Hand Arm Vibration Syndrome Flashcards
Tell me about HAVS?
Hand-arm vibration is vibration transmitted into the hands and arms when using hand-held powered work equipment.
Too much exposure to hand-arm vibration can cause hand-arm vibration syndrome (HAVS) and carpal tunnel syndrome.
HAVS can be responsible for substantial physical impairment, disability, handicap and distress. The extent of this has only been widely accepted relatively recently.
What are clinical manifestations of Hand Arm Vibration Syndrome?
HAVS affects the nerves, blood vessels, muscles and joints of the hand, wrist and arm. It can become severely disabling if ignored.
The clinical manifestations consist generally of two main aspects:
Vascular:
- “Vibration White Finger (VWF)”
- VWF is a blanching of the fingers, which can cause severe pain, especially after exposure to the cold
- VWF has similarities with Raynaud’s disease
Neurological:
- Carpal tunnel syndrome is a nerve disorder which may involve pain, tingling, numbness and weakness in parts of the hand, as well as the associated objective neurological sensory deficits
- Carpal tunnel can be caused by, among other things, exposure to vibration
There may be other manifestations related to the above, e.g. damage to bone and muscle. Dupuytren’s contracture (usually affects one of the flexor tendons of the ring finger) might also be the consequence of cumulative trauma to the palm of the hand.
What are symptoms of Hand Arm Vibration Syndrome?
- Tingling and numbness in the fingers (which can cause sleep disturbance)
- Inability to feel things with the fingers
- Loss of strength in the hands (may be less able to pick up or hold heavy objects)
- In the cold and wet, the tips of the fingers going white then red and being painful on recovery (vibration white finger)
Continuing to use high-vibration tools will worsen the symptoms, for example:
- The numbness in the hands could become permanent and result in total loss of feeling
- Difficulty picking up small objects such as screws or nails
- The vibration white finger could happen more frequently and affect more fingers
Who is at risk of Hand Arm Vibration Syndrome?
Anyone regularly using hand-held or hand-guided power tools and machines such as:
- Concrete breakers or concrete pokers
- Sanders, grinders or disc cutters
- Hammer drills
- Chipping hammers
- Chainsaws, brush cutters, hedge trimmers or powered mowers
- Scabblers or needle guns
Also at risk are workers holding workpieces which vibrate while being processed by powered machinery, such as pedestal grinders.
Occupations where hand-transmitted vibration is common include construction workers, metal-workers, welders, foresters, ship-builders, foundry workers and road workers.
What are the legal duties of an employer?
The Control of Vibration at Work Regulations (2005) require an employer to:
- Assess the vibration risk to employees
- Decide if they are likely to be exposed above the daily exposure action value (EAV) and if they are:
- Introduce a programme of controls to eliminate risk, or reduce exposure to as low a level as is reasonably practicable
- Provide health surveillance (regular health checks) to those employees who continue to be regularly exposed above the action value or otherwise continue to be at risk
Decide if they are likely to be exposed above the daily exposure limit value (ELV) and if they are:
- Take immediate action to reduce their exposure below the limit value
- Provide information and training to employees on health risks and the actions being taken to control those risks
- Consult the trade union safety representative or employee representative on proposals to control risk and to provide health surveillance
- Keep a record of risk assessment and control actions
- Keep health records for employees under health surveillance
- Review and update the risk assessment regularly
What is the exposure action value?
The exposure action value (EAV) is a daily amount of vibration exposure above which employers are required to take action to control exposure.
The greater the exposure level, the greater the risk and the more action employers will need to take to reduce the risk.
For hand-arm vibration, the EAV is a daily exposure of 2.5 m/s2 A(8).
What is the exposure-limit value?
The exposure limit value (ELV) is the maximum amount of vibration an employee may be exposed to on any single day. For hand-arm vibration, the ELV is a daily exposure of 5 m/s2 A(8). It represents a high risk above which employees should not be exposed.
What is the pathophysiology of HAVS?
- Hand-Arm vibration causes tissue shearing and bending
- This mechanical trauma leads to tissue + endothelial damage through oxidative stress and inflammation
- Vascular endothelial cell damage leads to release of potent vasoconstrictor endothelin-1
What is Hand Arm Vibration Syndrome?
An occupational disease of vascular, neurological and musculoskeletal systems of the upper limb caused by excessive exposure to hand-transmitted vibration
Who first described Hand Arm Vibration Syndrome?
- This was identified by the ‘mother of occupational medicine’ Dr Alice Hamilton when vibratory tools first began being used
- She was the first women elected to faculty at Harvard University
What is vibration white finger (VWF)?
Vibration White Finger (VWF) is episodic finger blanching (usually causing fingers to go marble white, as opposed to cyanotic). It is usually induced by the cold.
- VWF affects the areas most in contact with vibrating parts
- During the attack it causes numbness and coldness
- During the recovery, it can cause parasthesiae and hyperaemia
It can impair hand function by causing weakness of grip and/or reduced manual dexterity via a neuropathic or myopathic origin
How can HAVS be graded?
HAVS is graded via the Stockholm Workshop scales.
- One scale classifies vibration white finger (VWF)
- One scale classifies sensoineural HAVS
Tell me about the Stockholm Workshop Scale for classifying Vibration White Finger
0 - no attacks
1 - Mild. Occasional attacks affecting only the tips of one or more finger
2 - Moderate. Occasional attacks affecting distal and middle (rarely also proximal) phalanx of one or more fingers
3 - Severe. Frequent attacks affecting all phalanges of most fingers
4 - Very Severe. Frequent attacks affecting all phalanges of most fingers, with trophic skin changes in the finger tips.
Tell me about the Stockholm Workshop Scale for classifying Sensoineural HAVS?
0SN - exposed to vibration but no HAVS
1SN - intermittent numbness with or without tingling
2SN - intermittent or persistent numbness, reduced sensory perception
3SN - intermittent or persistent numbness, reduced tactile discrimination and/or manipulative dexterity
