What is spirometry?

Patient Background
You have been tasked Priority 2 to a 75 year old man with chest tightness and shortness of breath. On your arrival you find a very thin, elderly man sitting on a chair with his arms braced on his knees. He looks very dyspnoeic. His initial observations are:
Respiratory rate 45 breaths/minute
Heart rate 120 beats/minute
Blood Pressure 95/50 mmHg
Oxygen saturation 82%
Glasgow Coma Score 13 (E=3,V=4, M=6)
The man’s name is Mr Wenham, and he is only able to speak single words. His wife tells you that his breathing is never very good, because he smoked far too much. She says he sometimes struggles to walk around the house.
Symptoms Shortness of breath, chest tightness, cough
Onset “His breathing has been particularly bad for the last two days and much worse for the last hour or so”
Chest examination Barrel chested, little chest wall movement
Breathing sounds Very quiet breath sounds, occasional wheeze
Jugular veins Elevated 5cm
You form the view that Mr Wenham is suffering from an exacerbation of Chronic Obstructive Pulmonary Disease (COPD). You administer supplemental oxygen, atrovent and salbutamol (following local guidelines), and prepare for the 60 minute journey to hospital.
Describe the underlying pathology of COPD and the common pathological characteristics of the condition. Discuss the impact these pathological changes have on normal function, including how alveolar ventilation might be different in Mr Wenham compared to a normal individual.(20 marks)
Discuss why you would administer salbutamol and describe how it works at the cellular level.(10 marks)
Mr Wenham’s oxygen saturation improves with supplemental oxygen but he remains tachypnoeic, tachycardic and hypotensive. On arrival at the Emergency Department you go straight to the resuscitation room and an arterial blood gas sample is taken and analysed immediately with the following results:
pH 7.12
PaO2 100 mmHg.
PaCO2 110 mmHg
HCO3 38
Discusswhy they would take an arterial blood gas and explain what the results mean and how they relate to the pathophysiology you described.(10 marks)
The emergency department staffsuggest you may have given Mr Wenham too much oxygen. They say they are going to remove the oxygen.
Overview the normal physiological control of breathing. Then, identify and discuss the issues surrounding the use of supplemental oxygen therapy in patients with severe exacerbations of COPD. What problems can it cause and why? (20 marks)
When considering his blood gas analysis, do you think it is a good idea to remove Mr Wenham’s oxygen and have him just breathing air? Provide an argument supporting why it is OR why it is not.(10 marks)
The emergency department consultant returns from his lunch break to interrupt the oxygen debate. He suggests that Mr Wenham needs BiPAP.
What is BiPAP? How might BiPAP help to improve Mr Wenham’s clinical condition? (10 marks)
Three days later, after 18 hours of BiPAP, corticosteroids and physiotherapy, Mr Wenham is much improved. The respiratory physician responsible for his care orders spirometry. This shows:
FEV1 0.75 litres
FVC 1.5 litres
FEV1/FVC 50%
What is spirometry? (5 marks)
Discuss the significance of the results by examining the differences between Mr Wenham’s spirometry and that of a normal individual? (10 marks)
How does the pathology of COPD explain these differences? (5 marks)
Integrated Clinical Case
Answer Template (cut and paste into a new document).
Describe the underlying pathology of COPD and the common pathological characteristics of the condition. Discuss the impact these pathological changes have on normal function, including how alveolar ventilation might be different in Mr Wenham compared to a normal individual. (20 marks)
Discuss why you would administer salbutamol and describe how it works at the cellular level. (10 marks)
Discuss why they would take an arterial blood gas and explain what the results mean and how they relate to the pathophysiology you described. (10 marks)
Overview the normal physiological control of breathing. Then, identify and discuss the issues surrounding the use of supplemental oxygen therapy in patients with severe exacerbations of COPD. What problems can it cause and why? (20 marks)
When considering his blood gas analysis, do you think it is a good idea to remove Mr Wenham’s oxygen and have him just breathing air? Provide an argument supporting why it is OR why it is not.(10 marks)
What is BiPAP? How might BiPAP help to improve Mr Wenham’s clinical condition? (10 marks)
What is spirometry? (5 marks)
Discuss the significance of the results by examining the differences between Mr Wenham’s spirometry and that of a normal individual. (10 marks)
How does the pathology of COPD explain these differences? (5 marks)