German Clinical Trials Register

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Brief summary in lay language

General anesthesia leads to an uneven distribution of the respiratory gas in the lung, especially during laparoscopic procedures (e.g., robot-assisted laparoscopic prostatectomy). This effect is further exacerbated by the head-down positioning required to perform the surgery. The consequences of the uneven distribution of respiratory gas in the lung are collapse of poorly ventilated lung areas (atelectasis) and overdistension of excessively ventilated lung areas (hyperinflation). The described changes increase the risk of perioperative complications affecting the lung and represent an important factor influencing the complication rate after surgical interventions. A possibility to improve the distribution of respiratory gas in the lung is to ventilate with positive pressure remaining in the lung at the end of expiration (PEEP, positive end-expiratory pressure). The positive pressure in the lung at the end of expiration counteracts the pressures acting on the lung from outside, and the difference is called the "transpulmonary pressure". If the transpulmonary pressure is positive, collapse of the lung areas is prevented. The individually optimal positive end-expiratory pressure (PEEP) for each patient, which guarantees a positive transpulmonary pressure and thus prevents collapse of the lung, cannot be determined without individual measurement. The aim of this study is to evaluate the individualized ventilatory setting adapted to the operative conditions in comparison to the routinely used setting. In particular, the effects of an individual PEEP on the patient's respiratory mechanics influenced by the changing operative conditions will be characterized.

Brief summary in scientific language

General anesthesia with mechanical ventilation leads to inhomogeneities in the lung parenchyma with the development of dorsobasal atelectasis and apical hyperinflation due to the necessary muscle relaxation and intubation. Laparoscopic procedures with pneumoperitoneum and especially robot-assisted laparoskopische prostatectomy with additional Trendelenburg positioning lead to aggravation of the described inhomogeneities by increased intra-abdominal pressure, displacement of the diaphragm cranially and influence of the thoracic wall. The resulting alteration of respiratory mechanics with increased airway pressures, end-expiratory airway collapse, and development of atelectasis increases the risk of perioperative pulmonary complications and ventilator-associated lung injury. Intraoperative lung-protective ventilation with low tidal volumes and adequate positive end-expiratory pressure (PEEP) has been identified as an effective measure to reduce perioperative pulmonary complications. Identification of adequate PEEP under the dynamic operative conditions with pneumoperitoneum and Trendelenburg positioning during robotic-assisted laparoscopic prostatectomy requires a comprehensive evaluation of respiratory mechanics. The aim of the present study is to evaluate the ventilation settings individually adapted to the operative conditions in patients during robot-assisted laparoscopic prostatectomy. In particular, the effects of an individual PEEP on the patient's respiratory mechanics altered by changing surgical measures will be characterized.