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? That's because you may not need GA in the first place.

What Happens During General Anaesthesia (GA)?

General anaesthesia is a medically induced, reversible state of unconsciousness achieved using a combination of drugs, including painkillers . Drugs are injected into your vein or breathed in as gases into the lungs .

The anaesthetist is likely to first administer propofol, the most commonly used intravenous anaesthetic agent. Anaesthetics work by temporarily changing the brain's electrical activity pattern . Strong painkillers such as opioids are also given intravenously .

What follows is likely an inhalational anaesthetic given through a mask, used to maintain the GA . When you are fully unconscious, a breathing tube is inserted through your mouth, past the vocal cords and into the windpipe. It keeps the airway open, delivers oxygen, and protects the lungs from stomach fluids .

What Anaesthetists Do During Surgery

To ensure that you don't wake up or feel pain during surgery, anaesthetists calibrate the medicines' levels carefully . It is also the anaesthetist's job to monitor your blood pressure, heart rate and oxygen levels during surgery, as the drugs can affect your brain and heart . "Because of the effect of the medications on the heart, and the patient entering a very deep 'sleep' state, the blood pressure tends to show more fluctuations," explains an anaesthetist from Singapore General Hospital.

At the end of surgery, the GA medicines will be ceased. The anaesthetist will monitor when it is safe to remove the breathing tube as the patient wakes up – in addition to ensuring pain control and normal vital signs .

Common Side Effects After GA

Nausea, vomiting and giddiness can be linked to the residual effects from the anaesthetic agents . They can resolve within an hour or a day for some patients. If you are normally prone to these effects, it is important to let your anaesthetist know in advance.

Other common temporary side effects include:

• Sore throat due to the breathing tube

• Shivering

• Headache

• Drowsiness

• Aches and pains due to body posture during surgery

Serious complications such as heart attack, stroke or allergic reactions to drugs are very rare . Death or permanent disability related to anaesthesia is extremely rare .

How Does Regional Anaesthesia (RA) Work?

RA numbs the specific part of the body undergoing surgery . The main medications used are local anaesthetics, which temporarily block pain signals from travelling to the brain . Painkillers such as opioids are still administered intravenously, though to a lesser extent.

RA often provides better pain relief after surgery – along with a lowered risk of side effects such as nausea and vomiting . There's also no need for a breathing tube .

Types of Regional Anaesthesia

Spinal Anaesthesia (Spinal Block): A single shot of anaesthetic is injected at the lower back into the spinal fluid surrounding the nerves . It works within a few minutes to completely numb the lower half of the body. This numbing ability gradually wears off after four to six hours . Patients usually are awake the moment the operation finishes and feel more refreshed .

Epidural Anaesthesia: Local anaesthetic and other pain medicines are given using an epidural catheter (a small tube) inserted into the back, just outside the spinal fluid . A small catheter allows the anaesthetic to be topped up. Epidural analgesia is commonly used to help reduce labour pain .

Peripheral Nerve Blocks: Ultrasound is used to locate the nerves that supply the area being operated on, such as the arm, shoulder, leg or foot. Then, the anaesthetic is injected around the nerves . Nerve blocks typically last 8 to 16 hours .

Will You Be Awake If You Opt for RA?

It depends on your needs and comfort level . You may choose to remain awake, or opt for sedation to help you relax or sleep during the operation. "Most of our patients managed to sleep throughout the surgery; some even commented their 'sleep' as one of the best they have ever had," notes a Singapore-based anaesthetist.

Procedural sedation involves administering sedative and sometimes analgesic drugs during a procedure which can be uncomfortable or painful . You may feel drowsy for a few hours following sedation .

What Surgeries Is RA Usually Used For?

RA is most commonly used for:

• Orthopaedic surgeries such as hip and knee replacements, fracture repairs, shoulder surgery and hand surgery

• Vascular procedures involving the legs

• Lower abdominal procedures such as hernia repairs

• Day surgeries

In spine surgeries performed at Singapore General Hospital, spinal anaesthesia is gradually replacing GA. Since 2024, more than 200 spine surgeries have been performed with patients opting to stay awake using endoscopic decompression – a minimally invasive surgery that relieves pressure on compressed spinal nerves .

Final Thoughts

The choice between general and regional anaesthesia depends on the type of surgery, your medical conditions, and your preferences. Your anaesthetist will discuss the options with you before surgery . The practice of anaesthesia is very safe, and the goal is always to ensure your comfort and safety throughout the procedure .