Respiratory mechanics and morphometry after progressive intraperitoneal effusion

• Published in: Respiration physiology 1995-12, Vol.102 (2), p.217-224
• Main Authors: Augusto, Valéria Maria, de Sousa, Andréa Silvestre, Moll, Renata Junqueira, Duarte, João Gustavo Celani, Zin, Walter Araújo
• Format: Article
• Language: English
• Subjects: Abdomen; Airway Resistance - physiology; Animals; Elastance, static lung; Infusions, Parenteral; Lung - physiology; Mammals, rat; Mechanics of breathing, intraperitoneal effusion; Peritoneal Cavity - physiology; Pulmonary Ventilation - physiology; Rats; Rats, Wistar; Resistance, respiratory system; Respiration - physiology; Respiratory Mechanics - physiology; Thorax
• ISSN: 0034-5687
• DOI: 10.1016/0034-5687(95)00054-2

Respiratory mechanics and thoraco-abdominal morphometry were evaluated in anesthetized, paralyzed, mechanically ventilated rats before and after controlled intraperitoneal injection of warm (37°C) saline. Respiratory system resistances and static elastance were determined in 9 animals using the end inflation occlusion method. Chest wall configuration at both functional residual capacity (FRC) and end inspiration (FRC + Vt) was evaluated in: (a) 6 rats by measurements of lateral and anteroposterior diameters, and circumferences at four levels: 3rd intercostal space, xiphoid, subcostal plane and crista iliaca; and (b) 8 rats by measurements of thoracic cephalo-caudal diameter. In addition, FRC changes were measured in 6 rats. Resistances were not altered but static elastance increased progressively. Morphometric changes were similar at both FRC and FRC + Vt: cephalo-caudal diameter diminished whereas all other diameters augmented; FRC decreased. In conclusion, intraperitoneal infusion of saline in rats augments elastance, and this is related to a cephalad deviation of the diaphragm plus an increase of the circumferences and diameters of the lower thorax.