Acute respiratory distress syndrome (ARDS) alters the dynamics of lung inflation during mechanical ventilation. Repetitive alveolar collapse and expansion (RACE) predisposes the lung to ventilator-induced lung injury (VILI). Two broad approaches are currently used to minimize VILI: (1) low tidal volume (LVT) with low-moderate positive end-expiratory pressure (PEEP); and (2) open lung approach (OLA). The LVT approach attempts to protect already open lung tissue from overdistension, while simultaneously resting collapsed tissue by excluding it from the cycle of mechanical ventilation. By contrast, the OLA attempts to reinflate potentially recruitable lung, usually over a period of seconds to minutes using higher PEEP used to prevent progressive loss of end-expiratory lung volume (EELV) and RACE. However, even with these protective strategies, clinical studies have shown that ARDS-related mortality remains unacceptably high with a scarcity of effective interventions over the last two decades. One of the main limitations these varied interventions demonstrate to benefit is the observed clinical and pathologic heterogeneity in ARDS. We have developed an alternative ventilation strategy known as the Time Controlled Adaptive Ventilation (TCAV) method of applying the Airway Pressure Release Ventilation (APRV) mode, which takes advantage of the heterogeneous time- and pressure-dependent collapse and reopening of lung units. The TCAV method is a closed-loop system where the expiratory duration personalizes VT and EELV. Personalization of TCAV is informed and tuned with changes in respiratory system compliance (CRS) measured by the slope of the expiratory flow curve during passive exhalation. Two potentially beneficial features of TCAV are: (i) the expiratory duration is personalized to a given patient's lung physiology, which promotes alveolar stabilization by halting the progressive collapse of alveoli, thereby minimizing the time for the reopened lung to collapse again in the next expiration, and (ii) an extended inspiratory phase at a fixed inflation pressure after alveolar stabilization gradually reopens a small amount of tissue with each breath. Subsequently, densely collapsed regions are slowly ratcheted open over a period of hours, or even days. Thus, TCAV has the potential to minimize VILI, reducing ARDS-related morbidity and mortality.
Respiratory Distress Syndrome , Ventilator-Induced Lung Injury , Humans , Respiration, Artificial/methods , Lung/pathology , Pulmonary Alveoli/pathology , Respiratory Distress Syndrome/diagnosis , Respiratory Distress Syndrome/therapy , Respiratory Distress Syndrome/pathology , Continuous Positive Airway Pressure/methods , Tidal Volume , Ventilator-Induced Lung Injury/prevention & control , Ventilator-Induced Lung Injury/pathology
Reports of children with a temporal association to severe acute respiratory syndrome coronavirus-2 hospitalized with cardiogenic shock or Kawasaki-like disease began emerging in April 2020. In May 2020, the Centers for Disease Control and Prevention published the criteria for what came to be known as multisystem inflammatory syndrome in children, a postinfectious inflammatory immune response to coronavirus disease 2019 exposure. Hemophagocytic lymphohistiocytosis is a heterogeneous disease state associated with systemic hyperinflammation secondary to immune dysregulation. We describe the utility of perioperative lung ultrasound in an infant with both disease states.
