ObjectiveTo determine if treatment modalities (fluid, inotropes, and blood) would be altered based on preload measurements of right ventricular end-diastolic volume index measured by fast response thermodilution catheter, as compared with pulmonary artery occlusion pressure (PAOP).DesignA prospective clinical trial.SettingAn 11-bed surgical intensive care unit (ICU) at The Queen's Medical Center, an affiliate of the University of Hawaii Surgical Residency program.PatientsSurgical ICU patients who required pulmonary artery catheters, except those patients with arrhythmias or history of tricuspid valve disease.Interventions120 beats/min, urine output of <40 mL/hr, stroke volume of <40 mL/m2with oxygen delivery of <450 mL/min/m2, and lactic acidosis. Volume infusion was considered if PAOP was <18 mm Hg and right ventricular end-diastolic volume index was <140 mL/m218 mm Hg to prevent pulmonary edema. When PAOP and right ventricular end-diastolic volume index gave conflicting information, other clinical parameters were assessed to determine treatment.Measurements and Main ResultsTwenty-seven patients requiring 70 catheters were evaluated for the study. Thirteen patients with 46 pairs of data points completed the study. Fourteen patients were excluded from analysis due to irregular heart rate, poor quality of cardiac output at the time of volume infusion, or lack of major volume manipulation. PAOP and right ventricular end-diastolic volume index measurements agreed in 42 of 46 instances (PAOP of <18 mm Hg, right ventricular end-diastolic volume index of <140 mL/m218 mm Hg, right ventricular end-diastolic volume index was <140 mL/m218 mm Hg with right ventricular end-diastolic volume index of <140 mL/m2. A rigid abdomen accompanied hypotension, tachycardia and low urine output. Thus, a fluid bolus was administered, resulting in improved blood pressure, stroke volume, and heart rate.or=to10 cm H2O, to avoid the effects of high intrapleural pressure on PAOP readings. Cardiac output was measured at end-expiration, and stroke volume index and right ventricular end diastolic volume index were derived.ConclusionsIn this small sample of surgical patients with sepsis, adult respiratory distress syndrome, and hemorrhagic shock (n = 13), the additional information derived from right ventricular end-diastolic volume index did not change treatment in 43 of 46 instances. However, patients with increased intra-abdominal pressures may show misleadingly high PAOP despite low preload. These patients clearly benefitted from the additional information derived from ventricular volume measurements. Additionally, clinicians who are reluctant to take off-PEEP PAOP may also find this catheter useful.(Crit Care Med 1995; 23:681-686)