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Weaning with end-tidal CO2 and pulse oximetry
D N Thrush1, S W Mentis, J B Downs
1Department of Anesthesiology, University of South Florida College of Medicine, Tampa 33601.
Journal of Clinical Anesthesia
|November 1, 1991
Summary
Continuous monitoring of arterial oxyhemoglobin saturation (SpO2) and end-tidal carbon dioxide (P(ET)CO2) safely and effectively weans cardiac surgery patients from mechanical ventilation. This method accurately guides weaning decisions, reducing the need for frequent blood gas analysis.
Area of Science:
- Cardiology
- Pulmonology
- Critical Care Medicine
Background:
- Mechanical ventilation is crucial post-cardiac surgery.
- Weaning from mechanical ventilation requires careful monitoring.
- Existing methods may involve invasive procedures or less frequent assessments.
Purpose of the Study:
- To evaluate the efficacy of continuous SpO2 and P(ET)CO2 monitoring for safe and efficient weaning from mechanical ventilation after cardiac surgery.
- To compare continuous monitoring data with arterial blood gas analysis.
- To assess the correlation and sensitivity of SpO2 and P(ET)CO2 in guiding the weaning process.
Main Methods:
- A prospective study was conducted in a cardiac surgical intensive care unit.
- Ten patients undergoing coronary artery bypass grafting (CABG) were monitored postoperatively during mechanical ventilation weaning.
- Continuous SpO2 and P(ET)CO2 measurements were compared with arterial oxygen saturation (SaO2) and arterial carbon dioxide tension (PaCO2) from blood gas analysis.
Main Results:
- Patients were weaned in an average of 6.5 hours.
- SpO2 showed a high correlation (r=0.84) with SaO2, with 100% sensitivity for hypoxemia.
- P(ET)CO2 correlated well with PaCO2 (r=0.76), demonstrating 95% sensitivity for hypercarbia. 95% of blood gas samples confirmed weaning recommendations.
Conclusions:
- Continuous SpO2 and P(ET)CO2 monitoring is a safe and effective method for weaning cardiac surgery patients.
- This approach can reduce the need for frequent arterial blood gas sampling.
- Adjusting minute ventilation to manage the PaCO2-P(ET)CO2 gradient is important during controlled ventilation.