Recruitment Maneuvers in ARDS

Definition

Definition is a little vague but best described as "a recruitment manoeuvre is any technique that transiently increased alveolar pressure above normal tidal ventilation (which may have included an increase in any pressure, such as plateau, peak or end-expiratory pressure) and sustained that pressure beyond the normal time."
From UpToDate: "A recruitment maneuver is the brief application of a high level of continuous positive airway pressure (CPAP) or PEEP, with the goal of recruiting non-gas exchanging parts of the lung involved with ARDS to become involved in gas exchange."

in ARDS, there is heterogeneity of lung involvement
regions may be collapsed/atelectatic and not participating in gas exchange
regions may be re-inflated by application of enough positive transpulmonary pressure
if these areas can be kept open, then gas exchange should improve and allow for decreaed FiO2 and oxygen induced toxicity

Varied in the literature, no consensus technique. Types of RMs:

Gattinoni 2006 (NEJM)
- 5, 15, and 45 cm H2O PEEP highly correlates with the percentage of lung tissue aerated after application of the pressure
- the % of recruitable lung is extremely variable and relates to greater total lung weight, poorer oxygenation, poorer compliance, and higher death rates.
Cochrane review 2016
- only low-quality evidence supported the use of recruitment manoeuvres
- improved ICU mortality (but not hospital mortality)
ART trial 2017
- N=1010. Increased 28-day all-cause mortality associated with recruitment manoeuvres to 50-60 cmH2O for patients with moderate-severe ARDS
PHARLAP trial 2019
- stopped recruitment due to ART results
- preliminary data suggested no improvement in patient-centred outcomes

There is no evidence to support the routine use of recruitment maneuvers in ARDS.

can be performed in those with ongoing severe refractory ARDS despite lung-protective ventilation strategies, or those thought to be derecruited after a specific event (bronchoscopy, circuit disconnection, etc)
example strategy could be PEEP 35 to 40 cm H2O for 40 seconds
unknown optimal frequency
can be used as part of open lung ventilation (OLV) strategy (may increase mortality in ART study)
- Low tidal volume ventilation
- recruitment maneuver is performed
- subsequent downtitration of applied PEEP to a level higher than typically used for LTTV, using PEEP optimization method
- improves oxygenation, but conflicting data on mortality. Possible harm in the ART trial.

easy to perform
cheapest method of improving oxygenation (compared to inhaled NO, prostacycline, HFOV, ECMO, prone)
range of different techniques in the literature (can be tailored)
may improve oxygenation (consistent across studies)
they are usually already paralyzed and sedated
more effective in the prone position

Writing Group for the Alveolar Recruitment for ARDS Trial (ART) Investigators. Effect of Lung Recruitment and Titrated Positive End-Expiratory Pressure (PEEP) vs Low PEEP on Mortality in Patients With ARDS: A Randomized Clinical Trial. JAMA. 2017;318(14):1335-1345. doi:10.1001/jama.2017.14171
Hodgson CL, Cooper DJ, Arabi Y, et al. Maximal Recruitment Open Lung Ventilation in ARDS (PHARLAP). A Phase II, Multicenter Randomized Controlled Clinical Trial. Am J Respir Crit Care Med. 2019;200(11):1363-1372. doi:10.1164/rccm.201901-0109OC
Deranged Physiology
LITFL
UpToDate