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LESS COMMON CAUSES OF CELLULAR INJURY
Hypoxia is the most common and devastating cause of cellular injury. Hypoxia itself is usually caused by hypoperfusion (shock) which can be caused by hemorrhage from trauma, anaphylaxis with loss of peripheral tone, or central failure from the heart (failing as a pump). In the field, however, not all causes of cellular injury are from these.
Other Types of Tissue Injury
Below are other considerations:
Toxicity and Poison
The human cell performs its functions via influx and output of substances it was designed to appropriate, modify, metabolize, or utilize. If there is an "alien" substance which is harmful that enters the cell, it may cause cell malfunction or even impact the structural integrity of it, resulting in destruction. (This concept is also used to advantage with medication.)
Hyperosmolarity is when the concentration of a solute is unbalanced (toward the over-concentated) in a solution, such as in hypernatremia. It can burst the cell.
In high doses, ethanol can be toxic to the liver, pancreas, and kidneys, as well as cause dementia.
Methanol and ethylene glycol
Methanol and ethylene glycol poisoning, even in small amounts, can cause significant toxicity. These are found in coolants, solvents, cleaners, and other industrial products that are ingested to inflict self-harm, by accident (children), or as a substitute for alcohol (ethanol).
The metabolites can cause kidney or liver failure or retinal toxicity (blindness).
Other substances, e.g., chloroform, carbon tetrachloride, and other hepatotoxins cause dose-dependent hepatocellular necrosis ("toxic hepatitis").
Nephrotoxicity (kidney damage) is another outcome. In short, any tissue in the body can be damaged by any substance toxic to its particular function or architecture.
Thiamine and other vitamin deficiency will result in the cell not getting material needed to function. Everything from cognition to clotting can be effected. Malnutrition is more likely a genetic disease, but alcoholism and drug addiction, child abuse, and living in resource-poor living areas can all result in nutritional deficits.
NOTE: In the field, any unusual presentation in a patient who is handicapped or otherwise limited in procuring or consuming a good diet should prompt suspicion of malnutrition as the cause of the complaint.
Thermal and chemical injury to the structural integrity of the cell (membranes, elasticity, etc.) and its contents (nucleus, cytoplasm, organelles) are a toxicity of fluid exchange disruption.
Radiation from cancer therapy will cause cell death and replacement by scarring. Often the sites of injury are areas near sphincters (anus, pylorus, urinary) with associated dysfunctions and obstruction.
Included in this category is the entire range of immunological responses. Cells can be attacked by immunoglobulins, leukocytes and lymphocytes, from exposure to "look-alike" pathogens that are close in structure to one's own cells, labeling both the natives and foreigners "enemies." Rheumatoid arthritis, thyroiditis, and other auto-immune diseases are all types of rejection with provoked destruction.
Infectious processes involve a number of mechanisms that can cause cellular injury. These include direct toxicity (e.g., endotoxins, released when the infecting organism dies; exotoxins, released diredtly by a toxic organism), inflammatory responses, and hijacking of the genetic material to alter protein and enzyme function (viruses).
Whenever tissue is injured to the point of necrosis, it is replaced by scarring--a tough, fibrous matrix which has none of the pliability, elasticity, tone, or function of the cells it replaces.
Medical Child Abuse
Formerly known as Munchhausen by Proxy, this is typically perpetrated by a child's mother or caregiver with exaggerations of a child's symptomatology and a history of frequent emergency room visits. Varied medications can be used to mimic everything from allergies to psychiatric illness. Even though it may not involve actual medication, don't rule out a child being "trained," coaxed, coached, or forced to act a certain way.
Much of the management for these types of cellular injury take place AFTER transport, involving sophisticated protocols and therapies. However, in the field, management must include:
- ABC--airway, breathing, circulation: supportive care.
- Decontamination, via activated charcoal, unless contraindicated.
- Antidotes: based on instructions from the receiving facility and/or Poison Control.
- Enhanced elimination (dialysis, chelation, etcl, usually done at the receiving facility).
Note: emetics that induce vomiting or gastric lavage are controversial and perhaps even contraindicated, since petroleum-based products can cause as much harm coming back up as they did going down. Regarding these techniques, rely on instructions from Poison Control, the receiving facility/doctor, and local EMS protocols.