Small intestine intramucosal PCO(2) and microvascular blood flow during hypoxic and ischemic hypoxia.
OBJECTIVE
To determine whether small intestine intramucosal PCO(2) and mucosal blood flow changes would be different between ischemic and hypoxic hypoxia.


METHODS
Randomized animal experiment.


METHODS
Research laboratory.


METHODS
Anesthetized, mechanically ventilated, and surgically instrumented pigs.


METHODS
Systemic oxygen delivery was lowered in a stepwise manner to decrease it beyond critical oxygen delivery by lowering either FIO(2) or blood volume.


RESULTS
In hypoxic hypoxia pigs (n = 6), arterial oxygen concentration and oxygen delivery decreases were achieved by progressively reducing arterial PO(2) while cardiac index remained unchanged. In ischemic hypoxia pigs (n = 5), oxygen delivery reduction was achieved by progressively reducing cardiac index while arterial PO(2) remained unchanged. In control pigs, oxygen delivery remained unchanged. The lowest oxygen delivery measured in both hypoxia and ischemia experiments was 3.60 +/- 0.26 vs. 2.93 +/- 0.77 mL x kg(-1) x min(-1), respectively (p =.23). At the lowest oxygen delivery level, differences between ischemic hypoxia and hypoxic hypoxia experiments were observed for arterial lactate concentration (468 +/- 308 vs. 1070 +/- 218 mmol/L, respectively; p =.03), mixed venous arterial PCO(2) difference (10 +/- 7 vs. 4 +/- 2 torr, respectively; p =.04), and small intestine mucosal blood flow (6.2 +/- 2.1 vs. 15.7 +/- 7.4 perfusion units, respectively; p =.02). Small intestine intramucosal-arterial difference was higher in ischemic hypoxia than in hypoxic hypoxia (52 +/- 15 vs. 31 +/- 12 torr, respectively; p =.03).


CONCLUSIONS
Small intestine intramucosal PCO(2) increases may indicate systemic oxygen uptake supply limitation in ischemic and hypoxic hypoxia related to conditions of mucosal flow stagnation and CO(2) generation.
Nevière
Rémi
R
Service de Réanimation Médicale et de Médecine Hyperbare, Hôpital Calmette, Lille, France.
Chagnon
Jean-Luc
JL
Teboul
Jean-Louis
JL
Vallet
Benoit
B
Wattel
Francis
F
D000704:Analysis of Variance; D000818:Animals; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D000860:Hypoxia / Q000503:physiopathology*; D007413:Intestinal Mucosa / Q000098:blood supply* / Q000378:metabolism; D007421:Intestine, Small / Q000098:blood supply* / Q000378:metabolism; D007511:Ischemia / Q000503:physiopathology*; D008365:Manometry; D008833:Microcirculation; D010313:Partial Pressure; D011897:Random Allocation; D012039:Regional Blood Flow; D018709:Statistics, Nonparametric; D013552:Swine
D002245:Carbon Dioxide