Physiologic mechanisms of hemostasis and fibrinolysis.

This article describes the interrelated processes and homeostatic controlling mechanisms of hemostasis and fibrinolysis. Hemostasis involves platelets, blood vessels, and coagulation proteins. Primary hemostasis is dependent on platelet adhesion, activation, secretion, and aggregation. Secondary hemostasis consists of intrinsic activation, extrinsic activation, and the common final pathway. Fibrinolysis results in clot dissolution and is initiated endogenously as plasminogen is converted to plasmin.

Right ventricular volumetric monitoring.

The goal of invasive hemodynamic monitoring is to evaluate the components of oxygen delivery and consumption. Parameters obtained from the physiologic profile are used to assess and optimize oxygen delivery to meet the tissue needs of the critically ill patient. Oxygen delivery is defined as cardiac output multiplied by the arterial oxygen content. Research has demonstrated that adequate increases in oxygen delivery improve survival. The primary intervention for optimizing oxygen delivery is appropriate fluid resuscitation. Classic endpoints of adequate fluid resuscitation have been pressure-based parameters, which possess many inherent assumptions. Current clinical issues are directed toward assessment of the patient's status in relation to the oxygen supply-and-demand balance. Identification of therapeutic interventions to achieve the goal of increasing oxygen delivery are paramount. Evaluation of the role of the right ventricle (RV) in biventricular performance and incorporation of volumetric measurements to assess the critically ill patient are presented.