Congenital adrenal hyperplasia (CAH) is a group of inherited disorders that are caused by autosomal recessive genes. The majority of affected patients, over 90%, have a deficiency of the enzyme 21-hydroxylase. This enzyme is encoded by the 21-hydroxylase gene, which is located on chromosome 6p21 within the HLA histocompatibility complex. The second most common cause of CAH is a deficiency of the enzyme 11-beta-hydroxylase. The condition is rare, with an incidence of approximately 1 in 500 births in the UK. It is more prevalent in the offspring of consanguineous marriages.

The deficiency of 21-hydroxylase leads to a deficiency of cortisol and/or aldosterone, as well as an excess of precursor steroids. As a result, there is an increased secretion of ACTH from the anterior pituitary, leading to adrenocortical hyperplasia.

The severity of CAH varies depending on the degree of 21-hydroxylase deficiency. Female infants often exhibit ambiguous genitalia, such as clitoral hypertrophy and labial fusion. Male infants may have an enlarged scrotum and/or scrotal pigmentation. Hirsutism, or excessive hair growth, occurs in 10% of cases.

Boys with CAH often experience a salt-losing adrenal crisis at around 1-3 weeks of age. This crisis is characterized by symptoms such as vomiting, weight loss, floppiness, and circulatory collapse.

The diagnosis of CAH can be made by detecting markedly elevated levels of the metabolic precursor 17-hydroxyprogesterone. Neonatal screening is possible, primarily through the identification of persistently elevated 17-hydroxyprogesterone levels.

In infants presenting with a salt-losing crisis, the following biochemical abnormalities are observed: hyponatremia (low sodium levels), hyperkalemia (high potassium levels), metabolic acidosis, and hypoglycemia.

Boys experiencing a salt-losing crisis will require fluid resuscitation, intravenous dextrose, and intravenous hydrocortisone.

Affected females will require corrective surgery for their external genitalia. However, they have an intact uterus and ovaries and are capable of having children.

The long-term management of both sexes involves lifelong replacement of hydrocortisone (to suppress ACTH levels).

Low-velocity gunshot wounds to the abdomen result in tissue damage through laceration and cutting. On the other hand, high-velocity gunshot wounds transfer a greater amount of kinetic energy to the abdominal viscera. These types of wounds can cause more extensive damage in the surrounding area of the missile’s path due to temporary cavitation.

When patients experience penetrating abdominal trauma as a result of gunshot wounds, certain organs are more commonly injured. The small bowel is affected in approximately 50% of cases, followed by the colon in 40% of cases. The liver is injured in around 30% of cases, while abdominal vascular structures are affected in about 25% of cases.

Please note that these statistics have been obtained from the most recent edition of the ATLS manual.

Renal colic, also known as ureteric colic, refers to a sudden and intense pain in the lower back caused by a blockage in the ureter, which is the tube that carries urine from the kidney to the bladder. This condition is commonly associated with the presence of a urinary tract stone.

The main symptoms of renal or ureteric colic include severe abdominal pain on one side, starting in the lower back or flank and radiating to the groin or genital area in men, or to the labia in women. The pain comes and goes in spasms, lasting for minutes to hours, with periods of no pain or a dull ache. Nausea, vomiting, and the presence of blood in the urine are often accompanying symptoms.

People experiencing renal or ureteric colic are usually restless and unable to find relief by lying still, which helps to distinguish this condition from peritonitis. They may have a history of previous episodes and may also present with fever and sweating if there is an associated urinary infection. Some individuals may complain of painful urination, frequent urination, and straining when the stone reaches the junction between the ureter and the bladder, as the stone irritates the detrusor muscle.

In terms of pain management, the first-line treatment for adults, children, and young people with suspected renal colic is a non-steroidal anti-inflammatory drug (NSAID), which can be administered through various routes. If NSAIDs are contraindicated or not providing sufficient pain relief, intravenous paracetamol can be offered as an alternative. Opioids may be considered if both NSAIDs and intravenous paracetamol are contraindicated or not effective in relieving pain. Antispasmodics should not be given to individuals with suspected renal colic.

For more detailed information, you can refer to the NICE guidelines on the assessment and management of renal and ureteric stones.

Adrenaline acts on all types of adrenergic receptors without preference. It is administered in doses of 1 mg every 3-5 minutes during cardiac arrest. On the other hand, Amiodarone functions by blocking voltage-gated potassium channels and is typically administered after the third shock.

Further Reading:

In the management of respiratory and cardiac arrest, several drugs are commonly used to help restore normal function and improve outcomes. Adrenaline is a non-selective agonist of adrenergic receptors and is administered intravenously at a dose of 1 mg every 3-5 minutes. It works by causing vasoconstriction, increasing systemic vascular resistance (SVR), and improving cardiac output by increasing the force of heart contraction. Adrenaline also has bronchodilatory effects.

Amiodarone is another drug used in cardiac arrest situations. It blocks voltage-gated potassium channels, which prolongs repolarization and reduces myocardial excitability. The initial dose of amiodarone is 300 mg intravenously after 3 shocks, followed by a dose of 150 mg after 5 shocks.

Lidocaine is an alternative to amiodarone in cardiac arrest situations. It works by blocking sodium channels and decreasing heart rate. The recommended dose is 1 mg/kg by slow intravenous injection, with a repeat half of the initial dose after 5 minutes. The maximum total dose of lidocaine is 3 mg/kg.

Magnesium sulfate is used to reverse myocardial hyperexcitability associated with hypomagnesemia. It is administered intravenously at a dose of 2 g over 10-15 minutes. An additional dose may be given if necessary, but the maximum total dose should not exceed 3 g.

Atropine is an antagonist of muscarinic acetylcholine receptors and is used to counteract the slowing of heart rate caused by the parasympathetic nervous system. It is administered intravenously at a dose of 500 mcg every 3-5 minutes, with a maximum dose of 3 mg.

Naloxone is a competitive antagonist for opioid receptors and is used in cases of respiratory arrest caused by opioid overdose. It has a short duration of action, so careful monitoring is necessary. The initial dose of naloxone is 400 micrograms, followed by 800 mcg after 1 minute. The dose can be gradually escalated up to 2 mg per dose if there is no response to the preceding dose.

It is important for healthcare professionals to have knowledge of the pharmacology and dosing schedules of these drugs in order to effectively manage respiratory and cardiac arrest situations.

When the paramedian branches of the basilar artery are blocked, it leads to a condition known as medial pontine syndrome. This syndrome is characterized by several symptoms. Firstly, there is contralateral hemiplegia, which refers to paralysis on the opposite side of the body due to damage to the pyramidal tracts. Additionally, there is contralateral loss of joint position sense, vibratory sense, and discriminatory touch, which occurs as a result of damage to the medial lemniscus. Lastly, individuals with medial pontine syndrome may experience double vision caused by paralysis of the lateral rectus muscle, which is due to damage to the sixth cranial nerve.

Acute limb ischaemia refers to a sudden reduction in blood flow to a limb, which puts the limb at risk of tissue death. This condition is most commonly caused by either a sudden blockage of a previously partially blocked artery by a blood clot or by an embolus that travels from another part of the body. Acute limb ischaemia is considered a medical emergency, and if not promptly treated with surgery to restore blood flow, it can lead to extensive tissue damage within six hours.

The classic signs of acute limb ischaemia are often described using the 6 Ps:
– Pain that is constant and persistent
– Absence of pulses in the ankle
– Pallor, cyanosis, or mottling of the skin
– Loss of power or paralysis in the affected limb
– Paraesthesia or reduced sensation, leading to numbness
– Feeling cold in the affected limb

It is important to be able to distinguish between ischaemia caused by a blood clot and ischaemia caused by an embolus. The following highlights the main differences:
Embolus Thrombus
– Onset is sudden, occurring within seconds to minutes – Onset is gradual, taking hours to days
– Ischaemia is usually severe due to the lack of collateral circulation – Ischaemia is less severe due to the presence of collateral circulation
– There is typically no history of claudication, and pulses may still be present in the other leg – There is often a history of claudication, and pulses may also be absent in the other leg
– Skin changes, such as marbling, may be visible in the feet. This can appear as a fine reticular blanching or mottling in the early stages, progressing to coarse, fixed mottling
– Skin changes are usually absent in cases of thrombus-induced ischaemia.

Chlamydia trachomatis is a type of Gram-negative bacteria that is responsible for causing the sexually transmitted infection known as chlamydia. This bacterium is typically either coccoid or rod-shaped in its appearance.

There are various serological variants of C. trachomatis, and each variant is associated with different patterns of disease. Specifically, types D-K of this bacterium are responsible for causing genitourinary infections.

Chlamydia is the most commonly diagnosed sexually transmitted infection in the United Kingdom and is also the leading preventable cause of infertility worldwide. Interestingly, around 50% of men infected with chlamydia do not experience any symptoms, while at least 70% of infected women remain asymptomatic. However, if left untreated, chlamydia can lead to complications such as pelvic inflammatory disease, ectopic pregnancy, and tubal infertility in women. In men, it can result in proctitis, epididymitis, and epididymo-orchitis.

Prolongation of the QT interval can lead to a dangerous ventricular arrhythmia called torsades de pointes, which can result in sudden cardiac death. There are several commonly used medications that are known to cause QT prolongation.

Low levels of potassium (hypokalaemia) and magnesium (hypomagnesaemia) can increase the risk of QT prolongation. For example, diuretics can interact with QT-prolonging drugs by causing hypokalaemia.

The QT interval varies with heart rate, and formulas are used to correct the QT interval for heart rate. Once corrected, it is referred to as the QTc interval. The QTc interval is typically reported on the ECG printout. A normal QTc interval is less than 440 ms.

If the QTc interval is greater than 440 ms but less than 500 ms, it is considered borderline. Although there may be some variation in the literature, a QTc interval within these values is generally considered borderline prolonged. In such cases, it is important to consider reducing the dose of QT-prolonging drugs or switching to an alternative medication that does not prolong the QT interval.

A prolonged QTc interval exceeding 500 ms is clinically significant and is likely to increase the risk of arrhythmia. Any medications that prolong the QT interval should be reviewed immediately.

Here are some commonly encountered drugs that are known to prolong the QT interval:

Antimicrobials:
– Erythromycin
– Clarithromycin
– Moxifloxacin
– Fluconazole
– Ketoconazole

Antiarrhythmics:
– Dronedarone
– Sotalol
– Quinidine
– Amiodarone
– Flecainide

Antipsychotics:
– Risperidone
– Fluphenazine
– Haloperidol
– Pimozide
– Chlorpromazine
– Quetiapine
– Clozapine

Antidepressants:
– Citalopram/escitalopram
– Amitriptyline
– Clomipramine
– Dosulepin
– Doxepin
– Imipramine
– Lofepramine

Antiemetics:
– Domperidone
– Droperidol
– Ondansetron/Granisetron

Others:
– Methadone
– Protein kinase inhibitors (e.g. sunitinib)

The probable underlying reason for the patient’s symptoms is central pontine myelinolysis. This condition is characterized by the destruction of the myelin sheath in the pons, a region of the brainstem. It is often caused by a rapid correction of hyponatremia, which is a low level of sodium in the blood. In this case, the patient’s serum sodium level was initially low at 117 mmol/L, and the administration of intravenous 3% sodium chloride solution caused a rapid increase in sodium levels. This sudden change in sodium concentration can lead to the development of central pontine myelinolysis. The initial improvement in the patient’s symptoms may have been due to the correction of hyponatremia, but the subsequent development of lethargy and dysarthria suggests the onset of central pontine myelinolysis.

Further Reading:

Syndrome of inappropriate antidiuretic hormone (SIADH) is a condition characterized by low sodium levels in the blood due to excessive secretion of antidiuretic hormone (ADH). ADH, also known as arginine vasopressin (AVP), is responsible for promoting water and sodium reabsorption in the body. SIADH occurs when there is impaired free water excretion, leading to euvolemic (normal fluid volume) hypotonic hyponatremia.

There are various causes of SIADH, including malignancies such as small cell lung cancer, stomach cancer, and prostate cancer, as well as neurological conditions like stroke, subarachnoid hemorrhage, and meningitis. Infections such as tuberculosis and pneumonia, as well as certain medications like thiazide diuretics and selective serotonin reuptake inhibitors (SSRIs), can also contribute to SIADH.

The diagnostic features of SIADH include low plasma osmolality, inappropriately elevated urine osmolality, urinary sodium levels above 30 mmol/L, and euvolemic. Symptoms of hyponatremia, which is a common consequence of SIADH, include nausea, vomiting, headache, confusion, lethargy, muscle weakness, seizures, and coma.

Management of SIADH involves correcting hyponatremia slowly to avoid complications such as central pontine myelinolysis. The underlying cause of SIADH should be treated if possible, such as discontinuing causative medications. Fluid restriction is typically recommended, with a daily limit of around 1000 ml for adults. In severe cases with neurological symptoms, intravenous hypertonic saline may be used. Medications like demeclocycline, which blocks ADH receptors, or ADH receptor antagonists like tolvaptan may also be considered.

It is important to monitor serum sodium levels closely during treatment, especially if using hypertonic saline, to prevent rapid correction that can lead to central pontine myelinolysis. Osmolality abnormalities can help determine the underlying cause of hyponatremia, with increased urine osmolality indicating dehydration or renal disease, and decreased urine osmolality suggesting SIADH or overhydration.

Drug-induced acute dystonic reactions are frequently seen in the Emergency Department. These reactions occur in approximately 0.5% to 1% of patients who have been administered metoclopramide or prochlorperazine. Procyclidine, an anticholinergic medication, has proven to be effective in treating drug-induced parkinsonism, akathisia, and acute dystonia. In emergency situations, a dose of 10 mg IV of procyclidine can be administered to promptly treat acute drug-induced dystonic reactions.