Is it common to experience poisoning?
Clinical Professor David Ranson, Deputy Director – Head of Forensic Services, Victorian Institute of Forensic Medicine, explains,
“Poisoning covers a wide spectrum of substances and encompasses a variety of very different circumstances. As a community, we talk about poisoning in a lay sense as being chemicals that are toxic to the body. Actually, poisoning covers a broad range of substances which can involve inorganic poisons, organic poisons, traditional illicit drugs, synthetic drugs, high levels of prescribed drugs, prescribed drugs in normal amounts which are toxic in some individuals, and prescribed drugs which are not toxic in others.
“Although the media and television dramas tend to imply that deliberate homicidal poisonings happen all the time, the truth is that these cases are extremely rare in the real world. Excluding all cases of suicidal drug overdoses, in terms of forensic practice and the coroner’s cases, it is relatively uncommon to see poisoning as a cause of death, either deliberately or accidentally.”
However, when investigating the circumstances of poisonings, we see that this happens in a variety of ways. Prof Ranson says that poisoning is more common in cases of suicide by drug overdose, when a person addicted to drugs suffers an accidental overdose, when the wrong dose of a drug (or the wrong drug) was administered by medical staff, or when the wrong dose of a prescribed drug was taken by a patient.
“When we talk about poisons, we need to consider all these different categories of poisoning. There can also be cases when an individual experiences poisoning when taking a prescribed drug which has never caused complications previously, but a change in their disease status has made them more vulnerable to the drug.”
Prof Ranson explains that there are some diseases (liver or kidney disease) where a patient may experience an increase in their blood level of a particular drug if they are no longer able to metabolise or excrete that drug in the normal way. “A dose that may be perfectly safe for someone in their 40’s, suddenly becomes a dangerous dose to someone in their 80’s with liver dysfunction or kidney dysfunction. Pathology is absolutely crucial in understanding the nature of the disease and establishing a person’s level of risk in relation to developing a toxic effect from a drug.
“In addition, nursing homes can sometimes be an environment where an individual takes or is given a drug accidentally that belonged to someone else and it is a hazard to them. This can be the case, particularly where you have an individual who is on a pain medication with a narcotic agent, such as morphine. Due to the patient’s pain level, they may be on a substantial amount of prescribed drugs; however they can cope with it because they have been taking it regularly. If someone else takes or is given that drug accidentally when they are not used to receiving it, they can die from a massive overdose or suffer severe consequences.”
Prof Ranson explains that the poison control system in Australia, and in most western countries, is sophisticated in terms of detecting poisoning and also dealing with a clinical setting in which poisoning occurs.
“The poison centres provide urgent information to emergency departments and intensive care departments on the nature of a drug. Occasionally, if it is an unusual drug that may have been taken, and the clinician wants real levels of the drug, they may send specimens to forensic centres for analysis as they normally have a greater capacity to look at a wider range of toxic substances. In hospitals and in clinical settings, the focus is on what needs to be tested in order to manage the patient. In other words, it may not be that important to know the level of the drug, as a patient is often best managed symptomatically.
Prof Ranson explains that understanding the nature of the pathology of different disease states at autopsy can be crucial as what is found in a death investigation may well alter how a drug level in the body is interpreted.
The redistribution of drugs is an extremely important issue for the forensic pathologist and the forensic toxicologist.
“Forensic testing or testing after death can be problematic in terms of the levels recorded. The clinical level in life may not always represent the level you will see in post mortem blood. After death, due to the redistribution of some drugs from body tissues back into the blood, the blood levels of a drug can artefactually increase, therefore it can look like someone has taken a very significant drug overdose, but in fact it’s due to the redistribution of drug after death.”
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This article appeared in the February 2018 Edition of ePathWay which is an online magazine produced by the Royal College of Pathologists of Australasia (http://www.rcpa.edu.au/Library/Publications/ePathway).
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