The Relationship Between BCM, Arterial Stiffness and Hemodynamic Instability During Induction of General Anesthesia

Arterial hypotension during induction of general anesthesia is a risk factor for developing postoperative cardiovascular complications. After induction of general anesthesia patients have a high risk of developing arterial hypotension due to anesthetic drugs who can depress cardiac contractility and determine vasodilatation. Previous studies have shown that even short periods of hypotension with a mean arterial pressure of less than 55 mmHg during surgery is associated with an increased incidence of cardiac injury and acute kidney injury in the postoperative period. The volemic status of the patients in the preoperative period is very difficult to quantify and can vary due to comorbidities of the patient, chronic treatment, preoperative fasting. Bioimpedance is recognized by over 30 years as a simple and non invasive technique to determine the volemic status especially in the hemodialysed patients. A new device BCM- Body Composition Monitoring (Fresenius Medical Care) offers a simple method to determine extracellular water and total body water. These volumes are determined by measuring impedance at 50 different frequencies thru electrodes placed at the ankle and wrist. BCM can also determine lean tissue mass and adipose tissue mass. Increasing arterial stiffness is the main characteristic of arterial aging; this increase determines the increase of the afterload, left ventricular hypertrophy, the decrease of coronary and tissue perfusion. Arterial applanation tonometry is a non-invasive technique that has been shown to reliably provide indices of arterial stiffness. In this study investigators wish to determine if there is a correlation between the hidric status determined by BCM, carotid-femural pulse wave velocity determined with SphygmoCor system and the development of hypotension during induction of general anesthesia. The measurements will be obtained before induction of general anesthesia in the pre-surgical area. During induction of general anesthesia with