Robotic liver resection: initial experience with three-arm robotic and single-port robotic technique

Robotic Liver Resection for Hepatocellular Carcinoma: A Multicenter Case Series

BACKGROUND

Liver resection is the standard treatment for resectable hepatocellular carcinoma (HCC). The advent of robotic surgery has extended its application in liver surgery, reducing post-operative complications without compromising oncological safety. This study is a retrospective series with the aim of analyzing the preoperative patient's and tumor's characteristics and evaluating intraoperative and post-operative data in terms of hospital stay, complications, and oncological radicality.

METHODS

Data were collected from a multicenter retrospective database that includes 1070 consecutive robotic liver resections (RLRs) performed in nine European hospital centers from 2011 to 2023. Of the entire series, 343 liver resections were performed for HCC.

RESULTS

A total of 247 patients (72.3%) had mono-focal lesions. Major hepatectomies and anatomical resections have been perfomed in 87% and 55% of patients, respectively. All 17 conversions (4.95%) were to the open approach. The operative mean time was 239.56 min and the estimated blood loss was 229.45 mL. The overall post-operative complication rate was 22.74%, but severe complications occurred in 4.08% of patients and one of them (0.29%) was reoperated on. The mean hospital stay was 5.82 days with a mean ICU stay of 0.9 days. Twenty-six resections (7.6%) were R1 parenchymal. Forty-six patients (4.08%) were readmitted to the hospital within 90 days after discharge and seventy-eight patients (22.74%) had disease recurrence. Total deaths included 36 (10.5%) patients with a 90-day mortality of 0.9%.

CONCLUSIONS

Robotic liver resection for HCC is feasible and safe when performed in experienced centers by surgeons who have completed the learning curve.

The Current Role of Single-Site Robotic Approach in Liver Resection: A Systematic Review

BACKGROUND

Liver resection is a critical surgical procedure for treating various hepatic pathologies. Minimally invasive approaches have gradually gained importance, and, in recent years, the introduction of robotic surgery has transformed the surgical landscape, providing potential advantages such as enhanced precision and stable ergonomic vision. Among robotic techniques, the single-site approach has garnered increasing attention due to its potential to minimize surgical trauma and improve cosmetic outcomes. However, the full extent of its utility and efficacy in liver resection has yet to be thoroughly explored.

METHODS

We conducted a comprehensive systematic review to evaluate the current role of the single-site robotic approach in liver resection. A detailed search of PubMed was performed to identify relevant studies published up to January 2024. Eligible studies were critically appraised, and data concerning surgical outcomes, perioperative parameters, and post-operative complications were extracted and analyzed.

RESULTS

Our review synthesizes evidence from six studies, encompassing a total of seven cases undergoing robotic single-site hepatic resection (SSHR) using various versions of the da Vinci© system. Specifically, the procedures included five left lateral segmentectomy, one right hepatectomy, and one caudate lobe resection. We provide a summary of the surgical techniques, indications, selection criteria, and outcomes associated with this approach.

CONCLUSION

The single-site robotic approach represents an option among the minimally invasive approaches in liver surgery. However, although the feasibility has been demonstrated, further studies are needed to elucidate its optimal utilization, long-term outcomes, and comparative effectiveness against the other techniques. This systematic review provides valuable insights into the current state of single-site robotic liver resection and underscores the need for continued research in this rapidly evolving field.

Automatic patient positioning based on robot rotational workspace for extended reality

PURPOSE

Understanding the properties and aspects of the robotic system is essential to a successful medical intervention, as different capabilities and limits characterize each. Robot positioning is a crucial step in the surgical setup that ensures proper reachability to the desired port locations and facilitates docking procedures. This very demanding task requires much experience to master, especially with multiple trocars, increasing the barrier of entry for surgeons in training.

METHODS

Previously, we demonstrated an Augmented Reality-based system to visualize the rotational workspace of the robotic system and proved it helps the surgical staff to optimize patient positioning for single-port interventions. In this work, we implemented a new algorithm to allow for an automatic, real-time robotic arm positioning for multiple ports.

RESULTS

Our system, based on the rotational workspace data of the robotic arm and the set of trocar locations, can calculate the optimal position of the robotic arm in milliseconds for the positional and in seconds for the rotational workspace in virtual and augmented reality setups.

CONCLUSIONS

Following the previous work, we extended our system to support multiple ports to cover a broader range of surgical procedures and introduced the automatic positioning component. Our solution can decrease the surgical setup time and eliminate the need to repositioning the robot mid-procedure and is suitable both for the preoperative planning step using VR and in the operating room-running on an AR headset.

Laparoscopic and Robot-Assisted Hepatic Surgery: An Historical Review

Hepatic surgery is a rapidly expanding component of abdominal surgery and is performed for a wide range of indications. The introduction of laparoscopic cholecystectomy in 1987 was a major change in abdominal surgery. Laparoscopic surgery was widely and rapidly adopted throughout the world for cholecystectomy initially and then applied to a variety of other procedures. Laparoscopic surgery became regularly applied to hepatic surgery, including segmental and major resections as well as organ donation. Many operations progressed from open surgery to laparoscopy to robot-assisted surgery, including colon resection, pancreatectomy, splenectomy thyroidectomy, adrenalectomy, prostatectomy, gastrectomy, and others. It is difficult to prove a data-based benefit using robot-assisted surgery, although laparoscopic and robot-assisted surgery of the liver are not inferior regarding major outcomes. When laparoscopic surgery initially became popular, many had concerns about its use to treat malignancies. Robot-assisted surgery is being used to treat a variety of benign and malignant conditions, and studies have shown no deterioration in outcomes. Robot-assisted surgery for the treatment of malignancies has become accepted and is now being used at more centers. The outcomes after robot-assisted surgery depend on its use at specialized centers, the surgeon's personal experience backed up by extensive training and maintenance of international registries. Robot-assisted hepatic surgery has been shown to be associated with slightly less intraoperative blood loss and shorter hospital lengths of stay compared to open surgery. Oncologic outcomes have been maintained, and some studies show higher rates of R0 resections. Patients who need surgery for liver lesions should identify a surgeon they trust and should not be concerned with the specific operative approach used. The growth of robot-assisted surgery of the liver has occurred in a stepwise approach which is very different from the frenzy that was seen with the introduction of laparoscopic cholecystectomy. This approach allowed the identification of areas for improvement, many of which are at the nexus of engineering and medicine. Further improvements in robot-assisted surgery depend on the combined efforts of engineers and surgeons.

Evaluation of the learning curve and safety outcomes in robotic assisted vaginal natural orifice transluminal endoscopic hysterectomy: A case series of 84 patients

BACKGROUND

To explore the learning curve and safety outcomes of robotic assisted transvaginal natural orifice transluminal endoscopic surgery (R-vNOTES) for hysterectomy in benign gynaecological diseases.

METHODS

A retrospective chart review of all patients undergoing R-vNOTES hysterectomy for benign gynaecological disease from 2019 to 2021.

SETTING

An academic tertiary care university hospital in Houston, TX, USA.

RESULTS

84 patients were identified that met the study requirements. The mean hysterectomy time was 77.27 ± 2.89 min. The median additional operation time was 63 (8-206) min. There were two conversions to robotic assisted single incision laparoscopy. Thirteen (15.48%) patients had an associated complication. Analysis of the learning curve suggests plateauing of hysterectomy time at approximately 10 cases and time for robot docking and port placement after 10-20 cases.

CONCLUSION

R-vNOTES is a safe and effective route for hysterectomy. For a surgeon with experience in laparoscopic single site surgery and abdominal robotic surgery, they need to perform 10 cases of R-vNOTES hysterectomy and 10-20 cases in port placement and robotic docking to achieve proficiency.

The impact of robotics in liver surgery: A worldwide systematic review and short-term outcomes meta-analysis on 2,728 cases

BACKGROUND

The dissemination of robotic liver surgery is slow-paced and must face the obstacle of demonstrating advantages over open and laparoscopic (LLS) approaches. Our objective was to show the current position of robotic liver surgery (RLS) worldwide and to identify if improved short-term outcomes are observed, including secondary meta-analyses for type of resection, etiology, and cost analysis.

METHODS

A PRISMA-based systematic review was performed to identify manuscripts comparing RLS vs open or LLS approaches. Quality analysis was performed using the Newcatle-Ottawa score. Statistical analysis was performed after heterogeneity test and fixed- or random-effect models were chosen accordingly.

RESULTS

After removing duplications, 2728 RLS cases were identified from the final set of 150 manuscripts. More than 75% of the cases have been performed on malignancies. Meta-analysis from the 38 comparative reports showed that RLS may offer improved short-term outcomes compared to open procedures in most of the variables screened. Compared to LLS, some advantages may be observed in favour of RLS for major resections in terms of operative time, hospital stay and rate of complications. Cost analyses showed an increased cost per procedure of around US$5000.

CONCLUSIONS

The advantages of RLS still need to be demonstrated although early results are promising. Advantages vs open approach are demonstrated. Compared to laparoscopic surgery, minor perioperative advantages may be observed for major resections although cost analyses are still unfavorable to the robotic approach.

The Use of Robotics in Surgery of Benign Liver Diseases: A Systematic Review

BACKGROUND

Surgical treatment of benign liver diseases (BLD) remains a field of conflict, due to increased risk and high complication rate. However, the introduction of minimally invasive surgery has led to increased number of patients with BLD being treated surgically, with similar outcomes and fewer complications. Current data support the application of laparoscopic surgery (LS) and robotic surgery (RS) in surgical treatment of liver malignancies, but there are insufficient data concerning the application of robotic surgery in BLD. In the present systematic review, we aimed to evaluate the application of RS in BLD surgery.

METHODS

After a thorough search of Medline, Scopus, and Cochrane Library, 12 studies were considered eligible with a total number of 115 patients with BLD.

DISCUSSION

In brief, RS appears to be a safe and feasible option for BLD surgery. When compared to open surgery, RS is associated with lower blood loss, shorter length of stay, and fewer complication rate. Regarding LS, the peri- and postoperative outcomes were similar, but RS can overcome the technical limitations of LS. However, the cost of RS remains a major drawback in its widespread application.

CONCLUSIONS

Considering our findings, RS can be a safe and feasible option for BLD surgery, but further studies are needed to justify the introduction of RS in liver surgery and to define the type of patients that will benefit the most from it.

Robotic Surgery for Malignant Liver Disease: a Systematic Review of Oncological and Surgical Outcomes

Robot-assisted laparoscopic surgery is yet another modification of minimally invasive liver surgery. It is described as feasible and safe from the surgical point of view; however, oncological outcomes need to be adequately analysed to justify the use of this technique when resecting malignant liver tumours. We reviewed existing English medical literature on robot-assisted laparoscopic liver surgery. We analysed surgical outcomes and oncological outcomes. We analysed operative parameters including operative time, type of hepatectomy, blood loss, conversion rate, morbidity and mortality rates and length of stay. We also analysed oncological outcomes including completeness of resection (R status), recurrence, survival and follow-up data. A total of 582 patients undergoing robot-assisted laparoscopic liver surgery were analysed from 17 eligible publications. Only 5 publications reported survival data. The overall morbidity was 19% with 0.2% reported mortality. R0 resection was achieved in 96% of patients. Robotic liver surgery is feasible and safe with acceptable morbidity and oncological outcomes including resection margins. However, well-designed trials are required to provide evidence in terms of survival and disease-free intervals when performed for malignancy.

Reasons for open conversion in robotic liver surgery: A systematic review with pooled analysis of more than 1000 patients

BACKGROUND

Conversion to open during minimally invasive liver resection has a high rate. To identify the reasons to convert could help in defining a strategy to decrease the event "conversion."

METHODS

A systematic review has been performed. Our large series of robotic hepatic resections were analyzed and included in the review.

RESULTS

Fifty papers were selected and carefully evaluated in full text. Twenty-nine were ultimately used for analysis, including all published robotic liver resections. Our series included 11 conversions out of 139 patients (7.9%). Adhesions were not a declared reason to convert. The robotic approach still had a high percentage of open conversions because of difficulties in assessing the tumor margin.

CONCLUSIONS

Causes for conversion were carefully analyzed and compared with what previously described for the pure laparoscopic approach. This could be crucial in defining how to improve the performance and minimize the conversion rate.

International consensus statement on robotic hepatectomy surgery in 2018

The robotic surgical system has been applied in liver surgery. However, controversies concerns exist regarding a variety of factors including the safety, feasibility, efficacy, and cost-effectiveness of robotic surgery. To promote the development of robotic hepatectomy, this study aimed to evaluate the current status of robotic hepatectomy and provide sixty experts’ consensus and recommendations to promote its development. Based on the World Health Organization Handbook for Guideline Development, a Consensus Steering Group and a Consensus Development Group were established to determine the topics, prepare evidence-based documents, and generate recommendations. The GRADE Grid method and Delphi vote were used to formulate the recommendations. A total of 22 topics were prepared analyzed and widely discussed during the 4 meetings. Based on the published articles and expert panel opinion, 7 recommendations were generated by the GRADE method using an evidence-based method, which focused on the safety, feasibility, indication, techniques and cost-effectiveness of hepatectomy. Given that the current evidences were low to very low as evaluated by the GRADE method, further randomized-controlled trials are needed in the future to validate these recommendations.

Robotic Developments in Cancer Surgery

Indications for robotic surgery have been rapidly expanding since the first introduction of the robotic surgical system in the US market in 2000. As the robotic systems have become more sophisticated over the past decades, there has been an expansion in indications. Many new tools have been added with the aim of optimizing outcomes after oncologic surgery. Complex abdominal cancers are increasingly operated on using robot-assisted laparoscopy and with acceptable outcomes. In this article, the authors discuss robotic developments, from the past and the future, with an emphasis on cancer surgery.

Safety and oncologic outcomes of robotic liver resections: A systematic review

The robotic system has emerged as a new minimally invasive technology with promising results. We sought to systematically review the available literature on the safety and the oncologic outcomes of robotic liver surgery. A systematic review was conducted using Medline (PubMed), Embase and Cochrane library through November 12th, 2017. A robotic approach may be a safe and feasible surgical option for minor and major liver resections.

Selecting incision-dominant cases for robotic liver resection: towards outpatient hepatectomy with rapid recovery

Background

The premise of minimally invasive surgery (MIS) is to minimize facial and muscle injury in order to enhance recovery from surgery. Robotic MIS surgery for resection of tumors in solid organs is gaining traction, though clear superiority of this approach is lacking and robotic surgery is more expensive. Our philosophy in robotically-assisted hepatectomy has been to employ this approach for cases where location of tumors make difficult a classical laparoscopic approach (superior/posterior tumors), and cases where the incision for an open operation dominates the course of recovery.

Methods

This is a retrospective review of a prospectively collected database.

Results

In this study we report 97 cases of liver resection subjected to the robotic approach, of which 90% were resected robotically. The mean operative time was 186±9 min; mean blood loss was 111±15 mL, and complications occurred in 9%. Two thirds of the patients remained in hospital 3 days or less, including three patients subjected to hemihepatectomy (2 left and 1 right). Fourteen individuals were discharged on the same day. The strongest predictors of long hospital stay (>3 days) were major hepatectomy (P=0.007), complications (P=0.008), and operative time >210 min (P=0.001).

Conclusions

With thoughtful case selection, this is a first demonstration that hepatectomy can be conducted as an out-patient or short-stay procedure.

Robotic-Assisted Versus Laparoscopic Left Lateral Sectionectomy: Analysis of Surgical Outcomes and Costs by a Propensity Score Matched Cohort Study

BACKGROUND

After comparing with open approach, left lateral sectionectomy (LLS) has become standard in terms of short-term outcomes without jeopardizing long-term survival when performed for malignancy. The aim of this study was to compare the short-term and economic outcomes of laparoscopic (L-LLS) and robotic (R-LLS) LLS.

METHODS

All consecutive patients who underwent L-LLS or R-LLS from 1997 to 2014 were analyzed. Short-term and economic outcomes were compared between the two groups using a propensity score matching (PSM).

RESULTS

Ninety-six consecutive cases of LLS were performed using the laparoscopic (80 cases; 83 %) or robotic (16 cases; 17 %) approach. The two groups were similar for operative and surgical outcomes. Operation time was similar in the R-LLS compared to the L-LLS group (190 vs. 162 min; p = 0.10). Perioperative costs were higher (1457 € vs. 576 €; p < 0.0001) in the R-LLS group than in the L-LLS group; however, postoperative costs were similar between the two groups (4065 € in the R-LLS group vs. 5459 € in the L-LLS group; p = 0.30). Total costs were similar between the two groups (5522 € in the R-LLS group vs. 6035€ in the L-LLS group; p = 0.70). The PSM included 14 patients for each group. Surgical and economic outcomes remained similar after PSM, except for total operating time which was significantly longer in the R-LLS group than in the L-LLS group.

CONCLUSIONS

Even if feasible and safe, the robotic approach does not seem so far to offer additional benefit in terms of intra- and postoperative outcomes over the laparoscopic approach in patients requiring LLS. Total costs associated with the R-LLS group are not greater than that associated with the L-LLS group, which is the standard of care so far.

Laparoscopic and robotic approach for hepatocellular carcinoma-state of the art

Hepatocellular carcinoma (HCC) is the sixth most common malignant tumor worldwide and the most common primary liver cancer, in over 80% of cases HCC grown on a cirrhotic liver. Laparoscopic liver resection (LLR) is now worldwide accepted considering the excellent results shown. Minimally invasive surgical approach for HCC is increasing continuously and in specialized centers seems to become the first-line approach for those patients. The aim of this review presents and discusses state of the art in the laparoscopic and robotic surgical treatment of HCC. An electronic search was performed to identify all studies dealing with HCC resected with laparoscopy or robotic approach. Indications for laparoscopic resection, robotic assisted and totally robotic resection of HCC will be doubtless increased in future years. LLR and robotic approach for HCC is safe and feasible.

Application of stapling devices in liver surgery: Current status and future prospects

The liver is a vascular-rich solid organ. Safe and effective dissection of the vessels and liver parenchyma, and control of intraoperative bleeding are the main concerns when performing liver resection. Several studies have confirmed that intraoperative blood loss and postoperative transfusion are predictors of postoperative morbidity and mortality in liver surgery. Various methods and instruments have been developed during hepatectomy. Stapling devices are crucial for safe and rapid anastomosis. They are used to divide hepatic veins and portal branches, and to transect liver parenchyma in open liver resection. In recent years, laparoscopic liver surgery has developed rapidly, and is now preferred by many surgeons. Stapling devices have also been gradually introduced in laparoscopic liver surgery, from dividing vascular and biliary structures to parenchymal transection. This may be because staplers make manipulation more simple, rapid and safe. Even in single incision laparoscopic surgery, which is recognized as a new minimally invasive technique, staplers are also utilized, especially in left lateral hepatectomy. For safe application of stapling devices in liver surgery, more related designs and modifications, such as application of a suitable laparoscopic articulating liver tissue crushing device, a staple line reinforcement technique with the absorbable polymer membrane or radiofrequency ablation assistance, are still needed. More randomized studies are needed to demonstrate the benefits and find broader indications for the use of stapling devices, to help expand their application in liver surgery.

Robot-assisted laparoscopic liver resection: a systematic review and pooled analysis of minor and major hepatectomies

BACKGROUND

Robotic surgery has been introduced to overcome the limitations of conventional laparoscopy. A systematic review and meta-analysis were performed to assess the safety and feasibility for three subgroups of robot-assisted laparoscopic liver resection: (i) minor resections of easily accessible segments: 2/3, 4B, 5, 6, (ii) minor resections of difficult located segments: 1, 4A, 7, 8 and (iii) major resections: ≥ 4 segments.

METHODS

A systematic search was performed in PubMed, EMBASE and Cochrane Library.

RESULTS

Twelve observational, mostly retrospective studies reporting on 363 patients were included. Data were pooled and analyzed. For subgroup (i) (n = 81) the weighted mean operative time was 215 ± 65 min. One conversion (1%) to laparotomy was needed. Weighted mean operative time for subgroup (ii) (n = 17) was 220 ± 60 min. No conversions were needed. For subgroup (iii) (n = 99) the weighted mean operative time was 405 ± 100 min. In this subgroup 8 robotic procedures (8%) were converted to open surgery.

CONCLUSION

Data show that robot-assisted laparoscopic liver resection is feasible in minor resections of all segments and major resections. Larger, prospective studies are warranted to compare the possible advantages of robot-assisted surgery with conventional laparoscopy and open surgery.

A systematic review of robotic-assisted liver resection and meta-analysis of robotic versus laparoscopic hepatectomy for hepatic neoplasms

BACKGROUND

Robotic-assisted liver resection (RALR) was introduced as procedures of overcoming the limitations of traditional laparoscopic liver resection (LLR). The aim of this review was to evaluate the surgical results of RALR from all published studies and the results of comparative studies of RALR versus LLR for hepatic neoplasm.

METHODS

Eligible studies involved RALR that published between January 2001 and December 2014 were reviewed systematically. Comparisons between RALS and LLR were pooled and analyzed by meta-analytical techniques using random- or fixed-effects models, as appropriate.

RESULTS

In total, 29 studies, involving 537 patients undergoing RALR, were identified. The most common RALR procedure was a wedge resection and segmentectomy (28.67%), followed by right hepatectomy (17.88%), left lateral sectionectomy (13.22%), and bisegmentectomy (9.12%). The conversion and complication rates were 5.59 and 11.36%, respectively. The most common reasons for conversion were bleeding (46.67%) and unclear tumor margin (33.33%). Intracavitary fluid collections and bile leaks (40.98%) were the most frequently occurring morbidities. Nine studies, involving 774 patients, were included in meta-analysis. RALR had a longer operative time compared with LLR [mean difference (MD) 48.49; 95% confidence interval (CI) 22.49-74.49 min; p = 0.0003]. There were no significant differences between the two groups in blood loss [MD 31.53; 95% CI -14.74 to 77.79 mL; p = 0.18], hospital stay [MD 0.13; 95% CI -0.54 to 0.80 days; p = 0.18], postoperative overall morbidity [odds ratio (OR) 0.76; 95% CI 0.49-1.19; p = 0.23], and surgical margin status (OR 0.61; 95% CI 0.33-1.12; p = 0.11); cost was greater than robotic surgery (p = 0.001).

CONCLUSION

RALR and LLR display similar safety, feasibility, and effectiveness for hepatectomies, but further studies are needed before any final conclusion can be drawn, especially in terms of oncologic and cost-effectiveness outcomes.

Robotic liver surgery

Robotic surgery is an evolving technology that has been successfully applied to a number of surgical specialties, but its use in liver surgery has so far been limited. In this review article we discuss the challenges of minimally invasive liver surgery, the pros and cons of robotics, the evolution of medical robots, and the potentials in applying this technology to liver surgery. The current data in the literature are also presented.

[Laparoscopic liver surgery]

Liver resection remains the method of choice for curative treatment for liver tumors. Development in diagnostic and surgical techniques has improved operative results as well as long-term outcomes. In the last decade minimally invasive laparoscopic (LAP) surgery has been increasingly adopted by liver units. The trend in LAP liver resection has been moving from limited resections towards major hepatectomy. This process, however, is relatively slow, which can be due to technical difficulties of the procedure and fear of haemorrhage. Despite having a hard time at the start, major resections become more common. Up to now approximately 6000 LAP liver resections were performed worldwide, number of major hepatectomies is estimated between 700-800. LAP liver resections are feasible with significant benefits for patients consisting of less blood loss, less narcotic requirements, and shorter hospital stay with comparable postoperative morbidity and mortality to open liver resections. It is an accepted management of both benign and malignant liver lesions. There is no difference between LAP and open surgery in late survival after resection for colorectal liver metastases. Overall survival of LAP resected hepatocellular carcinoma cases seems to be superior compared with open surgery.

Single-port laparoscopic approach of the left liver: initial experience

INTRODUCTION

New technological advances have enabled the development of single-port laparoscopic surgery. This approach began with cholecystectomy and subsequently with other abdominal surgeries. However, few publications on laparoscopic liver surgery have described the use of complete single-port access. We present our initial experience of a single-port laparoscopic hepatectomy.

MATERIAL AND METHODS

Between May 2012 and December 2013, 5 single-port laparoscopic hepatectomies were performed: one for benign disease and four for colorectal liver metastases. The lesions were approached through a 3-5 cm right supraumbilical incision using a single-port access device. All the lesions were located in hepatic segments II or III. Four left lateral sectorectomies and one left hepatectomy were performed.

RESULTS

Median operative time was 135 min. No cases were converted to conventional laparoscopic or open surgery. The oral intake began at 18 h. There were no postoperative complications and no patients required blood transfusion. The median hospital stay was 3 days. The degree of satisfaction was very good in 4 cases and good in one. Patients resumed their normal daily activities at 8 days.

DISCUSSION

Single-port laparoscopic hepatectomy is safe and feasible in selected cases and may reduce surgical aggression and offer better cosmetic results. Comparative studies are needed to determine the real advantages of this approach.