CO2 consumption
To estimate the CO2 emissions related to robotic and laparoscopic procedures, the first step was to separate the contributing components into the scope of emission. Scope 1, as defined by the GHG protocol, involves the direct emissions from sources. Scope 2 involves the indirect emissions that result from the generation of electricity, disposal of single-use devices, and heating, cooling, production, and sterilization of instruments. Scope 1 emissions involve the CO2 used during the surgical procedures necessary for insufflation. CO2 escapes into the atmosphere both directly and indirectly—directly, CO2 escapes via leaks in the port sites, decompression of insufflation at the end of the surgery, or inadvertently; indirectly, patients will absorb CO2 in intra-abdominal organs which will be eliminated through the respiratory system.
A typical CO2 cylinder used in our institution’s operating room contains compressed gas. Using the ideal gas law, 1 mol of any gas occupies 22.4 L at 1 atm. Because 1 mol of CO2 weighs 44 g, there are \(1.5\bullet {10}^{-4}\) metric tons of CO2 in one cylinder. To estimate the operative time per cylinder, we calculated the operative times for both robot-assisted and laparoscopic radical prostatectomy procedures.
LCA
The performance of LCA, a powerful method for designing and evaluating the sustainability of green processes, is often used as a support for the deliberation of phase choices made by public or private subjects (public authorities and manufacturers). The LCA of “typical” equipment with “average” characteristics compared to the set of machines considered is intended to quantify the expected impact on medium- or large-scale (regional, national, and community), which offers the possibility of identifying the factors most critical to the global impact. Therefore, the estimates are related to a model of intervention between the two techniques, using existing databases or developed specifically for the purpose; they come, as appropriate, from associations, authorities (governments and the European Commission), and research bodies. The results were obtained to identify the main impact factors, including the most significant impacts linked to the phase of energy absorption during surgical procedures, different emission amounts of materials used, whether reusable or not, and CO2 emissions between the two techniques.
Therefore, our internal engineering department modeled an LCA as per the ISO 14044 Guidelines.12 We performed a “door to door” analysis, including disposal plus decontamination for reusable components of hybrid instruments. The environmental impact of instrument manufacturing was approximated using global average metalworking processes for all metal components of instruments, and injection molding processes for the plastic components of instruments. All reusable components were decontaminated and reused 15 times, with energy and material inputs for decontamination being modeled using our data extrapolated from our university department.17 Subsequently, we identified the raw material composition of both single-use and reusable instruments. Because most of the instruments utilized are composites, we weighed the plastic, metal, and composite fiber components and evaluated the CO2 emissions resulting from their production, sterilization, and disposal. For example, the production of 1 kg of steel requires 14–16 kWh of energy and a melting temperature of 1435°C. To produce 1 kg of recycled steel, only 0.8 kWh of energy is required. Additionally, recycling 1 kg of steel yields 9 kg of CO2, and stainless steel remains practically unaltered over thousands of years. We also considered and weighed all anesthesiologic materials utilized during the procedures to calculate the CO2 emissions.
The CO2 emissions from electricity usage, single-use device disposal, heating, cooling, and production were calculated considering, for each group, the mean result from our database of patients who underwent minimally invasive radical prostatectomy (Table 1) surgical procedure time, anesthesia duration, length of stay, days spent in postoperative intensive care unit, and the need for conversion to open surgery.
Table 1
Peri and post operative patients characteristics
| | Group A | Group B |
Age | | 69, 39 | 67,17 |
Total Operative Time, min | | 340,43 | 279,43 |
Anestesiological time, min | | 417,82 | 354,43 |
Hospital stay, days | | 5,39 | 5 |
Intensive Care, days | | 0,956 | 1,47 |
Hb pre-op (g/dL) | | 14,83 | 15,013 |
Hb post-op (g/dL) | | 13,42 | 13,25 |
blood transfusion, % | | 0 | 4,16 |
Positive Margins, % | | 17,36 | 36,82 |
Clavien–Dindo Classification, % | | 4,16 | 8% |
pre-operative Gleason Score | | 6,87 | 7,08 |
post-opoperative GLeason score | | 7,04 | 7,3 |
Lymphnode involvement, % | | 15 | 18 |
For each procedure, we reported the disposable material and amount of CO2 used, and the quantity of fluids infused and dispersed. Furthermore, all disposable materials were weighed, and the CO2 consumption necessary for disposal was evaluated. Additionally, an estimate of the energy consumption required during the surgical procedure and hospital stay (heating and cooling) was calculated.
A standardized surgical technique was used for both the robot-assisted and laparoscopic approaches, and the procedures were performed by the same team of expert surgeons. The patient was placed in a supine position with abdominoperineal disinfection and sterile placement of an 18-ch Foley catheter. A rectal probe was inserted for the hydropneumatic rectal test at the end of procedure. We then proceeded with a supraumbilical incision and the introduction of a Verres needle for the induction of pneumoperitoneum to 12 mmHg with a standard CO2 insufflator with no AirSeal. The patient was then placed in the Trendelemburg position (25°). Two single use trocars (12 mm) and two trocars (5 mm) were used in the laparoscopic approach; four multi-use robotic trocars of 8 mm, one of 12 mm, and one of 5 mm were used in the robotic approach. A disposable single-use aspirator and multiuse forceps were used by the surgeon at the operating table during the robotic procedure. During laparoscopic procedures, a LigaSure vessel sealing system by Medtronic and a second multiuse forceps were also used. A hemostatic section of the lateral prostatic peduncles was made using medium or large hem-o-locks. Closure of the dorsal venous plexus of Santorini was made using a barbed V-Loc 3.0 suture. An endobag was used to remove the surgical specimens. Vesical-urethral anastomosis with the modified Van Velthoven technique was performed with Stratafix 3.0, and a second definitive 18-ch Foley catheter was placed in the bladder at the end of the anastomosis.