Smoking increases the risk to your heart during surgery

Your heart works very hard, pumping about 70 times per minute to circulate blood around your body. It needs large amounts of oxygen to be able to do this.

Nicotine in cigarette smoke makes your heart beat faster and more forcefully. This increases the amount of oxygen it needs.

Cigarette smoke also contains carbon monoxide, which combines with hemoglobin in your blood to form carboxyhemoglobin. This prevents hemoglobin from carrying oxygen to the heart and the rest of your body.

This combination of a heart which needs more oxygen with blood which cannot supply it so well, is very serious, and can lead to a heart attack, where part of the heart muscle dies for lack of oxygen.

Is this just a theory, or is it something anesthesiologists can see happening?

Dr Woehlck and others showed that it is a real affect, in a study called “Acute Smoking Increases ST Depression in Humans During General Anesthesia”. (available online at He explained this publication to the public in an article entitled Smoking Before Surgery- a Dangerous Decision).

He looked at ST depression, an abnormality of the ECG tracing that anesthesiologists see when the heart is not getting enough oxygen for the work it is doing. He also measured carbon monoxide level in patients breath. The only way that patients get significant amounts of carbon monoxide in their breath is by smoking. The more they smoke, the higher the carbon monoxide level will be. What did he find?


Increase in Risk to Heart (as ST Depression) with Amount Smoked (as CO level).

Clearly, the more you smoke, the higher the risk that your heart will not get enough oxygen during surgery. Overall, smokers had nine times the cardiac risk of non-smokers.

The good news from this research is that half life of carboxyhemoglobin is four hours. This means that the level of carboxyhemoglobin drops by half every four hours. After 8 hours of non-smoking, the risk is only 1/4 of what it was to start with, and after 12 hours it is 1/8th. This is why even stopping smoking the night before surgery, and remaining smoke free till after the surgery, will significantly decrease the risk to your heart.

This is a good reason why you should “Stop Smoking for Safer Surgery”.