Tonometry revisited: perfusion-related, metabolic, and respiratory components of gastric mucosal acidosis in acute cardiorespiratory failure.

摘要

Mucosal pH (pHi) is influenced by local perfusion and metabolism (mucosal-arterial pCO2 gradient, DeltapCO2), systemic metabolic acidosis (arterial bicarbonate), and respiration (arterial pCO2). We determined these components of pHi and their relation to outcome during the first 24 h of intensive care. We studied 103 patients with acute respiratory or circulatory failure (age, 63+/-2 [mean+/-SEM]; Acute Physiology and Chronic Health Evaluation II score, 20+/-1; Sequential Organ Failure Assessment score, 8+/-0). pHi, and the effects of bicarbonate and arterial and mucosal pCO2 on pHi, were assessed at admission, 6, and 24 h. pHi was reduced (at admission, 7.27+/-0.01) due to low arterial bicarbonate and increased DeltapCO2. Low pHi (or=7.32 at admission; P=0.061) was associated with an increased DeltapCO2 in 59% of patients (mortality, 47% vs. 4% for patients with low pHi and normal DeltapCO2; P=0.0003). An increased versus normal DeltapCO2, regardless of pHi, was associated with increased mortality at admission (51% vs. 5%; P<0.0001; n=39) and at 6 h (34% vs. 13%; P=0.016; n=45). A delayed normalization or persistently low pHi (n=47) or high DeltapCO2 (n=25) was associated with high mortality (low pHi [34%] vs. high DeltapCO2 [60%]; P=0.046). In nonsurvivors, hypocapnia increased pHi at baseline, 6, and 24 h (all P