microtonometer

mi·cro·to·nom·e·ter

(mī'krō-tō-nom'ĕ-tĕr),
A small tonometer invented by Krogh, originally intended for use in animals but later adapted to humans, for determining the tensions of oxygen and carbon dioxide in arterial blood; it provides the means of bringing a small bubble of air into gaseous equilibrium with a sample of blood obtained by arterial puncture.
[micro- + G. tonos, tone, + metron, measure]

microtonometer

(mī″krō-tō-nom′ĕt-ĕr) [ micro- + tonometer]
A device formerly used in clinical laboratories to determine oxygen and carbon dioxide concentrations in blood. It is now used only in research laboratories.