Question 19

College answer

Aim: To explore an airway practice more common in the ICU since Covid19.
Key sources include: Procedure seen in clinical practice. CanMEDS Medical Expert.
Discussion: This is a common procedure designed to limit the aerosolization of pathogens and prevent lung de-recruitment. This procedure is especially important in NICU /PICU and in high PEEP strategies with ARDS.
Candidates did well if they gave details and rationale for the procedure and related it to their clinical practice. For example, detailing the requirements for a blunt clamp -/+ gauze squares to avoid trauma to the endotracheal tube. Candidates also gained marks if they identified common clinical scenarios and explained this in detail for example, some endotracheal tubes cannot be clamped (reinforced tubes). Other examples included an indication that this procedure is inappropriate in some patients e.g., awake, aware, and spontaneously breathing.
Candidates are encouraged to answer clinical questions in detail and provide rationale to demonstrate familiarity with aspects of clinical practice, to demonstrate clinical competency.

Discussion

What follows (and perhaps what leads) are derived from this excellent summary by LITFL.

Indications

• Pressure-related indications
  • To prevent the release of pressure in a patient who is dependent on a large amount of positive pressure for their oxygenation (preventing derecruitment and protecting the open-lung ventilation strategy)
  • To help tamponade pulmonary haemorrhage (where ECMO is use to support gas exchange, the ETT can be clamped to stop life-threatening haemoptysis)
• Aerosol-related indications
  • To prevent the release of aerosolised pathogens during ventilator circuit disconnections
  • To prevent the exposure of staff to aerosolised medications being administered continuously via a nebuliser
• Equipment position related indications
  • To prevent the displacement of an endobronchial blocker which is positioned using the ETT (by clamping, the position of the blocker is fixed against the ETT)

Contraindications

• Poor equipment choices
  • A damaged endotracheal tube (it could break!)
  • Reinforced (steel spiral wire) endotracheal tube (once kinked, those wires will not un-kink)
  • Toothed "sharded" edge clamp or some other idiotic clamp choice (eg. some kind of plastic IDC clamp, arterial forceps or towel clip)
  • Something fragile left in the ETT (eg. a suction catheter that cannot be completely withdrawn) - this could be transected and lost in the lung!
• Patient factors
  • An awake spontaneously breathing patient (this would be poorly tolerated)
  • Patients in whom pressure requirements are low (i..e were re-recruitment would be fairly effortless and there are no aerosol reasons to clamp, the added steps of clamping and unclamping would add an unnecessary cognitive load)

Detrimental clinical sequelae

• Under all circumstances:
  • Increased cognitive load by adding an extra task into an already highly charged situation could make the operators more error-prone
• If the clamp stays on for too long (eg. operator forgets to unclamp immediately):
  • Hypoxia
  • Hypercapnia
  • Atelectasis happens anyway (due to absorption)
• If the patient is even slightly awake:
  • Negative pressure pulmonary oedema (trying to inhale against an obstructed airway)
  • Valsalva-related haemodynamic instability (trying to exhale against an obstructed airway)
  • Distress
  • Aspiration of suprgalottic airway contents - if the patient generates a hugely negative intrathoracic pressure (i.e. blow atmospheric), they will suck all the disgusting gunk collecting above the cuff into their lungs, and that would not be cool.
• If the clamp is handled incorrectly
  • Damage to the ETT
  • ETT dislodgement (say the clamp catches on something during turning to/from prone position)
  • Reintubation, and all the risks associated with this

Lee, Chien‐Feng, Chun‐Ta Huang, and Sheng‐Yuan Ruan. "Endotracheal tube clamping and extracorporeal membrane oxygenation to resuscitate massive pulmonary haemorrhage." Respirology case reports 6.5 (2018): e00321.

Turbil, Emanuele, et al. "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 15.3 (2020): e0230147.

Bulleri, Enrico, et al. "Efficacy of endotracheal tube clamping to prevent positive airways pressure loss and pressure behavior after reconnection: a bench study." Intensive Care Medicine Experimental 11.1 (2023): 1-14.

Savaie, Mohsen. "Does endotracheal tube clamping during intubation of COVID-19 patients increase the risk of negative pressure pulmonary edema?." Canadian Journal of Anesthesia/Journal canadien d'anesthésie 68.1 (2021): 165-165.