Are selective lung recruitment maneuvers hemodynamically safe in severe hypovolemia? An experimental study in hypovolemic pigs with lobar collapse.
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.
Hansen
Lars Kjaersgaard
LK
Department of Anesthesia and Intensive Care, Center for Cardiovascular Research, Aalborg Hospital, Arhus University Hospitals, Aalbo, Denmark. lars.hansen@rn.dk
Koefoed-Nielsen
Jacob
J
Nielsen
Jonas
J
Larsson
Anders
A
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
D010100:Oxygen