Humidification on Ventilated Patients: Heated Humidifications or Heat and Moisture Exchangers?

Area of Science:

• Respiratory Physiology
• Critical Care Medicine

Background:

• Artificial airways and mechanical ventilation bypass the upper airway's natural air conditioning functions.
• This bypass impairs the filtration, humidification, and warming of inspired gases.
• Noninvasive ventilation may also have suboptimal humidification due to high airflow and leakage compensation.

Purpose of the Study:

• To highlight the physiological consequences of altered inspired gas conditioning in patients requiring artificial airways and mechanical ventilation.
• To discuss the limitations of current ventilation strategies in maintaining optimal airway conditions.
• To introduce the role of external humidification, heating, and filtration devices.

Main Methods:

• Review of physiological principles governing airway conditioning.
• Analysis of the impact of endotracheal tubes and noninvasive ventilation on inspired air.
• Discussion of compensatory mechanisms in the tracheobronchial tree.
• Overview of external humidification and heating devices.

Main Results:

• Artificial airways eliminate natural air filtration, humidification, and warming.
• High airflow in noninvasive ventilation can lead to inadequate humidification.
• The tracheobronchial tree's limited capacity to compensate for moisture and heat deficits.
• Impaired mucociliary function, altered secretions, and compromised gas exchange homeostasis.

Conclusions:

• Altered inspired gas conditioning is a significant issue in patients with artificial airways and mechanical ventilation.
• External devices are developed to address deficits in humidification, heating, and filtration.
• Further evidence is needed to fully support the use of these external devices.