Correlation between Carbon Dioxide Production and Mean Arterial Blood Pressure in Fluid Response in Mechanically Ventilated Patients

Abstract
Background: Volume expansion through fluid administra-tion is one of the simplest approaches for initial treatment of hemodynamic instability. In the Intensive Care Unit (ICU) a newly available technique called volumetric capnography (Vcap) allows measurement of carbon dioxide production (VCO2) on a regular basis at the bedside.
Aim of Study: The aim of the study was to evaluate VCO2 as an endpoint predictor for fluid resuscitation in mechanically ventilated patients.
Methods and Material: This prospective cohort study was carried out on 70 patients in Tanta University Hospitals at surgical ICU from August 2017 till August 2018. All patients included in the study were on controlled mechanical ventilation with tidal volume 6-8ml.kg–1 ideal body weight. Wide bore intravenous lines were inserted and patients were completely sedated and monitored by; pulse oximeter, non-invasive blood pressure monitoring, ECG all connected to monitor (infinium medical-OMNI lll-FL33773-USA). Volumetric capnogram, end tidal capnogram, detected by Y-Piece and sample line connected to (GE Healthcare Finland Oy, E-sCOVX-00- Finland). Bispectral Index (BIS) to assess the depth of sedation (should be between 40-60). Intravenous fluids were given after hypotension till MAP >65mmHg.
Results: There was significant increase in MAP and VCO2 and significant decrease in HR after fluid resuscitation and there was no significance difference in BIS, SpO2. There was positive correlation between VCO2 and MAP with sensitivity of VCO2 for fluid responsiveness 92%.
Conclusions: VCO2 and EtCO2 are good monitoring toolswhichare well correlated with hemodynamic changes, thus can be used as an indicator for fluid responsiveness and endpoint prediction ofresuscitation.