THE EFFECTS OF CUFFED ENDOTRACHEAL TUBES ON THE

Direct tracheoscopy was employed to assess tracheal damage following prolonged intubation. Comparison of conventional and low-pressure cuffs showed that there was less trauma from the low-pressure cuff. Comparison of tube sizes showed a reduction in injury with 8-mm diameter tubes compared with larger ones. Knowledge of tracheal damage following prolonged endotracheal intubation has depended hitherto upon analysis of retrospective evidence, postmortem specimens and animal experimentation. The oppor-tunity was taken to compare the effects of standard cuffed Portex Blue-line tubes with those of low-pressure (floppy) cuffs using a fibreoptic laryngo-scope. The tubes were all made of the same material and had been sterilized with ethylene oxide by the manufacturers. The object of the present study was to utilize a technique which would enable the observer to visualize the tracheal mucosa at the time of extuba-tion. The patients in this series were undergoing cardiopulmonary bypass surgery, and were ventila-ted (IPPV) for an average of 15 hours. All patients returned to the intensive care unit after operation, accurate records of their cardiovascular state and drug administration being available for retrospective analysis. METHOD Forty patients were allocated randomly to two groups (table I). The control group was intubated with conventional Portex Blue-line tubes and the test group with Portex Blue-line low-pressure cuffed tubes which were available for test purposes. These tubes are now commercially available and they possess cuffs identical to the present "floppy" Portex endotracheal and tracheostomy tubes. At the onset of the study we were restricted to the use of 8-mm low-pressure cuffed tubes. At a later stage 9-mm low-pressure cuffed tubes became available and tubes larger than 8 mm were used in both groups. After operation patients were ventilated artifi-cially using Cape ventilators, the duration of intuba