Question

how can weaning affect the patient's arterial carbon dioxide

Answer 1

The patients were weaned from mechanical ventilation in an average time of 6.5 +/- 1.5 hours. A plot of SaO2 versus SpO2 indicated a high correlation with sensitivity (100%) for hypoxemia (SaO2 less than 90%). P(ET)CO2 was a good indicator of PaCO2 ; its sensitivity to detect hypercarbia (PaCO2 less than 45 mmHg) was 95%. The gradient between SpO2 and SaO2 was not significantly affected by the weaning process, but the PaCO2-P(ET)CO2 gradient decreased significantly as the ventilator rate was decreased (p less than 0.001). The weaning process was discontinued on four separate occasions because of metabolic acidosis. Ninety-five percent of arterial blood samples confirmed the weaning recommendations based on the continuous monitoring of SpO2 and P(ET)CO2.

Conclusions: Continuous monitorin of SpO2 and P(ET)CO2 can be used to wean patients safely and effectively after CABG when adjustment of minute ventilation compensates for an increased PaCO2-P(ET)CO2 gradient during controlled ventilation.