Abstract
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 degrees C) and after 2 days (28.0 +/- 1.6 degrees 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.
Highlights
High-frequency jet ventilation (HFJV) has proved to be an alternative to conventional mechanical ventilation (CMV) [1,2,3,4]
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
Summary
High-frequency jet ventilation (HFJV) has proved to be an alternative to conventional mechanical ventilation (CMV) [1,2,3,4]. Combined highfrequency jet ventilation (CHFJV) is a technique that requires a conventional respirator (endotracheal tube) and HFJV = high-frequency jet ventilation; CMV = conventional mechanical ventilation; CHFJV = combined high-frequency jet ventilation; SHFJV = superimposed high-frequency jet ventilation; HFPV = high-frequency percussive ventilation; ICU = intensive care unit; ARDS = acute respiratory distress syndrome; ALI = acute lung insufficiency; PCWP = pulmonary capillary wedge pressure; CI = cardiac index; SVRI = systemic vascular resistance index; PEEP = positive end-expiratory pressure; FiO2 = fractional inspiratory oxygen concentration; I:E = inspiration to expiration time ratio; SaO2 = arterial oxygen saturation; MIS = mucosal injury score; QH2O = rate of humidification; ISB = isothermic saturation boundary; LF = low frequency; HF = high frequency; CPPV = continuous positive pressure ventilation; Pmax = maximal airway pressure; PaO2 = partial pressure of oxygen. Adequate humidification in long-term jet ventilation is a critical aspect in terms of clinical safety
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