We all intubate patients with cuffed tubes, but we’re far too busy and important to fart around measuring tracheal tube cuff pressures when we’re saving lives right? Surely something the ICU nurses can sort out between ‘eye care’ and swabbing for MRSA.
The modern ‘high volume low pressure’ cuff has certainly led us to worry less about cuff pressures, and in frontline critical care specialties like emergency medicine and pre-hospital and retrieval medicine it’s the last thing on our minds. However we should consider the accumulating pool of evidence that tells us:
- Physicians are hopelessly poor at estimating cuff pressures based on palpating the pilot balloon
- Cuff pressures are frequently very high
- Tracheal mucosal injury can occur even after short term intubation (a few hours)
- When the pressure in the cuff exceeds 22 mm Hg, blood flow in the tracheal mucosa begins decreasing
- Tracheal mucosal blood flow reduces markedly when the pressure reaches 30 mm Hg
- When the pressure in the cuff reaches 50 mm Hg for 15 minutes, ischemic injury to the tracheal mucosa can occur
A study from China tested the hypothesis that an appropriate tracheal tube cuff (ETTc) pressure even in short procedures would reduce endotracheal intubation–related morbidity. They compared bronchoscopic appearance of tracheal mucosa, and patient symptoms of tracheal injury, in two groups of elective surgical patients anaesthetised and intubated between 120 and 180 minutes: a control group without measuring ETTc pressure, and a study group with ETTc pressure measured and adjusted to a range 15-25 mmHg. The endoscopist was blinded to the study group allocation.
The mean ETTc pressure measured after estimation by palpation of the pilot balloon of the study group was 43 +/- 23.3 mm Hg before adjustment (the highest was 210 mm Hg), and 20+/- 3.1 mm Hg after adjustment (p< 0.001). The incidence of postprocedural sore throat, hoarseness, and blood-streaked expectoration in the control group was significantly higher than in the study group. As the duration of endotracheal intubation increased, the incidence of sore throat and blood-streaked expectoration in the control group increased. The incidence of sore throat in the study group also increased with increasing duration of endotracheal intubation. Fiberoptic bronchoscopy showed that the tracheal mucosa was injured in varying degrees in both groups, but the injury was more severe in the control group than in the study group.
So..time to get a cuff manometer for your ED or helicopter? Perhaps you already have one. What do you think?
Correlations Between Controlled Endotracheal Tube Cuff Pressure and Postprocedural Complications: A Multicenter Study
Anesth Analg. 2010 Nov;111(5):1133-7
Cuff pressure in flight
Paediatric cuff pressures