Clamping the endotracheal tube

OVERVIEW

Clamping the endotracheal tube (ETT) may be performed during circuit disconnection and reconnection to prevent lung recruitment and reduce spread of respiratory droplets and aerosols.

USES

Consider clamping the ETT during circuit disconnection and reconnection to:

1. Prevent derecuitment and hypoxaemia
   • E.g.  in NICU/PICU settings where small children are especially prone to lung decrecruitment
   • E.g. in adult ICUs for pateints with ARDS
2. Limit dispersion of exhaled aerosols and droplets in patients with suspected respiratory infections
   • E.g. to mitigate infection transmission risk for patients with suspected or confirmed COVID19

Situations where this may be required:

• Transitioning between bag-valve apparatus and mechanical ventilator (e.g. following intubation or if troubleshooting the ventilator)
• Transitioning between mechanical ventilators (e.g. before or after patient transport)

DESCRIPTION

• a flat-edged metal clamp, ideally an ECMO clamp, should be used.

METHOD OF USE

• Ensure patient is adequately sedated such that they are not breathing spontaneously – neuromusclar blockade is usually also approrpriate
• Use appropriate clamp (e.g. metal ECMO clamp)
• Clamp ETT above pilot balloon tube and below ETT hub, ensuring ETT is fully occluded
• Perform disconnection and reconnection (in <5 seconds)
• Remove clamp
• Check that ETT is undamaged and that normal ventilation resumes

CONTRAINDICATIONS

• Patients who are awake, aware, and/or spontaneously breathing
• Use of reinforced ETT
  • never clamp a reinforced ETT as deformation leads to persistent increased airway resistance
• Incorrect clamp (e.g. plastic or clamp  with sharded edges)

COMPLICATIONS

• Hypoxia and hypercapnia from delayed oxygen reconnection
• Distress from airway obstruction in aware patients
• Negative pressure pulmonary oedema from forceful inspiration against an obstructed ETT in spontaneously breathing patients (Savaie, 2021)
• Aspiration of supraglottic contents around the ETT cuff from forceful inspiration against an obstructed ETT in spontaneously breathing patients (Savaie, 2021)
• Damage to ETT (especially reinforced ETTs)
• Risk of cuff malfunction if pilot balloon or pilot balloon tubing is inadvertently clamped
• Circuit connection/ reconnection becomes more complicated and more prone to errors

OTHER INFORMATION

Infection transmission

• ETT clamping may mitigate against infection transmission risk in patients with suspected respiratory infections (e.g. COVID19) by limiting dispersion of exhaled aerosols and droplets based on face validity.
• Published evidence is lacking.
• Potential infection control benefits may be redundant if other prevention measures are used (e.g. use of appropriate PPE and environmental modification)

Prevention of recruitment

• ETT clamping can maintain PEEP during circuit disconnection (Turbil et al, 2020)
• Clamping the ETT at PEEP 15 cmH20 preserves FRC when measured by CT lung or P-V loop methods compared with PEEP withdrawal from circuit disconnection (Lu et al, 2006). 
• Note that both Turbil et al (2020) and Lu et al (2006) performed  end-expiratory occlusion was performed, rather than end-inspiratory occlusion, asthey were primarily investigating PEEP.
• Clamping at end-inspiration maintains higher airway pressures than clamping at end-expiration (Madden et al, 2016)

Type of ETT used

• There is no change in ETT resistance before and after ETT clamping with standard plastic nasal and oral ETTs (Turbil et al, 2020)
• Reinforced ETTs remain deformed after clamping with markedly increased airway resistance (Turbil et al, 2020)

Type of clamp used

• ECMO clamps result in the least decay in airway pressure, followied by other flat-edged metal clamps (Turbill et al, 2020).
• Plastic clamps are ineffective and result in total loss of airway pressure within seconds (Turbill et al, 2020).

Tamponade therapy for pulmonary haemorrhage

• ETT clamping (for 15 hours) with ECMO support has been described to tamponade therapy of life-threatening pulmonary haemorrhage (Lee et al, 2018)

References

FOAM and web resources

• Reid C. Why would you clamp a tracheal tube? Greater Sydney Area HEMS. 2015. Available at: https://sydneyhems.com/2015/08/24/why-would-you-clamp-a-tracheal-tube/ 
• Schauf, M. Clamp the et tube! EMS Airway. 2021. Available at: https://emsairway.com/2021/02/18/clamp-the-et-tube/

Journal articles

• Lee CF, Huang CT, Ruan SY. Endotracheal tube clamping and extracorporeal membrane oxygenation to resuscitate massive pulmonary haemorrhage. Respirol Case Rep. 2018;6(5):e00321. Published 2018 Apr 6. doi:10.1002/rcr2.321 https://onlinelibrary.wiley.com/doi/10.1002/rcr2.321 
• Lu Q, Constantin JM, Nieszkowska A, Elman M, Vieira S, Rouby JJ. Measurement of alveolar derecruitment in patients with acute lung injury: computerized tomography versus pressure-volume curve. Crit Care. 2006;10(3):R95. doi:10.1186/cc4956 https://ccforum.biomedcentral.com/articles/10.1186/cc4956 
• Madden M, Andrews P, Lear G, Habashi N. Clamping the endotrachael tube using optimal clamping technique prior to disconnection maintains airway pressure reducing risk of derecruitment. Respiratory Care. 2016;61(10):pOF42-OF42. [abstract]
• McCormick T. Clamp to prevent collapse. Anaesthesia. 2010;65(8):861-862. doi:10.1111/j.1365-2044.2010.06436.x https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/10.1111/j.1365-2044.2010.06436.x 
• Savaie M. Does endotracheal tube clamping during intubation of COVID-19 patients increase the risk of negative pressure pulmonary edema? Can J Anaesth. 2021 Jan;68(1):165. doi: 10.1007/s12630-020-01833-y. Epub 2020 Oct 13. PMID: 33051792; PMCID: PMC7553727. 
• Turbil E, Terzi N, Schwebel C, Cour M, Argaud L, Guérin C. Does endo-tracheal tube clamping prevent air leaks and maintain positive end-expiratory pressure during the switching of a ventilator in a patient in an intensive care unit? A bench study. PLoS One. 2020;15(3):e0230147. Published 2020 Mar 11. doi:10.1371/journal.pone.0230147 https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0230147