Over-inflation of the tracheal tube cuff: a case for routine monitoring

Introduction

Excessive tracheal tube cuff pressure can cause mucosal ischaemia leading to tracheal stenosis or tracheooesophageal fistulae [1] and under-inflation of the cuff has been associated with an increased risk of ventilator-associated pneumonia [2]. High-volume low-pressure (HVLP) cuffs were introduced in the early 1970s to enable tracheal wall pressure control. The use of a HVLP cuff does not however guarantee an acceptable mucosal pressure (MP) unless the intra-cuff pressure (CP) is maintained lower than 30 cmH₂O. CP was measured regularly in only 13% of intensive care units (ICU) in one region of England [3]. This prospective observational study examines the CP recorded after induction of anaesthesia and in two critical care facilities.

Method

The CP was measured in 30 sequential anaesthetised patients and 30 critically ill patients in each of two critical care facilities in one region of England. The anaesthetised group had their cuffs inflated by the operating department practitioner (ODP). The cuffs of the critically ill patients were surreptitiously checked once per patient on the ICU. The ODP and ICU nurses were unaware that the audit was taking place. If the CP was high it was reduced to 30 cmH₂O. If a leak was detected after reducing the CP then the cuff was re-inflated to just seal and the patient documented as appropriately high CP.

Results

Anaesthetised patients

The mean CP was 62 cmH₂O (range 20-120 cmH₂O, n = 30). There were six (20%) CPs above 100 cmH₂O.

Critically ill patients

The mean CP was 46 cmH₂O (range 13-120 cmH₂O, n = 60). There was no difference in CP between the two ICUs (mean CP was 43 and 48 cmH₂O respectively). There were three (5%) CPs above 100 cmH₂O. Eight patients had appropriately high CPs (mean CP 52 cmH₂O) as reducing the CP caused an audible air leak to occur.

Conclusion

Over-inflation was more frequent than under-inflation and pressures far exceeding the capillary perfusion and even exceeding the systolic arterial pressure were recorded. We recommend that formal protocols of cuff pressure measurement should be implemented or constant pressure cuff inflators used, especially in those who are undergoing prolonged intubation.