Lung Recruitment Maneuver

Original Editor - User Name

Top Contributors - Manisha Shrestha, Kim Jackson and Uchechukwu Chukwuemeka  

Introduction

Recruitment generally mean opening up collapsed alveoli to improve oxygenation. Lung recruitment maneuver is the maneuver in which temporary airway pressure is increased during mechanical ventilation so as to open up the collapsed alveoli and enhance alveolar unit involving in tidal ventilation to improve the oxygenation.(1) If recruitment maneuver is combined with the administration of higher PEEP (positive end expiratory pressure) via mechanical ventilator, it is known as open lung ventilator strategy.(1)

In the study done by Dean HR (2015), the recruitment of lungs can be done by other techniques rather than recruitment maneuver. Other techniques include removal of mucus plug and positioning of the patient which ultimately improve opening up of alveoli and enhance oxygenation. Therefore, methods to accomplish alveolar recruitment mentioned by Dean HR (2015) are:

• Treatment of underlying disease process: removal of airway obstruction, treatment of infection.

• Sustained inflation followed by decremental PEEP.

• Step-wise recruitment ( incremental PEEP)

• Airway pressure release ventilation

• High frequency oscillation ventilation

• Sigh

• Prone positioning  

How does it help?

This maneuver re‐open collapsed field of the lungs by temporarily elevating intrapulmonary pressure to

levels higher than those achieved during tidal ventilation. (1)

Advantages of lung recruitment maneuver

• Increase the number of alveoli in dependent part of lungs participating in gas exchange.
• Increase lung compliance. (6)
• Reduced intrapulmonary shunt improving gas exchange in pulmonary capillaries.(6)

Disadvantages of lung recruitment maneuver

• Short‐term physiological benefit. (1)
• Increase intra-thoracic pressure compromising hemodynamic due to reduce venous return and cardiac output for short duration.(1)
• Hypotension and de-saturation. (1) 
• Overdistension of alveoli. (6)
• No significant change in duration of mechanical ventilation, ICU stay, and hospital stay after recruitment maneuver. (1)
• Injury to the pulmonary epithelium due to increased in intrapulmonary pressure (barotraumas) leading pneumothorax, pneumomediastinum, or subcutaneous emphysema.(2)  

Lung recruitment maneuver and Acute respiratory distress syndrome (ARDS).

Definition

ARDS is the life threatening syndrome characterized by diffuse pulmonary inflammation,hypoxemia, and respiratory distress. (5) Please go to this links for more detail

(https://www.physio-pedia.com/Acute_Respiratory_Distress_Syndrome_(ARDS)

According to the American-European Consensus Conference (AECC) 1994, ARDS was defined as: the acute onset of respiratory failure, bilateral infiltrates on chest radiograph, hypoxemia as defined by a PaO2/FiO2 ratio ≤200 mmHg, and no evidence of left atrial hypertension or a pulmonary capillary pressure <18 mmHg (if measured) to rule out cardiogenic edema.(5)

Evidences

About 14 % of COVID-19 cases are severe and 5% may require ICU support. One of the common secondary complications to COVID-19 in severe cases is ARDS.

Evidence shows that lung recruitment maneuver along with other co-intervention like higher PEEP ventilation strategy and lung protection strategy (ventilation strategies that combine low tidal volumes and relatively high respiratory rate by applying positive end expiratory pressure in relation with appropriate FiO2) has shown benefit to the patient with ARDS than recruitment maneuver alone.(1,6) Even though the significance of recruitment maneuver in ARDS patient is low, WHO has choosen recruitment maneuver as relative intervention with high continuous positive airway pressure (CPAP) (30–40 cmH2O), progressive incremental increases in PEEP with constant driving pressure, or high driving under supervised monitoring of hemodynamics and considering benefit VS risk. Recruitment maneuver should be immediately discontinued there is any signs of no improvement in oxygenation, hypotension or barotrauma.(4) And stepwise recruitment maneuver is recommended rather than sustained inflation as it helps in balance recruitment against over-distension.(2)

For more information you can go to this video link

https://www.youtube.com/results?search_query=+recruitment+manuever

The significance of recruitment maneuver in patient with ARDS shown to be low. It may be because of the following reasons:

• In ARDS, alveoli of dependent lung field are de-recruited because it is filled with fluid from the inflammation and edema rather than collapsed. (2)
• In ARDS, lung field are heterogeneously participating in gas exchange and an increase in alveolar pressure results in over-distention of spared alveoli which may cause barotraumas.(2)

Prone positioning

Prone position is the recruitment technique in which patient is made to lying on prone to open up the non-aerated alveoli in homogenous manner to improve oxygenation (2). WHO has suggested to placed the patient with ARDS following COVID-19 in prone position for 12-16 hours in a day.(4)

How does it help?

• Sponge model

Pleural pressure is the sum of all forces exerting to compress the alveolus including the weight of tissue above the alveolus and the transmitted pressure across the diaphragm from the abdomen. Decrease in pleural pressure helps in opening up of alveoli. In prone position, pleural pressure decrease in dorsal part of lung, increasing opening up of alveoli. This is known as Sponge model and was first described by Gattinoni et al. (7)

• Lungs are asymmetrical in prone and supine position due to the ventral intra-thoracic structures like heart, compression of subjacent lung parenchyma and also due to displacement of abdominal content cranially toward diaphragm mainly in sedated patient due to loss of diaphragmatic tone.In prone position due to the asymmetry of lungs with more lungs field available in dorsal part,recruiting more alveoli and thus increase ventilation. Pulmonary perfusion is relatively equal in both positions thus help in ventilation-perfusion matching and ultimately enhance oxygenation.(7)

Complication

There are relative complications of prone positioning which can be eliminating if the procedure is done by experienced health staff. It includes:

• Airway obstruction and endo-tracheal tube dislodgement

• Hypotension and arrhythmias

• Loss of venous access

• Facial and airway edema

• A greater need for paralysis and sedation(7)

Contraindication

Absolute contraindication

• Recent sternotomy or abdominal incisions.

• Unstable vertebral fractures

• Significantly increased intracranial pressures(7)

References

1. Bhattacharjee, S., Soni, K.D. and Maitra, S., 2018. Recruitment maneuver does not provide any mortality

benefit over lung protective strategy ventilation in adult patients with acute respiratory distress syndrome: a

meta-analysis and systematic review of the randomized controlled trials. Journal of intensive care, 6(1),  

Resources

You can also visit following link

• https://physio-pedia.com/Respiratory_Management_of_COVID_19 https://www.youtube.com/watch?v=FS4t5w1eCYw

References

Original Editor - Manisha Shrestha Top Contributors - Manisha Shrestha, Kim Jackson and Uchechukwu Chukwuemeka