Critically ill patients require intravenous administration of fluids and drugs. This can be achieved via peripheral or central catheters. Each device is associated with both mechanical and infectious complications. Complications associated with central lines are judged to be more severe. Some patients actually require the insertion of a central line due to the venous toxicity of the drugs or to the necessity of making sure that the infusion is regularly administered (example: high dose catecholamine infusion). Some physicians believe that most Intensive Care Unit (ICU) patients should have a central venous line inserted, whereas others feel that some patients may receive active drugs via a peripheral line in selected instances. No study prospectively compared the feasibility, merits and complications of the two possibilities (i.e., central or peripheral venous line). This study includes patients that can receive either a central or a peripheral line (see inclusion criteria): mainly patients receiving large amounts of fluid, moderate doses of catecholamines or of drugs that may cause venous injury. Patients are randomized to receive either a peripheral or a central venous catheter. Endpoints are the rate of mechanical complications (difficulty in inserting the line, need for repeat insertion attempts, occurrence of arterial puncture, occurrence of pneumothorax) and of infectious complications (local catheter infection or catheter-related bloodstream infection).