Do lower cuff pressures reduce damage to the tracheal mucosa? A scanning electron microscopy study in neonatal pigs.

Background Modern high volumelow pressure (HVLP) endotracheal tubes (ETT) cuffs can seal the trachea using baseline cuff pressures (CP) lower than peak inspiratory airway pressures (PIP). The aim of the study was to determine whether this technique reduces the damage to the tracheal mucosa compared to constant CP of 20 cmH2O. Methods Eighteen piglets were intubated with an ID 4.0 mm HVLP cuffed ETT (Microcuff PET) and artificially ventilated with 20 cmH2O PIP and 5 cmH2O PEEP. Animals were randomly allocated to two groups of CP: group A (just seal; n = 9) and group B (20 cmH2O; n = 9), controlled constantly with a manometer during the following 4-h study period under sevoflurane anesthesia. After euthanasia, cuff position was marked in situ. Damage in the cuff region was evaluated with scanning electron microscopy (SEM) examination by grading of mucosal damage and by estimating percentage of intact mucosal area both by a blinded observer. Results Maximal CP to seal the trachea in group A ranged from 12 to 18 cmH2O (median: 14 cmH2O). Using a mixed effects model approach, the estimated mean effect of group B vs group A was an increase of 17.9% (SE 8.1%) higher proportion of pictures with an area of at least 5% intact mucosa (P = 0.042). Conclusion Minimal sealing pressures with cyclic pressure changes from CP did not result in decreased damage to the tracheal mucosa compared to constant CP of 20 cmH2O in this short-term animal trial.