The Safety of Hydrogen in Shunt Detection.

N UMEROUS reports confirm the unequivocally superior sensitivity of hydrogen gas as used electrometrically for the detection of both left-to-right and right-to-left circulatory shunts when the aberrant flow is not clearly definable by oxygen studies.'-8 When used according to any one of the several described methods, in addition to superior sensitivity and immediate recognition of a shunt, it offers reduced complexity of procedure and interpretation and much greater economy than other agents and methods. No special equipment is needed beyond a platinum-tipped or coated electrode catheter, a conventional anesthesia mask-bag-valve, and a $6.00 tank of industrial hydrogen with reducing valve. This quantity of gas is sufficient to permit the recording of several thousand diagnostic curves. For the identification of right-to-left shunts, instead of the anesthetic mask-bag-valve, we have utilized hydrogenated ascorbic acid5 and measured its arrival time in the arterial periphery by means of a platinized tip within an artery to which a second electrocardiographic preamplifier is attached. Wider acceptance of the manifold advantages of hydrogen technics, especially when combined with oximetry for the purpose of quantitation, has been delayed by an understandable reluctance to introduce an explosive gas into the diagnostic laboratory. In an ex-