Low systemic vascular resistance: differential diagnosis and outcome

Objective: To determine the frequency and prognosis of the various causes of low systemic vascular resistance (SVR). Design: Analysis of consecutive patients over a 5-year period; retrospective review. Setting: Medical intensive care unit of a large university hospital. Patients: Fifty-five patients with unexplained hypotension and a SVR less than 800 dynes x s/cm(5). Background: There are minimal data in the medical literature determining the frequency or outcome of patients with a low SVR that is unrelated to sepsis or the sepsis syndrome. We retrospectively reviewed and analyzed all hemodynamic data in a large university hospital over a 5-year period to determine the frequency and prognosis of the various causes of low SVR. Fifty-five patients with unexplained hypotension and a SVR less than 800 dynes x s/cm(5) were identified. Main results: Twenty-two patients (Groups 1 and 2) met the criteria for sepsis syndrome. The mean SVR for this group was 445 +/- 168 dynes x s/cm(5) with an associated mortality of 50%. Group 3 contained 20 patients with possible sepsis. Thirteen patients (Group 4) were nonseptic. The mean SVR of this group was 435 +/- 180 dynes x s/cm(5) with an associated mortality of 46%. Extremely low SVR (below 450 dynes x s/cm(5)) was associated with a significantly higher mortality regardless of the etiology. Conclusions: At least a quarter of patients with hypotension and a low SVR have nonseptic etiologies. The patients with nonseptic etiologies have a similar mortality to septic patients. Clinicians should be aware of the wide spectrum of conditions that induce a low SVR.