Neonatal high-frequency jet ventilation: four years' experience.

During a 4-year period, 34 neonates were treated with high-frequency jet ventilation (HFJV) using two different HFJV systems. Twenty-three of the neonates had severe pulmonary air leaks, five had congenital left-sided diaphragmatic hernias, and six had end-stage respiratory failure without pulmonary air leaks. The two HFJV systems performed similarly in all pathologic conditions. Following HFJV, arterial blood gas values improved in 28 of the 34 patients (82%). Eleven patients (32%) ultimately survived. Of 23 patients with pulmonary air leaks, 17 (74%) improved, nine (39%) survived. One infant with diaphragmatic hernia and one with end-stage respiratory failure survived. Ten of 12 patients (85%) who died following eight or more hours of HFJV had significant tracheal histopathology in the region of the endotracheal tube tip. The lesions ranged from moderate erythema to severe necrotizing tracheobronchitis with total tracheal obstruction. HFJV can be useful in the treatment of severe pulmonary air leaks in neonates and may prove useful in the treatment of congenital diaphragmatic hernias. However, HFJV produces inflammatory injuries in the proximal trachea. More clinical and laboratory studies are needed to define the relative risks and benefits of this new therapy.

High-frequency ventilation and tracheal injuries.

Recent reports linking serious tracheal injuries to various forms of high-frequency ventilation prompted this study. We compared the tracheal histopathology seen following standard-frequency, conventional mechanical ventilation with that seen following high-frequency, conventional mechanical ventilation, and two different forms of high-frequency jet ventilation. Twenty-six adult cats were examined. Each was mechanically ventilated for 16 hours. Seven received standard-frequency, conventional mechanical ventilation at 20 breaths per minute. Seven received high-frequency, conventional mechanical ventilation at 150 breaths per minute. Six received high-frequency jet ventilation at 250 breaths per minute via the Instrument Development Corporation VS600 jet ventilator (IDC). Six received high-frequency jet ventilation at 400 breaths per minute via the Bunnell Life Pulse jet ventilator (BLP). A semiquantitative histopathologic scoring system graded tracheal tissue changes. All forms of high-frequency ventilation produced significant inflammation (erosion, necrosis, and polymorphonuclear leukocyte infiltration) in the trachea in the region of the endotracheal tube tip. Conventional mechanical ventilation produced less histopathology than any form of high-frequency ventilation. Of all of the ventilators examined, the BLP, the ventilator operating at the fastest rate, produced the greatest loss of surface cilia and depletion of intracellular mucus. IDC high-frequency jet ventilation and high-frequency, conventional mechanical ventilation produced nearly identical histologic injuries. In this study, significant tracheal damage occurred with all forms of high-frequency ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Neonatal transcutaneous arterial oxygen saturation monitoring.

Transcutaneous arterial oxygen saturation (TcSaO2) and directly measured oxygen saturation values from 25 neonates with a variety of respiratory problems were compared. At arterial oxygen saturations above 60 per cent, TcSaO2 measurements were accurate and reliable. However, SaO2 values less than 60 per cent were significantly overestimated by TcSaO2, so careful laboratory confirmation of low SaO2 values is necessary. The use, accuracy, and limitations of this noninvasive transcutaneous technique for measuring arterial hemoglobin-oxygen saturation are discussed.

Necrotizing tracheobronchitis: a complication of high-frequency ventilation.

The tracheobronchial histopathologic findings in eight neonates who died after treatment with high-frequency jet ventilation (HFJV) were compared with those in eight similar infants who died after treatment with conventional mechanical ventilation. The HFJV and conventionally treated groups were matched as closely as possible for birth weight, gestational age, and duration of mechanical ventilation. A 4-point, nine-variable histologic scoring system was used to grade tissue changes in the trachea, carina, and mainstem bronchi. The patients who received HFJV had significantly more histologic damage in their tracheas, carinas, and right and left mainstem bronchi. At all levels of the airway examined, HFJV was associated with more inflammation, greater losses of ciliated epithelium, and more mucus within the lumen of the airway than was conventional mechanical ventilation.

Acute airway injury during high-frequency jet ventilation and high-frequency oscillatory ventilation.

BACKGROUND AND METHODS: We compared tracheal histologic injury patterns, airway pressure (Paw) requirements, and in vivo and in vitro estimate of airway humidification in 13 adult cats with normal lungs mechanically ventilated for 16 hr. Six animals were treated with high-frequency jet ventilation at 400 breaths/min and seven animals with high-frequency oscillatory ventilation at 900 breaths/min. RESULTS: Peak airway pressure, Paw, mean Paw, and end-expiratory pressure requirements were significantly higher for high-frequency oscillatory ventilation as compared with high-frequency jet ventilation for similar gas exchange (p less than .01). While in vivo estimates of airway humidification suggested progressively greater H2O delivery into the respirator circuit, and therefore the airway, with higher frequencies, the in vitro study suggested similar relative humidities of the delivered gases during both types of mechanical ventilation. Tracheal injury, measured using a semiquantitative scoring system, was scored similarly for both ventilators studied despite the higher pressure requirements seen with the high-frequency oscillator. CONCLUSIONS: In this animal model, high-frequency ventilation using either jet or oscillation techniques produced similar inflammatory tracheal damage despite differences in Paw exposure and humidity.