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Peak Flow Normal Limits


Hi guys, I hope somebody can help.

I've applied to join the RN as X(SM) Officer and have so far completed endless forms (including DV form), Psychometric tests & Sift Interview. I had my medical at the beginning of March and everything was absolutely fine except for my peak flow reading.

I was suffering from the tail-end of a cold on the day, but even still my reading was little over 400 L/min. The Medical Officer did as was expected and sent me away to keep a peak flow diary for a month, which I have been doing and I go back for a review a week on Tuesday.

I did suffer from Asthma as a child, up until I was about 6 or 7, but nothing since. I've not smoked a cigarette in my life and I keep myself fit.

I'm 24 years old, Caucasian, 182cm tall, and weigh 78kg. Yet my average reading is only 520 L/min and my highest reading only 550. According to the chart on their website I should be getting readings of around 620L/min.

The website does state: "In men, readings up to 100 L/min lower than predicted are within normal limits. For women, the equivalent figure is 85
L/min. Values are derived from Caucasian populations."

My question is whether the Medical Officers take this into consideration when assessing whether you are fit to pass or not? If they do then I am still within NORMAL limits which is great. If not, then it's Game Over.

I've searched both RR and external sites for an answer but with no luck. I am hoping someone on here will know the answer and give me good news!

Thanks in advance.


War Hero
I should think that the Medical professionals in the RN are more than aware of the possible discrepencies that can occur and will take that into account.

Angry Doc, an RN Medical Officer and RR MOD will be along directly, to offer advice.


War Hero
Book Reviewer
NZ_Bootneck said:
I should think that the Medical professionals in the RN are more than aware of the possible discrepencies that can occur and will take that into account.

Angry Doc, an RN Medical Officer and RR MOD will be along directly, to offer advice.

And to offer; "Take a week's brufen, if it still hurts come back".


War Hero
When I had my peak flow measured recently, I registered off the scale (the meter went up to 800). The MA couldn't believe it, and made me do it again. Again, I got over the 800 mark. Finally, a POMA (Scotty) was called, just to double check. This time, I managed almost exactly 800. For the record, I am caucasian, 184cm tall, and (at the time of the test) aged 45.


Just goes to show then just how varied people's readings can be. Would far rather my reading was like your's than mine though!


Sorry for the delay- was on an AngryHoliday.

We take a margin of error in all quantitative readings- don't worry. As long as the diary reflects your peak flow stays where it is and doesnt dip much lower there'll not be a prob. Not sure why your readings are a bit low though. At the end of the day, all physiological values follow a normal distribution curve- you might just be in the 5% at the left side.

(not going to bite wrt the brufen thing by the way)


Thanks for the reply angrydoc it's much appreciated. My medical is on Tuesday and I'm pretty nervous (I hope this doesn't affect my reading!) as I really want to pass. My readings are averaging mid 500's although there is a visible gradient of improvement, which I can only put down to technique.

Let's just hope my lungs perform on the day. Thanks again.

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