| 1. |
- Cengic, Goran, 1978, et al.
(author)
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A Framework for Component Based Distributed Control Software Development Using IEC 61499
- 2006
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In: Proceedings of the 2006 IEEE International Conference on Emerging Technology and Factory Automation, Sep 2006, Prague, Czech Republic.
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Journal article (peer-reviewed)abstract
- A framework for component based distributed control software is proposed. The primary application for the framework is in distributed control systems. The framework proposes new software components, called automation components that can be hierarchically embedded to produce new components. Automation components are also combined to produce hierarchical component based applications. The framework is independent of the execution platform, however it is shown how an application that is developed using the framework can be executed using IEC 61499 platform. The validity of the framework is evaluated using an industrial example of a reconfigurable manufacturing cell.
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| 2. |
- Cengic, Goran, 1978, et al.
(author)
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Formal Modeling of Function Block Applications Running in IEC 61499 Execution Runtime
- 2006
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In: 2006 IEEE Conference on Emerging Technologies and Factory Automation, ETFA; Hamburg; Germany; 20 September 2006 through 22 September 2006. - 9781424406814 ; , s. 1269-1276
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Conference paper (peer-reviewed)abstract
- The execution model in a new standard for distributed control systems, IEC 61499, is analyzed. It is shown how the same standard compliant application running in two different standard compliant runtime environments may result in completely different behaviors. Thus, to achieve true portability of applications between multiple standard compliant runtime environments a more detailed execution model is necessary. In this paper a new runtime environment, Fuber, is presented along with a formal execution model. In this case the execution model is given as a set of interacting state machines which makes it straightforward to analyze the behavior of the application and runtime together using existing tools for formal verification.
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| 3. |
- Hedberg, Jakob, et al.
(author)
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Randomized controlled trial of nasogastric tube use after esophagectomy : study protocol for the kinetic trial
- 2024
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In: Diseases of the esophagus. - : John Wiley & Sons. - 1120-8694 .- 1442-2050. ; 37:6
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Journal article (peer-reviewed)abstract
- Esophagectomy is a complex and complication laden procedure. Despite centralization, variations in perioparative strategies reflect a paucity of evidence regarding optimal routines. The use of nasogastric (NG) tubes post esophagectomy is typically associated with significant discomfort for the patients. We hypothesize that immediate postoperative removal of the NG tube is non-inferior to current routines. All Nordic Upper Gastrointestinal Cancer centers were invited to participate in this open-label pragmatic randomized controlled trial (RCT). Inclusion criteria include resection for locally advanced esophageal cancer with gastric tube reconstruction. A pretrial survey was undertaken and was the foundation for a consensus process resulting in the Kinetic trial, an RCT allocating patients to either no use of a NG tube (intervention) or 5 days of postoperative NG tube use (control) with anastomotic leakage as primary endpoint. Secondary endpoints include pulmonary complications, overall complications, length of stay, health related quality of life. A sample size of 450 patients is planned (Kinetic trial: https://www.isrctn.com/ISRCTN39935085). Thirteen Nordic centers with a combined catchment area of 17 million inhabitants have entered the trial and ethical approval was granted in Sweden, Norway, Finland, and Denmark. All centers routinely use NG tube and all but one center use total or hybrid minimally invasive-surgical approach. Inclusion began in January 2022 and the first annual safety board assessment has deemed the trial safe and recommended continuation. We have launched the first adequately powered multi-center pragmatic controlled randomized clinical trial regarding NG tube use after esophagectomy with gastric conduit reconstruction.
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| 4. |
- Jestin Hannan, Christine, et al.
(author)
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Differences in multidisciplinary cancer conferences of esophageal and gastroesophageal junctional cancer regarding staging, resectability and treatment allocation – a multicenter study
-
Other publication (other academic/artistic)abstract
- Background: There are differences in esophageal cancer care across different regions in Sweden. According to Swedish national guidelines, all patients diagnosed with these tumors should be individually evaluated by regional multidisciplinary cancer conferences (MCCs) to be recommended best possible treatment. The aim of the study was to investigate differences between the regional MCCs in Sweden regarding clinical staging and recommended treatment.Method: Representatives for all six regional MCCs were invited to contribute with ten retrospective consecutive cases each. After anonymization radiological investigations were presented, along with the original case-specific medical history, anew at all participating regional MCCs. Each MCCs’ clinical Tumor Nodal Metastasis classification (cTNM) and treatment recommendation (curative, palliative or best supportive care) were compared between MCCs as well as with the original assessment. Results: Five regional MCCs joined the study. Out of 50 available cases the majority were assessed anew in addition to the previous original assessment. There was not consensus among the regional MCCs regarding cT-stage in 42 cases (84%), cN-stage in 33 cases (66%), and for cM-stage in 16 cases (32%). Differences in appraisal were not associated with PET-CT availability. The MCCs agreed on treatment recommendations in 26/50 cases (52%). Discussion: The study shows differences, both in assessment of cTNM as well as treatment recommendations at different MCCs. A patient recommended curative treatment by one MCC could be suggested palliative care by another. To achieve more equal care for esophageal cancer patients in Sweden it is essential to increase consensus on cTNM and recommended treatment.
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| 5. |
- Jestin Hannan, Christine, et al.
(author)
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Differences in multidisciplinary team assessment on esophageal cancer patients in Sweden : a multicentre study
- 2022
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In: Diseases of the esophagus. - : Oxford University Press. - 1120-8694 .- 1442-2050. ; 35:Suppl. 2
-
Journal article (peer-reviewed)abstract
- There are differences in esophageal cancer care across different counties in Sweden. According to national guidelines, all patients should be offered equal care which should be administrated by regional multidisciplinary cancer conferences (MCCs). The aim of the study was to investigate differences between the six regional MCCs in Sweden regarding clinical stageing and recommended treatment.Ten consecutive cases per participating center, 60 cases in total, were planned for inclusion. After anonymization the radiological investigations were presented, along with the original case-specific medical history, anew at the six regional MCCs. Estimation of clinical TNM and treatment allocation (curative, palliative or best supportive care) were compared between MCCs as well as with the original assessment. Interim analysis was performed in April 2022 when ten cases had been presented at five of the six regional MCCs.All available cases were assessed at five MCCs in addition to the previous original assessment (60 assessments). The mean age for the first ten cases was 74.8 years (SD ± 9.8 years). Eight out of ten cases were men. In estimations of T- and N-stage the MCCs agreed in only one out of ten cases. In half of the cases more than three different estimations of N-stage were made. For clinical M-stage there was exact agreement in three cases. In determination of recommended treatment, all five MCCs were in agreement on half of the cases.Preliminary data show striking differences, both in assessment of TNM as well as treatment recommendation at different MCCs. One patient, recommended curative treatment by one MCC could be allocated to palliative care by another. Inclusion is ongoing and further analysis of these differences are warranted to achieve more equal care for esophageal cancer patients in Sweden.
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| 6. |
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| 7. |
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| 8. |
- Ljungkrantz, Oscar, 1978, et al.
(author)
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A formal specification language for PLC-based control logic
- 2010
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In: Proceedings of the 8th IEEE International Conference on Industrial Informatics, INDIN 2010; Osaka; 13 July 2010 through 16 July 2010. - 1935-4576. - 9781424473007 ; , s. 1067-1072
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Conference paper (peer-reviewed)abstract
- Formal verification, using model checking tools, is promising in developing (IEC 61131) industrial control logic. Formal verification requires a formal specification of the properties to be verified. Specifications in model checking tools are typically expressed using temporal logic. However, the standard temporal logic dialects are not well suited for control engineers who do rarely have a background within computer science. In this paper a new dialect of linear temporal logic, ST-LTL, is introduced that intends to be easier to use for control engineers than the existing dialects. The relation of ST-LTL compared to existing temporal logic dialects is analyzed. © 2010 IEEE.
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| 9. |
- Ljungkrantz, Oscar, 1978, et al.
(author)
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A Study of Industrial Logic Control Programming Using Library Components
- 2007
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In: Proceedings of the 3rd Annual IEEE Conference on Automation Science and Engineering.
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Conference paper (peer-reviewed)abstract
- In this paper a study of logic control programming practices and use of library components at two European car manufacturers, is presented. The research provides results important to consider for researchers and PLC vendors when developing frameworks for control program generation, to cope with new requirements of flexible manufacturing systems. The main observations are: the programs, written mainly in Ladder Diagrams and Sequential Function Charts, frequently reuse pre-developed function blocks; it is important that the control programs can be understood and used for trouble-shooting by the operators; and finally, the code handles, besides automatic control, also safety and supervision, human machine interface, product data, communication etc., the code for automatic control is a minor part of the total code.
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| 10. |
- Ljungkrantz, Oscar, 1978, et al.
(author)
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An Empirical Study of Control Logic Specifications for Programmable Logic Controllers
- 2014
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In: Empirical Software Engineering. - : Springer Science and Business Media LLC. - 1573-7616 .- 1382-3256. ; 19:3, s. 655-677
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Journal article (peer-reviewed)abstract
- This paper presents an empirical study of control logic specifications used to document real-world code in manufacturing applications. More than one hundred input/output related property specifications from ten different reusable function blocks were investigated. The main purpose of the study was to provide understanding of how the specifications are expressed by industrial practitioners. This study can be used to develop new tools and methods for specifying control logic software, as well as evaluating existing ones. In this paper, the studied specifications are used to evaluate linear temporal logic in general and the specification language ST-LTL, tailored for functions blocks, in particular.The study shows that most specifications are expressed as implications between input and output conditions, which should always be fulfilled. Many of these implications are rather complex since the input and output conditions may be mixed and involve sequences, timer issues and non-boolean variables. Using ST-LTL it was possible to represent all implications of this study. The remaining few specifications could be specified in ST-LTL as well after being altered to suit the specification language. The paper demonstrates some advantages of ST-LTL compared to standard linear temporal logic and discusses possible improvements such as support for automatic rewrite of complex specifications.
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| 11. |
- Ljungkrantz, Oscar, 1978, et al.
(author)
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Formal Specification and Verification of Components for Industrial Logic Control Programming
- 2008
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In: Proceedings of the 4th IEEE Conference on Automation Science and Engineering. ; , s. 935-940
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Conference paper (peer-reviewed)abstract
- Component based approaches to develop industrial logic control programs promise to shorten development and modification times, and to lessen programming errors. However, to get these benefits it is important that components verified to work properly are reused. This work proposes using Reusable Automation Components (RACs), which contain not only the implementation but also a formal specification defining the correct use and behaviour of the component. This specification uses temporal logic to describe relations over time. The specification is helpful both for users of the components and for developers since the complete RAC including the specification can be translated into input to a tool for formal verification, to determine whether the specification is fulfilled or not. This paper shows how the RAC can be both implemented and specified using the common IEC 61131 standard and Ladder Diagrams. An industrial example is presented, specified and formally verified. It shows that RACs may help the developers to find errors and inconsistencies within the components, making it easier to do modifications of the code.
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| 12. |
- Ljungkrantz, Oscar, 1978, et al.
(author)
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Formal Specification and Verification of Industrial Control Logic Components
- 2010
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In: IEEE Transactions on Automation Science and Engineering. - 1558-3783 .- 1545-5955. ; 7:3, s. 538-548
-
Journal article (peer-reviewed)abstract
- Component-based programming frameworks for industrial control logic development promise to shorten development and modification times, and to reduce programming errors. To get these benefits, it is, however, important that the components are specified and verified to work properly. This work introduces Reusable Automation Components (RACs), which contain not only the implementation details but also a formal specification defining the correct use and behaviour of the component. This formal specification uses temporal logic to describe time-related properties and has a special structure developed to meet industrial control needs. The RAC can be formally verified, to determine whether the implementation fulfils the specification or not. A RAC prototype development tool has been developed to demonstrate this capability. The main difference between the RAC and other frameworks for formal verification of control logic is the specification modeling. In RAC, not only the implementation but also the specification is based on the structure and languages of conventional control logic, aiming at being easy to comprehend for control logic engineers. Several industrial examples are discussed in this paper, showing the benefits and potential of the framework. Note to Practitioners-Today robots and machines in automated production are usually controlled by a special industrial computer called Programmable Logic Controller (PLC). Although PLC programs are widely used in manufacturing industry, current programs tend to be difficult and time-consuming to modify when needed. They are also often tested to work first on the real equipment, which may be expensive since the regular production is stopped for code testing and error resolving. In this work, we introduce Reusable Automation Components (RACs), to facilitate PLC program development. Reusing components may speed up the development and also reduce the number of errors, if the components are already verified to work properly before the reuse. To achieve this, the RACs can be richly specified, defining the correct use and behaviour of the components. The specification can then be used to verify, formally, whether the RAC works correctly or not, according to the specification. Formal verification uses math-based models and algorithms to automatically explore all possible behaviours of the component. The RAC can be automatically translated to a tool that performs the formal verification and shows counterexamples if the specification is not fulfilled. The specification and verification of RACs are intended to be useful for control logic engineers. Hence, the specification of the RAC is based on the structure and languages of conventional PLC programs. This paper discusses a number of industrial examples which show the applicability of the RACs. The RAC framework can be further improved, especially by developing guidelines and aid for writing the specifications.
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| 13. |
- Ljungkrantz, Oscar, 1978, et al.
(author)
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Implementing a Control System Framework for Automatic Generation of Manufacturing Cell Controllers
- 2007
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In: 2007 IEEE International Conference on Robotics and Automation, ICRA'07; Rome; Italy; 10 April 2007 through 14 April 2007. - 1050-4729. - 9781424406029 ; , s. 674-679
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Conference paper (peer-reviewed)abstract
- Quickly adapting the manufacturing system to the production of new or modified products is critical for manufacturers in order to stay competitive. For flexible manufacturing systems this typically implies modifications of the control programs. In previous work a framework for automatic generation of cell controllers has been developed. In this paper an implementation of the framework is presented. Important properties of the presented implementation are: the information from earlier design phases is reused; automatic code generation for faster development and reduced implementation errors; the supervisory control theory is used to generate control functions that are correct by construction; object oriented principles are used in order to allow the reuse of existing library functions. The implementation is generic in the sense that it may generate control programs for a number of target platforms, but in this paper the focus is on generating a control program for the Java platform. An industrial example of a reconfigurable manufacturing cell has been used in the implementation process and shows that the framework is feasible for large manufacturing systems.
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| 14. |
- Ljungkrantz, Oscar, 1978, et al.
(author)
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Practice of Industrial Control Logic Programming using Library Components
- 2010
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In: Programmable Logic Controller. - 9789537619633 ; , s. 17-32
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Book chapter (other academic/artistic)abstract
- This chapter discusses Programmable Logic Controller (PLC) programming practice, particularly the use of library components, in the automotive industry. A study of program structure and use of library components at two European car manufacturers is presented. The main purpose of the study is to provide understanding of current PLC programming in industry.
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| 15. |
- Ljungkrantz, Oscar, 1978, et al.
(author)
-
Reusable Components for Industrial Logic Control Programming
- 2008
-
Reports (other academic/artistic)abstract
- This paper addresses the problem of developing logic control programs in industry to cope with new requirements of flexible manufacturing systems. We propose a component based approach in which the control program is developed using Reusable Automation Components (RACs). Reusing components may speed up the development and also make the control program have fewer bugs. To get these benefits it is important that components already verified to work properly are reused. The RACs thus contain not only the implementation but may also be richly specified, using concepts from Design by Contract in object-oriented software development. The specification is helpful both for users of the components and for developers since the complete RAC including the specification can be translated to a tool for formal verification, to determine whether the specification is fulfilled or not. The RAC is introduced for general implementation languages and it is in this paper shown in detail how the RAC can be implemented and specified using the common IEC 61131 standard and especially Ladder Diagrams, the most common language today for logic control programs. An example RAC is specified, implemented and finally verified.
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| 16. |
- Ljungkrantz, Oscar, 1978, et al.
(author)
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Towards Industrial Formal Specification of Programmable Safety Systems
- 2012
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In: IEEE Transactions on Control Systems Technology. - 1063-6536 .- 1558-0865. ; 20:6, s. 1567-1574
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Journal article (peer-reviewed)abstract
- Formal methods for specification and verification are promising in developing PLC (Programmable Logic Controller) programs in manufacturing industry. Particularly this holds for safety PLCs, used to protect humans and equipment from injuries and damages. An important challenge though, is the development of formal specifications, typically a tough task for control engineers. This paper proposes a systematic work procedure that can be used as a first step of developing formal specifications of safety PLC programs in industry. The work procedure intends to facilitate the development of relevant formal properties for safety PLC program components. The formal specifications can be used for automatic formal verification of the components, using model checking techniques. The paper shows how the work procedure has been applied to industrial safety components, resulting in relevant and nontrivial specifications.
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| 17. |
- Löfgren, Anna, et al.
(author)
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Hospital costs and health-related quality of life from complications after esophagectomy
- 2021
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In: European Journal of Surgical Oncology. - : Elsevier BV. - 0748-7983. ; S0748-7983:20, s. 30804-0
-
Journal article (peer-reviewed)abstract
- Background: Approximately 50% of all patients undergoing esophagectomy experience complications. This paper estimates the costs due to complications after esophagectomy in a Swedish context. Material and methods: The Swedish National Register for Esophageal and Gastric Cancer (NREV) and the Healthcare Consumption Register in Region Skåne (RSVD) were crossmatched for patients undergoing esophagectomy between 2010 and 2015 in Region Skåne, Sweden (n = 132). Multivariable linear regression analysis was performed on the logarithm of total healthcare cost. HRQoL was presented descriptively. Results: The mean total healthcare costs were 335,016 SEK (€33,502) for the group with no complications and 438,320 SEK (€43,832) and 808,461 SEK (€80,846) for minor and major complications (p < 0.001), respectively. Pneumonia (p < 0.001), laryngeal nerve paresis (p = 0.002) and other complications (p < 0.001) showed significant associations with increased healthcare cost. No significant difference was found in QALY-weights between the complication grades. Patients that underwent esophagectomy reported poorer HRQoL than the scores valued by the general background population. Conclusion: Complications following esophagectomy incrementally increase the healthcare costs, where more severe complications led to higher healthcare costs. The severity of complications did not affect the mean QALY-weights.
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| 18. |
- Rejmstad, Peter, 1986-, et al.
(author)
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A laser Doppler system for monitoring of cerebral microcirculation: implementation and evaluation during neurosurgery
- 2016
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In: Medical and Biological Engineering and Computing. - : Springer Berlin/Heidelberg. - 0140-0118 .- 1741-0444. ; 54:1, s. 123-131
-
Journal article (peer-reviewed)abstract
- The aim of this study was to adapt and evaluate laser Doppler perfusion monitoring (LDPM) together with custom designed brain probes and software for continuous recording of cerebral microcirculation in patients undergoing neurosurgery. The LDPM system was used to record perfusion and backscattered light (TLI). These parameters were displayed together with the extracted heart rate (HR), pulsatility index (PI) and signal trends from adjustable time intervals. Technical evaluation was done on skin during thermal provocation. Clinical measurements were performed on ten patients undergoing brain tumour surgery. Data from 76 tissue sites were captured with a length varying between 10 s to 15 min. Statistical comparisons were done using Mann-Whitney tests. Grey and tumour tissue could be separated from white matter using the TLI-signal (p < 0.05). The perfusion was significantly higher in grey and tumour tissue compared to white matter (p < 0.005). LDPM was successfully used as an intraoperative tool for monitoring local blood flow and additional parameters linked to cerebral microcirculation (perfusion, TLI, heart rate and PI) during tumour resection. The systems stability opens up for studies in the postoperative care of patients with e.g. traumatic brain injury or subarachnoid haemorrhage.
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| 19. |
- Zeyara, Adam, et al.
(author)
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Third time recurrent Boerhaave’s syndrome : a case report
- 2021
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In: Journal of Medical Case Reports. - : Springer Science and Business Media LLC. - 1752-1947. ; 15:1
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Journal article (peer-reviewed)abstract
- Background: Effort rupture of the esophagus or Boerhaave’s syndrome is a rare entity, and prognosis is largely dependent on early diagnosis and treatment. Recurrent effort ruptures are very rare, only reported in a few case reports in English literature. We present a case with a third time effort rupture, and to the best of our knowledge there are no such previous publications. Furthermore, the presented case is also distinct because each episode was treated by different methods, reflecting the pathophysiology of recurrent disease as well as the last decade’s advancements in the management of esophageal perforations in our clinic and globally. Case presentation: The patient is a 60-year-old White male, suffering from alcohol abuse, mild reflux esophagitis, and a history of effort esophageal ruptures on two previous occasions. He was now admitted to our ward once again because of a third bout of Boerhaave’s syndrome. The first time, 10 years ago, he was managed by thoracotomy and laparotomy with primary repair, and the second time, 5 years ago, by transhiatal mediastinal drainage through a laparotomy and endoscopic stent placement. Now he was successfully managed by endovascular vacuum-assisted closure therapy alone. Conclusions: Recurrent cases of Boerhaave’s syndrome are very rare, and treatment must be tailored individually. The basic rationale is, however, no different from primary disease: (1) early diagnosis, (2) adequate drainage of extraesophageal contamination, and (3) restoration of esophageal integrity. Recurrent disease is usually contained and exceptionally suitable for primary endoscopic treatment. To cover the full panorama and difficult nature of complex esophageal disease, endoscopic modalities such as stent placement and endovascular vacuum-assisted closure, as well as the capacity for prompt extensive surgical interventions such as esophagectomy, should be readily accessible within every modern esophageal center.
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| 20. |
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| 21. |
- Åkesson, Oscar, et al.
(author)
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Early endoscopic assessment after esophagectomy can predict anastomotic complications : a novel scoring system
- 2022
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In: Surgical Endoscopy. - : Springer Science and Business Media LLC. - 0930-2794 .- 1432-2218. ; 36:3, s. 1903-1909
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Journal article (peer-reviewed)abstract
- Background: Anastomotic leakage after esophagectomy is a serious and demanding complication. Early detection and treatment can probably prevent clinical deterioration of the patient. We have used early endoscopic assessment and a novel endoscopy score to predict anastomotic complications. Methods: 57 patients planned for Ivor Lewis esophagectomy were included. Endoscopy videos were recorded and biopsies were taken from the gastric conduit on day 7 or 8 after esophagectomy. A scoring system based on the endoscopic appearance, the combined endoscopy score (0–6), was developed. Scoring of the videos was done blinded. Patient outcome with regards to anastomotic complications was registered on postoperative day 30 in accordance with the ECCG definitions and compared to histopathology assessment and the combined endoscopy score retrospectively. Results: The rate of anastomotic defect (necrosis and leakage, ECCG definitions) was 19%. 7 out of 8 patients with a combined endoscopy score of ≥ 4 developed anastomotic defects. The combined endoscopy score was the only predictor for anastomotic complications. Conclusion: Prediction of anastomotic complications enables early detection and treatment which often limits the clinical extent of the complication. Early postoperative endoscopy is safe and a relatively simple procedure. The combined endoscopy score is an accurate tool to predict anastomotic complications.
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| 22. |
- Åkesson, Oscar, et al.
(author)
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Surface Microdialysis Detects Ischemia After Esophageal Resection : An Experimental Animal Study
- 2020
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In: Journal of Surgical Research. - : Elsevier. - 0022-4804 .- 1095-8673. ; 245, s. 537-543
-
Journal article (peer-reviewed)abstract
- BACKGROUND: After an esophageal resection, continuity is commonly restored by a gastric tube reconstruction and an intrathoracic anastomosis to the remaining proximal esophagus. Ischemia of the anastomotic region is considered to play a pivotal role in anastomotic leakage. Microdialysis (μD) is an excellent method to measure local biochemical substances and parameters in a specific organ or compartment aiming at early detection of ischemia. This animal study evaluates ischemia of the gastric tube reconstruction using a novel method-μD on organ surfaces. This promising method may have the potential to detect an anastomotic leakage before clinical symptoms develop.METHODS: Anesthetized normoventilated pigs were used. Surface microdialysis (S-μD) catheters and an intraparenchymal oxygen tension catheter were placed on the stomach. A gastric tube was made and the gastroepiploic artery was divided halfway along the greater curvature to produce severe ischemia at the top of the gastric tube. μD data from four locations (gastric tube, ileum and peritoneal cavity) were recorded every 20 min during the experiment. Tissue samples from all catheter sites underwent histopathological analysis. Intraparenchymal oxygen partial pressure, systemic blood tests, and hemodynamic parameters were recorded.RESULTS: S-μD data showed values indicating severe ischemia at the top of the gastric tube and intermediate ischemia at the level of transection of the gastroepiploic artery. Ischemia was verified by histopathological analysis of tissue samples and intraparenchymal oxygen tension data.CONCLUSIONS: S-μD can detect and grade severity of local ischemia in real time, in an animal model.
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| 23. |
- Åkesson, Oscar, et al.
(author)
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Surface microdialysis measures local tissue metabolism after Ivor Lewis esophagectomy; an attempt to predict anastomotic defect
- 2023
-
In: Diseases of the esophagus. - : Oxford University Press. - 1120-8694 .- 1442-2050. ; 36:8
-
Journal article (peer-reviewed)abstract
- Anastomotic defect (AD) after esophagectomy can lead to severe complications with need for surgical or endoscopic intervention. Early detection enables early treatment and can limit the consequences of the AD. As of today, there are limited methods to predict AD. In this study, we have used microdialysis (MD) to measure local metabolism at the intrathoracic anastomosis. Feasibility and possible diagnostic use were investigated. Sixty patients planned for Ivor Lewis esophagectomy were enrolled. After construction of the anastomosis, surface MD (S-MD) probes were attached to the outer surface of the esophageal remnant and the gastric conduit in close vicinity of the anastomosis and left in place for 7 postoperative days (PODs). Continuous sampling of local tissue concentrations of metabolic substances (glucose, lactate, and pyruvate) was performed postoperatively. Outcome, defined as AD or not according to Esophagectomy Complications Consensus Group definitions, was recorded at discharge or at first postoperative follow up. Difference in concentrations of metabolic substances was analyzed retrospectively between the two groups by means of artificial neural network technique. S-MD probes can be attached and removed from the gastric tube reconstruction without any adverse events. Deviating metabolite concentrations on POD 1 were associated with later development of AD. In subjects who developed AD, no difference in metabolic concentrations between the esophageal and the gastric probe was recorded. The technical failure rate of the MD probes/procedure was high. S-MD can be used in a clinical setting after Ivor Lewis esophagectomy. Deviation in local tissue metabolism on POD 1 seems to be associated with development of AD. Further development of MD probes and procedure is required to reduce technical failure.
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| 24. |
- ÅKESSON, OSCAR, et al.
(author)
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Surface microdialysis on small bowel serosa in monitoring of ischemia
- 2016
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In: Journal of Surgical Research. - : Elsevier BV. - 0022-4804 .- 1095-8673. ; 204:1, s. 39-46
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Journal article (peer-reviewed)abstract
- Background: Ischemic injury of an organ causes metabolic change from aerobic to anaerobic metabolism. It has been shown in experimental studies on the heart and liver that such conversion may be detected by conventional microdialysis probes placed intraparenchymatously, as well as on organ surfaces, by assaying lactate, pyruvate, glucose, and glycerol in dialysate. We developed a microdialysis probe (S-mu D) intended for use solely on organ surfaces. The aim of this study was to assess whether the newly developed S-mu D probe could be used for detection and monitoring of small bowel ischemia. Methods: In anesthetized normoventilated pigs, a control S-mu D probe was applied on the jejunal serosa 50 cm downstream from the duodenojejunal junction (DJJ). Starting 100 cm from DJJ, a 100-cm long ischemic segment was created by division of all mesenteric vessels. S-mu Ds were applied at 2.5, 5, 20, and 50 cm from the starting point of ischemia by serosal sutures. A standard mu D probe was placed in the abdominal cavity as a further control. Dialysate was harvested before inducing ischemia and subsequently every 20 min for 4 h. Central venous blood was drawn every hour to monitor systemic lactate, C-reactive protein, and white blood cell count. Results: Microdialysis lactate levels were significantly higher than baseline from 20 min on into protocol time in the ischemic segment and in the control S-mu D probe. The peritoneal cavity probe showed no significant elevation. Lactate levels from the ischemic segment reached a plateau at 60 min. Courses of pyruvate, glucose, and glycerol levels were in accordance with transition from an aerobic to anaerobic metabolism in the bowel wall. No statistically significant changes in hemoglobin, white blood cell count, or lactate values in central venous blood were recorded. Conclusions: Assaying the aforementioned compounds in dialysate, harvested by the newly developed S-mu D probe, allowed detection and monitoring of small bowel ischemia from 20 min on following its onset.
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