Table 1.

Physiological parameters used to individualize positive end-expiratory pressure.

Parameter Evaluated	Surgical Setting	How to Individualize PEEP	Range of PEEP Studied	Monitoring Tool	Results
∆P [8,34,35,39,40]	Open abdominal surgery [8,34,39,40] Laparoscopy [34,38] Thoracic surgery [34,35]	The lowest PEEP associated with the lowest ∆P [35,39] The highest PEEP associated with the lowest ∆P [38,40]	N/A	None	∆P < 13 cmH2O could reduce PPCs Targeting low ∆P results in low ∆PL
EFL [67]	Open abdominal surgery	PEEP value able to reverse EFL	N/A	None	Lower PPCs in patients with reversed EFL
Pulmonary shunt [91]	Open abdominal surgery Laparoscopy	PEEP associated with the lowest shunt	0 to 10 cmH2O	Beacon system	Better oxygenation
Intra-abdominal pressure [94]	Laparoscopy	PEEP = IAP + 2 cmH2O	10 to 17 cmH2O	IAP measurement	Lower ∆PL
RVDI [95]	Laparoscopy	PEEP associated with the lowest RVDI	8 to 20 cmH2O (IQR)	EIT	Better oxygenation, higher EELV
FRC [98]	Laparoscopy	PEEP able to maintain stable FRC	0 to 20 cmH2O	EIT	Normal FRC, low shunt
Lung collapse and hyperdistension [3]	Laparoscopy	Best compromise between collapse and hyperdistension	6 to 16 cmH2O	EIT	Lower postoperative atelectasis, lower intraoperative ∆P
Airway closure [113]	Laparoscopy, obese patients	PEEP value able to reach AOP	5 to 10 cmH2O	None	High rate of airway closure with PEEP range studied
PL [118]	Laparoscopy, obese patients	PEEP value able to reach PL = 0 cmH2O	10 to 25 cmH2O	Esophageal catheter	Positive PL
∆PL [54]	Laparoscopy, obese patients	PEEP associated with lowest ∆PL	0 to 37 cmH2O	Esophageal catheter	Lower ∆PL

PEEP: positive end-expiratory pressure; ∆P: driving pressure; EFL: expiratory flow limitation; RVDI: regional ventilation delay index; FRC: functional residual capacity; P_L: transpulmonary pressure; ∆P_L: transpulmonary driving pressure.