Application of Tracheal Gas Insufflation to Acute Unilateral Lung Injury in an Experimental Model

Abstract

In unilateral lung injury, application of global positive end-expiratory pressure (PEEP) may cause overdistension of normal alveoli and redistribution of blood flow to diseased lung areas, thereby worsening oxygenation. We hypothesized that selective application of tracheal gas insufflation (TGI) will recruit the injured lung without causing overdistension of the normal lung. In eight anesthetized dogs, left lung saline lavage was performed until Pa(O(2))/FI(O(2)) fell below 100 mm Hg. Then, the dogs were reintubated with a Univent single lumen endotracheal tube that incorporates an internal catheter to provide TGI. After injury, increasing PEEP from 3 to 10 cm H(2)O did not change gas exchange, hemodynamics, or lung compliance. Selective TGI, while keeping end-expiratory lung volume (EELV) constant, improved Pa(O(2))/FI(O(2)) from 212 +/- 43 to 301 +/- 38 mm Hg (p < 0.01) while Pa(CO(2)) and airway pressures decreased (p < 0.01). During selective TGI, reducing tidal volume to 5.2 ml/kg while keeping EELV constant, normalized Pa(CO(2)), did not affect Pa(O(2))/FI(O(2)), and decreased end-inspiratory plateau pressure from 16.6 +/- 1.0 to 11.9 +/- 0.5 cm H(2)O (p < 0.01). In unilateral lung injury, we conclude that selective TGI (1) improves oxygenation at a lower pressure cost as compared with conventional mechanical ventilation, (2) allows reduction in tidal volume without a change in alveolar ventilation, and (3) may be a useful adjunct to limit ventilator-associated lung injury.

Endexpiratory lung volume measurement correlates with the ventilation/perfusion mismatch in lung injured pigs

“…1) but also in patients suffering from ARDS [16] and substantially influence V A /Q mismatch. Conversion of low to normal V A /Q areas may not be fully reflected by EELV increase, which explains that PaO 2 can increase despite constant EELV [17]. This highlights the need for differentiation between mere anatomical and functional recruitment [18].…”

Overview of the Pathology of Three Widely Used Animal Models of Acute Lung Injury

“…300 mm Hg [11,20] . In very rare cases, in order to provide an intraindividual comparison, lung injury is produced only in a unilateral lung [9,25] .…”

Continuous lateral rotation therapy – a review

“…Positioning therapies have been targeted to meet specific lung pathology. The literature demonstrates conclusively that (Blanch et al, 2001) for patients experiencing a consolidated pneumonia in one lung, positioning the patient with the good lung down will result in better oxygenation.…”