Tissue oxygen saturation during colorectal surgery measured by near-infrared spectroscopy: pilot study to predict anastomotic complications

Evaluation of anastomotic blood supply during digestive tract reconstruction with the use of the oxygen saturation index: A pooling up analysis

PURPOSE

Anastomotic leakage (AL) is one of the most serious clinical complications in digestive tract reconstruction (DTR) surgery, and it is currently hypothesized that this may be related to insufficient anastomotic blood supply. Thus, Therefore, we aimed to assess the ability of tissue oxygen saturation(StO2) as a measure to evaluate anastomotic blood supply.

METHODS

A comprehensive literature search was performed using Embase, PubMed and Cochrane Library. StO2 was used as an evaluation index of anastomotic blood supply after DTR to analyze the potential association between this index and the occurrence of AL in the postoperative period.

RESULTS

A total of eleven articles involving 867 participants were included in this systematic review and meta-analysis. After pooling the standardized mean difference (SMD) and 95% confidence intervals (Cls), low StO2 was found to be an independent risk factor for AL (P < 0.00001; 95%CI: 1.02 [0.53-1.51]). The mean StO2 in the AL group (62.3%) was significantly lower than that in the non-AL group (74.3%); AL incidence increased with the reduction of StO2 to a certain value to 201.8% and 338.1% respectively.

CONCLUSION

Oxygen saturation index can be utilized in DTR to accurately and quantitatively evaluate the anastomotic blood supply to reduce the probability of postoperative AL.

Implementation of intraoperative procedures to prevent anastomotic leak in low anterior rectal resections: a pilot study for a novel technique to evaluate anastomotic vascularization

INTRODUCTION

Altered vascular microcirculation is recognized as a risk factor for anastomotic leakage (AL) in colorectal surgery. However, few studies evaluated its impact on AL using different devices, with heterogeneous results. The present study reported the initial experience measuring gut microcirculatory density and flow with the aid of incidence dark-field (IDF) videomicroscopy (Cytocam, Braedius, Amsterdam, The Netherlands) comparing its operative outcome using a propensity score matching (PSM) model based on age, gender, and Charlson Comorbidity Index (CCI).

MATERIALS AND METHODS

Videos from 5 different sites (at least 10 s/site) were recorded from both the mucosal and serosal site of the left colon end after the colonic resection. Total vessel density (TVD), Perfused Vessel Density (PVD), De Backer score, Proportion of Perfused Vessels (PPV), and Microvascular Flow Index (MFI) were analyzed. At each recording, noninvasive measurements of blood pressure, heart rate, temperature, use of vasoactive drugs, and peripheral oxygen saturation were simultaneously recorded. The association between postoperative outcomes and microcirculation evaluation was investigated using PSM analyses.

RESULTS

Ninety-nine patients were included in the Cytocam group. The mean TVD small was 8.9 ± 2.8 mm/mm2, the PPV small % was 100 in all patients but 1, while the MFI was 3 in all patients. The mean PVD small was 8.76 ± 2.8 mm/mm2 and the mean De Becker score was 4.4 ± 1.3. In 2 patients (10.5%), the finding of altered vascularization resulted in the change of the operative strategy with an extension of the resection point. AL occurred in 2 patients of the No Cytocam group (p = 0.811).

CONCLUSION

This type of anastomotic evaluation has shown to be feasible, safe, and useful in easily detecting any alteration of the resected colon before anastomotic construction. Moreover, this technology could offer a more cost-effective manner than other devices.

Evaluation of the blood flow in reconstructed gastric tube and its relation to anastomosis leakage

OBJECTIVES

Anastomotic leakage in esophageal cancer surgery may be reduced by evaluating the blood flow to the reconstructed organ, but quantitative evaluation of arterial and venous blood flow is difficult. This study aimed to quantitatively assess blood flow using a new technique, as well as determine the relationship between the blood flow in the gastric tube and anastomotic leakage using near-infrared spectroscopy.

METHODS

This single-center, observational study included 50 patients aged 51-82 years who underwent radical esophagectomy with gastric tube reconstruction for esophageal cancer between June 2022 and January 2023. Regional tissue oxygen saturation was measured at the antrum (point X), the anastomotic point (point Z), and the midpoint between points X and Z (point Y) before and after gastric tube formation. These three points of oxygen saturation were investigated in relation to anastomotic leakage.

RESULTS

When comparing the presence of leakage to its absence, regional tissue oxygen saturation at points X and Z after gastric tube formation was significantly lower (X: p = 0.03, Z: p = 0.02), with the decreasing rate significantly higher at point Z (p = 0.01). There was no significant difference in the decreasing rate of regional tissue oxygen saturation between points X and Y (X: p = 0.052, Y: p = 0.83).

CONCLUSION

Regional tissue oxygen saturation levels may be useful for measuring blood flow and could be a predictor of anastomotic leakage.

Acute Small-bowel Obstruction: An Appraisal of Common Etiology and Management at the Federal Medical Centre, Keffi, North-central Nigeria

BACKGROUND

Acute small intestinal obstruction is a common surgical emergency in the sub-Saharan region. Over the decades, complicated inguinal hernias have been identified as a leading cause. However, we observed from our clinical practice that complicated inguinal hernias were not the most common etiology.

AIMS AND OBJECTIVES

This study aimed to evaluate the common etiology of acute small bowel obstruction in the study center and compare our findings with that from other centers and existing literature.

MATERIALS AND METHODS

This was a retrospective, cross sectional study carried out over a period of five years (January 2017 to December 2021). This study looked at the patients presenting with acute, mechanical, small bowel obstruction that did not respond to conservative treatment in our hospital facility. Relevant information were extracted from patients' clinical details and entered into the proforma prepared for this study.

RESULTS

A total of 147 patients were recruited into this study out of which 85(57.8%) were males and 62 (42.2%) were females (M:F=1.44:1). Majority (80.3%) of the patients that presented with post-operative bowel adhesion had previous appendectomy. Simple bowel obstruction was seen in 93 (63.3%) patients while strangulated obstruction and gangrenous bowel were seen in 26 (17.7%) patients and 22 (15.0%) patients respectively. Majority (47.6%) of the patients had adhesiolysis done while others had bowel resection.

CONCLUSION

The common cause of acute small bowel obstruction as observed in this study is post-operative adhesions arising from previous appendectomy and laparotomies.

Negative pressure wound therapy in patients with diabetes undergoing left internal thoracic artery harvest: A randomized control trial

BACKGROUND

Patients with diabetes undergoing CABG are at risk of wound infection. Incisional negative pressure wound therapy has been shown to be effective in decreasing incidence of infection in high-risk wounds. Near infrared spectroscopy (NIRS) can be used to assess wound oxygenation and low values can predict infection.

OBJECTIVES

To evaluate utility of NIRS to assess wound oxygenation, to assess effect of sternotomy, left internal thoracic artery harvest, and wound dressing type on wound edge oxygenation.

METHODS

In this blinded randomized control trial, patients with diabetes undergoing isolated coronary artery bypass grafting with a left internal thoracic artery were randomized to receive either incisional negative pressure wound therapy dressing or a standard dressing. NIRS measurements were made on the left upper arm (control), and left and right parasternal regions on day -1 (preoperative), day 5, and week 6 after surgery. Results were analyzed using repeated measures parametric methods.

RESULTS

Eighty patients with diabetes were recruited, 40 to the incisional negative pressure wound therapy group and 40 to the standard dressing group. Adjusted NIRS readings dropped significantly in all patients by day 5 and partially recovered by week 6. In both groups, there was no difference between readings on the left and right. At all time points and on both sides, there was no difference in readings between patients in the 2 groups.

CONCLUSIONS

NIRS can be used to assess oxygenation adjacent to a sternotomy wound. Adjusted tissue oxygen levels change with time after sternotomy and left internal thoracic artery harvest in patients with diabetes. Wound dressing type does not influence day 5 wound edge oxygenation.

Anastomotic perfusion assessment with indocyanine green in robot-assisted low-anterior resection, a multicenter study of interobserver variation

BACKGROUND

Securing sufficient blood perfusion to the anastomotic area after low-anterior resection is a crucial factor in preventing anastomotic leakage (AL). Intra-operative indocyanine green fluorescent imaging (ICG-FI) has been suggested as a tool to assess perfusion. However, knowledge of inter-observer variation among surgeons in the interpretation of ICG-FI is sparse. Our primary objective was to evaluate inter-observer variation among surgeons in the interpretation of bowel blood-perfusion assessed visually by ICG-FI. Our secondary objective was to compare the results both from the visual assessment of ICG and from computer-based quantitative analyses of ICG-FI between patients with and without the development of AL.

METHOD

A multicenter study, including patients undergoing robot-assisted low anterior resection with stapled anastomosis. ICG-FI was evaluated visually by the surgeon intra-operatively. Postoperatively, recorded videos were anonymized and exchanged between centers for inter-observer evaluation. Time to visibility (TTV), time to maximum visibility (TMV), and time to wash-out (TWO) were visually assessed. In addition, the ICG-FI video-recordings were analyzed using validated pixel analysis software to quantify blood perfusion.

RESULTS

Fifty-five patients were included, and five developed clinical AL. Bland-Altman plots (BA plots) demonstrated wide inter-observer variation for visually assessed fluorescence on all parameters (TTV, TMV, and TWO). Comparing leak-group with no-leak group, we found no significant differences for TTV: Hazard Ratio; HR = 0.82 (CI 0.32; 2.08), TMV: HR = 0.62 (CI 0.24; 1.59), or TWO: HR = 1.11 (CI 0.40; 3.11). In the quantitative pixel analysis, a lower slope of the fluorescence time-curve was found in patients with a subsequent leak: median 0.08 (0.07;0.10) compared with non-leak patients: median 0.13 (0.10;0.17) (p = 0.04).

CONCLUSION

The surgeon's visual assessment of the ICG-FI demonstrated wide inter-observer variation, there were no differences between patients with and without AL. However, quantitative pixel analysis showed a significant difference between groups.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04766060.

Assessment of Anastomotic Viability With Spectroscopic Real-time Oxygen Saturation Measurement in a Porcine Study

OBJECTIVE

Anastomotic leakage (AL) is a severe complication following intestinal procedures. Intra.Ox™ by ViOptix Inc (Newark, CA, USA) is a novel, FDA-approved spectroscopic device which enables real-time measurement of mixed tissue oxygen saturation (StO₂). Using a porcine model, this study explores the correlation between StO₂ measurements and AL formation as well as investigates the applicability of Intra.Ox™ in the clinical setting.

METHODS

Eleven female swine were divided into 3 groups to explore AL formation in different ischemic conditions. Group 1: 100% mesenteric-vascular ligation, n = 3; Group 2: 50% ligation, n = 5; Group 3: No mesenteric ligation, n = 3. StO₂ at the anastomotic line was measured before and after vessel ligation and anastomosis. Measurements were taken at 6 distinct locations along afferent and efferent loops. AL was evaluated on postoperative day 5 by re-laparotomy.

RESULTS

AL rate was 100%, 60% and 0% in groups 1, 2 and 3, respectively. Post-anastomotic StO₂ in group 1 (22.9 ± 18.5%) and 2 (39.2 ± 20.1%) were significantly lower than in group 3 (53.1 ± 8.3%, p<.0001). Post-anastomotic StO₂ readings ≤40% indicated AL potential with 100% sensitivity,+ 80% specificity, positive predictive value of 85.7% and negative predictive value of 100%.

CONCLUSION

This study demonstrates the value of Intra.Ox™ in assessing local perfusion and indicate the association between low StO₂ and AL by providing accurate, real-time, noninvasive tissue oxygenation measurements at anastomotic sites. Further studies are required to investigate the clinical application of this novel device in intestinal surgery.

Prediction of anastomotic leakage after left-sided colorectal cancer surgery: a pilot study utilizing quantitative near-infrared spectroscopy

BACKGROUND

Anastomotic leakage (AL) occurs with some frequency in all types of colorectal cancer surgery and is associated with increased morbidity, mortality and recurrence rates. Complications might be prevented by monitoring intra-operative bowel perfusion at the anastomotic site. A pilot study concerning the objective and quantitative measurement of tissue perfusion by monitoring regional tissue saturation of oxygen (rSO₂) was conducted, using the In Vivo Optical Spectroscopy (INVOS™) system (Medtronic, Minneapolis, MN, USA).

METHODS

This study evaluated the ability of the INVOS™ system to predict AL after left-sided colorectal cancer surgery. rSO₂ measurements of the oral side of the site of bowel anastomosis were taken before anastomosis in 73 patients. Clinical factors, including rSO₂, were analyzed to identify risk factors for AL.

RESULTS

Among 73 patients, 6 (8.2%) experienced AL. The rSO₂ values of the oral anastomotic site were significantly lower in AL patients than in non-AL patients. In the multivariate analysis, the rSO₂ value of the oral anastomotic site was an independent risk factor for AL.

CONCLUSION

Monitoring the rSO₂ at the anastomotic site enabled the prediction of AL. A prospective study to evaluate the efficacy of the INVOS™ system for monitoring intestinal rSO₂ is in progress.

Intraoperative colon perfusion assessment using multispectral imaging

In colorectal surgery an anastomosis performed using poorly-perfused, ischaemic bowel segments may result in a leak and consequent morbidity. Traditional measures of perfusion assessment rely on clinical judgement and are mainly subjective, based on tissue appearance, leading to variability between clinicians. This paper describes a multispectral imaging (MSI) laparoscope that can derive quantitative measures of tissue oxygen saturation (SO₂ ). The system uses a xenon surgical light source and fast filter wheel camera to capture eight narrow waveband images across the visible range in approximately 0.3 s. Spectral validation measurements were performed by imaging standardised colour tiles and comparing reflectance with ground truth spectrometer data. Tissue spectra were decomposed into individual contributions from haemoglobin, adipose tissue and scattering, using a previously-developed regression approach. Initial clinical results from seven patients undergoing colorectal surgery are presented and used to characterise measurement stability and reproducibility in vivo. Strategies to improve signal-to-noise ratio and correct for motion are described. Images of healthy bowel tissue (in vivo) indicate that baseline SO₂ is approximately 75 ± 6%. The SO₂ profile along a bowel segment following ligation of the inferior mesenteric artery (IMA) shows a decrease from the proximal to distal end. In the clinical cases shown, imaging results concurred with clinical judgements of the location of well-perfused tissue. Adipose tissue, visibly yellow in the RGB images, is shown to surround the mesentery and cover some of the serosa. SO₂ in this tissue is consistently high, with mean value of 90%. These results show that MSI is a potential intraoperative guidance tool for assessment of perfusion. Mapping of SO₂ in the colon could be used by surgeons to guide choice of transection points and ensure that well-perfused tissue is used to form an anastomosis. The observation of high mesenteric SO₂ agrees with work in the literature and warrants further exploration. Larger studies incorporating with a wider cohort of clinicians will help to provide retrospective evidence of how this imaging technique may be able to reduce inter-operator variability.

Post-Operative Monitoring of Intestinal Tissue Oxygenation Using an Implantable Microfabricated Oxygen Sensor

Anastomotic leakage (AL) is a common and dangerous post-operative complication following intestinal resection, causing substantial morbidity and mortality. Ischaemia in the tissue surrounding the anastomosis is a major risk-factor for AL development. Continuous tissue oxygenation monitoring during the post-operative recovery period would provide early and accurate early identification of AL risk. We describe the construction and testing of a miniature implantable electrochemical oxygen sensor that addresses this need. It consisted of an array of platinum microelectrodes, microfabricated on a silicon substrate, with a poly(2-hydroxyethyl methacrylate) hydrogel membrane to protect the sensor surface. The sensor was encapsulated in a biocompatible package with a wired connection to external instrumentation. It gave a sensitive and highly linear response to variations in oxygen partial pressure in vitro, although over time its sensitivity was partially decreased by protein biofouling. Using a pre-clinical in vivo pig model, acute intestinal ischaemia was robustly and accurately detected by the sensor. Graded changes in tissue oxygenation were also measurable, with relative differences detected more accurately than absolute differences. Finally, we demonstrated its suitability for continuous monitoring of tissue oxygenation at a colorectal anastomosis over a period of at least 45 h. This study provides evidence to support the development and use of implantable electrochemical oxygen sensors for post-operative monitoring of anastomosis oxygenation.

Predictive and Diagnostic Biomarkers of Anastomotic Leakage: A Precision Medicine Approach for Colorectal Cancer Patients

Development of an anastomotic leak (AL) following intestinal surgery for the treatment of colorectal cancers is a life-threatening complication. Failure of the anastomosis to heal correctly can lead to contamination of the abdomen with intestinal contents and the development of peritonitis. The additional care that these patients require is associated with longer hospitalisation stays and increased economic costs. Patients also have higher morbidity and mortality rates and poorer oncological prognosis. Unfortunately, current practices for AL diagnosis are non-specific, which may delay diagnosis and have a negative impact on patient outcome. To overcome these issues, research is continuing to identify AL diagnostic or predictive biomarkers. In this review, we highlight promising candidate biomarkers including ischaemic metabolites, inflammatory markers and bacteria. Although research has focused on the use of blood or peritoneal fluid samples, we describe the use of implantable medical devices that have been designed to measure biomarkers in peri-anastomotic tissue. Biomarkers that can be used in conjunction with clinical status, routine haematological and biochemical analysis and imaging have the potential to help to deliver a precision medicine package that could significantly enhance a patient's post-operative care and improve outcomes. Although no AL biomarker has yet been validated in large-scale clinical trials, there is confidence that personalised medicine, through biomarker analysis, could be realised for colorectal cancer intestinal resection and anastomosis patients in the years to come.

Mucosal blood flow in the remaining rectal stump is more affected by total than partial mesorectal excision in patients undergoing anterior resection: a key to understanding differing rates of anastomotic leakage?

Purpose

Anterior resection is the procedure of choice for tumours in the mid and upper rectum. Depending on tumour height, a total mesorectal excision (TME) or partial mesorectal excision (PME) can be performed. Low anastomoses in particular have a high risk of developing anastomotic leakage, which might be explained by blood perfusion compromise. A pilot study indicated a worse blood flow in TME patients in an open setting. The aim of this study was to further evaluate perianastomotic blood perfusion changes in relation to TME and PME in a predominantly laparoscopic context.

Method

In this prospective cohort study, laser Doppler flowmetry was used to evaluate the perianastomotic colonic and rectal perfusion before and after surgery. The two surgical techniques were compared in terms of mean differences of perfusion units using a repeated measures ANOVA design, which also enabled interaction analyses between type of mesorectal excision and location of measurement. Anastomotic leakage until 90 days after surgery was reported for descriptive purposes.

Results

Some 28 patients were available for analysis: 17 TME and 11 PME patients. TME patients had a reduced blood perfusion postoperatively compared to PME patients in the aboral posterior area (mean difference: −57 vs 18 perfusion units; p = 0.010). An interaction between mesorectal excision type and anterior/posterior location was detected at the aboral level (p = 0.007). Two patients developed a minor leakage, diagnosed after discharge.

Conclusion

Patients operated on using TME have a decreased blood flow in the aboral posterior quadrant of the rectum postoperatively compared to patients operated on using PME. This might explain differing rates of anastomotic leakage.

Trial registration

ClinicalTrials.gov Identifier: NCT02401100

Intraoperative perfusion assessment of the proximal colon by a visual grading system for safe anastomosis after resection in left-sided colorectal cancer patients

We aimed to evaluate the clinical feasibility of a new visual grading system. We included 50 patients who underwent resection of primary colorectal cancer. Before anastomosis, the marginal vessel was cut and the perfusion status was assessed by a visual grading system. The visual grading system is comprised of five grades according to the bleeding from the marginal vessel and is categorized into 4 groups: good (grade A and B), moderate (grade C), poor (grade D) and none (grade E). Colorectal anastomosis was performed only in the good and moderate groups. We compared postoperative outcomes between the good and moderate groups and analysed the factors affecting the perfusion grade. Among the patients, 48% were grade A, 12% were grade B, and 40% were grade C. There was no anastomotic leakage. Only one patient with grade C showed ischemic colitis and needed reoperation. Age was the only factor correlated with perfusion grade in multivariate analysis (OR 1.080, 95% CI 1.006-1.159, p = 0.034). The perfusion grades were significantly different between > 65 and < 65 year-old patients (> 65, A 29.2% B 12.5% C 58.3% vs. < 65, A 65.4% B 11.5% C 23.1%, p = 0.006). Our intraoperative perfusion assessment that uses a cutting method and a visual grading system is simple and useful for performing a safe anastomosis after colorectal resection. If the perfusion grade is better than grade C, an anastomosis can be performed safely. Age was found to be an important factor affecting the perfusion grade.

Noninvasive assessment of bowel blood perfusion using intraoperative laser speckle flowgraphy

PURPOSE

Laser speckle flowgraphy (LSFG) is a noninvasive method for quantitative evaluation of blood flow using the mean blur rate (MBR) as the blood flow index. We investigated whether LSFG can intraoperatively detect the demarcation line after vessel dissection and reduce the incidence of anastomotic leakage (AL).

METHODS

This study included 36 patients who underwent left-sided colorectal surgery. First, we compared the demarcation line (determined by LSFG) with the transection line (TL) at which the marginal vessels were divided. We then measured the MBR on both sides of the TL to determine where the MBR changed significantly. We investigated the presence or absence of significant differences between the MBR on the proximal side and that on the distal side of the TL. Finally, we retrospectively compared the patient characteristics and AL rates in the LSFG group (n = 36) and control group (n = 87).

RESULTS

In total, 58.3% (21/36) of the demarcation lines determined by LSFG matched the TL. The median distance between the demarcation line determined by LSFG and the TL was 0.0 mm (0.0-12.1 mm). The MBR sharply decreased at the TL in 80.6% (29/36) of cases. The median MBR was significantly lower on the distal than proximal side. The AL rate was not significantly lower in the LSFG group than in the control group.

CONCLUSION

LSFG accurately detected the demarcation line during surgery. However, LSFG did not reduce the incidence of AL.

Systematic Review on the Influence of Tissue Oxygenation on Gut Microbiota and Anastomotic Healing

BACKGROUND

Anastomotic leak rates have not improved over several decades despite improvements in surgical techniques and patient care. The gut microbiome has been implicated in the development of leaks. The exact mechanisms by which tissue oxygenation affects gut microbial composition and anastomotic healing physiology are unclear. Also, commonly used carbon dioxide (CO₂) is a known vasodilator that improves tissue oxygen tension. We performed a systematic review to determine the influence of hyperoxia, hypoxia, and hypercapnia on the gut microbiome and anastomotic healing.

METHODS

A literature search was performed in MEDLINE, EMBASE, and COCHRANE to identify studies investigating the effects of hyperoxia, hypoxia, and hypercapnia on anastomotic healing and gut microbiota published between 1998 and 2018. Two reviewers screened the articles for eligibility and quality. Fifty-three articles underwent full text review, and a narrative synthesis was undertaken.

RESULTS

Hyperoxia is associated with better anastomotic healing, increased gastrointestinal oxygen tension, and may reduce gut anaerobes. Hypoxia is associated with poor healing and increased gut anaerobes. However, it is unclear if hypoxia is the most important predictor of anastomotic leaks. Low pressure CO₂ pneumoperitoneum and mild systemic hypercapnia are both associated with increased gastrointestinal oxygen tension and may improve anastomotic healing. We found no studies which investigated the effect of hypercapnia on gut microbiota in the context of anastomotic healing.

CONCLUSIONS

Tissue oxygenation influences gut anastomotic healing, but little evidence exists to demonstrate the influence on the gut microbiome in the context of healing. Further studies are needed to determine if anastomotic microbiome changes with altered tissue oxygenation and if this affects healing and leak rates. If confirmed, altering tissue oxygenation through hyperoxia or hypercapnia could be feasible means of altering the microbiome such that anastomotic leak rates reduce.

Intestinal Mucosal and Serosal Microcirculation at the Planned Anastomosis during Abdominal Surgery

INTRODUCTION

Intestinal blood flow is often named as a key factor in the pathophysiology of anastomotic leakage. The distribution between mucosal and serosal microperfusion during surgery remains to be elucidated.

OBJECTIVE

The aim of this study was to assess if the mucosal microcirculation of the intestine is more vulnerable to a surgical hit than the serosal microcirculation during surgery.

METHODS

In an observational cohort study (n = 9 patients), the microcirculation of the bowel serosa and mucosa was visualized with incident dark-field imaging during surgery. At the planned anastomosis, the following microcirculatory parameters were determined: microvascular flow index (MFI), percentage of perfused vessels (PPV), perfused vessel density (PVD), and total vessel density (TVD). Data are presented as median (interquartile range [IQR]).

RESULTS

Perfusion parameters and vessel density were significantly higher for the mucosa than the serosal microcirculation at the planned site for anastomosis or stoma. Mucosal MFI was 3.00 (IQR 3.00-3.00) compared to a serosal MFI of 2.75 (IQR 2.21-2.94), p = 0.03. The PPV was 99% (IQR 98-100) versus 92% (IQR 66-94), p = 0.01. The TVD was 16.77 mm/mm2 (IQR 13.04-18.01) versus 10.42 mm/mm2 (IQR 9.36-11.81), p = 0.01, and the PVD was 15.44 mm/mm2 (IQR 13.04-17.78) versus 9.02 mm/mm2 (IQR 6.43-9.43), p = 0.01.

CONCLUSIONS

The mucosal microcirculation was preserved, while lower perfusion of the serosa was found at the planned anastomosis or stoma during surgery. Further research is needed to link our observations to the clinically relevant endpoint of anastomotic leakage.

Laser Speckle Contrast Imaging for Intraoperative Quantitative Assessment of Intestinal Blood Perfusion During Colorectal Surgery: A Prospective Pilot Study

BACKGROUND

The main limitation of perfusion assessment with indocyanine green fluorescence angiography during colorectal surgery is that the surgeon assesses the quality of perfusion subjectively. The ideal intestinal viability test must be minimally invasive, objective, and reproducible. We evaluated the quantitativity and reproducibility of laser speckle contrast imaging for perfusion assessment during colorectal surgery.

METHODS

This was a prospective, nonrandomized, pilot study of 8 consecutive patients who underwent elective left-sided colorectal resection. Laser speckle perfusion images at the site of proximal transection of the bowel were obtained intraoperatively. We tested the hypothesis that laser speckle contrast imaging was able to quantitatively identify areas of diminished intestinal perfusion after devascularization and assessed the reproducibility of this method.

RESULTS

All surgical procedures were uneventful and blood flow measurements were successfully made in all patients. None of the patients developed postoperative complications related to the anastomosis and stoma. Data analyses were successfully optimized to perform quantitative regional perfusion assessments in all cases. The bowel tissue blood flows of the anal side region adjacent to the transection line were significantly lower than those of the oral side region adjacent to the transection line after ligation of marginal vessels ( P = .012). Interrater reliability was high (intraclass correlation coefficients = 0.989), and a Bland-Altman plot showed few differences of mean flux data between 2 investigators.

CONCLUSION

Laser speckle contrast imaging is feasible for real-time assessment of bowel perfusion with quantitativity and excellent reproducibility during colorectal surgery without administration of any contrast agents.

Can sidestream dark field (SDF) imaging identify subtle microvascular changes of the bowel during colorectal surgery?

BACKGROUND

Recognition of a non-viable bowel during colorectal surgery is a challenging task for surgeons. Identifying the turning point in serosal microcirculatory deterioration leading up to a non-viable bowel is crucial. The aim of the present study was to determine whether sidestream darkfield (SDF) imaging can detect subtle changes in serosal microcirculation of the sigmoid after vascular transection during colorectal surgery.

METHODS

A prospective observational clinical study was performed at a single medical centre. All eligible participants underwent laparoscopic sigmoid resection and measurements were taken during the extra-abdominal phase. Microcirculation was measured at the transected bowel and 20 cm proximal to this point. Microcirculatory parameters such as Microvascular Flow Index (MFI), proportion of perfused vessels (PPV), perfused vessel density (PVD), total vessel density (TVD) and the Heterogeneity Index were determined. Data are presented as median (interquartile range) or mean ± standard deviation.

RESULTS

A total of 60 SDF images were acquired for 10 patients. Perfusion parameters and perfused vessel density were significantly lower at the transected bowel compared with the non-transected measurements [MFI 2.29 (1.96-2.63) vs 2.96 (2.73-3.00), p = 0.007; PPV 74% (55-83) vs 94% (86-97), p = 0.007; and PVD 7.61 ± 2.99 mm/mm² versus 10.67 ± 1.48 mm/mm², p = 0.009]. Total vessel density was similar between the measurement locations.

CONCLUSIONS

SDF imaging can identify changes of the bowel serosal microcirculation. Significantly lower serosal microcirculatory parameters of the vascular transected bowel was seen compared with the non-transected bowel. The ability of SDF imaging to detect subtle differences holds promise for future research on microvascular cut-off values leading to a non-viable bowel.

Left colic artery-preserving D3 lymphadenectomy using near-infrared spectroscopy was effective for double advanced cancers of the transverse colon and rectum: A case report

INTRODUCTION

Exact assessment of intestinal viability is necessary, since the risk of anastomotic complications increases due to the reduction in anastomotic blood supply. Near-infrared spectroscopy is useful in assessing blood flow because it allows real-time monitoring and quantifying of tissue oxygen saturation. Herein, we report a case in which two intestinal resections were performed safely by using near-infrared spectroscopy to evaluate the blood flow at the anastomotic sites.

PRESENTATION OF CASE

A 67-year-old man was diagnosed with multiple cancers of the transverse colon and rectum. Laparoscopic transverse colon resection and low anterior resection were performed along with left colic artery-preserving lymphadenectomy, including tissues around the origin of the inferior mesenteric artery. After mesenteric dissection, the tissue oxygen saturation of the proximal side and distal side stumps were 93% and 87%, respectively. The tissue oxygen saturation of the anastomotic proximal side after mesenteric dissection was 76%, thus confirming sufficient blood flow.

DISCUSSION

Performance of transverse colon resection and low anterior resection for multiple cancers of the transverse colon and rectum resulted in blockage of the blood flow to the descending colon; therefore, it was necessary to preserve the blood flow to the descending colon by preserving the left colic artery. Near-infrared spectroscopy was used to evaluate blood flow to the anastomotic sites, in order to perform the surgery safely.

CONCLUSION

Near-infrared spectroscopy is a safe, simple and low-cost method for assessing blood flow intraoperatively in conjunction with left colic artery-preserving surgery.

Intraoperative colonic pulse oximetry in left-sided colorectal surgery: can it predict anastomotic leak?

BACKGROUND

An anastomotic leak is a fairly common and a potentially lethal complication in colorectal surgery. Objective methods to assess the viability and blood circulation of the anastomosis could help in preventing leaks. Intraoperative pulse oximetry is a cheap, easy to use, fast, and readily available method to assess tissue viability. Our aim was to study whether intraoperative pulse oximetry can predict the development of an anastomotic leak.

METHODS

The study was a prospective single-arm study conducted between the years 2005 and 2011 in Helsinki University Hospital. Patient material consisted of 422 patients undergoing elective left-sided colorectal surgery. The patients were operated by one of the three surgeons. All of the operations were partial or total resections of the left side of the colon with a colorectal anastomosis. The intraoperative colonic oxygen saturation was measured with pulse oximetry from the colonic wall, and the values were analyzed with respect to post-operative complications.

RESULTS

2.3 times more operated anastomotic leaks occurred when the colonic StO₂ was ≤ 90% (11/129 vs 11/293). The mean colonic StO₂ was 91.1 in patients who developed an operated anastomotic leak and 93.0 in patients who did not. With logistic regression analysis, the risk of operated anastomotic leak was 4.2 times higher with StO₂ values ≤ 90%.

CONCLUSIONS

Low intraoperative colonic StO₂ values are associated with the occurrence of anastomotic leak. Despite its handicaps, the method seems to be useful in assessing anastomotic viability.

Clinical role of fluorescence imaging in colorectal surgery - a review

INTRODUCTION

Anastomotic leak (AL) after colorectal surgery is a devastating complication; decreased blood perfusion is an important risk factor. Surgeons rely on subjective measures to assess bowel perfusion. Fluorescence imaging (FI) with indocyanine green (ICG) provides a real-time objective assessment of intestinal perfusion. Areas covered: A PubMed search using the terms 'fluorescence imaging', 'indocyanine green', 'colon and rectal surgery' was undertaken. Sixteen articles between 2010 to present were identified. Main outcomes were leak rate reduction, change in surgical plan, and technical feasibility. Change in surgical strategy due to FI was recorded in 11 studies. Two case control studies showed overall reduction of 4% and 12% in AL rate and one showed no change in AL rate between groups. Expert commentary: According to the available literature, FI is technically feasible and alters surgical strategy in a non-negligible number of patients possibly effecting AL rates.

Intraoperative modifiable risk factors of colorectal anastomotic leakage: Why surgeons and anesthesiologists should act together

BACKGROUND

Colorectal anastomotic leakage (CAL) is a major surgical complication in intestinal surgery. Despite many optimizations in patient care, the incidence of CAL is stable (3-19%) [1]. Previous research mainly focused on determining patient and surgery related risk factors. Intraoperative non-surgery related risk factors for anastomotic healing also contribute to surgical outcome. This review offers an overview of potential modifiable risk factors that may play a role during the operation.

METHODS

Two independent literature searches were performed using EMBASE, Pubmed and Cochrane databases. Both clinical and experimental studies published in English from 1985 to August 2015 were included. The main outcome measure was the risk of anastomotic leakage and other postoperative complications during colorectal surgery. Determined risk factors of CAL were stated as strong evidence (level I and II high quality studies), and potential risk factors as either moderate evidence (experimental studies level III), or weak evidence (level IV or V studies).

RESULTS

The final analysis included 117 articles. Independent factors of CAL are diabetes mellitus, hyperglycemia and a high HbA1c, anemia, blood loss, blood transfusions, prolonged operating time, intraoperative events and contamination and a lack of antibiotics. Unequivocal are data on blood pressure, the use of inotropes/vasopressors, oxygen suppletion, type of analgesia and goal directed fluid therapy. No studies could be found identifying the impact of body core temperature or mean arterial pressure on CAL. Subjective factors such as the surgeons' own assessment of local perfusion and visibility of the operating field have not been the subject of relevant studies for occurrence in patients with CAL.

CONCLUSION

Both surgery related and non-surgery related risk factors that can be modified must be identified to improve colorectal care. Surgeons and anesthesiologists should cooperate on these items in their continuous effort to reduce the number of CAL. A registration study determining individual intraoperative risk factors of CAL is currently performed as a multicenter cohort study in the Netherlands.

Intraoperative assessment of tissue oxygen saturation of the remnant stomach by near-infrared spectroscopy in two cases of pancreatectomy following gastrectomy

INTRODUCTION

Objective and quantitative intraoperative methods of bowel viability assessment could decrease the risk of postoperative ischemic complications in gastrointestinal surgery. Because the remnant stomach and the pancreas share an arterial blood supply, it is often unclear whether the remnant stomach can be safely preserved when performing pancreaticoduodenectomy (PD) or distal pancreatectomy (DP) post gastrectomy. We herein report two cases in which the remnant stomach was safely preserved using near-infrared spectroscopy to assess the regional saturation of oxygen (rSO2) in the remnant stomach during operation.

PRESENTATION OF CASE

The first patient, a 68-year-old man, was diagnosed with cancer of the pancreatic head and underwent PD a year after proximal gastrectomy for gastric cancer. The remnant stomach was safely preserved by evaluation of the rSO2 before and after reconstruction of the arteries. The second patient, an 82-year-old woman with a history of distal gastrectomy for gastric cancer 40 years previously, was diagnosed with a main duct intraductal papillary mucinous neoplasm of the pancreatic body, requiring DP. As in the previous case, we could safely preserve the remnant stomach through assessing the intraoperative rSO2 of the remnant stomach.

DISCUSSION

Through comparing changes in the rSO2 during surgery, near-infrared spectroscopy provides objective and quantitative assessments of intestinal viability to predict ischemic complications.

CONCLUSION

This method may be a viable option to evaluate the blood supply to the alimentary tract.

Sidestream dark field imaging of the serosal microcirculation during gastrointestinal surgery

AIM

The study aimed to describe the serosal microcirculation of the human bowel using sidestream dark field imaging, a microscopic technique using polarized light to visualize erythrocytes through capillaries. We also compared its feasibility to the current practice of sublingual microcirculatory assessment.

METHOD

In 17 patients sidestream dark field measurements were performed during gastrointestinal surgery. Microcirculatory parameters like microvascular flow index (MFI), proportion of perfused vessels (PPV), perfused vessel density (PVD) and total vessel density (TVD) were determined for every patient, sublingually and on the bowel serosa.

RESULTS

Sixty measurements were done on the bowel of which eight (13%) were excluded, five owing to too much bowel peristalsis and three because of pressure artefacts. Image stability was in favour of sublingual measurements [pixel loss per image, bowel 145 (95% CI 126-164) vs sublingual 55 (95% CI 41-68); P < 0.001] and time to acquire a stable image [bowel 96 s (95% CI 63-129) vs. sublingual 46 s (95% CI 29-64); P = 0.013]. No difference in the MFI was observed [bowel 2.9 (interquartile range 2.87-2.95) vs sublingual 3.0 (interquartile range 2.91-3.0); P = 0.081]. There was a difference in the PPV [bowel 95% (95% CI 94-96) vs sublingual 97% (95% CI 97-99); P < 0.001], PVD [bowel 12.9 mm/mm2 (95% CI 11.1-14.8) vs sublingual 17.4 mm/mm2 (95% CI 15.6-19.1); P = 0.003] and the TVD [bowel 13.6 mm/mm2 (95% CI 11.6-15.6) vs sublingual 17.7 mm/mm2 (95% CI 16.0-19.4); P = 0.008].

CONCLUSION

Sidestream dark field imaging is a very promising technique for bowel microcirculatory visualization and assessment. It is comparable to sublingual assessment and the analysis produces a similar outcome with slightly differing anatomical features.

Is aortoiliac calcification linked to colorectal anastomotic leakage? A case-control study

BACKGROUND

Anastomotic leakage in bowel surgery remains a devastating complication. Various risk factors have been uncovered, however, high anastomotic leakage rates are still being reported. This study describes the use of calcification markers of the central abdominal arteries as a prognostic factor for colorectal anastomotic leakage.

METHODS

This case-control study includes clinical data from three different hospitals. Calcium volume and calcium score of the aortoiliac tract were determined by CT-scan analysis. Cases were all patients with anastomotic leakage after a left-sided anastomosis (n = 30). Three controls were randomly matched for each case. Only patients with a contrast-enhanced pre-operative CT-scan were included.

RESULTS

The measurements of the calcium score and calcium volume of the different trajectories showed that there was one significant difference with regard to the right external iliac artery. Multiple regression analysis showed a significant different negative odds ratio of the presence of calcium in the right external iliac artery.

CONCLUSION

This study demonstrates that calcium volume and calcium score of the aortoiliac trajectory does not correlate with the risk of colorectal anastomotic leakage after a left-sided anastomosis.

Fluorescence angiography in laparoscopic low rectal and anorectal anastomoses with pinpoint perfusion imaging--a critical appraisal with specific focus on leak risk reduction

BACKGROUND AND AIMS

Anastomotic dehiscence is one of the most feared complications in colorectal surgery leading to significant morbidity and mortality. Progressively lower anastomoses are associated with a greater leak rate. One of the key factors is the perfusion of the bowel to be joined. Presently, surgeons rely on a variety subjective measures to determine anastomotic perfusion and mechanical integrity however these have shortcomings. The aim of this paper is to appraise the literature on the use of fluorescence angiography (FA) in laparoscopic rectal surgery.

MATERIALS AND METHODS

A Pubmed search was undertaken using terms 'fluorescence angiography' and 'rectal surgery'. The search was expanded using the related articles function. Studies were included if they used FA specifically for rectal surgery. Outcomes of interest including anastomotic leak rate, change of operative strategy and time taken for FA were recorded.

RESULTS

Eleven papers detailing the use of FA in rectal surgery are outlined demonstrating that this technique may change operative strategy and lead to a reduction in anastomotic leak rate.

CONCLUSION

In this paper, we discuss assessment of colorectal blood supply using FA and how this technique holds great potential to detect insufficiently perfused bowel. In so doing, the operator can adjust their operative strategy to mitigate these affects with the aim of reducing the complications of anastomotic leak and stenosis. However, it is highlighted that there is a clear need for randomised controlled trials in order to determine this definitively.

Fluorescence in robotic surgery

Currently, there are several clinical applications for intraoperative ICG, such as identification of vascular and biliary anatomy, assessment of organ and tissue perfusion, lymph node mapping, and real-time identification of lesions. In this paper we present a review of the available literature related to the use of ICG fluorescence in robotic surgery in order to provide a better understanding of the current applications, show the rapid growth of this technique, and demonstrate the potential future applications.

Improving the outcomes in oncological colorectal surgery

During the last several decades, colorectal cancer surgery has experienced some major perioperative improvements. Preoperative risk-assessment of nutrition, frailty, and sarcopenia followed by interventions for patient optimization or an adapted surgical strategy, contributed to improved postoperative outcomes. Enhanced recovery programs or fast-track surgery also resulted in reduced length of hospital stay and overall complications without affecting patient safety. After an initially indecisive start due to uncertainty about oncological safety, the most significant improvement in intraoperative care was the introduction of laparoscopy. Laparoscopic surgery for colon and rectal cancer is associated with better short-term outcomes, whereas long-term outcomes regarding survival and recurrence rates are comparable. Nevertheless, long-term results in rectal surgery remain to be seen. Early recognition of anastomotic leakage remains a challenge, though multiple improvements have allowed better management of this complication.

Bedside assessment of tissue oxygen saturation monitoring in critically ill adults: an integrative review of the literature

Objective. Tissue oxygen saturation (StO2) monitoring is a noninvasive technology with the purpose of alerting the clinician of peripheral hypoperfusion and the onset of tissue hypoxia. This integrative review examines the rigor and quality of studies focusing on StO2 monitoring in adult critically ill patients. Background. Clinicians must rapidly assess adverse changes in tissue perfusion while minimizing potential complications associated with invasive monitoring. The noninvasive measurement of tissue oxygen saturation is based on near-infrared spectroscopy (NIRS), an optical method of illuminating chemical compounds which absorb, reflect, and scatter light directed at that compound. Methods. An integrative review was conducted to develop a context of greater understanding about complex topics. An Integrative review draws on multiple experimental and nonexperimental research methodologies. Results. Fourteen studies were graded at the C category. None reported the use of probability sampling or demonstrated a cause-and-effect relationship between StO2 values and patient outcomes. Conclusions. Future research should be based on rigorous methods of sampling and design in order to enhance the internal and external validity of the findings.

Intraoperative assessment of colorectal anastomotic integrity: a systematic review

BACKGROUND

Surgeons have attempted to minimize postoperative anastomotic complications by employing intraoperative tests and manoeuvres to assess colorectal anastomotic integrity. These have evolved over time with improvement in operative technology and techniques. This systematic review aims to examine the impact of such intraoperative assessments.

METHODS

A systematic review of studies assessing intraoperative anastomotic assessments and their impact on postoperative anastomotic complications was performed. Intraoperative measures undertaken as a result of intraoperative assessments and postoperative anastomotic complications were analysed.

RESULTS

37 Studies were identified. 13 studies evaluated basic mechanical patency tests, ten studies evaluated endoscopic visualisation techniques and 14 studies evaluated microperfusion techniques. Postoperative anastomotic complications were significantly lower in patients tested with basic mechanical patency tests compared to those untested (non-RCT: 4.1 vs. 8.1 %, p = 0.03, RCTs: 5.8 vs. 16.0 %, p = 0.024). There were no differences in postoperative anastomotic complications between tested and non-tested cohorts in non-randomised cohort studies evaluating endoscopic visualisation techniques. However, intraoperative measures taken after abnormal intraoperative tests may have reduced the number of postoperative complications. Perfusion analysis techniques are not in routine widespread clinical practice as yet, but newer techniques such as fluorescent dyes and imaging under near infrared light show technical feasibility.

CONCLUSIONS

Intraoperative colorectal anastomotic assessment has evolved together with advancement of technology in the surgical setting. Moderate benefit in terms of lower postoperative anastomotic complications has been shown with basic mechanical patency testing and more recently with intraoperative endoscopic visualisation of colorectal anastomoses. The next advance and possible introduction into routine practice may include the use of microperfusion techniques. The latest in this group of techniques, which utilise autofluorescent dyes such as Indocyanine green, hold great potential. Well-planned controlled studies or ideally, randomised controlled trials need to be conducted to further assess the benefit of these latest techniques.

Enhanced-reality video fluorescence: a real-time assessment of intestinal viability

OBJECTIVE

Our aim was to evaluate a fluorescence-based enhanced-reality system to assess intestinal viability in a laparoscopic mesenteric ischemia model.

MATERIALS AND METHODS

A small bowel loop was exposed, and 3 to 4 mesenteric vessels were clipped in 6 pigs. Indocyanine green (ICG) was administered intravenously 15 minutes later. The bowel was illuminated with an incoherent light source laparoscope (D-light-P, KarlStorz). The ICG fluorescence signal was analyzed with Ad Hoc imaging software (VR-RENDER), which provides a digital perfusion cartography that was superimposed to the intraoperative laparoscopic image [augmented reality (AR) synthesis]. Five regions of interest (ROIs) were marked under AR guidance (1, 2a-2b, 3a-3b corresponding to the ischemic, marginal, and vascularized zones, respectively). One hour later, capillary blood samples were obtained by puncturing the bowel serosa at the identified ROIs and lactates were measured using the EDGE analyzer. A surgical biopsy of each intestinal ROI was sent for mitochondrial respiratory rate assessment and for metabolites quantification.

RESULTS

Mean capillary lactate levels were 3.98 (SD = 1.91) versus 1.05 (SD = 0.46) versus 0.74 (SD = 0.34) mmol/L at ROI 1 versus 2a-2b (P = 0.0001) versus 3a-3b (P = 0.0001), respectively. Mean maximal mitochondrial respiratory rate was 104.4 (±21.58) pmolO2/second/mg at the ROI 1 versus 191.1 ± 14.48 (2b, P = 0.03) versus 180.4 ± 16.71 (3a, P = 0.02) versus 199.2 ± 25.21 (3b, P = 0.02). Alanine, choline, ethanolamine, glucose, lactate, myoinositol, phosphocholine, sylloinositol, and valine showed statistically significant different concentrations between ischemic and nonischemic segments.

CONCLUSIONS

Fluorescence-based AR may effectively detect the boundary between the ischemic and the vascularized zones in this experimental model.

Surgery for ischemic colitis: outcome and risk factors for in-hospital mortality

PURPOSE

Surgery for ischemic colitis is associated with high perioperative morbidity and mortality, but the risk factors for mortality and major surgical complications are unclear.

METHODS

In this retrospective single institution cohort study of all patients undergoing colorectal surgery for histologically proven ischemic colitis between 2004 and 2010, we evaluated surgical outcomes and risk factors for in-hospital mortality and major surgical complications.

RESULTS

For the 100 patients included in the study, in-hospital mortality was 54 %; major surgical complications, defined as anastomotic leakage or rectal stump and stoma complications, occurred in 16 %. In the multivariable analysis, hospital death was more likely in patients with right-sided (odds ratio [OR] 3.8; 95 % confidence interval [CI] 1.2, 12; P = 0.022) or pan-colonic ischemia (OR 11; 95 % CI 2.8, 39; P < 0.001), both relative to left-sided ischemia. Decreased preoperative pH level (OR 2.5 per 0.1 decrease; 95 % CI 1.5, 4.1; P < 0.001) and prior cardiac or aortic surgery (OR 2.4; 95 % CI 0.82, 6.8; P = 0.109) were further important risk factors for in-hospital mortality. Major postoperative surgical complications were more likely in patients with ischemic alterations at the resection margin of the histological specimen (OR 3.7; 95 % CI 1.2, 11; P = 0.022).

CONCLUSIONS

Colonic resection for ischemic colitis is associated with high in-hospital mortality, especially in patients with right-sided or pan-colonic ischemia. In patients developing acidosis, early laparotomy is essential. Since resection margins' affection seems to be underestimated upon surgery, resections should be performed wide enough within healthy tissue.

Investigating viability of intestine using spectroscopy: a pilot study

BACKGROUND

The differentiation of "viable" from "nonviable" bowel remains a challenge in the treatment of acute mesenteric ischemia. In this study, diffuse reflectance spectroscopy (DRS) was used to investigate the viability of bowel tissue after ischemia and reperfusion in an animal model in vivo and in real time.

METHODS

A total of 25 females Sprague-Dawley rats were divided into five groups based on different bowel ischemia times. In each study group for four of them, the superior mesenteric artery was occluded using a vascular clamp for a different period (i.e., 30, 45, 60, and 90 min; n = 5 for each group). Intestinal reperfusion was accomplished by releasing the clamps after the given occlusion period for each group. Spectra were acquired by gently touching the optical fiber probe to the bowel tissue before the induce ischemia, at the end of the induced ischemia, and after the reperfusion. The data acquired before the ischemia were used as a control group. Without occluding the superior mesenteric artery, the spectra were acquired on the bowel with the same time intervals of the experiments were used as a sham group (n = 5). Subsequently, the same bowel segments were sent for histopathologic examination.

RESULTS

Based on the correlation between the spectra acquired from the bowel segments and the results from the histopathologic investigation, DRS is able to differentiate the histopathologic grading that appears when the Chiu/Park score ≥5 (i.e., high-level ischemic injury) than Chiu/Park score <5. Eight out of nine low-level ischemic injury tissue samples were correctly defined using the spectroscopic classification system. All eleven high-level ischemic injury tissues that were histopathologically assigned grade 5 and above were correctly defined using the spectroscopic classification system in the ischemia-reperfusion groups.

CONCLUSIONS

DRS could potentially be used intraoperatively for the assessment of bowel viability in real time. These preliminary findings suggest that DRS has the potential to reduce unnecessary resection of viable tissue or insufficient resection of nonviable tissues may reduce the mortality and morbidity rates of intestinal ischemia-reperfusion as acute mesenteric ischemia.

The damage control sequence in the elderly: Strategy, complexities, and outcomes

Traditional management in cases of exsanguinating abdominal trauma led to poor outcomes in critically injured patients. Because prolonged operations were not well tolerated due to the severe physiologic derangements, an abbreviated laparotomy began to be used. Patients were then resuscitated in the intensive care unit and brought back to the operating room once their physiology had been normalised. This approach has been termed the damage control sequence. Elderly trauma patients are susceptible to significant injury that may mandate a damage control sequence. For myriad reasons, including pre-existing medical conditions, decreased physiologic reserve, and the emergent nature of their injuries, the application of this management approach in the elderly is fraught with challenges. The purpose of this review is to enumerate the damage control sequence, describe the complexities of its use in the elderly, and discuss associated outcomes in this challenging patient population.

Near infrared spectroscopy (NIRS) of the thenar eminence in anesthesia and intensive care

Near infrared spectroscopy of the thenar eminence (NIRS_th) is a noninvasive bedside method for assessing tissue oxygenation. The NIRS probe emits light with several wavelengths in the 700- to 850-nm interval and measures the reflected light mainly from a predefined depth. Complex physical models then allow the measurement of the relative concentrations of oxy and deoxyhemoglobin, and thus tissue saturation (StO₂), as well as an approximation of the tissue hemoglobin, given as tissue hemoglobin index.

Here we review of current knowledge of the application of NIRS_th in anesthesia and intensive care.

We performed an analytical and descriptive review of the literature using the terms “near-infrared spectroscopy” combined with “anesthesia,” “anesthesiology,” “intensive care,” “critical care,” “sepsis,” “bleeding,” “hemorrhage,” “surgery,” and “trauma” with particular focus on all NIRS studies involving measurement at the thenar eminence.

We found that NIRS_th has been applied as clinical research tool to perform both static and dynamic assessment of StO₂. Specifically, a vascular occlusion test (VOT) with a pressure cuff can be used to provide a dynamic assessment of the tissue oxygenation response to ischemia. StO₂ changes during such induced ischemia-reperfusion yield information on oxygen consumption and microvasculatory reactivity. Some evidence suggests that StO₂ during VOT can detect fluid responsiveness during surgery. In hypovolemic shock, StO₂ can help to predict outcome, but not in septic shock. In contrast, NIRS parameters during VOT increase the diagnostic and prognostic accuracy in both hypovolemic and septic shock. Minimal data are available on static or dynamic StO₂ used to guide therapy.

Although the available data are promising, further studies are necessary before NIRS_th can become part of routine clinical practice.

How to assess intestinal viability during surgery: A review of techniques

Objective and quantitative intraoperative methods of bowel viability assessment are essential in gastrointestinal surgery. Exact determination of the borderline of the viable bowel with the help of an objective test could result in a decrease of postoperative ischemic complications. An accurate, reproducible and cost effective method is desirable in every operating theater dealing with abdominal operations. Numerous techniques assessing various parameters of intestinal viability are described by the studies. However, there is no consensus about their clinical use. To evaluate the available methods, a systematic search of the English literature was performed. Virtues and drawbacks of the techniques and possibilities of clinical application are reviewed. Valuable parameters related to postoperative intestinal anastomotic or stoma complications are analyzed. Important issues in the measurement and interpretation of bowel viability are discussed. To date, only a few methods are applicable in surgical practice. Further studies are needed to determine the limiting values of intestinal tissue oxygenation and flow indicative of ischemic complications and to standardize the methods.

Intraoperative assessment of microperfusion with visible light spectroscopy for prediction of anastomotic leakage in colorectal anastomoses

PURPOSE

Anastomotic leakage is associated with increased morbidity and mortality. However, there is no accurate tool to predict its occurrence. We evaluated the predictive value of visible light spectroscopy (VLS), a novel method to measure tissue oxygenation [saturated O(2) (StO(2) )], for anastomotic leakage of the colon and the rectum.

METHOD

Oxygen saturation in the bowel was measured in 77 colorectal resections. The anastomosis was between 2 and 30 cm (mean 13 cm) from the anal verge. The oxygen saturation was measured in the colon and rectum before and after anastomosis construction. This was compared with a reference measurement in the caecum. Data on postoperative complications were prospectively collected.

RESULTS

Anastomotic leakage occurred in 14 (18%) patients. When compared with a leaking anastomosis, normal anastomoses showed rising O(2) values during the operation (mean StO(2) 72.1 ± 9.0-76.7 ± 8.0 vs 73.9 ± 7.9-73.1 ± 7.4) (P ≤ 0.05). There were also higher StO(2) values in the caecum compared with those which ultimately leaked (73.6 ± 5.7 normal anastomoses, 69.6 ± 5.6 anastomotic leaks) (P ≤ 0.05). Both StO(2) values were predictive of anastomotic leakage.

CONCLUSION

Tissue oxygenation O(2) appears to be a potentially useful means of predicting anastomotic leakage after colorectal anastomosis.

Reduction of oxygenation and blood flow in pedicled bowel segments in the rat and its consequences for anastomotic healing

PURPOSE

Experimental studies indicate that perioperative hypoperfusion impairs anastomotic healing. In bowel surgery, the part of bowel that will be anastomosed is often pedicled, leaving the blood supply dependent on the marginal artery only. Little is known about the blood supply in such a segment, and whether anastomotic strength is affected when flow would be reduced. This study describes oxygenation and blood flow in pedicled bowel segments in the rat and investigates whether early anastomotic strength changes with variations in blood flow.

METHODS

In rats, pedicled segments were created in ileum and colon by successive ligation of the feeding arteries. Oxygenation and blood flow were measured in the distal part of this segment by use of near-infrared spectroscopy with indocyanine green as an intravascular tracer. In a second experiment, a short pedicled colonic segment was created and, after flow measurements, an anastomosis was constructed. Wound strength and hydroxyproline content were analyzed 2 and 5 days after operation.

RESULTS

After creation of a pedicled segment, the concentration of oxygenated hemoglobin decreased significantly. Blood flow also significantly decreased to even less than 10% of baseline. A very large variation was observed between animals, in particular, after ligation of the first arteries. The strength of colonic anastomoses was not significantly correlated with the blood flow in the pedicled segment before anastomotic construction.

CONCLUSIONS

The creation of a pedicled bowel segment greatly reduces tissue oxygenation and blood flow to its distal part. Such impaired perioperative flow does not significantly affect early wound strength after anastomotic construction.

Anastomotic leakage after low anterior resection for rectal cancer: facts, obscurity, and fiction

The subject of anastomotic leakage after low anterior resection (LAR) for rectal cancer remains controversial. Risk factors have been discussed in several studies but the findings are often inconclusive. This review evaluates these studies and separates the known risk factors into those that are well documented, those that are obsolete, and those that require further research. We searched the Medline and PubMed databases using the keywords: "leakage," "low anterior resection," "rectal cancer," "risk factors," and their combinations. There were no language or publication year restrictions. References in published papers were also reviewed. Each risk factor was evaluated and discussed separately. The evidence suggests that low anastomoses are more prone to leakage. Other well-documented risk factors are male sex, smoking, and preoperative malnutrition. Routine mobilization of the splenic flexure and the use of a J-pouch seem to reduce the leakage rate. The effect of preoperative chemo-radiotherapy is under scrutiny. The indications for a protective stoma remain debatable. Omentoplasty, bowel preparation, the use of a drain, and tumor stage do not seem to affect the leakage rate. The type of operation (open or laparoscopic) and anastomosis (hand-sewn or stapled) is not crucial.

Near-infrared spectroscopy to monitor peripheral blood flow perfusion

BACKGROUND

Non-invasive evaluation of peripheral perfusion may be useful in many contexts including peri-operative monitoring. We validated a novel non-invasive spectroscopy technique to assess peripheral perfusion. This method, which is based on the measurement of tissue saturation variations after an ischemic period, was compared to strain gauge plethysmography and radionuclide plethysmography. The technique uses near-infrared spectroscopy (NIRS) to determine the rate of change of forearm tissue saturation during reactive hyperemia.

METHODS

In a prospective crossover study, 25 subjects were simultaneously evaluated with NIRS and strain gauge plethysmography. Six baseline flow measurements were performed to assess the reproducibility of each method. Twenty-seven serial measurements were then made to evaluate flow variation during forearm reactive hyperemia.

RESULTS

Strain gauge and NIRS methods showed excellent reproducibility with intra-class correlation coefficients of 0.96 and 0.93, respectively.

CONCLUSION

The NIRS technique appears well suited for the non-invasive evaluation of limb perfusion.