JOAN CHEW finds out what you need to run through with your doctor before you are sedated for an operation
1 Type of anaesthesia
This depends on the procedure you are about to undergo, your health status and preference. General anaesthesia: Drugs are used to induce this state of unconsciousness. They also stop the brain from recognising the signals coming from the nerves, so one does not feel pain, cannot be jolted awake even by painful stimuli and has no recollection of the surgery. They are given continuously, either intravenously or inhaled through a mask. The most common drug used here to induce general anaesthesia is propofol.
General anaesthesia is usually required for long operations or those that may be very painful, such as a heart bypass, abdominal surgery and mega-liposuction. Local anaesthesia: The drug is injected into the skin or applied as a cream to block sensation to a small part of the body, such as a finger. The area goes numb and the patient does not feel any pain there. The drug does not affect awareness and sense perception in other areas, but drugs such as propofol may also be used to sedate the patient and let him sleep comfortably during the procedure. Local anaesthesia is induced during tooth extraction or surgery to remove superficial lumps in the body. Regional anaesthesia: A group of nerves is blocked to cause a larger region of the body to lose sensation, such as an arm or the entire lower half of the body. The drug can be injected into the fluid surrounding the spinal cord or a cluster of nerves. Regional anaesthesia is often induced along with sedation so patients feel calmer and less anxious during surgery on the legs or the lower abdominal area.
2 Side effects and complications
Anaesthesia is generally very safe with the right expertise, equipment and monitoring. But be prepared to deal with side effects of the drugs, such as nausea, vomiting, shivering and giddiness, though these should not last long. If a tube has been inserted down your throat to help you breathe during the operation, your throat may also be sore. More serious complications can occur if the intake of oxygen or blood circulation in the body is compromised for even a few minutes during surgery. This can lead to brain damage and death. Some patients, especially the elderly, may experience short-term memory loss after surgery, such as difficulty recalling where the car keys are. It is not known if this is caused by anaesthesia, surgery or both.
3 Risk of waking up during surgery
The risk varies according to the type of surgery and patient characteristics and is much rarer now with better monitoring equipment. Figures from the United States show the risk can be as high as one in 1,000 for high-risk patients and as low as one in 14,600 for low-risk patients. High-risk patients include trauma patients and those coming in for heart surgery as their blood pressure is likely to be very low. Doctors are cautious about giving them too much anaesthetic because it can cause their blood pressure to drop further and lead to a heart attack.
4 Medical status
How the body will cope with the stressful physiological events of anaesthesia and surgery depends mainly on the patient’s state of health and medical history. If a patient has a major systemic disease which is poorly controlled, such as diabetes and hypertension, the body would have less reserves to cope with the stress. Such patients risk greater fluctuations in vital parameters such as heart rate and breathing, which could put them at risk of organ damage and even death. Doctors may postpone surgery until their existing conditions are better managed, to reduce such risks. Someone with a history of heart problems will also need closer monitoring of his blood pressure during surgery. Anaesthetic drugs which cause a drastic drop in blood pressure are usually not used for such patients.
5 Recent coughs and colds
Nursing such ailments two weeks before a surgery may mean that your airways are still very reactive and can accumulate secretions easily. Surgery after a viral infection could further weaken heart muscles and result in myocarditis, a high risk factor for heart failure. Surgery is likely to be postponed.
6 Use of drugs, complementary medicine
It is important to inform the doctor of any traditional medicine, herbs, supplements and family remedies that you are currently taking, whether for general health or the treatment of ailments, as they may interact with drugs given during surgery and result in excessive bleeding. It is crucial for you to state upfront what drugs you are allergic to, so doctors can avoid administering them.
7 Past anaesthesia experience and that of family members
Do alert the doctor if you or any of your family members has had a poor experience with anaesthesia. If someone in the family had an unexplained anaesthesia-related death, it may point to a hereditary condition known as malignant hyperthermia. When drugs used to induce general anaesthesia are administered, the condition causes a rapid rise in body temperature and severe muscle contractions, complications which are potentially fatal, so doctors always avoid inducing general anaesthesia in such patients.
8 Lifestyle habits
Smoking and drinking alcohol give rise to challenges during surgery. The reactive airway of a smoker can be easily obstructed with secretions during surgery and cause breathing difficulties, especially when respiratory reflexes slow down during general anaesthesia. Drugs are metabolised by the liver, so a liver impaired by alcohol abuse may alter the efficacy of anaesthetic drugs and lead to an overdose.
9 Pre-surgery preparation
Ask your doctor for instructions on eating and drinking prior to surgery. Most patients are required to fast to reduce the risk of vomiting during surgery and of liquid getting into the lungs, which can cause serious problems. Women are also required to remove make-up and nail polish as this can hide changes in skin colour during surgery.
10 Post-surgery recovery
Ask where you will be sent to after surgery – is it the intensive care unit or a high dependency ward? You may also want to know if you will be kept intubated and the types of pain relief medication you will be given.
Sources: Associate Professor Ong Biauw Chi, head and senior consultant at the department of anaesthesiology at Singapore General Hospital; Associate Professor Ti Lian Kah, senior consultant at the department of anaesthesia at National University Hospital; Dr Ho Kok Yuen, clinical director of the pain management service at Raffles Hospital