Lung Recruitment Maneuvers in Acute Respiratory Distress Syndrome

By Richard H. Kallet, MS, RRT, FAARC, FCCM, Director of Quality Assurance, Respiratory Care Services, San Francisco General Hospital. Mr. Kallet reports no financial relationships relevant to this field of study.

A recruitment maneuver (RM) is the technique of briefly increasing alveolar pressure to levels in excess of what normally is recommended to reopen collapsed peripheral airways and alveoli so that both resting lung volume, or functional residual capacity (FRC), and oxygenation are restored.1 Moreover, amelioration of sheer injury through reversal of atelectasis is a major component in preventing ventilator-induced lung injury (VILI) in patients with acute respiratory distress syndrome (ARDS). This special feature will provide a brief overview of the physiologic foundation and history of RMs as well as discuss its clinical application.

Physics and Physiology of the Recruitment Maneuver

The RM is inextricably related to the pulmonary pressure volume (compliance) curve and the concept of hysteresis. Moving the lungs from a relatively collapsed to a fully inflated state produces a leftward shift in the pressure-volume relationship (that is, improved compliance).1 During subsequent deflation to FRC, tidal ventilation requires a lower driving pressure that lessens the risk for VILI. In essence, the RM is the same phenomenon that occurs with the first postnatal breath. At birth, the initial recruitment of the gasless lung requires a critical opening pressure of -40 cm H2O to begin inflation and pressures approaching -80 cm H2O to achieve full inflation.2 Similarly, inflation of a collapsed, excised lung (at residual volume) requires a lower critical opening pressure of 20 cm H2O; thereafter, recruitment proceeds unevenly until full inflation is achieved at a transpulmonary pressure of 40 cm H2O.2

Reversal of significant lung collapse not only requires high inflation pressures, but those pressures must also be sustained for a period of time. This temporal component is particularly important in ARDS. Lung recruitment is determined by numerous factors, including the surface tension, viscosity and film thickness of the airway lining fluid, airway radius, axial wall traction exerted by the surrounding alveoli, and the presence of surfactant.3Increased lining fluid surface tension raises the applied airway pressure necessary to reopen collapsed airways, while an increased viscosity (as with protein-rich pulmonary edema fluid) prolongs the time necessary to reopen sequentially collapsed airways.3 The opening pressure must also counter the superimposed weight of the edematous lung itself, the mediastinum and chest wall, as well as disperse edema fluid and cellular debris residing in the small airways and alveoli.1

For more plz read at following link.

Regards

https://www.ahcmedia.com/articles/63470-lung-recruitment-maneuvers-in-acute-respiratory-distress-syndrome

we usually use the high PEEP method

Yes, PEEP and various modes of the plateau pressure may be very effective. I personally believe that, apart from some forms of the spontaneous negative pressure ventilation in addition to PEEP, FREQUENT changes of the position of the patient  so that the pathologically collapsed lungs will be higher from well ventilated sections, is more physiological and less traumatic. Of course, it may be hard to manage and should not endanger macro hemodynamic, local circulation and other physiological functions that may be compromised in those patients.

Hi, 

Perhaps this might help you! 

1) Güldner A, Kiss T, Serpa Neto A, Hemmes SNT, Canet J, Spieth PM, et al. Intraoperative Protective Mechanical Ventilation for Prevention of Postoperative Pulmonary Complications. Anesthesiology. 2015 Sep;123(3):692–713.

2) Optimum PEEP During Anesthesia and in Intensive Care is a Compromise but is Better than Nothing (see below). 

Very nice Pro / Con debate 

Greetings from Rotterdam

Frank

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A small point regarding the first answer: a successful recruitment maneuver enlarges the (ventilated part of the) lungs. This means there is a higher gas volume for any given airway pressure - hence the leftward shift of the pressure-volume curve. Compliance is likely to improve, providing PEEP is optimised but improved compliance will be reflected in an increased slope of the P-V curve (not the leftward shift).

Different methods available for recruitment most commonly employed are...

1.High PEEP

2.Prone ventilation