General anaesthesia literally means inducing unconsciousness in patients before they undergo surgical or certain other medical procedures, says Dr Selvakumar, Anaesthesiologist of KG Hospital.
He was delivering a lecture on “General anaesthesia” for the benefit of the post-graduate students of KG Hospital and Post Graduate Institute at the hospital Auditorium recently.
Dr Selvakumar said that general anaesthesia procedure was generally known by the triad: Unconsciousness, Analgesia and Muscle relaxation (or skeletal muscle relaxation). The first two procedures may not be enough to go inside the cavities such as thoracic cavity and peritoneal cavity.
- He laid stress on the point that for reaching the cavities an anesthesiologist needed a good muscle relaxation agent. Dr Selvakumar pointed out that recently a fourth procedure called “Controlling of ophthalmic nerves” had been added to the triad.
During drug administration, the anaesthesiologist might face physical conditions like tachycardia and hypertension in patients. Explaining the first procedure in the triad, ie., unconsciousness, Dr Selvakumar said that it could be induced either by intravenous anaesthetic agents or inhalation anaesthetic agents.
He cautioned that the intravenous anaesthetic agents would render the patient unconscious within 17—20 seconds. Its effect on the patient would be so rapid that the anaesthesiologist should be prepared for the next plan of action. By no account, intravenous anaesthesia be administered outside the operation theatre or by a less experienced anaesthesiologist.
Dr Selvakumar said that the inhalation anaesthesia is about 170 years old. About 2 decades ago, the mortality rate in patients under anaesthesia was quite significant. But nowadays, the anaesthesia-related mortality rate was very negligible.
He noted that “ether is an anaesthetic agent, but it is neither a pain reliever nor a muscle relaxant. Now, we get better muscle relaxants.” About analgesia, Dr Selvakumar said that this procedure was being adopted based on five vital signs such as 1. Pulse, 2. Temperature, 3. Respiration, 4. Blood pressure and 5. Pain.
Definition of pain
The International Association for the Study of Pain had given the following definition for pain: “It is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.”
Dr Selvakumar said that “initially pain might manifest in sensory form and if it persists it will acquire emotional characteristics. If there is chronic pain for six weeks it is difficult to treat. So, the anaesthesiologist has to treat chronic pain by giving appropriate analgesia.”
In this context Dr Selvakumar presented the “Comparative pain scale” with severity ranging from 0 to 50 on the pain scale. On the top of the scale are labour pain and traumatic pain, followed by amputation of digit, chronic back pain, cancer pain, phantom limb pain, bruise, fracture, cut, laceration and sprain, and at the bottom of the scale are toothache and arthritis.
Labour analgesia methods
- About the labour analgesia methods, Dr Selvakumar explained that only 85 per cent of mothers experience labour pain. The choice of analgesia in such cases would depend on the medical condition of the patient, progress of the labour and resources and facility available in the labour room.
He said that the TENS (Transcutaneous Electrical Nerve Stimulation) was his favourite procedure in which there was no need for drugs. Though the TENS procedure would not give complete relief it would give about 70 per cent relief.
In labour cases non pharmacological procedures such as known midwifery, supportive partner, massage, water bath, aroma therapy and acupuncture could be adopted. Anaesthesia is given in non surgical cases such as shoulder dislocation, hip dislocation, MRI and ECG,” Dr Sevakumar added.