Acute respiratory distress syndrome in two rhesus macaques (Macaca mulatta)

Abstract

Acute respiratory distress syndrome (ARDS) is an important and potentially life-threatening complication in humans that arises subsequent to a variety of primary insults including noxious fume inhalation, infection, and trauma. Here we describe the first two cases of ARDS reported in association with postoperative complications in rhesus macaques. In agreement with the multifactorial nature of the human syndrome, ARDS in one monkey was attributed to sepsis, whereas in the other it was ascribed to neurogenic trauma. Despite the different etiologies, both monkeys demonstrated clinical features of ARDS, including progressive dyspnea and pulmonary edema, and syndrome-defining histopathologic criteria including edema with intraalveolar neutrophils, fibrinohemorrhagic effusions with crescentic membranes, and interstitial vascular degeneration. Recognition and aggressive treatment of ARDS at an early stage may improve survival rates in dyspneic nonhuman primates with underlying extrapulmonary diseases.

Figure 1.

Dorsoventral thoracic radiograph, case 1. Note coalescing pulmonary edema obscuring small airway detail.

Figure 2.

Brain and lung histopathology, case 1. (A) Severe fibrinosuppurative meningitis (arrows) with localized infiltration of polymorphonuclear cells (PMN) into subjacent gray matter (arrowheads). (B) Focally extensive fibrinoproteinaceous transudate and hemorrhage occluding terminal airways; note reactive changes to peripheral alveoli including transalveolar fibrillar bridging, epithelioid macrophages, and type II pneumocyte hypertrophy. (C) Severe interstitial congestion with numerous intravascular PMN and tattered fibrinoid material lining alveolar walls (arrows). (D) Alveolar cellular exudate composed of PMN and erythrocytes (arrow). (E) Crescentic condensation of fibrinoproteinaceous material (arrow) lining airway epithelium, an acute precursor to hyaline membranes. (F) Carstair stain demonstrating organized fibrin (pink; arrow) lining subpleural alveoli. Hematoxylin and eosin stain (A through E), Carstair stain (F); bar: 160 μm (A), 80 μm (B), 40 μm (C through F).