The use of humidification system to reduce the work of breathing in mechanical ventilated patients

Abstract

Critically ill patients in an intensive care unit (ICU) often require mechanical ventilation (MV). Humidification systems are essential devices for MV which replace the natural heat and moisture exchange process of inspired gases. A heat and moisture exchanger (HME) is commonly used for the humidification of MV patients in ICU. In contrast, a heated humidifier (HH) that is a more complicated device is used only for prolonged MV patients because of its higher cost and nurse workload. However, HME may increase the breathing workload of patients, thereby inflicting damage to their respiratory function, especially among respiratory failure patients. However, there was no evidence-based guideline that instructs nurses on choosing humidification devices in ICU.

This dissertation aimed to 1) evaluate the current evidence and formulate evidence-based guideline in selecting a humidification device for mechanically ventilated acute respiratory distress syndrome (ARDS) patients in reducing the risks of breathing workload; 2) assess its implementation potential, as well as its feasibility and transferability; and 3) develop implementation strategies and evaluation plans for the use of this device in an adult ICU.

Three electronic databases, namely, Proquest, Ovid, and Google Scholar, were searched for randomized controlled trials (RCTs) of humidification systems for MV. Eight articles were retrieved. Their reference lists were read and found two additional RCT. Four high-quality RCT showed that HH increased the breathing workload more than HME. Several studies showed that HME has potential drawbacks of significantly increase airway resistance, minute ventilation, CO2 retention, and respiratory discomfort. However, studies showed that no significant difference of ventilator-associated pneumonia (VAP) rate between HME and HH. The initial application of HME is safer and less costlyl. However, prolonged use of HME in ARDS patients may induce further workload on the respiratory system and worsen treatment progress.

An evidence-based clinical guideline in choosing the humidification system was formulated and assessed using the appraisal instruments of Scottish Intercollegiate Guideline Network. It is deemed to be transferable with patient characteristics, clinical situation, and organizational infrastructure similar to studies evaluated the suggested innovation. Feasibility was also assessed and is considered to be high. The setup and running cost per year were HKD17450 and HKD6600. Although the humidification system had no actual cost reduction, non-material benefits such as prevention of tube blockage, reduction in breathing workload, and respiratory discomfort were more important than the cost.

An implementation plan including a one-month communication plan with stakeholders and one-month pilot testing were developed. The evaluation of the guideline will last for 10 months. The effectiveness of the innovation will be determined by the reduction in breathing workload, cost and benefit ratio, and staff satisfaction level.