ORGANOPHOSPHATE POISONING
Introduction
Case fatality for self-poisoning in the developing world is around 10-20% according to some estimates; but for certain pesticides it may be several times higher. Such pesticides often contain organophosphates, which are highly toxic compounds. They cause problems by leading to an imbalance of chemical transmitters at nerve endings. This in turn can result in severe or even fatal symptoms for the patient. Organophosphate poisoning is now rarely seen in the UK; the use of these compounds is restricted to agricultural rather than residential pesticides. But in parts of the developing world, where much of the population lives in rural agricultural areas, it is seen more frequently. Many of the patients at the Clinics we serve in Zambia live and work in farming communities. The Virtual Doctors team has consulted on a number of cases of deliberate self-poisoning with organophosphate containing pesticides; with a further three incidents in the last quarter alone.
Credit: Adwo-Shutterstock.com
The onset of symptoms following ingestion of an organophosphate will vary between people (and between pesticides), but it is usually within minutes to hours. Mild exposure may lead to a syndrome rather like flu (runny nose, fatigue, dizziness etc). More significant exposure may cause vomiting, diarrhoea and cramping abdominal pain. The patient may complain of burning of the mouth or throat and may describe chest tightness. Subsequently there may be fasciculation (muscle twitching) then weakness, fits and confusion followed by organ failure and even death.
Even if the patient survives the acute effects of the poisoning, there may be further complications afterwards:
Muscle weakness (1-5 days after poisoning)
Organophosphate-induced nerve injury (1-5 weeks after ingestion)
Chronic organophosphate induced neuropsychiatric disorder
Given the severity of the condition, many patients will need transfer to a Hospital for ongoing management. Nevertheless, the early identification of potential cases in the community and swift emergency management at the Clinic can help to save lives
The Case
We present a case of deliberate self-poisoning, trying to outline the steps where the Virtual Doctors can offer help and support.
A 47-year old man is brought to the clinic after taking an unknown substance in an attempt to kill himself. He is extremely unwell on arrival with noisy breathing and a slow weak pulse. His blood pressure is dangerously low, and he is only semi-conscious.
When managing the sick patient, it is sensible to use a structured approach. The ‘ABC’ assessment of emergencies is helpful: the clinician checks and manages problems relating to:
· Airway
· Breathing
· Circulation
· Disability (the patient’s conscious level)
And then moves on to:
· Exposure (looking at everything else)
This checklist forms part of an ongoing continuous assessment, as the response to immediate therapy is monitored.
In our Case responses to the Clinical Officers we try to emphasise and encourage this approach. In addition, we have recommended various educational resources covering the ABC assessment of the sick patient and produced our own podcast on the topic. We hope to help them incorporate this into their own practice, for every emergency they see. It helps clinicians address the most life-threatening problems first and makes sure nothing is overlooked. It helps to prepare them to deal with challenging cases even before contacting us.
The Clinical Officer begins her initial ABC management. The patient has copious secretions around his mouth, but his airway is not obstructed. There is no oxygen immediately available, but the CO has been successful in putting in an IV line and giving fluid to support the circulation. She gives him a dose of atropine in view of his low heart rate. She has also given some dextrose intravenously in case a low sugar level was making the patient drowsy.
The management of poisoning mostly centres around optimal supportive care. We have provided a checklist to the clinical officers on the forum relating specifically to generic supportive care of the poisoned patient.
The Clinical Officer is concerned that, despite her initial management, the patient remains gravely unwell. She contacts the Virtual Doctors via the App for further support.
The Volunteer emphasises the need for “ABC” management initially. They recognise from the patient’s presentation that it is highly likely that this patient has taken an organophosphate compound (the slow heart rate and excessive salivation in this drowsy and unstable patient are clues). This is important because in cases of organophosphate poisoning there is a specific antidote: atropine. It is one of only 4 antidotes listed on the Zambian Essential Medicine Formulary. The volunteer explains the specific management to the Clinical Officer: in such severe cases of poisoning a single dose of atropine will not be sufficient; repeated doses (often followed by an infusion) are required. This can be life-saving. The Volunteer gives a clear description for the targets of treatment (and also highlights the side effects of too much atropine). The Volunteer recommends giving another medication, pralidoxime, to avoid further complications, if it is available. They stress the importance of re-assessing “ABC” at each step and highlight that the patient needs close observations.
The Clinical Officer follows this advice and the patient’s vital signs improve. She contacts the team again to let us know things are beginning to stabilise.
Even if there is not a specific antidote available, it is always helpful in cases of poisoning to know what problems to look out for; in the UK we have an online resource called Toxbase run by the National Poisons Information Service. Our volunteers can refer to this when advising on a case (in the meantime, we have made our COs aware of other reliable resources that they can access locally online to provide them with basic information about specific poisons). Such databases highlight what complications to expect not only at the time of the acute poisoning but also subsequently. In the case of organophosphate poisoning there is an ongoing danger period and the Volunteer ensured that the CO knew what symptoms and signs to be vigilant for; specifically, weakness of the neck and breathing muscles, that can be life-threatening.
The following day a further message told us that the patient was much better; he was awake and alert with a normal blood pressure and pulse rate.
We are not able to measure the benefit our service offers in terms of sense of teamwork or even moral support, but there is no doubt it is important. The Clinical Officer was relieved to have someone to discuss the progress of the patient with and the Volunteer was extremely encouraging about all her inputs and efforts so far.
It is likely that the patient with organophosphate poisoning will need transfer to a hospital where continuous monitoring and ventilatory support is possible. But initial prompt resuscitation and atropine administration, along with optimal supportive care prior to transfer, probably saves many lives. So, the early management at the local facility is still of vital importance and the Virtual Doctors team tries to support that at every step.
But our input does not always end at the time of transfer. It is not unusual for our team to be contacted after the patient has been moved to hospital. Dealing with a case of severe self-poisoning can be quite challenging both clinically and emotionally and we have been sent referrals following transfer asking, “Could I have done anything else?” Our main role then is as a mentor and to debrief. We can also share available educational resources with them (in this case there is a topic relating specifically to organophosphate poisoning on the forum). Reflecting and learning from cases like this is really important. We have recently started posting weekly Case-based problems on the forum so that we can share learning from these episodes with all the Clinical Officers. Over time we hope to build a significant case series for the whole team.
In this way the Virtual Doctors Charity aims to improve knowledge and skills which will empower the Clinical Officers to manage the cases themselves, as well as providing clinical advice and mentoring during and after a case encounter.