Hyperpyrexia and hypoglycemia are more frequently observed in children than in adults due to salicylate poisoning. Both adults and children may experience common clinical manifestations such as nausea, vomiting, tinnitus, deafness, sweating, dehydration, hyperventilation, and cutaneous flushing. However, it is important to note that xanthopsia is associated with digoxin toxicity, not salicylate poisoning.

The Royal College of Emergency Medicine (RCEM) recognizes four antidotes that can be used to treat cyanide poisoning: Hydroxycobalamin, Sodium thiosulphate, Sodium nitrite, and Dicobalt edetate. When managing cyanide toxicity, it is important to provide supportive treatment using the ABCDE approach. This includes administering supplemental high flow oxygen, providing hemodynamic support (including the use of inotropes if necessary), and administering the appropriate antidotes. In the UK, these four antidotes should be readily available in Emergency Departments according to the RCEM/NPIS guideline on antidote availability. Hydroxocobalamin followed by sodium thiosulphate is generally the preferred treatment if both options are available. Healthcare workers should be aware that patients with cyanide poisoning may expel HCN through vomit and skin, so it is crucial to use appropriate personal protective equipment when caring for these patients.

Further Reading:

Burn injuries can be classified based on their type (degree, partial thickness or full thickness), extent as a percentage of total body surface area (TBSA), and severity (minor, moderate, major/severe). Severe burns are defined as a >10% TBSA in a child and >15% TBSA in an adult.

When assessing a burn, it is important to consider airway injury, carbon monoxide poisoning, type of burn, extent of burn, special considerations, and fluid status. Special considerations may include head and neck burns, circumferential burns, thorax burns, electrical burns, hand burns, and burns to the genitalia.

Airway management is a priority in burn injuries. Inhalation of hot particles can cause damage to the respiratory epithelium and lead to airway compromise. Signs of inhalation injury include visible burns or erythema to the face, soot around the nostrils and mouth, burnt/singed nasal hairs, hoarse voice, wheeze or stridor, swollen tissues in the mouth or nostrils, and tachypnea and tachycardia. Supplemental oxygen should be provided, and endotracheal intubation may be necessary if there is airway obstruction or impending obstruction.

The initial management of a patient with burn injuries involves conserving body heat, covering burns with clean or sterile coverings, establishing IV access, providing pain relief, initiating fluid resuscitation, measuring urinary output with a catheter, maintaining nil by mouth status, closely monitoring vital signs and urine output, monitoring the airway, preparing for surgery if necessary, and administering medications.

Burns can be classified based on the depth of injury, ranging from simple erythema to full thickness burns that penetrate into subcutaneous tissue. The extent of a burn can be estimated using methods such as the rule of nines or the Lund and Browder chart, which takes into account age-specific body proportions.

Fluid management is crucial in burn injuries due to significant fluid losses. Evaporative fluid loss from burnt skin and increased permeability of blood vessels can lead to reduced intravascular volume and tissue perfusion. Fluid resuscitation should be aggressive in severe burns, while burns <15% in adults and <10% in children may not require immediate fluid resuscitation. The Parkland formula can be used to calculate the intravenous fluid requirements for someone with a significant burn injury.

During the third trimester of pregnancy, the use of selective serotonin reuptake inhibitors (SSRIs) has been associated with a discontinuation syndrome and persistent pulmonary hypertension of the newborn. It is important to be aware of the adverse effects of various drugs during pregnancy. For example, ACE inhibitors like ramipril, if given in the second and third trimester, can cause hypoperfusion, renal failure, and the oligohydramnios sequence. Aminoglycosides such as gentamicin can lead to ototoxicity and deafness. High doses of aspirin can result in first-trimester abortions, delayed onset labor, premature closure of the fetal ductus arteriosus, and fetal kernicterus. However, low doses (e.g., 75 mg) do not pose significant risks. Late administration of benzodiazepines like diazepam during pregnancy can cause respiratory depression and a neonatal withdrawal syndrome. Calcium-channel blockers, if given in the first trimester, may cause phalangeal abnormalities, while their use in the second and third trimester can lead to fetal growth retardation. Carbamazepine has been associated with hemorrhagic disease of the newborn and neural tube defects. Chloramphenicol can cause grey baby syndrome. Corticosteroids, if given in the first trimester, may cause orofacial clefts. Danazol, if administered in the first trimester, can result in masculinization of the female fetuses genitals. Pregnant women should avoid handling crushed or broken tablets of finasteride as it can be absorbed through the skin and affect male sex organ development. Haloperidol, if given in the first trimester, may cause limb malformations, while its use in the third trimester increases the risk of extrapyramidal symptoms in the neonate. Heparin can lead to maternal bleeding and thrombocytopenia. Isoniazid can cause maternal liver damage and neuropathy and seizures in the neonate. Isotretinoin carries a high risk of teratogenicity, including multiple congenital malformations, spontaneous abortion, and intellectual disability. The use of lithium in the first trimester increases the risk of fetal cardiac malformations, while its use in the second and third trimesters can result in hypotonia, lethargy, feeding problems, hypothyroidism, goiter, and nephrogenic diabetes insipidus.

The classification of severity in salicylate overdose can sometimes be confused by mixing up the ingested dose and the measured plasma salicylate level. To clarify, when using the blood salicylate level, moderate toxicity is indicated by a level of 350-700 mg/L, while severe toxicity is indicated by a level exceeding 700 mg/L.

Further Reading:

Salicylate poisoning, particularly from aspirin overdose, is a common cause of poisoning in the UK. One important concept to understand is that salicylate overdose leads to a combination of respiratory alkalosis and metabolic acidosis. Initially, the overdose stimulates the respiratory center, leading to hyperventilation and respiratory alkalosis. However, as the effects of salicylate on lactic acid production, breakdown into acidic metabolites, and acute renal injury occur, it can result in high anion gap metabolic acidosis.

The clinical features of salicylate poisoning include hyperventilation, tinnitus, lethargy, sweating, pyrexia (fever), nausea/vomiting, hyperglycemia and hypoglycemia, seizures, and coma.

When investigating salicylate poisoning, it is important to measure salicylate levels in the blood. The sample should be taken at least 2 hours after ingestion for symptomatic patients or 4 hours for asymptomatic patients. The measurement should be repeated every 2-3 hours until the levels start to decrease. Other investigations include arterial blood gas analysis, electrolyte levels (U&Es), complete blood count (FBC), coagulation studies (raised INR/PTR), urinary pH, and blood glucose levels.

To manage salicylate poisoning, an ABC approach should be followed to ensure a patent airway and adequate ventilation. Activated charcoal can be administered if the patient presents within 1 hour of ingestion. Oral or intravenous fluids should be given to optimize intravascular volume. Hypokalemia and hypoglycemia should be corrected. Urinary alkalinization with intravenous sodium bicarbonate can enhance the elimination of aspirin in the urine. In severe cases, hemodialysis may be necessary.

Urinary alkalinization involves targeting a urinary pH of 7.5-8.5 and checking it hourly. It is important to monitor for hypokalemia as alkalinization can cause potassium to shift from plasma into cells. Potassium levels should be checked every 1-2 hours.

In cases where the salicylate concentration is high (above 500 mg/L in adults or 350 mg/L in children), sodium bicarbonate can be administered intravenously. Hemodialysis is the treatment of choice for severe poisoning and may be indicated in cases of high salicylate levels, resistant metabolic acidosis, acute kidney injury, pulmonary edema, seizures and coma..

Activated charcoal is a commonly used substance for decontamination in cases of poisoning. Its main function is to adsorb the molecules of the ingested toxin onto its surface.

Activated charcoal is a chemically inert form of carbon. It is a fine black powder that has no odor or taste. It is produced by subjecting carbonaceous matter to high heat, a process known as pyrolysis, and then treating it with a zinc chloride solution to increase its concentration. This process creates a network of pores within the charcoal, giving it a large absorptive area of approximately 3,000 m2/g. This allows it to effectively inhibit the absorption of toxins by up to 50%.

The usual dose of activated charcoal is 50 grams for adults and 1 gram per kilogram of body weight for children. It can be administered orally or through a nasogastric tube. It is important to administer it within one hour of ingestion, and it may be repeated after one hour if necessary.

However, there are certain situations where activated charcoal should not be used. These include cases where the patient is unconscious or in a coma, as there is a risk of aspiration. It should also be avoided if seizures are imminent, as there is a risk of aspiration. Additionally, if there is reduced gastrointestinal motility, activated charcoal should not be used to prevent the risk of obstruction.

Activated charcoal is effective in treating overdose with certain drugs and toxins, such as aspirin, paracetamol, barbiturates, tricyclic antidepressants, digoxin, amphetamines, morphine, cocaine, and phenothiazines. However, it is ineffective in cases of overdose with iron, lithium, boric acid, cyanide, ethanol, ethylene glycol, methanol, malathion, DDT, carbamate, hydrocarbon, strong acids, or alkalis.

There are potential adverse effects associated with the use of activated charcoal. These include nausea and vomiting, diarrhea, constipation, bezoar formation (a mass of undigested material that can cause blockages), bowel obstruction, pulmonary aspiration (inhalation of charcoal into the lungs), and impaired absorption of oral medications or antidotes.

SIADH is a medical condition that is not brought on by lithium toxicity. However, lithium toxicity does have its own distinct set of symptoms. These symptoms include nausea and vomiting, diarrhea, tremors, ataxia, confusion, increased muscle tone, clonus, nephrogenic diabetes insipidus, convulsions, coma, and renal failure. It is important to note that SIADH and lithium toxicity are separate conditions with their own unique characteristics.

Salicylate poisoning is a fairly common form of poisoning that can lead to organ damage and death if not treated promptly. Some common symptoms include nausea, vomiting, ringing in the ears, hearing loss, excessive sweating, and dehydration. Additionally, individuals may experience rapid breathing, flushed skin, and high fever, particularly in children. In severe cases, convulsions, swelling of the brain, coma, kidney failure, fluid accumulation in the lungs unrelated to heart problems, and unstable cardiovascular function may occur.

Early on in the overdose, arterial blood gas analysis typically reveals a respiratory alkalosis due to overstimulation of the respiratory center. As the overdose progresses, especially in moderate to severe cases, a metabolic acidosis with an increased anion gap may develop as a result of elevated levels of protons in the blood.

Electrocardiogram (ECG) abnormalities that may be observed include widening of the QRS complex, atrioventricular (AV) block, and ventricular arrhythmias.

Paracetamol overdose is the most common overdose in the U.K. and is also the leading cause of acute liver failure. The liver damage occurs due to a metabolite of paracetamol called N-acetyl-p-benzoquinoneimine (NAPQI), which depletes the liver’s glutathione stores and directly harms liver cells. Severe liver damage and even death can result from an overdose of more than 12 g or > 150 mg/kg body weight.

The clinical manifestations of paracetamol overdose can be divided into four stages:

Stage 1 (0-24 hours): Patients may not show any symptoms, but common signs include nausea, vomiting, and abdominal discomfort.

Stage 2 (24-48 hours): Right upper quadrant pain and tenderness develop, along with the possibility of hypoglycemia and reduced consciousness.

Stage 3 (48-96 hours): Hepatic failure begins, characterized by jaundice, coagulopathy, and encephalopathy. Loin pain, haematuria, and proteinuria may indicate early renal failure.

Stage 4 (> 96 hours): Hepatic failure worsens progressively, leading to cerebral edema, disseminated intravascular coagulation (DIC), and ultimately death.

The earliest and most sensitive indicator of liver damage is a prolonged INR, which starts to rise approximately 24 hours after the overdose. Liver function tests (LFTs) typically remain normal until 18 hours after the overdose. However, AST and ALT levels then sharply increase and can exceed 10,000 units/L by 72-96 hours. Bilirubin levels rise more slowly and peak around 5 days.

The primary treatment for paracetamol overdose is acetylcysteine. Acetylcysteine is a highly effective antidote, but its efficacy diminishes rapidly if administered more than 8 hours after a significant ingestion. Ingestions exceeding 75 mg/kg are considered significant.

Acetylcysteine should be given based on a 4-hour level or administered empirically if the presentation occurs more than 8 hours after a significant overdose. If the overdose is staggered or the timing is uncertain, empirical treatment is also recommended. The treatment regimen is as follows:

– First dose: 150 mg/kg in 200 mL 5% glucose over 1 hour
– Second dose 50 mg/kg in 500 mL 5% glucose over 4 hours
– Third dose 100 mg/kg in 1000 mL 5% glucose over 16 hours

Theophylline is a medication used to treat severe asthma. It is a bronchodilator that comes in modified-release forms, which can maintain therapeutic levels in the blood for 12 hours. Theophylline works by inhibiting phosphodiesterase and blocking the breakdown of cyclic AMP. It also competes with adenosine on A1 and A2 receptors.

Achieving the right dose of theophylline can be challenging because there is a narrow range between therapeutic and toxic levels. The half-life of theophylline can be influenced by various factors, further complicating dosage adjustments. It is recommended to aim for serum levels of 10-20 mg/l six to eight hours after the last dose.

Unlike many other medications, the specific brand of theophylline can significantly impact its effects. Therefore, it is important to prescribe theophylline by both its brand name and generic name.

Several factors can increase the half-life of theophylline, including heart failure, cirrhosis, viral infections, and certain drugs. Conversely, smoking, heavy drinking, and certain medications can decrease the half-life of theophylline.

There are several drugs that can either increase or decrease the plasma concentration of theophylline. Calcium channel blockers, cimetidine, fluconazole, macrolides, methotrexate, and quinolones can increase the concentration. On the other hand, carbamazepine, phenobarbitol, phenytoin, rifampicin, and St. John’s wort can decrease the concentration.

The clinical symptoms of theophylline toxicity are more closely associated with acute overdose rather than chronic overexposure. Common symptoms include headache, dizziness, nausea, vomiting, abdominal pain, rapid heartbeat, dysrhythmias, seizures, mild metabolic acidosis, low potassium, low magnesium, low phosphates, abnormal calcium levels, and high blood sugar.

Seizures are more prevalent in acute overdose cases, while chronic overdose typically presents with minimal gastrointestinal symptoms. Cardiac dysrhythmias are more common in chronic overdose situations compared to acute overdose.

Corneal microdeposits are found in almost all individuals (over 90%) who have been taking amiodarone for more than six months, particularly at doses higher than 400 mg/day. These deposits generally do not cause any symptoms, although approximately 10% of patients may experience a perception of a ‘bluish halo’ around objects they see.

Amiodarone can also have other effects on the eye, but these are much less common, occurring in only 1-2% of patients. These effects include optic neuropathy, nonarteritic anterior ischemic optic neuropathy (N-AION), optic disc swelling, and visual field defects.

The primary treatment for malignant hyperthermia is dantrolene. Dantrolene works by blocking the release of calcium through calcium channels, resulting in the relaxation of skeletal muscles.

Further Reading:

Malignant hyperthermia is a rare and life-threatening syndrome that can be triggered by certain medications in individuals who are genetically susceptible. The most common triggers are suxamethonium and inhalational anaesthetic agents. The syndrome is caused by the release of stored calcium ions from skeletal muscle cells, leading to uncontrolled muscle contraction and excessive heat production. This results in symptoms such as high fever, sweating, flushed skin, rapid heartbeat, and muscle rigidity. It can also lead to complications such as acute kidney injury, rhabdomyolysis, and metabolic acidosis. Treatment involves discontinuing the trigger medication, administering dantrolene to inhibit calcium release and promote muscle relaxation, and managing any associated complications such as hyperkalemia and acidosis. Referral to a malignant hyperthermia center for further investigation is also recommended.

The patient is experiencing acidosis, as indicated by the low pH. The low bicarb and base excess levels suggest that the metabolic system is contributing to or causing the acidosis. Additionally, the low pCO2 indicates that the respiratory system is attempting to compensate by driving alkalosis. However, the metabolic system is the primary factor in this case, leading to a diagnosis of metabolic acidosis with incomplete respiratory compensation.

Further Reading:

Salicylate poisoning, particularly from aspirin overdose, is a common cause of poisoning in the UK. One important concept to understand is that salicylate overdose leads to a combination of respiratory alkalosis and metabolic acidosis. Initially, the overdose stimulates the respiratory center, leading to hyperventilation and respiratory alkalosis. However, as the effects of salicylate on lactic acid production, breakdown into acidic metabolites, and acute renal injury occur, it can result in high anion gap metabolic acidosis.

The clinical features of salicylate poisoning include hyperventilation, tinnitus, lethargy, sweating, pyrexia (fever), nausea/vomiting, hyperglycemia and hypoglycemia, seizures, and coma.

When investigating salicylate poisoning, it is important to measure salicylate levels in the blood. The sample should be taken at least 2 hours after ingestion for symptomatic patients or 4 hours for asymptomatic patients. The measurement should be repeated every 2-3 hours until the levels start to decrease. Other investigations include arterial blood gas analysis, electrolyte levels (U&Es), complete blood count (FBC), coagulation studies (raised INR/PTR), urinary pH, and blood glucose levels.

To manage salicylate poisoning, an ABC approach should be followed to ensure a patent airway and adequate ventilation. Activated charcoal can be administered if the patient presents within 1 hour of ingestion. Oral or intravenous fluids should be given to optimize intravascular volume. Hypokalemia and hypoglycemia should be corrected. Urinary alkalinization with intravenous sodium bicarbonate can enhance the elimination of aspirin in the urine. In severe cases, hemodialysis may be necessary.

Urinary alkalinization involves targeting a urinary pH of 7.5-8.5 and checking it hourly. It is important to monitor for hypokalemia as alkalinization can cause potassium to shift from plasma into cells. Potassium levels should be checked every 1-2 hours.

In cases where the salicylate concentration is high (above 500 mg/L in adults or 350 mg/L in children), sodium bicarbonate can be administered intravenously. Hemodialysis is the treatment of choice for severe poisoning and may be indicated in cases of high salicylate levels, resistant metabolic acidosis, acute kidney injury, pulmonary edema, seizures and coma.

Non-selective beta-blockers, like propranolol, can cause severe bronchospasm in individuals with asthma, particularly when taken in high doses. The current guidelines from the British Thoracic Society (BTS) recommend avoiding the use of beta-blockers in asthma patients. However, there is some evidence suggesting that the long-term use of cardioselective beta-blockers does not appear to trigger asthma attacks in individuals with mild or moderate asthma.

Beta-blockers play a crucial role in the treatment of patients who have a history of previous myocardial infarction or systolic dysfunction. In individuals with asthma and one of these diagnoses, it is unlikely that the potential benefits of beta-blockers outweigh the risks of worsening asthma symptoms.

Patients who have taken an overdose of tricyclic antidepressants (TCAs) should not be given phenytoin.

Further Reading:

Tricyclic antidepressant (TCA) overdose is a common occurrence in emergency departments, with drugs like amitriptyline and dosulepin being particularly dangerous. TCAs work by inhibiting the reuptake of norepinephrine and serotonin in the central nervous system. In cases of toxicity, TCAs block various receptors, including alpha-adrenergic, histaminic, muscarinic, and serotonin receptors. This can lead to symptoms such as hypotension, altered mental state, signs of anticholinergic toxicity, and serotonin receptor effects.

TCAs primarily cause cardiac toxicity by blocking sodium and potassium channels. This can result in a slowing of the action potential, prolongation of the QRS complex, and bradycardia. However, the blockade of muscarinic receptors also leads to tachycardia in TCA overdose. QT prolongation and Torsades de Pointes can occur due to potassium channel blockade. TCAs can also have a toxic effect on the myocardium, causing decreased cardiac contractility and hypotension.

Early symptoms of TCA overdose are related to their anticholinergic properties and may include dry mouth, pyrexia, dilated pupils, agitation, sinus tachycardia, blurred vision, flushed skin, tremor, and confusion. Severe poisoning can lead to arrhythmias, seizures, metabolic acidosis, and coma. ECG changes commonly seen in TCA overdose include sinus tachycardia, widening of the QRS complex, prolongation of the QT interval, and an R/S ratio >0.7 in lead aVR.

Management of TCA overdose involves ensuring a patent airway, administering activated charcoal if ingestion occurred within 1 hour and the airway is intact, and considering gastric lavage for life-threatening cases within 1 hour of ingestion. Serial ECGs and blood gas analysis are important for monitoring. Intravenous fluids and correction of hypoxia are the first-line therapies. IV sodium bicarbonate is used to treat haemodynamic instability caused by TCA overdose, and benzodiazepines are the treatment of choice for seizure control. Other treatments that may be considered include glucagon, magnesium sulfate, and intravenous lipid emulsion.

There are certain things to avoid in TCA overdose, such as anti-arrhythmics like quinidine and flecainide, as they can prolonged depolarization.

This patient has presented with symptoms and signs consistent with myopathy. Myopathy is characterized by muscle weakness, muscle atrophy, and reduced tone and reflexes. Hyperkalemia is a known biochemical cause for myopathy, while other metabolic causes include hypokalemia, hypercalcemia, hypomagnesemia, hyperthyroidism, hypothyroidism, diabetes mellitus, Cushing’s disease, and Conn’s syndrome. In this case, ACE inhibitors, such as ramipril, are a well-recognized cause of hyperkalemia and are likely responsible.

Commonly encountered side effects of ACE inhibitors include renal impairment, persistent dry cough, angioedema (with delayed onset), rashes, upper respiratory tract symptoms (such as a sore throat), and gastrointestinal upset.

Common side effects of bendroflumethiazide include postural hypotension, electrolyte disturbance (such as hypokalaemia, hyponatraemia, and hypercalcaemia), impaired glucose tolerance, gout, impotence, and fatigue. Rare side effects of bendroflumethiazide include thrombocytopenia, agranulocytosis, photosensitive rash, pancreatitis, and renal failure.

Activated charcoal is a commonly utilized substance for decontamination in cases of poisoning. Its main function is to attract and bind molecules of the ingested toxin onto its surface.

Activated charcoal is a chemically inert form of carbon. It is a fine black powder that has no odor or taste. This powder is created by subjecting carbonaceous matter to high heat, a process known as pyrolysis, and then concentrating it with a solution of zinc chloride. Through this process, the activated charcoal develops a complex network of pores, providing it with a large surface area of approximately 3,000 m2/g. This extensive surface area allows it to effectively hinder the absorption of the harmful toxin by up to 50%.

The typical dosage for adults is 50 grams, while children are usually given 1 gram per kilogram of body weight. Activated charcoal can be administered orally or through a nasogastric tube. It is crucial to administer it within one hour of ingestion, and if necessary, a second dose may be repeated after one hour.

Sodium bicarbonate is recommended as a treatment for TCA overdose according to the latest guidelines from RCEM and NPIS in 2021. Previous editions also suggested using glucagon if IV fluids and sodium bicarbonate were ineffective in treating the overdose.

Further Reading:

Tricyclic antidepressant (TCA) overdose is a common occurrence in emergency departments, with drugs like amitriptyline and dosulepin being particularly dangerous. TCAs work by inhibiting the reuptake of norepinephrine and serotonin in the central nervous system. In cases of toxicity, TCAs block various receptors, including alpha-adrenergic, histaminic, muscarinic, and serotonin receptors. This can lead to symptoms such as hypotension, altered mental state, signs of anticholinergic toxicity, and serotonin receptor effects.

TCAs primarily cause cardiac toxicity by blocking sodium and potassium channels. This can result in a slowing of the action potential, prolongation of the QRS complex, and bradycardia. However, the blockade of muscarinic receptors also leads to tachycardia in TCA overdose. QT prolongation and Torsades de Pointes can occur due to potassium channel blockade. TCAs can also have a toxic effect on the myocardium, causing decreased cardiac contractility and hypotension.

Early symptoms of TCA overdose are related to their anticholinergic properties and may include dry mouth, pyrexia, dilated pupils, agitation, sinus tachycardia, blurred vision, flushed skin, tremor, and confusion. Severe poisoning can lead to arrhythmias, seizures, metabolic acidosis, and coma. ECG changes commonly seen in TCA overdose include sinus tachycardia, widening of the QRS complex, prolongation of the QT interval, and an R/S ratio >0.7 in lead aVR.

Management of TCA overdose involves ensuring a patent airway, administering activated charcoal if ingestion occurred within 1 hour and the airway is intact, and considering gastric lavage for life-threatening cases within 1 hour of ingestion. Serial ECGs and blood gas analysis are important for monitoring. Intravenous fluids and correction of hypoxia are the first-line therapies. IV sodium bicarbonate is used to treat haemodynamic instability caused by TCA overdose, and benzodiazepines are the treatment of choice for seizure control. Other treatments that may be considered include glucagon, magnesium sulfate, and intravenous lipid emulsion.

There are certain things to avoid in TCA overdose, such as anti-arrhythmics like quinidine and flecainide, as they can prolonged depolarization.

Theophylline is a medication used to treat severe asthma. It is a bronchodilator that comes in modified-release forms, which can maintain therapeutic levels in the blood for 12 hours. Theophylline works by inhibiting phosphodiesterase and blocking the breakdown of cyclic AMP. It also competes with adenosine on A1 and A2 receptors.

Achieving the right dose of theophylline can be challenging because there is a narrow range between therapeutic and toxic levels. The half-life of theophylline can be influenced by various factors, further complicating dosage adjustments. It is recommended to aim for serum levels of 10-20 mg/l six to eight hours after the last dose.

Unlike many other medications, the specific brand of theophylline can significantly impact its effects. Therefore, it is important to prescribe theophylline by both its brand name and generic name.

Several factors can increase the half-life of theophylline, including heart failure, cirrhosis, viral infections, and certain drugs. Conversely, smoking, heavy drinking, and certain medications can decrease the half-life of theophylline.

There are several drugs that can either increase or decrease the plasma concentration of theophylline. Calcium channel blockers, cimetidine, fluconazole, macrolides, methotrexate, and quinolones can increase the concentration. On the other hand, carbamazepine, phenobarbitol, phenytoin, rifampicin, and St. John’s wort can decrease the concentration.

The clinical symptoms of theophylline toxicity are more closely associated with acute overdose rather than chronic overexposure. Common symptoms include headache, dizziness, nausea, vomiting, abdominal pain, rapid heartbeat, dysrhythmias, seizures, mild metabolic acidosis, low potassium, low magnesium, low phosphates, abnormal calcium levels, and high blood sugar.

Seizures are more prevalent in acute overdose cases, while chronic overdose typically presents with minimal gastrointestinal symptoms. Cardiac dysrhythmias are more common in chronic overdose situations compared to acute overdose.

When it comes to managing seizures in cases of TCA overdose, benzodiazepines are considered the most effective treatment. Diazepam or lorazepam are commonly administered for this purpose. However, it’s important to note that lamotrigine and carbamazepine are typically used for preventing seizures rather than for immediate seizure control.

Further Reading:

Tricyclic antidepressant (TCA) overdose is a common occurrence in emergency departments, with drugs like amitriptyline and dosulepin being particularly dangerous. TCAs work by inhibiting the reuptake of norepinephrine and serotonin in the central nervous system. In cases of toxicity, TCAs block various receptors, including alpha-adrenergic, histaminic, muscarinic, and serotonin receptors. This can lead to symptoms such as hypotension, altered mental state, signs of anticholinergic toxicity, and serotonin receptor effects.

TCAs primarily cause cardiac toxicity by blocking sodium and potassium channels. This can result in a slowing of the action potential, prolongation of the QRS complex, and bradycardia. However, the blockade of muscarinic receptors also leads to tachycardia in TCA overdose. QT prolongation and Torsades de Pointes can occur due to potassium channel blockade. TCAs can also have a toxic effect on the myocardium, causing decreased cardiac contractility and hypotension.

Early symptoms of TCA overdose are related to their anticholinergic properties and may include dry mouth, pyrexia, dilated pupils, agitation, sinus tachycardia, blurred vision, flushed skin, tremor, and confusion. Severe poisoning can lead to arrhythmias, seizures, metabolic acidosis, and coma. ECG changes commonly seen in TCA overdose include sinus tachycardia, widening of the QRS complex, prolongation of the QT interval, and an R/S ratio >0.7 in lead aVR.

Management of TCA overdose involves ensuring a patent airway, administering activated charcoal if ingestion occurred within 1 hour and the airway is intact, and considering gastric lavage for life-threatening cases within 1 hour of ingestion. Serial ECGs and blood gas analysis are important for monitoring. Intravenous fluids and correction of hypoxia are the first-line therapies. IV sodium bicarbonate is used to treat haemodynamic instability caused by TCA overdose, and benzodiazepines are the treatment of choice for seizure control. Other treatments that may be considered include glucagon, magnesium sulfate, and intravenous lipid emulsion.

There are certain things to avoid in TCA overdose, such as anti-arrhythmics like quinidine and flecainide, as they can prolonged depolarization.

TCA toxicity can be identified through specific changes seen on an electrocardiogram (ECG). Sinus tachycardia, which is a faster than normal heart rate, and widening of the QRS complex are key features of TCA toxicity. These ECG changes occur due to the blocking of sodium channels and muscarinic receptors (M1) by the medication. In the case of an amitriptyline overdose, additional ECG changes may include prolongation of the QT interval, an R/S ratio greater than 0.7 in lead aVR, and the presence of ventricular arrhythmias such as torsades de pointes. The severity of the QRS prolongation on the ECG is associated with the likelihood of adverse events. A QRS duration greater than 100 ms is predictive of seizures, while a QRS duration greater than 160 ms is predictive of ventricular arrhythmias like ventricular tachycardia or torsades de pointes.

Further Reading:

Tricyclic antidepressant (TCA) overdose is a common occurrence in emergency departments, with drugs like amitriptyline and dosulepin being particularly dangerous. TCAs work by inhibiting the reuptake of norepinephrine and serotonin in the central nervous system. In cases of toxicity, TCAs block various receptors, including alpha-adrenergic, histaminic, muscarinic, and serotonin receptors. This can lead to symptoms such as hypotension, altered mental state, signs of anticholinergic toxicity, and serotonin receptor effects.

TCAs primarily cause cardiac toxicity by blocking sodium and potassium channels. This can result in a slowing of the action potential, prolongation of the QRS complex, and bradycardia. However, the blockade of muscarinic receptors also leads to tachycardia in TCA overdose. QT prolongation and Torsades de Pointes can occur due to potassium channel blockade. TCAs can also have a toxic effect on the myocardium, causing decreased cardiac contractility and hypotension.

Early symptoms of TCA overdose are related to their anticholinergic properties and may include dry mouth, pyrexia, dilated pupils, agitation, sinus tachycardia, blurred vision, flushed skin, tremor, and confusion. Severe poisoning can lead to arrhythmias, seizures, metabolic acidosis, and coma. ECG changes commonly seen in TCA overdose include sinus tachycardia, widening of the QRS complex, prolongation of the QT interval, and an R/S ratio >0.7 in lead aVR.

Management of TCA overdose involves ensuring a patent airway, administering activated charcoal if ingestion occurred within 1 hour and the airway is intact, and considering gastric lavage for life-threatening cases within 1 hour of ingestion. Serial ECGs and blood gas analysis are important for monitoring. Intravenous fluids and correction of hypoxia are the first-line therapies. IV sodium bicarbonate is used to treat haemodynamic instability caused by TCA overdose, and benzodiazepines are the treatment of choice for seizure control. Other treatments that may be considered include glucagon, magnesium sulfate, and intravenous lipid emulsion.

There are certain things to avoid in TCA overdose, such as anti-arrhythmics like quinidine and flecainide, as they can prolonged depolarization. Amiodarone should

Haemodialysis is recommended for patients with salicylate poisoning if they meet any of the following criteria: plasma salicylate level exceeding 700 mg/L, metabolic acidosis that does not improve with treatment (plasma pH below 7.2), acute kidney injury, pulmonary edema, seizures, coma, unresolved central nervous system effects despite correcting acidosis, persistently high salicylate concentrations that do not respond to urinary alkalinisation. Severe cases of salicylate poisoning, especially in patients under 10 years old or over 70 years old, may require dialysis earlier than the listed indications.

Further Reading:

Salicylate poisoning, particularly from aspirin overdose, is a common cause of poisoning in the UK. One important concept to understand is that salicylate overdose leads to a combination of respiratory alkalosis and metabolic acidosis. Initially, the overdose stimulates the respiratory center, leading to hyperventilation and respiratory alkalosis. However, as the effects of salicylate on lactic acid production, breakdown into acidic metabolites, and acute renal injury occur, it can result in high anion gap metabolic acidosis.

The clinical features of salicylate poisoning include hyperventilation, tinnitus, lethargy, sweating, pyrexia (fever), nausea/vomiting, hyperglycemia and hypoglycemia, seizures, and coma.

When investigating salicylate poisoning, it is important to measure salicylate levels in the blood. The sample should be taken at least 2 hours after ingestion for symptomatic patients or 4 hours for asymptomatic patients. The measurement should be repeated every 2-3 hours until the levels start to decrease. Other investigations include arterial blood gas analysis, electrolyte levels (U&Es), complete blood count (FBC), coagulation studies (raised INR/PTR), urinary pH, and blood glucose levels.

To manage salicylate poisoning, an ABC approach should be followed to ensure a patent airway and adequate ventilation. Activated charcoal can be administered if the patient presents within 1 hour of ingestion. Oral or intravenous fluids should be given to optimize intravascular volume. Hypokalemia and hypoglycemia should be corrected. Urinary alkalinization with intravenous sodium bicarbonate can enhance the elimination of aspirin in the urine. In severe cases, hemodialysis may be necessary.

Urinary alkalinization involves targeting a urinary pH of 7.5-8.5 and checking it hourly. It is important to monitor for hypokalemia as alkalinization can cause potassium to shift from plasma into cells. Potassium levels should be checked every 1-2 hours.

In cases where the salicylate concentration is high (above 500 mg/L in adults or 350 mg/L in children), sodium bicarbonate can be administered intravenously. Hemodialysis is the treatment of choice for severe poisoning and may be indicated in cases of high salicylate levels, resistant metabolic acidosis, acute kidney injury, pulmonary edema, seizures and coma.

If IV methylene blue is obtained, it is typically used to treat a specific cause. However, if there is no response to methylene blue, alternative treatments such as hyperbaric oxygen or exchange transfusion may be considered. In cases where the cause is NADH-methaemoglobinaemia reductase deficiency, ascorbic acid can be used as a potential treatment.

Further Reading:

Methaemoglobinaemia is a condition where haemoglobin is oxidised from Fe2+ to Fe3+. This process is normally regulated by NADH methaemoglobin reductase, which transfers electrons from NADH to methaemoglobin, converting it back to haemoglobin. In healthy individuals, methaemoglobin levels are typically less than 1% of total haemoglobin. However, an increase in methaemoglobin can lead to tissue hypoxia as Fe3+ cannot bind oxygen effectively.

Methaemoglobinaemia can be congenital or acquired. Congenital causes include haemoglobin chain variants (HbM, HbH) and NADH methaemoglobin reductase deficiency. Acquired causes can be due to exposure to certain drugs or chemicals, such as sulphonamides, local anaesthetics (especially prilocaine), nitrates, chloroquine, dapsone, primaquine, and phenytoin. Aniline dyes are also known to cause methaemoglobinaemia.

Clinical features of methaemoglobinaemia include slate grey cyanosis (blue to grey skin coloration), chocolate blood or chocolate cyanosis (brown color of blood), dyspnoea, low SpO2 on pulse oximetry (which often does not improve with supplemental oxygen), and normal PaO2 on arterial blood gas (ABG) but low SaO2. Patients may tolerate hypoxia better than expected. Severe cases can present with acidosis, arrhythmias, seizures, and coma.

Diagnosis of methaemoglobinaemia is made by directly measuring the level of methaemoglobin using a co-oximeter, which is present in most modern blood gas analysers. Other investigations, such as a full blood count (FBC), electrocardiogram (ECG), chest X-ray (CXR), and beta-human chorionic gonadotropin (bHCG) levels (in pregnancy), may be done to assess the extent of the condition and rule out other contributing factors.

Active treatment is required if the methaemoglobin level is above 30% or if it is below 30% but the patient is symptomatic or shows evidence of tissue hypoxia. Treatment involves maintaining the airway and delivering high-flow oxygen, removing the causative agents, treating toxidromes and consider giving IV dextrose 5%.

The cardiotoxic effects of TCAs occur when they block sodium channels, leading to broadening of the QRS complex, and potassium channels, resulting in prolongation of the QT interval. The severity of adverse events is directly related to the degree of QRS broadening. If the QRS complex is greater than 100 ms, it is likely that seizures may occur. If the QRS complex exceeds 160 ms, ventricular arrhythmias may be predicted. In cases of TCA overdose, certain changes can be observed on an ECG. These include sinus tachycardia, which is very common, prolongation of the PR interval, broadening of the QRS complex, prolongation of the QT interval, and in severe cases, ventricular arrhythmias.

The most suitable dosage of epinephrine for a patient experiencing anaphylaxis after a flu vaccination is 500 micrograms (0.5ml 1 in 1,000) adrenaline by intramuscular injection.

Anaphylaxis is a severe and life-threatening hypersensitivity reaction that can have sudden onset and progression. It is characterized by skin or mucosal changes and can lead to life-threatening airway, breathing, or circulatory problems. Anaphylaxis can be allergic or non-allergic in nature.

In allergic anaphylaxis, there is an immediate hypersensitivity reaction where an antigen stimulates the production of IgE antibodies. These antibodies bind to mast cells and basophils. Upon re-exposure to the antigen, the IgE-covered cells release histamine and other inflammatory mediators, causing smooth muscle contraction and vasodilation.

Non-allergic anaphylaxis occurs when mast cells degrade due to a non-immune mediator. The clinical outcome is the same as in allergic anaphylaxis.

The management of anaphylaxis is the same regardless of the cause. Adrenaline is the most important drug and should be administered as soon as possible. The recommended doses for adrenaline vary based on age. Other treatments include high flow oxygen and an IV fluid challenge. Corticosteroids and chlorpheniramine are no longer recommended, while non-sedating antihistamines may be considered as third-line treatment after initial stabilization of airway, breathing, and circulation.

Common causes of anaphylaxis include food (such as nuts, which is the most common cause in children), drugs, and venom (such as wasp stings). Sometimes it can be challenging to determine if a patient had a true episode of anaphylaxis. In such cases, serum tryptase levels may be measured, as they remain elevated for up to 12 hours following an acute episode of anaphylaxis.

The Resuscitation Council (UK) provides guidelines for the management of anaphylaxis, including a visual algorithm that outlines the recommended steps for treatment.
https://www.resus.org.uk/sites/default/files/2021-05/Emergency%20Treatment%20of%20Anaphylaxis%20May%202021_0.pdf

The most commonly observed change in the electrocardiogram (ECG) during a tricyclic antidepressant (TCA) overdose is sinus tachycardia. Additionally, other ECG changes that can be seen in TCA overdose include prolongation of the PR interval, broadening of the QRS complex, prolongation of the QT interval, and the occurrence of ventricular arrhythmias in cases of severe toxicity. The cardiotoxic effects of TCAs are caused by the blocking of sodium channels, which leads to broadening of the QRS complex, and the blocking of potassium channels, which results in prolongation of the QT interval. The severity of the QRS broadening is associated with adverse events: a QRS duration greater than 100 ms is predictive of seizures, while a QRS duration greater than 160 ms is predictive of ventricular arrhythmias.

Flumazenil is a specific antagonist for benzodiazepines that can be beneficial in certain situations. It acts quickly, taking less than 1 minute to take effect, but its effects are short-lived and only last for less than 1 hour. The recommended dosage is 200 μg every 1-2 minutes, with a maximum dose of 3mg per hour.

It is important to avoid using Flumazenil if the patient is dependent on benzodiazepines or is taking tricyclic antidepressants. This is because it can trigger a withdrawal syndrome in these individuals, potentially leading to seizures or cardiac arrest.

Arterial blood gas (ABG) interpretation is essential for evaluating a patient’s respiratory gas exchange and acid-base balance. The normal values on an ABG may slightly vary between analyzers, but generally, they fall within the following ranges:

pH: 7.35 – 7.45
pO2: 10 – 14 kPa
PCO2: 4.5 – 6 kPa
HCO3-: 22 – 26 mmol/l
Base excess: -2 – 2 mmol/l

In this particular case, the patient’s history indicates an overdose. However, there is no immediate need for intubation as her Glasgow Coma Scale (GCS) score is 11/15, and she can speak, albeit with slurred speech, indicating that she can maintain her own airway.

The relevant ABG findings are as follows:

– Mild hypoxia
– Decreased pH (acidaemia)
– Low PCO2
– Normal bicarbonate
– Elevated lactate

The anion gap is a measure of the concentration of unmeasured anions in the plasma. It is calculated by subtracting the primary measured cations from the primary measured anions in the serum. The reference range for anion gap varies depending on the methodology used, but it is typically between 8 to 16 mmol/L.

In this case, the patient’s anion gap can be calculated using the formula:

Anion gap = [Na+] – [Cl-] – [HCO3-]

Using the given values:

Anion gap = [143] – [99] – [22]
Anion gap = 22

Therefore, it is evident that she has a raised anion gap metabolic acidosis. It is likely a type A lactic acidosis resulting from tissue hypoxia and hypoperfusion. Some potential causes of type A and type B lactic acidosis include:

Type A lactic acidosis:
– Shock (including septic shock)
– Left ventricular failure
– Severe anemia
– Asphyxia
– Cardiac arrest
– Carbon monoxide poisoning
– Respiratory failure
– Severe asthma and COPD
– Regional hypoperfusion

Type B lactic acidosis:
– Renal failure
– Liver failure
– Sepsis (non-hypoxic sepsis)
– Thiamine deficiency
– Al

Amlodipine is a medication that belongs to the class of calcium-channel blockers and is often prescribed for the management of high blood pressure. One of the most frequently observed side effects of calcium-channel blockers is the swelling of the ankles. Additionally, individuals taking these medications may also experience other common side effects such as nausea, flushing, dizziness, sleep disturbances, headaches, fatigue, abdominal pain, and palpitations.

The clinical manifestations of theophylline toxicity are more closely associated with acute poisoning rather than chronic overexposure. The primary clinical features of theophylline toxicity include headache, dizziness, nausea and vomiting, abdominal pain, tachycardia and dysrhythmias, seizures, mild metabolic acidosis, hypokalaemia, hypomagnesaemia, hypophosphataemia, hypo- or hypercalcaemia, and hyperglycaemia. Seizures are more prevalent in cases of acute overdose compared to chronic overexposure. In contrast, chronic theophylline overdose typically presents with minimal gastrointestinal symptoms. Cardiac dysrhythmias are more frequently observed in individuals who have experienced chronic overdose rather than acute overdose.