Volume Overload: Prevalence, Risk Factors, and Functional Outcome in Survivors of Septic Shock

Abstract

Rationale: Survivors of septic shock have impaired functional status. Volume overload is associated with poor outcomes in patients with septic shock, but the impact of volume overload on functional outcome and discharge destination of survivors is unknown.

Objectives: This study describes patterns of fluid management both during and after septic shock. We examined factors associated with volume overload upon intensive care unit (ICU) discharge. We then examined associations between volume overload upon ICU discharge, mobility limitation, and discharge to a healthcare facility in septic shock survivors, with the hypothesis that volume overload is associated with increased odds of these outcomes.

Methods: We retrospectively reviewed the medical records of 247 patients admitted with septic shock to an academic county hospital between June 2009 and April 2012 who survived to ICU discharge. We defined volume overload as a fluid balance expected to increase the subject's admission weight by 10%. Statistical methods included unadjusted analyses and multivariable logistic regression.

Measurements and main results: Eighty-six percent of patients had a positive fluid balance, and 35% had volume overload upon ICU discharge. Factors associated with volume overload in unadjusted analyses included more severe illness, cirrhosis, blood transfusion during shock, and higher volumes of fluid administration both during and after shock. Blood transfusion during shock was independently associated with increased odds of volume overload (odds ratio [OR], 2.65; 95% confidence interval [CI], 1.33-5.27; P = 0.01) after adjusting for preexisting conditions and severity of illness. Only 42% of patients received at least one dose of a diuretic during their hospitalization. Volume overload upon ICU discharge was independently associated with inability to ambulate upon hospital discharge (OR, 2.29; 95% CI, 1.24-4.25; P = 0.01) and, in patients admitted from home, upon discharge to a healthcare facility (OR, 2.34; 95% CI, 1.1-4.98; P = 0.03).

Conclusions: Volume overload is independently associated with impaired mobility and discharge to a healthcare facility in survivors of septic shock. Prevention and treatment of volume overload in patients with septic shock warrants further investigation.

Keywords: fluid therapy; mobility limitation; outcomes; septic shock; water–electrolyte imbalance.

Figure 1.

Patient selection and outcomes. ¹In the emergency department (ED), patients met at least two of four criteria for systemic inflammatory response syndrome (body temperature >38°C or <36°C, heart rate >90 beats/min, respiratory rate >20 breaths/min or arterial carbon dioxide tension <32 mm Hg, and white blood cell count >12,000/mm³ or <4,000/mm³ or >10% bands) and had suspected infection. After 20 ml/kg crystalloid resuscitation, patients were included if they had systolic blood pressure less than 90 mm Hg, mean arterial pressure less than 60 mm Hg, or lactate greater than 4 mmol/L. ²ICU = intensive care unit.

Figure 2.

Fluids administered during shock and after shock resolution. Shock resolution was defined as the end of 12 hours in the intensive care unit without vasopressors and without more than one mean arterial pressure reading less than 60 mm Hg. Volumes presented are the median for each fluid category. “Other” fluid consists of albumin, blood, total parenteral nutrition, enteral nutrition, free water, and oral fluids. Crystalloid includes dextrose 10% in water, dextrose 5% in lactated Ringer solution, dextrose 5% in water, dextrose 5% in water with 0.45% NaCl, dextrose 5% with 0.45% NaCl-KCl 20 mEq/L, dextrose 5% with 0.45% NaCl-KCl 40 mEq/L, dextrose 5% with 0.9% NaCl, lactated Ringer solution, and sodium chloride 0.9%. Maintenance crystalloid was composed of any of these fluids given at a rate less than 250 milliliters per hour, and bolus crystalloid was any of these fluids given at a rate of 250 milliliters or more per hour.