High-probability ECG features of MI are the following:
ST-segment elevation greater than 1 mm in two anatomically contiguous leads
The presence of new Q waves

Intermediate-probability ECG features of MI are the following:
ST-segment depression
T-wave inversion
Other nonspecific ST-T wave abnormalities
Low-probability ECG features of MI are normal ECG findings. However, normal or nonspecific findings on ECGs do not exclude the possibility of MI.

Special attention should be made if there is diffuse ST depression in the precordial and extremity leads associated with more than 1 mm ST elevation in lead aVR, as this may indicate stenosis of the left main coronary artery or the proximal section of the left anterior descending coronary artery.

Localization of the involved myocardium based on the distribution of ECG abnormalities in MI is as follows:
– Inferior wall – II, III, aVF
– Lateral wall – I, aVL, V4 through V6
– Anteroseptal – V1 through V3
– Anterolateral – V1 through V6
– Right ventricular – RV4, RV5
– Posterior wall – R/S ratio greater than 1 in V1 and V2, and – T-wave changes in V1, V8, and V9
– True posterior-wall MIs may cause precordial ST depressions, inverted and hyperacute T waves, or both. ST-segment elevation and upright hyperacute T waves may be evident with the use of right-sided chest leads.

Hyperacute (symmetrical and, often, but not necessarily pointed) T waves are frequently an early sign of MI at any locus.
The appearance of abnormalities in a large number of ECG leads often indicates extensive injury or concomitant pericarditis.
The characteristic ECG changes may be seen in conditions other than acute MI. For example, patients with previous MI and left ventricular aneurysm may have persistent ST elevations resulting from dyskinetic wall motion, rather than from acute myocardial injury. ST-segment changes may also be the result of misplaced precordial leads, early repolarization abnormalities, hypothermia (elevated J point or Osborne waves), or hypothyroidism.
False Q waves may be seen in septal leads in hypertrophic cardiomyopathy (HCM). They may also result from cardiac rotation.
Substantial T-wave inversion may be seen in left ventricular hypertrophy with secondary repolarization changes.
The QT segment may be prolonged because of ischemia or electrolyte disturbances.
Saddleback ST-segment elevation (Brugada epsilon waves) may be seen in leads V1-V3 in patients with a congenital predisposition to life-threatening arrhythmias. This elevation may be confused with that observed in acute anterior MI.
Diffuse brain injuries and haemorrhagic stroke may also trigger changes in T waves, which are usually widespread and global, involving all leads.
Convex ST-segment elevation with upright or inverted T waves is generally indicative of MI in the appropriate clinical setting. ST depression and T-wave changes may also indicate the evolution of NSTEMI.
Patients with a permanent pacemaker may confound recognition of STEMI by 12-lead ECG due to the presence of paced ventricular contractions.
To summarize, non-ischemic causes of ST-segment elevation include left ventricular hypertrophy, pericarditis, ventricular-paced rhythms, hypothermia, hyperkalaemia and other electrolyte imbalances, and left ventricular aneurysm.

The rectus abdominis muscle is supplied by the superior epigastric artery which is a branch of the internal thoracic artery. If the internal thoracic artery is thus ligated, blood would no longer flow to it. However, the superior epigastric artery communicates with the inferior epigastric artery (a branch of the external iliac artery). This means that blood could flow from the external iliac, to the inferior epigastric, to the superior epigastric to the rectus abdominis.
The superficial circumflex iliac artery and the superficial epigastric are two superficial branches of the femoral artery and do not supply the deep branches of the abdomen.
The deep circumflex iliac artery travels along the iliac crest on the inner surface of the abdominal wall; being too lateral it doesn’t supply blood to the rectus abdominis.
The distal portions of the umbilical arteries are obliterated in adults to form the medial umbilical folds.

Pulmonary embolism is caused by the sudden blockage of a major lung blood vessel, usually by a blood clot. Symptoms include sudden sharp chest pain, cough, dyspnoea, palpitations, tachycardia or loss of consciousness. Risk factors for developing pulmonary embolism include long periods of inactivity, surgery, trauma, pregnancy, oral contraceptives, oestrogen replacement, malignancies and venous stasis.

The ischial spine is always palpated through the walls of the vagina when performing a transvaginal pudendal nerve block and can easily be palpated on the lateral wall of the vagina.

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.

The paired sublingual glands are major salivary glands in the mouth. They are the smallest, most diffuse, and the only unencapsulated major salivary glands. They provide only 3-5% of the total salivary volume. The gland receives its blood supply from the sublingual and submental arteries. The sublingual artery is a branch of the lingual artery, thus damage to the lingual artery will decrease the blood flow to the sublingual gland.

Repair of an inguinal hernia under local anaesthesia has a short operative time, and patients are usually ambulant immediately after. Furthermore, the family history of this patient is unlikely to be significant and therefore, he is at a very low risk of developing a pulmonary embolism (PE).

Deep vein thrombosis (DVT) may develop insidiously in many surgical patients. If left untreated, it may progress to PE. The following surgical patients are at increased risk of developing DVT:

1. Surgery greater than 90 minutes at any site or greater than 60 minutes if the procedure involves lower limbs or pelvis
2. Acute admissions with inflammatory process involving the abdominal cavity
3. Expected significant reduction in mobility
4. Age over 60 years
5. Known malignancy
6. Thrombophilia
7. Previous thrombosis
8. BMI >30 kg/m2
9. Taking hormone replacement therapy or contraceptive pills
10. Varicose veins with phlebitis

Thromboprophylaxis can be mechanical or therapeutic. The former includes:
1. Early ambulation after surgery: cheap and effective
2. Compression stockings (contraindicated in peripheral arterial disease)
3. Intermittent pneumatic compression devices
4. Foot impulse devices

Therapeutic agents for thromboprophylaxis are:
1. Low-molecular-weight heparin (LMWH)
2. Unfractionated heparin
3. Dabigatran

Making up 4-5% of total body weight, the skin receives approximately 2% of cardiac output.

E erythropoietin (EPO) is a hormone that is released by the kidney. It is responsible for the regulation of red blood cell production in the body. It can be made using recombinant technology and is used in the treatment of anaemia of chronic renal failure and in patients under going chemotherapy

Answer: It may result in metabolic complications such a refeeding syndrome, resulting in hyperkalaemia, hypermagnesemia, and hyperphosphatemia.

Refeeding syndrome can be defined as the potentially fatal shifts in fluids and electrolytes that may occur in malnourished patients receiving artificial refeeding (whether enterally or parenterally. These shifts result from hormonal and metabolic changes and may cause serious clinical complications. The hallmark biochemical feature of refeeding syndrome is hypophosphatemia. However, the syndrome is complex and may also feature abnormal sodium and fluid balance; changes in glucose, protein, and fat metabolism; thiamine deficiency; hypokalaemia; and hypomagnesaemia.
During refeeding, glycaemia leads to increased insulin and decreased secretion of glucagon. Insulin stimulates glycogen, fat, and protein synthesis. This process requires minerals such as phosphate and magnesium and cofactors such as thiamine. Insulin stimulates the absorption of potassium into the cells through the sodium-potassium ATPase symporter, which also transports glucose into the cells. Magnesium and phosphate are also taken up into the cells. Water follows by osmosis. These processes result in a decrease in the serum levels of phosphate, potassium, and magnesium, all of which are already depleted. The clinical features of the refeeding syndrome occur as a result of the functional deficits of these electrolytes and the rapid change in basal metabolic rate.

The intragastric balloon aids weight loss by slowing the rate at which food enters the stomach and by stimulating gastric stretch receptors. But lifestyle changes, including behaviour modification, exercise and a healthy diet, are crucial for maintaining weight loss once the device is removed. Intragastric balloon is really only suitable as a bridge to a more definitive surgical solution and is associated with a high failure rates and complications.

Gastric banding: band applied to upper stomach which can be inflated or deflated with normal saline. This affects satiety. Over a 5 year period complications requiring further surgery occur in up to 15% cases.

Roux-en-Y gastric bypass: a gastric pouch is formed and connected to the jejunum. Patients achieve greater and more long-term weight loss than gastric banding.

Sleeve gastrectomy: body and fundus resected to leave a small section of stomach

Transplantation is a process by which cells, tissues, or organs (a graft) from the donor are transplanted into a host (or recipient). The immune system’s ability to recognize and respond to foreign antigens bring challenges to transplantation.
Type IV hypersensitivity is characterized by cell-mediated response rather than antibodies as in other types of hypersensitivity reactions. Specifically, the T lymphocytes are involved in the development of the sensitivity, hence called cell-mediated hypersensitivity.
After exposure to antigens, through a series of biochemical events, the T-cells will be activated. By releasing some chemicals, the T-cells activate other white blood cells to mount an immune response.
Rejection of transplant occurs months to years later. In chronic rejection, there is intimal fibrosis with vascular thickening, leading to ischemic changes. Mononuclear infiltrates with prominent plasma cells are present.

The sternal angle is an important part where the second costal cartilage attaches to the sternum. Finding the sternal angle will help in finding the second costal cartilage and intercostal space.

Achalasia is an oesophageal motility disorder where inappropriate contractions in the oesophagus lead to reduced peristalsis and failure of the lower oesophageal sphincter to relax properly in response to swallowing. Classical triad of symptoms include dysphagia to fluids followed by solids, chest pain and regurgitation of undigested food. Other symptoms include belching, hiccups, weight loss and cough. Diagnosis is by:
– X-ray with a barium swallow or oesophagography : narrowing at the gastroesophageal junction (‘bird/parrot beak’ or ‘rat tail’ appearance) and various degrees of mega-oesophagus (oesophageal dilatation) as the oesophagus is gradually stretched by retained food. Effectiveness of treatment can be measured with a 5-minute timed barium swallow.
– Manometry – probe measures the pressure waves in different parts of oesophagus and stomach while swallowing.
– Endoscopy
– CT scan to exclude other causes like malignancy
– Pathological examination showing defect in the nerves which control oesophageal motility (myenteric plexus).
In Chagas disease, there is destruction of ganglion cells by Trypanosoma cruzi.

The safest spinal level for conducting a lumbar puncture, is at the level of the fourth lumbar vertebra. The anatomical landmark used to locate the fourth lumbar vertebra (L4), is the iliac crest. The needle can safely be inserted either above or below L4. The conus medullaris is at the level of the border of L1 and L2 so L4 is safely distant from it.

The beginning of ventricular systole corresponds to the beginning of the QRS complex in the ECG. The beginning of the ventricular systole also corresponds to the closure of the atrioventricular valves, causing the first heart sound (S1). S2, the second heart sound is due to closure of the aortic and pulmonary valves at the end of ventricular systole.

The saphenous opening is an oval opening in the fascia lata. It is covered by the cribriform fascia and It is so called because it is perforated by the great saphenous vein and by numerous blood and lymphatic vessels and the superficial external pudendal artery pierces it.

Open haemorrhoidectomy is traditionally viewed as a painful procedure. Most operations are performed under general or regional anaesthesia. Following excisional haemorrhoidectomy, severe pain is not unusual, a well placed caudal anaesthetic will counter this. A pudendal nerve block is an alternative but is less effective than a caudal.

Fat is mainly transported in the body as free fatty acids. Once out of the adipose cell, the free fatty acids get ionized and combine with albumin.

At the base of the skull the foramen ovale is one of the larger of the several holes that transmit nerves through the skull. The following structures pass through foramen ovale: mandibular nerve, motor root of the trigeminal nerve, accessory meningeal artery, lesser petrosal nerve, a branch of the glossopharyngeal nerve, emissary vein connecting the cavernous sinus with the pterygoid plexus of veins and occasionally the anterior trunk of the middle meningeal vein.

Subtotal colectomy is resection of the entire right, transverse, left and part of the sigmoid colon. The rectal stump is closed and an end ileostomy fashioned in the right iliac fossa.

The first branches off spinal nerves are called the dorsal and ventral rami. The dorsal rami mediate sensation of the skin over the back and motor supply to the true muscles of the back whilst the ventral rami gives sensation to the skin over the limbs and the skin that is over the ventral side of the trunk. It also gives motor supply to the skeletal muscles of the neck, the trunk and extremities. Hence, itchiness of the part of the skin that is over the spine of the scapula would be mediated by the primary ramus of C7. Accessory nerve doesn’t have any sensory innervation.

Breast abscess occur commonly in lactating mothers in the postpartum period due to cracking of the nipple. It is commonly caused due to Staphylococcus aureus infection. Fat necrosis usually results from trauma wherein an ill-defined mass is formed. Ductal carcinomas are malignant masses which are not tender usually, and rare in the young age group. Plasma cell mastitis affect women in an older age group. Sclerosing adenosis is a type of fibrocystic disease which can lead to a tender, cystic mass but no fissuring or cracks are seen in the nipple. Fibroadenoma and lipomas are non-tender, well-defined masses.

Rapid eye movement (REM) sleep is also known as paradoxical sleep, as the summed activity of the brain’s neurons is quite similar to that during waking hours. Characterised by rapid movements of the eyes, most of the vividly recalled dreams occur during this stage of sleep. The total time of REM sleep for an adult is about 90–120 min per night.
Certain neurones in the brainstem, known as REM sleep-on cells, which are located in the pontine tegmentum, are particularly active during REM sleep and are probably responsible for its occurrence. The eye movements associated with REM are generated by the pontine nucleus with projections to the superior colliculus and are associated with PGO (pons, geniculate, occipital) waves.

The hoarseness of voice implies vocal cord paralysis denoting the spread of malignancy which is a contraindication to surgery.

Summary of Guidelines on the selection of patients with lung cancer for surgery (Related to this case)

PART I: FITNESS FOR SURGERY
Age:
1. Perioperative morbidity increases with advancing age. Elderly patients undergoing lung resection are more likely to require intensive perioperative support. Preoperatively, a careful assessment of co-morbidity needs to be made.
2. Surgery for clinically stage I and II disease can be as effective in patients over 70 years as in younger patients. Such patients should be considered for surgical treatment regardless of age.
3. Age over 80 alone is not a contraindication to lobectomy or wedge resection for clinical stage I disease.
4. Pneumonectomy is associated with higher mortality risk in the elderly. Age should be a factor in deciding suitability for pneumonectomy.

Pulmonary function:
There should be a formal liaison in borderline cases between the referring chest physician and the thoracic surgical team.
2.No further respiratory function tests are required for a lobectomy if the post-bronchodilator FEV1 is >1.5 litres and for a pneumonectomy, if the post-bronchodilator FEV1 is >2.0 litres, provided that there is no evidence of interstitial lung disease or unexpected disability due to shortness of breath.
STEP 1
3.All patients not clearly operable on the basis of spirometry should have: (a) full pulmonary function tests including estimation of transfer factor (TLCO); (b) measurement of oxygen saturation on air at rest; and (c) a quantitative isotope perfusion scan if a pneumonectomy is being considered.
4.These data should be used to calculate estimated postoperative FEV1 expressed as % predicted and the estimated postoperative TLCO expressed as % predicted, using either the lung scan for pneumonectomy or an anatomical equation for lobectomy, taking account of whether the segments to be removed are ventilated or obstructed.
STEP 2
5.(a) Estimated postoperative FEV1 >40% predicted and estimated postoperative TLCO >40% predicted and oxygen saturation (SaO 2) >90% on air: average risk.
(b)Estimated postoperative FEV1 <40% predicted and estimated postoperative TLCO <40% predicted: high risk.
(c)All other combinations: consider exercise testing.
6.Patients for whom the risk of resection is still unclear after step 2 tests should be referred for exercise testing.
STEP 3
7.(a) The best distance on two shuttle walk tests of <25 shuttles (250 m) or desaturation during the test of more than 4% SaO 2 indicates a patient is a high risk for surgery.
(b)Other patients should be referred for a formal cardiopulmonary exercise test. For cardiopulmonary exercise testing peak oxygen consumption (V˙O 2peak) of more than 15 ml/kg/min indicates that a patient is an average risk for surgery.
(c)A V˙O 2peak of <15 ml/kg/min indicates that a patient is a high risk for surgery. PART II: OPERABILITY
Diagnosis and staging
1.All patients being considered for surgery should have a plain chest radiograph and a computed tomographic (CT) scan of the thorax including the liver and adrenal glands.
2.Confirmatory diagnostic percutaneous needle biopsy in patients presenting with peripheral lesions is not mandatory in patients who are otherwise fit, particularly if there are previous chest radiographs showing no evidence of a lesion.
3.Patients with mediastinal nodes greater than 1 cm in short-axis diameter on the CT scan should undergo biopsy by staging mediastinoscopy, anterior mediastinotomy, or needle biopsy as appropriate.
Operability and adjuvant therapy
1.The proportion of patients found to be inoperable at operation should be 5–10%.
2.Patients with stage I (cT1N0 and cT2N0) and stage II (cT1N1, cT2N1 and cT3N0) tumours should be considered operable.
3.Patients with stage I tumours have a high chance and those with stage II tumours a reasonable chance of being cured by surgery alone.
4.Patients who are known preoperatively to have stage IIIA (cT3N1 and cT1–3N2) tumours have a low chance of being cured by surgery alone but might be considered operable in the context of a trial of surgery and adjuvant chemotherapy.
5.Participation in prospective trials of multimodality treatment for locally advanced disease is strongly recommended.
6.Some small individual studies indicate a place for surgery in T4N0 and T4N1 tumours within stage IIIB, few long term data are available. Generally, stage IIIB tumours with node involvement and stage IV tumours should be considered inoperable.
7.There is no place for postoperative radiotherapy following complete primary tumour resection.

The pancreas is divided into five parts; the head, body, neck, tail, and the uncinate process. Of the five parts, tumours located at the head of the pancreas in most instances cause obstruction of the common bile duct more often than tumours in the other parts of the pancreas. This is because the common bile duct passes through the head of the pancreas from the gallbladder and the liver (it is formed where the cystic and the hepatic bile duct join) to empty bile into the duodenum. This biliary obstruction leads to accumulation of bile in the liver and a consequent bilirubinaemia (raised levels of blood bilirubin). This results in jaundice. The pancreas is not divided into lobes.

The costo-diaphragmatic recess is the lowest extent of the pleural cavity or sac. Any fluid in the pleura will by gravity accumulate here when a patient is standing erect.

The suprarenal veins or also known as the veins of Warshaw, are the veins that receive blood from the suprarenal glands. These veins receive blood from the medullary venous plexus and the cortex of the adrenal glands (suprarenal glands). They are two in number – the left and the right suprarenal veins. The right suprarenal vein drains into the inferior vena cava while the left suprarenal vein drains into the left renal vein. This therefore means that in the case of a metastasizing tumour involving the left suprarenal vein, the tumour will most likely extend from the left suprarenal vein to the left renal vein into which it drains.

Based on the aforementioned findings in this case, the most likely diagnosis is medullary carcinoma of the thyroid associated with multiple endocrine neoplasia (MEN).

Medullary thyroid cancer is a tumour of the parafollicular cells (C cells) of the thyroid and is neural crest in origin. It may be familial and occur as part of the MEN 2A disease spectrum. Less than 10% of thyroid cancers are of this type with patients typically presenting as children or young adults. Diarrhoea occurs in 30% of the cases. In association with MEN syndromes, medullary thyroid cancers are always bilateral and multicentric. Spread may either be lymphatic or haematogenous, and as these tumours are not derived primarily from thyroid cells, they are not responsive to radioiodine.

Toxic nodular goitre is very rare. In sporadic medullary carcinoma of the thyroid, patients typically present with a unilateral solitary nodule and it tends to spread early to the lymph nodes in neck.

In the stomach and around the duodenum, there are many arterial anastomoses. Ligation of the gastroduodenal artery would result in the retrograde flow of blood from the left gastroepiploic artery to the right gastroepiploic artery. The blood flows into the right gastroepiploic artery, a branch of the gastroduodenal artery from the left gastroepiploic artery that branches from the splenic artery. This retrograde blood flow is aimed at providing alternate blood flow to the greater curvature of the stomach.