Pulmonary artery catheter (PAC) use has led to major advances in the assessment of hemodynamics. Since its introduction three decades ago, features have been added to the PAC to enhance its hemodynamic monitoring capabilities. In addition, newer technologies have been proposed to replace the PAC. This article discusses three features that enhance the PAC-measures of mixed venous oxyhemoglobin, right ventricular ejection fraction, and continuous cardiac output-and two newer technologies-esophageal Doppler and exhaled carbon dioxide measurements. The article describes current and future applications of hemodynamic monitoring.