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1.2

Major VersionM

by Procheta Mallik

Introduction

Estimation of lung capacity using a 2m-long polythene bag by tying a knot at one end and blowing air at the other end. The air blown into the polythene bag is the measure of one's lung capacity, which is estimated using a water bottle as a measuring tool.

Video Overview

  1. Take a thin polythene bag of about 2m length. Tie a rigid knot at one end of the bag to seal it from that end. "Closed" end.
    • Take a thin polythene bag of about 2m length.

    • Tie a rigid knot at one end of the bag to seal it from that end.

    • "Closed" end.

    • "Open" end.

  2. Place the open end of the bag around your mouth in such a way that air won't escape when you blow. Now, take a deep breath and blow into the bag at one go After you finish emptying your lungs once, immediately twist the bag around the open end to prevent any air from escaping
    • Place the open end of the bag around your mouth in such a way that air won't escape when you blow.

    • Now, take a deep breath and blow into the bag at one go

    • After you finish emptying your lungs once, immediately twist the bag around the open end to prevent any air from escaping

    • Keep the end closed and squeeze, like a toothpaste tube, such that all the air in the bag is compacted to one end of the bag and it now looks like a "thunderstick"

  3. Get a 1-litre plastic water bottle, as cylindrical in shape as possible, and whose girth is similar to that of the inflated plastic bag Measure the "length" of the inflated portion of the plastic bag against the length of the bottle, i.e. how many bottles long is the bag? Each length of the bottle corresponds to ~1 litre, and so this measurement will give you a good estimate of the volume of air you were able to exhale from your lungs in a single breath
    • Get a 1-litre plastic water bottle, as cylindrical in shape as possible, and whose girth is similar to that of the inflated plastic bag

    • Measure the "length" of the inflated portion of the plastic bag against the length of the bottle, i.e. how many bottles long is the bag?

    • Each length of the bottle corresponds to ~1 litre, and so this measurement will give you a good estimate of the volume of air you were able to exhale from your lungs in a single breath

  4. Add the number of bottle-lengths that correspond to the inflated length of the plastic bag and you have an estimate of your exhaled air volume
    • Add the number of bottle-lengths that correspond to the inflated length of the plastic bag and you have an estimate of your exhaled air volume

    • For the case illustrated here : 1 L + 1 L + 0.75 L = 2.75 litres, approximately

    • Note that you can probably not get an accuracy of higher than a quarter litre through this form of estimation/measurement

    • Before taking subsequent measurements, always ensure that you squeeze out all the existing air from the plastic bag

    • Letting air escape when you blow into the bag - Hold the bag tightly to your mouth.

    • Failure to secure the "open" end of the bag immediately after blowing into it.

    • Not squeezing the bag before taking measurements.

    • Loose knot at "closed" end.

  5. Fill the observation table.
    • Fill the observation table.

  6. Plastic bag fitted with a mouthpiece. Spirometer. Balloon instead of plastic bag
    • Plastic bag fitted with a mouthpiece.

    • Spirometer.

    • Balloon instead of plastic bag

    • Click on Lung Capacity (Variations) to do the Variations.

Finish Line

Attached Documents

Kailash NR

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