Anaesthesia and SCD – Category 2

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The Haemoglobin Molecule
Tetramer consisting of 2α and 2β chains. Each chain enfolding a haem moeity. Oxygen reversibly binds to the ferric(Fe2+) iron molecule.

Exterior is highly polar (water soluble), whilst interior hydrophobic.

Most important purpose = oxygen transport.

Genotypes --> HbA;2α2β, HbA2;2 α2δ, HbF;2 α 2 ϒ

Normal concentrations HbA – 95%, HbA2 – 2.5%, HbF – 2.5%
- One oxygen molecule
- Two oxygen molecules
- Three oxygen molecules
- Four oxygen molecules
- Five oxygen molecules
Question Knowledge Base
Haemoglobin is a tetramer with 4 haem moeity’s, oxygen binds to each of the iron molecules. Hence 4 molecules of oxygen will bind to each molecule of haemoglobin.
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The defect in SCD
Which is the correct statement regarding causes of a RIGHT shift in the oxygen dissociation curve?
- Increased 2,3 DPG, increased pH, hypothermia, increased HbF
- Increased 2,3 DPG, reduced pH, hyperthermia, reduced HbF
- Increased 2,3 DPG, increased pH, hyperthermia, reduced HbF
- Reduced 2,3 DPG, reduced pH, hypothermia, reduced HbF
- Increased 2,3 DPG, reduced pH, hypothermia, increased HbF
Question Knowledge Base
Source: West JB, Respiratory Physiology: The Essentials. 7th Ed. Lippincott Williams & Wilkins 2005. Maryland USA.
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What is the estimated prevalence of sickle cell trait in Nigeria?
- 1.5%
- 5%
- 8%
- 15%
- 19.4%
Question Knowledge Base
Source: Umoh AV, Abah GM, Ekanem TI and Essien EM. Haemoglobin genotypes: a prevalence study and implications for reproductive health in Uyo, Nigeria. Niger J Med. 2010;19(1):36-41.
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Regions of birth, Proportion of Australia's population - Selected years at 30 June
Which area is responsible for most of the 5 spontaneous mutations of the sickle haemoglobin allele?
- Asian subcontinent
- The Mediterranean
- Middle East
- Africa
- South-East Asia
Question Knowledge Base

Source: Antonarakis SE, Boehm CD, Serjeant GR, et al. Origin of the beta S-globin gene in blacks: the contribution of recurrent mutation or gene conversion or both. Proc Natl Acad Sci U S A 1984;81(3):853–6.
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According to the CSSCD which genotype is most likely to suffer Painful crises (vaso-occlusive crises)?
- HbSS
- HbS/βo thalassemia
- HbS/β+ thalassemia
- HbAS
- HbSC
Question Knowledge Base

Source: Platt O, Thorington BD, Brambilla DJ, Milner PF, Rosse W, Vichinsky E, et al. Pain in sickle cell disease: rates and risk factors. New Engl J Med 1991;325:11–6.
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In sickle cell trait, about what proportion of haemoglobin is HbS?
- 10-20%
- 20-30%
- 30-40%
- 40-50%
- 50-60%
Question Knowledge Base

Source: Wilson M, Forsyth P, Whiteside J. Haemoglobinopathy and sickle cell disease. Continuing Education in Anaesthesia, Critical Care and Pain 2010;Volume 10 Number 1; 24-28.
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Which of the following is NOT an indication for Bone Marrow Transplantation in an SCD patient with an identical sibling donor?
- Sickle nephropathy
- Congestive Cardiac Failure with an Ejection Fraction < 30%
- Acute Chest syndrome with a history of recurrent hospitalizations or exchange transfusions
- Bilateral proliferative retinopathy and major visual impairment in at least 1 eye
- Impaired neuropsychological function and abnormal cerebral MRI scan
Question Knowledge Base

Source: Smiers FJ, Krishnamurti L, Lucarelli G. Hematopoietic Stem Cell Transplantation for Hemoglobinopathies: Current Practice and emerging trends. Pediatr Clin N Am 2010;57:181-205.
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Which statement regarding pulse oximetry is most true in SCD?
- Overestimates true SpO2 by 2%
- Overestimates true SpO2 by 4%
- Underestimates true SpO2 by 2%
- Underestimates true SpO2 by 4%
- Essentially correct SpO2
Question Knowledge Base

Source: Fitzgerald RK, Johnson A. Pulse oximetry in sickle cell anemia. Crit Care Med 2001;29(9):1803–6.
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Which of the following is not a statistically significant difference between SCD parturients and non-SCD parturients?
- SCD has a higher rate of eclampsia
- SCD has a higher rate of anaemia
- SCD has a higher rate of chest infections
- SCD has a higher rate of pregnancy induced hypertension
- SCD has a higher rate of severe pre-eclampsia
Question Knowledge Base

Source: Al Jama FE et al. Pregnancy outcome in patients with homozygous SCD in a university hospital, Eastern Saudi Arabia. Arch Gynecol Obstet 2009; 280:793-797.
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Which of the following is NOT a risk factor for osteonecrosis of the femoral heads in SCD?
- Frequent painful crises
- History of stroke
- High hematocrit
- Lower Mean Corpuscular Volume (MCV)
- Lower Aspartate Transaminase (AST)
Question Knowledge Base

Source: Milner PF, Kraus AP, Sebes JI, Sleeper LA, Dukes KA, Embury SH, et al. Sickle cell disease as a cause of osteonecrosis of the femoral head. New Engl J Med 1991;325:1476–81.
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Which of the following is NOT a risk factor for early death in SCD?
- More symptomatic disease
- A lower HbF level
- A white cell count > 15,000/ml3
- Haemoglobin <7.1g/dL
- Haemoglobin > 10.0g/dL
Question Knowledge Base

Source: Platt OS, Brambilla DJ, Rosse WF, Milner PF et al. Mortality in sickle cell disease, life expectancy and risk factors for early death. N Engl J Med 1994;330(23):1639-44.
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