Gerardo Tusman1, Emiliano Gogniat2, Matías Madorno3, Pablo Otero4, José Dianti2, Ignacio Fernandez Ceballos2, Martín Ceballos4, Natalí Verdier4, Stephan H Böhm5, Pablo O Rodriguez6, Eduardo San Roman2. 1. Department of Anesthesiology, Hospital Privado de Comunidad, Mar del Plata, Argentina. gtusman@hotmail.com. 2. Department of Intensive Care Medicine, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina. 3. Instituto Tecnológico Buenos Aires (ITBA), Buenos Aires, Argentina. 4. Anesthesia Department, Veterinary School, Universidad de Buenos Aires, Buenos Aires, Argentina. 5. Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, Rostock, Germany. 6. Pulmonary and Critical Care Medicine, Instituto universitario CEMIC (Centro de Educación Médica e Investigaciones Clínicas), Buenos Aires, Argentina.
Abstract
BACKGROUND: The difference between Bohr and Enghoff dead space are not well described in ARDS patients. We aimed to analyze the effect of PEEP on the Bohr and Enghoff dead spaces in a model of ARDS. METHODS: 10 pigs submitted to randomized PEEP steps of 0, 5, 10, 15, 20, 25 and 30 cm H2O were evaluated with the use of lung ultrasound images, alveolar-arterial oxygen difference (P(A-a)O2 ), transpulmonary mechanics, and volumetric capnography at each PEEP step. RESULTS: At PEEP ≥ 15 cm H2O, atelectasis and P(A-a)O2 progressively decreased while end-inspiratory transpulmonary pressure (PL), end-expiratory PL, and driving PL increased (all P < .001). Bohr dead space (VDBohr /VT), airway dead space (VDaw /VT), and alveolar dead space (VDalv /VTalv ) reached their highest values at PEEP 30 cm H2O (0.69 ± 0.10, 0.53 ± 0.13 and 0.35 ± 0.06, respectively). At PEEP <15 cm H2O, the increases in atelectasis and P(A-a)O2 were associated with negative end-expiratory PL and highest driving PL. VDBohr /VT and VDaw /VT showed the lowest values at PEEP 0 cm H2O (0.51 ± 0.08 and 0.32 ± 0.08, respectively), whereas VDalv /VTalv increased to 0.27 ± 0.05. Enghoff dead space and its derived VDalv /VTalv showed high values at low PEEPs (0.86 ± 0.02 and 0.79 ± 0.04, respectively) and at high PEEPs (0.84 ± 0.04 and 0.65 ± 0.12), with the lowest values at 15 cm H2O (0.77 ± 0.05 and 0.61 ± 0.11, respectively; all P < .001). CONCLUSIONS: Bohr dead space was associated with lung stress, whereas Enghoff dead space was partially affected by the shunt effect.
BACKGROUND: The difference between Bohr and Enghoff dead space are not well described in ARDS patients. We aimed to analyze the effect of PEEP on the Bohr and Enghoff dead spaces in a model of ARDS. METHODS: 10 pigs submitted to randomized PEEP steps of 0, 5, 10, 15, 20, 25 and 30 cm H2O were evaluated with the use of lung ultrasound images, alveolar-arterial oxygen difference (P(A-a)O2 ), transpulmonary mechanics, and volumetric capnography at each PEEP step. RESULTS: At PEEP ≥ 15 cm H2O, atelectasis and P(A-a)O2 progressively decreased while end-inspiratory transpulmonary pressure (PL), end-expiratory PL, and driving PL increased (all P < .001). Bohr dead space (VDBohr /VT), airway dead space (VDaw /VT), and alveolar dead space (VDalv /VTalv ) reached their highest values at PEEP 30 cm H2O (0.69 ± 0.10, 0.53 ± 0.13 and 0.35 ± 0.06, respectively). At PEEP <15 cm H2O, the increases in atelectasis and P(A-a)O2 were associated with negative end-expiratory PL and highest driving PL. VDBohr /VT and VDaw /VT showed the lowest values at PEEP 0 cm H2O (0.51 ± 0.08 and 0.32 ± 0.08, respectively), whereas VDalv /VTalv increased to 0.27 ± 0.05. Enghoff dead space and its derived VDalv /VTalv showed high values at low PEEPs (0.86 ± 0.02 and 0.79 ± 0.04, respectively) and at high PEEPs (0.84 ± 0.04 and 0.65 ± 0.12), with the lowest values at 15 cm H2O (0.77 ± 0.05 and 0.61 ± 0.11, respectively; all P < .001). CONCLUSIONS: Bohr dead space was associated with lung stress, whereas Enghoff dead space was partially affected by the shunt effect.
Authors: Fernando Suárez-Sipmann; Jesús Villar; Carlos Ferrando; Juan A Sánchez-Giralt; Gerardo Tusman Journal: Front Physiol Date: 2021-12-21 Impact factor: 4.566