[Analysis on risk factors of endotracheal cuff under inflation in mechanically ventilated patients]

To investigate the prevalent condition of endotracheal cuff pressure and risk factors for under inflation.

A prospective cohort study was conducted. Patients admitted to the Department of Critical Care Medicine of Fuxing Hospital Affiliated to Capital Medical University, who were intubated with a high-volume low-pressure endotracheal tube, and had undergone mechanical ventilation for at least 48 hours, were enrolled. The endotracheal cuff pressure was determined every 8 hours by a manual manometer connected to the distal edge of the valve cuff at 07 : 00, 15 : 00, and 23 : 00. Measurement of the endotracheal cuff pressure was continued until the extubation of endotracheal or tracheostomy tube, or death of the patient. According to the incidence of under inflation of endotracheal cuff, patients were divided into the incidence of under inflation lower than 25% group (lower low cuff pressure group) and higher than 25% group (higher low cuff pressure group). The possible influencing factors were evaluated in the two groups, including body mass index (BMI), size of endotracheal tube, duration of intubation, use of sedative or analgesic, number of leaving from intensive care unit (ICU), the number of turning over the patients, and aspiration of sputum. Logistic regression analysis was used to determine risk factors for under-inflation of the endotracheal cuff.

During the study period, 53 patients were enrolled. There were 812 measurements, and 46.3% of them was abnormal, and 204 times (25.1%) of under inflation of endotracheal cuff were found. There were 24 patients (45.3%) in whom the incidence of under inflation rate was higher than 25%. The average of under inflation was 7 (4, 10) times. Compared with the group with lower rate of low cuff pressure, a longer time for intubation was found in group with higher rate of low cuff pressure [hours: 162 (113, 225) vs. 118 (97, 168), Z=-2.034, P=0.042]. There were no differences between the two groups in other factors, including size of endotracheal tube, the time from intubation to first measurement of endotracheal cuff pressure, number of leaving from ICU during admission, use of sedative agent or analgesic, and the number of body turning and aspiration (all P>0.05). No risk factor was found resulting from under inflation of the endotracheal cuff by logistic regression analysis. No significant difference was found in the incidence of ventilator associated pneumonia, duration of mechanical ventilation, successful rate of weaning on 28th day, or 28-day mortality after weaning from mechanical ventilation, and ICU mortality between the two groups. However, patients in the group of higher rate of low cuff pressure had a longer ICU stay compared with that in the group of lower rate of low cuff pressure group [days: 13 (8, 21) vs. 10 (6, 18), Z=-2.120, P=0.034].

Abnormal endotracheal cuff pressure is common in critically ill patients with intratracheal intubation. Duration of intubation is associated with under inflation of the cuff, and it calls for strengthening monitoring and management.