Lung Recruitment Manoeuvres in ARDS

OVERVIEW

Recruitment manoeuvres are transient, sustained increases in transpulmonary pressure designed to open up collapsed airless alveoli.

• Primarily used in severe acute respiratory distress syndrome (ARDS)
• They can be used as part of an open lung approach (OLA) to mechanical ventilation
• Their role, and how they should be performed, remains controversial and should not be considered part of routine practice

RATIONALE

De-recruitment can occur due to:

• low tidal volume (TV) ventilation
• inadequate postive end-expiratory pressure (PEEP)
• or use of high FiO2 (absorption atelectasis)

During tidal ventilation 3 distinct lung zones are produced, associated with different types of ventilator-induced lung injury (VILI):

1. dependent
   • collapsed throughout tidal ventilation despite high levels of PEEP
   • causes chronic collapse injury
2. intermediate
   • cyclic collapse and re-expansion with each breath
   • causes shear induced injury (atelectrauma)
3. least dependent
   • regions that remain inflated through out tidal ventilation and can be over inflated by TV of > 6mL/kg and plateau pressures exceeding > 30-35cmH2O
   • causes volutrauma and barotrauma

All of these mechanisms:

• can increase cytokine release (biotrauma), and
• contribute to risk of multi-organ failure and mortality

Recruitment manoeuvres are used to open up collapsed lung, and PEEP is used to prevent cyclic collapse as part of an Open lung approach to ventilation to:

• increase end-expiratory lung volume
• improve gas exchange (especially oxygenation)
• decrease VILI

METHODS

Multiple methods have been described, including:

• 40 cmH20 for 30 seconds (Arnal et al, 2011)
  • Use pressure controlled ventilation
  • Set respiratory rate to zero and turn off apnoea alarm
  • increase PEEP to 40 cmH20 for 40 seconds
  • most recruitment occurs in the first 10s, with haemodynamic compromise occurring later
• 3 consecutive sighs/min with a plateau pressure of 45cmH2O
• 2 minutes of peak pressure of 50cmH2O and PEEP above upper inflection point (obese/trauma patients may require >60-70cmH2O)
• long slow increase in inspiratory pressure up to 40 cmH2O (RAMP)
• stepped increase in pressure (e.g. Staircase Recruitment Manoeuvre (SRM) below)

Other information

• Following the RM, there are multiple methods of determining optimal PEEP.
  • e.g. set PEEP at 25 cmH20, then decrease by 2cm increments, checking compliance and/or SpO2 at each setting to determine “optimal PEEP”
• Patients should be monitored for adverse effects (e.g. haemodynamic instability, barotrauma) during the performance of RM
• Repeat RMs can be performed for subsequent derecruitment
• recruitment can also be achieved without performing a recruitment manoeuvre per se, for instance by:
  • removal of mucus plugs (suction, bronchoscopy)
  • chest physiotherapy
  • proning

ADVANTAGES AND DISADVANTAGES OF RECRUITMENT MANOERUVRES

Advantages include:

• improved gas exchange
• improved compliance
• cheap
• quick
• easy
• can reduce conversion to adjuncts: iNO, prostacycline, ECMO, oscillation (e.g PHARLAP trial)

DISADVANTAGES

• may require heavy sedation or paralysis
• benefit may be transient
• haemodynamic instability (decrease in preload)
• only some disease states respond
• hypercapnia
• may worsen oxygenation by shunting blood to poorly aerated regions
• may contribute to ventilator-induced lung injury (VILI) due to overdistension and repeated opening of lung
• risk of barotrauma including pneumothorax
• Staircase recruitment manoeuvres (SRM) may increase mortality in severe ARDS patients (ART trial)

EVIDENCE

The evidence base for recruitment manoeuvres is conflicting

• animal data: disparity in the effect of lung mechanics and gas exchange
• extra-pulmonary ARDS may be more amenable to recruitment than pulmonary ARDS
• oxygenation benefits found to be short lived and of uncertain longterm significance
• no studies showing patient-orientated outcome benefits
• studies confounded by by presence or absence of protective lung ventilation
• how to differentiate responders from non-responders is uncertain
• controversies: who, when, how often and for how long!
• The ART trial published in 2017 used a staircase recruitment manoeuvre (SRM) to target optimal static compliance as part of an open lung approach to lung ventilation and found that mortality was increased.
• The PHARLAP trial (2019) was stopped early due to loss of equipoise following the ART trial. Although underpowered, the intervention (which include SRM) was associated with less use of rescue therapies for hypoxaemia (ECMO, iNO, and prone ventilation) at the cost of increase dysrhythmias.
• Two systematic reviews of recruitment manoeuvres (Pensier et al, 2019; Cui et al, 2020), that included data from the ART and PHARLAP trials, found:
  • no improvement in mortality
  • improvement in oxygenation
  • reduced use of rescue therapies for hypoxaemia
  • increased rates of haemodynamic compromise
  • high heterogeneity among trials, which limits the strengths of

The ART and PHARLAP trials are discussed in more detail, along with other evidence, in the Open lung approach to ventilation page.

STAIRCASE RECRUITMENT MANOEUVRE (SRM)

This is the approach described by Hodgson et al (2011)

• other approaches to SRM include targetting optimal static compliance rather than optimal SpO2 (e.g. ART trial)

Indications

• severe ARDS of <1 week duration
• other patients considered on an individualised basis

Contraindications

• Circulatory instability – ensure fluid and inotrope resuscitation complete with stable BP above target
• Pneumothorax or other air leaks (pneumomediastinum, etc) (present or recent)
• High risk of pneumothorax (e.g. necrotising lung infection, lung cysts, etc)
• ventilated ARDS present >1 week (poor responders) are a relative contra-indication

Procedure

• using pressure controlled ventilation adjust FiO2 to target SaO2 90-92%
• set  Pi to 15 cm H2O above the PEEP and maintain this difference
• increase PEEP in a stepwise manner to 20, then 30 and then 40 cm H2O with adjustments made every two minutes (i.e. Pi will reach 55 cmH20)
• reduce PEEP to 25, then 22.5, then 20, then 17.5 or then an absolute minimum of 15 cm H2O every three minutes until a decrease in SaO2 ≥ 1% from maximum SaO2 is observed (the derecruitment point)
• increase PEEP  to 40 cm H2O for one minute then return to a PEEP level 2.5 cm H2O above the derecruitment point (the optimal PEEP)
• then adjust to tidal volume ≤ 6 mls/kg IBW and a plateau pressure ≤ 30 cm H2O, tolerate permissive hypercapnia if pH >7.15, can increase RR up to 38/min (max)

SRM should be stopped if:

• HR < 60 or > 140/min
• new dysrhythmia
• SBP <80 mmHg
• SaO2 < 85% (mild desaturation during the procedure does not indicate a failed response to SRM)

CONCLUSION

Recruitment manoeuvres (RM) should not be performed routinely in the management of ARDS.

• RMs may be performed by clinical experts in select patients (e.g. refractory hypoxaemia) deemed likely to benefit from the intervention as part of an open lung approach to ventilation
• Alternative, simpler, RMs (such as 40 cmH20 PEEP for 30s) may be preferred to SRMs due to increased mortality observed in the ART trial

References and Links

LITFL

• Open lung approach to ventilation
• Positive End-expiratory Pressure (PEEP)

Journal articles

• Amato MB, Barbas CS, Medeiros DM, Magaldi RB, Schettino GP, Lorenzi-Filho G, et al. Effect of a protective-ventilation strategy on mortality in the acute respiratory distress syndrome. N Engl J Med 1998;338(6):347–354. [pubmed]
• Arnal JM, Paquet J, Wysocki M, et al. Optimal duration of a sustained inflation recruitment maneuver in ARDS patients. Intensive Care Med. 2011;37(10):1588–1594. doi:10.1007/s00134-011-2323-0 [pubmed]
• ART investigators writing group. Effect of Lung Recruitment and Titrated Positive End-Expiratory Pressure (PEEP) vs Low PEEP on Mortality in Patients With Acute Respiratory Distress Syndrome: A Randomized Clinical Trial. JAMA. 2017; 318(14):1335-1345. [pubmed]
• Brower RG, Morris A, MacIntyre N, Matthay MA, Hayden D, Thompson T, et al. Effects of recruitment maneuvers in patients with acute lung injury and acute respiratory distress syndrome ventilated with high positive end-expiratory pressure. Crit Care Med 2003;31(11):2592–2597. [pubmed]
• Cui Y, Cao R, Wang Y, Li G. Lung Recruitment Maneuvers for ARDS Patients: A Systematic Review and Meta-Analysis. Respiration. 2020;99(3):264–276. doi:10.1159/000501045 [pubmed]
• Hess DR. Recruitment Maneuvers and PEEP Titration. Respir Care. 2015;60(11):1688–1704. doi:10.4187/respcare.04409 [pubmed]
• Hodgson CL, Tuxen DV, Davies AR, Bailey MJ, Higgins AM, Holland AE, Keating JL, Pilcher DV, Westbrook AJ, Cooper DJ, Nichol AD. A randomised controlled trial of an open lung strategy with staircase recruitment, titrated PEEP and targeted low airway pressures in patients with acute respiratory distress syndrome. Crit Care. 2011;15(3):R133.PMC3219001.
• Hodgson C, Keating JL, Holland AE, Davies AR, Smirneos L, Bradley SJ, Tuxen D. Recruitment manoeuvres for adults with acute lung injury receiving mechanical ventilation. Cochrane Database Syst Rev. 2009 Apr 15;(2):CD006667. PMID: 19370647. [Free Full Text]
• Lapinsky SE, Mehta S. Bench-to-bedside review: Recruitment and recruiting maneuvers. Critical care (London, England). 9(1):60-5. 2005. [pubmed]
• Pelosi P, Gama de Abreu M, Rocco PR. New and conventional strategies for lung recruitment in acute respiratory distress syndrome. Crit Care. 2010;14(2):210. [pubmed]
• Pensier J, de Jong A, Hajjej Z, et al. Effect of lung recruitment maneuver on oxygenation, physiological parameters and mortality in acute respiratory distress syndrome patients: a systematic review and meta-analysis. Intensive Care Med. 2019;45(12):1691–1702. doi:10.1007/s00134-019-05821-9 [pubmed]
• Philpot SJ, Pilcher DV, Graham SM, Snell GI. Lung recruitment manoeuvres should be considered when assessing suitability for lung donation. Crit Care Resusc. 2012 Sep;14(3):244-5. [pubmed]
• Tuxen D, Hodgson C (2010) Lung recruitment: who, when and how? Crit Care Resus, 12(3):139-141. [pubmed]