Effect of peri-intubation ETCO2 value on cerebral oximetry

. ABSTRACT Effect of Peri-Intubation ETCO2 Value on Cerebral Oximetry Rapid sequence intubation (RSI) is the standard of care for the patients who cannot maintain adequate oxygenation and ventilation despite less invasive interventions. Some of these steps in the RSI protocol may have detrimental hemodynamic effects even if applied correctly due to the clinical status of the patient. Cerebral oximetry is an Food and Drug Administration (FDA) approved, non-invasive near-infrared spectrometry device and it measures regional cerebral oxygen saturation (rSO2) from the surface portion of the brain. End-tidal Carbon Dioxide (ETCO2), is frequently measured in the Emergency Department. ETCO2 can give information to the care givers in terms of endotracheal tube position, resuscitation quality and acid-base status. The aim of the present study is to reveal factors related to peri-intubation hemodynamic compromise and to reveal the association between ETCO2, peri-intubation hemodynamic compromise and cerebral oximetry. Materials and Methods In this prospective study, patients who were 18 years or older and intubation decision was given at the discretion of their primary physician were included. rSO2 and ETCO2 measurements are performed continuously. Blood pressure readings just before the intubation and immediate post-intubation and 3 more readings every 10 minutes were recorded. After 30 minutes of rSO2 and ETCO2 recordings, the study was stopped for the patient. ≥25% decrease in cerebral oximetry reading from baseline was accepted cerebral hypoperfusion. Results The data of 76 patients were included in the current study. The mean age of the study population was 65.5±19.8. The reason for intubation of the study population was trauma in 12% and 88% for general medical conditions. Mean and median rSO2 values were 60.1±20 ve 63 (IQR 51-72.5), respectively. A Substantial number of patients had hemodynamic compromise after intubation (46.7%). Pre-intubation blood pressure readings either systolic or diastolic were statistically significantly higher than immediate, 10, 20 or 30 minutes post-intubation (p<0.001). ≥25% decrease in cerebral oximetry readings was detected in 13% of the patients and there was a weak and a negative correlation between cerebral oximetry and peri-intubation hemodynamic instability and a again a weak correlation between ETCO2 and rSO2 [r=0.30 (p=0.06)] was detected. Conclusion Although hemodynamic compromise is rather common in ED RSI, it seems that it does not affect cerebral oxygenation. Key Words: Capnometry, Cerebral Blood Flow, Hemodynamic Instability, Rapid Sequential Intubation, Cerebral Oximeter