The use of capnometry to predict arterial partial pressure of CO2 in non-intubated breathless patients in the emergency departmentReport as inadecuate

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International Journal of Emergency Medicine

, Volume 3, Issue 4, pp 315–320

1.To determine the correlation between end tidal CO2 and PaCO2 in non-intubated acutely breathless patients.

 2.To determine factors that influence the end tidal carbon dioxide ETCO2.

 3.To determine the correlation between ETCO2 with PaCO2 in patients presenting with pulmonary disorders.

 MethodsOne hundred fifty acutely breathless patients arriving at the emergency department and fulfilling the inclusion and exclusion criteria were chosen during a 6-month study period. The patients gave written or verbal consent, and were triaged and treated according to their presenting complaints. Demographic data were collected, and the ETCO2 data were recorded. Arterial blood gas was taken in all patients. The data were compiled and analyzed using various descriptive studies from the Statistics Program for Social Studies SPSS version 12. Correlation between ETCO2 and PaCO2 was analyzed using the Pearson correlation coefficient. Other variables also were analyzed to determine the correlation using simple linear regression. The agreement and difference between ETCO2 and PaCO2 were analyzed using paired sample t-tests.

ResultsThere is a strong correlation between ETCO2 and PaCO2 using the Pearson correlation coefficient: 0.716 and p value of 0.00 p < 0.05. However, the paired t-test showed a mean difference between the two parameters of 4.303 with a p value < 0.05 95% CI 2.818, 5.878. There was also a good correlation between ETCO2 and acidosis state with a Pearson correlation coefficient of 0.374 and p value 0.02 p < 0.05. A strong correlation was also observed between ETCO2 and a hypocapnic state, with a Pearson correlation coefficient of 0.738 p < 0.05. Weak correlation was observed between alkalosis and ETCO2, with a Pearson correlation coefficient of 0.171 p < 0.05. A strong negative correlation was present between ETCO2 and hypercapnic patients presenting with pulmonary disorders, with a Pearson correlation coefficient of -0.738 p < 0.05 and of -0.336 p < 0.05, respectively.

ConclusionThis study shows that ETCO2 can be used to predict the PaCO2 level when the difference between the PaCO2 and ETCO2 is between 2 to 6 mmHg, especially in cases of pure acidosis and hypocapnia. Using ETCO2 to predict PaCO2 should be done with caution, especially in cases that involve pulmonary disorders and acid-base imbalance.

KeywordsCapnometry End tidal Dyspnea Blood gas DisclaimerThe views expressed in this paper are those of the authors and not those of the editors, editorial board or publisher.

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Author: Nik Hisamuddin Nik Ab Rahman - Amiruddin Fairuz Mamat


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