Critical care medicine is a dynamic and exciting arena where complex pathophysiologic states require extensive knowledge and up-to-date clinical information. An extensive kno- edge of basic pathophysiology, as well as awareness of the appropriate diagnostic tests and treatments that are used to optimize care in the critically ill is essential. Since our frst edition 7 years ago, new information crucial to the care and understanding of the critically ill patient has rapidly accumulated. Because this knowledge base crosses many different disciplines, a comprehensive multidisciplinary approach presenting the information is essential, similar to the multidisciplinary approach that is used to care for the critically ill patient. We have strived to provide this content in an easily digestible format that uses a variety of teaching tools to facilitate understanding of the presented concepts and to enhance information retention. To meet the demand to provide comprehensive and diverse educationin order to und- stand the pathogenesis and optimum care of a variety of critical illnesses, we have subst- tially revised the prior topics in the frst edition with updated information. We have also markedly expanded the number of topics covered to include acute lung injury and the acute respiratory distress syndrome, an expanded discussion of the physiology and operation of mechanical ventilation, obstetrical care in the ICU, neurosurgical emergencies, acute co- nary syndromes, cardiac arrhythmias, role of whole body rehabilitation in the ICU, ethical conduct of human research in the ICU, and nursing care of the ICU patient.