title: Are selective lung recruitment maneuvers hemodynamically safe in severe hypovolemia? An experimental study in hypovolemic pigs with lobar collapse.
abstract: BACKGROUND
  We have previously shown, in normovolemic pigs, that a selective lung recruitment maneuver (S-LRM), i.e., insufflation of air-oxygen via a balloon catheter with its tip located in the bronchus of a collapsed lung lobe, effectively improves oxygenation and lung volume without affecting hemodynamics negatively. In this study, we examined the respiratory and circulatory effects of S-LRM during hypovolemia with compromised circulation.
  
  
  METHODS
  In eight ventilated (fraction of inspired oxygen, Fio2 1.0) and anesthetized pigs a balloon catheter was inserted in the bronchus of the right lower lung lobe. The lobe was selectively lavaged to create a dense lobar collapse. The pigs were then subjected to S-LRM (40 cm H2O airway pressure for 30 s) at normovolemia, after venesection of 20% and 40% of the blood volume, respectively. Blood gases, compliance of the respiratory system (Crs), vascular pressures, and cardiac output were registered before, during, and after the S-LRM.
  
  
  RESULTS
  Pao2, venous admixture, and Crs improved significantly with S-LRM at all three volume levels. No change in hemodynamics with S-LRM occurred in normovolemia and 20% hypovolemia. For 40% hypovolemia, cardiac output was unchanged by S-LRM, whereas minor decreases in mean arterial blood pressure were seen: 48 (37-52) mm Hg (median, 25th and 75th percentiles) 3 min before S-LRM, 40 (35-44) mm Hg at the end of S-LRM (P = 0.0207), and 47 (39-54) mm Hg 3 min after S-LRM.
  
  
  CONCLUSIONS
  A S-LRM effectively improved oxygenation and Crs and had only minor circulatory side effects, even in severe hypovolemia in this animal model of lobar collapse.
authors: Department of Anesthesia and Intensive Care, Center for Cardiovascular Research, Aalborg Hospital, Arhus University Hospitals, Aalbo, Denmark. lars.hansen@rn.dk
authors: Lars Kjaersgaard
authors: LK
authors: Hansen
authors: Jacob
authors: J
authors: Koefoed-Nielsen
authors: Jonas
authors: J
authors: Nielsen
authors: Anders
authors: A
authors: Larsson
mesh_terms: D000403:Airway Resistance; D000818:Animals; D001794:Blood Pressure; D002302:Cardiac Output; D002404:Catheterization / Q000009:adverse effects; D002496:Central Venous Pressure; D004195:Disease Models, Animal; D006339:Heart Rate; D020896:Hypovolemia / Q000097:blood / Q000150:complications* / Q000503:physiopathology / Q000628:therapy; D007327:Insufflation / Q000009:adverse effects / Q000379:methods*; D008170:Lung Compliance; D010100:Oxygen / Q000008:administration & dosage* / Q000097:blood; D011651:Pulmonary Artery / Q000503:physiopathology; D001261:Pulmonary Atelectasis / Q000097:blood / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D015656:Respiratory Mechanics; D012720:Severity of Illness Index; D013552:Swine
chemical_list: D010100:Oxygen