) of cold induced vasospasm than did riveters who invariably held the gun (10%) or rotated between both roles (27%). Plasma levels of three markers of vascular activity, endothelin-1 (ET-1), von Willebrand factor antigen (vWFAg), and angiotensin converting enzyme (ACE), were measured in non-smoking riveters and control subjects. Before work, ET-1 concentrations were slightly lower (p < 0.05) in the riveters, but vWFAg concentration and ACE activity were similar in riveters and control subjects. Riveting for a morning did not alter ET-1 concentration or ACE activity but did induce a small increase (p < 0.05) in vWFAg concentration, which may indicate damage to the endothelium. This type of vascular assessment may be helpful in assessing vasospastic complications in workers exposed to vibration.

Objective testing for vasospasm in the hand-arm vibration syndrome

Since vibration white finger (VWF) became a prescribed industrial disease in 1985, objective testing for the diagnosis and grading of the severity of the condition has become desirable. Measurements have been made of finger blood flow and finger systolic pressure before and after cold challenge in 22 healthy control subjects and 34 men presenting for medical examination in connection with compensation claims for VWF. This type of testing has previously produced one false negative result in 35 patients with an established clinical diagnosis of Raynaud's syndrome and no false positives in 40 control subjects. Finger blood flow was not significantly different in the claimants and controls in either warm or cool environments at local finger temperatures from 32 degrees C down to 20 degrees C. Finger systolic pressure in the claimants was not significantly different from that in the controls when the fingers were warm at 32 degrees C. After five minutes middle phalangeal cooling to 15 or 10 degrees C, finger systolic pressure was 0 mm Hg in 22 of the claimants indicating that vasospasm had occurred. No vasospasm occurred in the remaining 12 claimants or in any of the 22 control subjects. By clinical assessment alone, 26 of the 34 claimants had been thought to have VWF and 21 (81%) of these exhibited vasospasm in the laboratory. Of the eight considered not to have VWF, only one exhibited vasospasm in the laboratory.

An objective test for the diagnosis and grading of vasospasm in patients with Raynaud's syndrome

1. Reliable objective tests for the diagnosis and grading of vasospasm would be helpful in the assessment of patients with Raynaud's syndrome. 2. Measurements of finger blood flow at local finger temperatures from 32 degrees C down to 20 degrees C did not reliably distinguish between patients with Raynaud's syndrome and matched control subjects. 3. Using laser Doppler flowmetry to detect blood cell flux in fingertip skin, there was no significant difference (Wilcoxon's signed rank test) in the finger systolic blood pressure of 28 patients with Raynaud's syndrome and their matched controls when the fingers were warm at 32 degrees C. 4. Absence of flux was considered to indicate complete vasospasm and the degree of cooling required to abolish flux indicated the severity of the vasospastic condition in an individual patient. 5. Finger cooling for 5 min did not significantly alter finger systolic blood pressure in the control subjects, but abolished blood cell flux in the fingertip skin of 27 of the 28 patients with Raynaud's syndrome. 6. A grading scale was derived from the flux measurements. There was a significant correlation (r = 0.75, P less than 0.001) between the grading of disease severity as judged by the flux test and the clinical grade as assessed before the laboratory visit. 7. There was one false-negative result in the 28 patients with Raynaud's syndrome tested and no false-positive results in 28 matched control subjects. 8. This type of testing may prove helpful in the diagnosis and grading of vasospastic disorders.

Blood flow in diabetics with foot lesions due to 'small vessel disease'

Blood flow was measured in the feet and toes of 23 diabetics, 7 controls and 6 non-diabetic neuropathic controls, using venous occlusion plethysmography. All of the diabetics showed a characteristic flow abnormality with mild hyperperfusion of the foot at rest but impaired peak flow following arterial occlusion. When the diabetics were subdivided into those with 'small vessel disease', those with neuropathic ulceration and those with neuropathy but no ulceration, the groups had remarkably comparable blood flows, except that peak great toe blood flow was rather lower in small vessel disease. In small vessel disease, the combination of high resting blood flow and elevated foot venous oxygen saturation suggests that the hyperperfusion is due to arteriovenous shunting. It seems likely that the toe lesions ascribed to small vessel disease were in fact manifestations of severe diabetic neuropathy. The term small vessel disease should be avoided in the context of diabetic foot lesions.

A plethysmograph for the measurement of digital blood flow

Venous occlusion plethysmography using a water-filled plethysmograph is an accurate and reliable method for the measurement of limb flow which has been used for many years. The technique has been adapted to produce a plethysmograph for the measurement of digital blood flow. The device is small, light, cheap, simple to use, and can be calibrated directly with the digit 'in situ'. It is especially suitable for the assessment of digital blood flow, since flow through a large portion of the whole digit is measured and the local temperature of the digit is accurately controlled.