Observational Study to Evaluate Peripheral IntraVenous Analysis (PIVA) in Euvolemic, Hypovolemic, and Hypervolemic Emergency Department Patients

Control Cohort (Presumed Euvolemia) Inclusion Criteria: * Age \> 18 years old * Assessed as "euvolemic" by treating physician Exclusion Criteria: * History of any type of decreased oral intake or volume loss (e.g. diarrhea, vomiting, etc) * History of a fever * History of bleeding * Any acute illness expected to alter volume * Known or suspected pregnancy * Active irregular heart rhythm * In the opinion of the treating physician, no anticipated intravenous fluid administration * History of chronic or end stage renal disease * Liver failure * History of Acute heart failure * Presence of abnormal vital signs (90 \< HR \< 60; 180 \< SBP \< 110, respiratory rate \> 20, pulse ox \< 92% or need for supplemental oxygen, 99.0 \< temperature \< 96). 2 additional group will be included in this euvolemic group * Non-elderly patients (age \< 50 year) without any comorbid illnesses and * Age \>65 * Diabetes on medications * Hypertension on medications * Vascular disease defined by history of peripheral vascular disease, stroke, MI Note: patients that receive \>250 cc of IVF will be excluded from analysis. Infection Cohort (Presumed Hypovolemia) Inclusion Criteria: * Age \> 18 years old * An accessible intravenous catheter is in place * Known or suspected infection as assessed by the clinical team * Intention to admit to the hospital * Anticipated administration of intravenous fluids per clinical team Exclusion Criteria: * Clinical exam consistent with volume overload * Known …