Assessment of indices of preload and volume responsiveness

PURPOSE OF REVIEW: To summarize the relevant peer-reviewed publications over the past year that addressed issues of when to give (or not give) fluid to the critically ill patient. RECENT FINDINGS: Clinical data from several studies underscore the inability of measures of ventricular filling to assess either preload or preload responsiveness. Whereas less invasive monitoring techniques than pulmonary arterial catheterization demonstrate better discrimination with estimates of both preload and preload responsiveness. Measuring dynamic changes in stroke volume, descending aortic flow, and both superior and inferior vena caval diameters during ventilation provides good predictive value in defining preload responsiveness. One study demonstrated that resuscitation protocols keyed to esophageal flow measures improved outcome in postoperative cardiac surgery patients. SUMMARY: Preload is not preload responsiveness. Functional measures of preload responsiveness exist and are superior to traditional measures of filling pressures in driving resuscitation in critically ill patients.