Recruitment Manoeuvresfor the improvement of oxygenation

Alex Yartsev 09/02/2010

Recruitment Manoeuvres

• An administration of high ventilation pressure to a patient for a brief period of time

• Aim is to reinflate collapsed lung tissue, thus “recruiting” that tissue

• Aim is also to prevent “de-recruitment” by applying PEEP after the manoeuvre

• The desired outcome is improved oxygenation• There are specific indications

When do you need RM

• BROADLY: when the patient has enough collapsed alveoli to impact on their oxygenation

The physiology• There are both inflating and collapsing forces acting

on the alveoli:• COLLAPSING:• Surface tension• Recoil pressure of the

lungs• +1cmH2O alveolar

pressure (expiration)• Gas absorption

• INFLATING:• Surfactant• Negative pleural

pressure• -1cmH2O alveolar

pressure (inspiration)• Nitrogen splinting

Causes of alveolar collapse

• Loss of surfactant eg. ALI/ARDS• Positive pleural pressure eg. pneumothorax• Negative alveolar pressure eg. suctioning• Gas reabsorption eg. sputum plugging• Loss of nitrogen splinting eg. high FiO2

Indications for RM

• ARDS / Acute Lung Injury• Patients with “secondary ARDS” (eg from abdominal sepsis) seem to

respond better than those with “primary” ARDS eg. from pneumonia– Bilateral pulmonary infiltrates– PaO2/FiO2* <300 = ALI – PaO2/FiO2 <200 = ARDS

• Atelectasis during general anaesthesia• After suctioning the ETT

Contraindications for RM

• Hemodynamic compromise: recruitment manoeuvres cause a transient loss of venous return, compromising cardiac output.

• Existing barotrauma• Increased intracranial pressure• Predisposition to barotrauma:

– Apical bullous lung disease– Focal lung pathology eg. lobar pneumonia

Determining the “recruitability” of lungs

• CT scans on low and high PEEP: compare the volume of aerated regions (Gattinoni 2006)

• Effect of PEEP: compare PEEP 5 and PEEP 15; the change in the percentage of nonaerated lung tissue is correlated with the percentage of potentially recruitable lung – and can be calculated from the changes in PaO2/FiO2 ratio (Maggiore 2001)

• Pressure- volume curves: oversimplify the situation; heterogeneity of lung tissue in an ARDS lung does not lend itself well to being reduced a single curve

Types of Recruitment Manoeuvres

• CPAP with increased pressures• Pressure-controlled ventilation on high PEEP

• Advanced recruitment manoeuvres:– Prone ventilation to recruit dorsal lung units– High frequency oscillatory ventilation (lung protective)– Airway pressure release ventilation, low PEEP and low tidal

volume, with I:E of 4:1

Aims of recruitment manoeuvres

Atelectasis andDerecruitmentThus,HypoxiaVQ mismatchInjury due to repeated opening/closing of alveoli

Overdistension, thusSurfactant degradationMechanical lung injuryHigh oxygen exposure

Consequences of Recruitment Manoeuvres• Increased oxygenation• Stretch reflex of the alveoli, which causes Type II respiratory

cells to release more surfactant• Increased intrapulmonary shunt• Barotrauma; overdistension of already well-ventilated lung

regions• VILI due to the above• Increased pulmonary arterial pressure• Decreased cardiac output• Increased intracranial pressure

– The hemodynamic consequences seem to normalise 10-20mintues after the manoeuvre ( Bein et al 2002)

Some basic RM protocols

• CPAP 40cmH2O for 40 seconds (Girgis et al 2006 resp care)

• CPAP 40cmH2O for 30 seconds (Brower et al. 2003 crit care med)

• Pressure controlled ventilation with Pplat 45cm H2O, PEEP of 5, I:E 1:1 and rate of 10 (Gattinoni et al 2006 NEJM)

• Volume control ventilation with 20cmH2O of PEEP, allowing Ppeak to go up to 40cmH2O, for 2 minutes, and then gradually reducing PEEP (Celebi et al 2007 Anaesth Analg)

PEEP after recruitment• Everyone seems to agree that appropriate PEEP following

recruitment manoeuvres is critical for SUSTAINED improvement • Nobody agrees on how to determine appropriate PEEP– Generally, it is recommended (Hickling 2001) to

gradually decrease PEEP until there is a fall in PO2; this is a “decremental PEEP trial”

– PEEP is decreased by 2cmH2O every 4 minutes– A fall in PO2 by over 10% indicates that there is

derecruitment– PEEP is then set to just above the level at which

derecruitment occurs– For Girgis et al (2006) this strategy resulted in 4 hrs of

improved oxygenation

Monitoring during RM

• Discontinue the manoeuvre if:– Systolic BP decreases by 30mmHg– SaO2 decreases by 5% – Heart rate increases by 20bpm– Arrhythmia is seen

Whats the best RM manoeuvre?

• Numerous RM protocols are published• Small numbers, different outcome measures,

patient heterogeneity• Decremental PEEP is the only strategy which

shows benefit, i.e. prolongs the oxygenation benefit of RMs

Who is most likely to benefit?

• Atelectatic post-op patient: normal lung

• Ventilated patient who is hypoxic after suctioning

• ARDS patient in the early stages

Who is least likely to benefit?

• Patient with pneumonia• Primary ARDS (pneumonia, toxic gas

inhalation, lung contusion)• Late ARDS, with organization / fibrosis

Do recruitment manoeuvres improve outcomes ?Whats the evidence?

• A 2009 Cochrane review by Hodgson et al:– 7 trials reviewed, total N = 1170– Did not differentiate between different RM strategies, simply

compared RM vs no RM in ARDS– No significant difference on 28th day mortality– No statistical difference in risk of barotrauma– RMs did indeed cause significantly improved oxygenation for brief

periods, but this was not sustained.– CONCLUSION: “There is not evidence to make conclusions on whether

recruitment manoeuvres reduce mortality or length of ventilation in patients with ALI or ARDS.”

In summary:• RMs help in early ARDS, post-op atelectasis, and after

suctioning • Not to be used in patients with barotrauma,

hemodynamic compromise, bullous lung disease or head injury

• Monitor carefully during and after the manoeuvre• Use a decremental PEEP trial to establish minimum

effective PEEP

• Do not expect long-term gains in oxygenation or lung mechanics

References

• Oxford Textbook of Critical Care (CIAP)• Ohs Intensive Care Manual (6th ed.)• Guyton and Hall Medical Physiology (11th ed)• Amato et.al., Lung Recruitment in Patients with the Acute Respiratory Distress Syndrome NEJM

volume 354:1775-1786 Number 17 April 2006• Tusman G, Bohm SH, Vazquez de Anda GF, do Campo JL, Lachmann B (1999) `Alveolar recruitment

strategy' improves arterial oxygenation during general anaesthesia. Br J Anaesth 82:8–13• Meade MO, Guyatt GM, Cook DJ (2002) Physiologic randomized pilot study of a lung recruitment

study in acute lung injury. Am J Respir Crit Care Med 165:A683 • Maggiore et al Alveolar Derecruitment at Decremental Positive End-Expiratory Pressure Levels in

Acute Lung Injury, Am. J. Respir. Crit. Care Med., Volume 164, Number 5, September 2001, 795-801• Hodgson et. al., Recruitment manoeuvres for adults with acute lung injury receiving mechanical

ventilation. Cochrane Database of Systematic Reviews 2009, Issue 2. Art. No.: CD006667. DOI: 10.1002/14651858.CD006667.pub2.

More references• Bein T, Kuhr LP, Bele S, Ploner F, Keyl C, Taeger K. Lung recruitment

maneuver in patients with cerebral injury: effects on intracranial pressure and cerebral metabolism. Intensive Care Med 2002;28:554–558.

• Moran et al, Recruitment manoeuvres in acute lung injury/acute respiratory distress syndrome Eur Respir J 2003; 22:37s-42s

• Dyhr et al, Lung recruitment manoeuvres are effective in regaining lung volume and oxygenation after open endotracheal suctioning in acute respiratory distress syndrome Critical Care 2003, 7:55-62

• Tusman et al, Alveolar recruitment strategy improves arterial oxygenation during general anaesthesia British Journal of Anaesthesia, Vol 82, Issue 1 8-13, 1999