Journal Article

Influence of alveolar ventilation changes on calculated gastric intramucosal pH and gastric-arterial PCO2 difference

Hyvernat, H., Bernardin, G., Deloffre, P., Lucas, P., Mattéi, M.

1999

Overview

To evaluate the influence of changes in alveolar ventilation on the following tonometry-derived variables: gastric intramucosal CO2 tension (PtCO2), gastric arterial CO2 tension difference (PgapCO2), gastric intramucosal pH (pHi) and arterial pH-pHi difference (pHgap). Clinical prospective study. A medical intensive care unit in a university hospital. Ten critically ill, mechanically ventilated patients requiring hemodynamic monitoring with pulmonary artery catheter. Gastric tonometer placement. A progressive increase in tidal volume (V(T)) from 7 to 10 ml/ kg followed by an abrupt return to baseline V(T) level. Tonometer saline PtCO2 and hemodynamic data were collected hourly at various V(T) levels: H0 and H0' (baseline V(T) = 7 ml/kg), H1 (V(T) = 8 ml/kg), H2 (V(T) = 9 ml/kg), H3 (V(T) = 10 ml/kg), H4 (baseline V(T)). During the \"hyperventilation phase\" (H0-H3), pHi (p<0.01) and pHgap (p<0.05) increased but PgapCO2 remained unchanged. Cardiac output (CO) was not affected by ventilatory change. During the \"hypoventilation phase\" (H3-H4), pHi fell from 7.27+/-0.11 to 7.23+/-0.09 (p<0.01) and PgapCO2 decreased from 16+/-5 mm Hg to 13+/-4 mm Hg (p<0.05). V(T) reduction was associated with a significant cardiac output elevation (p<0.05). PaCO2 and PtCO2 are similarly influenced by the changes in alveolar ventilation. Unlike pHi, the PgapCO2 is not affected by ventilation variations unless CO changes are associated.

• Publisher: Springer,Springer Nature B.V
• Subject: Alveoli / Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy / Biological and medical sciences / Blood Gas Analysis - methods / Carbon dioxide / Carbon Dioxide - metabolism / Cardiac output / Catheters / Critical Illness / Emergency and intensive respiratory care / Female / Gastric Mucosa - blood supply / Gastric Mucosa - metabolism / Heart / Hemodynamics / Humans / Hydrogen-Ion Concentration / Hyperventilation / Hypoventilation / Intensive care / Intensive care medicine / Male / Manometry - methods / Mechanical ventilation / Medical sciences / Middle Aged / Multiple organ dysfunction syndrome / Patients / pH effects / Prospective Studies / Pulmonary arteries / Pulmonary artery / Respiration, Artificial / Sepsis / Severity of Illness Index / Veins & arteries / Ventilation / Ventilators