Syncope Due To Low Blood Pressure - Simple Fainting
Some people are prone to blackouts due to a sudden drop in blood pressure. Doctors call this Vasovagal or Neurocardiogenic Syncope.
The reason that some people experience these episodes and others never do is not completely understood. However one in four of us will faint at some time in our life and it is most likely to be due to this condition. Some people will have only one episode in their life others may experience more frequent episodes.
You may have seen people fainting in some common situations:
- In church
- Standing during school assembly, choir or concerts
- Standing on the train, bus or tram
- Soldiers on parade ground
- In the queue at the post office or bank, supermarket or shopping centre
- At the dentist
- At the hairdresser
- After a blood test or donating blood
- After exercise
- After showering first thing in the morning
- Getting out of bed to go to the toilet
- Standing at sporting events or concerts
Most simple faints occur from a standing position but they can occur when a person is sitting. It is uncommon for a person to have a simple faint lying down, unless they lay down because they felt they were going to faint.
Many of the situations above have common features:
- the person has been standing or sitting still for a while
- the room or weather is hot or crowded
- there may be pain or anxiety involved
- the blood vessels are dilated due to a warm shower or after exercise
- there may be dehydration
- first thing in the morning
- fasting for a blood test
- inadequate fluid intake when out on a hot day
Fainting is even more likely when these situations are combined, for example
- getting out of bed to go to the bathroom, when you have the ‘flu’, having been in bed all day and having not eaten or drunk anything
- standing in a crowded train carriage train going to work having missed breakfast and having had a few glasses of wine the night before.
- working in the garden on a hot day when you haven’t drunk enough water then coming inside and having a warm shower
Common warning feelings before a faint
Usually a person will feel unwell for short time before they faint.
Older people may faint without any warning.
Before fainting a person may feel
- lightheaded
- very hot
- their vision may blacken or blur
- nauseated, have abdominal pain or want to open their bowels
- they want to get out of the room
- they are ‘fading’ or need to sit down
- weak or feel their legs giving way
These symptoms indicate that the blood pressure has started to fall and the brain is not receiving enough blood supply.
How does someone look before they faint:
A person about to faint may look
- very pale
- sweaty
If their blood pressure is falling they may appear vague, or may not make sense when they are talking.
If the person lies down at this point they may not go onto faint.
Fainting
If a person faints, they will collapse to the ground or slump in their
chair.
They will appear pale and usually sweaty.
They may have muscular jerking for a short time (usually less than a minute), which can be mistaken for a seizure.
They may lose control of their bladder or bowels.
First Aid
See Information for Patients – First Aid.
After a Simple Faint
After a simple faint, a person will usually regain consciousness quickly (within a minute or so). The time to recovery can be longer in the elderly or if the person is kept upright when they faint.
Often after a simple faint the person will feel nauseated and washed out but will know who and where they are. It is very common to feel very tired for a few hours and feel the need to sleep.
It is best to leave a person who has fainted lying down for at least 15 minutes or until their colour returns to normal. Getting up too quickly can result in a further faint.
Diagnosis
A simple faint can often be diagnosed from the history of when and where it occurred and how the person felt before and after they fainted.
If an ECG and cardiac examination are normal and there are no issues of concern in your past history or family history no further investigation is required.
If the episodes are occurring more frequently or some of the classical features are not present further investigations may be arranged.
These include:
Echocardiogram to help exclude other causes of blackouts
Tilt
table test to try to bring on one of your usual blackouts
Treatment
Simple faints can usually be treated by teaching the person about:
- the situations in which they are likely to occur
- the warning signs that come on before the blackout so they can sit or lie down
- avoiding dehydration
- increasing salt intake when appropriate
- leg manoeuvres to perform with prolonged standing to help return blood from the legs to the heart
Sometimes medications are required if episodes are continuing despite simple measures.
