Our research objective is to study organization and communication as risks factors in a public health setting. We chose to study central venous catheterization, which is often necessary to treat critically ill patients hospitalized in Intensive Care Units. This procedure can lead to serious and sometimes life-threatening complications, whether mechanical, infectious or thrombotic. However, while there are many medical studies that treat this subject, few include non medical risk factors like the organization of the care, communication inter and intrateams, team experience, etc. Method: A study was conducted in two intensive care units (ICU) belonging to two different university hospitals. The aim of this study was to identify the root causes of incidents related to this medical device. Part of the study is a sociological approach based on the analysis of the way clinical functions are organized and can fail. First, this sociological step generated both a description and a basic framework of daily patient care. This work was characterized by a total immersion in the two intensive care units. The method consisted of on site observations combined with interviews with the various categories of caregivers. This 3 month period was supplemented by a yearlong follow-up study of all incidents of catheter use for these two units. During this part of the study, the complications related to these devices were identified on the basis of mandatory reporting on a specific form. This led to debriefings for all of the staff involved in the care of these particular patients. The objective was to retrospectively describe the chain of events and the critical points having led to this failure. Preliminary Results: We have studied around 350 patients and 600 central venous catheters. Around 10 incidents have been debriefed. The observation of the functioning of these 2 ICU highlights their organizational differences. Those two organizational hierarchies tend to generate different types of complications each with a unique pattern of delays, errors and recovery times. The interest of this study shows that by changing organizational structure one can possibly modify patient risk. Then, in order to reduce risks related to a medical device and enhance patient safety, it is important to lead caregivers to work on their clinical functions, team work and type of communication.