What causes oxygen debt

Oxygen extraction and delivery in the elderly during major surgery

detailed description

Background Intra- and postoperative fluid therapy aims to achieve or maintain predetermined levels of oxygen delivery / blood flow thresholds that can be achieved using fluids with or without inotropes. The thresholds used for oxygen delivery were proposed over 40 years ago, in significantly younger patients compared to current patients. Update of the characteristics of perioperative oxygen delivery and consumption are appropriate clinical settings in today's world. Primary result: relative changes in oxygen consumption by anesthesia Secondary results: relative changes in oxygen consumption and supply during surgery and postoperatively, oxygen extraction ratio (measured and estimated), potential markers for the frequency of oxygen debt from post-operative complications in the hospital, mortality (30 days) Population: Men and women ≥ 65 years of age who undergo major / complex surgical interventions intraoperatively. Cardiovascular monitoring is justified by clinical decision. Intervention: no study-related intervention, general anesthesia and surgery according to clinical routine Glare: no glare Study size: Pilot study 1: Feasibility assessment of the study protocol for intraoperative measurements (n = max 10) Pilot study 2: Feasibility assessment of the study protocol for postoperative measurements (n = max 10) Main study: 60 Subjects (20 + ´40) Planned analysis of oxygen consumption after 20 monitored subjects Duration of study: Duration of hemodynamic monitoring 24-36 hours Duration of observation of clinical results: 7-10 days, mortality 30 days after the operation. Examination Events: Monitoring of Oxygen Consumption and Delivery Monitoring of Post-Operative Clinical Results Monitoring of Markers for Tissue Injury Assessments, Procedure, and Timing for Examination Events: Subjects are identified using the surgical planning list and screened for suitability. The study information will be given orally at the first hospital visit. Topics that give written informed consent will be included in the study. Measurements: Oxygen consumption by indirect calorimetry using a face mask (when awake) and via expiration extension tube of the anesthesia machine (state of consciousness) Monitoring of cardiac output using blood samples from the arterial line (LiDCO): arterial and venous blood gas samples, troponin-T urine samples: N-gal clinical results : Data collection from medical records on postoperative complications with the POMS (postoperative morbidity survey) screening survey on days 3.7 and 10. Postoperative mortality on day 30.