Ineffective efforts during mechanical ventilation: the brain wants, the machine declines

Excerpt

Asynchrony between patient and ventilator occurs when there is a mismatch between the patient and ventilator inspiratory and expiratory times [1]. This mismatch may be due to inspiratory and expiratory delays, which are almost inevitable with most ventilatory modes, and/or to major asynchronies such as autotriggering (the ventilator is triggered in the absence of patient effort), multiple triggering (one inspiratory effort triggers the ventilator more than once), and ineffective triggering (the patient’s inspiratory effort fails to trigger the ventilator) [1, 2]. Ineffective triggering (or ineffective efforts, IE) is a commonly encountered major asynchrony [2, 3] and may occur during either the inspiratory or the expiratory ventilator phase [4]. The incidence of IE depends on several factors such as the population studied, the ventilator settings, the sedation depth, and the sleep/awake state [2, 3, 5‐8]. de Wit et al. [9] studied a population of unselected critically ill patients within the first 24 h of mechanical ventilation and found that 27% of patients exhibited IE in more than 10% of their inspiratory efforts. In obstructive lung disease IE have been observed in up to 80% of patients [7, 8]. …