The ureter runs anterior to the vertebrae at the level of L2 to L5, and stones are usually seen at these points on x-ray.

They can also be seen at the level of the sacro-iliac joints.

Oxytocin is secreted by the posterior pituitary along with Antidiuretic Hormone (ADH). It increases the contraction of the upper segment (fundus and body) of the uterus whereas the lower segment is relaxed facilitating the expulsion of the foetus.

Oxytocin acts through G protein-coupled receptor and phosphoinositide-calcium second messenger system to contract uterine smooth muscle.

It has 0.5 to 1 % ADH activity introducing possibilities of water intoxication when used in high doses.

The sensitivity of the uterus to oxytocin increases as the pregnancy progresses.

It is used for induction of labour in post maturity and uterine inertia.

The following is the Advanced Trauma Life Support (ATLS) classification of haemorrhagic shock:

Class I haemorrhage:
It has blood loss up to 15%. There is very less tachycardia, and no changes in blood pressure, RR or pulse pressure. Usually, fluid replacement is not required.

Class II haemorrhage:
It has 15-30% blood loss, equivalent to 750 – 1500 ml. There is tachycardia, tachypnoea and a decrease in pulse pressure. Patient may be frightened, hostile and anxious. It can be stabilised by crystalloid and blood transfusion.

Class III haemorrhage:
There is 30-40% blood loss. It portrays inadequate perfusion, marked tachycardia, tachypnoea, altered mental state and fall in systolic pressure. It requires blood transfusion.

Class IV haemorrhage:
There is > 40% blood volume loss. It is a preterminal event, and the patient will die in minutes. It portrays tachycardia, significant depression in systolic pressure and pulse pressure, altered mental state, and cold clammy skin. There is need for rapid transfusion and surgical intervention.

Prednisolone 5 mg is the same as 20 mg hydrocortisone.

Prednisolone 40 mg is the same as 8 x 20 mg or 160 mg of prednisolone.

Mineralocorticoid effects and variations in action duration are not taken into account in these comparisons.

5 mg of prednisolone is the same as Dexamethasone 750 mcg, Hydrocortisone 20 mg, Methylprednisolone 4 mg, and Cortisone acetate 25 mg.

When the emergency oxygen flush is pressed, 100% oxygen is supplied from the common gas outlet. This gas bypasses BOTH flowmeters and vaporisers. The flow of oxygen is usually 45 l/min at a PRESSURE OF 400 kPa.

There is an increased risk of pulmonary barotrauma when the emergency flush is pressed, especially when anaesthetising paediatric patients.

The inappropriate use of the flush causes dilution of anaesthetic gases and this increases the possibility of anaesthetic awareness .

Sodium concentration for different fluids
3% N saline 513 mmol/L
5% N saline 856 mmol/L
0.9% N saline 154 mmol/L
Hartmann’s solution 131 mmol/L
0.45% N saline with 5% glucose 77 mmol/L

This means that:

500 mL 5% N saline contains 428 mmol of sodium
1000 mL 3% N saline contains 513 mmol of sodium
3500 mL 0.9% N saline contains 539 mmol of sodium
4000 mL Hartmann’s contains 524 mmol of sodium
6000 mL 0.45% N saline with 5% glucose contains 462 mmol of sodium.

In the Child-Pugh classification system, the following 5 components are determined or calculated in order:

Ascites

Grade of encephalopathy

Serum bilirubin (?mol/L)

Serum Albumin (g/L)

Prothrombin time or INR

Raised liver enzymes are not the component of the classification system.

Ligamentum venosum is an anterior relation of the liver: The ligamentum venosum, the fibrous remnant of the ductus venosus of the fetal circulation, lies posterior to the liver. It lies in the fossa for ductus venosus that separates the caudate lobe and the left lobe of the liver.

The portal triad contains three important tubes: 1. Proper hepatic artery 2. Hepatic portal vein 3. Bile ductules It also contains lymphatic vessels and a branch of the vagus nerve.

The bare area of the liver is a large triangular area that is devoid of any peritoneal covering. The bare area is attached directly to the diaphragm by loose connective tissue. This nonperitoneal area is created by a wide separation between the coronary ligaments.

The porta hepatis is a fissure in the inferior surface of the liver. All the neurovascular structures (except the hepatic veins) and hepatic ducts enter or leave the liver via the porta hepatis. It contains the sympathetic branch to the liver and gallbladder and the parasympathetic, hepatic branch of the vagus nerve. The caudate lobe (segment I) lies in the lesser sac on the inferior surface of the liver between the IVC on the right, the ligamentum venosum on the left, and the porta hepatis in front

The question mentions a quantitative, ratio scale data set. The use of mean would be ideal under normal circumstances, however, in this situation median is preferred as it is less sensitive to the skewness of data. The median is usually preferred to other measures of central tendency when your data set is skewed (i.e., forms a skewed distribution)

T3 is produced by peripheral de-iodination of T4. It is more active than T4.

TBG, like most binding proteins, is increased in pregnancy. Because of this, measurement of free thyroid hormone concentration is more important than total.

T4 and T3 concentrations are decreased in Illness and starvation.

L-T4 that is the active molecule while D-T4 is inactive.

The inguinal triangle of Hesselbach’s is an important clinical landmark on the posterior wall of the inguinal canal. It has the following relations:
Inferiorly – medial third of the inguinal ligament
Medially – lower lateral border of the rectus abdominis
Laterally – inferior epigastric vessels

Direct inguinal hernia is when the bowel bulges directly through the abdominal wall. These hernias usually protrude through Hesselbach’s triangle

Both incidence and prevalence are indicators of the disease frequency. While incidence tells us about the number of cases reported per population in a provided time period, prevalence is the factor you should be vigilant about as it tells us about the total number of cases that have been reported in a population at a particular point of time.

Cardiac output = stroke volume x heart rate

Left ventricular ejection fraction = (stroke volume / end diastolic LV volume ) x 100%

Stroke volume = end diastolic LV volume – end systolic LV volume

Pulse pressure = Systolic Pressure – Diastolic Pressure

Systemic vascular resistance = mean arterial pressure / cardiac output
Factors that increase pulse pressure include:
-a less compliant aorta (this tends to occur with advancing age)
-increased stroke volume

PaCO2 is one of the most important factors that regulate cerebral vascular tone. CO2 induces cerebral vasodilatation and as a result, it increases CBF. Between 20 mmHg (2.7 kPa) and 80 mmHg (10.7 kPa), there is a linear increase of PaCO2.

Sometimes, there are areas where auto regulation has failed locally but not globally. Similarly, local vs. systemic acidosis will have similar effects. When the PaO2 falls below 50 mmHg (6.5 kPa), the CBF progressively increases.

An increase in the cerebral metabolic rate for oxygen (CMRO2) and therefore CBF can be caused by hyperthermia.
A late feature of cerebral injury is hyperthermia secondary to hypothalamic injury. Therefore this is not the most likely cause of an increased CBF in this scenario.

The concentration of solute particles per litre (mosm/L) = the osmolarity of a solution. Changes in water content, ambient temperature, and pressure affects osmolarity. The osmolarity of any solution can be calculated by adding the concentration of key solutes in it.

Individual manufacturers of crystalloids and colloids may have different absolute values but they are similar to these.

0.45% N. Saline with 5% glucose:
Tonicity – hypertonic
Osmolarity – 405 mosm/L
Kilocalories (kCal) – 107

0.9% N. Saline:
Tonicity – isotonic
Osmolarity – 308 mosm/L
Kilocalories (kCal) – 0

5% Dextrose:
Tonicity – isotonic
Osmolarity – 253 mosm/L
Kilocalories (kCal) – 170

Gelofusine (154 mmol/L Na, 120 mmol/L Cl):
Tonicity – isotonic
Osmolarity – 274 mosm/L
Kilocalories (kCal) – 0

Hartmann’s solution:
Tonicity – isotonic
Osmolarity – 273 mosm/L
Kilocalories (kCal) – 9

Insulin is secreted from the ? cells of the pancreas. It consists of 51 amino acids arranged in two chains. It interacts with cell surface receptors (not the nuclear receptors and thus mechanism of action is not similar to steroids).
Since insulin can pass from plasma to interstitium and lymphatics, it can be measured in lymph but the concentrations here can be up to 30% less than that of plasma.

It decreases blood glucose by stimulating the entry of glucose in muscle and fat (by increasing the synthesis of Glucose transporters)

Intra-arterial blood pressure monitoring is a common place procedure in the ICU. It is used to provide accurate beat-to-beat information using a pressure wave displayed on a monitor.

It involves catheter insertion in a peripheral artery (most commonly the radial, brachial and dorsalis pedis arteries). Each subsequent contraction of cardiac muscles results in pressure wave which induces a mechanical motion of flow in the catheter. This mechanical motion is then passed on to a transducer through a rigid fluid-filled tubing. The transducer is the able to process this mechanical motion into electrical signals which are displayed as arterial waves and pressure represented numerically on the monitor.

The transducer should be placed at the same level as the heart on the phlebostatic axis, and at the level of the atria (the 4th intercostal space, in the mid-axillary line).

Air bubbles and catheter tubing with longer lengths result in wave dampening (rounding of the resulting pressure waves). This dampening causes a decrease in systolic pressure, and an increase in diastolic pressure.

The pectinate muscles (musculi pectinati) are parallel muscular ridges that extend anterolaterally on the right atrial walls. The most prominent pectinate muscle, which forms the bridge of the sulcus terminalis internally, is the taenia sagittalis (second crest or septum spurium).

In the left atrium, the pectinate muscles are confined to the inner surface of its atrial appendage. They tend to be fewer and smaller than in the right atrium. This is due to the embryological origin of the auricles, which are the true atria.

Pectinate muscles of the atria are different from the trabeculae carneae, which are found on the inner walls of both ventricles.

The interior of the right atrium has five distinct features:
1. Sinus venarum – smooth, thin-walled posterior part of the right atrium where the SVC, IVC, and coronary sinus open
2. Musculi pectinati – a rough anterior wall of pectinate muscles
3. Tricuspid valve orifice – the opening through which the right atrium empties blood into the right ventricle
4. Crista terminalis – separates the rough (musculi pectinati) from the smooth (sinus venarum) internally
5. Fossa ovalis – a thumbprint size depression in the interatrial septum, which is a remnant of the oval foramen and its valve in the foetus

Since the data is normally distributed, 95.4% of the values lie with in 2 standard deviations from mean. The rest of the 4.6% are distributed symmetrically outside of that range which means 2.3% of the values lie above 2 standard deviations of the mean.

Standard error can be calculated by the following formula:
Standard Error= (Standard Deviation)/√(Sample Size)
= (16) / √(100)
= 16 / 10
= 1.6

The external urethral sphincter functions to provide voluntary control of urine flow from the bladder to the urethra.

It receives its innervation from the branches of the pudendal nerve which originate from S2, S3 and S4.

Sixty-seven percent of filtered water is reabsorbed in the proximal tubule. The driving force for water reabsorption is a transtubular osmotic gradient established by reabsorption of solutes (e.g., NaCl, Na+-glucose).

Henle’s loop reabsorbs approximately 25% of filtered NaCl and 15% of filtered water. The thin ascending limb reabsorbs NaCl by a passive mechanism, and is impermeable to water. Reabsorption of water, but not NaCl, in the descending thin limb increases the concentration of NaCl in the tubule fluid entering the ascending thin limb. As the NaCl-rich fluid moves toward the cortex, NaCl diffuses out of the tubule lumen across the ascending thin limb and into the medullary interstitial fluid, down a concentration gradient as directed from the tubule fluid to the interstitium. This mechanism is known as the counter current multiplier.

The distal tubule and collecting duct reabsorb approximately 8% of filtered NaCl, secrete variable amounts of K+ and H+, and reabsorb a variable amount of water (approximately 8%-17%).

Glucose transport is a highly regulated process accomplished mostly by facilitated diffusion using carrier proteins to cross cell membranes.

There are many transporters, but the most important are known as glucose transporters (GLUTs).

Stresses in various form of acute and chronic forms affect the activity of glucose transporters.
They are responsive to many types of metabolic stress, including hypoxia, injury, hypoglycaemia, numerous metabolic inhibitors, stress hormones, and other influences such as growth factors.

Numerous signalling pathways appear to be involved in transporter regulation.

New evidence suggests that stresses regulating GLUTs are not only acute biological stresses. In addition, chronic low-grade inflammation, and their associated chronic diseases also lead to altered glucose transport. These include obesity, type 2 diabetes, cardiovascular disease, and the growth and spread of many tumours that are affected by altered glucose transporters. Some of these glucose transport effects are compensatory, while others are pathogenic.

Ultimately, deliberate manipulation of GLUTs could be used as treatment for some of these chronic diseases.

During fetal development, blood oxygenated by the placenta flows to the foetus through the umbilical vein, bypasses the fetal liver through the ductus venosus, and returns to the fetal heart through the inferior vena cava.

Blood returning from the inferior vena cava then enters the right atrium and is preferentially shunted to the left atrium through the patent foramen ovale. Blood in the left atrium is then pumped from the left ventricle to the aorta. The oxygenated blood ejected through the ascending aorta is preferentially directed to the fetal coronary and cerebral circulations.

Deoxygenated blood returns from the superior vena cava to the right atrium and ventricle to be pumped into the pulmonary artery. Fetal pulmonary vascular resistance (PVR), however, is higher than fetal systemic vascular resistance (SVR); this forces deoxygenated blood to mostly bypass the fetal lungs. This poorly oxygenated blood enters the aorta through the patent ductus arteriosus and mixes with the well-oxygenated blood in the descending aorta. The mixed blood in the descending aorta then returns to the placenta for oxygenation through the two umbilical arteries.

Femoral nerve lesion (L2,L3 and L4) is characterised by weakness of the quadriceps femoris muscle. This results in weakness of extension of the knee, loss of sensation over the front of the thigh, and loss of the knee jerk reflex.

The skin over the lateral aspect of the thigh and knee, and the lower lateral quadrant of the buttock is supplied by the lateral cutaneous nerve of the thigh (L1,2).

The adductors of the hip are supplied by the obturator nerve (L2-4). This nerve also supplies sensation to the inner thigh.

Variance and standard deviation indicate the dispersion of the plot from mean value and thus are not really helpful in summarizing the mean.

Range is the difference between maximum and minimum value that is 45 in this case.

The mean in this case is 6.2 due to the presence of an outlier 45. In the presence of outlier mean can be misleading as it is quite sensitive to skewness in data.

Mode is the most frequent value. In this case mode has 4 values: 0,1,2,4.

In case of skewedness, median is the most apt representative of the mean as it is not affected by outliers. In this case since the data set has even values i.e. 10. Median is the average of the 5th & 6th entry after arranging the data in ascending order like that in case of the question (0,0,1,1,2,2,3,4,4,45). This turns out to be 2.

After ingestion of more than 150 mg/kg paracetamol within 24 hours, hepatotoxicity can occur but can also develop rarely after ingestion of doses as low as 75 mg/kg within 24 hours. Hepatocellular damage will not occur in this patient and therefore no need to engage management pathway for paracetamol overdose. If his weight was <33 kg or he already had a history of impaired liver function, then the management would bde different. Subsequent post-operative doses will be a standard dose of 1 g 6 hourly. This is a drug administration error and should be reported as an incident even though the patient will not be harmed.

Oxytocin is structurally similar to Antidiuretic Hormone (ADH) and thus oxytocin can cause water intoxication (due to an ADH like action)

Oxytocin is secreted by the posterior pituitary along with ADH. It increases uterine contractions – the contraction of the upper segment (fundus and body) of the uterus whereas the lower segment is relaxed facilitating the expulsion of the foetus

Antidiuretic hormone (ADH) also called vasopressin is released from the posterior pituitary in response to hypertonicity and increases fluid reabsorption from the kidney.

The descending thoracic aorta begins at the lower border of T4 near the midline as a continuation of the arch of the aorta. It descends and ends at the level of T12 at the aortic hiatus in the diaphragm, where it becomes the abdominal aorta.

The aorta gives off the following branches: (descending order)

1. Bronchial arteries
2. Mediastinal arteries
3. Oesophageal arteries
4. Pericardial arteries
5. Superior phrenic arteries

The posterior intercostal arteries are branches that originate throughout the length of the posterior aspect of the descending thoracic aorta.

The inferior thyroid artery is usually derived from the thyrocervical trunk, a branch of the subclavian artery.