Performance evaluation of three vaporizing humidifiers and two heat and moisture exchangers in patients with minute ventilation > 10L/min

Polytech Marseille, Marsiglia, Provence-Alpes-Côte d'Azur, France
Chest (Impact Factor: 7.48). 11/1992; 102(5):1347-50. DOI: 10.1378/chest.102.5.1347
Source: PubMed


To compare the thermal and humidification capacity of three heated hot water systems (HHWSs) and two heat and moisture exchangers (HMEs) in ICU patients submitted to minute ventilation > 10 L/min.
Prospective, controlled, randomized, not blinded study.
ICU of a university hospital.
ICU patients requiring controlled mechanical ventilation with minute ventilation > 10 L/min. Patients had to be sedated and paralyzed and had to require ventilation for more than four days.
Following a randomized order, the patients were ventilated for 24-h periods with three HHWSs (Bennett Cascade 2 humidifier, Fisher-Paykel MR 460 and MR 600) and two HMEs (Pall Ultipor and Hygrobac filter).
In each patient and for each 24-h period, absolute humidity, (AH), relative humidity (RH) of inspired gases, and tracheal temperature were obtained. Two HHWSs (Bennett and Fisher-Paykel MR 460) had a better thermal and humidification capacity than any other systems (p < 0.001). The hydrophobic HME (Pall filter) had a poor thermal and humidification capacity (RH: 79 +/- 8.7 percent; AH: 20.6 +/- 2.3 mg H2O/L). The hygroscopic filter (Hygrobac filter) had better thermal and humidification capacity than the Pall filter (RH: 92.5 +/- 3.6 percent; AH: 29.1 +/- 1.8 mg H2O/L; p < 0.001). Tracheal temperature was well preserved by all systems. The thermic and humidification capability of the Hygrobac filter declined over 24 h. Since the Pall filter could not achieve an AH > 25 mg H2O/L in any patient, it was not studied beyond the first measurement.
The Hygrobac filter had a thermal and humidification capability closed to the two HHWSs (81 to 97 percent) but the capability declines over 24 h. The Pall filter had a poor capability (54 to 74 percent of that of HHWSs).

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    • "(2) the finding that increased respiratory rates resulted in a trend to higher AH that reached significance in 3 of the tested humidifiers is interesting. Previous studies of HMEs in adults and children have found lower AH associated with higher tidal volumes [4] [5] and minute volumes (MVs) [1] [6] [7]. It would seem more logical that an increasing respiratory rate presumably would result in a higher MV, with resultant lower AH, but Chikata et al. found the opposite. "

    Full-text · Article · Aug 2012 · Critical care research and practice
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    • "In normal conditions the temperature of expired gases ranges between 28 and 32°C with an AH of 27–33 mgH2O/l [22,23], and thus a temperature of 29–33°C with an AH of 28–35 mgH2O/l should be adequate for inspired gases [2]. Two previous studies [12,13] showed that a HME that is able to deliver a mean AH of 30 mgH2O/l could safely be used for up to 7 days in mechanically ventilated patients. "
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    ABSTRACT: In order to improve the efficiency of heat moisture exchangers (HMEs), new hybrid humidifiers (active HMEs) that add water and heat to HMEs have been developed. In this study we evaluated the efficiency, both in vitro and in vivo, of a new active HME (the Performer; StarMed, Mirandola, Italy) as compared with that of existing HMEs (Hygroster and Hygrobac; Mallinckrodt, Mirandola, Italy). We tested the efficiency by measuring the temperature and absolute humidity (AH) in vitro using a test lung ventilated at three levels of minute ventilation (5, 10 and 15 l/min) and at two tidal volumes (0.5 and 1 l), and in vivo in 42 patients with acute lung injury (arterial oxygen tension/fractional inspired oxygen ratio 283 +/- 72 mmHg). We also evaluated the efficiency in vivo after 12 hours. In vitro, passive Performer and Hygrobac had higher airway temperature and AH (29.2 +/- 0.7 degrees C and 29.2 +/- 0.5 degrees C, [P < 0.05]; AH: 28.9 +/- 1.6 mgH2O/l and 28.1 +/- 0.8 mgH2O/l, [P < 0.05]) than did Hygroster (airway temperature: 28.1 +/- 0.3 degrees C [P < 0.05]; AH: 27 +/- 1.2 mgH2O/l [P < 0.05]). Both devices suffered a loss of efficiency at the highest minute ventilation and tidal volume, and at the lowest minute ventilation. Active Performer had higher airway temperature and AH (31.9 +/- 0.3 degrees C and 34.3 +/- 0.6 mgH2O/l; [P < 0.05]) than did Hygrobac and Hygroster, and was not influenced by minute ventilation or tidal volume. In vivo, the efficiency of passive Performer was similar to that of Hygrobac but better than Hygroster, whereas Active Performer was better than both. The active Performer exhibited good efficiency when used for up to 12 hours in vivo. This study showed that active Performer may provide adequate conditioning of inspired gases, both as a passive and as an active device.
    Full-text · Article · Oct 2004 · Critical care (London, England)
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    • "The introduction of light, disposable devices that effectively conserve heat and moisture of inspired gases could be a solution to both the problem of humidification and that of heat preservation [9,10,11,12,13,14,15,16,17,18,19]. HMEs preserve patients' heat and water, and overall recover 70% of expired heat and humidity [10,11]. "
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    ABSTRACT: Background: Minimizing total respiratory heat loss is an important goal during mechanical ventilation. The aim of the present study was to evaluate whether changes in tracheal temperature (a clinical parameter that is easy to measure) are reliable indices of total respiratory heat loss in mechanically ventilated patients. Method: Total respiratory heat loss was measured, with three different methods of inspired gas conditioning, in 10 sedated patients. The study was randomized and of a crossover design. Each patient was ventilated for three consecutive 24-h periods with a heated humidifier (HH), a hydrophobic heat-moisture exchanger (HME) and a hygroscopic HME. Total respiratory heat loss and tracheal temperature were simultaneously obtained in each patient. Measurements were obtained during each 24-h study period after 45 min, and 6 and 24 h. Results: Total respiratory heat loss varied from 51 to 52 cal/min with the HH, from 100 to 108 cal/min with the hydrophobic HME, and from 92 to 102 cal/min with the hygroscopic HME (P < 0.01). Simultaneous measurements of maximal tracheal temperatures revealed no significant differences between the HH (35.7-35.9°C) and either HME (hydrophobic 35.3-35.4°C, hygroscopic 36.2-36.3°C). Conclusion: In intensive care unit (ICU) mechanically ventilated patients, total respiratory heat loss was twice as much with either hydrophobic or hydroscopic HME than with the HH. This suggests that a much greater amount of heat was extracted from the respiratory tract by the HMEs than by the HH. Tracheal temperature, although simple to measure in ICU patients, does not appear to be a reliable estimate of total respiratory heat loss.
    Full-text · Article · Feb 2001 · Critical Care
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