The overall objective of this study is to utilize heart rate variability and respiratory rate variability in patients with sepsis to predict clinical deterioration and death.

Our specific objectives are:

1. To study the ability of a change in composite variability (∆CVI) assessment to act as a prognostic aid in predicting disease progression in sepsis.
2. To study the effect that standard resuscitation interventions will have on the direction and magnitude of ∆CVI in patients with sepsis.

B. Hypotheses H1: In the initial resuscitation of sepsis, a low or declining multi-parameter composite variability index (CVI) over 4 hours will predict a significant increase in the combined outcome of overt shock, organ dysfunction, and mortality.

H2: In the initial resuscitation of sepsis, low volume fluid resuscitation (<20 cc/kg) over 4 hours will be associated with a low or declining CVI.

Inclusion Criteria:

• 1. Antibiotics ordered or administered (as surrogate for suspected or confirmed infection as primary reason for hospital admission as determined by the primary team) 2. Serum lactate ≥ 2.0 mmol/L or transient hypotension (any systolic blood pressure < 100 mmHg).

  3. Identification within 12 hours of a qualifying lactate measurement or hypotension episode 4. Hospital admission planned for suspected infection as primary reasons for admission (per emergency medicine team).

Exclusion Criteria:

• 1. Age < 18 years 2. Pregnancy 3. Non-sinus cardiac rhythm (atrial fibrillation, active pacemaker, SVT) 4. Evidence of Overt Shock upon enrollment:

  • Hypotension: SBP < 90 mmHg for ≥ 60 minutes
  • Any vasopressor or inotrope use (e.g. norepinephrine, dopamine, vasopressin, dobutamine) 5. Acute respiratory support (BiPAP or mechanical ventilation) before enrollment 6. Inability to obtain written informed consent from patient or legally authorized representative 7. Inability to wear Zephyr Bioharness device

Patients admitted through the ED for suspected infection as primary reason for admission.