To evaluate the impact of an ascending positive end-expiratory pressure titration strategy on respiratory mechanics and mechanical power in patients without lung injury. An incremental positive end-expiratory pressure titration was performed in 4cmH2O steps, starting from zero end-expiratory pressure and progressing to 16cmH2O. Differences (Δ) in respiratory system static compliance, plateau pressure, driving pressure, and mechanical power were assessed during lung-protective ventilation. Mechanical power formulas proposed by Gattinoni et al. and Costa et al. were used. Analyses were also performed on the static elastic components, dynamic elastic components, total elastic power, and resistive components. Increasing positive end-expiratory pressure levels were associated with a progressive rise in mechanical power, plateau pressure, total and static elastic power, and a decline in compliance. Mechanical power showed strong positive correlations with: ΔPplat (p < 0.001); Δelastic dynamic power (p < 0.001); Δdriving pressure (p < 0.001); and Δtotal elastic power (p < 0.001). Δmechanical power correlated strongly with Δresistive power (p < 0.001), but not with other mechanical power components or mechanics. Progressive positive end-expiratory pressure increase in patients without lung disease significantly raises total mechanical power and its elastic components, particularly static elastic power. These changes may occur silently and without significant alterations in driving pressure or compliance.

Introducción. El aprendizaje basado en problemas virtual (ABPV) ha sido usado en la formación de profesionales de la salud, pero la evidencia sobre el desempeño y la satisfacción estudiantil luego de su implementación es escasa. Objetivos. Evaluar el desempeño de estudiantes de fisioterapia chilenos en la asignatura fisiopatología luego de implementar el APBV y determinar su nivel de satisfacción con esta metodología. Materiales y métodos. Estudio observacional retrospectivo analítico realizado en 106 estudiantes de segundo año de fisioterapia de una universidad de Santiago (Chile) inscritos en la asignatura fisiopatología durante el segundo semestre de 2021. Los estudiantes fueron divididos en 30 grupos de 2 a 6 integrantes y la intervención consistió en la resolución de 2 problemas clínicos (ABPV1 y ABPV2) con un tiempo de trabajo de 5 semanas para cada ABPV (4 semanas de trabajo grupal y 1 semana de evaluación). Las diferencias en los puntajes obtenidos y en el porcentaje de aprobación en la presentación oral (evaluación grupal), la prueba individual escrita, la rúbrica de autoevaluación y la rúbrica de coevaluación entre ABPV1 y ABPV2 fueron evaluadas usando la prueba de Wilcoxon de muestras pareadas y la prueba de Chi cuadrado, respectivamente. Resultados. Los participantes tenían edades entre 19 y 23 años y 50.95% eran mujeres. Respecto al desempeño en la prueba escrita individual, se encontró que en el ABPV1 la mediana de la puntuación fue 13 puntos (p25-p75: 11-14) y 32.08% aprobaron, mientras que en el ABPV2 la mediana de la puntuación fue 9 puntos (p25-p75: 7-12) y 15.09% aprobaron. En la evaluación grupal (30 grupos), la mediana de puntaje fue 62.5 puntos (p25-p75: 59-67) en el ABPV1 y 62.5 puntos (p25-p75: 60-67) en el ABPV2; la tasa de aprobación en el ABPV1 fue 96.67% y en el ABV1, 100%. Respecto a la satisfacción de los estudiantes con el uso de esta metodología en la asignatura, la mayoría expresaron estar “de acuerdo” (24.53-39.62%) y “muy de acuerdo” (35.85-55.56) en los ítems evaluados. Conclusiones. Los estudiantes lograron los objetivos de aprendizaje de la asignatura fisiopatología, por lo que es posible concluir que su desempeño fue adecuado luego de implementar el ABPV, destacando que el desempeño grupal fue superior al desempeño individual. Además, el nivel de satisfacción estudiantil con el uso de esta metodología fue alto.

Background/Objectives: Positive end-expiratory pressure (PEEP) increases end-expiratory lung volume through the addition of PEEP-induced lung volume (PEEPVol), potentially affecting respiratory mechanics and energy load. However, its physiological impact in patients without lung injury remains poorly characterized. We hypothesized that PEEPVol would be closely associated with respiratory system loading beyond conventional respiratory mechanics variables. Methods: We conducted a secondary analysis of a prospective physiological study including 16 deeply sedated, mechanically ventilated adults without lung disease. A standardized incremental PEEP titration (0–16 cmH₂O, steps of 4 cmH₂O) was performed under volume-controlled ventilation. At each step, respiratory mechanics were assessed, including static compliance (Cstat), driving pressure, plateau pressure, and mechanical power. PEEPVol was estimated as PEEP × Cstat, and strain indices were derived relative to predicted functional residual capacity. Linear mixed-effects models evaluated changes across PEEP levels, and associations were initially explored using Spearman correlation and linear regression. To account for repeated measurements within subjects, confirmatory linear mixed-effects regression models were subsequently performed using patients as a random intercept. Results: Incremental PEEP significantly increased PEEPVol, plateau pressure, mechanical power, and both static and global strain (all p < 0.001), while changes in compliance and driving pressure were minimal and not clinically meaningful. PEEPVol showed moderate-to-strong correlations with plateau pressure (ρ = 0.68) and mechanical power (ρ = 0.76) and explained 43% and 56% of their variance, respectively (all p < 0.001);these associations remained significant in additional linear mixed-effects regression analyses accounting for within-subject correlation. PEEPVol also correlated strongly with static strain (ρ = 0.93) and global strain (ρ = 0.83); however, because static strain is calculated as PEEPVol/FRCt, this association is mathematically expected rather than an independent physiological finding and is reported here only for completeness. Notably, 11.1% of measurements exceeded Pplat > 30 cmH₂O and 61.9% exceeded MP ≥ 17 J/min, even at moderate PEEP levels. Conclusions: In patients without lung injury, PEEP-induced increases in lung volume are strongly associated with higher mechanical load and strain, despite minimal changes in compliance or driving pressure. PEEPVol may represent a promising physiological surrogate of static lung deformation and energy transfer, whose potential to improve bedside detection of occult overdistension warrants validation against direct imaging or physiological measurements in larger prospective studies.