Meperidine:PrThr:Pt:Ser/Plas:Ord
meperidine:prthr:pt:ser/plas:ord
Meperidine:Presence or Threshold:To identify measures at a point in time:Serum/Plasma:Ordinal
meperidine:presence or threshold:to identify measures at a point in time:serum/plasma:ordinal