How to ventilate lungs as small as 12.5% of normal: the new technique of intratracheal pulmonary ventilation.
We wished to determine in a laboratory animal model how much residual lung was needed to sustain total gas exchange. In a series of young, healthy lambs weighing approximately 10 kg that were sedated and paralyzed, we progressively excluded from gas exchange all the left lung (a total of 43%), plus the right lower and cardiac lobes (81%), plus the right middle lobe (87.5%). In some studies, the respective lobes were surgically removed; in others, the bronchi and the pulmonary arteries to the respective lobes were ligated. We provided pulmonary ventilation using the pressure control mode (Servo 900 C) at a tidal volume of 20 mL/kg multiplied by the fraction of the remaining lungs, a respiratory rate up to 120/min, a peak inspiratory pressure of 12-15 cm H2O, and a positive end-expiratory pressure of 3 cm H2O. Those lambs with at least both the right upper lobe (RUL) and right middle lobe remaining (19% of total lungs) were weaned to room air on mechanical ventilation within 48 h. Ventilating RUL (12.5% of remaining lung) with the same ventilator required a substantially higher tidal volume and peak inspiratory pressure to result in adequate alveolar ventilation but led to respiratory failure and death within 8 h. We then applied a newly developed system of intratracheal pulmonary ventilation to ventilate the RUL (12.5% of remaining lung) alone. A continuous flow of humidified mixture of air and oxygen was directly passed into the trachea at the level of the carina through a diffuser at a tidal volume of 2.5 mL/kg. A single valve controlled expiration and respiratory rate.(ABSTRACT TRUNCATED AT 250 WORDS)
Müller
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Section on Pulmonary and Cardiac Assist Devices, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892.
Kolobow
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Mandava
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Jones
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Vitale
G
G
Aprigliano
M
M
Yamada
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K
D000818:Animals; D005069:Evaluation Studies as Topic; D008168:Lung / Q000033:anatomy & histology* / Q000502:physiology / Q000601:surgery; D008954:Models, Biological; D011013:Pneumonectomy; D011312:Pressure; D011652:Pulmonary Circulation / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012121:Respiration, Artificial / Q000295:instrumentation / Q000379:methods*; D015656:Respiratory Mechanics / Q000502:physiology; D012756:Sheep; D013990:Tidal Volume; D014132:Trachea; D015300:Ventilator Weaning