Anaesthesia

Anaesthesia is a drug given before a surgical procedure in order to prevent pain and numb the surgical site. There are various methods of administering anaesthesia depending on the purpose. These include inhalation, topical, injection, skin patch, drops and others.

Anesthesiologists are specialists who administer anaesthesia and manage the patient during the surgery. However, other medical professionals who are licensed to administer anaesthesia are dentists, nurses, other surgeons and general physicians.

On administering anaesthesia, the patient loses pain sensation in the affected areas. However, the motor senses are still intact. This means that patients feel no pain but will know what is going on. For instance, when anaesthesia is given to remove a tooth, patients do not feel pain but understand that the tooth is being pulled.

The drugs employed to provide anaesthesia are termed anaesthetics. They primarily block the nerve signals from the nerve to the brain responsible for giving the sensation of pain. Once the effect of the anaesthesia wears off, normal sensations are restored.

Types

Depending on the type of surgery, anaesthesia may be injected locally, regionally, given sedation, or the whole body is anaesthetised. The different types of anaesthesia can be explained as follows:

• Local anaesthesia: Local anaesthesia is administered when only a small section of the body needs numbing—for example, cataract surgery, a dental procedure or a skin biopsy. The patient is kept awake during the procedure. The effect of anaesthesia wears off within 3-4 hours of injection.
• Regional anaesthesia: Regional anaesthesia numbs a larger part of the body. This includes the limb or the entire body below the chest. Patients sometimes have a choice of staying awake during the procedure or sleeping through sedation in addition to the regional anaesthetic. For instance, an epidural is given to alleviate pain during childbirth or during a cesarean section (C-section), spinal anaesthesia is given for hip or knee surgery or numbing the arm for surgeries on the hand.
• General anaesthesia: General anaesthesia provides absolute unconsciousness and makes the patient insensitive to pain or any other stimuli. It is administered to perform highly invasive procedures such as on the brain, heart or abdomen.
• Sedation: Sedation helps patients relax and puts them to sleep. However, they can be easily aroused or awakened once the procedure is completed. Light sedation is often prescribed by the anaesthetist, surgeon performing the surgery, and nurse. However, deep sedation requires training. Some examples are cardiac catheterisation and colonoscopies. An anaesthesia professional provides deep sedation because your breathing may be affected by stronger anaesthetic medications.

Symptoms

Anaesthetised areas often show typical symptoms that confirm that the effect of anaesthesia has taken place. Some signs and symptoms include:

• Feeling heavy in the affected area
• Feeling swollen
• Loss of pain sensation
• Difficulty swallowing in case of anaesthesia in the oral cavity or mouth

When to see an Anaesthesiologist, and how do they help?

Anaesthetists are doctors who specialise in providing anaesthesia to patients for various surgical operations. Moreover, they deal with intensive care and management of pain. For a particular operation and during the operation, they perform the following duties:

• Discuss a complete medical history, family history and personal history.
• They discuss the kind of anaesthesia that a specific case requires.
• They discuss the risks and complications associated with the administration of anaesthesia.
• They take consent with regards to the chosen anaesthetic, the type of pain control agreed to and permission to perform the procedure.
• Manage blood transfusions if required.
• They help plan any critical care cases in the Intensive Care Unit or High Dependency Unit.
• They help put the patient at ease and ensure optimal care during the procedure.
• Apart from managing pain during childbirth, intensive care, high dependency, pain clinics and resuscitation services, they assist with hospital administration, research and auditing, teaching and training.

During the surgical procedure

• They administer a single or combination of anaesthetics, including anti-nausea medications.
• They also monitor vital signs such as blood pressure, pulse, blood oxygen level, and heart rate.
• They identify and manage any problems that may occur, including an allergic reaction or changes in the patient's vital signs.
• Lastly, they also provide postsurgical pain management for patients who have undergone extensive surgery.

Apart from the above, anaesthesiologists also prepare to deal with any emergency caused by anaesthesia during and after the surgery. Some of these include:

• Anaesthetic awareness: For unknown reasons, many patients experience awareness during a surgical procedure despite general anaesthesia. In such cases, anaesthesiologists inject more potent doses if patients complain of discomfort.
• Collapsed lung or atelectasis: Surgery that uses general anaesthesia or a breathing tube sometimes leads to a collapsed lung. This issue is rare and occurs when air sacs in the lung deflate or fill with fluid. Anaesthesiologists are trained to handle such an emergency situation.
• Malignant hyperthermia: Some people with malignant hyperthermia may experience a detrimental reaction to anaesthesia. This syndrome is rare and causes fever and muscle contractions during the surgical procedure. Hence, it is advised to mention this in the history so that the anaesthesiologist prepares themselves to combat it in case things go wrong during the procedure.
• Nerve damage: This is a rare occurrence. Most people experience this when the nerve is pricked during injection of anaesthesia, which may lead to permanent or temporary damage such as numbness, neuropathic pain, or weakness. However, this condition is uncommon and always discussed during consultation.
• Postoperative delirium: Older people are more susceptible to experiencing this condition that lasts about a week episodically. Some people may also experience long-term memory and learning issues. This condition is termed postoperative cognitive dysfunction. Like others, people are informed about it at the time of consultation.

Recovering from Anaesthesia

The effect of local anaesthesia wears off within 3-4 hours of injection. However, regional or general anaesthesia can take longer. The anaesthetics remain in the body for over 24 hours. One should avoid driving or working until the effects have subsided completely.

Normal activities can be resumed after local anaesthesia or advised by the doctor. Once the patient recovers from anaesthesia, the anaesthesiologist visits them to assess their condition and opine the manifestation of any side effects from the anaesthesia.

Why are anaesthesiologists needed?

An anesthesiologist allows patients to undergo surgery safely and comfortably without feeling any pain. Anesthesiologists use specialised techniques during surgery to accomplish this, for which they receive special training. For instance, controlled blood pressure lowering during hip surgery decreases bleeding and the need for intra-op or post-op blood transfusions.

Appropriate pain management is required from the patient's standpoint. Proper pain management also helps patients perform physical therapy after the surgery and improves surgical outcomes, especially after many orthopaedic procedures. In addition, good pain management may decrease the rate of heart attacks and other postoperative complications in most patients.

Review

Reviewed by Dr. Manoj Agarwal, Director & Clinical Coordinator, Anaesthesia on 18-Jan 2023.