The effects of ventilatory modes to respiratory mechanics in adults undergoing elective operations

Aim: To investigate the effects of pressure controlled, volume control, pressure-controlled volume guaranteed modes used in anesthesia machine to respiratory mechanics and hemodynamic parameters in patients undergoing elective surgery under general anesthesia in the supine position.Materials and Methods: Patients between 18-65 years of age (n=300) undergoing elective surgery under general anesthesia in operating room were randomized into 3 groups. Group I (n = 100) pressure-controlled, Group II (n = 100) volume control, Group III (n = 100) pressure control volume guaranteed ventilation were performed. Routine monitoring was applied. After intravenous induction, intubated patients were confirmed of tube location and connected to the anesthesia machine. Ventilator mode of anesthesia machine was set according to the patient group. Patient?s anesthesia was maintained with inhaled agents. Demographic data of patients; ECG, heart rate, noninvasive blood pressure, SaO2 and ETCO2, FiO2, inhaled /exhaled volume and concentration of anesthetic agent, respiratory rate, compliance, resistance, peak, plateau and mean airway pressures were recorded for 30 minutes.Results: There were no hemodynamic differences in all three modes in patients. Plateau pressures, peak inspiratory pressures and airway pressures, inspired and expired volumes were significantly increased in pressure-controlled mode. There were no significant differences between volume control modes and pressure-controlled volume guaranteed modes. There were no change at resistances and compliances in any modes.Conclusion: There is no effect on haemodynamic parametres during peri-operative period of different ventilatory modes on anesthesia machine for patients undergoing elective surgery in the supine position. Pressure controlled, volume controlled, pressure-controlled volume guaranteed modes stables patient?s respiratory parameters.Key Words: Volume-controlled mode, pressure-controlled mode, pressure-controlled volume guaranteed mode, spirometry, resistance, compliance, peak inspiratory pressure, plateau pressure, tidal volumeCONTACT ADDRESS: memetoglu@yahoo.com.tr