You don't think much about anaesthesia until you're told you need surgery – and that’s when you may be stumped by the options. Other than general anaesthesia (GA), you may be offered regional anaesthesia (RA), which may involve spinal anaesthesia or peripheral nerve block – depending on the kind of surgery you're undergoing.It can be numbingly confusing to the layperson. How are the various types of RA different? Will you be wide awake? Why consider them when you’d rather get GA and be completely unconscious during surgery (“I don’t want to know what the surgeon is doing!”). That’s because you may not need GA in the first place. “More complex procedures, such as major abdominal or chest surgeries, often require GA”, said Dr Wong Wan Yi, a senior consultant with Tan Tock Seng Hospital’s (TTSH) Anaesthesiology, Intensive Care and Pain Medicine.But when it comes to procedures involving a particular area of the body, such as an arm, leg or the lower half of the body, RA may be more suitable, advised senior consultant Dr Fong Wee Kim, who heads TTSH’s Anaesthesiology, Intensive Care and Pain Medicine. “RA can also be a good option for patients who may face higher risks with GA because of existing medical conditions,” he said.These medical issues can include the patient’s “health problems, reaction to medications, past surgical experience, and risks with different types of anaesthesia”, explained Dr Joanne Yeo, a consultant with Changi General Hospital’s Department of Anaesthesia and Surgical Intensive Care.If you’re still groggy about GA and RA, read what anaesthetists have to say before making your decision. WHAT HAPPENS DURING GENERAL ANAESTHESIA (GA)?The anaesthetist is likely to first administer propofol, the most-commonly used intravenous anaesthetic agent, said Dr Yeo. Anaesthetics work by temporarily changing the brain’s electrical activity pattern. “They temporarily reduce communication between different parts of the brain producing unconsciousness, reducing awareness, and reducing perception of pain.”Strong painkillers such as opioids (for example, fentanyl or morphine) are also administered intravenously, said Dr Wong.What follows is likely an inhalational anaesthetic given through a mask, said Dr Yeo, which is used to maintain the GA. Although sometimes, “propofol can be used alone as a continuous infusion”.