Using bioimpedance analysis to assess intensive care unit patients with sepsis in the post-resuscitation period: a prospective multicentre observational study.

PURPOSE: Clinicians lack well-validated, non-invasive, objective tools to guide volume management in the post-resuscitative period. Bioimpedance analysis (BIA) represents a novel method for guiding fluid management. We studied the relationship of BIA vector length (VL), an indicator of volume status, to the need for mechanical ventilation in patients with sepsis. METHODS: This is a multicentre prospective observational study at four Canadian ICUs. We examined adult patients admitted to the ICU within 72 hr of a sepsis diagnosis. Patients underwent daily BIA measurements for 30 days, until discharge from the ICU, or until death. Our primary outcome was the ongoing need for invasive mechanical ventilation, and we examined the association with VL using a generalized estimating equation. Our secondary analyses were targeted to determine an association between VL and other measures of volume status and acute kidney injury (AKI). RESULTS: We enrolled 159 patients from four centres over 27 months. The mean (standard deviation [SD]) age was 64 (15) yr with a mean (SD) APACHE (acute physiology, age, chronic health evaluation) II score of 25 (10); 57% (n = 91) were male. A 50-unit (ohm·m) increase in VL over any time period was associated with a 30% decrease in the probability of requiring invasive mechanical ventilation (P < 0.03). Volume expansion, indicated by a shorter VL, correlated with higher edema scores (r = - 0.31; P < 0.001) and higher net 24-hr fluid balance (r = - 0.27, P < 0.001). Patients with AKI had a shorter overall VL (r = - 0.23; P = 0.003). CONCLUSIONS: An increase in VL over time is associated with a decrease in probability of requiring invasive mechanical ventilation. Vector length correlates with other commonly used volume assessment methods in post-resuscitation patients with sepsis.

Assessment of Postresuscitation Volume Status by Bioimpedance Analysis in Patients with Sepsis in the Intensive Care Unit: A Pilot Observational Study.

Background. Bioimpedance analysis (BIA) is a novel method of assessing a patient's volume status. Objective. We sought to determine the feasibility of using vector length (VL), derived from bioimpedance analysis (BIA), in the assessment of postresuscitation volume status in intensive care unit (ICU) patients with sepsis. Method. This was a prospective observational single-center study. Our primary outcome was feasibility. Secondary clinical outcomes included ventilator status and acute kidney injury. Proof of concept was sought by correlating baseline VL measurements with other known measures of volume status. Results. BIA was feasible to perform in the ICU. We screened 655 patients, identified 78 eligible patients, and approached 64 for consent. We enrolled 60 patients (consent rate of 93.8%) over 12 months. For each 50-unit increase in VL, there was an associated 22% increase in the probability of not requiring invasive mechanical ventilation (IMV) (p = 0.13). Baseline VL correlated with other measures of volume expansion including serum pro-BNP levels, peripheral edema, and central venous pressure (CVP). Conclusion. It is feasible to use BIA to predict postresuscitation volume status and patient-important outcomes in septic ICU patients. Trial Registration. This trial is registered with clinicaltrials.gov NCT01379404 registered on June 7, 2011.