Pressure support ventilation By Amber and Manda
What is Pressure Support? • Pressure support is a method of assisting spontaneous breathing in patients on mechanical ventilation • Usually used during weaning due to the fact it is usually used on spontaneous modes • The patient controls the parameter of the breath, except ventilator delivers a flow until the patients peak inspiratory pressure reaches a set point (25% of the set point usually) • Tidal volumes may vary just as they would with normal breathing
PS vs Peep • Peep is the air pressure left over after expiration. Peep is used to restore FRC or functional residual capacity • FRC which is the sum of ERV and RV (expiratory reserve volume and residual volume) • FRC is one way to measure the compliance of the lung complaince • When lungs loose their compliance, higher intrapleural pressures are required to inflate the lungs to a normal volume.
Pressure support can be added to Peep to assist the patient in receiving a higher volume for each breath
Indications of PS • Indications for PSV: • Used for weaning: • Patient is switched from full ventilatory support to pressure support around and inspiratory pressure that is suffiecent to provide the same tidal volume as the mechanical ventilation. • Inspiratory pressure is then gradually reduced using the patients respiratroy rate as a guide to adequate support
Contraindications of PS • Contraindications for PSV: • Patient being hemodynamically unstable to wean • insufficentventilatory drive and neuromuscular function to initiate a spontaneous inspiratory effort. • acceptable acid base balance
References • http://www.respiratory.webege.com/Chap10.pdf • www.courses.washington.edu/med610/mechanicalventilation/mv_prinerz.html • http://www.ccmtutorials.com/rs/mv/psv.htm • http://www.rcecs.com/MyCE/PDFDocs/course/V7006.pdf