The action of class 1 anti-arrhythmic is sodium channel blockade. Subclasses of this action reflect effects on the action potential duration (APD) and the kinetics of sodium channel blockade.

Drugs with class 1A prolong the APD and refractory period, and dissociate from the channel with intermediate kinetics.

Drugs with class 1B action shorten the APD in some tissues of the heart, shorten the refractory period, and dissociate from the channel with rapid kinetics.

Drugs with class 1C action have minimal effects on the APD and the refractory period, and dissociate from the channel with slow kinetics.

The deep inguinal ring is the entrance of the inguinal canal. It is an opening in the transversalis fascia around 1 cm above the inguinal ligament. Therefore, the superolateral wall is made by the transervalis fascia.

The inferior epigastric vessels run medially to the deep inguinal ring forming its inferomedial border.

The inguinal canal extends obliquely from the deep inguinal ring to the superficial inguinal ring.
An indirect inguinal hernia arises through the deep inguinal ring lateral to the inferior epigastric vessels.

Recall bias introduced when participants in a study are systematically more or less likely to recall and relate information on exposure depending on their outcome status.

In procedure bias, the researcher decides assignment of a treatment versus control and assigns particular patients to one group or the other non-randomly. This is unlikely to have occurred in this case, although it is not mentioned specifically.

Self Selection or volunteer bias occur when those subjects are selected to participate in the study who are not the representative of the entire target population. those subjects may be from high socio-economic status and practice those activities or lifestyle that improves their health.

Lead-time bias occurs when a disease is detected by a screening test at an earlier time point rather than it would have been diagnosed by its clinical appearance. In this bias, earlier detection improves the survival time in the intervention group.

The popliteal fossa is the shallow, diamond-shaped depression located in the back of the knee joint.

The structures that lie within in from superficial to deep are:

The tibial and common fibular nerve: Most superficial. They arise from the sciatic nerve.
The popliteal vein
The popliteal artery: Lies deepest. It arises from the femoral artery

Boundaries of the popliteal fossa:

Laterally
Biceps femoris above, lateral head of gastrocnemius and plantaris below

Medially
Semimembranosus and semitendinosus above, medial head of gastrocnemius below

Floor
Popliteal surface of the femur, posterior ligament of knee joint and popliteus muscle

Roof
Superficial and deep fascia

Peak expiratory flow rate (PEFR) is the maximum speed of air flow generated during a single forced exhaled breath. It is most useful when expressed as a percentage of the best value obtained from the patient.

Forced expiratory volume over 1 second (FEV1) is a lung parameter measured using spirometry. It is the amount of air forced out of the lung in one exhaled breath. It is a more accurate measure of lung obstructions as it doesn’t rely on effort like PEFR

PEFR and FEV1 are usually similar, but become more different in asthmatic patients as airflow becomes increasingly obstructed.

Acute severe asthma is most often diagnosed on history taking and examinations:

Respiratory rate: >25 breaths/min
Heart rate: >110 beats/min
PEFR: 33 – 50% predicted (<200L/min)
Patient state: Unable to complete a sentence in a single breath.

A chest x-ray is not routinely required, and is only indicated in specific circumstances, which are:

If a pneumomediastinum or pneumothorax is suspected
Possible life threatening asthma
Possible consolidation
Unresponsive asthma
If ventilation is required.

An echocardiograph (ECG) is not necessary in this case

Routine haematological and biochemical investigations are not urgent in this case as any abnormalities they detect will be secondary to the patient’s presentation.

An arterial blood gas (ABG) will only be indicated if SPO2 was <92% or if patient presented with life threatening symptoms.

Bucks fascia refers to the layer of loose connective tissue, nerves and blood vessels that encapsulates the penile erectile bodies, the corpa cavernosa and the anterior part of the urethra, including the entirety of the spongiose part of the urethra.

It runs with the external spermatic fascia and the penile suspensory ligament.

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.

Vecuronium is used as a part of general anaesthesia to provide skeletal muscle relaxation during surgery or mechanical ventilation. It is a monoquaternary aminosteroid (not quaternary) non- depolarising neuromuscular blocking drug.

It has a structure similar to both rocuronium and pancuronium. The only difference is the substitution of specific groups on the steroid structure.

Vecuronium is not associated with the release of norepinephrine from sympathetic nerve endings. However, Pancuronium has norepinephrine releasing the property.

The first rib is an atypical rib. It is short, wide, and flattened and lies in an oblique plane.

It has a small scalene tubercle on its medial border which marks the point of attachment of scalenus anterior. The lower surface lies on the pleura and is smooth.

The tubercle on the upper surface separates an anterior groove for the subclavian vein and a posterior groove for the subclavian artery and lower trunk of the brachial plexus.

Scalenus medius is attached to a roughened area posterior to the groove for the subclavian artery.

The upper surface gives attachment anteriorly to the subclavius muscle and costoclavicular ligament.

Since an arterial pressure transducer, and every other measuring apparatus, is prone to errors due to offset and gradient drifts, regular calibration is required to maintain accuracy of the instrument. The two-point calibration pressure values of 0 mmHg and 200 mmHg are within the physiologic range and can best compensate for the gradient drift.

Fractures to the surgical neck of the humerus are common place as it is the weakest point of the proximal humerus bone.

The structures most likely to be damaged are the axillary nerve and the posterior circumflex humeral artery as they surround the surgical neck.

The radial nerve runs along the radial groove, so injury to it would likely occur with a mid-shaft fracture of the humerus.

The brachial artery is most likely to be injured as a result of a supracondylar fracture of the humerus which increases the risk of volkmaan’s ischemic contractures.

Injury to the musculocutaneous nerve is least likely to happen and it very uncommon.

The needle should be inserted just below the skin at the mid inguinal point which is the surface indicator for the femoral artery.

Silent (S) is the most probable phenotype of the patient. In S phenotype, patients have significantly reduced levels of BChE, the lowest among the four phenotypes. Because of this, individuals with S phenotype are subjected to long periods of apnoea. In addition, their dibucaine number is very low.

Other BChE phenotypes are the following:

Usual (U)
Atypical (A)
Fluoride-resistant (F)

Staphylococcus aureus colonizes the nasopharynx in >20% of the general population.

Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to flucloxacillin.

Trimethoprim binds to dihydrofolate reductase and inhibits the reduction of dihydrofolic acid (DHF) to tetrahydrofolic acid (THF). THF is an essential precursor in the thymidine synthesis pathway and interference with this pathway inhibits bacterial DNA synthesis.

All ?-lactam antibiotics like penicillin interfere with the synthesis of the bacterial cell walls. The ?-lactam antibiotics inhibit the transpeptidases so that cross-linking (which maintains the close-knit structure of the cell wall) does not take place

The diaphragm divides the thoracic cavity from the abdominal cavity. Structures penetrate the diaphragm at different vertebral levels through openings in the diaphragm to communicate between the two cavities. The diaphragm has openings at three vertebral levels:

T8: vena cava, terminal branches of the right phrenic nerve
T10: oesophagus, vagal trunks, left anterior phrenic vessels, oesophageal branches of the left gastric vessels
T12: descending aorta, thoracic duct, azygous and hemi-azygous vein

Metabolic equivalent (MET) measures the energy expenditure of an individual.

It is calculated mathematically by:

MET = (VO2 max/weight)/3.5 = 21/3.5 = 6 METs

Where 1 MET = 3.5 mL O2/kg/minute is utilized by the body.

Note:

1 MET Eating
Dressing
Use toilet
Walking slowly on level ground at 2-3 mph
2 METs Playing a musical instrument
Walking indoors around house
Light housework
4 METs Climbing a flight of stairs
Walking up hill
Running a short distance
Heavy housework, scrubbing floors, moving heavy furniture
Walking on level ground at 4 mph
Recreational activity, e.g. golf, bowling, dancing, tennis
6 METs Leisurely swimming
Leisurely cycling along the flat (8-10 mph)
8 METs Cycling along the flat (10-14 mph)
Basketball game
10 METs Moderate to hard swimming
Competitive football
Fast cycling (14-16 mph)

The cylindrical structure(spine), starts from the foramen magnum in medulla oblongata at the skull’s base. Its length varies in gender with men having 45cm and women having up to 43 cm. The spine contains 31 pairs of spinal nerves, named according to the spinal region:
– 8 cervical nerve pairs ( C1-C8)
– 12 thoracic nerve pairs ( T1-T12)
– 5 lumbar nerve pairs (L1-L5)
– 5 sacral nerves (S1-S5) and
– 1 coccygeal nerve pair.
These spinal nerves are classified as the peripheral nervous system though they branch from the spinal cord and central nervous system. They interact directly with the spinal cord to modulate the motor and sensory information from the peripheral’s region. As the nerves emerges form the spinal cords they are known as rootlets. They join to form nerve roots, and depending on their position, we have anterior nerve roots and posterior.

The spinal cord is supplied by two posterior and one anterior spinal arteries which anastomoses caudally, at the conus medullaris.

The anterior spinal artery supplies the anterior two-thirds of the spinal cord and medulla. Disruption of the anterior spinal artery supply is characterised by ischaemia or infarction of motor tracts (corticospinal) and loss of pain and temperature sensation below the level of the lesion.

The posterior spinal arteries supply the posterior columns (posterior third of the spinal cord). Infarction of the posterior columns results in the loss of proprioceptive, vibration and two-point discrimination.

The spinal cord normally ends at the level of L1 or L2 in an adult and L3 in a newborn.

Randomisation can be used to provide control over the confounding variables during the design stage of a study however during analytical stage a technique called stratification is used for controlling confounding variables. Since the question asks for the information that is factually incorrect.

Cephalosporin belongs to a family of beta-lactam antibiotics. All ?-lactam antibiotics interfere with the synthesis of the bacterial cell walls. The ?-lactam antibiotics inhibit the transpeptidases so that cross-linking (which maintains the close-knit structure of the cell wall) does not take place i.e. they inhibit bacterial cell wall formation.

Monosynaptic reflexes is a type of reflex arc providing direct communication between motor and sensory innervation in a muscle. It occurs very quickly as it arises and ends in the same muscle. Examples include: biceps reflex, brachioradialis reflex, extensor digitorum reflex, triceps reflex, Achilles reflex and patellar reflex.

Polysynaptic reflexes facilitates contraction and inhibition in muscle by providing communication between multiple muscles.

Sucralfate is an octasulfate of glucose to which Al(OH)3 has been added. It undergoes extensive cross-linking in an acidic environment and forms a polymer which adheres to the ulcer base for up to 6 hours and protects it from further erosion. Since it is not systemically absorbed it is virtually devoid of side effects. However, it may cause constipation in about 2% of cases due to the Aluminium component in it.

Sucralfate does not have antibacterial action against Helicobacter pylori. However, Bismuth has antibacterial action due to its oligodynamic effect.

Therapy with gabapentin requires dose adjustment with renal diseases. However, plasma monitoring of the drug is not necessary.

Gabapentin is not a liver enzyme inducer unlike other anticonvulsants like phenytoin and phenobarbitone

Gabapentin has not been shown to be associated with visual disturbances.

Gabapentin is used for add-on therapy in partial or generalized seizures and used in the management of chronic pain conditions but is of no use in petit mal.

Multiple regression analysis revealed that velocity of lactate accumulation (VOBLA) accounted for 92 percent of the variation in marathon running velocity (VM), and VOBLA plus training volume prior to the marathon accounted for 96 percent of the variation. Percent ST muscle fibre distribution (r = 0.55-0.69) and capillary density (r = 052-0.63) were found to be positively correlated with all performance variables. As a result, marathon running performance was linked to VOBLA and the ability to run at a pace close to it during the race. The percent ST, capillary density, and training volume were all related to these properties.

Another metabolic adaptation compared to normal people is the early selection of fat for oxidation by muscle, especially when glucose availability is limited during high-intensity exercise. This helps to delay the onset of muscle fatigue, but it does not prevent VOBLA.

For a given level of exercise, training can also result in cardiovascular adaptation, such as increased heart size, increased contractility, and a slower heart rate. All of these factors contribute to an increase in maximal oxygen consumption (VO2 max), but genetic factors, despite intensive training, play a large role in an athlete’s performance.

A Wrights Respirometer measures the volume of air exhaled over the course of one minute of normal breathing

It is unidirectional and measures tidal volume and minute volume of gas flow in one direction. It is placed at the expiratory side (lower pressure than inspiratory side therefore lower chances of gas leaks)

Slits are arranged such that incoming gas will rotate the vane at a rate of 150 revolutions per litre of flowing gas

The Wright respirometer tends to over-read at high flow rates and under-read at low flows because of mechanical causes like friction and inertia and the accumulation of water vapour

The ideal flow for accurate readings is 2 L/min for the respirometer. The respirometer reads the tidal volume and minute volume with a ±5–10% accuracy within the range of 4–24 L/min.

Oxygen is formed by a molecule of oxygen and two molecules of hydrogen with a molecular formula of H2O

The critical temperature is defined as a temperature above which the substance cannot be liquefied, no matter how much pressure is applied.
Water has a critical temperature of -118.6oC. So, it cannot be liquified at room temperature.

Medical oxygen cylinder is stored in a cylinder with a white shoulder and black body. Meanwhile, medial air is stored in cylinders with a white and black shoulder and a French grey body.

The partial pressure of air at a high altitude is less but the relative concentration remains constant.

The femoral triangle is a wedge-shaped area found within the superomedial aspect of the anterior thigh. It is a passageway for structures to leave and enter the anterior thigh.

Superior: Inguinal ligament
Medial: Adductor longus
Lateral: Sartorius
Floor: Iliopsoas, adductor longus and pectineus

The contents include: (medial to lateral)
Femoral vein
Femoral artery-pulse palpated at the mid inguinal point
Femoral nerve
Deep and superficial inguinal lymph nodes
Lateral cutaneous nerve
Great saphenous vein
Femoral branch of the genitofemoral nerve

Every surgical procedure is associated with a stress response which comprises a number of endocrine, metabolic, and immunological changes triggered by neuronal activation of the hypothalamic-pituitary-adrenal axis. The overall metabolic effect of the stress response to surgery includes an increase in secretion of catabolic hormones, such as cortisol and catecholamine, and a decrease in secretion of anabolic hormones, such as insulin and testosterone. The increase in levels of catabolic hormones in plasma stimulates glucose production, and there is a relative lack of insulin together with impaired tissue insulin sensitivity and glucose utilization, which is called insulin resistance. Consequently, blood glucose concentrations will increase, even in the absence of pre-existing diabetes.

A study compared the effects of spinal and general anaesthesia on changes in blood glucose concentrations during surgery in nondiabetic patients. Although mean blood glucose concentrations showed a significant proportional increase during surgery in both groups, this effect was much more significant with general anaesthesia than with spinal anaesthesia. These results indicate that spinal anaesthesia is more effective than general anaesthesia in attenuating the hyperglycaemic response to surgery.

The anterior cerebral artery supplies the midline portion of the frontal lobe and the superior medial parietal lobe of the brain. It also supplies the front four-fifths of the corpus callosum and provides blood to deep structures such as the anterior limb of the internal capsule, part of the caudate nucleus, and the anterior part of the globus pallidus.

The cerebral hemispheres are supplied by arteries that make up the Circle of Willis. The Circle of Willis is formed by the anastomosis of the two internal carotid arteries and two vertebral arteries.

Clinically, the internal carotid arteries and their branches are often referred to as the anterior circulation of the brain. The anterior cerebral arteries are connected by the anterior communicating artery. Near their termination, the internal carotid arteries are joined to the posterior cerebral arteries by the posterior communicating arteries, completing the cerebral arterial circle around the interpeduncular fossa, the deep depression on the inferior surface of the midbrain between the cerebral peduncles.

The middle cerebral artery supplies part of the frontal, temporal and parietal lobes.

The posterior cerebral artery supplies the occipital lobe.

Mapleson breathing system (or circuit) analysed five different arrangements of components of the breathing system:
Mapleson A – It is the most efficient for spontaneous respiration. The flow of fresh gas required is 70-85 ml/kg/min, i.e., approximately 5-6 lit./min fresh gas flow for an average adult.
Mapleson B and C – inefficient for both SV and PPV; requires gas flow of two to three times minute volume (100 ml/kg/min). Not commonly used but category C may be used for emergency resuscitation.
Mapleson D – efficient for PPV at gas flow equivalent to patient’s minute volume; the Bain’s circuit is a coaxial version of the Mapleson D
Mapleson E and F – for paediatric use; requires gas flow at two to three times the patient’s minute volume. The Mapleson F consists of an open-ended reservoir bag (Jackson-Rees modification).

Observation bias occurs when the behaviour of an individual changes that results from their awareness of being observed.

Recall bias introduced when participants in a study are systematically more or less likely to recall and relate information on exposure depending on their outcome status.

Attrition bias is a systematic error caused by unequal loss of participants from a randomized controlled trial (RCT). In clinical trials, participants might dropout due to unsatisfactory treatment or efficacy, intolerable adverse events, or even death.

Selection bias introduced when the individuals are not chosen randomly to take a part in the study. It usually occurs when the research decides who is going to be studied, they are not the representative of the population.

Lead-time bias occurs when a disease is detected by a screening test at an earlier time point rather than it would have been diagnosed by its clinical appearance. In this bias, earlier detection improves the survival time in the intervention group.