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

Abstract

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.