Unconsciousness is a state where a person is unresponsive to their surroundings and cannot be aroused. It is not a sleep state. Coma is a deep state of prolonged unconsciousness. It is a medical emergency and indicates significant dysfunction of the brain, particularly the parts that control consciousness (the cerebral hemispheres and the reticular activating system in the brainstem). Coma is a symptom of an underlying medical problem, not a disease itself.

Understanding unconsciousness and coma is vital for nurses as these patients require intensive monitoring and specialized care.

Levels of Consciousness

Consciousness exists on a spectrum. While “unconsciousness” is a general term, different levels describe varying degrees of responsiveness:

• Alert: The patient is awake, aware of their surroundings, and responds appropriately to stimuli.

• Lethargic: The patient is drowsy and may fall asleep easily but can be aroused with mild stimuli (like calling their name). They may respond slowly or not fully appropriately.

• Obtunded: The patient is more difficult to arouse and requires stronger stimuli (like light touch or shaking). They are often confused when aroused and may respond to stimuli with one or two words.

• Stuporous: The patient is only aroused by vigorous or painful stimuli (like sternal rub or pressure on a nail bed). Responses are minimal, often limited to groaning or purposeful withdrawal from pain.

• Comatose: The patient is unarousable and unresponsive to even painful stimuli. Reflexes may be present or absent depending on the depth of the coma and the underlying cause.

Coma represents the deepest level of unconsciousness.

Causes of Unconsciousness and Coma

Coma can be caused by anything that severely affects the brain’s ability to maintain consciousness. Causes are broadly categorized:

• Structural Causes: Damage to the brain tissue itself.

  • Stroke (CVA): Large ischemic or hemorrhagic strokes, especially if they affect the brainstem or bilateral cerebral hemispheres.

  • Traumatic Brain Injury (TBI): Severe head injury causing concussion, contusion, hemorrhage (epidural, subdural, intracerebral), or diffuse axonal injury.

  • Brain Tumors: Malignant or benign tumors that cause direct compression, edema, or increased ICP.

  • Brain Infections: Severe meningitis or encephalitis that causes widespread inflammation and brain dysfunction.

  • Brain Abscess: A localized collection of pus in the brain that causes mass effect and inflammation.

  • Hydrocephalus: Buildup of cerebrospinal fluid (CSF) causing increased ICP.

• Metabolic/Toxic Causes: Conditions affecting the brain’s environment or exposure to toxins.

  • Hypoglycemia or Hyperglycemia: Extremely low or high blood glucose levels.

  • Hypoxia/Anoxia: Lack of oxygen to the brain (e.g., cardiac arrest, respiratory failure, carbon monoxide poisoning).

  • Severe Electrolyte Imbalances: Especially severe hyponatremia (low sodium) or hypernatremia (high sodium).

  • Uremia: Severe kidney failure leading to a buildup of waste products in the blood.

  • Hepatic Encephalopathy: Severe liver failure leading to a buildup of toxins (like ammonia) in the blood.

  • Drug Overdose: Especially sedatives, opioids, alcohol, or other central nervous system depressants.

  • Poisoning: Exposure to toxins like heavy metals or certain chemicals.

  • Severe Hypothermia or Hyperthermia: Extremely low or high body temperature.

  • Endocrine Disorders: Severe thyroid dysfunction (myxedema coma, thyroid storm), adrenal crisis.

• Other Causes:

  • Seizures: Prolonged or repeated seizures (status epilepticus) can lead to a postictal (after seizure) state of unconsciousness.

  • Severe Infections (Sepsis): Widespread infection can affect brain function.

  • Shock: Severely low blood pressure leading to inadequate brain perfusion.

  • Post-cardiac Arrest: Brain injury due to lack of oxygen during cardiac arrest.

Pathophysiology

Coma results from the disruption of the normal functioning of the cerebral hemispheres (which are responsible for awareness) and/or the reticular activating system (RAS) located in the brainstem (which is responsible for arousal).

• Bilateral Cerebral Hemisphere Dysfunction: Widespread damage or dysfunction in both cerebral hemispheres, such as from severe global ischemia (lack of blood flow), severe metabolic derangements, or diffuse brain injury, can lead to unconsciousness.

• Brainstem Dysfunction: Damage or compression of the brainstem, where the RAS is located, can directly impair arousal. This can be caused by strokes affecting the brainstem, tumors, or herniation (brain tissue shifting and compressing the brainstem due to increased ICP).

The specific mechanisms leading to brain dysfunction vary with the cause:

• Ischemia/Hypoxia: Lack of oxygen and glucose leads to rapid energy depletion in neurons, failure of cellular pumps, accumulation of toxic substances, and cell death.

• Hemorrhage: Blood causes direct tissue damage, mass effect (compression), and triggers inflammatory responses.

• Increased ICP: Pressure compresses brain tissue and blood vessels, reducing cerebral blood flow and causing ischemia.

• Metabolic Derangements: Abnormal levels of glucose, electrolytes, or toxins disrupt neuronal function by interfering with energy metabolism, neurotransmitter function, or membrane potentials.

• Toxins/Drugs: Directly interfere with neurotransmitter systems or cellular processes in the brain.

Assessment of the Unconscious Patient

Assessing a patient in a coma requires a systematic approach to determine the depth of unconsciousness, identify potential causes, and monitor for changes.

• Level of Consciousness: The most widely used tool is the Glasgow Coma Scale (GCS). The GCS assesses three areas:

  • Eye Opening Response: Spontaneous (4), To voice (3), To pain (2), None (1).

  • Verbal Response: Oriented (5), Confused (4), Inappropriate words (3), Incomprehensible sounds (2), None (1).

  • Motor Response: Obeys commands (6), Localizes to pain (5), Withdraws from pain (4), Abnormal flexion (decorticate) (3), Abnormal extension (decerebrate) (2), None (flaccid) (1). The scores are summed, with a total score ranging from 3 to 15. A GCS score of 8 or less generally indicates coma and the need for airway protection (often intubation). A score of 3 is the lowest possible score.

• Neurological Examination:

  • Pupils: Assess size, shape, equality, and reaction to light. Abnormal findings can indicate specific brain areas affected or the presence of toxins/drugs.

  • Brainstem Reflexes:

    • Doll’s Eyes (Oculocephalic Reflex): When the head is turned to one side, the eyes should move conjugately in the opposite direction (present in intact brainstem). Absent or abnormal movement indicates brainstem dysfunction. (Caution: Do not perform if neck injury is suspected).

    • Cold Calorics (Oculovestibular Reflex): Injecting cold water into the ear canal normally causes eye deviation towards the irrigated ear (present in intact brainstem). Abnormal or absent response indicates brainstem dysfunction. (Performed by a physician).

    • Corneal Reflex: Touching the cornea with a wisp of cotton should cause blinking.

    • Cough and Gag Reflexes: Assess the ability to cough and gag, indicating the function of lower cranial nerves and brainstem.

  • Motor Response: Assess spontaneous movement, response to painful stimuli (withdrawal, localization, abnormal posturing – decorticate or decerebrate), and muscle tone.

  • Breathing Pattern: Observe the rate, rhythm, and depth of respirations. Abnormal patterns (e.g., Cheyne-Stokes, central neurogenic hyperventilation, apneustic, ataxic) can indicate dysfunction in specific brainstem areas.

• Vital Signs: Monitor blood pressure, heart rate, respiratory rate, and temperature. Changes can indicate the underlying cause (e.g., hypertension in hemorrhagic stroke, fever in infection) or complications (e.g., Cushing’s triad – increased BP, decreased HR, irregular respirations – indicating increased ICP).

• Assessment for Signs of Underlying Cause: Look for signs of head trauma, infection, drug use, metabolic abnormalities (e.g., fruity breath in diabetic ketoacidosis), or signs of liver/kidney failure.

Management of the Unconscious Patient

Management focuses on identifying and treating the underlying cause, supporting vital functions, and preventing complications. This is often done in an intensive care unit (ICU).

• Airway, Breathing, and Circulation (ABCs):

  • Airway: Ensure a patent airway. Patients with a GCS of 8 or less typically require endotracheal intubation and mechanical ventilation to protect the airway from aspiration and ensure adequate oxygenation and ventilation.

  • Breathing: Provide oxygen and support ventilation as needed. Monitor oxygen saturation and arterial blood gases.

  • Circulation: Maintain adequate blood pressure to ensure perfusion of the brain and other organs. Administer IV fluids and vasopressors as needed.

• Identify and Treat the Cause:

  • Rapid diagnostic workup (history, physical, imaging, lab tests) to determine the cause.

  • Specific treatments based on the cause (e.g., glucose for hypoglycemia, antidotes for drug overdose, antibiotics for infection, surgery for hemorrhage or tumor, measures to lower ICP).

• Manage Increased Intracranial Pressure (ICP): If increased ICP is suspected or confirmed, interventions include head elevation, midline positioning, avoiding neck flexion, sedation, osmotic diuretics (mannitol, hypertonic saline), and potentially CSF drainage or decompressive surgery. ICP monitoring may be used.

• Temperature Control: Manage fever or hypothermia.

• Seizure Control: Administer anticonvulsant medications if seizures are present or to prevent them in high-risk situations.

• Fluid and Electrolyte Management: Carefully monitor and correct fluid and electrolyte imbalances.

• Nutritional Support: Patients in a prolonged coma will require nutritional support, often via a nasogastric or gastrostomy tube.

Complications of Unconsciousness and Coma

Patients who are unconscious or in a coma are at high risk for developing various complications due to their immobility, loss of protective reflexes, and the underlying medical condition. Preventing these complications is a major focus of nursing care.

• Respiratory Complications:

  • Aspiration Pneumonia: Loss of gag and swallow reflexes increases the risk of aspirating gastric contents or oral secretions into the lungs.

  • Atelectasis: Collapse of lung tissue due to immobility and shallow breathing.

  • Ventilator-Associated Pneumonia (VAP): A risk for patients who are mechanically ventilated.

• Infections:

  • Urinary Tract Infections (UTIs): Common in patients with indwelling urinary catheters.

  • Pneumonia: As mentioned above, often related to aspiration or immobility.

  • Central Line-Associated Bloodstream Infections (CLABSIs): Risk associated with central venous catheters.

• Skin and Musculoskeletal Complications:

  • Pressure Ulcers: Prolonged pressure on bony prominences due to immobility can lead to skin breakdown.

  • Contractures: Shortening of muscles and tendons, leading to limited joint movement, due to prolonged immobility and lack of passive range of motion.

  • Foot Drop: A type of contracture where the foot is permanently plantar flexed.

• Vascular Complications:

  • Deep Vein Thrombosis (DVT): Blood clots forming in the deep veins, usually in the legs, due to immobility.

  • Pulmonary Embolism (PE): A life-threatening condition occurring when a DVT breaks off and travels to the lungs.

• Gastrointestinal Complications:

  • Constipation/Fecal Impaction: Due to immobility, reduced fluid intake, and sometimes medications.

  • Stress Ulcers: Increased risk of gastric ulcers due to physiological stress.

• Ocular Complications:

  • Corneal Abrasion or Ulceration: Due to lack of blinking, dry eyes, or improper eye care.

• Fluid and Electrolyte Imbalances: Can occur due to the underlying cause, medical treatments, or inadequate intake/output monitoring.

• Nutritional Deficiencies: If adequate nutritional support is not provided.

• Psychological Impact: While the patient is unconscious, families experience significant stress, anxiety, and grief.

• Long-Term Neurological Deficits: Depending on the severity and duration of the coma and the underlying cause, patients may have lasting problems with cognitive function, motor skills, communication, or other neurological functions if they recover consciousness.

Nursing Management of the Comatose Patient

Caring for an unconscious patient is labor-intensive and requires meticulous attention to detail to prevent complications and maintain dignity.

• Frequent Neurological Assessment: Perform GCS and neurological checks at regular intervals (e.g., hourly or more frequently depending on the patient’s condition and unit protocol). Report any changes promptly.

• Airway Management: Maintain airway patency. Provide oral care and suctioning as needed. If intubated, provide regular endotracheal tube care and suctioning. Monitor ventilator settings and alarms.

• Respiratory Care: Monitor respiratory rate, rhythm, and depth. Assess breath sounds. Turn and reposition the patient frequently to prevent atelectasis and pneumonia. Provide chest physiotherapy and suctioning as ordered.

• Circulatory Support: Monitor vital signs closely. Administer IV fluids and medications to maintain blood pressure and heart rate. Monitor for signs of deep vein thrombosis (DVT) and implement preventive measures (e.g., sequential compression devices – SCDs, prophylactic anticoagulants as ordered).

• Fluid and Electrolyte Balance: Monitor I&O accurately. Assess hydration status. Monitor laboratory results and administer IV fluids and electrolytes as ordered.

• Skin Care: Implement a strict turning schedule (at least every two hours) to prevent pressure ulcers. Assess skin condition frequently, especially over bony prominences. Keep the skin clean and dry. Use pressure-relieving mattresses and devices.

• Mouth and Eye Care: Provide frequent mouth care to prevent drying and infection. Protect the eyes from drying and corneal damage (e.g., artificial tears, eye patches).

• Bowel and Bladder Management: Assess bowel and bladder function. Patients may require a Foley catheter for urinary drainage. Implement a bowel management program to prevent constipation or impaction.

• Musculoskeletal Care: Perform passive range of motion (ROM) exercises to all extremities to prevent contractures and maintain joint mobility. Use splints or positioning devices as needed. Maintain proper body alignment.

• Nutrition: Administer tube feedings as prescribed. Monitor tolerance and assess for complications (e.g., aspiration, diarrhea, constipation).

• Safety: Implement seizure precautions. Pad the bed rails. Keep the bed in a low position. Protect the patient from injury.

• Temperature Regulation: Monitor body temperature and use cooling or warming measures as needed.

• Infection Control: Use strict aseptic technique for all procedures (e.g., catheter care, suctioning, IV line care) to prevent infections.

• Emotional Support: Although the patient is unconscious, talk to them as if they can hear you. Explain what you are doing. Provide a calm and quiet environment. Offer support and information to the family. Encourage family presence and participation in care as appropriate.

• Communication: Communicate with the patient by talking to them. Communicate effectively with other members of the healthcare team about the patient’s status and any changes.