CRACKCast E202 – Cyanosis

Core Questions:   Define cyanosis and explain what causes it? What is central cyanosis and what typically causes it? What is peripheral cyanosis and what typically causes it? At what concentration of deoxyhemoglobin does cyanosis present? List 10 differential diagnoses for cyanosis - Box 11.2? Describe your initial workup for the patient with cyanosis.- Figure 11.3/11.4 What is the oxyhemoglobin dissociation curve and what information can be taken from it? - Figure 11.1 Name four factors that shift the oxyhemoglobin dissociation curve to the left and three factors that shift it to the right. Differentiate between ferrous and ferric hemoglobin and describe how these forms of hemoglobin affect oxygen binding. What is methemoglobinemia and how does it present? What are the two biochemical pathways that are used to reduce methemoglobin? List 10 causes of methemoglobinemia - See Box 11.1 What is sulfhemoglobinemia and when should you suspect it? Differentiate between primary, secondary, and relative polycythemia and how does it cause cyanosis?   Wisecracks:   What is the colour of the blood in a patient with methemoglobinemia? What is clubbing and what causes it? What SpO2 is present on the monitor in the patient with a methemoglobinemia? What is the hyperoxia test and how does it help you in your workup of the cyanotic patient? What is the dose of methylene blue when prescribed to treat patients with methemoglobinemia?