Evaluation of Intraoperative End-Tidal Carbon Dioxide Change Relates to Length Hospitalisation in Peridiaphragmatic Surgery: A Pilot Study

Intraoperative evaluation is deeply changed using many new tools, both invasive and non-invasive. Peripheral oxygen saturation percentage (SpO2) is the more reliable method for a non-invasive monitoring of patient’s blood oxygen concentration. Capnography (using end-tidal CO2 (EtCO2)) evaluation is an immediate and continuous non-invasive monitoring of carbon dioxide (CO2) in the breathing that provides important information on circulatory status and ventilation. Aim of this study is to perform a preliminary analysis of oxygen change during surgery exploring its possible influence on post-operative evolution. Methods and results: Intraoperative evaluation of SpO2 and EtCO2 was performed. Change in each parameter was categorised as 1 point for each five-point variation from baseline value (∆SpO2 as 1 point for each 5%, ∆EtCO2 as 1 point for each 5 mmHg). For each patient, the length of stay (LOS) in the intensive care unit (ICU), total hospitalisation, duration of intervention, surgical risk and complications were recorded. Results: We analysed 93 consecutive patients (43 males and 40 females, aged 66.35 ± 9.79 years) that underwent peridiaphragmatic surgery. Forty patients (48.19%) presented complications after surgery. There was no statistically significant difference in age, duration of intervention and length of stay in ICU between complicated and non-complicated patients. As expected, patients with complications present an increased hospitalisation time compared to uncomplicated cases (14.69 ± 11.41 days vs 10.70 ± 6.28 days; p < 0.05). ∆EtCO2 was significantly increased (p < 0.05) in complicated compared to non-complicated. No differences were found in ∆SpO2 between the two groups. Considering the whole population, ∆EtCO2 presents a significant direct correlation to surgical risk, hospitalisation and duration of intervention. Conclusion: ∆EtCO2 may be related to possible complications after surgery and hospitalisation. An important comparison between SpO2 and EtCO2 and strict monitoring with an intraoperative arterial blood gas (ABG) sample during the main steps of surgery could bring some essential information to understand oxygen changes in intra- and post-operative evolution. However, a further validation analysis is needed before the approach can be used extensively in daily clinical settings.