Introduction
In some crash reports, we are informed that the driver lost control of his vehicle after suffering “a medical episode”. This most often includes having suffered a heart attack, stroke, fainting etc.
In this section, we would like to investigate how blood pressure impacts on driver fitness and why maintaining a healthy blood pressure is important for safe driving.
Normal levels of blood pressure are particularly important for the efficient function of vital organs such as the heart, brain and kidneys and for overall health and wellbeing.
Not only is blood pressure an important consideration for drivers, but also the recommended medication and possible side effects thereof.
Blood Pressure Medication and Driver Fitness
It is generally accepted that while high blood pressure can lead to heart attacks and strokes, low blood pressure can cause dizziness, blurred vision and confusion. All of these are dangerous conditions when the focus is needed in dangerous activities such as driving a motor vehicle.
There is medication available to treat both high and low blood pressure. Drivers who are aware of their abnormal blood pressure and who are using prescription medication should always be alert to the side effects of medication.
According to the New Mexico Department of Health, certain drugs can interfere with factors that are essential for safe driving, such as:
Coordination - needed for steering, braking, accelerating, and manipulating the vehicle;
Reaction time - needed to respond in time and appropriately deal with certain situations;
Judgment - helps with risk assessment, avoidance of hazards, and emergency decision-making;
Tracking - helps to stay in the lane and maintain the correct distance from other cars and obstacles;
Attention - ability to handle the high demand for information-processing;
Perception - needed for glare resistance, dark and light adaptation, and dynamic visual acuity.
The reactions caused by certain types of medication may include nausea, drowsiness, blurred vision, inability to think clearly, reduced coordination and diminished motor or judgment skills and can, therefore, impair your ability to drive. These medications include over-the-counter medication as well as scheduled medication, prescribed by the doctor.
What is Blood Pressure and what would be a Healthy Blood Pressure?
Blood pressure is the pressure of the blood in your arteries. Blood is carried from the heart to all parts of the body in blood vessels. Each time the heart beats, it pumps blood into the vessels/arteries. The pressure of blood flowing through the arteries varies at different times in the heartbeat cycle.
You need a certain amount of pressure to keep the blood flowing. Your heart is a pump that beats by contracting and then relaxing.
- The highest pressure, known as systolic pressure, is the pressure when the beat or contraction of your heart forces blood around your body.
- The lowest pressure, called diastolic pressure, is the pressure between heartbeats when the heart is resting.
Blood pressure is measured in millimetres of mercury (shortened to ‘mmHg’). A blood-pressure reading gives two numbers. The first number is the systolic pressure and the second is the diastolic pressure.
Your target is to have a blood pressure below 140/85mmHg (140 systolic and 85 diastolic). If you have diabetes, kidney disease, or disease of the heart and circulation, your target is below 130/80mmHg.5
There is no fixed dividing line between normal blood pressure and slightly raised blood pressure. However, the British Hypertension Society suggests that the ideal blood pressure is 120/80mmHg, and normal is less than 130/80mmHg.
What do we know about High Blood Pressure/ Hypertension?
Hypertension, also known as high or raised blood pressure, is a condition in which the blood vessels have persistently raised pressure. The higher the pressure in blood vessels the harder the heart has to work in order to pump blood. People with high blood pressure run a higher risk of having a stroke or a heart attack
If left uncontrolled, hypertension can lead to a heart attack, an enlargement of the heart and eventually heart failure. Blood vessels may develop bulges (aneurysms) and weak spots due to high pressure, making them more likely to clog and burst. The pressure in the blood vessels can also cause blood to leak out into the brain causing a stroke. Hypertension can also lead to kidney failure, blindness, rupture of blood vessels and cognitive impairment.
Hypertension is defined as a systolic blood pressure equal to or above 140 mm Hg and/or diastolic blood pressure equal to or above 90 mm Hg.
Many people who have high blood pressure don’t have any symptoms at all, so it very often goes undiagnosed.
Risk factors for the development of hypertension/ high blood pressure:
- Consumption of food containing too much salt and fat, and not eating enough fruit and vegetables
- Harmful levels of alcohol use
- Being overweight
- Physical inactivity and lack of exercise
- Poor stress management.
- Genes are another factor. So, if one or both of your parents have (or had) hypertension, you have a greater chance of developing it too.
All adults should know their blood pressure level and should also find out if a close relative had or has hypertension as this could place them at increased risk.
How can we prevent or minimize odds of developing high blood pressure and its adverse consequences?
- Healthy diet
- Avoid harmful use of alcohol
- Regular physical activity
- Maintaining a normal body weight
- Stopping tobacco use and exposure to tobacco products
- Proper management of stress
- Monitoring blood pressure at home if feasible
- Checking blood sugar, blood cholesterol and urine albumin
- Knowing how to assess cardiovascular risk using a risk assessment tool
- Following medical advice
- Regularly taking any prescribed medications for lowering blood pressure.
What do we know about Low Blood Pressure/ Hypotension?
Low blood pressure - also known as hypotension - is when your blood pressure is below 90/60mmHg. This does not necessarily mean that there is a problem. In fact, people with low blood pressure generally tend to live longer than those with high blood pressure and even those with normal blood pressure.
Most people with low blood pressure don’t have any noticeable symptoms.
Symptoms may however include:
- Low blood pressure can cause dizziness, blurred vision and confusion.
- The onset of dizziness can occur quickly, especially when standing suddenly. The resulting dizziness could result in a fall that could injure you. Also, fainting is a danger of low blood pressure. Fainting can result in serious bodily harm, resulting from a fall when going unconscious.
- Shock occurs when there is not enough blood reaching major organs, including the brain. The early signs of shock are lightheadedness, confusion and sleepiness. As the condition progresses, it will be difficult to sit up and not pass out. Shock can be fatal and should be treated immediately.
Low blood pressure could be an indicator of a more serious problem. Causes may include
- Blood loss
- Severe infection/sepsis
- Severe dehydration from vomiting, diarrhoea or fever
- Heat exhaustion or heat stroke
- Heart problems such as heart attack or heart disease
- Heart failure and faulty heart valves
- Severe allergic reaction
- Endocrine problems such as overactive or underactive thyroid
- Addison's disease
- Low blood sugar
- Diabetes
- Liver disease
- A severe allergic reaction, called anaphylaxis
Low blood pressure is sometimes associated with certain symptoms, many of which are related to causes rather than effects of hypotension:
- Chest pain
- Shortness of breath
- Irregular heartbeat
- Fever higher than 38.3°C (101°F)
- A headache
- Stiff neck
- Severe upper back pain
- A cough with phlegm
- Prolonged diarrhoea or vomiting
- Dyspepsia (indigestion)
- Dysuria (painful urination)
- An adverse effect of medications
- Acute, life-threatening allergic reaction
- Seizures
- Loss of consciousness
- Profound fatigue
- Temporary blurring or loss of vision
- Connective tissue disorder Ehlers-Danlos Syndrome
- Black tarry stools
How to manage low blood pressure
In most people, there is usually no need to treat low blood pressure. Only a very small number of people need to take medication for it. Steps to managing low blood pressure would include:
- Making sure you are drinking enough fluids. This is especially important if you become sick or have diarrhoea, as these can both lead to an increased fluid loss in the body.
- If you get postural hypotension, there are certain things you can do to avoid the problem - such as getting out of bed slowly in the morning and using handrails to support yourself when you get out of the bath.
Treatment: #NB Always contact a medical doctor for effective diagnosis and treatment
Blood Pressure and your Ability to Drive
High blood pressure has few symptoms and it should not affect your ability to drive. However, you should not drive if your medicines cause symptoms which affect your driving ability. If this happens, ask your doctor if he or she can change your medicines to prevent the symptoms.
Women need to have their blood pressure checked regularly throughout pregnancy, whether they have high blood pressure or not. Blood pressure usually falls in the first few months of pregnancy, even in women who have been diagnosed with high blood pressure.
High blood pressure can develop for the first time in pregnancy - a condition called ‘pregnancy-induced hypertension’. This may lead to a more serious condition called pre-eclampsia, which needs treatment with bed rest and drugs.
Blood pressure usually returns to normal after the pregnancy and the problem may not happen again in future pregnancies.
Professional Drivers, Blood Pressure and Disclosure
If you have high blood pressure then you should be able to drive a car or a motorcycle for personal use with no problem. There are however important considerations for professional drivers in many countries across the globe.
The medical standards for driving buses and large trucks and buses are much higher than for those driving a car or motorcycle. This is because the vehicles are much larger and heavier and because you may spend much more time behind the wheel, especially if driving is part of your job.
Commercial motor vehicle drivers have a greater propensity to develop hypertension than their peers in other professions. As the years of experience rise, part of the increase in hypertension may relate to accompanying ageing, increase in body mass, or decline in physical activity.
If you have a licence to drive a large goods vehicle or passenger-carrying vehicle you will need to inform the traffic authorities if your blood pressure and medicines cause side-effects (problems) that could interfere with your ability to drive.
You may need to stop driving, find a different medicine and apply to renew your licence once your high blood pressure is under control. For example, beta-blocker medicines may cause you to feel dizzy or tired and if this happens to you, you may not be able to drive and, with your doctor's help, you will need to find another medicine.
If your resting blood pressure is consistently 180mmHg systolic (top or maximum number) or more and/or 100mmHg diastolic (bottom or minimum number) or more then you should not drive a bus or large lorry. The good news is that once your blood pressure has been lowered and is under control, you can then be re-licensed.
[This medical standard usually also applies to drive a taxi, manning a boat or ship with passengers or flying an aircraft with passenger]
Road Legislation in South Africa
The Road Legislation in South Africa is rather vague with regards to blood pressure and the ability to drive.
Section 15 of the National Road Traffic Act deals with the disqualification to drive resulting from medical conditions and disabilities, while Section 16 covers the procedure to follow:
Herewith an Excerpt from the Act:
Sec 15. Disqualification from obtaining or holding learner’s or driving licence
(1) A person shall be disqualified from obtaining or holding a learner’s or driving licence—
(f) if he or she is suffering from one of the following diseases or disabilities:
(i) Uncontrolled epilepsy;
(ii) sudden attacks of disabling giddiness or fainting due to hypertension or any other cause;
(2) The chief executive officer concerned may, if he or she deems it expedient and on such conditions as he or she may deem fit, declare that any person shall no longer be subject to any disqualification, suspension or cancellation by a competent authority referred to in subsection (1) (b), (c) or (d), respectively: Provided that in the case of any cancellation such declaration shall be subject to section 25 (9).
Sec 16. Failure to disclose disqualification in respect of licence authorising driving of motor vehicle prohibited
(1) No person shall, when applying for a learner’s or driving licence, willfully fail to disclose any disqualification to which he or she is subject in terms of section 15.
(2) Any person who—
(a) is the holder of a licence authorising the driving of a motor vehicle in terms of this Chapter; and
(b) becomes aware thereof that he or she is disqualified from holding such licence,
shall, within a period of 21 days after having so become aware of the disqualification, submit the licence or, in the case where it is contained in an identity document, that document to the chief executive officer of the province concerned.
(3) When a licence is submitted in terms of subsection (2) the chief executive officer shall cancel it and if the licence was issued in a prescribed territory he or she shall notify the authority which issued it of the cancellation: Provided that if the chief executive officer is satisfied that the holder thereof is competent to drive the class of motor vehicle concerned with the aid of glasses, an artificial limb or any other physical aid, the chief executive officer shall, in the case where the licence—
(a) is contained in an identity document—
(i) not cancel the licence, but endorse the licence accordingly and such endorsement shall be a condition subject to which the licence is held;
(ii) return the identity document to the holder thereof; or
(b) is not contained in an identity document, issue or authorise the issue of a new licence in the prescribed manner reflecting the conditions on which it is issued.
Blood pressure and Car Insurance
Not only does the licensed driver have to disclose any hypertension or blackouts to the licensing authorities - the driver should also need to consider the vehicle insurance contract. A history of hypertension or blackouts will be deemed a material fact. If after an accident it appears that there has been a prior history of blackouts or hypertension that has not been disclosed such failure to disclose may be regarded as a breach of contract.
Conclusion
Driver error is blamed for approximately 85% of fatal road crashes in South Africa. The healthier the driver the better he/she will be equipped to remain focused, alert and able to reduce these driver errors or the threat of suffering “a medical episode”.
Also view:
Medication and Road Safety
Physical Fitness and Road Safety
Road Safety and Health
Pregnancy and Road Safety