Nitrofurantoin is currently the preferred antibiotic for treating uncomplicated urinary tract infections in non-pregnant women. However, antibiotic resistance is becoming a significant concern in the management of urinary tract infections and pyelonephritis in the UK. In England, the resistance of E. coli (the main bacteria causing these infections) to certain antibiotics is as follows:

Trimethoprim: 30.3% (varies between areas from 27.1% to 33.4%)
Co-amoxiclav: 19.8% (varies between areas from 10.8% to 30.7%)
Ciprofloxacin: 10.6% (varies between areas from 7.8% to 13.7%)
Cefalexin: 9.9% (varies between areas from 8.1% to 11.4%)

Erythroderma is a condition characterized by widespread redness affecting more than 90% of the body surface. It is also known as exfoliative erythroderma due to the presence of skin exfoliation. Another term used to describe this condition is the red man syndrome.

The clinical features of exfoliative erythroderma include the rapid spread of redness to cover more than 90% of the body surface. Scaling of the skin occurs between days 2 and 6, leading to thickening of the skin. Despite the skin feeling hot, patients often experience a sensation of coldness. Keratoderma, which is the thickening of the skin on the palms and soles, may develop. Over time, erythema and scaling of the scalp can result in hair loss. The nails may become thickened, ridged, and even lost. Lymphadenopathy, or enlarged lymph nodes, is a common finding. In some cases, the patient’s overall health may be compromised.

Exfoliative erythroderma can be caused by various factors, including eczema (with atopic dermatitis being the most common underlying cause), psoriasis, lymphoma and leukemia (with cutaneous T-cell lymphoma and Hodgkin lymphoma being the most common malignant causes), certain drugs (more than 60 drugs have been implicated, with sulphonamides, isoniazid, penicillin, antimalarials, phenytoin, captopril, and cimetidine being the most commonly associated), idiopathic (unknown cause), and rare conditions such as pityriasis rubra pilaris and pemphigus foliaceus. Withdrawal of corticosteroids, underlying infections, hypocalcemia, and the use of strong coal tar preparations can also precipitate exfoliative erythroderma.

Potential complications of exfoliative erythroderma include dehydration, hypothermia, cardiac failure, overwhelming secondary infection, protein loss and edema, anemia (due to loss of iron, B12, and folate), and lymphadenopathy.

Management of exfoliative erythroderma should involve referring the patient to the medical on-call team and dermatology for admission. It is important to keep the patient warm and start intravenous fluids, such as warmed 0.9% saline. Applying generous amounts of emollients and wet dressings can help alleviate

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.

Calcium-channel blocker overdose is a serious condition that should always be taken seriously as it can be potentially life-threatening. The two most dangerous types of calcium channel blockers in overdose are verapamil and diltiazem. These medications work by binding to the alpha-1 subunit of L-type calcium channels, which prevents the entry of calcium into the cells. These channels play a crucial role in the functioning of cardiac myocytes, vascular smooth muscle cells, and islet beta-cells.

Significant toxicity can occur with the ingestion of more than 10 tablets of verapamil (160 mg or 240 mg immediate or sustained-release capsules) or diltiazem (180 mg, 240 mg or 360 mg immediate or sustained-release capsules). In children, even 1-2 tablets of immediate or sustained-release verapamil or diltiazem can be harmful. Symptoms usually appear within 1-2 hours of taking standard preparations, but with slow-release versions, the onset of severe toxicity may be delayed by 12-16 hours, with peak effects occurring after 24 hours.

The main clinical manifestations of calcium-channel blocker overdose include nausea and vomiting, low blood pressure, slow heart rate and first-degree heart block, heart muscle ischemia and stroke, kidney failure, pulmonary edema, and high blood sugar levels.

When managing a patient with calcium-channel blocker overdose, certain bedside investigations are crucial. These include checking blood glucose levels, performing an electrocardiogram (ECG), and obtaining an arterial blood gas sample. Additional investigations that can provide helpful information include assessing urea and electrolyte levels, conducting a chest X-ray to check for pulmonary edema, and performing an echocardiography.

This individual has developed Dupuytren’s contracture, which is a hand deformity characterized by a fixed flexion caused by palmar fibromatosis. The only anticonvulsant treatment believed to be connected to the development of Dupuytren’s contracture is phenytoin. Additionally, other conditions associated with its occurrence include liver cirrhosis, diabetes mellitus, alcoholism, and trauma.

This patient is displaying symptoms and signs that are consistent with an atypical pneumonia, most likely caused by an infection from Mycoplasma pneumoniae. The clinical features commonly associated with Mycoplasma pneumoniae infection include a flu-like illness that occurs before respiratory symptoms, fever, myalgia, headache, diarrhea, and cough (initially dry but often becoming productive). Focal chest signs typically develop later in the course of the illness. It is worth noting that Mycoplasma pneumoniae is frequently linked to the development of erythema multiforme and can also be a cause of Steven-Johnson syndrome. The rash associated with erythema multiforme is characterized by multiple red lesions on the limbs that develop into target lesions a few days after the rash first appears.

The administration of nitrous oxide increases the amount of inhaled anaesthetic gases in the body through a phenomenon called the ‘second gas effect’. Nitrous oxide is much more soluble than nitrogen, with a solubility that is 20 to 30 times higher. When nitrous oxide is given, it causes a decrease in the volume of air in the alveoli. Additionally, nitrous oxide can enhance the absorption of other inhaled anaesthetic agents through the second gas effect. However, it is important to note that nitrous oxide alone cannot be used as the sole maintenance agent in anaesthesia.

Further Reading:

Entonox® is a mixture of 50% nitrous oxide and 50% oxygen that can be used for self-administration to reduce anxiety. It can also be used alongside other anesthesia agents. However, its mechanism of action for anxiety reduction is not fully understood. The Entonox bottles are typically identified by blue and white color-coded collars, but a new standard will replace these with dark blue shoulders in the future. It is important to note that Entonox alone cannot be used as the sole maintenance agent in anesthesia.

One of the effects of nitrous oxide is the second-gas effect, where it speeds up the absorption of other inhaled anesthesia agents. Nitrous oxide enters the alveoli and diffuses into the blood, displacing nitrogen. This displacement causes the remaining alveolar gases to become more concentrated, increasing the fractional content of inhaled anesthesia gases and accelerating the uptake of volatile agents into the blood.

However, when nitrous oxide administration is stopped, it can cause diffusion hypoxia. Nitrous oxide exits the blood and diffuses back into the alveoli, while nitrogen diffuses in the opposite direction. Nitrous oxide enters the alveoli much faster than nitrogen leaves, resulting in the dilution of oxygen within the alveoli. This can lead to diffusion hypoxia, where the oxygen concentration in the alveoli is diluted, potentially causing oxygen deprivation in patients breathing air.

There are certain contraindications for using nitrous oxide, as it can expand in air-filled spaces. It should be avoided in conditions such as head injuries with intracranial air, pneumothorax, recent intraocular gas injection, and entrapped air following a recent underwater dive.

The post-cardiac arrest syndrome consists of four components. The first component is post-cardiac arrest brain injury, which refers to any damage or impairment to the brain that occurs after a cardiac arrest. The second component is post-cardiac arrest myocardial dysfunction, which is a condition where the heart muscle does not function properly after a cardiac arrest.

Further Reading:

Cardiopulmonary arrest is a serious event with low survival rates. In non-traumatic cardiac arrest, only about 20% of patients who arrest as an in-patient survive to hospital discharge, while the survival rate for out-of-hospital cardiac arrest is approximately 8%. The Resus Council BLS/AED Algorithm for 2015 recommends chest compressions at a rate of 100-120 per minute with a compression depth of 5-6 cm. The ratio of chest compressions to rescue breaths is 30:2.

After a cardiac arrest, the goal of patient care is to minimize the impact of post cardiac arrest syndrome, which includes brain injury, myocardial dysfunction, the ischaemic/reperfusion response, and the underlying pathology that caused the arrest. The ABCDE approach is used for clinical assessment and general management. Intubation may be necessary if the airway cannot be maintained by simple measures or if it is immediately threatened. Controlled ventilation is aimed at maintaining oxygen saturation levels between 94-98% and normocarbia. Fluid status may be difficult to judge, but a target mean arterial pressure (MAP) between 65 and 100 mmHg is recommended. Inotropes may be administered to maintain blood pressure. Sedation should be adequate to gain control of ventilation, and short-acting sedating agents like propofol are preferred. Blood glucose levels should be maintained below 8 mmol/l. Pyrexia should be avoided, and there is some evidence for controlled mild hypothermia but no consensus on this.

Post ROSC investigations may include a chest X-ray, ECG monitoring, serial potassium and lactate measurements, and other imaging modalities like ultrasonography, echocardiography, CTPA, and CT head, depending on availability and skills in the local department. Treatment should be directed towards the underlying cause, and PCI or thrombolysis may be considered for acute coronary syndrome or suspected pulmonary embolism, respectively.

Patients who are comatose after ROSC without significant pre-arrest comorbidities should be transferred to the ICU for supportive care. Neurological outcome at 72 hours is the best prognostic indicator of outcome.

Discitis is an infection that affects the space between the intervertebral discs in the spine. This condition can have serious consequences, including the formation of abscesses and sepsis. The most common cause of discitis is usually Staphylococcus aureus, but other organisms like Streptococcus viridans and Pseudomonas aeruginosa may be responsible in intravenous drug users and those with weakened immune systems. Gram-negative organisms such as Escherichia coli and Mycobacterium tuberculosis can also cause discitis.

There are several risk factors that increase the likelihood of developing discitis. These include having undergone spinal surgery (which occurs in 1-2% of cases post-operatively), having an immunodeficiency, being an intravenous drug user, being under the age of eight, having diabetes mellitus, or having a malignancy.

The typical symptoms of discitis include back or neck pain (which occurs in over 90% of cases), pain that often wakes the patient from sleep, fever (present in 60-70% of cases), and neurological deficits (which can occur in up to 50% of cases). In children, refusal to walk may also be a symptom.

When diagnosing discitis, MRI is the preferred imaging modality due to its high sensitivity and specificity. It is important to image the entire spine, as discitis often affects multiple levels. Plain radiographs are not very sensitive to the early changes of discitis and may appear normal for 2-4 weeks. CT scanning is also not very sensitive in detecting discitis.

Treatment for discitis involves admission to the hospital for intravenous antibiotics. Before starting the antibiotics, it is important to send three sets of blood cultures and a full set of blood tests, including a CRP, to the lab. The choice of antibiotics depends on the specific situation. A typical antibiotic regimen for discitis may include IV flucloxacillin as the first-line treatment if there is no penicillin allergy, IV vancomycin if the infection was acquired in the hospital or there is a high risk of MRSA, and possibly IV gentamicin if there is a possibility of a Gram-negative infection. In cases where there is acute kidney injury and Gram-negative cover is required, IV piperacillin-tazobactam alone may be used.

If a child with gastroenteritis shows signs of jittery movements, increased muscle tone, hyper-reflexia, or convulsions, hypernatraemic dehydration should be considered. Additional signs of hypernatraemic dehydration include drowsiness or coma.

Further Reading:

Gastroenteritis is a common condition in children, particularly those under the age of 5. It is characterized by the sudden onset of diarrhea, with or without vomiting. The most common cause of gastroenteritis in infants and young children is rotavirus, although other viruses, bacteria, and parasites can also be responsible. Prior to the introduction of the rotavirus vaccine in 2013, rotavirus was the leading cause of gastroenteritis in children under 5 in the UK. However, the vaccine has led to a significant decrease in cases, with a drop of over 70% in subsequent years.

Norovirus is the most common cause of gastroenteritis in adults, but it also accounts for a significant number of cases in children. In England & Wales, there are approximately 8,000 cases of norovirus each year, with 15-20% of these cases occurring in children under 9.

When assessing a child with gastroenteritis, it is important to consider whether there may be another more serious underlying cause for their symptoms. Dehydration assessment is also crucial, as some children may require intravenous fluids. The NICE traffic light system can be used to identify the risk of serious illness in children under 5.

In terms of investigations, stool microbiological testing may be indicated in certain cases, such as when the patient has been abroad, if diarrhea lasts for more than 7 days, or if there is uncertainty over the diagnosis. U&Es may be necessary if intravenous fluid therapy is required or if there are symptoms and/or signs suggestive of hypernatremia. Blood cultures may be indicated if sepsis is suspected or if antibiotic therapy is planned.

Fluid management is a key aspect of treating children with gastroenteritis. In children without clinical dehydration, normal oral fluid intake should be encouraged, and oral rehydration solution (ORS) supplements may be considered. For children with dehydration, ORS solution is the preferred method of rehydration, unless intravenous fluid therapy is necessary. Intravenous fluids may be required for children with shock or those who are unable to tolerate ORS solution.

Antibiotics are generally not required for gastroenteritis in children, as most cases are viral or self-limiting. However, there are some exceptions, such as suspected or confirmed sepsis, Extraintestinal spread of bacterial infection, or specific infections like Clostridium difficile-associated pseudomembranous enterocolitis or giardiasis.

NSAIDs are known to have a relaxing effect on the ureter, but a randomized controlled trial found no difference between NSAIDs and a placebo in terms of this effect. Currently, only two classes of drugs, calcium channel blockers and alpha-blockers, are considered effective as medical expulsive therapy (MET). Calcium channel blockers work by blocking the active calcium channel pump that the smooth muscle of the ureter uses to contract, resulting in relaxation of the muscle and improved stone passage. Alpha-blockers, on the other hand, are commonly used as the first-line treatment to enhance stone passage. They reduce the basal tone of the ureter smooth muscle, decrease the frequency of peristaltic waves, and lower ureteric contraction. This leads to a decrease in intraureteric pressure below the stone, increasing the chances of stone passage. Patients treated with calcium channel blockers or alpha-blockers have been shown to have a 65% higher likelihood of spontaneous stone passage compared to those not given these medications.

Peptic ulcer disease is a fairly common condition that can affect either the stomach or the duodenum. However, the duodenum is more commonly affected, and in these cases, it is caused by a break in the mucosal lining of the duodenum.

This condition is more prevalent in men and is most commonly seen in individuals between the ages of 20 and 60. In fact, over 95% of patients with duodenal ulcers are found to be infected with H. pylori. Additionally, chronic usage of nonsteroidal anti-inflammatory drugs (NSAIDs) is often associated with the development of duodenal ulcers.

When it comes to the location of duodenal ulcers, they are most likely to occur in the superior (first) part of the duodenum, which is positioned in front of the body of the L1 vertebra.

The typical clinical features of duodenal ulcers include experiencing epigastric pain that radiates to the back, with the pain often worsening at night. This pain typically occurs 2-3 hours after eating and is relieved by consuming food and drinking milk. It can also be triggered by skipping meals or experiencing stress.

Possible complications that can arise from duodenal ulcers include perforation, which can lead to peritonitis, as well as gastrointestinal hemorrhage. Gastrointestinal hemorrhage can manifest as haematemesis (vomiting blood), melaena (black, tarry stools), or occult bleeding. Strictures causing obstruction can also occur as a result of duodenal ulcers.

In cases where gastrointestinal hemorrhage occurs as a result of duodenal ulceration, it is usually due to erosion of the gastroduodenal artery.

Supraventricular tachycardia (SVT) is the most common arrhythmia that occurs in children and infants, causing cardiovascular instability. According to the current APLS guidelines, if a patient with SVT shows no signs of shock and remains stable, initial attempts should be made to use vagal maneuvers. If these maneuvers are unsuccessful, the following steps are recommended:

– Administer an initial dose of 100 mcg/kg of adenosine.
– After two minutes, if the child is still in stable SVT, administer another dose of 200 mcg/kg of adenosine.
– After an additional two minutes, if the child remains in stable SVT, administer another dose of 300 mcg/kg of adenosine.

If these measures do not resolve the SVT, the guidelines suggest considering the following options:

– Administer adenosine at a dose of 400-500 mcg/kg.
– Perform a synchronous DC shock.
– Administer amiodarone.

When using amiodarone, the initial dose should be 5-10 mg/kg given over a period of 20 minutes to 2 hours. This should be followed by a continuous infusion of 300 mcg/kg/hour, with adjustments made based on the response, increasing by 1.5 mg/kg/hour. The total infusion rate should not exceed 1.2 g in a 24-hour period.

If defibrillation is necessary for the treatment of SVT in children, it should be performed as a DC synchronous shock at a dosage of 1-2 J/kg.

Discitis is an infection that affects the space between the intervertebral discs in the spine. This condition can have serious consequences, including the formation of abscesses and sepsis. The most common cause of discitis is usually Staphylococcus aureus, but other organisms like Streptococcus viridans and Pseudomonas aeruginosa may be responsible in certain cases, especially in immunocompromised individuals and intravenous drug users. Gram-negative organisms like Escherichia coli and Mycobacterium tuberculosis can also cause discitis, particularly in cases of Pott’s disease.

There are several risk factors that increase the likelihood of developing discitis. These include having undergone spinal surgery (which occurs in about 1-2% of patients post-operatively), having an immunodeficiency, being an intravenous drug user, being under the age of eight, having diabetes mellitus, or having a malignancy.

The typical symptoms of discitis include back or neck pain (which occurs in over 90% of cases), pain that often wakes the patient from sleep, fever (present in 60-70% of cases), and neurological deficits (which can occur in up to 50% of cases). In children, a refusal to walk may also be a symptom.

When diagnosing discitis, magnetic resonance imaging (MRI) is the preferred imaging modality due to its high sensitivity and specificity. It is important to image the entire spine, as discitis often affects multiple levels. Plain radiographs are not very sensitive to the early changes of discitis and may appear normal for 2-4 weeks. Computed tomography (CT) scanning is also not very sensitive in detecting discitis.

Treatment for discitis involves hospital admission for intravenous antibiotics. Before starting the antibiotics, it is recommended to send three sets of blood cultures and a full set of blood tests, including a C-reactive protein (CRP) test, to the laboratory.

A typical antibiotic regimen for discitis would include intravenous flucloxacillin 2 g every 6 hours as the first-line treatment if there is no penicillin allergy. Intravenous vancomycin may be used if the infection was acquired in the hospital, if there is a high risk of methicillin-resistant Staphylococcus aureus (MRSA) infection, or if there is a documented penicillin allergy.

The interpretation of facial X-rays is often assisted by the use of McGrigor-Campbell lines and Dolan lines. These lines, along with accompanying notes and images, provide additional information for a more accurate analysis.

Further Reading:

Facial X-rays are commonly used to assess and diagnose facial fractures. Two standard views are typically performed: the Occipitomental view and the Occipitomental 30º view. The Occipitomental view provides a comprehensive look at the upper and middle thirds of the face, including the orbital margins, frontal sinuses, zygomatic arches, and maxillary antra. On the other hand, the Occipitomental 30º view uses a 30-degree caudal angulation to better visualize the zygomatic arches and walls of the maxillary antra, although it may compromise the clear view of the orbital margins.

To assist in the interpretation of facial X-rays, imaginary lines are often drawn across the images to highlight any asymmetry or disruption. Two commonly used sets of lines are the McGrigor-Campbell lines and Dolan’s lines. McGrigor-Campbell lines are used to aid in the interpretation of both the Occipitomental and Occipitomental 30º views. These lines include an upper line that passes through the zygomatico-frontal sutures and the upper edge of the orbits, a middle line that follows the zygomatic arch and crosses the zygomatic bone, and a lower line that passes through the condyle and coronoid process of the mandible and the walls of the maxillary antra.

Dolan’s lines, described by Dolan and Jacoby, are often used in conjunction with McGrigor-Campbell lines. These lines include the orbital line, which traces the inner margins of the orbital walls and the nasal arch, the zygomatic line, which traces the superior margin of the zygomatic arch and body, and the maxillary line, which traces the inferior margin of the zygomatic arch, body, and buttress, as well as the lateral wall of the maxillary sinus. Together, the zygomatic and maxillary lines resemble the profile of an elephant’s head and are referred to as Dolan’s elephant. These lines help provide additional information and aid in the interpretation of facial X-rays.

NSAIDs are known to have a relaxing effect on the ureter, but a randomized controlled trial found no difference between NSAIDs and a placebo in terms of this effect. Currently, only two classes of drugs, calcium channel blockers and alpha-blockers, are considered effective as medical expulsive therapy (MET). Calcium channel blockers work by blocking the active calcium channel pump that the smooth muscle of the ureter uses to contract, resulting in relaxation of the muscle and improved stone passage. Alpha-blockers, on the other hand, are commonly used as the first-line treatment to enhance stone passage. They reduce the basal tone of the ureter smooth muscle, decrease the frequency of peristaltic waves, and lower ureteric contraction. This leads to a decrease in intraureteric pressure below the stone, increasing the chances of stone passage. Patients treated with calcium channel blockers or alpha-blockers have been shown to have a 65% higher likelihood of spontaneous stone passage compared to those not given these medications.

Lithium is a medication used to stabilize mood and is approved for the treatment and prevention of mania, bipolar disorder, recurrent depression, and aggressive or self-harming behavior. During pregnancy and the postnatal period, it is important to monitor lithium levels more frequently. If taken during the first trimester, lithium is associated with an increased risk of fetal cardiac malformations, such as Ebstein’s anomaly. If taken during the second and third trimesters, there is a risk of various complications in the newborn, including hypotonia, lethargy, feeding problems, hypothyroidism, goiter, and nephrogenic diabetes insipidus.

Here is a list outlining commonly encountered drugs that have adverse effects during pregnancy:

Drug: ACE inhibitors (e.g. ramipril)
Adverse effects: If taken during the second and third trimesters, ACE inhibitors can cause hypoperfusion, renal failure, and the oligohydramnios sequence.

Drug: Aminoglycosides (e.g. gentamicin)
Adverse effects: Aminoglycosides can cause ototoxicity and deafness in the fetus.

Drug: Aspirin
Adverse effects: High doses of aspirin can lead to 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 a significant risk.

Drug: Benzodiazepines (e.g. diazepam)
Adverse effects: When taken late in pregnancy, benzodiazepines can cause respiratory depression and a neonatal withdrawal syndrome.

Drug: Calcium-channel blockers
Adverse effects: If taken during the first trimester, calcium-channel blockers can cause phalangeal abnormalities. If taken during the second and third trimesters, they can lead to fetal growth retardation.

Digoxin is eliminated through the kidneys, and if renal function is compromised, it can lead to elevated levels of digoxin and potential toxicity. To address this issue, it is necessary to decrease the patient’s digoxin dosage and closely monitor their digoxin levels and electrolyte levels.

The emergency department doctor does not play a role in obtaining consent from the next of kin for tissue or organ donation. Instead, it is important to involve the Specialist Nurse in Organ Donation (SNOD) as early as possible. The SNOD can provide valuable support and guidance to both the medical team and the family. They will assess the patient’s suitability for organ donation and approach the next of kin for consent, if appropriate. On the other hand, for tissue donation, a referral should be made to the tissue donation national referral centre. Retrievals can take place within 24 hours after death. In the UK, referrals can be made by phone to the tissue donation national referral centre (the contact number can be found in the notes below). It is important to note that the responsibility of gaining consent from the next of kin does not fall on the emergency department doctor.

Further Reading:

Cardiopulmonary arrest is a serious event with low survival rates. In non-traumatic cardiac arrest, only about 20% of patients who arrest as an in-patient survive to hospital discharge, while the survival rate for out-of-hospital cardiac arrest is approximately 8%. The Resus Council BLS/AED Algorithm for 2015 recommends chest compressions at a rate of 100-120 per minute with a compression depth of 5-6 cm. The ratio of chest compressions to rescue breaths is 30:2.

After a cardiac arrest, the goal of patient care is to minimize the impact of post cardiac arrest syndrome, which includes brain injury, myocardial dysfunction, the ischaemic/reperfusion response, and the underlying pathology that caused the arrest. The ABCDE approach is used for clinical assessment and general management. Intubation may be necessary if the airway cannot be maintained by simple measures or if it is immediately threatened. Controlled ventilation is aimed at maintaining oxygen saturation levels between 94-98% and normocarbia. Fluid status may be difficult to judge, but a target mean arterial pressure (MAP) between 65 and 100 mmHg is recommended. Inotropes may be administered to maintain blood pressure. Sedation should be adequate to gain control of ventilation, and short-acting sedating agents like propofol are preferred. Blood glucose levels should be maintained below 8 mmol/l. Pyrexia should be avoided, and there is some evidence for controlled mild hypothermia but no consensus on this.

Post ROSC investigations may include a chest X-ray, ECG monitoring, serial potassium and lactate measurements, and other imaging modalities like ultrasonography, echocardiography, CTPA, and CT head, depending on availability and skills in the local department. Treatment should be directed towards the underlying cause, and PCI or thrombolysis may be considered for acute coronary syndrome or suspected pulmonary embolism, respectively.

Patients who are comatose after ROSC without significant pre-arrest comorbidities should be transferred to the ICU for supportive care. Neurological outcome at 72 hours is the best prognostic indicator of outcome.

Hypothermia is defined as a core temperature below 35ºC and can be graded as mild, moderate, severe, or profound based on the core temperature. When the core temperature drops, the basal metabolic rate decreases and cell signaling between neurons decreases, leading to reduced tissue perfusion. This can result in depressed myocardial contractility, vasoconstriction, ventilation-perfusion mismatch, and increased blood viscosity. Symptoms of hypothermia progress as the core temperature drops, starting with compensatory increases in heart rate and shivering, and eventually leading to bradyarrhythmias, prolonged PR, QRS, and QT intervals, and cardiac arrest.

In the management of hypothermic cardiac arrest, ALS should be initiated with some modifications. The pulse check during CPR should be prolonged to 1 minute due to difficulty in obtaining a pulse. Rewarming the patient is important, and mechanical ventilation may be necessary due to stiffness of the chest wall. Drug metabolism is slowed in hypothermic patients, so dosing of drugs should be adjusted or withheld. Electrolyte disturbances are common in hypothermic patients and should be corrected.

Frostbite refers to a freezing injury to human tissue and occurs when tissue temperature drops below 0ºC. It can be classified as superficial or deep, with superficial frostbite affecting the skin and subcutaneous tissues, and deep frostbite affecting bones, joints, and tendons. Frostbite can be classified from 1st to 4th degree based on the severity of the injury. Risk factors for frostbite include environmental factors such as cold weather exposure and medical factors such as peripheral vascular disease and diabetes.

Signs and symptoms of frostbite include skin changes, cold sensation or firmness to the affected area, stinging, burning, or numbness, clumsiness of the affected extremity, and excessive sweating, hyperemia, and tissue gangrene. Frostbite is diagnosed clinically and imaging may be used in some cases to assess perfusion or visualize occluded vessels. Management involves moving the patient to a warm environment, removing wet clothing, and rapidly rewarming the affected tissue. Analgesia should be given as reperfusion is painful, and blisters should be de-roofed and aloe vera applied. Compartment syndrome is a risk and should be monitored for. Severe cases may require surgical debridement of amputation.