Moderate hypercapnia exerts beneficial effects on splanchnic energy metabolism during endotoxemia.
OBJECTIVE
Low tidal volume ventilation and permissive hypercapnia are required in patients with sepsis complicated by ARDS. The effects of hypercapnia on tissue oxidative metabolism in this setting are unknown. We therefore determined the effects of moderate hypercapnia on markers of systemic and splanchnic oxidative metabolism in an animal model of endotoxemia.


METHODS
Anesthetized rats maintained at a PaCO(2) of 30, 40 or 60 mmHg were challenged with endotoxin. A control group (PaCO(2) 40 mmHg) received isotonic saline. Hemodynamic variables, arterial lactate, pyruvate, and ketone bodies were measured at baseline and after 4 h. Tissue adenosine triphosphate (ATP) and lactate were measured in the small intestine and the liver after 4 h.


RESULTS
Endotoxin resulted in low cardiac output, increased lactate/pyruvate ratio and decreased ketone body ratio. These changes were not influenced by hypercapnia, but were more severe with hypocapnia. In the liver, ATP decreased and lactate increased independently from PaCO(2) after endotoxin. In contrast, the drop of ATP and the rise in lactate triggered by endotoxin in the intestine were prevented by hypercapnia.


CONCLUSIONS
During endotoxemia in rats, moderate hypercapnia prevents the deterioration of tissue energetics in the intestine.
Gnaegi
Alex
A
Division of Clinical Pathophysiology and Medical Teaching, Faculty of Biology and Medicine, University Hospital Center, CHUV-BH 08-621, 1011, Lausanne, Switzerland.
Feihl
François
F
Boulat
Olivier
O
Waeber
Bernard
B
Liaudet
Lucas
L
D000818:Animals; D002245:Carbon Dioxide / Q000008:administration & dosage / Q000502:physiology; D019446:Endotoxemia / Q000503:physiopathology*; D004734:Energy Metabolism / Q000187:drug effects* / Q000502:physiology; D006935:Hypercapnia / Q000378:metabolism*; D010101:Oxygen Consumption; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012121:Respiration, Artificial; D012128:Respiratory Distress Syndrome / Q000503:physiopathology / Q000628:therapy; D018805:Sepsis / Q000503:physiopathology; D013152:Splanchnic Circulation / Q000187:drug effects* / Q000502:physiology
D002245:Carbon Dioxide