Acute kidney injury (AKI), previously known as acute renal failure, is a sudden decline in kidney function. This results in the accumulation of waste products and disturbances in fluid and electrolyte balance. AKI can occur in individuals with previously normal kidney function or those with pre-existing kidney disease, known as acute-on-chronic kidney disease. It is a relatively common condition, with approximately 15% of adults admitted to hospitals in the UK developing AKI.

The causes of AKI can be categorized into pre-renal, intrinsic renal, and post-renal factors. The majority of AKI cases in the community are due to pre-renal causes, accounting for 90% of cases. These are often associated with conditions such as hypotension from sepsis or fluid depletion. Medications, particularly ACE inhibitors and NSAIDs, are also frequently implicated in AKI.

The table below summarizes the most common causes of AKI:

Pre-renal:
– Volume depletion (e.g., hemorrhage, severe vomiting or diarrhea, burns)
– Oedematous states (e.g., cardiac failure, liver cirrhosis, nephrotic syndrome)
– Hypotension (e.g., cardiogenic shock, sepsis, anaphylaxis)
– Cardiovascular conditions (e.g., severe cardiac failure, arrhythmias)
– Renal hypoperfusion: NSAIDs, COX-2 inhibitors, ACE inhibitors or ARBs, Abdominal aortic aneurysm
– Renal artery stenosis
– Hepatorenal syndrome

Intrinsic renal:
– Glomerular disease (e.g., glomerulonephritis, thrombosis, hemolytic-uremic syndrome)
– Tubular injury: acute tubular necrosis (ATN) following prolonged ischemia
– Acute interstitial nephritis due to drugs (e.g., NSAIDs), infection, or autoimmune diseases
– Vascular disease (e.g., vasculitis, polyarteritis nodosa, thrombotic microangiopathy, cholesterol emboli, renal vein thrombosis, malignant hypertension)
– Eclampsia

Post-renal:
– Renal stones
– Blood clot
– Papillary necrosis
– Urethral stricture
– Prostatic hypertrophy or malignancy
– Bladder tumor
– Radiation fibrosis
– Pelvic malignancy
– Retroperitoneal fibrosis

The British Society of Gastroenterology (BSG) has developed guidelines for healthcare professionals who are assessing cases of acute lower intestinal bleeding in a hospital setting. These guidelines are particularly useful when determining which patients should be referred for further evaluation.

When patients present with lower gastrointestinal bleeding (LGIB), they should be categorized as either unstable or stable. Unstable patients are defined as those with a shock index greater than 1, which is calculated by dividing the heart rate by the systolic blood pressure (HR/SBP).

For stable patients, the next step is to determine whether their bleed is major (requiring hospitalization) or minor (suitable for outpatient management). This can be determined using a risk assessment tool called the Oakland risk score, which takes into account factors such as age, hemoglobin level, and findings from a digital rectal examination.

Patients with a minor self-limiting bleed (e.g., an Oakland score of less than 8 points) and no other indications for hospital admission can be discharged with urgent follow-up for further investigation as an outpatient.

Patients with a major bleed should be admitted to the hospital and scheduled for a colonoscopy as soon as possible.

If a patient is hemodynamically unstable or has a shock index greater than 1 even after initial resuscitation, and there is suspicion of active bleeding, a CT angiography (CTA) should be considered. This can be followed by endoscopic or radiological therapy.

If no bleeding source is identified by the initial CTA and the patient remains stable after resuscitation, an upper endoscopy should be performed immediately, as LGIB associated with hemodynamic instability may indicate an upper gastrointestinal bleeding source. Gastroscopy may be the first investigation if the patient stabilizes after initial resuscitation.

If indicated, catheter angiography with the possibility of embolization should be performed as soon as possible after a positive CTA to increase the chances of success. In centers with a 24/7 interventional radiology service, this procedure should be available within 60 minutes for hemodynamically unstable patients.

Emergency laparotomy should only be considered if all efforts to locate the bleeding using radiological and/or endoscopic methods have been exhausted, except in exceptional circumstances.

In some cases, red blood cell transfusion may be necessary. It is recommended to use restrictive blood transfusion thresholds, such as a hemoglobin trigger of 7 g/dL and a target of 7-9 g/d

When administering adrenaline through the ET tube in pediatric cardiac arrest, the recommended dose is 100 mcg/kg. In this particular scenario, the child weighs 25 kg, so the appropriate amount to administer would be 2500 mcg (equivalent to 2.5 mg).

In order to achieve satisfactory bronchodilation, most individuals require a plasma theophylline concentration of 10-20 mg/litre (55-110 micromol/litre). However, it is possible for a lower concentration to still be effective. Adverse effects can occur within the range of 10-20 mg/litre, and their frequency and severity increase when concentrations exceed 20 mg/litre.

To measure plasma theophylline concentration, a blood sample should be taken five days after starting oral treatment and at least three days after any dose adjustment. For modified-release preparations, the blood sample should typically be taken 4-6 hours after an oral dose (specific sampling times may vary, so it is advisable to consult local guidelines). If aminophylline is administered intravenously, a blood sample should be taken 4-6 hours after initiating treatment.

Ciprofloxacin is known to inhibit the activity of cytochrome P450 enzymes, which can lead to increased levels of theophylline in the blood. Therefore, it is recommended to avoid prescribing ciprofloxacin and theophylline together. For more information on the interactions between these two medications, you can refer to the relevant section on theophylline interactions in the British National Formulary (BNF).

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.

The recommended first-line antibiotics for eradicating H. pylori are amoxicillin in combination with either clarithromycin or metronidazole. According to NICE guidelines, for H. pylori-associated ulcers not caused by NSAID use, a 7-day eradication therapy is advised. This therapy consists of taking amoxicillin 1 g twice daily, along with either clarithromycin 500 mg twice daily or metronidazole 400 mg twice daily. Additionally, a proton pump inhibitor should be taken twice daily, with several options available. Please refer to the yellow box at the end of the notes for appropriate PPI choices.

Further Reading:

Peptic ulcer disease (PUD) is a condition characterized by a break in the mucosal lining of the stomach or duodenum. It is caused by an imbalance between factors that promote mucosal damage, such as gastric acid, pepsin, Helicobacter pylori infection, and NSAID drug use, and factors that maintain mucosal integrity, such as prostaglandins, mucus lining, bicarbonate, and mucosal blood flow.

The most common causes of peptic ulcers are H. pylori infection and NSAID use. Other factors that can contribute to the development of ulcers include smoking, alcohol consumption, certain medications (such as steroids), stress, autoimmune conditions, and tumors.

Diagnosis of peptic ulcers involves screening for H. pylori infection through breath or stool antigen tests, as well as upper gastrointestinal endoscopy. Complications of PUD include bleeding, perforation, and obstruction. Acute massive hemorrhage has a case fatality rate of 5-10%, while perforation can lead to peritonitis with a mortality rate of up to 20%.

The symptoms of peptic ulcers vary depending on their location. Duodenal ulcers typically cause pain that is relieved by eating, occurs 2-3 hours after eating and at night, and may be accompanied by nausea and vomiting. Gastric ulcers, on the other hand, cause pain that occurs 30 minutes after eating and may be associated with nausea and vomiting.

Management of peptic ulcers depends on the underlying cause and presentation. Patients with active gastrointestinal bleeding require risk stratification, volume resuscitation, endoscopy, and proton pump inhibitor (PPI) therapy. Those with perforated ulcers require resuscitation, antibiotic treatment, analgesia, PPI therapy, and urgent surgical review.

For stable patients with peptic ulcers, lifestyle modifications such as weight loss, avoiding trigger foods, eating smaller meals, quitting smoking, reducing alcohol consumption, and managing stress and anxiety are recommended. Medication review should be done to stop causative drugs if possible. PPI therapy, with or without H. pylori eradication therapy, is also prescribed. H. pylori testing is typically done using a carbon-13 urea breath test or stool antigen test, and eradication therapy involves a 7-day triple therapy regimen of antibiotics and PPI.

Technetium 99 (Tc-99) pertechnetate scintigraphy is the preferred imaging method for evaluating frostbite. This technique is highly accurate in detecting tissue damage and provides both sensitivity and specificity.

Further Reading:

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 decreased 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.

All individuals diagnosed with stage 5 chronic kidney disease should be given the option to choose between haemodialysis or peritoneal dialysis. Peritoneal dialysis should be prioritized as the preferred treatment for the following groups of patients: those who still have some remaining kidney function, adult patients without major additional health conditions, and children who are two years old or younger.

Generally speaking, if a child shows clinical signs of dehydration but does not exhibit shock, it can be assumed that they are 5% dehydrated. On the other hand, if shock is also present, it can be assumed that the child is 10% dehydrated or more. When we say 5% dehydration, it means that the body has lost 5 grams per 100 grams of body weight, which is equivalent to 50 milliliters per kilogram of fluid. Similarly, 10% dehydration implies a fluid loss of 100 milliliters per kilogram of fluid.

In the case of this child, they are 10% dehydrated, which means they have lost 100 milliliters per kilogram of fluid. Considering their weight of 30 kilograms, their estimated fluid loss amounts to 100 multiplied by 30, which equals 3000 milliliters.

Since this child is also in shock, they should receive a fluid bolus of 20 milliliters per kilogram. Therefore, the initial volume of fluid to administer would be 20 multiplied by 30 milliliters, resulting in 600 milliliters.

To summarize the clinical features of dehydration and shock, please refer below:

Dehydration (5%):
– The child appears unwell
– Normal heart rate or tachycardia
– Normal respiratory rate or tachypnea
– Normal peripheral pulses
– Normal or mildly prolonged capillary refill time (CRT)
– Normal blood pressure
– Warm extremities
– Decreased urine output
– Reduced skin turgor
– Sunken eyes
– Depressed fontanelle
– Dry mucous membranes

Clinical shock (10%):
– Pale, lethargic, mottled appearance
– Tachycardia
– Tachypnea
– Weak peripheral pulses
– Prolonged capillary refill time (CRT)
– Hypotension
– Cold extremities
– Decreased urine output
– Decreased level of consciousness