Influence of the humidification device during acute respiratory distress syndrome

Intensive Care Med. 2003 Dec;29(12):2211-2215. doi: 10.1007/s00134-003-1926-5. Epub 2003 Aug 6.


Objective: To evaluate the effects of the humidification device on respiratory, hemodynamic and gas exchange parameters in acute respiratory distress syndrome (ARDS) patients.

Design: A prospective open study.

Setting: A medical intensive care unit of a university hospital.

Patients: Acute respiratory distress syndrome patients, with hypercapnia (PaCO(2)>60 mmHg).

Intervention: A progressive reduction of the humidification system dead space (DSh). The following five conditions were tested sequentially: (1). heat and moisture exchanger (internal volume=95 ml) with a tracheal closed-suction system (internal volume=25 ml; total DSh=120 ml), (2). heat and moisture exchanger (internal volume=45 ml) with the closed-suction system (DSh=70 ml), (3). heat and moisture exchanger (internal volume=25 ml) with the closed-suction system (DSh=50 ml), (4). heated humidifier with the closed-suction system (DSh=25 ml) and (5). heated humidifier alone (DSh=0 ml). Recordings were performed at baseline and every 30 min after each artificial dead-space reduction. All ventilatory settings remained constant during the measurement periods.

Results: Ten ARDS patients were included. A significant PaCO(2) decrease was observed at each humidification system dead-space reduction, compared to baseline: PaCO(2 )=80.3+/-20 mmHg at DSh(120) compared to PaCO(2 )=63.6+/-13 mmHg at DSh(0) ( p<0.05). No changes were observed for hemodynamic and ventilatory parameters between the different humidification devices.

Conclusion: Artificial airway dead-space reduction allows a significant PaCO(2) reduction. Independently of any respiratory mechanical changes, this very simple maneuver may be of importance when low tidal volume ventilation is used in ARDS patients, and when PaCO(2) lowering is warranted.

Publication types

  • Clinical Trial

MeSH terms

  • Adult
  • Aged
  • Blood Pressure / drug effects
  • Equipment Design
  • Female
  • Heart Rate / drug effects
  • Humans
  • Humidity*
  • Intensive Care Units
  • Male
  • Middle Aged
  • Norepinephrine / therapeutic use
  • Positive-Pressure Respiration
  • Prospective Studies
  • Pulmonary Gas Exchange
  • Respiration, Artificial*
  • Respiratory Distress Syndrome / classification
  • Respiratory Distress Syndrome / mortality
  • Respiratory Distress Syndrome / therapy*
  • Severity of Illness Index
  • Sympathomimetics / therapeutic use


  • Sympathomimetics
  • Norepinephrine