Randomized blinded trial comparing the cardiopulmonary effects of NOTES with standard laparoscopy in a porcine survival model

Background: Anecdotal reports of natural orifice translumenal endoscopic surgery (NOTES) procedures in patients are emerging. Whether the new procedure is truly less invasive is not known. We compared perioperative cardiopulmonary parameters during NOTES with standard laparoscopy. Methods: Twelve swine were randomized to transgastric peritoneoscopy with air or diagnostic laparoscopy with CO₂. Cardiopulmonary parameters were invasively monitored. Animals were survived for 14 days. Data were analyzed by an investigator blinded to the procedure performed. Treatments were contrasted on the mean outcome using a repeated measures linear model. Results: All experiments were successfully completed. No gastric leak or peritonitis resulted. Two hundred and fifty cubic centimeters of saline irrigation was adequate to decrease gastric contamination. Respiratory compromise requiring desufflation resulted in two laparoscopy and one endoscopy animal. Mean arterial oxygen saturation remained at baseline for the NOTES group and decreased by 1.5 ± 1.5% in the laparoscopic group (p < 0.001). Mean arterial pH dropped significantly lower in the laparoscopy versus the NOTES group (-0.09 ± 0.06 versus -0.05 ± 0.05, p = 0.01). Mean systolic blood pressure (Sbp) in both groups remained unchanged from the respective baseline (p = 0.45). Mean diastolic blood pressure (Dbp) showed a mean difference of 19 ± 1.5 mmHg between the groups (p < 0.001), increasing from baseline for the laparoscopy group and decreasing significantly from baseline in the NOTES group (+2.4 ± 12.5 versus -6.1 ± 7.0 mmHg, p < 0.001). Mean heart rate increased significantly from baseline in the laparoscopy group compared to the NOTES group (15.0 ± 23.4 versus 3.8 ± 19.0 bpm, p = 0.004). A widening pulse pressure resulted in the NOTES group compared to the laparoscopy group (p < 0.001). The mean bladder pressure was 14.6 ± 8.0 cmH₂O in the laparoscopy group compared to 7.1 ± 7.1 cm H₂O the NOTES group (p < 0.001). Conclusion: Significant differences in measured but not clinically apparent cardiopulmonary parameters were encountered. The difference in insufflation gas, different vagal or catecholamine response may be contributing to these findings.