A new prototype of an electronic jet-ventilator and its humidification system

Background:
Adequate humidification in long-term jet ventilation is a critical
aspect in terms of clinical safety.

      Aim:
      To assess a prototype of an electronic jet-ventilator and its
            humidification system.


      Methods:
      Forty patients with respiratory insufficiency were randomly
            allocated to one of four groups. The criterion for inclusion in this study was
            respiratory insufficiency exhibiting a Murray score above 2. The four groups of
            patients were ventilated with three different respirators and four different
            humidification systems. Patients in groups A and B received superimposed
            high-frequency jet ventilation (SHFJV) by an electronic jet-ventilator either
            with (group A) or without (group B) an additional humidification system.
            Patients in group C received high-frequency percussive ventilation (HFPV) by a
            pneumatic high-frequency respirator, using a hot water humidifier for warming
            and moistening the inspiration gas. Patients in group D received conventional
            mechanical ventilation using a standard intensive care unit respirator with a
            standard humidification system. SHFJV and HFPV were used for a period of 100 h
            (4days).


      Results:
      A significantly low inspiration gas temperature was noted in
            patients in group B, initially (27.2 ± 2.5°C) and after 2 days
            (28.0 ± 1.6°C) (P < 0.05). The percentage of relative
            humidity of the inspiration gas in patients in group B was also initially
            significantly low (69.8 ± 4.1%; P < 0.05) but rose to an average
            of 98 ± 2.8% after 2 h. The average percentage across all four groups
            amounted to 98 ± 0.4% after 2 h. Inflammation of the tracheal mucosa was
            found in patients in group B and the mucosal injury score (MIS) was
            significantly higher than in all the other groups. Patients in groups A, C and
            D showed no severe evidence of airway damage, exhibiting adequate values of
            relative humidity and temperature of the inspired gas.


      Conclusion:
      The problems of humidification associated with jet ventilation can
            be fully prevented by using this new jet-ventilator. These data were sustained
            by nondeteriorating MIS values at the end of the 4-day study period in groups
            A, C and D.