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 H 2 O were evaluated with the use of lung ultrasound images, alveolar-arterial oxygen difference (P (A-a)O 2), transpulmonary mechanics, and volumetric capnography at each PEEP step. RESULTS: At PEEP > 15 cm H 2 O, atelectasis and P (A-a)O 2 progressively decreased while endinspiratory transpulmonary pressure (P L), end-expiratory P L , and driving P L increased (all P < .001). Bohr dead space (V D Bohr /V T), airway dead space (V D aw /V T), and alveolar dead space (V D alv /V T alv) reached their highest values at PEEP 30 cm H 2 O (0.69 ؎ 0.10, 0.53 ؎ 0.13 and 0.35 ؎ 0.06, respectively). At PEEP <15 cm H 2 O, the increases in atelectasis and P (A-a)O 2 were associated with negative end-expiratory P L and highest driving P L. V D Bohr /V T and V D aw /V T showed the lowest values at PEEP 0 cm H 2 O (0.51 ؎ 0.08 and 0.32 ؎ 0.08, respectively), whereas V D alv /V T alv increased to 0.27 ؎ 0.05. Enghoff dead space and its derived V D alv /V T alv 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 H 2 O (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.

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Neurostimulation was a useful technique to determine correct intrathecal needle placement in rabbits but failed to detect the lumbosacral epidural space when the common technique, used in dogs and cats for the lumbosacral epidural approach, was used.

The current COVID-19 pandemic has led the world to an unprecedented global shortage of ventilators, and its sharing has been proposed as an alternative to meet the surge. This study outlines the performance of a preformed novel interface called ’ACRA’, designed to split ventilator outflow into two breathing systems. The ’ACRA’ interface was built using medical use approved components. It consists of four unidirectional valves, two adjustable flow-restrictor valves placed on the inspiratory limbs of each unit, and one adjustable PEEP valve placed on the expiratory limb of the unit that would require a greater PEEP. The interface was interposed between a ventilator and two lung units (phase I), two breathing simulators (phase II) and two live pigs with heterogeneous lung conditions (phase III). The interface and ventilator adjustments tested the ability to regulate individual pressures and the resulting tidal volumes. Data were analyzed using Friedman and Wilcoxon tests test (p < 0.05). Ventilator outflow splitting, independent pressure adjustments and individual tidal volume monitoring were feasible in all phases. In all experimental measurements, dual ventilation allowed for individual and tight adjustments of the pressure, and thus volume delivered to each paired lung unit without affecting the other unit’s ventilation—all the modifications performed on the ventilator equally affected both paired lung units. Although only suggested during a dire crisis, this experiment supports dual ventilation as an alternative worth to be considered.