Marathoners’ Breathing Pattern Protects Against Lung Injury by Mechanical Ventilation: An Ex Vivo Study Using Rabbit Lungs

Abstract

Background Breathing during a marathon is often empirically conducted in a so-called "2:2 breathing rhythm," which is based on a four-phase cycle, consisting of the 1st and 2nd inspiratory and the 1st and 2nd expiratory phases. We developed a prototype ventilator that can perform intermittent positive pressure ventilation, mimicking the breathing cycle of the 2:2 breathing rhythm. This mode of ventilation was named the marathoners' breathing rhythm ventilation (MBV). We hypothesized that MBV may have a lung protective effect. Methods We examined the effects of the MBV on the pulmonary pre-edema model in isolated perfused rabbit lungs. The pulmonary pre-edema state was induced using bloodless perfusate with low colloid osmotic pressure. The 14 isolated rabbit lung preparations were randomly divided into the conventional mechanical ventilation (CMV) group and MBV group, (both had an inspiratory/expiratory ratio of 1/1). In the CMV group, seven rabbit lungs were ventilated using the Harvard Ventilator 683 with a tidal volume (TV) of 8 mL/kg, a respiratory rate (RR) of 30 cycles/min, and a positive end-expiratory pressure (PEEP) of 2 cmH 2 O for 60 min. In the MBV group, seven rabbit lungs were ventilated using the prototype ventilator with a TV of 6 mL/kg, an RR of 30 cycles/min, and a PEEP of 4 cmH 2 O (first step) and 2 cmH 2 O (second step) for 60 min. The time allocation of the MBV for one cycle was 0.3 s for each of the 1st and 2nd inspiratory and expiratory phases with 0.2 s of intermittent resting between each phase. Results Peak airway pressure and lung wet-to-dry ratio after 60 min of ventilation were lower in the MBV group than in the CMV group. Conclusion MBV was considered to have a lungprotective effect compared to CMV.

Technical Advances Targeting Multiday Preservation of Isolated Ex Vivo Lung Perfusion

“…As compared with PPV, the tidal volume will be delivered via 2 equal inspiratory phases, therefore reducing airway pressures and the risk of VILI. 138 The Tottori group tested this type of ventilation in EVLP settings and demonstrated decreased incidence of lung edema. 138…”

“…138 The Tottori group tested this type of ventilation in EVLP settings and demonstrated decreased incidence of lung edema. 138…”

Diagnostic and Therapeutic Implications of Ex Vivo Lung Perfusion in Lung Transplantation: Potential Benefits and Inherent Limitations

“…[126][127][128] In addition to changes in the pressure and position of ventilation, advantages of other optimized ventilatory patterns during EVLP, including personalized positive end-expiratory pressure titration, pressure-directed airway pressure release, and marathoners' breathing patterns, have also been suggested. [129][130][131] Nevertheless, most studies have been based on preclinical models, and more clinical trials are required to validate the above interventions.…”