Materials and methods
HEAT, PNEUMOPERITONEUM
This prospective, single-center clinical trial has been reported according to the STROBE guidelinesThe inclusion criteria for the SARS-CoV-2 group was positive SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) of nasopharyngeal swabs and the indication for open or MIS procedure. The control group included patients with negative nasopharyngeal SARS-CoV-2 RT-PCR tests undergoing elective open or MIS abdominal procedures. If the patients had multiple nasopharyngeal swabs during the hospital stay, the latest one before surgery was considered for inclusion in the study. Informed consent was obtained from all included patients or their legal guardians.The following samples were collected in both groups during the surgery: nasopharyngeal and intraabdominal swabs, blood, urine, stool, surgical smoke for 30 min after starting electrocauterization, heat, and moisture (HME) filter membrane from the mechanical ventilation, and air samples from the operating room (OR) for 30 min at the approximate end of surgery.The surgical smoke samples from the pneumoperitoneum during MIS and the approximate surgical field during open surgery and air samples from the OR were collected in 15 ml of sterilized phosphate-buffered saline (PBS) solution using an SKC BioSampler. The SKC BioSampler is a highly efficient gas collection device with a high-volume sonic pump used to analyze airborne microorganismsOn the left: SKC BioSampler attached to connecting tubes to the patient side and the vacuum pump: a: SKC BioSampler; b, c, f: connecting tubes; d: 3-way stopcock with a tube; e: 5 mm trocar. On the right: SKC Bio Sampler disassembled.Collecting the surgical smoke with SKC BioSampler in MIS (upper left corner) and open (lower left corner) surgery.The samples were processed and screened for SARS-CoV-2 RNA in a certified clinical virology laboratory. The RNA was extracted with automated commercial magnetic bead-based procedures using QIASymphony and the DSP Virus/Pathogen Mini Kit (QIAGEN, Hilden, Germany) or chemagic 360 and the Viral DNA/RNA 300 Kit H96 (PerkinElmer, Rodgau, Germany) complying with the manufacturer's instructions. The extracted RNA was tested for SARS-COV-2 RNA with a commercial dual-target (E&N gene) RT-qPCR-Assay (TIB MOLBIOL, Berlin, Germany) employing a Roche LightCycler I or II. Some nasopharyngeal swabs were also tested with a commercial SARS-CoV-2 RT-PCR assay on the fully automated Roche Cobas 6800 instrument (Roche Diagnostics, Germany). The positive surgical smoke samples were to be sent to the appropriate laboratory for growth culture analysis to test for potential infectivity.