Comparison of three different humidification systems during prolonged mechanical ventilation.

BACKGROUND

An efficient humidification system is expected to maintain fluid and easily drainable airway secretions. This study aims to compare the efficiency and safety of three humidification systems during prolonged mechanical ventilation.

DESIGN

Two-center, prospective, randomized study.

METHODS

45 critically ill patients undergoing mechanical ventilation were included in the study and allocated to receive one of three humidification techniques: 1) Bennett Cascade water-bath humidifier (Bennett group); 2) Fisher & Paykel servocontrolled humidifier (F & P group); 3) HME Hygrobac DAR (HME group). Clinical and experimental observations were conducted for 3 to 7 consecutive days and included: body T degree, room T degree, inspired gas T degree, tracheal T degree, relative and absolute humidity, heat and water loss, airway secretion score, need for endotracheal saline instillation and incidence of ETT occlusion.

RESULTS

The HME group showed a lower temperature of inspired gases compared to the F & P group (p < 0.05); it also showed a lower absolute humidity compared to both Bennett and F & P groups (p < 0.05). A better airway secretion score was obtained in Bennett and F & P groups compared to the HME group (p < 0.01).

CONCLUSIONS

Passive humidification systems provided low degrees of humidity and temperature and could not maintain good secretions. Active systems appeared to satisfy the recommended standards and to allow fluid and easily drainable secretions.