The pulmonary artery pressure (PA pressure) is a measure of the blood pressure found in the main pulmonary artery. The hydrostatic pressure of the pulmonary circulation refers to the actual pressure inside pulmonary vessels relative to atmospheric pressure. Hydrostatic (blood pressure) in the pulmonary vascular bed is low compared with that of similar systemic vessels. The mean pulmonary arterial pressure is about 15 mmHg (ranging from about 13 to 19 mmHg) and is much lower than the average systemic arterial pressure of 90 mmHg.

Blood that bypasses the ventilated parts of lung and enters the arterial circulation directly is known as shunted blood. It happens in normal people due to mixing of arterial blood with bronchial and some myocardial venous blood (which drains into the left heart). Diffusion limitation and reaction velocity with haemoglobin are immeasurably small. CO2 unloading will not affect the difference between alveolar and arterial p(O2). A large VSD will result in much lower arterial O2 as compared to alveolar O2.

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.

Answer: Staphylococcus aureus

Mastitis is defined as inflammation of the breast. Although it can occur spontaneously or during lactation, this discussion is limited to mastitis in breastfeeding women, with mastitis defined clinically as localized, painful inflammation of the breast occurring in conjunction with flu-like symptoms (e.g., fever, malaise). Mastitis is especially problematic because it may lead to the discontinuation of breast-feeding, which provides optimal infant nutrition. Mastitis occurs in approximately 10 percent of U.S. mothers who are breastfeeding, and it can lead to the cessation of breastfeeding. The risk of mastitis can be reduced by frequent, complete emptying of the breast and by optimizing breastfeeding technique. Sore nipples can precipitate mastitis. The differential diagnosis of sore nipples includes mechanical irritation from a poor latch or infant mouth anomalies, such as cleft palate or bacterial or yeast infection. The diagnosis of mastitis is usually clinical, with patients presenting with focal tenderness in one breast accompanied by fever and malaise. Treatment includes changing breastfeeding technique, often with the assistance of a lactation consultant. When antibiotics are needed, those effective against Staphylococcus aureus (e.g., dicloxacillin, cephalexin) are preferred. As methicillin-resistant S. aureus becomes more common, it is likely to be a more common cause of mastitis, and antibiotics that are effective against this organism may become preferred. Continued breastfeeding should be encouraged in the presence of mastitis and generally does not pose a risk to the infant. Breast abscess is the most common complication of mastitis. It can be prevented by early treatment of mastitis and continued breastfeeding. Once an abscess occurs, surgical drainage or needle aspiration is needed. Breastfeeding can usually continue in the presence of a treated abscess.

Answer: Intravenous naloxone

Naloxone is a medication approved by the Food and Drug Administration (FDA) to prevent overdose by opioids such as heroin, morphine, and oxycodone. It blocks opioid receptor sites, reversing the toxic effects of the overdose. Naloxone is administered when a patient is showing signs of opioid overdose. The medication can be given by intranasal spray, intramuscular (into the muscle), subcutaneous (under the skin), or intravenous injection.

Several conditions and drugs can cause pinpoint pupils, including:
Prescription opioids or narcotics
Some medications have opioids or narcotics in them. Opioids, including morphine, are drugs commonly used for pain relief. Opioids can affect a person psychologically and are highly addictive.

People often take prescription opioids in pill form to treat severe post-surgical pain, such as from dental surgery, or for long-term pain, as with some cancers.

Prescription opioids that may cause pinpoint pupils include:

oxycodone
morphine
hydrocodone
codeine
methadone

Juvenile polyps are benign hamartomas with neoplastic potential that are the most frequent gastrointestinal polyp of childhood, with the peak incidence between 3 and 5 years of age.. The presence of multiple juvenile polyps may indicate a premalignant condition commonly named juvenile polyposis coli or juvenile polyposis syndrome (JPS). In contrast, single or solitary juvenile polyps generally are considered benign sporadic lesions that confer little to no future risk of malignancy. Most frequent presentation is painless rectal bleeding. Other features include a prolapsing rectal mass and abdominal pain.

In this patient who has stage III colon cancer, the survival rate is 30-60%. For stage I or Dukes’ stage A disease, the 5-year survival rate after surgical resection exceeds 90%. For stage II or Dukes’ stage B disease, the 5-year survival rate is 70%–85% after resection, with or without adjuvant therapy. For stage III or Dukes’ stage C disease, the 5-year survival rate is 30%– 60% after resection and adjuvant chemotherapy and for stage IV or Dukes’ stage D disease, the 5-year survival rate is poor (approximately 5%).

Bacteroides species are anaerobic bacteria that are predominant components of the bacterial florae of mucous membranes and are therefore a common cause of endogenous infections. Bacteroides infections can develop in all body sites, including the CNS, the head, the neck, the chest, the abdomen, the pelvis, the skin, and the soft tissues. Inadequate therapy against these anaerobic bacteria may lead to clinical failure.

These bacteria are resistant to penicillins, mostly through the production of beta-lactamase. Anaerobic bacteria can infect deep wounds, deep tissues, and internal organs where there is little oxygen. These infections are characterized by abscess formation, foul-smelling pus, and tissue destruction. Anaerobes outnumber aerobes by 1000:1 in the large intestine; thus, they play an important role in almost all intra-abdominal infections.

Secondary peritonitis and abdominal abscesses generally occur after entry of enteric organisms into the peritoneal cavity through perforation of the intestine or other viscus as a result of obstruction, infarction, or trauma.

Most visceral abscesses (e.g., hepatic), chronic cholecystitis, perforated and gangrenous appendicitis, postoperative wound infections and abscesses, diverticulitis, and any infection associated with faecal contamination of the abdominal cavity involve both aerobes and anaerobes.

The patient has a Weber type A fracture, based on the Danis-Weber classification system for lateral malleolar fractures. It is a stable ankle injury and can, therefore, be managed conservatively. Whilst this patient could also be treated in a below-knee plaster, most clinicians, nowadays, treat this injury in an ankle boot. Patients are also advised to mobilise with the ankle boot as pain allows and can wean themselves off as the symptoms improve.

The Danis-Weber classification system is based on the level of the fibula fracture in relation to the syndesmosis (the connection between the distal ends of the tibia and fibula). The more proximal, the greater the risk of syndesmotic injury and, therefore, fracture instability.

1. Weber type A: fracture below the level of the syndesmosis
2. Weber type B: fracture at the level of the syndesmosis/level of the tibial plafond
3. Weber type C: fracture above the level of the syndesmosis. This includes Maisonneuve fracture (proximal fibula fracture) which can be associated with ankle instability.

Ankle fractures are common. They affect men and women in equal numbers, but men have a higher rate as young adults (sports and contact injuries), and women have a higher rate post-menopausal (fragility-type fractures). Patients present, following a traumatic event, with a painful, swollen ankle, and reluctance/inability to bear weight.

Radiographs of clearly deformed or dislocated joints are not necessary, and removing the pressure on the surrounding soft tissues from the underlying bony deformity is the priority. If the fracture pattern is not clinically obvious, then plain radiographs are appropriate. Antero-posterior, lateral, and mortise views are essential to evaluate fracture displacement and syndesmotic injury. Decreased tibiofibular overlap, medial joint clear space, and lateral talar shift all indicate a syndesmotic injury.

When deciding upon treatment for an ankle fracture, one must consider both the fracture and the patient. Diabetic patients and smokers are at greater risk of post-operative complication, especially wound problems and infection. Likewise, the long term outcome of post-traumatic arthritis from a malunited ankle fracture is extremely important for a young patient, but not as relevant in the elderly. Unimalleolar Weber type A fractures, by definition, are stable and therefore, can be mobilised fully in an ankle boot.

The middle sacral artery arises from behind the aorta a little above the point of its bifurcation to descend down in front of L4,5, the sacrum and coccyx.

The duodenum is the only organ in the list that would not be affect by the clumping of the splenic artery as it is supplied by common hepatic artery (through the gastroduodenal artery) and the superior mesenteric artery (through the inferior pancreaticoduodenal artery). The splenic artery is the artery that supplies the spleen with oxygenated blood. The splenic artery before reaching the spleen also gives off branches that supply the stomach and the pancreas. The greater curvature and the fundus of the stomach is supplied the short gastric artery which branches off from the splenic artery. The left portion of the greater curvature of the stomach together with the greater omentum is supplied by the left gastro-omental artery of the splenic artery. The body and tail of the pancreas is supplied by branches of the splenic artery through the dorsal and superior pancreatic arteries and the caudal pancreatic arteries respectively.

This is most likely a case of pyelonephritis.

Acute pyelonephritis is a common bacterial infection of the renal pelvis and kidneys most often seen in young adult women. History and physical examination are the most important tools for diagnosis. Most patients have fever, although it may be absent early in the illness. E. coli is the most common pathogen in acute pyelonephritis.

For diagnosing the disease:
1. A positive urinalysis confirms the diagnosis in patients with a compatible history and physical examination.
2. Urine culture should be obtained in all patients to guide antibiotic therapy if the patient does not respond to initial empirical antibiotic regimens.
3. Imaging, usually with contrast-enhanced CT scan, is not necessary unless there is no improvement in the patient’s symptoms or if there is recurrence of symptoms after initial improvement.

Outpatient treatment is appropriate for most patients. Inpatient therapy is recommended for patients who have severe illness or in whom a complication is suspected. Oral beta-lactam antibiotics and trimethoprim/sulfamethoxazole are generally inappropriate for outpatient therapy because of high resistance rates. Several antibiotic regimens can be used for inpatient treatment, including fluoroquinolones, aminoglycosides, and cephalosporins.

In a surgical patient, hepatic dysfunction translates into an increased risk of infection, haemorrhage, thrombosis, and a prolonged half-life of numerous drugs (e.g., opioids and benzodiazepines). The associated imbalance of neuroendocrine mediators (e.g., vasopressin, renin-angiotensin-aldosterone system, and nitric oxide) also potentiates sodium and fluid retention, resulting in a background hyperdynamic circulation with splanchnic venous congestion and systemic vasodilation.
In emergency surgery, stress response to the underlying condition, anaesthesia, and surgical trauma increase the risk of hepatic decompensation and associated multi-system failure. Changes in hepatic perfusion with shock and fluid shifts further compromise hepatocellular synthetic and excretory functions. In addition, endotoxemia from gram-negative sepsis potentiates platelet aggregation and creates a state of low-grade disseminated intravascular coagulation.
Activation of the renin-angiotensin-aldosterone system with hypersecretion of vasopressin acts as compensatory mechanisms to preserve arterial pressure and replenish effective circulating volume when blood is pooled in the splanchnic territory. With the progression of cirrhosis, avidity for water and sodium increases, and dilutional hyponatremia results from water retention. In advanced cases, exacerbation of these abnormalities leads to hepatorenal syndrome (HRS). HRS is characterized by a rapid decline in renal function with low urinary excretion of sodium due to severe renal vasoconstriction and diminished or absent cortical perfusion. This syndrome is potentially reversible but carries an extremely poor prognosis.

Owing to raised intra-abdominal pressure due to ascites and muscle weakness from decreased muscle mass and malnutrition, umbilical and inguinal hernia incidence is higher in patients with cirrhosis.
If the patient with cirrhosis has umbilical hernia with obstructive symptoms such as intermittent incarceration or trophic skin changes, surgical repair should be considered.

Euvolemia and electrolyte homeostasis should be maintained under strict clinical and laboratory monitoring. Acute kidney injury in the absence of hemodynamic instability, use of nephrotoxic drugs, or parenchymal renal disease suggests the diagnosis of hepatorenal syndrome. Additional diagnostic criteria include no improvement in renal function after volume expansion with albumin and diuretic withdrawal. Treatment of hepatorenal syndrome requires the use of splanchnic vasoconstrictors (terlipressin, noradrenalin, or midodrine) and albumin infusion. Improved renal function has been demonstrated with medical treatment, but a mortality benefit is only ultimately achieved with liver transplantation. TIPS placement and renal and hepatic replacement therapies can be indicated as bridging strategies.

Pancreatic cancer typically has a poor prognosis, partly because the cancer usually initially remains symptomless, leading to locally advanced or metastatic disease at the time of diagnosis. Median survival from diagnosis is around 3–6 months. Even in those suitable for resectional surgery, 5-year survival rates are still only 30 per cent.

The suprascapular nerve arises from the cervical spinal nerves 5 and 6 after coming together to form common trunk. This nerve supplies the supraspinatus and infraspinatus muscles giving off branches to the shoulder joint.

The sternal angle, a key landmark used in the clinic for auscultating for heart sounds, is the point of attachment of the costal cartilage of rib 2 to the sternum. It thus corresponds to the location of the second rib. A horizontal plane through the sternal angle traverses the T4/T5 intervertebral disc and marks the inferior boundary of the superior mediastinum.

Hypoxic pulmonary vasoconstriction is a local response to hypoxia resulting primarily from constriction of small muscular pulmonary arteries in response to reduced alveolar oxygen tension. This unique response of pulmonary arterioles results in a local adjustment of perfusion to ventilation. This means that if a bronchiole is obstructed, the lack of oxygen causes contraction of the pulmonary vascular smooth muscle in the corresponding area, shunting blood away from the hypoxic region to better-ventilated regions. The purpose of hypoxic pulmonary vasoconstriction is to distribute blood flow regionally to increase the overall efficiency of gas exchange between air and blood.

Answer: Fibroadenoma

A fibroadenoma is a painless, unilateral, benign (non-cancerous) breast tumour that is a solid, not fluid-filled, lump. It occurs most commonly in women between the age of 14 to 35 years but can be found at any age. Fibroadenomas shrink after menopause, and therefore, are less common in post-menopausal women. Fibroadenomas are often referred to as a breast mouse due to their high mobility. Fibroadenomas are a marble-like mass comprising both epithelial and stromal tissues located under the skin of the breast. These firm, rubbery masses with regular borders are often variable in size.

Fibroadenoma tends to occur in early age. It is most commonly found in adolescents and less commonly found in postmenopausal women. The incidence of fibroadenoma decreases with increasing age and generally found before 30 years of age in females in the general population. It is estimated that 10% of the world’s female population suffers from fibroadenoma once in a lifetime.

The cricothyroid muscle is the only tensor muscle of the larynx aiding with phonation. It attaches to the anterolateral aspect of the cricoid and the inferior cornu and lower lamina of the thyroid cartilage. Its action tilts the thyroid forward to help tense the vocal cords.

Coagulation of blood is a complex process and an important part of haemostasis. There are two main pathways related to coagulation: the contact activation pathway/intrinsic pathway and tissue factor/extrinsic pathway. The extrinsic pathway is activated by external trauma that causes blood to escape from the vascular system. This pathway is quicker than the intrinsic pathway and involves factor VII. The intrinsic pathway is activated by trauma inside the vascular system, and initiated by platelets, exposed endothelium, chemicals, or collagen. This pathway is slower than the extrinsic pathway, but more important. It involves factors XII, XI, IX, VIII. Both pathways meet to finish the formation of a clot in what is known as the common pathway. The common pathway involves factors I, II, V, and X. They converge on the common pathway in which activation of prothrombin to thrombin leads to conversion of fibrinogen to fibrin and clot formation.

Epidural hematoma, also known as epidural bleeding, is a type of traumatic brain injury (TBI) in which a build-up of blood occurs between the dura mater (the tough outer membrane of the central nervous system) and the skull. The spinal cord is also covered by a layer of dura mater, so epidural bleeds may also occur in the spinal column. Often due to trauma, the condition is potentially deadly because the build-up of blood may increase pressure in the intracranial space, compressing delicate brain tissue, and causing brain shift. The condition is present in one to three percent of head injuries. Around 15–20% of epidural hematomas are fatal.

Typhoid fever is caused by virulent bacteria called Salmonella typhi. Salmonella typhi spread through contaminated food or water and occasionally through direct contact with someone who is infected.

The jugular foramen is a large foramen in the base of the skull. It is located behind the carotid canal and is formed in front by the petrous portion of the temporal bone, and behind by the occipital bone. Cranial nerves IX, X, and XI and the internal jugular vein pass through the jugular foramen.

There is strong evidence to support haemostatic resuscitation in the setting of massive haemorrhage due to trauma. This advocates the use of 1:1:1 ratio.

Uncontrolled haemorrhage accounts for up to 39% of all trauma-related deaths. In the UK, approximately 2% of all trauma patients need massive transfusion. Massive transfusion is defined as the replacement of a patient’s total blood volume in less than 24 hours or the acute administration of more than half the patient’s estimated blood volume per hour. During acute bleeding, the practice of haemostatic resuscitation has been shown to reduce mortality rates. It is based on the principle of transfusion of blood components in fixed ratios. For example, packed red cells, FFP, and platelets are administered in a ratio of 1:1:1.

An upper motor neuron lesion affects the neural pathway above the anterior horn cell or motor nuclei of the cranial nerves, whereas a lower motor neurone lesion affects nerve fibres travelling from the anterior horn of the spinal cord to the relevant muscles. An upper motor neurone lesions results in the following:
– Spasticity in the extensor muscles (lower limbs) or flexor muscles (upper limbs).
– ‘clasp-knife’ response where initial resistance to movement is followed by relaxation
– Weakness in the flexors (lower limbs) or extensors (upper limbs) with no muscle wasting
– Brisk tendon jerk reflexes
– Positive Babinski sign (on stimulation of the sole of the foot, the big toe is raised rather than curled downwards)

The mesangium is an inner layer of the glomerulus, within the basement membrane surrounding the glomerular capillaries. The mesangial cells are phagocytic and secrete the amorphous basement membrane-like material known as the mesangial matrix. They are typically separated from the lumen of the capillaries by endothelial cells. The other type of cells in the mesangium are the extraglomerular mesangial cells which form the juxtaglomerular apparatus in combination with two other types of cells: the macula densa of the distal convoluted tubule and juxtaglomerular cells of the afferent arteriole. This apparatus controls blood pressure through the renin–angiotensin–aldosterone system.

The patient is in hypovolemic shock, he is transfused with blood, this fluid resuscitation will result in a decreased sympathetic discharge and adequate ventricular filling which will result in the decreases TPR with an increased CO and cardiac filling pressures

The fundus of the stomach along with the greater curvature of the stomach receive blood supply from the short gastric artery. The short gastric artery arises from the end of the splenic artery. The ligation of the splenic artery therefore would cause a disruption of blood supply to the fundus of the stomach.

The rate of filtration at any point along a capillary depends on a balance of forces sometimes called Starling’s forces after the physiologist who first described their operation in detail. The Starling principle of fluid exchange is key to understanding how plasma fluid (solvent) within the bloodstream (intravascular fluid) moves to the space outside the bloodstream (extravascular space). Fluid movement = k[(pc– pi)–(Πc– Πi)] where k = capillary filtration coefficient, pc = capillary hydrostatic pressure, pi= interstitial hydrostatic pressure, Πc = capillary colloid osmotic pressure, Πi = interstitial colloid osmotic pressure. Therefore: 1 × [capillary hydrostatic pressure (17) – interstitial fluid hydrostatic pressure (–3)] – [plasma colloid osmotic pressure (28) – interstitial fluid colloid osmotic pressure (8)] = 0 mmHg

The combination of a crush injury, limb swelling, and inability to move digits raises suspicion of compartment syndrome that would require a fasciotomy.

Compartment syndrome is a particular complication that may occur following fractures, especially supracondylar fractures and tibial shaft injuries. It is characterised by raised pressure within a closed anatomical space which may, eventually, compromise tissue perfusion, resulting in necrosis.

The clinical features of compartment syndrome include:
1. Pain, especially on movement
2. Paraesthesia
3. Pallor
4. Paralysis of the muscle group may also occur

Diagnosis is made by measurement of intracompartmental pressure. Pressures >20mmHg are abnormal and >40mmHg are diagnostic.

Compartment syndrome requires prompt and extensive fasciotomy. Myoglobinuria may occur following fasciotomy, resulting in renal failure. Therefore, aggressive IV fluids are required. If muscle groups are frankly necrotic at fasciotomy, they should be debrided, and amputation may have to be considered.