Abstract

Background: Data on the physiological impact of tracheal intubation and positive end-expiratory pressure (PEEP) on respiratory mechanics in anesthetized children are scarce. We aimed to evaluate the mechanical effects of intubation and PEEP in children without lung pathology under general anesthesia. Methods: Prospective physiologic experimental crossover study, in children under 15 years scheduled for elective surgery. After anesthesia induction and neuromuscular blockade, volume-controlled ventilation was initiated. Respiratory mechanics were assessed before (mask ventilation) and after tracheal intubation, at PEEP 0 and 5 cmH(2)O. Measured variables included peak inspiratory (PIP), plateau (P-PLAT), and total expiratory pressures (tPEEP). Calculated parameters were compliance (Crs), driving pressure (Delta P), and mechanical power (MP). A mixed linear regression model was used. Results: 60 patients were included. Median age 58.0 (18.0-84.0) months. Intubation increased PIP-P-PLAT + 23.9% (p < 0.001), Raw +16.4% (p = 0.011), and Delta P + 20.4% (p < 0.001); and decreased Crs -14% (p = 0.001). PEEP during mask ventilation reduced Delta P 29.1% (p < 0.001) and increased Crs 46.7% (p < 0.001). Combined intubation and PEEP reduced Delta P (-7.9%, p = 0.002) and increased Crs (+19.6%, p < 0.001). PEEP raised MP both during mask ventilation (+50%) and after intubation (+83.3%, both p < 0.001). Children under 2 years showed higher Raw than older children across all conditions (p < 0.001), but similar behavior in Delta P and Crs. Conclusion: PEEP and intubation induce changes in respiratory mechanics. While tracheal intubation increases PIP and Delta P, and decreases Crs, the addition of PEEP partially mitigates these effects on airway pressures, but not on MP. These results suggest a deterioration of both the resistive and elastic components during MV.