Page 621 - ACCCN's Critical Care Nursing

598 S P E C I A LT Y P R A C T I C E I N C R I T I C A L C A R E

to avoid an obviously unpleasant experience. Although Contaminated linen and clothes should be sealed in a
conservative management with observation is appropri- bag and destroyed. 108,111
ate in certain situations, the risk of not treating might be
104
greater in others. If a large number of tablets or pills MANAGEMENT: ENHANCING TOXIN
are consumed at one time, they may clump together in ELIMINATION FROM THE BLOOD
the stomach and form a mass that is too large to pass out
of the pylorus (e.g. aspirin). 115 After a substance has entered the bloodstream, it is nor-
mally excreted from the body either in an unchanged
Once a substance enters the lower gastrointestinal tract, form or after liver metabolism and detoxification. Various
it can be absorbed into the mesenteric circulation. As metabolic byproducts are eliminated in the bile and
absorption can vary according to substance, slow-release faeces or urine. Urinary excretion of substances can be
characteristics, rate of peristalsis and the presence of other enhanced by increasing the filtration process (i.e. forced
substances, it is possible for a poison to be present in the diuresis: large volumes of IV solutions and/or diuretics),
bowel for an extended period of time. If intestinal motil- by inhibiting absorption in the renal tubules, or by stimu-
ity can be stimulated or the toxin permanently bound lating the secretion of substances into the urine. 108-110
until excretion, then further absorption is reduced. 108
Alkalinisation of Urine
Activated charcoal is a refined product with an enor-
mous surface area that binds to a large range of sub- Manipulation of the absorption or secretion process of a
stances to enhance elimination, and is the most effective drug can be assisted by chemically altering the structure
decontaminating agent currently available, when given of some substances. All substances break down into ions
early after ingestion. 107,108,110 A solution of either water at a specific pH for that substance. Altering the pH of
or sorbitol is mixed with 15–30 g of activated charcoal urine with acidifying or alkalising drugs allows the poison
to form a thick, liquid slurry which is given to a com- to be forced into an ion state and then excreted in the
pliant patient orally or through a nasogastric tube. It urine. This ‘ion trapping’ process is effective only for sub-
may be mixed with a cathartic, which reduces the time stances that are primarily eliminated by the kidneys 108-110
the substance or the charcoal is in contact with the (e.g. salicylates, tricyclic antidepressants have increased
bowel wall, although there is no evidence that this excretion due to urinary alkalisation). 104
116
improves clinical outcome. Effectiveness can be
improved through repeated administration of activated Haemodialysis or Haemoperfusion
charcoal, ensuring that the entire drug is absorbed, and If a dangerous amount of a poison is present or if renal
interrupting the drug reabsorption in the enterohepatic failure is evident, then haemodialysis or haemoperfusion
104
circulation. Cathartic agents such as sorbitol and poly- may be used to promote excretion. Dialysis is effective
ethylene glycol reduce gastric transit time; in theory in removing only substances that are reversibly bound
this limits absorption, although this has not significantly to serum proteins, or not stored in body fat. This is a
improved outcomes. 103,104 Unfortunately, not all poisons highly invasive approach and is normally reserved for
that are ingested can be bound by charcoal (e.g. alcohol, life-threatening cases (see Chapter 18 for further
heavy metals). 107,108,110 discussion). 107,108,110

Inhaled Poisons MANAGEMENT: PREVENTING
A patient poisoned by inhalation of toxic gases or powders COMPLICATIONS AND SPECIFIC
should be removed from the source as soon as it is safe SYMPTOMATIC CARE
to do so. Attempts to remove the substance, which is Supportive care is the key element in managing an acutely
usually a vapour, gas or fine particulate matter, from the poisoned patient. Once a patient has either ingested or
104
lungs are not normally useful. Staff involved in direct been exposed to many poisons, there are limited options
patient care should use contact precautions to reduce other than to treat the symptoms as they present or
their own contamination risks with unknown substances. become clinically significant (see Table 22.7).
Clothing for many inhaled poisons may contain signifi-
cant amounts of the poison and serve as a continuous Antidotes act to antagonise, compete with or override the
source of the toxin. Contaminated linen and clothes effects of the poison, although few specific antidotes exist
should be removed carefully, sealed in a bag and for toxins (see Table 22.8). In some cases, an absorbed
destroyed. 108,111 toxin can be rendered benign by the use of an antidote
(e.g. the interaction between naloxone and opiates).
104
Contact Poisons For chelating agents (desferrioxamine for iron poison-
Contact poisons are dangerous because of their ability to ing), a non-toxic compound is formed and safely elimi-
The effect of an antidote may
nated from the body.
107,108,110
enter the body via the skin or mucous membranes. All be only temporary if it has a shorter half-life than the
clothing and all of the toxic substance should be carefully poison. Most antidotes are given either in a specific dose
removed, preferably with an irrigating and neutralising or as a response to dose rate. 104
solution. Contact precautions to avoid direct skin contact
and reduce the risk of self-contamination are used. Cloth- For many poisonings, symptomatic care involves support
ing may contain significant residual amounts of the and protection of vital organ systems; frequent physical
poison and serve as a continuous source of the toxin. assessment of respiratory, cardiovascular and renal