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Updated: Jun 5, 2025
Noninvasive Determination of Vortex Formation Time Using Transesophageal Echocardiography During Cardiac Surgery
Published on: November 28, 2018
Different measures of ventilatory efficiency in preoperative cardiopulmonary exercise testing are useful for
Elin Stark1, Edvard Gerring2, Johan Hylander3
1Department of Anaesthesiology and Intensive Care, Centre for Clinical Research, Sörmland, Nyköping Hospital, Nyköping, Sweden.
Background:
Ventilation as a function of elimination of CO2 during incremental exercise (VE/VCO2 slope) has been shown to be a valuable predictor of complications and death after major non-cardiac surgery. VE/VCO2 slope and partial pressure of end-tidal carbon dioxide (PetCO2) are both affected by ventilation/perfusion mismatch, but research on the utility of PetCO2 for risk stratification in major abdominal surgery is limited.
Aim:
We aimed to determine the correlation between VE/VCO2 slope and PetCO2 measured during preoperative cardiopulmonary exercise testing (CPET) and its association with major cardiopulmonary complications (MCPCs) or death following oesophageal and other major abdominal cancer surgeries.
Method:
In a retrospective cohort of 116 patients undergoing preoperative CPET 2008-2023, VE/VCO2 slope and PetCO2 (kPa) were recorded. The main outcome was MCPC during hospitalisation or death ≤90 days of surgery. We determined threshold values for each measure, corresponding to 90% specificity, using receiver operating characteristics analysis.
Results:
A strong negative correlation was found between PetCO2 after a 5-minute warm-up and VE/VCO2 slope (Pearson r = -.88). In oesophagus cancer, VE/VCO2 slope >38 and PetCO2 < 4.1 kPa (30.8 mmHg) were both significant thresholds for the main outcome. For other major abdominal surgery patients, threshold analyses were non-significant. The area under the curve to predict outcome was similar using VE/VCO2 slope (0.70, 95% confidence interval 0.51-0.89) as compared to PetCO2 (0.71, 0.53-0-90).
Conclusion:
Both preoperative VE/VCO2 slope and PetCO2 could identify subjects with a very high risk of complications following oesophageal resection, with similar prognostic utility. PetCO2 can be measured with simpler equipment and could therefore be useful when CPET is not available.
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