Journal of Minimal Access Surgery

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Year : 2018  |  Volume : 14  |  Issue : 4  |  Page : 316--320

Intraoperative cardiovascular response of natural orifice transluminal endoscopic surgery versus laparoscopy: A comparative animal study

Stefan Patrascu1, Catalin Andu Copaescu2, Valeriu Surlin1, Sandu Ramboiu1, Alice Nicoleta Dragoescu3, Sorin Stanilescu4, Dan Cristian4, Bogdan Silviu Ungureanu5, Daniela Elena Burtea5, Ana Maria Patrascu6, Florin Turcu2, Adrian Saftoiu5,  
1 Department of Surgery, University of Medicine and Pharmacy of Craiova, Craiova, Romania
2 Center of Excellence in Bariatric and Metabolic Surgery, Regina Maria Ponderas Academic Hospital, Bucharest, Romania
3 Department of Anesthesiology, University of Medicine and Pharmacy of Craiova, Craiova, Romania
4 Department of Surgery, Coltea Hospital, Bucharest, Romania
5 Department of Research Center in Gastroenterology and Hepatology, University of Medicine and Pharmacy of Craiova, Craiova, Romania
6 Department of Hematology, University of Medicine and Pharmacy of Craiova, Craiova, Romania

Correspondence Address:
Dr. Valeriu Surlin
Department of Surgery, University of Medicine and Pharmacy of Craiova, 1 Tabaci Street, Craiova 200642


Background: Natural orifice transluminal endoscopic surgery (NOTES) emerged as a new alternative method in minimally invasive techniques. Although a very small number of studies have compared the physiologic response in NOTES to laparoscopy, the results remain controversial. Aim: This experimental animal study aims to evaluate the intraoperative cardiovascular and respiratory effects of pure transluminal natural orifice surgery and conventional laparoscopy. Materials and Methods: Twenty female pigs (Sus scrofa domesticus) equally divided into two study groups were assigned to either pure natural orifice transluminal endoscopic techniques (Group 1) or conventional laparoscopic surgery (Group 2) and monitored intraoperatively in terms of heart rate (HR), systolic blood pressure (SBP) and O2saturation (SpO2) for 1 h. Both groups underwent simple surgical procedures such as gastrojejunostomy, oophorectomy and adnexectomy. Results: All procedures were successfully completed. The findings indicated statistically significant differences between SBP (P = 0.0065) and SpO2(P = 0.027) in the two groups at the beginning of the interventions. HR showed significant differences during the last 20 min of the interventions (min 40 and 45; P < 0.001). For the whole procedure (from the beginning of the intervention to 60 min interval), HR, SBP and SpO2values showed no statistical difference. Conclusions: Although significant differences in terms of HR, mean blood pressure and SpO2were noted at specific intervals during surgery, no real variance of the cardiovascular parameters was observed when considering the entire procedure. Therefore, NOTES seems to be a safe approach with minimally intraoperative cardiovascular and respiratory implications.

How to cite this article:
Patrascu S, Copaescu CA, Surlin V, Ramboiu S, Dragoescu AN, Stanilescu S, Cristian D, Ungureanu BS, Burtea DE, Patrascu AM, Turcu F, Saftoiu A. Intraoperative cardiovascular response of natural orifice transluminal endoscopic surgery versus laparoscopy: A comparative animal study.J Min Access Surg 2018;14:316-320

How to cite this URL:
Patrascu S, Copaescu CA, Surlin V, Ramboiu S, Dragoescu AN, Stanilescu S, Cristian D, Ungureanu BS, Burtea DE, Patrascu AM, Turcu F, Saftoiu A. Intraoperative cardiovascular response of natural orifice transluminal endoscopic surgery versus laparoscopy: A comparative animal study. J Min Access Surg [serial online] 2018 [cited 2021 Dec 7 ];14:316-320
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It was the beginning of the 20th century when a German surgeon G. Kelling presented the ‘koelioskopie’ (September 1901), thus introducing a new technique of surgical access. At the beginning of the 21st century, two revolutionary concepts can change the face of surgery: robotic and natural orifice transluminal endoscopic surgery (NOTES). NOTES, or the ‘no-scar surgery’ as it is widely known, comes as a new minimally invasive alternative to the conventional techniques, offering evident aesthetic benefits and a supposedly less physiopathological impact. However, all minimally invasive surgical techniques are proved to put up a significant burden for the cardiovascular and respiratory system, especially during the intraoperative phase.

The feasibility of this type of approach has been tested on an animal model with positive results, but the complications rate and physiologic benefits have not been properly established yet.[1],[2],[3],[4],[5] For example, one essential aspect in NOTES research that has been largely ignored before the widespread introduction of this type of approach in the clinical setting was the perioperative cardiorespiratory response. For a technique that aims to become an even less invasive than laparoscopy and its derivatives (mini-laparoscopy, single-incision laparoscopy, and so on), it is tremendously important to reduce the repercussions of surgical trauma and anaesthesia. Till date, there are only very few studies assessing the cardiovascular and respiratory parameters for the endoscopic transluminal approach.

The aim of this study is to evaluate and compare the intraoperative cardiopulmonary effects during pure natural orifice surgery and conventional laparoscopy.

 Materials and Methods

Experimental model

This was a prospective experimental study in which the perioperative cardiorespiratory parameters were evaluated. Twenty female pigs (Sus scrofa domesticus), weighed 20–35 kg, were divided into two groups: first group consisting of 10 animals underwent laparoscopic adnexectomy and the second study group was assigned to pure transgastric NOTES procedures (gastrojejunostomy and adnexectomy). The protocol was in accordance with national legislation and European directives (2010/63/EU) for animal use and care and was approved by the Craiova Medical University Animal Care and Use Institutional Review Board. All the endoscopic procedures were performed by a team comprising interventional endoscopists and surgeons assisted by a veterinary technician. The laparoscopic procedures were performed by a team of experienced laparoscopic surgeons and endoscopists.

Pre-operative care and anaesthesia

Five days before the planned procedure, the animals were quarantined in the Animal Facility of the University of Medicine and Pharmacy of Craiova, under controlled temperature (22°C–24°C), humidity (45%–55%) and 12 h dark-light cycles. Three days later, the animals were removed from woodchip bedding to prevent gastric phytobezoars and were placed into separate stalls. One day before surgery, animals were excluded from solid food with a 6 h restriction from liquids. One hour before the intervention, after intramuscular sedation, the animals were transferred to the operating room. A single dose of intravenous antibiotics (ceftriaxone; Cefort®, fluid 1 g, Antibiotice S A., Iasi, Romania) was administered at the beginning of the intervention.

The anaesthetic protocol closely followed the one used in our previous studies.[5] Induction was performed with propofol 3–5 mg/kgc, by a peripheral venous catheter 18G–20G at the marginal vein of the ear. Orotracheal intubation was achieved with a 7 mm endotracheal tube with simple lumen (MedicalExpand, France), the animal placed in dorsal decubitus for intervention. Anaesthesia was maintained using propofol 0.5 ml/kg/h in continuous perfusion, fentanyl 3 μg/kg in bolus every 45 min and pavulon 0.1 ml/kg in normal saline solution. After orotracheal intubation, the swine were kept on a semi-open circuit inhalation of 1%–3% isoflurane. The intraoperative intravenous fluids administration was maintained constant at 10 ml/kg/h. In all cases, normal saline solution was used. Respiratory rate was maintained constant at 12/min.

Surgical interventions

For the laparoscopic group, retrograde adnexectomy using a conventional technique was performed in all 10 animals. Capnoperitoneum was maintained by controlled automatic insufflation set at 11–12 mmHg.

For the transgastric endoscopic procedures, the following procedure was used for access into the peritoneal cavity after a normal esogastroscopy performed to evaluate the integrity of the stomach, and to find an adequate puncture site, the anterior gastric wall was punctured with the needle knife (Wilson-Cook Medical Inc., Limerick, Ireland). The guidewire (Wilson-Cook Medical) was inserted, followed by the endoscopic balloon dilation. The creation of pneumoperitoneum was achieved by endoscopic insufflation. The interventions consisted of simple NOTES procedures, such as transgastric adnexectomy and gastrojejunostomy performed in a pure NOTES fashion, with no additional laparoscopic trocars placed [Figure 1]. Exploration of the peritoneal cavity and the exposure was achieved by alternately placing the operating table at various angles of tilt, Trendelenburg or anti-Trendelenburg positions, as well as using the endoscopic biopsy forceps to manipulate the small bowel. For the achievement of the gastroenterostomy, we have identified a small bowel loop, which we pulled through the gastric orifice inside the stomach. We punctured it under direct vision and then we introduced the distal part of a fully covered self-expanding metallic stent, released the bowel loop and deployed the proximal part of the stent inside the stomach. For the adnexectomy, a monofilament polypectomy snare (SnareMaster™, Olympus EndoTherapy, Tokyo, Japan) achieved both hemostasis and resection of the fallopian tube and ovary. At the end of the procedure, the peritoneal gas was suctioned, the endoscope was withdrawn and the access site was either closed with OTSC™ clips (OTSC; Ovesco Endoscopy GmbH, Tubingen, Germany) or left open.{Figure 1}

Intraoperative monitoring and data collection

The cardiorespiratory parameters (pulse, O2 saturation [SpO2] and systolic blood pressure [SBP]) were automatically registered on a multiparameter monitor every 5 min since the start of the operations, for 1 h time interval (the average time needed for the laparoscopic interventions to be completed). The sensor pulse oximeter was placed on the animal's right earlobe. The data were collected and transcripted on a personal computer for later statistical analysis. Data were statistically compared using Student's t-test and Cox regression test to identify correlations between the two groups. Data analysis was performed using Office Excel Data Analysis module along with XLSTAT suite (Microsoft Corp, USA). The study was approved by Craiova Medical University Institutional Animal Care and Use Committee.


All 20 procedures were successfully performed as planned, with no major intraoperative incidents. Two animals which underwent NOTES procedures were sacrificed at the end of the procedure. Necropsy discovered no peritoneal lesions or signs of haemorrhage. The other animals had post-operative monitoring for up to 14 days.

The main morphometric characteristics of the animals were as follows: mean weight in NOTES group was 29.7 kg (variance 10.67) and 30.4 kg (variance 10.2) in laparoscopic group. Mean length in the NOTES group was 85.1 cm (variance 20.1) and 83.1 cm (variance 18.54) in the laparoscopic group. No statistically significant differences were found between groups in neither case.

During the first 5 min of the NOTES intervention, a 30° head-up position was necessary to safely perform the anterior gastric wall puncture, followed by a 30° Trendelenburg for the rest of the procedure. For the laparoscopic group, the 30° Trendelenburg position was used for the entire duration of the intervention.

During the induction of anaesthesia, before the initiation of the intervention, the comparison between mean values for SBP, heart rate (HR) and SpO2 indicated no statistical difference in the two groups.

When referring to the entire 60 min interval, no statistical difference concerning SBP was discovered between the two groups. In the detailed analysis of the parameters at the beginning of the intervention ( first 5 min interval), the SBP in the NOTES group proved significantly higher than for the laparoscopic group (mean ± standard deviation for laparoscopic group = 128.6 ± 8.72 and for NOTES = 155.7 ± 24.09; P = 0.00653) [Figure 2]. For the individual analysis in the NOTES group due to the large variance encountered herein, we removed one animal showing SBP of 221 mmHg. When these data were removed from our analysis, no significant difference was encountered. For the following recorded intervals, the difference was insignificant (P > 0.05). The mean SBP in the first 30 min of the intervention was 143.6 mmHg (variance = 15.3 mmHg) as for the last 30 min interval it indicated an average of 134.1 mmHg (variance = 36.4 mmHg), thus pointing a significant decrease (P = 0.0026). These findings contrasted with those for laparoscopy which followed an inverse, ascending trend. During the procedures, no optimisation of the intravenous fluid infusion for the blood pressure and urinary output was considered necessary in neither group.{Figure 2}

Next parameter followed was the HR. For the NOTES group, data analysis showed an important increase in mean HR during the 40–45 min interval compared to laparoscopy (P < 0.001) [Figure 3]. Similarly to the SBP when considered the extended 60 min period, HR proved no significant difference between laparoscopic and NOTES groups.{Figure 3}

The average SpO2 in the transluminal group was 99.06% (±0.3), similar to laparoscopy (99.2 ± 0.19) (P > 0.05) [Figure 4]. No difference in SpO2 was found whatsoever between the groups neither during the overall procedure nor at the beginning or the end of monitoring.{Figure 4}


Since the first documentation of a transluminal endoscopic procedure by Anthony Kalloo, in 2004, the surgical world witnessed a rapid evolution of this method.[1] Starting from simple procedures, such as liver biopsies and fallopian tube ligation to transluminal ventral hernia repair, nephrectomies or different types of colectomies, increasingly complex procedures were reported each year.[2],[3],[4],[5]

Due to the overall positive response regarding the transluminal endoscopic surgery in 2005, the Society of American Gastrointestinal Endoscopic Surgeons and the American Society for Gastrointestinal Endoscopy established a joint committee to support the research, education and to create a common registry for human NOTES procedures. The result of this collaboration was a fundamental document called the white paper which settled the future directions of development in this innovative field.[6] One of the aspects taken into account was the biologic response related to transluminal procedures. In reply, a modest number of studies concerning mostly the immunologic response as well as the intraperitoneal pressure fluctuations were published, with even fewer reports submitted on cardiovascular effects during NOTES.[7],[8],[9]

This study, centred on the evaluation of the three most commonly monitored cardiovascular parameters in the operative settings, comes as a response to this major drawback. Our results have clearly proven that NOTES is not associated with major intraoperative alterations in the hemodynamic status when compared with laparoscopy in any of the parameters taken into account (HR, SBP and SpO2). Still, an interesting aspect found in the NOTES group was the association between a significant decrease in SBP from the start of the intervention and the progressive decrease in HR.

Our study has several potential limitations, also found in the other papers focusing on this aspect: type of insufflation used, small number of subjects and experimental setting in itself. Although swine shares many similarities with humans, there are unarguably some differences in terms of hemodynamic and respiratory pathophysiologic response between the two species. However, the swine has been shown to be the best substitute in experimental surgery preceding the clinical settings, as well as for medicine and biomedical technology as a whole.[10],[11] Another limitation is the different types of insufflation used in the laparoscopic and NOTES groups. The lack of dedicated endoscopic platforms is a major drawback for the introduction of NOTES, a fact already acknowledged in the NOTES white paper.[6] It is known that current endoscopes are not designed for transluminal interventions; thus, no automatic insufflation system was considered necessary for these endoscopes. Furthermore, one of the best indications for NOTES is the small, time sparing, simple procedures. Until dedicated endoscopic platforms are available, these particular types of short NOTES interventions might not require automatic insufflation. Despite this drawback, the only aspect worth mentioning in the NOTES group was the association between a significant decrease in SBP from the start of the intervention and the progressive decrease in HR. A viable explanation for this aspect could be the progressive increase of the intraperitoneal pressure in the later phases of the intervention when a better visualisation was required.

The main aspect highlighted in this study is that the hemodynamic response in minimally invasive surgery, whether we are referring to conventional laparoscopy or NOTES, is probably not dependent on the type of access used (transabdominal or transgastric). However, despite the growing number of studies of NOTES procedures on human patients,[12],[13],[14],[15],[16] there is still a great concern regarding the safety and the invasiveness of this technique.[17] The need for more research on these aspects is mandatory before the widespread clinical use of NOTES.


Although statistically significant differences between laparoscopic and NOTES groups in terms of HR, mean blood pressure and SpO2 pointed at specific time intervals were observed, no variance of the hemodynamic parameters was noticed when analysing the entire procedure. Our results show that NOTES, at this current stage of development, is a safe technique, with low untoward cardiovascular implications.


The study was financed from two research grants: ‘Survival and immunologic impact of transgastric endoscopic oophorectomy compared to laparoscopy’, (RO NOTES) UEFISCDI PNII- Partnership Grant no 41023/11.10.2007, and ‘Gastrointestinal by-pass for obesity and type II diabetes mellitus based upon miminal invasive endoscopic procedures’, UEFISCDI PN II Partnership Grant no PN-II-PT-PCCA-2013-4-1257 (GEMINI).

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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