Cardiorespiratory impact of intrathoracic pressure overshoot during artificial carbon dioxide pneumothorax: a randomized controlled study

Background The aim of this study is to evaluate cardiovascular and respiratory effects of intrathoracic pressure overshoot (higher than insufflation pressure) in patients who underwent thoracoscopic esophagectomy procedures with carbon dioxide (CO 2 ) pneumothorax. Methods This prospective research included 200 patients who were scheduled for esophagectomy from August 2016 to July 2020. The patients were randomly divided into the Stryker insufflator (STR) group and the Storz insufflator (STO) group. We recorded the changes of intrathoracic pressure, peak airway pressure, blood pressure, heart rate and central venous pressure (CVP) during artificial pneumothorax. The differences in blood gas analysis, the administration of vasopressors and the recovery time were compared between the two groups. Results We found that during the artificial pneumothorax, intrathoracic pressure overshoot occurred in both the STR group (8.9 mmHg, 38 times per hour) and the STO group (9.8 mmHg, 32 times per hour). The recorded maximum intrathoracic pressures were up to 58 mmHg in the STR group and 51 mmHg in the STO group. The average duration of intrathoracic pressure overshoot was significantly longer in the STR group (5.3 ± 0.86 s) vs. the STO group (1.2 ± 0.31 s, P < 0.01). During intrathoracic pressure overshoot, a greater reduction in systolic blood pressure (SBP) (5.6 mmHg vs. 1.1 mmHg, P < 0.01), a higher elevation in airway peak pressure (4.8 ± 1.17 cmH 2 O vs. 0.9 ± 0.41 cmH 2 O, P < 0.01), and a larger increase in CVP (8.2 ± 2.86 cmH 2 O vs. 4.9 ± 2.35 cmH 2 O, P < 0.01) were observed in the STR group than in the STO group. Vasopressors were also applied more frequently in the STR group than in the STO group (68% vs. 43%, P < 0.01). The reduction of SBP caused by thoracic pressure overshoot was significantly correlated with the duration of overshoot ( R = 0.76). No obvious correlation was found between the SBP reduction and the maximum pressure overshoot. Conclusions Intrathoracic pressure overshoot can occur during thoracoscopic surgery with artificial CO 2 pneumothorax and may lead to cardiovascular adverse effects which highly depends on the duration of the pressure overshoot. Trial registration Clinicaltrials.gov ( NCT02330536 ; December 24, 2014).