Medical toxicology and critical care are linked like the Rod of Asclepius. This evidence dates back to the Middle Ages: Moses Maimonides's Treatise on Poison and Their Antidotes from the late 12th century [1]. Intensive care physicians who treat poisoned patients should utilise a comprehensive examination and management strategy. Accidental or purposeful poisoning with both legal and illegal chemicals can result in a diverse array of symptoms and clinical manifestations. Consequently, the relevance of the patient's medical history and physical examination in detecting a poisoned patient cannot be overstated. Initial treatment should focus on stabilising the patient's condition and providing supportive care until the offending drug is discovered. The plan of action is to offer supportive care, avoid toxin absorption, administer antidotes when necessary and improve excretion procedures.

Supportive Care

Airway Administration

The necessity to secure the airway is dictated by the absence of airway-protective reflexes, concern for aspiration or the presence of respiratory failure. The optimal method for securing the airway is Rapid Sequence Intubation (RSI) with preoxygenation and neuromuscular inhibition, unless the patient is already dead [2]. This should be performed by tracheal intubation [3]. Due to an inability to appropriately preoxygenate the patient or worries that the patient may be difficult to intubate, it is necessary to examine alternatives to RSI. The alternative to Rapid Sequence Intubation (RSI) is Delayed Sequence Intubation (DSI). It consists of providing sedatives that do not impair airway reflexes, followed by a brief interval of preoxygenation and then paralytics [4]. If feasible, orotracheal intubation is recommended to nasotracheal intubation for several reasons. Nasotracheal intubation is technically more difficult and increases the prevalence of sinusitis, purulent and serous otitis and ventilator-associated pneumonia compared to orotracheal intubation. An alternative technique for securing the airway and the instruments to construct a surgical airway (cricothyrotomy) must be readily accessible.

Respiratory Assistance

Multiple poisons impede oxygenation and ventilation. Consequently, the adequacy of respiration must be checked as soon as the airway is secured [5]. A lung-protective strategy should be implemented while establishing the ventilator settings [6]. Strategies for lung protection avoid the development of ARDS due to barotrauma and oxygen poisoning. Although these techniques are widely utilised in the ICU, they have not been examined in the poisoned patient population [7].

Circulation and Hemodynamics

After creating an airway and sustaining respiratory function, assessing the patient's circulatory state is the next step. Cardiovascular abnormalities often observed in poisoned patients include hypertension, hypotension, cardiac arrhythmias and conduction disruptions.

The poisoned patient's elevated blood pressure may or may not be the consequence of exposure to any of a variety of chemicals. The most common reasons of increased blood pressure include withdrawal (benzodiazepine or ethanol withdrawal), termination of a medically prescribed medicine producing rebound hypertension, such as clonidine or minoxidil and insufficiently treated or untreated underlying hypertension [8]. The underlying cause of hypertension determines its therapy. When hypertension is induced by medicines having direct adrenergic action, such as amphetamines, ephedrine or pseudoephedrine, direct vasodilators like phentolamine or nitroprusside should be investigated [9]. When hypertension is induced by medicines with indirect adrenergic action or drug withdrawal, benzodiazepines should be used for sedation [10].

Abnormal hemoglobins (such as methemoglobin, sulfhemoglobin or carboxyhemoglobin) and toxins that disrupt the mitochondrial electron transport chain (such as cyanide, hydrogen sulphide or sodium azide) impede the utilisation of oxygen at the molecular level [11], resulting in histotoxic hypoxia and shock. Frequently, an elevated plasma lactate concentration accompanies metabolic acidosis as an indicator of these toxicities [12].

The Lipid Emulsion Therapy (LET) is one of the most recent developments in the treatment of poisoned patients in severe condition. It was administered to patients suffering from local anaesthetic toxicity. It has also been utilised in the treatment of various types of poisoning. LET has been reported to reverse the harmful effects of calcium channel antagonists, tricyclic antidepressants, benzodiazepines, anticonvulsants and -adrenergic blocking drugs [13]. Extracorporeal Membrane Oxygenation (ECMO) is recommended for poisoned individuals in refractory shock who do not respond to standard therapy.

In individuals who have been poisoned, ECMO acts as a bridge until the poisons are digested or eliminated [14], at which point the patient should resume normal circulatory function. Recent technological developments have made Extracorporeal Membrane Oxygenation (ECMO) a more viable option for patients with refractory shock, despite its increased cost and deleterious consequences.

Decontamination

Gastrointestinal Decontamination

Once a standard in the treatment of poisoning, gastrointestinal (GI) decontamination is no longer advised. In general, it is considered for patients who appear extremely early (less than an hour after consumption) or who have taken a very big or severe overdose and for whom there is no antidote. Ideally, GI decontamination would reduce absorption of several ingested poisons, however its usage is not connected with better outcomes (e.g., mortality, length of stay) [15]. If GI decontamination is tried, it should be performed in the emergency department as soon as feasible. It is quite improbable that the patient will benefit from decontamination if it is initiated in the ICU.

The Use of Activated Charcoal

As a decontaminant, activated charcoal is widely employed. In a two-step procedure, different carbonaceous materials are pyrolyzed and subsequently treated at high temperatures with oxidising agents such as steam or carbon dioxide to "activate" it and improve its adsorbent capacity. Activated charcoal adsorbs toxins inside the GI lumen and transports them along the GI tract, therefore preventing their absorption [16]. It does not absorb metals, corrosives or alcohols well. The choice to provide activated charcoal needs a patient-specific risk assessment and is not considered standard care [17].

Total Colon Irrigation

Whole Bowel Irrigation (WBI) is a detoxification treatment that increases the flow of toxins through the digestive tract. It can be accomplished by inserting a nasogastric or orogastric tube and delivering substantial quantities (1-2 L/hour) of osmotically balanced polyethylene glycol solution (PEG) until the patient passes at least two clear, liquid stools. In contrast to other methods of GI cleansing, WBI can be initiated or continued in the ICU. Traditionally, WBI is used to treat body packers. Body packers are individuals who take massive quantities of illegal narcotics for transporting purposes. Lethal doses of the medicine can be absorbed into the body packers' systems in the event of an unintentional packet leak, which can be life-threatening. Given the life-threatening risk associated with even a single packet leaking, WBI should be launched to remove the packets as quickly as feasible. Contraindications include people with ileus, blockage or gastrointestinal tract damage [18].

Elimination

Multiple-Dose Activated Carbon

Multidose Activated Charcoal (MDAC) is utilised to facilitate the removal of ingested poisons. Multidose activated charcoal may be beneficial for people at risk of delayed absorption owing to the consumption of delayed-release medications. MDAC may potentially aid patients who absorb toxins that transit enteroenteric or enterohepatic circulation. In enterohepatic circulation, chemicals are reabsorbed after being produced into the bile and subsequently the small intestine. In enteroenteric circulation, chemicals are reabsorbed after being released into the gut. By providing MDAC, charcoal can absorb toxins produced into the colon before they are reabsorbed, hence facilitating removal [19]. After the initial normal dose of charcoal, multidose activated charcoal is typically supplied at a dosage of 0.5 g/kg [20].

Urine Alkalinization

Alkaline urine promotes ionisation of acidotic medicines inside renal tubules, hence reducing resorption of the ionised drug across the renal tubular epithelium and boosting excretion by urine [21]. Urine alkalinization is especially effective against weak acids such as salicylate and phenobarbital. Hypokalemia, renal dysfunction and fluid overload are contraindications for urine alkalinization.

Extracorporeal Removal

Poisoned patients have limited indications for extracorporeal removal procedures, such as hemodialysis, hemofiltration and continuous renal replacement therapy. To be successfully eliminated by an extracorporeal approach, a toxin must possess a number of characteristics, including a low volume of distribution (VD 1 L/kg), low molecular weight, poor protein-binding capability and low endogenous clearance [22].

Ancillary Support

Poisoned ICU patients who are bedridden for an extended period of time are at risk for venous thromboembolic illness. Despite receiving prophylaxis, around 33% of ICU patients develop ultrasonographically identifiable Deep Venous Thrombosis (DVT). The use of heparin or pneumatic compression stockings reduces the incidence of DVT by at least 50 percent, according to meta-analyses [23]. If a protracted ICU stay is expected, prophylaxis for deep venous thrombosis should be commenced with unfractionated heparin, low-molecular-weight heparin or compression devices as soon as the patient is in. The objective of nutritional assistance is to satisfy the dietary demands of the patient without overfeeding. Avoid overfeeding since excessive carbohydrate consumption might increase carbon dioxide generation. The enteral route is recommended over the parenteral route because it helps maintain the integrity of the mucosal barrier in the stomach [24].

As critical care physicians, we frequently treat patients who have been poisoned. The vast majority of these individuals will merely require monitoring and they seldom develop toxicity. However, immediate care is necessary for individuals who present with substantial adverse consequences. First, as with any severely sick patient, the airway, breathing and circulation must be stabilised. Identifying the poison through the patient's medical history, toxidrome or laboratory testing may lead clinicians in the proper direction. Antidotes can be utilised when the particular toxic agent is identified. Our government has a National Poison Information Centre (NPIC) that is a key element of the Poison Control Programme and gives physicians with 24X7 access to vital information through telephone. After describing the drug ingested by the patient, the NPIC will provide a probable diagnosis, instructions for emergency care, the antidote and if possible, the source of the antidote.

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