Positive expiratory pressure – Common clinical applications and physiological effects  Monika Fagevik Olsén, Louise Lannefors, Elisabeth Westerdahl  Respiratory Medicine  Volume 109, Issue 3, Pages 297-307 (March 2015) DOI: 10.1016/j.rmed.2014.11.003 Copyright © 2014 Elsevier Ltd Terms and Conditions

Figure 1 PEP when utilized to increase diminished VT and FRC in patients who hypoventilate at inadequate FRC. The achieved effect is schematically drawn as temporarily increased effect during PEP. IRV = inspiratory reserve volume, VT = tidal volume, ERV = expiratory reserve volume, RV = residual volume, FRC = functional residual capacity. Respiratory Medicine 2015 109, 297-307DOI: (10.1016/j.rmed.2014.11.003) Copyright © 2014 Elsevier Ltd Terms and Conditions

Figure 2 PEP when utilized to temporarily decrease FRC in obstructed patients with hyperinflated lungs can be an immediate functional management to improve gas exchange and to manage dyspnoea both at rest and during physical effort. Respiratory Medicine 2015 109, 297-307DOI: (10.1016/j.rmed.2014.11.003) Copyright © 2014 Elsevier Ltd Terms and Conditions

Figure 3 The PEP airway clearance technique is a cycle that includes 1) temporarily increased FRC during PEP in order to open clogged and collapsed airways to “get air behind secretions” and 2) mobilizing and evacuating secretions without the expiratory resistance. The patient may preferably be taught the Forced Expiratory Technique (FET) and effective coughing in order to mobilize, transport and evacuate the secretion. The PEP cycle is repeated several times during a treatment session. Respiratory Medicine 2015 109, 297-307DOI: (10.1016/j.rmed.2014.11.003) Copyright © 2014 Elsevier Ltd Terms and Conditions

Figure 4 Expiratory flow volume loops performed by a CF patient, first without extra corporal resistance and then against flow dependent resistances with different internal diameters in order to choose the correct size. The loops show that the 2.5 mm resistance results in a large expired volume, elative high mid-expiratory flow plateau during a large part of the expiration and a homogenized flow drop in the peripheral airways. For the moment in this patient, the optimal resistance is 2.5 mm. With the Journal's permission [13]. SEP = sustained expiratory pressure. Respiratory Medicine 2015 109, 297-307DOI: (10.1016/j.rmed.2014.11.003) Copyright © 2014 Elsevier Ltd Terms and Conditions

Figure 5 Forced expiratory flow volume curves in a CF patient, first performed conventionally without external resistance and a second superimposed curve then obtained through an external oscillatory positive expiratory pressure (OscPEP) device (Flutter VRP1®). The square indicates the therapeutical part of the forced expiratory volume range within which the flow swings generated by the OscPEP are much higher than the flow without external resistance. Re-used and modified with the permission of the author [108]. Respiratory Medicine 2015 109, 297-307DOI: (10.1016/j.rmed.2014.11.003) Copyright © 2014 Elsevier Ltd Terms and Conditions