PEEP has beneficial effects on inflammation in the injured and no deleterious effects on the noninjured lung after unilateral lung acid instillation

• Published in: Intensive care medicine 2006-05, Vol.32 (5), p.740-749
• Main Authors: SCHREIBER, Torsten, HUETER, Lars, GASER, Elke, SCHMIDT, Barbara, SCHWARZKOPF, Konrad, REK, Helga, KARZAI, Waheedullah
• Format: Article
• Language: English
• Subjects: Acute respiratory distress syndrome; Administration, Inhalation; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Artificial respiration; Biological and medical sciences; Blood. Blood coagulation. Reticuloendothelial system; Care and treatment; Causes of; Chronic obstructive pulmonary disease, asthma; Complications and side effects; Cytokines; Cytokines - analysis; Diagnosis; Dosage and administration; Hydrochloric acid; Hydrochloric Acid - administration & dosage; Hydrochloric Acid - adverse effects; Inflammation; Intensive care; Intensive care medicine; Intensive Care Units; Lavage; Male; Medical sciences; Pharmacology. Drug treatments; Pneumology; Pneumonia - diagnosis; Pneumonia - immunology; Positive-Pressure Respiration; Radiography; Random Allocation; Rats; Rats, Wistar; Respiration, Artificial - adverse effects; Respiratory Distress Syndrome, Adult - diagnostic imaging; Respiratory Distress Syndrome, Adult - pathology; Ventilators
• ISSN: 0342-4642; 1432-1238
• DOI: 10.1007/s00134-006-0117-6

In clinical lung injury areas of inflammation and structural alveolar alteration are unevenly distributed and interspaced between healthy or less injured lung areas. Positive end-expiratory pressure (PEEP) applied with mechanical ventilation (MV) may affect injured and healthy lung areas differently. We compared the effects of PEEP on the inflammatory response in injured and noninjured regions of the lung in an animal model of unilateral lung acid instillation. Anesthetized, paralyzed, and ventilated rats. Rats underwent left-endobronchial instillation with either hydrochloric acid or isotonic saline and were randomized 24 h later to MV using constant tidal volume (16 ml/kg) with either ZEEP, PEEP at 5 mmHg, or PEEP at 10 mmHg. After 4 h of MV the animals (n=9 or 10 per group) were killed and inflammatory markers assessed in left- and right-lung lavage fluid samples. In four additional animals per group differential lung perfusion was assessed. Unilateral acid injury alone worsened oxygenation, decreased left-lung perfusion, and increased left-lung lavage neutrophil and macrophage counts and cytokine levels. MV with ZEEP further impaired oxygenation and further decreased left-lung perfusion in acid-injured animals. MV with high PEEP preserved oxygenation and significantly decreased left-lung lavage protein content and cell counts in acid-injured animals and had no deleterious effect on the right (noninjured) lung. In this model of unilateral lung acid injury high PEEP attenuates the inflammatory cell response in the acid-injured lung, preserved oxygenation and has no deleterious effects in the opposite lung.