Syncope. Good or Bad?

Updated: Dec 19, 2020

A few days back I was at a dental clinic for a minor surgical procedure. The clinic had two dental chairs, which meant that two patients can undergo treatment simultaneously.

My surgery was a simple surgical removal of an Impacted Third molar

On the second chair, a male patient with age around 30 years was seated. He was to undergo a dental extraction for a grossly carious maxillary right first molar.

A single look at the patient and I could tell that he was anxious about the procedure (of course the pic is a bit exaggerated)

I commenced my surgery. But midway through the surgery I heard the dentist from the second chair calling out the male patient’s name loudly. Curious, I stopped my procedure to have a look at what was going on.

This is what I saw. The patient was lying unconscious on the dental chair. The dentist fumbling and stressed while managing the medical complication.

So I took off my gloves and went ahead in helping the dentist manage the complication.

In India, dentistry is in a very sad state. Now a days, dental colleges churn out thousands of half-baked dental graduates throughout the country. These half-baked dentists lack even the basic knowledge of managing such medical complications.

8 years ago, I was among these half-baked dentists. That is why I want them to gain that essential knowledge through my blog.

Today I am going to talk about the most common medical emergency that occurs in a dental clinic, Vasovagal Syncope.

To manage any complication, we should understand why and how it happens. But before that we need to learn some physiology.


Our brain stays active throughout our life, even when we are asleep

Brain consumes – 20% of total oxygen and 65% of total glucose. Cerebral blood flow is 750 ml / minute.

Brain needs constant supply of oxygen & glucose. Blood is the transport medium that carries these oxygen & glucose to the brain.

If the brain is deprived of any of the two i.e., oxygen or glucose then it leads to damage to brain cells.

There's one more thing you need to know to understand why syncope occurs.

When a person is standing or in sitting position then the blood has to travel against gravity to reach the brain and majority of the blood is pooled in the lower extremities (legs) due to gravity.

Gravity pulls and keeps a lot of blood accumulated in the lower extremities.

Now when the brain is deprived of either oxygen or glucose then the brain shuts down leading to loss of motor control of the body.

If the person is standing or sitting, he will suddenly fall down laying flat or sideways on the ground.

In this position the lower extremities, heart & the brain are at equal level.

So now the blood that was pooling in the lower extremities flow back to the heart, leading to an increased venous return (more amount of blood is pushed into the heart). Also this blood doesn't have to travel against gravity to reach the brain from the heart.

Blood that was pooling in the lower extremities flow back to the heart, leading to an increased venous return. Also the blood from heart to brain doesnt have to travel against gravity so it easier for blood to reach the brain. So blood supply of brain is restored.

This leads to increased blood supply to the brain and restoration of oxygen or glucose levels in brain.

With blood supply to the brain restored, patient regains consciousness

And now the person regains consciousness.

From the above explanation it is clear that the absence of syncope will lead to permanent damage to brain cells.

Syncope is a protective mechanism of our brain

Now let us come to the most common type of syncope that occurs in a dental clinic, Vasovagal syncope.

Let me be clear, there are other types of syncope that occur due to pre-existing medical conditions. I am not going to talk about them as it is beyond the scope of this article.

I am assuming the imaginary patient that we will be dealing with in this article does not have any relevant medical history.

Pathophysiology of Vasovagal Syncope

Patient seeking dental treatment are often apprehensive.

It is a wrong belief that a dental procedure especially extraction is a painful procedure. Some people are phobic to sight of blood, needle, surgical instruments or even smell of medication of dental clinic.

On exposure to these things, mental stress is built up in a patient. And under stress, our primal instincts of Fight or Flight is activated.

During fight or flight response, our body prepares itself for an energy intensive task of a physical fight or a flight (physically running away from the situation).

During the fight or flight response, adrenal glands release Cortisol, Epinephrine & Nor-epinephrine.

Cortisol increases blood glucose level for energy intensive task of fight or flight.

Epinephrine and norepinephrine cause tachycardia, increased force of contraction, increase in blood pressure, peripheral vasoconstriction.

This leads to high blood glucose levels and high perfusion pressure of blood in the muscles required for the physically intensive task of fight or flight.

Our body has baroreceptors located at carotid sinus and arch of aorta.

Our body has baroreceptors (receptors that senses the change in blood pressure) located at carotid sinus and arch of aorta.

These are in place for autoregulation of blood pressure. When the blood pressure in our body is too high or too low, these receptors help in bringing the blood pressure to a normal range.

So now in fight or flight response, blood pressure rises sharply. This sharp rise in blood pressure is sensed by the baroreceptors. The baroreceptors relay this information to cardiovascular centres in medulla oblongata.

To maintain the blood pressure in the normal range, the cardiovascular centres activate the parasympathetic nervous system via the Vagus nerve and causes the release of acetylcholine (a type of neurotransmitter).

This acetylcholine binds with M2 muscarinic receptors near the cardiac muscles. This leads to reduction in heart rate, reduced force of contraction of heart and peripheral vasodilation.

Because of peripheral vasodilation, there is pooling of excess blood in extremities like hands and legs. This causes flush (red) appearance of extremities during a syncope. (Anatomy shown here is not accurate. This is just a schematic diagram to show the blood pooling in the extremities.)

This leads to reduced venous return (less blood returns to heart from extremities).

Reduced heart rate and reduced force of contraction leads to less cardiac output (amount of blood pumped out by heart in one minute).

Now because of reduced venous return, there is already less than normal blood available in the heart. That further adds to reduction of cardiac output.

This causes reduction of blood supply to the brain.

As we have established earlier, blood is the only transport medium for oxygen and glucose to brain. So the brain is deficient in both, oxygen and glucose.

To prevent permanent damage to the brain cells, our brain shuts down leading to motor loss of the patient and loss of consciousness.

This loss of consciousness is Vasovagal Syncope.

Now that we know how vasovagal syncope happens. Let us talk about how to manage it.


Any medical emergency that happens in a dental clinic should be managed by following the P-A-B-C-D protocol. Of Course, it goes without saying, before that you need to stop the dental procedure being performed.

P - Position

A - Airway

B - Breathing

C - Circulation

D - Definitive


The main objective of the syncope is to bring the brain at a level parallel to the heart. So put the patient in supine position with feet elevated. Keep the torso of the patient parallel to the floor.

This causes the increase in venous return to heart from the lower extremities because of gravity pull.

As there is more blood entering the heart, it automatically translates to increase in cardiac output. Also it is easier for heart to pump the blood to brain as it is not against gravity.

This leads to increased blood supply to the brain and restoration of oxygen or glucose levels in brain. And now the patient regains consciousness.

Some authors advocate putting the patient in Trendelenburg position. I advice against that.

Many authors advocate putting the patient in Trendelenburg position. But in Trendelenburg position, the diaphragm will be applying pressure over the lungs due to gravity pull. That may lead to improper breathing.


Make sure that there is no foreign body blocking the airway of the patient. Also to prevent airway blockage from the tongue, perform the Head tilt & Chin lift maneuver or make the patient lie down on left lateral side.

Make the patient lie down on left lateral side

This removes the tongue away from the upper airway.


Check if the patient is breathing on his own or not. Use Look-Listen-Feel technique to confirm.

Look-Listen-Feel technique - Look for chest movement, listen at the victim's mouth for breath sounds, feel for air on your cheek

Usually the patient is breathing on his own.

In case the patient is not breathing, go for Mouth to mouth Breathing with Cardio Pulmonary Resuscitation.


Check for the carotid pulse (most reliable) of the patient.

Radial pulse is sometimes not palpable due to extremely low blood pressure.

If no carotid pulse is palpable then go for Cardio Pulmonary Resuscitation.


When the patient regains consciousness with just proper position and maintaining airway, then give the patient something to drink or eat that is rich in glucose. Best would be glucose water. In case glucose water is not available, a sweet toffee or chocolate can also be given to the patient.

Aromatic Ammonia

If the patient is breathing properly but is still unconscious then Administer Aromatic Ammonia Inhalation. Crush the ampule between the fingers and position it under the patient’s nose. Alternatively you can soak a cotton or gauze with ammonia and place it under the patient's nose.

Aromatic Ammonia acts by causing peripheral irritation of the sensory receptors in the nasal mucous membranes and oesophageal mucosa. It also elevates blood pressure.

Now a days, ready to use ammonia pads are available to use in case of an emergency.

In case bradycardia still persists, then you will have to administer IM/IV Injection Atropine 0.6 mg (preferably IV, but IM would also do).

If the heart rate does not come into normal range, then repeat the Inj. Atropine every 5 minutes until the blood pressure rises to normal range.

Also, while you manage the medical emergency ask your assistant to call for an ambulance.


Guys, i made a mistake in the article. Recently, the sequence of management of any medical emergency has been changed to P-C-A-B-D.

Just read all the steps in the order of P-C-A-B-D.

A complication always occurs when you are not looking for it. When you are looking out for a complication, it will not happen.

So lets talk about how to prevent a vasovagal syncope from happening.


Ask the patient to have a light meal before coming to the clinic for dental procedure.

Follow the anxiety reduction protocol.

Talk to the patient. Make him feel at ease. Let him know what to expect from the procedure (Injection & dental treatment).

Reassure him that you are not going to do anything unpleasant to him.

Make sure the injection technique is as painless as possible.

If possible, prescribe anxiolytic drug like Diazepam or Alprazolam to be taken a night before and at the morning of the surgery.

Also keep in mind the age and gender of the patient.

Females usually tend to express their fear openly. That leads to release of psychological stress and prevention of syncope.

Men tend to hide their stress because of their Mard (male) ego.

Because of that the psychological stress is built up in a male patient. That leads to Fight or Flight response, leading to syncope.

Hence, it is safe to say that vasovagal syncope is seen more in male patients as compared to female patients

Young patients and adult patients are more prone to vasovagal syncope as they might be experiencing the stress related to dental treatment for the first time. So they may not be able to cope up with the stress adequately.

Whereas an older patient will have sufficient experience with a dental clinic, leading to reduction in stress. Hence less chances of vasovagal syncope.

Tom Hanks. A living legend. The only actor I can claim to be a FAN of.

To prevent vasovagal syncope, you will also have to identify the signs that occur right before the patient goes into syncope. That way you can stop the progression from pre-syncope stage to syncope stage.

Below mentioned are the signs you will se in a presyncope stage

  • Dizziness, Light-headedness, or Vertigo.

  • Blurry or narrowed vision (Tunnel Vision)

  • Nausea (feeling sick) and / or vomiting (being sick)

  • Headache.

  • Sweating.

  • Heart palpitations (faster, heavier, or irregular heartbeat felt by the person)

So now you know everything there is to know about Vasovagal Syncope in a healthy individual.

So coming back to the question I started with. Is vasovagal syncope good or bad?

It is good for the patient, as it prevents permanent damage to the brain. But it reflects bad on the operating doctor as the patient is not supposed to go into a vasovagal syncope under his watch.

I plan to write the next 3-4 articles on medically compromised patients and medical emergencies in dental clinic. So if you are interested in those topics then do signup to my mailing list to read the post as soon as it is published.

Also, do let me know what topics would you want me to write about next. The topics can be from local anesthesia, Oral & Maxillofacial Surgery or Medical emergencies.

If you find my posts helpful then share it on Whatsapp, Facebook or Twitter or any other social media platform that you use.


Recent Posts

See All