In neurological disorders, localizing signs pointing to disease of parts of the nervous system may be present e.g, hemiplegia, cranial nerve palsies, focal seizures, etc. Meningitis and subarachnoid hemorrhage are associated with signs of meningeal irritation such as neck rigidity, Kernig’s sign and Brudzinski’s signs. In metabolic coma, localizing signs may be absent. In poisoning, other effects of the poison may also be evident.
1. Routine investigations to exclude systemic disorders include complete urinalysis, estimation of blood sugar urea, electrolytes, blood gases and pH.
2. In suspected poisoning, the gastric materials should be sent for chemical examination for the poison.
3. Cerebrospinal fluid should be examined when meningitis, encephalitis, subarachnoid hemorrage, or meningeal leukemia are suspected.
4. Further tests are decided by the clinical examination and progress of the case EEG, neuroradiology, CT scanning, NMR imaging and radioisotopic scanning may be indicated in many cases.
General Management: Comatose patients are very susceptible to develop several complications as a result of loss of protective reflexes and these have to be prevented. Maintenance of the airway is of utmost importance. The neck has to be kept extended to prevent “falling-back” of the tongue. If necessary a patient airway should be introduced. Secretions have to be removed by postural drainage and suction. In cases with respiratory depression artificial ventilation has to be instituted early. Tracheostomy may be required in some cases.
Maintenance of nutrition and fluid and electrolyte balance: Adequate nutrition (at least 2000 cals/day and 2L of fluid) in the form of milk, sugar, eggs, cereals, salt and water are given through a nasogastric tube. Oral feeding carries the risk of aspiration into the respiratory tract and, therefore, this should be avoided. Parenteral nutrition is started through the intravenous route to supplement nasogastric feeding. The intravenous needle should be maintained aseptically. In prolonged illness, the position of the needle should be changed every 36-48 hours to avoid thrombophlebitis.
Care of the skin: The patients develop bed sores due to continuous pressure on localized areas. This risk is avoided by turning the patient in bed every 2-4 hours and keeping the skin clean and dry. Adequate intake of proteins helps in minimizing the risk of bed sores. When coma is likely to be prolonged, special beds which are capable of turning the patients, and which help in avoiding pressure over localized areas may be used with advantage.
Bladder and bowels: The unconscious patient voids his bladder and bowel automatically and this causes many problems in nursing. Institution of a closed drainage system for the bladder helps in avoiding this soiling of the clothes and prevent infection. Bowels are moved by small enemas or suppositories at regular intervals.
Positioning of the Limbs and physiotherapy: The Limbs should be maintained in optimal positions to avoid fixed deformities. Regular passive movements to the limbs help in preventing venous thrombosis and subsequent pulmonary embolism.
Specific therapy: This depends upon the cause of the Coma. Anticonvulsant medication is indicated if seizures occur. Intercurrent infection (respiratory, urinary or cutaneous has to be treated with antibiotics).
This problem has become important since removal of organs for transplantation is done from patients who are not likely to recover. Patients who are on supportive measures including artificial ventilation may pass into a stage where the cerebral and brain stem functions are irreversibly lost, still the patient may continue to have circulation on account of the supportive measures. Withdrawal of these supports will lead to physical death. The decision to withdraw these supports is a medico-legal one. Therefore, brain death has to be diagnosed with the aid of EEG. Deep Coma without any movement of reflexes for over 12 hours, absence of brain stem reflexes (Oculocephalic reflexes, light reflex and spontaneous respiration) and a flat EEG record indicate irreversible brain damage-the brain death. These criteria are not valid if the coma is the result of overdose of poisons of hypothermia.