is kept up on the pad


The question concerns the Beryl's reply here::)
You may have been giving blood, for example. The nurse ought to cushion the removal of the needle from the vein. Pressure is then kept up on the pad to prevent the formation of a nasty bruise.
Could you tell me what 'on' means in 'is kept up on the pad' ? Is that a preposition that could be replaced by 'by' ? (Pressure is then kept up by the pad...)

  • theartichoke

    Senior Member
    English - Canada
    The idea is that you use your hand to press down on the pad against your arm. So the pressure from your hand is on the pad; pressure cannot be exerted by​ the pad itself.
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