Hypoxic hepatitis caused by acute exacerbation of chronic respiratory failure: a case-controlled, hemodynamic study...

Out of a prospective series of 142 consecutive episodes of hypoxic (ischemic) hepatitis (HH), we identified 17 episodes associated with an acute exacerbation of chronic respiratory failure (CRF) without left cardiac failure. In the aim to evaluate the role of arterial hypoxemia in the pathogenesis of HH associated with respiratory failure, these 17 episodes of HH (study group) were hemodynamically compared with a control group of 17 episodes of HH associated with congestive heart failure (CHF) (control group 1) and a group of 16 episodes of acute respiratory failure (ARF) not complicated by HH (control group 2). Arterial hypoxemia was significantly more severe in the study group (arterial blood tension in O2 [PaO2], 34 mm Hg) than in control group 1 (PaO2, 70 mm Hg; P <.0001) and control group 2 (PaO2, 45.5 mm Hg; P =.002). The role of arterial hypoxemia, however, appeared weakened by comparable degrees of systemic hypotension and liver passive congestion in episodes of HH associated with CRF and episodes of HH associated with CHF. Finally, the causative role of arterial hypoxemia emerged from hemodynamic measurements of cardiac index (CI), systemic vascular resistances (SVR), and oxygen transport: systemic hypotension in HH associated with CHF (control group 1) was the result of a fall in CI (median, 2. 33 L/min. m2; range, 1.21-3.14 L/min. m2) associated with high SVR (median, 2,492 dyn. s/cm5. m2; range, 1,382-4,053 dyn. s/cm5. m2), whereas in HH associated with respiratory failure (study group), systemic hypotension was the result of a fall in SVR (median, 1,053 dyn. s/cm5. m2; range, 646-3,148 dyn. s/cm5. m2), resulting in high CI (median, 4.23 L/min. m2; range, 1.9-5.32 L/min. m2) (P =.0087 and. 0038 for cardiac index and SVR, respectively). Moreover, measurements of oxygen transport in patients with HH associated with respiratory failure showed low values of O2 delivery (DO2) (median, 376 mL/min. m2; range, 253-427 mL/min. m2) as a result of extreme arterial hypoxemia despite high CI. In conclusion, these hemodynamic results and additional measurements of hepatic blood flow (HBF) by the method of galactose clearance at a low concentration suggest that in the setting of HH associated with respiratory failure, the liver is not "ischemic," despite hypotension, but rather "hypoxic" as a result of the combination of severe arterial hypoxemia and elevated central venous pressure (CVP).