The nerve agents, also known as nerve gases, are a group of highly toxic chemical warfare agents that were initially developed just before and during World War II.

The first compounds to be created are called the G agents (G stands for German, as they were discovered and synthesized by German scientists). These include Tabun (GA), Sarin (GB), and Soman (GD).

In the 1950s, the V agents (V stands for venomous) were synthesized and are approximately 10 times more poisonous than sarin. These include Venomous agent X (VX), Venomous agent E (VE), Venomous agent G (VG), and Venomous agent M (VM).

One of the most well-known incidents involving the use of a nerve agent was the March 1995 Tokyo subway sarin attack. During this attack, Sarin was released into the Tokyo subway system during rush hour. As a result, over 5,000 people sought medical attention. Among them, 984 were moderately poisoned, 54 were severely poisoned, and 12 died.

Nerve agents are organophosphorus esters that are chemically related to organophosphorus insecticides. They work by inhibiting acetylcholinesterase (AChE), an enzyme that breaks down the neurotransmitter acetylcholine (ACh). This leads to an accumulation of ACh at both muscarinic and nicotinic cholinergic receptors.

Nerve agents can be absorbed through any body surface. When dispersed as a spray or aerosol, they can be absorbed through the skin, eyes, and respiratory tract. When dispersed as a vapor, they are primarily absorbed through the respiratory tract and eyes. If a sufficient amount of agent is absorbed, local effects are followed by generalized systemic effects.

The clinical features observed after exposure are a result of a combination of muscarinic, nicotinic, and central nervous system effects.

Muscarinic effects (DUMBBELS):
– Diarrhea
– Urination
– Miosis
– Bronchorrhea
– Bronchospasm
– Emesis
– Lacrimation
– Salivation
Plus bradycardia and hypotension.

Nicotinic effects:
– Sweating
– Tremor
– Fasciculations
– Muscle weakness
– Flaccid paralysis

Central nervous system effects:
– Agitation and irritability
– Amnesia
– Ataxia
– Respiratory

Diagnosing spontaneous bacterial peritonitis (SBP) requires an abdominal paracentesis of ascitic tap. Other reasons for performing a diagnostic tap include determining the cause of ascites, distinguishing between transudate and exudate, and detecting cancerous cells. Additionally, a therapeutic paracentesis can be done to alleviate respiratory distress or abdominal pain caused by the ascites.

However, there are certain contraindications to consider. These include having an uncooperative patient, a skin infection at the proposed puncture site, being pregnant, or experiencing severe bowel distension. Relative contraindications involve having severe thrombocytopenia (platelet count less than 20 x 103/μL) or coagulopathy (INR greater than 2.0).

For patients with an INR greater than 2.0, it is recommended to administer fresh frozen plasma (FFP) before the procedure. One approach is to infuse one unit of fresh frozen plasma prior to the procedure and then proceed with the paracentesis while the second unit is being infused.

In the case of patients with a platelet count lower than 20 x 103/μL, it is advisable to provide a platelet infusion before the procedure.

The count of lymphocytes, a type of white blood cell, can serve as an early indication of the level of radiation exposure. The severity of the exposure can be determined by observing the decrease in lymphocyte count, which is directly related to the amount of radiation absorbed by the body. Ideally, the count is measured 12 hours after exposure and then repeated every 4 hours initially to track the rate of decrease.

Further Reading:

Radiation exposure refers to the emission or transmission of energy in the form of waves or particles through space or a material medium. There are two types of radiation: ionizing and non-ionizing. Non-ionizing radiation, such as radio waves and visible light, has enough energy to move atoms within a molecule but not enough to remove electrons from atoms. Ionizing radiation, on the other hand, has enough energy to ionize atoms or molecules by detaching electrons from them.

There are different types of ionizing radiation, including alpha particles, beta particles, gamma rays, and X-rays. Alpha particles are positively charged and consist of 2 protons and 2 neutrons from the atom’s nucleus. They are emitted from the decay of heavy radioactive elements and do not travel far from the source atom. Beta particles are small, fast-moving particles with a negative electrical charge that are emitted from an atom’s nucleus during radioactive decay. They are more penetrating than alpha particles but less damaging to living tissue. Gamma rays and X-rays are weightless packets of energy called photons. Gamma rays are often emitted along with alpha or beta particles during radioactive decay and can easily penetrate barriers. X-rays, on the other hand, are generally lower in energy and less penetrating than gamma rays.

Exposure to ionizing radiation can damage tissue cells by dislodging orbital electrons, leading to the generation of highly reactive ion pairs. This can result in DNA damage and an increased risk of future malignant change. The extent of cell damage depends on factors such as the type of radiation, time duration of exposure, distance from the source, and extent of shielding.

The absorbed dose of radiation is directly proportional to time, so it is important to minimize the amount of time spent in the vicinity of a radioactive source. A lethal dose of radiation without medical management is 4.5 sieverts (Sv) to kill 50% of the population at 60 days. With medical management, the lethal dose is 5-6 Sv. The immediate effects of ionizing radiation can range from radiation burns to radiation sickness, which is divided into three main syndromes: hematopoietic, gastrointestinal, and neurovascular. Long-term effects can include hematopoietic cancers and solid tumor formation.

In terms of management, support is mainly supportive and includes IV fluids, antiemetics, analgesia, nutritional support, antibiotics, blood component substitution, and reduction of brain edema.

Most nosebleeds, also known as epistaxis, occur at a specific area called Little’s area.

Epistaxis, or nosebleed, is a common condition that can occur in both children and older adults. It is classified as either anterior or posterior, depending on the location of the bleeding. Anterior epistaxis usually occurs in younger individuals and arises from the nostril, most commonly from an area called Little’s area. These bleeds are usually not severe and account for the majority of nosebleeds seen in hospitals. Posterior nosebleeds, on the other hand, occur in older patients with conditions such as hypertension and atherosclerosis. The bleeding in posterior nosebleeds is likely to come from both nostrils and originates from the superior or posterior parts of the nasal cavity or nasopharynx.

The management of epistaxis involves assessing the patient for signs of instability and implementing measures to control the bleeding. Initial measures include sitting the patient upright with their upper body tilted forward and their mouth open. Firmly pinching the cartilaginous part of the nose for 10-15 minutes without releasing the pressure can also help stop the bleeding. If these measures are successful, a cream called Naseptin or mupirocin nasal ointment can be prescribed for further treatment.

If bleeding persists after the initial measures, nasal cautery or nasal packing may be necessary. Nasal cautery involves using a silver nitrate stick to cauterize the bleeding point, while nasal packing involves inserting nasal tampons or inflatable nasal packs to stop the bleeding. In cases of posterior bleeding, posterior nasal packing or surgery to tie off the bleeding vessel may be considered.

Complications of epistaxis can include nasal bleeding, hypovolemia, anemia, aspiration, and even death. Complications specific to nasal packing include sinusitis, septal hematoma or abscess, pressure necrosis, toxic shock syndrome, and apneic episodes. Nasal cautery can lead to complications such as septal perforation and caustic injury to the surrounding skin.

In children under the age of 2 presenting with epistaxis, it is important to refer them for further investigation as an underlying cause is more likely in this age group.

Before performing arterial blood gas sampling, it is necessary to disinfect the skin. This is typically done using alcohol, which should be applied and given enough time to dry completely before proceeding with the skin puncture. In the UK, it is common to use solutions that combine alcohol with Chlorhexidine, such as Chloraprep® (2).

Further Reading:

Arterial blood gases (ABG) are an important diagnostic tool used to assess a patient’s acid-base status and respiratory function. When obtaining an ABG sample, it is crucial to prioritize safety measures to minimize the risk of infection and harm to the patient. This includes performing hand hygiene before and after the procedure, wearing gloves and protective equipment, disinfecting the puncture site with alcohol, using safety needles when available, and properly disposing of equipment in sharps bins and contaminated waste bins.

To reduce the risk of harm to the patient, it is important to test for collateral circulation using the modified Allen test for radial artery puncture. Additionally, it is essential to inquire about any occlusive vascular conditions or anticoagulation therapy that may affect the procedure. The puncture site should be checked for signs of infection, injury, or previous surgery. After the test, pressure should be applied to the puncture site or the patient should be advised to apply pressure for at least 5 minutes to prevent bleeding.

Interpreting ABG results requires a systematic approach. The core set of results obtained from a blood gas analyser includes the partial pressures of oxygen and carbon dioxide, pH, bicarbonate concentration, and base excess. These values are used to assess the patient’s acid-base status.

The pH value indicates whether the patient is in acidosis, alkalosis, or within the normal range. A pH less than 7.35 indicates acidosis, while a pH greater than 7.45 indicates alkalosis.

The respiratory system is assessed by looking at the partial pressure of carbon dioxide (pCO2). An elevated pCO2 contributes to acidosis, while a low pCO2 contributes to alkalosis.

The metabolic aspect is assessed by looking at the bicarbonate (HCO3-) level and the base excess. A high bicarbonate concentration and base excess indicate alkalosis, while a low bicarbonate concentration and base excess indicate acidosis.

Analyzing the pCO2 and base excess values can help determine the primary disturbance and whether compensation is occurring. For example, a respiratory acidosis (elevated pCO2) may be accompanied by metabolic alkalosis (elevated base excess) as a compensatory response.

The anion gap is another important parameter that can help determine the cause of acidosis. It is calculated by subtracting the sum of chloride and bicarbonate from the sum of sodium and potassium.

The first step in managing acute mastoiditis is to administer broad spectrum intravenous antibiotics. The British Society of Otology recommends using intravenous ceftriaxone once daily in combination with intravenous metronidazole three times daily as the initial treatment. However, the specific antibiotic regimen may vary depending on the local antimicrobial policy.

Further Reading:

Mastoiditis is an infection of the mastoid air cells, which are located in the mastoid process of the skull. It is usually caused by the spread of infection from the middle ear. The most common organism responsible for mastoiditis is Streptococcus pneumoniae, but other bacteria and fungi can also be involved. The infection can spread to surrounding structures, such as the meninges, causing serious complications like meningitis or cerebral abscess.

Mastoiditis can be classified as acute or chronic. Acute mastoiditis is a rare complication of acute otitis media, which is inflammation of the middle ear. It is characterized by severe ear pain, fever, swelling and redness behind the ear, and conductive deafness. Chronic mastoiditis is usually associated with chronic suppurative otitis media or cholesteatoma and presents with recurrent episodes of ear pain, headache, and fever.

Mastoiditis is more common in children, particularly those between 6 and 13 months of age. Other risk factors include immunocompromised patients, those with intellectual impairment or communication difficulties, and individuals with cholesteatoma.

Diagnosis of mastoiditis involves a physical examination, blood tests, ear swab for culture and sensitivities, and imaging studies like contrast-enhanced CT or MRI. Treatment typically involves referral to an ear, nose, and throat specialist, broad-spectrum intravenous antibiotics, pain relief, and myringotomy (a procedure to drain fluid from the middle ear).

Complications of mastoiditis are rare but can be serious. They include intracranial abscess, meningitis, subperiosteal abscess, neck abscess, venous sinus thrombosis, cranial nerve palsies, hearing loss, labyrinthitis, extension to the zygoma, and carotid artery arteritis. However, most patients with mastoiditis have a good prognosis and do not experience long-term ear problems.

The initial stage of SJS is characterized by a rash on the skin, specifically on the macular area. As the condition progresses, the rash transforms into blisters, known as bullae, which eventually detach from the skin.

Further Reading:

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe mucocutaneous immune reactions characterized by blistering skin rash and erosions/ulceration of mucous membranes. SJS has less than 10% total body surface area (TBSA) involvement, SJS/TEN overlap has 10% to 30% TBSA involvement, and TEN has more than 30% TBSA involvement. The exact cause of SJS and TEN is not well understood, but it is believed to be a T-cell–mediated cytotoxic reaction triggered by drugs, infections, or vaccinations. Drugs are responsible for 50% of SJS cases and up to 95% of TEN cases, with antibiotics and anticonvulsants being the most common culprits.

The clinical features of SJS and TEN include a prodrome of malaise, fever, headache, and cough, followed by the appearance of small pink-red macules with darker centers. These macules can coalesce and develop into larger blisters (bullae) that eventually break and cause the epidermis to slough off. Painful mucosal erosions can also occur, affecting various parts of the body and leading to complications such as renal failure, hepatitis, pneumonia, and urethritis. Nikolsky’s sign, which refers to the easy sloughing off of the epidermal layer with pressure, is a characteristic feature of SJS and TEN.

The diagnosis of SJS, SJS/TEN overlap, and TEN can be confirmed through a skin biopsy, which typically shows desquamation at the epidermal-papillary dermal junction and the presence of necrotic epithelium and lymphocytes. Management of SJS and TEN involves supportive care, withdrawal of the causative agent if drug-related, monitoring for metabolic derangement and infection, maintaining the airway, treating respiratory function and pneumonia, fluid resuscitation, wound care, analgesia, and nutritional support. Ophthalmology consultation is also recommended. Intravenous immunoglobulin, ciclosporin, corticosteroids, and plasmapheresis may be used in treatment, but there is limited evidence supporting their effectiveness.

The prognosis of SJS and TEN can be assessed using the SCORTEN score, which comprises of 7 clinical and biological parameters, with the predicted probability of mortality ranging from 3.2% to 90.0%.

The first-rank symptoms of schizophrenia, as described by Kurt Schneider, include auditory hallucinations such as hearing 3rd person voices discussing the patient, experiencing thought echo, and receiving commentary on one’s actions. Additionally, passivity phenomena may occur, such as thought insertion, thought withdrawal, thought broadcast, and feelings of thoughts and actions being under external control. Delusions, which can be primary or secondary, are also common in schizophrenia.

On the other hand, chronic schizophrenia is characterized by negative symptoms. These include poor motivation and self-care, social withdrawal, depression, flat and blunted affect, emotional incongruity, decreased activity, and poverty of thought and speech. These symptoms are often present in individuals with chronic schizophrenia.

Anhydrosis, or the inability to sweat, is frequently observed in individuals who experience heat stroke. This patient exhibits the main characteristics of heat stroke, including a core body temperature exceeding 40ºC and encephalopathy, which is evident through significant confusion. Additionally, the patient’s use of diuretics and advanced age are risk factors that increase the likelihood of developing severe heat-related illness. It is important to note that in the UK, most fatalities resulting from heat stroke occur in individuals aged 70 or older, typically within the initial days of a heat wave.

Further Reading:

Heat Stroke:
– Core temperature >40°C with central nervous system dysfunction
– Classified into classic/non-exertional heat stroke and exertional heat stroke
– Classic heat stroke due to passive exposure to severe environmental heat
– Exertional heat stroke due to strenuous physical activity in combination with excessive environmental heat
– Mechanisms to reduce core temperature overwhelmed, leading to tissue damage
– Symptoms include high body temperature, vascular endothelial surface damage, inflammation, dehydration, and renal failure
– Management includes cooling methods and supportive care
– Target core temperature for cooling is 38.5°C

Heat Exhaustion:
– Mild to moderate heat illness that can progress to heat stroke if untreated
– Core temperature elevated but <40°C
– Symptoms include nausea, vomiting, dizziness, and mild neurological symptoms
– Normal thermoregulation is disrupted
– Management includes moving patient to a cooler environment, rehydration, and rest

Other Heat-Related Illnesses:
– Heat oedema: transitory swelling of hands and feet, resolves spontaneously
– Heat syncope: results from volume depletion and peripheral vasodilatation, managed by moving patient to a cooler environment and rehydration
– Heat cramps: painful muscle contractions associated with exertion, managed with cooling, rest, analgesia, and rehydration

Risk Factors for Severe Heat-Related Illness:
– Old age, very young age, chronic disease and debility, mental illness, certain medications, housing issues, occupational factors

Management:
– Cooling methods include spraying with tepid water, fanning, administering cooled IV fluids, cold or ice water immersion, and ice packs
– Benzodiazepines may be used to control shivering
– Rapid cooling to achieve rapid normothermia should be avoided to prevent overcooling and hypothermia
– Supportive care includes intravenous fluid replacement, seizure treatment if required, and consideration of haemofiltration
– Some patients may require liver transplant due to significant liver damage
– Patients with heat stroke should ideally be managed in a HDU/ICU setting with CVP and urinary catheter output measurements

The management of anaphylaxis involves several important steps. First and foremost, it is crucial to ensure proper airway management. Additionally, early administration of adrenaline is essential, preferably in the anterolateral aspect of the middle third of the thigh. Aggressive fluid resuscitation is also necessary. In severe cases, intubation may be required. However, it is important to note that the administration of chlorpheniramine and hydrocortisone should only be considered after early resuscitation has taken place.

Adrenaline is the most vital medication for treating anaphylactic reactions. It acts as an alpha-adrenergic receptor agonist, which helps reverse peripheral vasodilatation and reduce oedema. Furthermore, its beta-adrenergic effects aid in dilating the bronchial airways, increasing the force of myocardial contraction, and suppressing histamine and leukotriene release. Administering adrenaline as the first drug is crucial, and the intramuscular (IM) route is generally the most effective for most individuals.

The recommended doses of IM adrenaline for different age groups during anaphylaxis are as follows:

– Children under 6 years: 150 mcg (0.15 mL of 1:1000)
– Children aged 6-12 years: 300 mcg (0.3 mL of 1:1000)
– Children older than 12 years: 500 mcg (0.5 mL of 1:1000)
– Adults: 500 mcg (0.5 mL of 1:1000)