Principles of flow

Question 1

list the peak flow equiptment

Answer 1

-peak flow meter
-disposable mouthpiece , with one way valves or BVF
- one way safety valve prevents patients breathing in equiptment
-reduces infection risk
-valve should face patient

Question 2

How do we measure peak flow?

Answer 2

-attach mouthpiece ot peak flow meter
-move pointer on meter to 0
-ask patient to breath in to TLC, put mouthpiece into mouth
-make sure peak flow meter remains horizontal and the patient does not occlude the scale or pointer
-short, sharp puff
-remove peak flow meter, record value
-reset pointer
-repeat x2
-report best attempt of 3

Question 3

What are some errors of measurements?

Answer 3

-poor effort
-leaks around the mouthpiece
-inadequate rest between attempts
-fingers occluding the pointer on the peak flow meter

Question 4

What is sequential peak flow monitoring?

Answer 4

-recording peak flow over a period of time can be used to aid diagnosis

-patients typically record their peak flow 2-4 times a day and record results in a peak flow diary for at least 2 weeks

Question 5

What is some variablility involved in Peak flow?

Answer 5

-normal diurnal variation in peak flow is 8%
-variation less that or equal to 20% indicates asthma

Question 6

How is variability calculated?

Answer 6

%change = max PEF-min PEF x100
divided by max PEF

Question 7

What are some limitations of peak flow?

Answer 7

-PEF is effort dependent
-patients are likely to comply with PEF over a short time rather than long time measurements
-patients can produce high measurements by coughing or spitting into the meter
-patients can falsify results
-if patients dont clean the peak flow meter moisture can build up and cause errors in measurements