SNIP when you can’t MIP

The MIP test is used to assess the strength of the inspiratory muscles and is commonly performed in patients with neuromuscular disease. Results however, are often low because the sensation involved in performing a maximal inspiratory effort against an occluded airway is unpleasant and because the MIP requires coordination, cooperation and motivation to be performed correctly. In addition patients with neuromuscular disease frequently lack the muscular strength necessary to grip the mouthpiece and can therefore leak around it. For these reasons although a normal value will rule out significant muscular weakness, a low value can be difficult to interpret.

Sniff Nasal Inspiratory Pressure (SNIP) is an alternative way to measure inspiratory muscle strength that does not require a mouthpiece and uses a fairly natural maneuver. To perform the test one nostril is blocked with a soft probe attached to either a manometer or a transducer. The patient is asked to perform a normal exhalation to FRC and then inhale forcibly (sniff) with their mouth closed. The sniff effort is short since the maximum nasal inspiratory pressure is reached in a half a second or less.

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What’s normal about a 6-minute walk?

The distance attained during a 6-minute walk (6MWD) has been used extensively to assess the functional capacity of patients with a variety of diseases and conditions. It is relatively easy to perform and requires a minimum of equipment. Changes in 6MWD before and after rehabilitation, surgery, or medications are often used to signal the success or failure of these therapies. For the last dozen years every drug and device research study my lab has been involved with has used the 6MWD as one of their outcomes.

The 6-minute walk distance has been noted to depend on the age, gender, height and weight of the individual. There are, however, relatively few studies to choose from when it comes to selecting normal values for the 6MWD and each of these studies differs not only in the degree of importance it assigns to these variables but in the predicted 6MWD. Despite the clinical significance of changes in the 6-minute walk distance it is far from clear what a normal 6-minute walk distance actually is.

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When spirometry was amusing

The late 1800’s through the early 1900’s saw the birth and spread of amusement parks, penny arcades and nickelodeons. Although this was due in part to an increase in the number of people living in cities and to an increase in disposable income, it was also in large part due to the invention of mass transit. In a bid to increase ridership many railroad, trolley and subway lines built or sponsored amusement parks.

At the amusement parks, along with the carousels, ferris wheels and roller coasters there was the penny arcade and in amongst the penny arcade’s slot machines, strength testers, music machines, scales, gumball machines and electric shockers were the coin-operated spirometers. Coin operated spirometers started off with simple dials and quickly became elaborate amusements unto themselves.


A coin-operated spirometer from the National Spirometer Company from around 1900.

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Marketing your PFT Lab

A writer posed an interesting question on the AARC Diagnostics forum several weeks ago and that was how to market their PFT Lab. I don’t think they got much of a response but I have been thinking about this since then.

I think that any good lab manager wants to see their lab succeed and grow. I’ve always felt that pulmonary function testing is an essential component of preventive care but that despite this PFT Labs are underutilized. In order to market your PFT Lab effectively you need to understand your customers and target your message accordingly. You also need to understand that you can’t get something for nothing. Marketing requires that you expend resources, whether it is just your time or includes lab budget money, in order to get any payback.

There are three target audiences for your marketing; patients, physicians and administrators. Each audience has a different question you must be able to answer. For patients the question is going to be “why do I need pulmonary function testing?”. For physicians it is going to be “why should I send my patients to your lab?” and for administrators it is “why should I devote resources to your lab?”.

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