The Application of Transcutaneous CO2 Pressure Monitoring in the Anesthesia of Obese Patients Undergoing Laparoscopic Bariatric Surgery

Shijiang Liu,Yingying Yu,Cunming Liu,Jie Sun,Xing Chen,Xuan Liu,Zhongcong Xie

doi:10.1371/journal.pone.0091563

Abstract

To investigate the correlation and accuracy of transcutaneous carbon dioxide partial pressure (PTCCO2) with regard to arterial carbon dioxide partial pressure (PaCO2) in severe obese patients undergoing laparoscopic bariatric surgery. Twenty-one patients with BMI>35 kg/m2 were enrolled in our study. Their PaCO2, end-tidal carbon dioxide partial pressure (PetCO2), as well as PTCCO2 values were measured at before pneumoperitoneum and 30 min, 60 min, 120 min after pneumoperitoneum respectively. Then the differences between each pair of values (PetCO2–PaCO2) and. (PTCCO2–PaCO2) were calculated. Bland–Altman method, correlation and regression analysis, as well as exact probability method and two way contingency table were employed for the data analysis. 21 adults (aged 19–54 yr, mean 29, SD 9 yr; weight 86–160 kg, mean119.3, SD 22.1 kg; BMI 35.3–51.1 kg/m2, mean 42.1,SD 5.4 kg/m2) were finally included in this study. One patient was eliminated due to the use of vaso-excitor material phenylephrine during anesthesia induction. Eighty-four sample sets were obtained. The average PaCO2–PTCCO2 difference was 0.9±1.3 mmHg (mean±SD). And the average PaCO2–PetCO2 difference was 10.3±2.3 mmHg (mean±SD). The linear regression equation of PaCO2–PetCO2 is PetCO2 = 11.58+0.57×PaCO2 (r2 = 0.64, P<0.01), whereas the one of PaCO2–PTCCO2 is PTCCO2 = 0.60+0.97×PaCO2 (r2 = 0.89). The LOA (limits of agreement) of 95% average PaCO2–PetCO2 difference is 10.3±4.6 mmHg (mean±1.96 SD), while the LOA of 95% average PaCO2–PTCCO2 difference is 0.9±2.6 mmHg (mean±1.96 SD). In conclusion, transcutaneous carbon dioxide monitoring provides a better estimate of PaCO2 than PetCO2 in severe obese patients undergoing laparoscopic bariatric surgery.

Highlights

The ‘‘gold standard’’ technique for the measurement of arterial carbon dioxide partial pressure (PaCO2) is performed by direct analysis of arterial blood gases (ABG), but this method is invasive, intermittent and may cause iatrogenic anemia in infants
The end-tidal carbon dioxide partial pressure (PetCO2) measurement has been widely used for the continuous noninvasive monitoring of carbon dioxide in patients with tracheal intubation during general anesthesia, many factors may possibly affect the accuracy of PetCO2 monitoring, such as mismatch of ventilation to blood flow (V/Q ratio), chronic obstructive pulmonary disease, obstructive sleep apnea syndrome, surgery postures, smoking, ect
The PaCO2, PetCO2, and PTCCO2 values were recorded at 4 time points

Summary

Introduction

The ‘‘gold standard’’ technique for the measurement of arterial carbon dioxide partial pressure (PaCO2) is performed by direct analysis of arterial blood gases (ABG), but this method is invasive, intermittent and may cause iatrogenic anemia in infants. Noninvasive transcutaneous carbon dioxide partial pressure (PTCCO2) monitoring has been used in infants and in adult patients with good accuracy [1,2,3]. PetCO2 in estimate of PaCO2 for sever obesity undergoing open bariatric surgery, but the accuracy and correlation between PaCO2 measurements and PTCCO2 monitoring for patients with laparoscopic bariatric surgery is still unknown. We designed the present study to evaluate the accuracy and correlation of estimating PaCO2 using a PTCCO2 monitor in severe obese patients undergoing laparoscopic bariatric surgery

Methods

Results

Conclusion