Part VIII. CERTAIN EMERGENCY AND ACUTE POISONING CONDITION

Chapter 58. Coma

An impairment of consciousness is understood as a disorder of environment, objects, events and their connections reflection, that is manifested in complete inability or indistinctness of external stimuli perception, disorientation in time and place, and incoherent thinking. The degree of consciousness impairment often plays a decisive role in the outcome of many disorders and pathological processes. Therefore, one of the key points to consider when examining a patient, in particular in emergency setting, is determination of his/her state of consciousness. Consciousness violations are usually divided into two groups.

• Changed consciousness is a productive form of consciousness impairment that develops during wakefulness and is characterized by mental function deterioration, perverted perception of reality and the subject’s own personality, and usually not accompanied by immobility. This form of consciousness impairment is a leading manifestation of most mental diseases and is covered by psychiatry. These forms include:

1) delirium is an acute consciousness violation with a disorientation to place and time, but with a preserved orientation to self. The causes for delirium are as
follows:

• neurological diseases (epilepsy, multiple sclerosis, Alzheimer’s disease, acute circulatory disorders, etc.);
• CVD (hypertensive encephalopathy, severe heart rhythm and conduction disturbances, MI etc.);
• severe infections (encephalitis, meningitis, brain abscess, tularemia, etc.);
• injuries (traumatic brain injuries, burns, electric trauma, heat and sunstroke);
• hypoxia (chronic obstructive pulmonary disease, pneumonia, heart failure, etc.);
• poisoning (alcohol, methanol, drugs, carbon monoxide, insecticides, etc.);
• malignant brain diseases;
• metabolic disorders (high fever, hypoglycemia, liver failure, etc.);
• overdose of medications (atropine and its derivatives, benzodiazepines, barbiturates, sleeping pills, antihistamines, GCs, etc.);
• mental illness;

2) oneiroid is a disturbance of consciousness with involuntarily arising dream-like and fantastic representations and vivid hallucinations in the form of completed by content scenes following in a certain sequence and forming a single whole that is associated with partial or complete disconnection of the patient from the surrounding reality;

Table 58.1. Diagnosing delirium using the Confusion Assess Method (CAM)

3) amentia is a form of consciousness disturbance with a predominance of confusion, incoherent thinking, speech and movements.

• Depression of consciousness includes unproductive forms of consciousness disorders characterized by lack of mental activity with a decreased level of wakefulness, a distinct suppression of intellectual function and motor activity. As a rule, this condition occurs due to morphological changes or sudden violations of brain metabolism.

Classification

In domestic clinical practice, consciousness level assessment is performed according to the conventional classification of consciousness disorders developed by A. N. Konovalov et al. (1982) and recommended as working formulation.

• Clear consciousness is characterized by wakefulness, active attention, and ability to full speech contact. The patient comprehends the questions and gives adequate answers, executes commands fully and quickly, opens his eyes spontaneously. A quick and purposeful response to any stimulus, with preservation of all types of orientation (to self, place, time, surrounding people, situation, etc.), and appropriate behavior are observed. Retro- and anterograde amnesia is possible.
• Obtundation is a stage of consciousness depression characterized by increased threshold of all external stimuli, deceleration and hindering of the natural stream of mental processes, incompleteness or lack of orientation in the environment.
• In obtundation, the increased sensitivity threshold to all stimuli primarily means decreased attention, i.e. the ability of a person to select the necessary information and coordinate responses so as not to disrupt the logical sequence of thoughts and actions.
• Obtundation has two gradations.
  • Moderate obtundation (somnolence; from the Latin somnolentus — “lethargy”). Moderate obtundation is characterized by psychic inhibition, lethargy, difficulties in verbal contact with the person; the patient is able to execute all commands, but slowly and with impaired movement coordination as a result of reduced attention (for instance, missing during the finger-to-nose test); partial disorientation may appear.
  • Deep obtundation (stupor; from the Latin stupor — “insensibility, immobility”). Deep obtundation is characterized by short-term, only possible after physical stimuli (patting on the cheeks, exposure to ammonia vapors, rubbing the ears), often monosyllabic “yes–no” verbal contact with a person, disorientation (the patient does not recognize close relatives, sometimes is unable to tell his/her name); likely involuntary urination and defecation.
• Sopor (from the Latin sopor — “unconsciousness”) is a stage of a patient’s consciousness depression characterized by the absence of response to verbal stimuli while maintaining reactions to stimuli such as pain.
• Sopor is characterized by complete inability to rouse, lack of speech contact and inability to execute any commands. All physiological reflexes are fully preserved (when there are no specific causes for their violation). Respiratory and hemodynamic parameters are normal.
• The main difference between sopor and surface coma is preserved protective coordinated reactions to irritative stimuli (e.g., to pain or the smell of ammonia). The patient in a state of sopor can determine the stimulus location and eliminate it with a coordinated movement (e.g., push away the cotton wool with ammonia, turn on his/her side, open his/her eyes) that suggests preserved cortical-spinal connection.
• Coma (from the Greek koma — “deep sleep”) is a state of deep CNS depression characterized by complete loss of consciousness, any response to external stimuli, and disorders of vital body functions regulation.
  • Moderate coma (I). Reactions to any external stimuli (except for severe pain) are absent. Pain response may include extension-flexion limb movements, tonic convulsions with a tendency to generalization. Sometimes, facial expressions of suffering appear. In contrast to sopor, protective motor reactions in coma (I) are not coordinated, not purposeful in eliminating the stimulus. The patient does not open his eyes in response to painful stimuli. Pupillary and corneal reflexes are usually preserved, abdominal reflexes are depressed, tendon reflexes more often over-expressed. Oral automatism and pathological pedal reflexes appear. Swallowing is very difficult. The protective reflexes of the upper motor pathways are preserved to a certain extent. Pelvic sphincters control is impaired. Respiratory and cardiovascular system functions are relatively stable with no sharp deviations.
  • Deep coma (II). In contrast to the coma (I), protective reactions to pain and protective reflexes (corneal, pharyngeal, cough) are absent. Muscle tone is decreased; in this regard, in patients with meningeal syndrome, it is difficult to identify neck stiffness, but it is possible to detect a positive Kernig symptom. Hemodynamics may be normal, or there may be a tendency to arterial hypotension. Respiratory function impairment with the development of respiratory failure (tachypnea, respiratory movements rhythm disruptions, skin and mucous membranes cyanosis) is possible.
  • Extreme coma (III). The patient is found to have bilateral extreme mydriasis, and the eyeballs are motionless. Total areflexia, diffuse muscle atony, gross vital functions violation — respiratory rate and rhythm disorders, sharp tachycardia — are found. BP is critical or not detected. The so-called Glasgow coma scale (Table 58.2) is well-established for determining the degree of consciousness depression. According to the Glasgow coma scale, the patient’s condition is assessed against the points on three elements of the scale. Points are summed up.