Chest
Volume 115, Issue 6, June 1999, Pages 1646-1652
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Clinical Investigations in Critical Care
Bedside Evaluation of Efficient Airway Humidification During Mechanical Ventilation of the Critically Ill

https://doi.org/10.1378/chest.115.6.1646Get rights and content

Study objective

To determine the correlation between simple rating of condensation seen in the flex-tube connecting the heating and humidifying device used with the endotracheal tube and hygrometric parameters (absolute and relative humidity and tracheal temperature) measured by psychrometry.

Design

Prospective randomized clinical trial.

Setting

Medical ICU of Louis Mourier Hospital, Colombes, France, a university-affiliated teaching hospital.

Patients

Forty-five consecutive mechanically ventilated critically ill patients.

Interventions

Patients undergoing mechanical ventilation were randomly assigned to receive humidification with one of the four heat and moisture exchangers (HMEs) tested or with a conventional heated humidifier.

Measurements

The hygrometric performances of four HMEs (BB2215, BB50, and BB100 from Pall Biomedical, Saint-Germaine-en-Laye, France; and Hygrobac-Dar from Mallinckrodt, Mirandola, Italy) and a heated humidifier (Fisher & Paykel; Auckland, New Zealand) were studied after 3 h and also after 48 h of use for the Hygrobac-Dar and correlated to a clinical visual inspection rating the amount of condensation in the flex-tube of the endotracheal tube.

Results

A total of 95 measurements in 45 patients were performed. The best hygrometric parameters were obtained with the heated humidifier (p < 0.001). The Hygrobac-Dar yielded significantly higher values for both humidities and tracheal temperature than the other three HMEs (p < 0.001). The performance of Hygrobac-Dar was unchanged after 48 h of use. There was a significant correlation between the condensation seen in the flex-tube and the hygrometric parameters measured by psychrometry (absolute humidity, rho = 0.7; relative humidity, rho = 0.7; tracheal temperature, rho = 0.5, p < 0.0001).

Conclusion

In mechanically ventilated ICU patients, visual evaluation of the condensation in the flex-tube provides an estimation of the heating and humidifying efficacy of the heating and humidifying device used, thus allowing the clinician bedside monitoring of airway humidification.

Section snippets

Patients

All consecutive mechanically ventilated patients were eligible for inclusion in the study. Patients were randomly allocated to ventilation using one of five humidification devices (see below) for a 3-h period, after which they were ventilated with the device normally used in our unit, the Hygrobac-Dar (HD) (Mallinckrodt Medical S.p.A.; Mirandola, Italy). Indications for mechanical ventilation according to Zwillich and coworkers19 were recorded along with the Simplified Acute Physiology Score

Results

A total of 87 clinical measurements and 95 psychrometric measurements were performed on 45 patients. There were 20 measurements for each HME and 15 measurements for the HH. There were no differences between the patients allocated to each of the devices in terms of age, SAPS,20 minute ventilation, tidal volume, or indications for mechanical ventilation19(Table 1).

Discussion

This study shows that simple visual inspection of the amount of moisture in the flex-tube connecting the HME to the endotracheal tube (or the Y-piece to the endotracheal tube when using a HH) provides an accurate estimation of the humidifying performances of the heating and humidifying device used (ie, HME or HH). These findings may be important since recommendations for the use of HMEs in the ICU lack evidence-based guidelines partly because of the few data available on assessment of HME

References (35)

  • T Sottiaux et al.

    Comparative evaluation of three heat and moisture exchangers during short-term postoperative mechanical ventilation

    Chest

    (1993)
  • TE Oh et al.

    Resistance of humidifiers, and inspiratory work imposed by a ventilator-humidifier circuit

    Br J Anaesth

    (1991)
  • J Chalon et al.

    Humidity and the anesthetized patient

    Anesthesiology

    (1979)
  • I Cohen et al.

    Endotracheal tube occlusions associated with the use of heat and moisture exchangers in the intensive care unit

    Crit Care Med

    (1988)
  • J Roustan et al.

    Comparison of hydrophobic heat and moisture exchangers with heated humidifiers during prolonged mechanical ventilation

    Intensive Care Med

    (1992)
  • M Villafane et al.

    Gradual reduction of endotracheal tube diameter during mechanical ventilation via different humidification devices

    Anesthesiology

    (1996)
  • A Tenaillon et al.

    Filtre échangeurs de chaleur et d'humidité versus humidificateurs chauffant en ventilation mécanique

    Réan Soins Intens Méd Urg

    (1989)
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    The authors did not receive any financial support from and do not haveany commitment with any of the brands of the humidifying devices testedin this study.

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