Physiological and Pathophysiological Consequences of Mechanical Ventilation

Abstract

Mechanical ventilation is a life-support system used to ensure blood gas exchange and to assist the respiratory muscles in ventilating the lung during the acute phase of lung disease or following surgery. Positive-pressure mechanical ventilation differs considerably from normal physiologic breathing. This may lead to several negative physiological consequences, both on the lungs and on peripheral organs. First, hemodynamic changes can affect cardiovascular performance, cerebral perfusion pressure (CPP), and drainage of renal veins. Second, the negative effect of mechanical ventilation (compression stress) on the alveolar-capillary membrane and extracellular matrix may cause local and systemic inflammation, promoting lung and peripheral-organ injury. Third, intra-abdominal hypertension may further impair lung and peripheral-organ function during controlled and assisted ventilation. Mechanical ventilation should be optimized and personalized in each patient according to individual clinical needs. Multiple parameters must be adjusted appropriately to minimize ventilator-induced lung injury (VILI), including: inspiratory stress (the respiratory system inspiratory plateau pressure); dynamic strain (the ratio between tidal volume and the end-expiratory lung volume, or inspiratory capacity); static strain (the end-expiratory lung volume determined by positive end-expiratory pressure [PEEP]); driving pressure (the difference between the respiratory system inspiratory plateau pressure and PEEP); and mechanical power (the amount of mechanical energy imparted as a function of respiratory rate). More recently, patient self-inflicted lung injury (P-SILI) has been proposed as a potential mechanism promoting VILI. In the present chapter, we will discuss the physiological and pathophysiological consequences of mechanical ventilation and how to personalize mechanical ventilation parameters.

Effects of different fluid management on lung and kidney during pressure‐controlled and pressure‐support ventilation in experimental acute lung injury

“…In addition, lung edema may increase further if tight junction connections, as occludin, which are constitutive in epithelial and endothelial structural cells, are lost during the stretch movements (Cavanaugh Jr et al, 2001). During assisted spontaneous ventilation such as pressure‐support ventilation (PSV), pleural pressure decreases, leading to tensile stress (Silva et al, 2022), whereas during pressure‐controlled ventilation (PCV), a positive increase in pleural pressure is observed, resulting in compressive stress (Silva & de Abreu, 2018). The difference between tensile and compressive stresses has been studied both in vitro (Bachofen et al, 1987; Tschumperlin et al, 2000) and in vivo (Roan & Waters, 2011).…”

Challenges in ARDS Definition, Management, and Identification of Effective Personalized Therapies

“…After inspiration, pleural pressure decreases, resulting in tensile stress on the extracellular matrix and an increase in capillary size but also compressive stress, which reduces capillary size. Evidence suggests that tensile stress is less harmful than compressive stress [ 77 , 78 ].…”

Acute liver injury in COVID-19 patients hospitalized in the intensive care unit: Narrative review

“…Collectively, it becomes evident from the above that MV may exert negative effects on liver function in terms of both mechanics and hemodynamics, as well as from a neurohumoral and metabolic perspective[ 89 ].…”