Acetylcholine is released from the presynaptic membrane into the cleft where it binds to the ion gated channels on the post synaptic membrane, causing them to open. This results in sodium entering into the fibre and further depolarizing it, creating an action potential.

Complications related to stapled anastomoses include bleeding, device failure, and anastomotic failure, which include stricture or leak.
Stricture: Patient discomfort, need for additional procedures
Bleeding: Hemodynamic implications, difficult intraoperative visualization
Anastomotic leak: Increase in local recurrence, decreased overall survival, sepsis, need for diverting ostomy, increased hospital cost, increased use of hospital resources, decreased quality of life.
Anastomotic bleeding is a common complication of stapled anastomoses, and it can lead to hemodynamic instability and anaemia, sometimes requiring transfusion or additional procedures. To this end, there are efforts aimed at reducing staple line haemorrhage by using buttressing techniques.

It is known that the small saphenous vein has nine to twelve valves along its course. This vein begins as a direct continuation of the lateral marginal vein posterior to the lateral malleolus. It is superficially situated but closer to its termination, perforates the deep fascia in the lower part of the popliteal fossa to end in the popliteal vein.

Liposarcoma is a cancer that arises in fat cells in deep soft tissue. Commonly it occurs inside the thigh or retroperitoneum. It usually affects middle-aged and older adults, over 40 years. Liposarcoma is the most common soft-tissue sarcoma. It is very radio resistant. Five-year survival rates vary from 100% to 56% based on histological subtype.

This case is suggestive of Dupuytren’s contracture due to palmar fibromatosis. Its incidence is higher in men over the age of 45 years, and it increases in patients with diabetes, alcoholism, or epilepsy. These nodules are benign, usually appearing as a tender nodule in the palm which becomes painless. The disease has an aggressive clinical behaviour and recurs frequently.

The tail of the pancreas is the only intraperitoneal part of the pancreas and is found contained in the splenorenal ligament of the peritoneal cavity. The splenorenal ligament is derived from the peritoneum where the wall of the general peritoneal cavity connects to the omental bursa between the spleen and the left kidney. This ligament contains the splenic vessels and the tail of the pancreas.
The gastrocolic ligament stretches from the greater curvature of the stomach to the transverse colon, connecting the two.
The gastrosplenic ligament is derived from the greater omentum and is the structure that connects the stomach to the hilum of the spleen. The gastrosplenic ligament continues from the splenic flexure of the colon to the diaphragm and acts as a support to the spleen.
The transverse colon is connected to the abdominal wall by the mesocolon ligament.
The falciform ligament on the other hand, attaches the liver to the ventral wall of the abdomen.
The hepatoduodenal ligament connects the porta hepatis of the liver to the superior part of the duodenum.

Lymphocytes and monocytes are commonly and characteristically recognised in a case of chronic inflammation.
Eosinophils and neutrophils are seen with acute inflammation.
Mast cells release histamine in early inflammation.
Basophils are seen with allergies.
Plasma cells are seen with viral infection.
Platelets are not characteristic of any type of inflammation.

The musculoskeletal nerve supplies the muscles of the anterior compartment of the arm including the coracobrachialis, biceps brachii and the greater part of the brachialis. This nerve derives its fibres from the fifth, sixth and seventh cervical nerves and arises from the lateral cord of the brachial plexus. It also provides a branch to the elbow joint.

The AV node is a conducting tissue found between the atria and the ventricles of the heart. It conducts electrical signal from the atria to the ventricles and acts a delaying mechanism preventing the atria and the ventricles from contracting at the same time. This decremental conduction prevents premature ventricular contraction in cases such as atrial fibrillation. A delay in the AV node is the reason for the PR segment seen on the ECG. In certain types of supraventricular tachycardia, a person could have two AV nodes; this will cause a loop in electrical current and uncontrollably rapid heart beat. When this electricity catches up with itself, it will dissipate and return to a normal heart rate.

Total peripheral resistance = Mean arterial pressure/Cardiac output. And the mean arterial pressure = Diastolic pressure + 1/3 (Systolic pressure – Diastolic pressure), i.e., 70 + 1/3 (130-70) = 90 mmHg. Therefore, total peripheral resistance = 90 mmHg/5 l per min = 18 mmHg × min/l.

The adductors of the fingers are the palmer interossei. They are supplied by the ulnar nerve, which is a branch of the medical cord of the brachial plexus.

Sentinel lymph node biopsy has become the gold standard for axillary staging for patients with clinically and radiologically node negative axilla. The recommended technique is the dual technique of blue dye/radioisotope and this is associated with high sentinel node identification rates (> 95 %). However, in centres where radioisotope is not available, blue dye guided four node sampling appears to be a reasonable alternative. Sentinel node biopsy was shown to be an accurate technique for axillary node staging in the ALMANAC Trial with less associated morbidity and strong health economic arguments for its use.

The tumour in this patient is small so a wide local excision should be done.
Lumpectomy or breast wide local excision is a surgical removal of a discrete portion or lump of breast tissue, usually in the treatment of a malignant tumour or breast cancer. It is considered a viable breast conservation therapy, as the amount of tissue removed is limited compared to a full-breast mastectomy, and thus may have physical and emotional advantages over more disfiguring treatment. Sometimes a lumpectomy may be used to either confirm or rule out that cancer has actually been detected. A lumpectomy is usually recommended to patients whose cancer has been detected early and who do not have enlarged tumours.

A cerebral abscess can result from direct extension of cranial infections, penetrating head trauma, haematogenous spread, or for unknown causes. An abscess forms when an area of cerebral inflammation becomes necrotic and encapsulated by glial cells and fibroblasts. Oedema around the abscess can increase the intracranial pressure. Symptoms result from increased intracranial pressure and mass effects. In a CT scan, an abscess appears as an oedematous mass with ring enhancement.

Cerebellar disease leads to intention tremors, which is absent at rest and appears at the onset of voluntary movements. In comparison, Parkinson’s tremor is present at rest. Frequency of tremor is a less reliable means to differentiate between the two as the oscillation amplitude of the tremor is not constant throughout a voluntary action.

Acute respiratory distress syndrome (ARDS) is an inflammatory process in the lungs that induces non-hydrostatic protein-rich pulmonary oedema. The immediate consequences are profound hypoxemia, decreased lung compliance, and increased intrapulmonary shunt and dead space. The clinicopathological aspects include severe inflammatory injury to the alveolar-capillary barrier, surfactant depletion, and loss of aerated lung tissue.

The most recent definition of ARDS, the Berlin definition, was proposed by a working group under the aegis of the European Society of Intensive Care Medicine. It defines ARDS by the presence within 7 days of a known clinical insult or new or worsening respiratory symptoms of a combination of acute hypoxemia (PaO2/FiO2 ≤ 300 mmHg), in a ventilated patient with a positive end-expiratory pressure (PEEP) of at least 5 cmH2O, and bilateral opacities not fully explained by heart failure or volume overload i.e. the heart pressure is norma. The Berlin definition uses the PaO2/FiO2 ratio to distinguish mild ARDS (200 < PaO2/FiO2 ≤ 300 mmHg), moderate ARDS (100 < PaO2/FiO2 ≤ 200 mmHg), and severe ARDS (PaO2/FiO2 ≤ 100 mmHg).
Most cases of ARDS in adults are associated with pulmonary sepsis (46 percent) or nonpulmonary sepsis (33 percent). Risk factors include those causing direct lung injury (e.g., pneumonia, inhalation injury, pulmonary contusion) and those causing indirect lung injury (e.g., nonpulmonary sepsis, burns, transfusion-related acute lung injury)

Most patients with ARDS need sedation, intubation, and ventilation while the underlying injury is treated. Any ventilator mode may be used, according to the Surviving Sepsis Clinical Practice Guideline and the National Heart, Lung, and Blood Institute’s ARDS Network (ARDSNet). Respiratory rate, expiratory time, positive end-expiratory pressure, and FiO2 are set following ARDSNet protocols. Settings are adjusted to maintain an oxygen saturation of 88 to 95 percent and a plateau pressure of 30 cm H2O or less to avoid barotrauma. Clinical practice guidelines recommend maintaining an arterial pH of 7.30 to 7.45, although patients in some research trials have tolerated permissive hypercapnia and a pH as low as 7.15

This patient is malnourished. Although surgery is imminent, it is best for him to be nutritionally optimised first. As he may have reduced surface area for absorption and has a localised perforation, total parenteral nutrition (TPN) is likely the best feeding modality.

The National Institute for Health and Care Excellence (NICE) has laid down guidelines for identifying patients as malnourished or at risk of malnourishment, in order to start oral, enteral, or parenteral nutrition support, alone or in combination.

Following patients are identified as malnourished:
1. BMI <18.5 kg/m2
2. Unintentional weight loss of >10% within the last 3–6 months
3. BMI <20 kg/m2 and unintentional weight loss of >5% within the last 3–6 months

Following patients are at risk of malnutrition:
1. Eaten nothing or little for >5 days and/or likely to eat little or nothing for the next 5 days or longer
2. Poor absorptive capacity and/or
3. High nutrient loss and/or
4. High metabolic rate

Considering the method of parenteral nutrition:
1. For feeding <14 days, consider feeding via a peripheral venous catheter
2. For feeding >30 days, use a tunnelled subclavian line,
continuous administration in severely unwell patients
3. If feed needed for >2 weeks, consider changing from continuous to cyclical feeding
4. Do not give >50% of daily regime to unwell patients in the first 24–48 hours
5. In surgical patients, if malnourished with unsafe swallow or a non-functional GI tract or perforation, consider perioperative parenteral feeding.

Craniopharyngiomas (also known as Rathke pouch tumours, adamantinomas or hypophyseal duct tumours) affect children mainly between the age of 5 and 10 years. It constitutes 9% of brain tumours affecting the paediatric population. These are slow-growing tumours which can also be cystic, and arise from the pituitary stalk, specifically the nests of epithelium derived from Rathke’s pouch. Histologically, this tumour shows nests of squamous epithelium which is lined on the outside by radially arranged cells. Calcium deposition is often seen with a papillary type of architecture.
ACTH-secreting pituitary adenomas are rare and mostly microadenomas. Paediatric astrocytoma’s usually occur in the posterior fossa. Although null cell adenomas can cause mass effect and give rise to the described symptoms, they are not suprasellar. Prolactinomas can also show symptoms of headache and disturbances in the visual field, however they are known to be small and slow-growing.

Alveolar ventilation = respiratory rate × (tidal volume − anatomical dead space volume). Increase in respiratory rate simply causes movement of air in the anatomical dead space, with no contribution to the alveolar ventilation. By use of a shorter snorkel, the effective anatomical dead space will decrease and will cause a maximum rise in alveolar ventilation along with doubling of tidal volume.

Answer: Instillation of warmed intra peritoneal fluid

Hypothermia describes a state in which the body’s mechanism for temperature regulation is overwhelmed in the face of a cold stressor. Hypothermia is classified as accidental or intentional, primary or secondary, and by the degree of hypothermia.
Active central rewarming is the fastest and most invasive method of rewarming. It involves use of warm IV fluids, gastric lavage and peritoneal dialysis by warm fluids. Peritoneal dialysis can be safely done with crystalloid dialysate at 40 to 42°C and it raises the body temperature by 4 to 6°C/hour.

The muscle is the subscapularis muscle which is supplied by the lower subscapular nerve.

Extradural haematoma is the most likely cause of this patient’s symptomology. The middle meningeal artery is prone to damage when the temporal side of the head is hit.

Patients who suffer head injuries should be managed according to ATLS principles and extracranial injuries should be managed alongside cranial trauma. Inadequate cardiac output compromises the CNS perfusion, irrespective of the nature of cranial injury.

An extradural haematoma is a collection of blood in the space between the skull and the dura mater. It often results from acceleration-deceleration trauma or a blow to the side of the head. The majority of extradural haematomas occur in the temporal region where skull fractures cause a rupture of the middle meningeal artery. There is often loss of consciousness following a head injury, a brief regaining of consciousness, and then loss of consciousness again—lucid interval. Other symptoms may include headache, confusion, vomiting, and an inability to move parts of the body. Diagnosis is typically by a CT scan or MRI, and treatment is generally by urgent surgery in the form of a craniotomy or burr hole.

Weakening of pulse with inhalation and strengthening with exhalation is known as pulsus paradoxus. This represents an exaggeration of the normal variation of the pulse in relation to respiration. It indicates conditions such as cardiac tamponade and lung disease. The paradox refers to the auscultation of extra cardiac beats on inspiration, as compared to the pulse. Due to a decrease in blood pressure, the radial pulse becomes impalpable along with an increase in jugular venous pressure height (Kussmaul sign). Normal systolic blood pressure variation (with respiration) is considered to be >10 mmHg. It is >100 mmHg in Pulsus paradoxus. It is also predictive of the severity of cardiac tamponade.

The short gastric arteries arise from the end of the splenic arteries and form five to seven branches. The short gastric arteries inside the gastrosplenic ligament from the left to the right, supply the greater curvature of the stomach. The hepatic artery proper runs inside the hepatoduodenal ligament. The right gastric artery and the left gastric artery are contained in the hepatogastric ligament. The caudal pancreatic artery branches off from the splenic artery and supplies the tail of the pancreas. The middle colic artery supplies the transverse colon. The splenic artery does not travel in the gastrosplenic ligament and so it would not be damaged by a tear to this ligament.

Answer: Thoracotomy in theatre

A high CVP of 13 indicates cardiac tamponade. Cardiac tamponade is a clinical syndrome caused by the accumulation of fluid in the pericardial space, resulting in reduced ventricular filling and subsequent hemodynamic compromise. The condition is a medical emergency, the complications of which include pulmonary oedema, shock, and death.
A pericardiotomy via a thoracotomy is mandatory for lifesaving cardiac decompression in acute traumatic cardiac tamponade in cases of ineffective drainage due to clot formation within the pericardial space. Wherever possible a patient needing surgery for penetrating chest trauma should be moved to an operating theatre where optimal surgical expertise and facilities are available.

Answer: Flail chest injury

Flail chest is a life-threatening medical condition that occurs when a segment of the rib cage breaks due to trauma and becomes detached from the rest of the chest wall. Two of the symptoms of flail chest are chest pain and shortness of breath.

It occurs when multiple adjacent ribs are broken in multiple places, separating a segment, so a part of the chest wall moves independently. The number of ribs that must be broken varies by differing definitions: some sources say at least two adjacent ribs are broken in at least two places, some require three or more ribs in two or more places. The flail segment moves in the opposite direction to the rest of the chest wall: because of the ambient pressure in comparison to the pressure inside the lungs, it goes in while the rest of the chest is moving out, and vice versa. This so-called paradoxical breathing is painful and increases the work involved in breathing.

Flail chest is usually accompanied by a pulmonary contusion, a bruise of the lung tissue that can interfere with blood oxygenation. Often, it is the contusion, not the flail segment, that is the main cause of respiratory problems in people with both injuries.

Surgery to fix the fractures appears to result in better outcomes.

On transmission of a loud sound into the central nervous system, an attenuation reflex occurs after a latent period of 40-80 ms. This reflex contracts the two muscles that pull malleus and stapes closer, developing a high degree of rigidity in the entire ossicular chain. This reduces the ossicular conduction of low frequency sounds to the cochlea by 30-40 decibels. In this way, the cochlea is protected from damage due to loud sounds (these are low frequency sounds) when they develop slowly.

Carpal tunnel syndrome tends to occur in women between the ages of 30-50. There are many risk factors, including diabetes, hypothyroidism, obesity, pregnancy, and repetitive wrist work. Symptoms include pain in the hand and wrist, tingling, and numbness distributed along the median nerve (the palmar side of the thumb, the index and middle fingers, and the radial half of the ring finger), which worsens at night.

The costodiaphragmatic recess is the lowest point of the pleural sac where the costal pleura becomes the diaphragmatic pleura. At the midclavicular line, this is found between ribs 6 and 8; at the paravertebral lines, between ribs 10 and 12 and between ribs 8 and 10 at the midaxillary line.
The cardiac notch: is an indentation of the heart on the left lung, located on the anterior surface of the lung.
Cupola: part of the parietal pleura that extends above the first rib.
Oblique pericardial sinus: part of the pericardial sac located posterior to the heart behind the left atrium.
Costomediastinal recess: a reflection of the pleura from the costal surface to the mediastinal surface, is on the anterior surface of the chest.
The inferior mediastinum: is the space in the chest occupied by the heart.

Fractures of the distal radius account for up to 20% of all fractures treated in the emergency department. Initial assessment includes a history of the mechanism of injury, associated injury and appropriate radiological evaluation
Most of the fractures are caused by a fall on the outstretched hand with the wrist in dorsiflexion. The form and severity of fracture of distal radius as well as the concomitant injury of disco-ligamentary structures of the wrist also depend on the position of the wrist at the moment of hitting the ground. The width of this angle influences the localization of the fracture. Pronation, supination and abduction determine the direction of the force and the compression of the carpus and different appearances of ligament injuries.
The basic principle of fracture treatment is to obtain accurate fracture reduction and then to use a method of immobilization that will maintain and hold that reduction. While the goal of treatment in fracture distal end of the radius is the restoration of normal function, the precise methods to achieve that desired outcome are controversial. Intra-articular fractures of the distal end of the radius can be difficult to treat, at times, with a traditional conservative method. A number of options for treatment are available to prevent the loss of reduction in an unstable fracture of the distal end of the radius.
One of the recent advances in the treatment of distal radius fractures is the more frequent application of open reduction and internal fixation, especially for intra-articular fractures. There are two groups of fractures for which open reduction and internal fixation is advisable.
The first group includes the two-part shear fracture (Barton fracture), which actually is a radio-carpal fracture-dislocation. Although the anatomical reduction is possible by closed means in some cases, these fractures are very unstable and difficult to control in plaster. The second group includes complex intra-articular fractures in which the articular fragments are displaced, rotated or impacted and are not amenable to reduction through limited operative exposure.

The most common congenital cyanotic heart disease and the most common cause of blue baby syndrome, Tetralogy of Fallot shows four cardiac malformations occurring together. These are ventricular septal defect (VSD), pulmonary stenosis (right ventricular outflow obstruction), overriding aorta (degree of which is variable), and right ventricular hypertrophy. The primary determinant of severity of disease is the degree of pulmonary stenosis. Tetralogy of Fallot is seen in 3-6 per 10,000 births and is responsible for 5-7% congenital heart defects, with slightly higher incidence in males. It has also been associated with chromosome 22 deletions and DiGeorge syndrome. It gives rise to right-to-left shunt leading to poor oxygenation of blood. Primary symptom is low oxygen saturation in the blood with or without cyanosis at birth of within first year of life. Affected children ay develop acute severe cyanosis or ‘tet spells’ (sudden, marked increase in cyanosis, with syncope, and may result in hypoxic brain injury and death). Other symptoms include heart murmur, failure to gain weight, poor development, clubbing, dyspnoea on exertion and polycythaemia. Chest X-ray reveals characteristic coeur-en-sabot (boot-shaped) appearance of the heart. Treatment consists of immediate care for cyanotic spells and Blalock–Taussig shunt (BT shunt) followed by corrective surgery.