When blood flow is arrested during cardiopulmonary bypass (CPB), the tissue suffers progressive alterations. Gastric impedance spectroscopy, a novel tool used to monitor and detect tissue ischemia is compared with hemodynamic variables as CI, MAP, MPAP, CVP, PCWP; and regional perfusion variables as PCO2 gap and gastric intramucosal pH, to find differences according to outcome for patients undergoing elective cardiovascular surgery.
Impedance spectrometry probe and nasogastric tube (ISP/NGT), and a tonometer were placed in the stomach of 56 patients under coronary artery bypass (CABG) and/or valvular surgery with CPB and aortic cross-clamp. Hemodynamic monitoring was performed via pulmonary artery and radial artery catheters, inserted before the operation. Impedance spectra of the gastric wall and hemodynamic variables were recorded perioperatively and for up to 4 hours after surgery. Pre-surgical and post- surgical measurements comparison was made to assess which variable is better associated with mortality using ANOVA.
Eighteen (34.61%) patients developed complications within a 72h period after surgery; seven (13.46%) died. Nine (17.3%) patients developed complications after ICU release. Table 1 shows that impedance spectroscopy variables (R316 and X316) and CI showed significant differences between survivors and non survivors. The other hemodynamic and regional perfusion variables did not differ between groups. Only CI, CO2 gap and pHi showed statistical differences before and after surgery.
Our data suggest that gastric impedance spectra may be a good predictor of outcome after cardiac surgery. Further analysis is ongoing to extract and assess the diagnostic/prognostic value of these measurements.
Gastric impedance spectroscopy may be a useful tool to assess splanchnic perfusion and tissue viability in critical care patients.
Table 1VariableSurvivorsNon SurvivorspPre-surgeryPost-surgeryPre-surgeryPost-surgeryR31674.2±3.575.2±3.596.4±9.379.3±9.30.0024*X316-16.6±1.5-19.4±1.5-26.9±3.9-27.1±3.90.0003*CI2.4±0.13.3±0.12.3±0.32.3±0.30.0270*CO2gap7.0±1.218.2±1.28.6±3.325.2±3.30.0841pHi7.34±0.017.21±0.017.30±0.047.17±0.040.2384MAP75.0±1.380.7±1.373.8±3.375.7±3.30.2181PCWP17.2±0.911.4±0.912.6±2.414.8±2.40.7532CVP10.4±0.610.3±0.69.2±1.613.9±1.60.3031MPAP27.3±1.225.2±1.326.5±3.524.5±3.50.7743
Nohra Beltran Vargas, Grant monies (from industry related sources) This research was supported by a grant from Innovamédica S.A. de C.V. with concurrent support from CONACYT.; Product/procedure/technique that is considered research and is NOT yet approved for any purpose. Innovamedica is sole assignee of the patent related to the technology using in this work. The impedance spectrometer is not commercial yet.