A 75-year-old woman has been intubated for 7 days for communityacquired pneumonia. She is placed on a spontaneous breathing trial on ventilator settings of:
What is the most accurate explanation of how breaths are cycled (initiated or terminated) on this ventilator mode?
A. Breaths are initiated based on a set respiratory rate and inspiratory:expiratory ratioCorrect Answer: B
Pressure support breaths are cycled from inspiratory to expiratory when the patient’s inspiratory flow reaches a set percentage of the peak inspiratory flow, often 25% of peak inspiratory flow by default (answer B is correct). Pressure assist-control, a form of continuous mandatory ventilation, cycles based on a set inspiratory time (answer A is incorrect). Volume assist-control, a form of continuous mandatory ventilation, cycles when a breath reaches a target TV, the time for which is dictated by an inspiratory flow rate (answer C is incorrect). Neurally assisted ventilation coordinates inspiratory support with diaphragmatic muscular effort (answer D is incorrect). There are no modes that are terminated by reaching a peak inspiratory flow (answer E is incorrect).
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