Baroreceptors are sensors located in the blood vessels of all vertebrate animals. They sense the blood pressure and relay the information to the brain, so that a proper blood pressure can be maintained. Acute dehydration results in decreased plasma volume and increased plasma osmolarity, since more water than salt is lost in sweat. The decrease in plasma volume leads to an inhibition of the baroreceptors and a lower firing rate. The increase in plasma osmolarity leads to increased ADH secretion and high plasma ADH levels, which increases water permeability of collecting duct cells. Therefore more water is reabsorbed by the kidneys and renal water excretion is low.

At rest, the brain receives 15% cardiac output, muscles 15%, gastrointestinal tract 30% and kidneys receive 20%. However, if normalised by weight, the largest specific blood flow is received by the kidneys at rest (400 ml/min x 100g), making them highly vulnerable in the case of a haemorrhagic shock.

Answer: Obtain intravenous access, administer fluids and antibiotics.

Intussusception is a condition in which one segment of intestine telescopes inside of another, causing an intestinal obstruction (blockage). Although intussusception can occur anywhere in the gastrointestinal tract, it usually occurs at the junction of the small and large intestines. The obstruction can cause swelling and inflammation that can lead to intestinal injury. The patient with intussusception is usually an infant, often one who has had an upper respiratory infection, who presents with the following symptoms:

Vomiting: Initially, vomiting is nonbilious and reflexive, but when the intestinal obstruction occurs, vomiting becomes bilious

Abdominal pain: Pain in intussusception is colicky, severe, and intermittent

Passage of blood and mucus: Parents report the passage of stools, by affected children, that look like currant jelly; this is a mixture of mucus, sloughed mucosa, and shed blood; diarrhoea can also be an early sign of intussusception

Lethargy: This can be the sole presenting symptom of intussusception, which makes the condition’s diagnosis challenging

Palpable abdominal mass

Diagnosis:
Ultrasonography: Hallmarks of ultrasonography include the target and pseudo kidney signs.

For all children, start intravenous fluid resuscitation and nasogastric decompression as soon as possible.

In adults 50% of the cases of brain death follow severe head injury, 30% are due to subarachnoid haemorrhage and 20% are due to a severe hypoxic-ischaemic event. Thus supra-tentorial catastrophes lead to pressure effect which cause the irretrievable death of the brain-stem.

The Criteria for Diagnosis of Brain-Stem Death

All the pre-conditions must be satisfied and
there should be demonstrably no pharmacological or
metabolic reason for the coma before formally testing the
integrity of the brain-stem reflexes.

Pre Conditions
1. The patient is comatose and mechanically ventilated
for apnoea.
2. The diagnosis of structural brain damage has been
established or the immediate cause of coma is known.
3. A period of observation is essential.

Exclusions
1. Drugs are not the cause of coma e.g. barbiturates.
Neuromuscular blockade has been demonstrably reversed.
2. Hypothermia does not exist.
3. There is no endocrine or metabolic disturbance.

Testing for Brain-Stem Death
Reflexes involving brain-stem function.
1. No pupillary response to light.
2. No corneal reflex.
3. No vestibulo ocular reflex (Caloric test).
4. Doll’s eye reflex
5. No motor response to pain – in the Vth nerve distribution.
6. No gag reflex in response to suction through endotracheal tube or tracheostomy.
7. Apnoea persists despite a rise in PaCO2 to greater than 50 mmHg (6.6kPa) against a background of a normal PaO2.

Diagnosis is to be made by two doctors who have been registered for more than five years and are competent in the procedure. At least one should be a consultant. Testing should be undertaken by the doctors together and must always be performed completely and successfully on two occasions in total.

In atrial fibrillation, the abnormal atrial contraction can cause blood to stagnate in the left atrium and form a thrombus, which may then embolize. The patient’s history of AF suggest an embolic disease, which lead to his death.

The dorsal primary ramus of the spinal nerve C2 is the greater occipital nerve which provides cutaneous innervation to the skin of the back of the head. The ventral primary ramus gives off the great auricular nerve, the lesser occipital nerve and the ansa cervicalis.

Thoracic trauma accounts for > 25% of all traumatic injuries and is a leading cause of death in all age groups. The majority of thoracic trauma patients require only conservative management (e.g. analgesia, simple chest drainage). However, a subset of these patients will show signs of deterioration in the emergency department, especially with penetrating injuries. Such patients may require an emergency thoracotomy for rapid access to the thoracic cavity so that pericardial tamponade can be released and haemorrhage controlled. Furthermore, in severe thoracic trauma cases, specific injuries are difficult to confidently rule out or identify, even if they can be anticipated. Therefore, it is recommended to use an approach that provides the most rapid access to all vital chest organs for assessment and control.
Clamshell thoracotomy (also known as bilateral anterolateral thoracotomy) or hemi-clamshell (longitudinal sternotomy and anterolateral thoracotomy) are techniques used to provide complete exposure of the thoracic cavity (heart, mediastinum and lungs). Studies have demonstrated that it is easier to control the cardiac wound using this approach compared to the standard left anterolateral thoracotomy, as it gives wider exposure for all injuries, which are then easier to control surgically through the larger incision.
Contraindications:
Absolute:
– Traumatic cardiac arrest where the underlying pathology is so severe as to render the procedure futile (e.g. severe traumatic brain injury)
Relative:
Blunt cardiac injury with no signs of life or organised cardiac rhythm

This is likely a case of epididymo-orchitis which usually occurs due to infection with gonorrhoea or chlamydia in this age group (<35 years). Epididymo-orchitis is an acute inflammation of the epididymis and often involves the testis. It is usually caused by bacterial infection which spreads from the urethra or bladder. Amiodarone is a recognised non-infective cause of epididymitis, which resolves on stopping the drug. On examination, tenderness is usually confined to the epididymis, which may facilitate differentiating it from torsion where pain usually affects the entire testis.

Invasion is suggestive of malignancy and an even better option would have been metastasis. Pleomorphism is found in both benign and malignant neoplasms along with atypia and anaplasia. A height nuclear/cytoplasmic ratio is suggestive of malignancy but not the best indicator. Malignant tumours are aggressive and growth rapidly. Necrosis can be seen in benign tumours if they deplete their blood supply.

Liddle’s syndrome,  is an autosomal dominant disorder, that is characterized by early, and frequently severe, high blood pressure associated with low plasma renin activity, metabolic alkalosis, low blood potassium, and normal to low levels of aldosterone. Liddle syndrome involves abnormal kidney function, with excess reabsorption of sodium and loss of potassium from the renal tubule. Bartter Syndrome also presents with hypokalaemia, however blood pressure of these patients is usually low or normal.

Upper gastrointestinal (GI) bleeding is usually defined by a bleeding source proximal to the ligament of Treitz although some may also include a bleeding source in the proximal jejunum. Upper GI bleeding emergencies are characterized by hematemesis, melena, haematochezia (if the bleeding is massive and brisk) and evidence of hemodynamic compromise such as dizziness, syncope episodes and shock. The most commonly used endoscopic haemostatic interventions include epinephrine (adrenaline) injection, thermal coagulation and endoscopic clipping at the ulcer site to constrict, compress and/or destroy the bleeding vessel. Injection of 30 mL diluted epinephrine (1:10 000) can effectively prevent recurrent bleeding with a low rate of complications. The optimal injection volume of epinephrine for endoscopic treatment of an actively bleeding ulcer (spurting or oozing) is 30 mL.

Adductor canal compression syndrome most commonly presents in young males, and it is important to differentiate it from acute limb ischaemia on exertion. Of the listed options, popliteal fossa entrapment is the main differential diagnosis. However, the popliteal pulse disappears when the knee is fully extended in popliteal fossa entrapment.

Adductor canal compression syndrome is caused by compression of the femoral artery by the musculotendinous band of adductor magnus muscle. The treatment consists of division of the abnormal band and restoration of the arterial circulation.

Cryptosporidium infection occurs through the faecal-oral route of transmission. It usually lasts for 5–7 days. In immunocompetent patients it is self-limiting (nitazoxanide may be used to shorten the duration). In immunocompromised patients: Antiretroviral therapy to elevate the CD4 cell count/restore the immune system is essential prior to eradication with antiparasitic drugs. Diarrhoea is the main disease. The cysts are typically identified on stool microscopy.

Hypercalcaemia with hypophosphatemia indicates parathyroid disorder and adenomas are more common than hyperplasia. In this young age group, metastatic disease is unlikely. Solitary adenomas are responsible for 80-85% cases of primary hyperparathyroidism. 10-15% cases are due to parathyroid hyperplasia and carcinomas account for 2-3% cases. Symptoms include bone pain (bones), nephrolithiasis (stones), muscular aches, peptic ulcer disease, pancreatitis (groans), depression (moans), anxiety and other mental disturbances.

The median nerve provides cutaneous innervation to the skin of the palmar radial three and a half fingers. Also the site of injury indicates that the medial nerve may have been injured as it passes into the hand by crossing over the anterior wrist.

The definitive treatment for appendicitis is appendectomy. An appendectomy, also spelled appendicectomy, is a surgical operation in which the vermiform appendix is removed. Appendectomy is normally performed as an urgent or emergency procedure to treat acute appendicitis.

Appendectomy may be performed laparoscopically (as minimally invasive surgery) or as an open operation. Laparoscopy is often used if the diagnosis is in doubt, or in order to leave a less visible surgical scar.
The classic history of anorexia and vague periumbilical pain, followed by migration of pain to the right lower quadrant (RLQ) and onset of fever and vomiting, is observed in fewer than 60% of patients. Children with appendicitis do not localize in the same way as adults and often the diagnosis is difficult and all too often made late. If the appendix perforates, an interval of pain relief is followed by development of generalized abdominal pain and peritonitis.

Laboratory findings may increase suspicion of appendicitis but are not diagnostic. The minimum laboratory workup for a patient with possible appendicitis includes a white blood cell (WBC) count with differential and urinalysis. Liver function tests and amylase and lipase assessments are helpful when the aetiology is unclear. Baseline blood urea nitrogen and creatinine are needed prior to intravenous contrast CT scanning. The WBC count becomes elevated in approximately 70-90% of patients with acute appendicitis.

Infection by Ascaris lumbricoides usually occurs after individuals have visited places like sub-Saharan Africa or the Far East. Unlike Ancylostoma duodenale infection, there is usually an evidence of both worms and eggs in the stool. The absence of pruritus makes Enterobius vermicularis less likely.

Ascariasis occurs due to infection with a roundworm Ascaris lumbricoides. It begins in the gut following ingestion, then penetrates the duodenal wall to migrate to the lungs, is coughed up and swallowed, and the cycle begins again.

Diagnosis is made by identification of worms or eggs within the faeces. Treatment is with mebendazole.

Polycythaemia is a condition that results in an increase in the total number of red blood cells (RBCs) in the blood. It can be due to myeloproliferative syndrome or due to chronically low oxygen levels or rarely malignancy. In primary polycythaemia/polycythaemia vera the increase is due to an abnormality in the bone marrow, resulting in increases RBCs, white blood cells (WBCs) and platelets. In secondary polycythaemia the increase occurs due to high levels of erythropoietin either artificially or naturally. The increase is about 6-8 million/cm3 of blood. A type of secondary polycythaemia is physiological polycythaemia where people living in high altitudes who are exposed to hypoxic conditions produce more erythropoietin as a compensatory mechanism for thin oxygen and low oxygen partial pressure.

Pepsinogen is the inactive precursor of pepsin. Once secreted, it comes in contact with hydrochloric acid and pepsin, previously formed, and undergoes cleavage to form active pepsin.

Aortic transection was the underlying cause of death in this patient.

Aortic transection, or traumatic aortic rupture, is typically the result of a blunt aortic injury in the context of rapid deceleration. This condition is commonly fatal as blood in the aorta is under great pressure and can quickly escape the vessel through a tear, resulting in rapid haemorrhagic shock and death. A temporary haematoma may prevent the immediate death. Injury to the aorta during a sudden deceleration commonly originates near the terminal section of the aortic arch, also known as the isthmus. This portion lies just distal to the take-off of the left subclavian artery at the intersection of the mobile and fixed portions of the aorta. As many as 80% of the patients with aortic transection die at the scene before reaching a trauma centre for treatment.

A widened mediastinum may be seen on the X-ray of a person with aortic rupture.

Other types of thoracic trauma include:
1. Tension pneumothorax and pneumothorax
2. Haemothorax
3. Flail chest
4. Cardiac tamponade
5. Blunt cardiac injury
6. Pulmonary contusion
7. Diaphragm disruption
8. Mediastinal traversing wounds

Answer: Perthes disease

Perthes’ disease is a condition affecting the hip joint in children. It is rare (1 in 9,000 children are affected) and we do not clearly understand why it occurs.

Part or all of the femoral head (top of the thigh bone: the ball part of the ball-and-socket hip joint) loses its blood supply and may become misshapen. This may lead to arthritis of the hip in later years.

The earliest sign of Legg-Calvé-Perthes disease (LCPD) is an intermittent limp (abductor lurch), especially after exertion, with mild or intermittent pain in the anterior part of the thigh. LCPD is the most common cause of a limp in the 4- to 10-year-old age group, and the classic presentation has been described as a painless limp.
The patient may present with limited range of motion of the affected extremity. The most common symptom is persistent pain.

Hip pain may develop and is a result of necrosis of the involved bone. This pain may be referred to the medial aspect of the ipsilateral knee or to the lateral thigh. The quadriceps muscles and adjacent thigh soft tissues may atrophy, and the hip may develop adduction flexion contracture. The patient may have an antalgic gait with limited hip motion.
Early radiographic changes may reveal only a nonspecific effusion of the joint associated with slight widening of the joint space, metaphyseal demineralization (decreased bone density around the joint), and periarticular swelling (bulging capsule). This is the acute phase, and it may last 1-2 weeks. Decreasing bone density in and around the joint is noted after a few weeks. Eventually, the disease may progress to collapse of the femoral head, increase in the width of the neck, and demineralization of the femoral head. The final shape of this area depends on the extent of necrosis and the degree of collapse.

Answer: Undertake an open inguinal herniotomy

Inguinal hernia is a type of ventral hernia that occurs when an intra-abdominal structure, such as bowel or omentum, protrudes through a defect in the abdominal wall. Inguinal hernias do not spontaneously heal and must be surgically repaired because of the ever-present risk of incarceration. Generally, a surgical consultation should be made at the time of diagnosis, and repair (on an elective basis) should be performed very soon after the diagnosis is confirmed.

The infant or child with an inguinal hernia generally presents with an obvious bulge at the internal or external ring or within the scrotum. The parents typically provide the history of a visible swelling or bulge, commonly intermittent, in the inguinoscrotal region in boys and inguinolabial region in girls. The swelling may or may not be associated with any pain or discomfort.

Open herniotomy is its standard treatment against which all alternative modalities of treatment are evaluated. It is credited with being easy to perform, having a high success rate, and low rate of complications.
The use of prosthetic mesh in these patients is rare, however not uncalled for. Laparoscopic inguinal herniotomy is significantly associated with longer operative time for unilateral cases and a reduction in metachronous hernia development when compared to open inguinal herniotomy. There was a trend towards higher recurrence rate for laparoscopic repairs and shorter operative time for bilateral cases. A well conducted randomized controlled trial is warranted to compare both approaches.

PR interval extends from the beginning of the P-wave until the beginning of the QRS complex. The normal duration of the PR interval is 0.12-0.20 s. It can be prolonged in first degree heart block, and reduced in Wolff-Parkinson-White syndrome.

Gallstone ileus accounts for 1-4% of all small bowel obstructions, predominantly affecting elderly females. This entity is associated with a mortality approaching 20% due to the associated comorbidities that are often present.
Principles of treatment include stone removal via enterotomy through a site proximal to that of the obstruction.
Decompression using a sucking apparatus with many large openings, inserted through an enterotomy, is a fast and suitable method. The danger of wound infection can be considerably reduced by careful technique and by antibiotics. Nevertheless, open suction should be used only when the peritoneal cavity is already infected, or when closed decompression by retrograde stripping into the stomach is not possible.

Patients with bowel obstruction who have either been vomiting or at high risk of regurgitation of gastric contents on the induction of anaesthesia. Aspiration of stomach contents from the pharynx is prevented by sealing off the airway. This is achieved by passing a cuffed endotracheal tube and the patient is in considerable danger from the moment consciousness is lost until this has been done. All methods of inducing general anaesthesia in intestinal obstruction rely on the speedy insertion of such a tube, and the anaesthetist must ensure pre-operatively that the patient can be intubated.
Cricoid pressure. As soon as the patient loses consciousness, an assistant exerts firm backwards pressure on the cricoid cartilage, obliterating the oesophageal lumen. This prevents regurgitated fluids from entering the pharynx from below, it prevents anaesthetic gases from entering (and distending) the stomach from above, and it facilitates intubation by pushing the larynx posteriorly.

Pacinian corpuscles are a type of mechanoreceptor, sensitive to deep pressure, touch and high-frequency vibration. The Pacinian corpuscles are ovoid and about 1 mm long. In the centre of the corpuscle is the inner bulb, which is a fluid-filled cavity with a single afferent unmyelinated nerve ending. Any deformation in the corpuscle causes the generation of action potentials by opening of pressure-sensitive sodium ion channels in the axon membrane. This allows influx of sodium ions, creating a receptor potential (independent of potassium channels).

The patient’s clinical manifestations suggests an injury to the maxillary and mandibular nerves. The maxillary branch (V2) of the trigeminal nerve (CN V) passes through and exits the skull via the pterygopalatine fossa and the foramen rotundum. At the base of the skull the foramen ovale (Latin: oval window) is one of the larger of the several holes (the foramina) that transmit nerves through the skull. The foramen ovale is situated in the posterior part of the sphenoid bone, posterolateral to the foramen rotundum. The following structures pass through foramen ovale: mandibular nerve, motor root of the trigeminal nerve, accessory meningeal artery (small meningeal or paradural branch, sometimes derived from the middle meningeal artery), lesser petrosal nerve, a branch of the glossopharyngeal nerve and
an emissary vein connecting the cavernous sinus with the pterygoid plexus of veins. Occasionally it will also carry the anterior trunk of the middle meningeal vein.

Buspirone is an anxiolytic agent and a serotonin-receptor agonist that belongs to the azaspirodecanedione class of compounds. It shows no potential for addiction compared with other drugs commonly prescribed for anxiety, especially the benzodiazepines. The development of tolerance has not been noted. It is primarily used to treat generalized anxiety disorders. It is also commonly used to augment antidepressants in the treatment of major depressive disorder.

Linezolid is a synthetic antibiotic used for the treatment of infections caused by multiresistant bacteria, including streptococci and methicillin-resistant Staphylococcus aureus (MRSA). Linezolid is effective against Gram-positive pathogens, notably Enterococcus faecium, S. aureus, Streptococcus agalactiae, Streptococcus pneumoniae and Streptococcus pyogenes. It has almost no effect on Gram-negative bacteria and is only bacteriostatic against most enterococci.

Epidural hematoma (EDH) is a traumatic accumulation of blood between the inner table of the skull and the stripped-off dural membrane. EDH results from a traumatic head injury, usually with an associated skull fracture and arterial laceration. The inciting event often is a focused blow to the head, such as that produced by a hammer or baseball bat. In 85-95% of patients, this type of trauma results in an overlying fracture of the skull. Blood vessels in close proximity to the fracture are the sources of the haemorrhage in the formation of an epidural hematoma. Because the underlying brain has usually been minimally injured, prognosis is excellent if treated aggressively. Outcome from surgical decompression and repair is related directly to patient’s preoperative neurologic condition.