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  • Question 1 - A 15-day old male baby was brought to the emergency department with sweating...

    Correct

    • A 15-day old male baby was brought to the emergency department with sweating and his lips turning blue while feeding. He was born full term. On examination, his temperature was 37.9°C, blood pressure 75/45 mmHg, pulse was 175/min, and respiratory rate was 42/min. A harsh systolic ejection murmur could be heard at the left upper sternal border. X-ray chest showed small, boot-shaped heart with decreased pulmonary vascular markings. He most likely has:

      Your Answer: Tetralogy of Fallot

      Explanation:

      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.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      35.3
      Seconds

  • Question 2 - The most likely cause of prominent U waves on the electrocardiogram (ECG) of...

    Correct

    • The most likely cause of prominent U waves on the electrocardiogram (ECG) of a patient is:

      Your Answer: Hypokalaemia

      Explanation:

      The U-wave, not always visible in ECGs, is thought to represent repolarisation of papillary muscles or Purkinje fibres. When seen, it is very small and occurs after the T-wave. Inverted U-waves indicate myocardial ischaemia or left ventricular volume overload. Prominent U-waves are most commonly seen in hypokalaemia. Other causes include hypercalcaemia, thyrotoxicosis, digitalis exposure, adrenaline and class 1A and 3 anti-arrhythmic agents. It can also be seen in congenital long-QT syndrome and in intracranial haemorrhage.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      8
      Seconds

  • Question 3 - If a 70-year-old man with known atrial fibrillation dies suddenly, which of these...

    Correct

    • If a 70-year-old man with known atrial fibrillation dies suddenly, which of these is the most likely cause of death?

      Your Answer: Thromboembolism

      Explanation:

      In atrial fibrillation, the abnormal atrial contraction can cause blood to stagnate in the left atrium and form a thrombus, which may then embolize. The patient’s history of AF suggest an embolic disease, which lead to his death.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      15.8
      Seconds

  • Question 4 - For calculation of cardiac output by Fick's principle, which of the following vessels...

    Incorrect

    • For calculation of cardiac output by Fick's principle, which of the following vessels is the best source of venous blood to determine the arterial-to-venous oxygen tension difference?

      Your Answer:

      Correct Answer: Pulmonary artery

      Explanation:

      Fick’s principle states that the total uptake (or release) of a substance by peripheral tissues is equal to the product of the blood flow to the peripheral tissues and the arterial– venous concentration difference (gradient) of the substance. It is used to measure the cardiac output, and the formula is Cardiac output = oxygen consumption divided by arteriovenous oxygen difference. Assuming there are no shunts across the pulmonary system, the pulmonary blood flow equals the systemic blood flow. The arterial and venous blood oxygen content is measured by sampling from the pulmonary artery (low oxygen content) and pulmonary vein (high oxygen content). Peripheral arterial blood is used as a surrogate for the pulmonary vein.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 5 - A 13 year old girl presented with signs of shortness of breath, chest...

    Incorrect

    • A 13 year old girl presented with signs of shortness of breath, chest pain, non-productive cough, oedema of the lower extremities and cyanosis of the fingertips. She has a history of a ventricular septal defect not surgically corrected. The most probable cause of these symptoms is:

      Your Answer:

      Correct Answer: Shunt reversal

      Explanation:

      A ventricular septal defect (VSD) is a common form of congenital heart defects and is characterised by the presence of a hole in the wall that separates the right from the left ventricle. Medium or large defects can cause many complications. One of these complication is Eisenmenger syndrome, characterised by reversal of the shunt (from left-to-right shunt into a right-to-left) ,cyanosis and pulmonary hypertension.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      0
      Seconds

  • Question 6 - A 55-year-old woman died 3 years after a cardiac transplant due to worsening...

    Incorrect

    • A 55-year-old woman died 3 years after a cardiac transplant due to worsening congestive heart failure. Autopsy revealed diffuse hyperplasia of the vascular intima involving the entire length of the coronary arteries. The most probable cause of deterioration of the cardiac function is:

      Your Answer:

      Correct Answer: Coronary atherosclerosis

      Explanation:

      Allograft coronary artery disease (CAD) can begin right after the transplant and is the major cause of later death in cardiac transplant recipients. This form of atherosclerosis progresses quickly resulting in allograft failure. Due to lack of premonitory symptoms CAD may lead to sudden death.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      0
      Seconds

  • Question 7 - Calculate the resistance of the artery if the pressure at one end is...

    Incorrect

    • Calculate the resistance of the artery if the pressure at one end is 60 mmHg, pressure at the other end is 20 mm Hg and the flow rate in the artery is 200 ml/min.

      Your Answer:

      Correct Answer: 0.2

      Explanation:

      Flow in any vessel = Effective perfusion pressure divided by resistance, where effective perfusion pressure is the mean intraluminal pressure at the arterial end minus the mean pressure at the venous end. Thus, in the given problem, resistance = (60 − 20)/200 = 0.2 mmHg/ml per min.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 8 - Purkinje fibres in the heart conduct action potentials at the rate of: ...

    Incorrect

    • Purkinje fibres in the heart conduct action potentials at the rate of:

      Your Answer:

      Correct Answer: 1.5–4.0 m/s

      Explanation:

      Purkinje fibres control the heart rate along with the sinoatrial node (SA node) and the atrioventricular node (AV node). The QRS complex is associated with the impulse passing through the Purkinje fibres. These fibres conduct action potential about six times faster than the velocity in normal cardiac muscle.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 9 - A new-born was found to have an undeveloped spiral septum in the heart....

    Incorrect

    • A new-born was found to have an undeveloped spiral septum in the heart. This is characteristic of which of the following?

      Your Answer:

      Correct Answer: Persistent truncus arteriosus

      Explanation:

      Persistent truncus arteriosus is a congenital heart disease that occurs when the primitive truncus does not divide into the pulmonary artery and aorta, resulting in a single arterial trunk. The spiral septum is created by fusion of a truncal septum and the aorticopulmonary spiral septum. Incomplete development of these septa results in incomplete separation of the common tube of the truncus arteriosus and the aorticopulmonary trunk.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      0
      Seconds

  • Question 10 - When does the heart rate decrease? ...

    Incorrect

    • When does the heart rate decrease?

      Your Answer:

      Correct Answer: Pressure on the eyeball

      Explanation:

      Various vagotonic manoeuvres (e.g. Valsalva manoeuvre, carotid sinus massage, pressure on eyeballs, ice-water facial immersion, swallowing of ice-cold water) result in increased parasympathetic tone through the vagus nerve which results in a decrease in heart rate. These manoeuvres may be clinically useful in terminating supraventricular arrhythmias.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 11 - A 40 year old man suffered severe trauma following a MVA. His BP...

    Incorrect

    • A 40 year old man suffered severe trauma following a MVA. His BP is 72/30 mmhg, heart rate of 142 beats/mins and very feeble pulse. He was transfused 3 units of blood and his BP returned to 100/70 and his heart rate slowed to 90 beats/min. What decreased after transfusion?

      Your Answer:

      Correct Answer: Total peripheral resistance

      Explanation:

      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

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 12 - If the blood flow is constant, oxygen extraction by tissues will show the...

    Incorrect

    • If the blood flow is constant, oxygen extraction by tissues will show the greatest decrease due to which of the following interventions?

      Your Answer:

      Correct Answer: Tissue cooling

      Explanation:

      With a constant blood flow to a given tissue bed, there will be an increase in oxygen extraction by the tissue with the following; an increase in tissue metabolism and oxygen requirements: warming (or fever), exercise, catecholamines and thyroxine. With cooling, the demand for oxygen decreases, leading to decreased oxygen extraction.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 13 - Calculate the stroke volume in an adult male with the following parameters:

    Heart...

    Incorrect

    • Calculate the stroke volume in an adult male with the following parameters:

      Heart rate 70 beats/min

      Arterial [O2] 0.24 ml O2/min

      Venous [O2] 0.16 ml O2/mi

      Whole body O2 consumption 500 ml/min

      Pulmonary diastolic pressure 15 mmHg

      Pulmonary systolic pressure 25 mmHg

      Wedge pressure 5 mmHg.

      Your Answer:

      Correct Answer: 90 ml

      Explanation:

      Fick’s principle states that, VO2 = (CO × CAO2) – (CO × CVO2) where VO2 = oxygen consumption, CO = cardiac output, CAO2 = oxygen concentration of arterial blood and CVO2 = oxygen concentration of venous blood. Thus, CO = VO2/CAO2– CVO2, CO = 500/0.24–0.16, CO = 500/0.8, CO = 6.25 l/min. Cardiac output is also given by product of stroke volume and heart rate. Thus, stroke volume = cardiac output / heart rate = 6.25/70 × 1000 stroke volume = 90 ml approximately.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 14 - Calculate the stroke volume in a patient admitted for coronary bypass surgery, with...

    Incorrect

    • Calculate the stroke volume in a patient admitted for coronary bypass surgery, with the following parameters pre-operatively:

      Oxygen consumption = 300 ml/min

      Arterial oxygen content = 20 ml/100 ml blood

      Pulmonary arterial oxygen content = 15 ml/100 ml blood and Heart rate = 100 beats/min.

      Your Answer:

      Correct Answer: 60 ml

      Explanation:

      By Fick’s principle, cardiac output can be calculated as follows: VO2 = CO × (CAO2– CVO2) where VO2= oxygen consumption, CO = cardiac output, CAO2 = arterial oxygen content and CvO2 = mixed venous oxygen content. Thus, in the given problem, 300 ml/min = CO × (20 – 15) ml/100 ml CO = 300 × 100/5 ml/min CO = 6000 ml/min. Also, cardiac output = stroke volume × heart rate. Thus, 6000 ml/min = stroke volume × 100 beats/min. Hence, stroke volume = 6000/100 ml/min which is 60 ml/min.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 15 - What percentage of the cardiac output is delivered to the brain? ...

    Incorrect

    • What percentage of the cardiac output is delivered to the brain?

      Your Answer:

      Correct Answer: 15%

      Explanation:

      Among all body organs, the brain is most susceptible to ischaemia. Comprising of only 2.5% of total body weight, the brain receives 15% of the cardiac output. Oxygen extraction is also higher with venous oxygen levels approximating 13 vol%, and arteriovenous oxygen difference of 7 vol%.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 16 - Which of the following is the cause of flattened (notched) T waves on...

    Incorrect

    • Which of the following is the cause of flattened (notched) T waves on electrocardiogram (ECG)?

      Your Answer:

      Correct Answer: Hypokalaemia

      Explanation:

      The T-wave is formed due to ventricular repolarisation. Normally, it is seen as a positive wave. It can be normally inverted (negative) in V1 (occasionally in V2-3 in African-Americans/Afro-Caribbeans). Hyperacute T-waves are the earliest ECG change of acute myocardial infarction. ECG findings of hyperkalaemia include high, tent-shaped T-waves, a small P-wave and a wide QRS complex. Hypokalaemia results in flattened (notched) T-waves, U-waves, ST-segment depression and prolonged QT interval.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 17 - What is the normal duration of the ST segment? ...

    Incorrect

    • What is the normal duration of the ST segment?

      Your Answer:

      Correct Answer: 0.08 s

      Explanation:

      The ST segment lies between the QRS complex and the T-wave. The normal duration of the ST segment is 0.08 s. ST-segment elevation or depression may indicate myocardial ischaemia or infarction.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 18 - In a cardiac cycle, what event does the closing of atrioventricular (AV) valves...

    Incorrect

    • In a cardiac cycle, what event does the closing of atrioventricular (AV) valves coincide with?

      Your Answer:

      Correct Answer: First heart sound

      Explanation:

      In the cardiac cycle, the closing of the atrioventricular (AV) valves coincides with the onset of ventricular systole. This event marks the beginning of the isovolumetric contraction phase, where the ventricles begin to contract, but the volume of blood in the ventricles remains the same because both the AV valves and the semilunar valves (aortic and pulmonary valves) are closed. The closing of the AV valves produces the first heart sound, known as “S1” or “lub.”

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 19 - Calculate the total peripheral resistance for a patient with a blood pressure of...

    Incorrect

    • Calculate the total peripheral resistance for a patient with a blood pressure of 130/70 mm HG and cardiac output of 5 litres / min?

      Your Answer:

      Correct Answer: 18 mmHg × min/l

      Explanation:

      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.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 20 - QT interval in the electrocardiogram of a healthy individual is normally: ...

    Incorrect

    • QT interval in the electrocardiogram of a healthy individual is normally:

      Your Answer:

      Correct Answer: 0.40 s

      Explanation:

      QT interval extends from beginning of the QRS complex till the end of he T-wave and normally lasts for 0.40 s. It is important in the diagnosis of long-QT and short-QT syndrome. The QT interval varies on the basis of heart rate and may need to be corrected.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 21 - A 34-year-old woman with severe burns, presented to casualty with a blood pressure...

    Incorrect

    • A 34-year-old woman with severe burns, presented to casualty with a blood pressure of 75/40 mmHg and pulse of 172/minute. Obviously the patient is in shock. Which type of shock is it more likely to be?

      Your Answer:

      Correct Answer: Hypovolaemic shock

      Explanation:

      Shock is a life-threatening condition that occurs when the organs and tissues of the body are not receiving a sufficient flow of blood. Lack of blood flow, oxygen and nutrients results in the inability to function properly and damage to many organs. Shock requires immediate treatment because, if left untreated the impaired tissue perfusion and cellular hypoxia can cause irreversible tissue injury, collapse, coma or even death. There are various types of physiological shock, including: cardiogenic (due to heart damage), hypovolaemic (due to low total volume of blood or plasma), neurogenic (due to nervous system damage), septic (due to infections) and anaphylactic shock (due to allergic reactions). Hypovolaemic shock can be caused by blood loss due to trauma, internal bleeding or other fluid loss due to severe burns, prolonged diarrhoea, vomiting and sweating.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      0
      Seconds

  • Question 22 - Which of the following is responsible for the maximum increase in total peripheral...

    Incorrect

    • Which of the following is responsible for the maximum increase in total peripheral resistance on sympathetic stimulation?

      Your Answer:

      Correct Answer: Arterioles

      Explanation:

      Arterioles are also known as the resistance vessels as they are responsible for approximately half the resistance of the entire systemic circulation. They are richly innervated by the autonomic nervous system and hence, will bring about the maximum increase in peripheral resistance on sympathetic stimulation.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 23 - A 30 year old man suffered severe blood loss, approx. 20-30% of his...

    Incorrect

    • A 30 year old man suffered severe blood loss, approx. 20-30% of his blood volume. What changes are most likely seen in the pulmonary vascular resistance (PVR) and pulmonary artery pressure (PAP) respectively following this decrease in cardiac output?

      Your Answer:

      Correct Answer: Increase Decrease

      Explanation:

      Hypovolemia will result in the activation of the sympathetic adrenal discharge resulting is a decrease pulmonary artery pressure and an elevated pulmonary vascular resistance.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 24 - Calculate the cardiac output of a patient with the following measurements: oxygen uptake...

    Incorrect

    • Calculate the cardiac output of a patient with the following measurements: oxygen uptake 200 ml/min, oxygen concentration in the peripheral vein 7 vol%, oxygen concentration in the pulmonary artery 10 vol% and oxygen concentration in the aorta 15 vol%.

      Your Answer:

      Correct Answer: 4000 ml/min

      Explanation:

      The Fick’s principle states that the uptake of a substance by an organ equals the arteriovenous difference of the substance multiplied by the blood flowing through the organ. We can thus calculate the pulmonary blood flow with pulmonary arterial (i.e., mixed venous) oxygen content, aortic oxygen content and oxygen uptake. The pulmonary blood flow, systemic blood flow and cardiac output can be considered the same assuming there are no intracardiac shunts. Thus, we can calculate the cardiac output. Cardiac output = oxygen uptake/(aortic − mixed venous oxygen content) = 200 ml/min/(15 ml O2/100 ml − 10 ml O2/100 ml) = 200 ml/min/(5 ml O2/100 ml) = 200 ml/min/0.05 = 4000 ml/min.

      It is crucial to remember to use pulmonary arterial oxygen content and not peripheral vein oxygen content, when calculating the cardiac output by Fick’s method.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 25 - Calculate the cardiac stroke volume of a patient whose oxygen consumption (measured by...

    Incorrect

    • Calculate the cardiac stroke volume of a patient whose oxygen consumption (measured by analysis of mixed expired gas) is 300 ml/min, arterial O2 content is 20 ml/100 ml blood, pulmonary arterial O2 content is 15 ml/100 ml blood and heart rate is 60/min.

      Your Answer:

      Correct Answer: 100 ml

      Explanation:

      By Fick’s principle, VO2 = Q × (CA (O2) − CV (O2)) where VO2 = O2 consumption, Q = cardiac output and CA(O2) and CV(O2) are arterial and mixed venous O2 content respectively. Thus, in the given problem, 300 ml O2/min = Q × (20−15) ml O2/100 ml. Thus, Q = 6000 ml blood/min. Then, we can calculate stroke volume by dividing the cardiac output with heart rate. Thus, stroke volume = 6000 ml/min divided by 60/min stroke volume = 100 ml.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 26 - As per the Poiseuille-Hagen formula, doubling the diameter of a vessel will change...

    Incorrect

    • As per the Poiseuille-Hagen formula, doubling the diameter of a vessel will change the resistance of the vessel from 16 peripheral resistance units (PRU) to:

      Your Answer:

      Correct Answer: 1 PRU

      Explanation:

      Poiseuille-Hagen formula for flow in along narrow tube states that F = (PA– PB) × (Π/8) × (1/η) × (r4/l) where F = flow, PA– PB = pressure difference between the two ends of the tube, η = viscosity, r = radius of tube and L = length of tube. Also, flow is given by pressure difference divided by resistance. Hence, R = 8ηL ÷ Πr4. Hence, the resistance of the vessel changes in inverse proportion to the fourth power of the diameter. So, if the diameter of the vessel is increased to twice the original, it will lead to decrease in resistance to one-sixteenth its initial value.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 27 - What percentage of cardiac output is delivered to the skin? ...

    Incorrect

    • What percentage of cardiac output is delivered to the skin?

      Your Answer:

      Correct Answer: 2%

      Explanation:

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

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 28 - Decreased velocity of impulse conduction through the atrioventricular node (AV node) in the...

    Incorrect

    • Decreased velocity of impulse conduction through the atrioventricular node (AV node) in the heart will lead to:

      Your Answer:

      Correct Answer: Increased PR interval

      Explanation:

      AV node damage may lead to an increase in the PR interval to as high as 0.25 – 0.40 s (normal = 0.12 – 0.20 s). In the case of severe impairment, there might be a complete failure of passage of impulses leading to complete block. In this case, the atria and ventricles will beat independently of each other.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 29 - A 45-year-old man presents to the emergency department with an irregular pulse and...

    Incorrect

    • A 45-year-old man presents to the emergency department with an irregular pulse and shortness of breath. Electrocardiography findings show no P waves, normal QRS complexes and an irregularly irregular rhythm. The patient most probably has:

      Your Answer:

      Correct Answer: Atrial fibrillation

      Explanation:

      Atrial fibrillation is one of the most common arrhythmias, characterised by an irregular and rapid heart rate. Due to the decreased cardiac output, atrial fibrillation increases the risk of heart failure. It can also lead to thrombus formation which may lead to thromboembolic events. Clinical findings include palpitations, shortness of breath, fatigue, chest pain and confusion. The diagnosis is made by electrocardiographic findings which include absent P wave, fibrillatory (f) waves between QRS complexes and irregularly irregular R-R intervals.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      0
      Seconds

  • Question 30 - Calculate the pulmonary vascular resistance in an adult male with the following parameters:...

    Incorrect

    • Calculate the pulmonary vascular resistance in an adult male with the following parameters:

      Heart rate 70 beats/min

      Arterial [O2] 0.24 ml O2/min

      Venous [O2] 0.16 ml O2/mi

      Whole body O2 consumption 500 ml/min

      Pulmonary diastolic pressure 15 mmHg

      Pulmonary systolic pressure 25 mmHg

      Wedge pressure 5 mmHg.

      Your Answer:

      Correct Answer: 2.0 resistance units (mmHg/l per min)

      Explanation:

      Pulmonary vascular resistance (PVR) = (Mean pulmonary artery pressure – Pulmonary capillary wedge pressure) divided by Cardiac output. To get cardiac output, Fick’s principle needs to be applied which states that VO2 = (CO × CAO2) – (CO × CVO2) where VO2 = oxygen consumption, CO = cardiac output, CA = oxygen concentration of arterial blood and CVO2 = oxygen concentration of venous blood. Thus, CO = VO2/CAO2– CVO2, CO = 500/0.24–0.16, CO = 500/0.8, CO = 6.25 l/min. To calculate mean pulmonary artery pressure, we use the formula: Mean pulmonary artery pressure = Diastolic pressure + 1/3(Systolic pressure – Diastolic pressure). Thus, Mean pulmonary artery pressure = 15 + 1/3(25 – 15) = 15 + 3. 33 = 18.33. Substituting these values in the first formula, PVR = 18.3–5/6.25 = 13.5/5.25 = 2.0 resistance units (mmHg/l per min) approximately.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

SESSION STATS - PERFORMANCE PER SPECIALTY

Cardiovascular (3/3) 100%
Physiology (2/2) 100%
Pathology (1/1) 100%
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