Introduction:
The effect of modifying the end inspiratory pause (EIP) on the variations in the physiological dead space (VDphys) in patients undergoing robotic surgery ventilated under a tailored open lung approach has not been addressed before.

Material and methods:
This prospective-paired study was carried out in a tertiary hospital. Following an alveolar recruitment manoeuvre (ARM) and the application of a tailored open-lung positive end-expiratory pressure (PEEPOL), participants consecutively received three EIP levels (30%, 40%, and 10%). The sequence was repeated after pneumoperitoneum and the Trendelenburg position and following a second ARM for patients with suspected lung collapse based on an Air test.

Results:
Eighteen adult subjects were included. The use of an EIP of 10% was asso­ciated with a higher VDphys, both before pneumoperitoneum: 210 mL (IQR 200–237) vs. 197 mL (IQR 173–217) and 196.8 (IQR 185–218) with EIP 30% and 40%, respectively (P < 0.001 and P = 0.006) and after pneumoperitoneum: 212 mL (IQR 198–228) vs. 202 mL (IQR 181–213), P = 0.001. The application of ARMs and PEEPOL led to a significant reduction in driving pressure [5 cmH₂O (IQR 5–6) vs. 7 cmH₂O (IQR 6–10), P < 0.001], despite concurrent increases in PEEP [12 cmH₂O (IQR 10–13) vs. 5 cmH₂O, P < 0.001] and plateau pressure [17 cmH₂O (IQR 16–19) vs. 12 cmH₂O (IQR 12–15)].

Conclusions:
The use of an EIP of 30–40% compared to 10% in patients undergoing robotic surgery optimises lung mechanics and minimises ventilation inefficiencies both before and during the establishment of pneumoperitoneum and Trendelenburg positioning.