The Predictive Value of MAP and ETCO2 Changes After Emergency Endotracheal Intubation for Severe Cardiovascular Collapse

Objective: To analyze the changes in mean arterial pressure (MAP) and end-tidal CO2 (ETCO2) in patients after emergency endotracheal intubation (ETI). To explore the values of MAP and ETCO2 monitoring in the early prediction of severe cardiovascular collapse (CVC). Methods: The clinical data of patients who underwent ETI were collected. The values of both MAP and ETCO2 were observed and recorded at 5 minutes, 10 minutes, 30 minutes, 60 minutes and 120 minutes post intubation. According to whether severe CVC occurred after ETI, the patients were divided into a severe CVC group and a non-severe CVC group. The values of MAP and ETCO2 were compared at the same time points. The correlation between MAP and ETCO2 after ETI was also analyzed. receiver operating characteristic curves(ROC curves) were used to analyze the ability of MAP and ETCO2 at 5 minutes and 10 minutes after ETI to predict severe CVC.Results: A total of 116 patients were enrolled in this study; among them, 75 (64.7%) had severe CVC after ETI. The majority of subjects in the severe CVC group were male and elderly patients. The values of MAP and ETCO2 at 5 minutes, 10 minutes, 30 minutes, 60 minutes and 120 minutes after ETI in the severe CVC group were significantly lower than those in the non-severe group. Both MAP and ETCO2 in the two groups showed simultaneous decreases from 5 minutes to 30 minutes after ETI, reaching their lowest values at 30 minutes after ETI. After ETI, the changes in MAP were correlated with those in ETCO2 (rs = 0.653, P < 0.001). At 5 minutes after ETI, MAP could predict severe CVC (AUC = 0.86, P < 0.001), MAP≤72 mmHg was the best cutoff value (sensitivity 78.7%, specificity 87.8%), and ETCO2 could also predict severe CVC (AUC = 0.85, P < 0.001). ETCO2≤35 mmHg was the best cutoff value for predicting severe CVC (sensitivity 77.3%, specificity 85.4%). At 10 minutes after ETI, MAP could predict severe CVC (AUC = 0.90, P < 0.001), MAP≤67 mmHg was the best cutoff value (sensitivity 89.3%, specificity 85.4%), and ETCO2 could also predict severe CVC (AUC = 0.87, P < 0.001). ETCO2≤33 mmHg was the best cutoff value for predicting severe CVC (sensitivity 81.3%, specificity 78%). There was no significant difference in the predictive ability between any two cutoff values of MAP or ETCO2 at 5 minutes and 10 minutes after ETI (P >0.05). Conclusion: Both MAP and ETCO2 values of the patients with severe CVC were significantly lower than those of patients without severe CVC from 5 minutes to 120 minutes after ETI, reaching their lowest values at 30 minutes after ETI. MAP and ETCO2 values changed synchronously with the time after intubation. There was a positive correlation between MAP and ETCO2 after ETI. MAP and ETCO2 values in the early stage after ETI have high accuracy in predicting severe CVC.