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Anesth Essays Res. 2019 Jul-Sep;13(3):583-588. doi: 10.4103/aer.AER_88_19.

Evaluation of Arterial to End-tidal Carbon Dioxide Pressure Differences during Laparoscopic Renal Surgery in the Lateral Decubitus Position.

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Department of Anaesthesia and Intensive Care, Fortis Hospital Mohali, Chandigarh, India.
Department of Anaesthesia and Intensive Care, PGIMER, Chandigarh, India.
Department of Renal Transplant Surgery, PGIMER, Chandigarh, India.



End-tidal carbon dioxide (PEtCO2) is a noninvasive reliable technique to measure arterial partial pressure of carbon dioxide (PaCO2) in the body under general anesthesia. However, gradient between PaCO2 and PEtCO2 (P[a-Et] CO2) is influenced by many factors.


In the present study, we evaluated the changes in P (a-Et) CO2 for laparoscopic donor nephrectomy in lateral decubitus position (LDP).

Settings and Design:

This was an observational, double-blinded, tertiary care center-based study.


Thirty-one American Society of Anesthesiologists Class I and Class II patients of either sex undergoing laparoscopic donor nephrectomy in LDP under general anesthesia were included. An arterial cannula was inserted, PaCO2 was measured at eight predesignated time intervals, and PEtCO2 was also noted at the corresponding time period.

Statistical Analysis:

Data were analyzed using a two-way analysis of variance for repeated measurements using one dependent variable and one within-subject factor (time). Quantitative data were presented as mean ± standard deviation or median and interquartile range, as appropriate.


The mean P (a-Et) CO2 gradient was 5.67 ± 1.36 mmHg 10 min after induction of anesthesia in the supine position (T1a). Ten minutes after LDP, P (a-Et) CO2 gradient was 7.38 ± 1.45 mmHg (T1b) and was higher than T1a. The P (a-Et) CO2 values 10 min after release of pneumoperitoneum and 10 min after making the patient supine were significantly higher than the T1a value. The highest value of P (a-Et) CO2 gradient was at 30 min after creation of pneumoperitoneum (T30), i.e., 9.99 ± 1.70 mmHg. Pearson's correlation coefficient showed that the degree of correlation varied considerably during surgery due to interindividual variability (R 2 T1a vs. T60 was 0.61 vs. 0.17).


PEtCO2 does not reliably predict PaCO2 in healthy patients scheduled for laparoscopic renal surgery in LDP.


Carbon dioxide; laparoscopic surgery; lateral decubitus position; partial pressure; pneumoperitoneum

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