Adult respiratory distress syndrome. Strategies to provide support and enhance oxygen delivery.

Respiratory failure itself is rarely the cause of death in patients with adult respiratory distress syndrome (ARDS). The multiple-organ failure that often accompanies the syndrome or the underlying disease or trauma that leads to ARDS is more frequently the cause. Thus, care of these patients consists of providing life-sustaining support until they respond to therapy. The authors explain what happens in respiratory failure and how gas exchange can be enhanced in these critically ill patients.     

Plasma alkaline phosphodiesterase I in intrahepatic cholestasis induced by alpha-naphthylisothiocyanate in rats

1. Administration of alpha-naphthylisothiocyanate (ANIT) to rats produced dose-dependent increases in plasma bile acid and bilirubin concentrations. Similar increases in plasma bile acid and bilirubin concentrations were evident in bile duct ligated rats, indicating that the severity of cholestasis is almost identical in both models. 2. Plasma alkaline phosphodiesterase I was increased by only 50-80% while alkaline phosphatase was increased more than threefold after ANIT administration. This is in contrast to an earlier study [S. R. Simpson, K. Rahman & D. Billington (1984) Clinical Science 67, 647-652] where, after bile duct ligation, serum alkaline phosphodiesterase I was elevated sixfold before any increase in alkaline phosphatase activity became apparent. Thus, plasma alkaline phosphodiesterase I does not offer as sensitive a marker of intrahepatic cholestasis (induced by ANIT) as it does of extrahepatic cholestasis (induced by bile duct ligation). 3. Hepatic alkaline phosphodiesterase I was unaffected by ANIT pretreatment while hepatic alkaline phosphatase was increased up to seven times. It is suggested that raised plasma alkaline phosphodiesterase I is due to regurgitation of the biliary enzyme rather than overspill of the enzyme from liver into blood. 4. Gel filtration showed that 24 h and 96 h after ANIT administration, rat serum contained a high molecular weight form of alkaline phosphodiesterase I, suggesting a different isoenzyme profile.