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

Abstract

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 (CO2) 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 cmH2O vs. 0.9 ± 0.41 cmH2O, P < 0.01), and a larger increase in CVP (8.2 ± 2.86 cmH2O vs. 4.9 ± 2.35 cmH2O, 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 CO2 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).

Keywords: Capnothorax; Insufflator; Intrathoracic pressure; Overshoot; Thoracoscopy.

Conflict of interest statement

None of the authors have declared a conflict of interest.

© 2022. The Author(s).

Figures

Fig. 1

Thoracoscopic procedures of thoracoscopic-laparoscopic esophagectomy. a Patients were placed in the semi-prone position and four trocars were placed at four sites. b-d Intraoperative images during artificial pneumothorax

Fig. 2

Examples for intrathoracic pressure changes in the STR and the STO group. a Typical graph of intrathoracic pressure changes in the STR group during artificial pneumothorax within 60 min. b A detailed view of the changes in intrathoracic pressure during the 500 – 560 s in a. c Typical graph of intrathoracic pressure changes in the STO group during artificial pneumothorax within 60 min. d A detailed view of the changes in intrathoracic pressure during the 350 – 410 s in c

Fig. 3

The correlation between the SBP reduction and the magnitude of pressure overshoot, duration of overshoot, increase of peak airway pressure and increase of CVP, respectively. a Scatter plot of the magnitude of pressure overshoot and the SBP reduction. b Scatter plot of the duration of overshoot and the SBP reduction. c Scatter plot of the increase in peak airway pressure and the SBP reduction. d Scatter plot of the increase in CVP and the SBP reduction. e Trend graph showed the relationship between the duration of pressure overshoot and the incidence of SBP drop (defined as SBP drop was more than 5 mmHg during pressure overshoot)