The effects of the lateral position on cardiopulmonary function during laparoscopic urological surgery

Difference in the value of arterial and end-tidal carbon dioxide tension according to different surgical positions: Does it reliably reflect ventilation-perfusion mismatch?

Background

Body posture, as a gravitational factor, has a clear impact on pulmonary ventilation and perfusion. In lung units with mismatched ventilation and perfusion, gas exchange and/or elimination of carbon dioxide can be impaired. In this situation, differences in the value of arterial and end-tidal carbon dioxide tension [Δ(PaCO₂ - P_ETCO₂)] are expected to increase. This study was conducted to observe how Δ(PaCO₂ - P_ETCO₂) changed according to the 3 different surgical positions, and to determine whether Δ(PaCO₂ - P_ETCO₂) is a reliable predictor of ventilation/perfusion mismatch when a patient is in different postural positions.

Methods

Fifty-nine patients were divided into either the chronic obstructive pulmonary disease (COPD) group (n = 29) or the non-COPD group (n = 30). PaCO₂ and P_ETCO₂ were measured during surgery in the supine, prone, and lateral decubitus positions after a 10 minute stabilization period. The Δ(PaCO₂ - P_ETCO₂) were calculated and compared among positions.

Results

The Δ(PaCO₂ - P_ETCO₂) decreased slightly in the prone position and increased significantly in the lateral decubitus position compared with the supine position in both groups. These patterns almost corresponded with the degree of ventilation/perfusion mismatch from the results of the radiological studies. The Δ(PaCO₂ - P_ETCO₂) in the COPD group was significantly greater than that in the non-COPD group at all surgical positions.

Conclusions

Lateral decubitus position is associated with marked increase in Δ(PaCO₂ - P_ETCO₂), especially in patients with COPD. The Δ(PaCO₂ - P_ETCO₂) is a simple and reliable indicator to predict ventilation/perfusion mismatch at different surgical positions in patients with or without COPD.

Laparoscopic surgery: pitfalls due to anesthesia, positioning, and pneumoperitoneum

BACKGROUND

Laparoscopic procedures are increasing in number and extensiveness. Many patients undergoing laparoscopic surgery have coexisting disease. Especially in patients with cardiopulmonary comorbidity, pneumoperitoneum and positioning can be deleterious. This article reviews possible pitfalls related to the combination of anesthesia, positioning of the patient, and the influence of pneumoperitoneum in the course of laparoscopic interventions.

METHODS

A literature search using Medline's MESH terms was used to identify recent key articles. Cross-references from these articles were used as well.

RESULTS

Patient positioning and pneumoperitoneum can induce hemodynamic, pulmonary, renal, splanchnic, and endocrine pathophysiological changes, which will affect the entire perioperative period of patients undergoing laparoscopic procedures.

CONCLUSION

Perioperative management for the estimation and reduction of risk of morbidity and mortality due to surgery and anesthesia in laparoscopic procedures must be based on knowledge of the pathophysiological disturbances induced by the combination of general anesthesia, pneumoperitoneum, and positioning of the patient.