Transition Block 1

Question 1

Changes in carbon dioxide, temperature and pH can cause shifts in the oxygen saturation curve. Which of the following options correctly describes an environment where there is a right shift of this curve?

-pulmonary venous blood in patient with thalassemia
-pulmonary venous blood in a patient after strenuous exercise
-systemic arterial blood pressure from a patient who just recieved a large infusion of blood
-systemic arterial blood in a normal patient at rest
-pulmonary arterial blood of an athlete who just finished running a marathon at sea level

Answer 1

Oxygen dissociation curve moving to the right means haemoglobin has a decreased affinity for oxygen
BOHR EFFECT: oxygen dissociation curve moves to the right, examples include after aerobic exercise

Question 2

A 68-year-old patient presents to Accident and Emergency following a two week history of productive cough, fever and shortness of breath. The patient has had a similar episode of these symptoms two years ago, which required a hospital admission.

Observations are taken and are recorded as follows:

HR: 104bpm
RR: 25
BP: 100/72 mmHg
SpO2: 91% on air
Temp: 38.5C
What is the next best investigation to carry out?

-bronchoalveloar lavage
-sputum culture
-peak flow reading
-arterial blood gas
-full blood count

Answer 2

Question 3

A patient has COPD. Their ABG reading shows CO2 retention.

What effect would this have on the oxygen dissociation curve?

Answer 3

The curve shifts to the right due to hypercapnia (haemoglobin has an increased affinity for oxygen)