Veno‐arterial Shunting of Blood in Chronic Liver Disease

Summary Seventeen out of 43 patients with chronic liver disease had arterial oxygen unsaturation at rest breathing room air. This incidence is higher than has been recognized in the past. The degree and basis of this arterial oxygen unsaturation were studied further in 14 patients, of whom seven had arterial oxygen unsaturation at rest. An alveolar‐capillary diffusion defect played some part in its production in one patient, and the ventilation‐perfusion inequality of chronic airway disease was partly or wholly responsible in five others. After allowance had been made for respiratory factors, there remained at least six, and possibly 10, patients out of 14 in whom an abnormal degree of veno‐arterial shunting of blood could be demonstrated. The dimensions of this shunt ranged up to more than 20% of the cardiac output. On theoretical grounds, it is likely that a significant part of the veno‐arterial shunting is intrapulmonary.