# Impact of constant low gas pressure on cardiopulmonary parameters and surgical outcomes in extraperitoneal total nerve-sparing robot-assisted radical prostatectomy

## TL;DR

This study compares the effects of low CO2 pressure (8 mmHg) versus standard pressure (12 mmHg) in robot-assisted prostate surgery, finding that lower pressure reduces CO2 absorption without increasing complications.

## Contribution

The study introduces the use of constant low CO2 pressure in extraperitoneal prostate surgery, potentially expanding eligibility for patients with respiratory conditions.

## Key findings

- Lower CO2 pressure (8 mmHg) reduced carbon dioxide absorption into the bloodstream compared to standard pressure (12 mmHg).
- No significant differences in operative time, blood loss, or complications were observed between the two pressure groups.
- Low-pressure insufflation may enhance safety and tolerability for patients with chronic pulmonary diseases.

## Abstract

Traditionally, in extraperitoneal robot-assisted radical prostatectomy (EP-RARP), a pneumo-Retzius is obtained by using a CO2 insufflation pressure of 12–15 mmHg. However, EP surgery is associated with an increase in CO2 absorption and consequent hypercapnia and acidosis. This study aimed to compare the effect of low CO2 pressure (8 mmHg) with the conventional gas pressure in EP-RARP. We enrolled patients with low-risk prostate cancer who had undergone total nerve-sparing RARP using our PERUSIA (Posterior, Extraperitoneal, Robotic, Under Santorini, Intrafascial, Anterograde) technique. The exclusion criteria were the presence of chronic lung disease, a positive biopsy core from the anterior zone, or a shift to a transperitoneal approach. Cardiopulmonary parameters were measured at the induction of anesthesia (T0); at 5 (T1) and 60 (T2) minutes after starting CO₂ insufflation; and immediately after dorsal venous complex dissection before urethro-vesical anastomosis (T3). Data from 120 consecutive patients were retrospectively analyzed from a prospectively maintained database. Patients were divided into two groups based on the CO2 insufflation pressure (8 vs. 12 mmHg). No significant differences were detected in mean operative time, time required for trocar positioning, mean estimated blood loss, or complications between the two groups. The only significant difference was in the partial pressure of carbon dioxide, which was higher at T3 in Group 2 (p=0.005), with a consequent reduction in arterial pH. However, no significant difference (p = 0.44) was found regarding acidosis between the two groups at all timepoints. RARP has become a standard procedure in urological surgery for the treatment of localized prostate cancer. However, the CO2 insufflation required to create a surgical workspace may lead to cardiopulmonary complications, especially in patients with pre-existing respiratory conditions. This study compared the effects of a lower insufflation pressure (8 mmHg) vs. the standard pressure (12 mmHg) during EP-RARP. The findings suggest that using a low and constant pressure can reduce CO2 absorption into the bloodstream without increasing intraoperative or postoperative complications. This approach may expand eligibility for EP-RARP to include patients with chronic pulmonary diseases by enhancing the safety and tolerability of the procedure.