Laser Doppler flowmetry is useful in the clinical management of small bowel transplantation. The Liver Transplant Group

Roxadustat promotes hypoxia-inducible factor-1α/vascular endothelial growth factor signalling to enhance random skin flap survival in rats

Random skin flaps have limited clinical application as a broad surgical reconstruction treatment because of distal necrosis. The prolyl hydroxylase domain-containing protein inhibitor roxadustat (RXD) enhances angiogenesis and reduces oxidative stress and inflammation. This study explored the function of RXD in the survival of random skin flaps. Thirty-six male Sprague-Dawley rats were randomly divided into low-dose RXD group (L-RXD group, 10 mg/kg/2 day), high-dose RXD group (H-RXD group, 25 mg/kg/2 day), and control group (1 mL of solvent, 1:9 DMSO:corn oil). The proportion of surviving flaps was determined on day 7 after surgery. Angiogenesis was assessed by lead oxide/gelatin angiography, and microcirculation blood perfusion was evaluated by laser Doppler flow imaging. Specimens in zone II were obtained, and the contents of superoxide dismutase (SOD) and malondialdehyde (MDA) were measured as indicators of oxidative stress. Histopathological status was evaluated with haematoxylin and eosin staining. The levels of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), and the inflammatory factors interleukin (IL)-1β, IL-6, and tumour necrosis factor-α (TNF-α) were detected by immunohistochemistry. RXD promoted flap survival and microcirculatory blood perfusion. Angiogenesis was detected distinctly in the experimental group. SOD activity increased and the MDA level decreased in the experimental group. Immunohistochemistry indicated that the expression levels of HIF-1α and VEGF were increased while the levels of IL-6, IL-1β, and TNF-α were decreased after RXD injection. RXD promoted random flap survival by reinforcing vascular hyperplasia and decreasing inflammation and ischaemia-reperfusion injury.

Impairment of Mesenteric Perfusion as a Marker of Major Bleeding in Trauma Patients

The majority of potentially preventable mortality in trauma patients is related to bleeding; therefore, early recognition and effective treatment of hemorrhagic shock impose a cardinal challenge for trauma teams worldwide. The reduction in mesenteric perfusion (MP) is among the first compensatory responses to blood loss; however, there is no adequate tool for splanchnic hemodynamic monitoring in emergency patient care. In this narrative review, (i) methods based on flowmetry, CT imaging, video microscopy (VM), measurement of laboratory markers, spectroscopy, and tissue capnometry were critically analyzed with respect to their accessibility, and applicability, sensitivity, and specificity. (ii) Then, we demonstrated that derangement of MP is a promising diagnostic indicator of blood loss. (iii) Finally, we discussed a new diagnostic method for the evaluation of hemorrhage based on exhaled methane (CH₄) measurement. Conclusions: Monitoring the MP is a feasible option for the evaluation of blood loss. There are a wide range of experimentally used methodologies; however, due to their practical limitations, only a fraction of them could be integrated into routine emergency trauma care. According to our comprehensive review, breath analysis, including exhaled CH₄ measurement, would provide the possibility for continuous, non-invasive monitoring of blood loss.

Analysis of Cumulative Fluid Balance Impact on the Stability of Gastrointestinal Tract Anastomosis

Anastomotic leakage is a serious postoperative complication following a low anterior resection of rectum. Current research in colorectal surgery focuses on searching for techniques which could minimize the risk of leakage. The main objective of this study was to evaluate the impact of cumulative fluid balance on microcirculatory changes at the anastomotic site.This experimental study used 15 domestic pigs; all of the animals underwent rectal resection. Then the animals were divided into three groups and received IV crystalloids at various rates, i.e. 5 ml/kg/h; 10 ml/kg/h; and 20 ml/kg/h. Large bowel micro-perfusion was measured using laser Doppler flowmetry during and following the surgical procedure.The experiments were successfully performed in all 15 cases. No animal died during the procedure or during the follow-up. We found no differences in micro-perfusion of the bowel between the experimental groups during the surgical procedure and during the follow-up period after the surgery. A significant decrease in micro-perfusion was observed after the transection of the inferior mesenteric artery in all the groups; again, no differences between the groups were observed.We did not confirm the original hypothesis that excessive load of IV crystalloids during the surgery would have a negative effect on bowel micro-perfusion and thus a negative effect on the healing of the anastomosis. However, laser Doppler flowmetry was found to have high accuracy in measuring tissue microcirculation and has the potential to be used in clinical practice.

The correlation between preputial blood flow and microvessel density in distal hypospadias: a prospective clinical study

OBJECTIVE

A prospective clinical study was designed to investigate the correlation between preputial blood flow (BF) and microvessel density (MVD).

PATIENTS AND METHODS

A total of 44 children were included in the study. The hypospadias group consisted of 16 children undergoing distal hypospadias repair, and the control group consisted of 28 age-matched healthy children undergoing circumcision. BFs were measured using a laser Doppler flowmeter on the most distal part of the dorsal prepuces, and then the tissue samples were harvested from the same location. They were immunostained with an antibody against CD31 in order to assay MVD. The statistical analyses were carried out using Student's t test and Pearson's correlation analysis.

RESULTS

The preputial MVD was found to be significantly decreased in the patients with hypospadias compared with the healthy children (33.95 ± 9.79 vs. 48.25 ± 10.08; p < 0.05), whereas there was no difference in terms of the BF (40.58 ± 16.16 vs. 33.09 ± 19.65; p > 0.05).

CONCLUSIONS

We found no correlation between the preputial MVD and BF in the present study. This result suggests that reduced preputial MVD does not have any influence on BF in distal hypospadias.

An in vivo investigation of photoplethysmographic signals and preliminary pulse oximetry estimation from the bowel using a new fiberoptic sensor

BACKGROUND

The continuous monitoring of splanchnic organ oxygen saturation could make the early detection of inadequate tissue oxygenation feasible, reducing the risk of hypoperfusion, severe ischemia, multiple organ failure, and, ultimately, death. Current methods for assessing splanchnic perfusion have not been widely accepted for use in the clinical care environment. In an attempt to overcome the limitations of the current techniques, a new fiberoptic photoplethysmographic (PPG)/pulse oximetry sensor was developed as a means of assessing splanchnic organ perfusion during surgery in humans.

METHODS

A new fiberoptic splanchnic pulse oximeter and an optically identical fiberoptic finger pulse oximeter have been developed. Simultaneous PPG signals and preliminary estimates of arterial oxygen saturation from the bowel (small and large) and finger were obtained in 17 patients (3 men and 14 women) undergoing open laparotomy.

RESULTS

Good quality PPG signals were obtained from the small and large bowel and from the finger in all patients (lower 95% confidence limit for the proportion was 0.64). Comparisons of blood oxygen saturation values acquired when using the splanchnic and the finger fiberoptic sensors and a commercial finger pulse oximeter indicated that there was no statistically significant difference between them (all P>0.454). A Bland and Altman plot of the difference between blood oxygen saturation values from the bowel fiberoptic pulse oximeter and the fiberoptic finger pulse oximeter against their mean showed that the limits of agreement between the 2 pulse oximeters were -3.8% and 4.2% for small bowel measurements, and -3.4% and 4.3% for large bowel measurements. The 95% prediction interval for the difference between the 2 devices was between -4.2% and 4.7%.

CONCLUSION

This study demonstrated that good quality PPG signals can be obtained from the bowel using a new fiberoptic sensor. Further evaluation is required to determine whether fiberoptic pulse oximetry of the bowel may provide a suitable method for monitoring splanchnic perfusion.

[Assessment of perioperative fluid balance]

Careful assessment of the fluid balance is required in the perioperative period since appropriate fluid therapy is essential for successful patient's outcome. Haemodynamic monitoring allows understanding the physiology of the circulation and changes of fluid balance in the perioperative period. This is diagnostic aid and guide for fluid replacement therapy. Patient's volume status is frequently assessed by different haemodynamic variables that could be targeted as the endpoints for fluid therapy and resuscitation. Fluid balance is the crucial factor in the maintenance of haemodynamic stability, tissue oxygenation and organ function. When the haemodynamic monitoring is applied in a rigorous and consistent manner, it reduces mortality and length of stay as well as costs incurred. There are a number of tests which describe the effectiveness of the invasive haemodynamic monitoring procedures usage. Since the pulmonary artery catheter (PAC) had been introduced into clinical practice it was considered as a golden standard for cardiac output measurements, haemodynamic and fluid balance assessment. Nevertheless, in previous 10 years new minimally invasive and noninvasive simple techniques for haemodynamic monitoring and patient's hydroelectricity status evaluation have been developed. They can replace PAC under different clinical circumstances and some of these techniques

Effects of dopexamine on the intestinal microvascular blood flow and leukocyte activation in a sepsis model in rats

INTRODUCTION

The administration of dopexamine may constitute a therapeutical option to improve hepatosplanchnic perfusion in sepsis. In order to verify this hypothesis, we administered dopexamine in an experimental sepsis model in rats.

METHODS

This prospective, randomized, controlled laboratory study was conducted in 42 Wistar rats. The animals were divided into 3 groups. Group 1 (CON group) served as control group. The Animals of groups 2 (LPS Group) and 3 received an endotoxin infusion (20 mg/kgfor 15 min). In addition, in group 3 (DPX group) dopexamine was administered 0.5 microg/kg/minover 4 hours. One half of the animals of each group underwent studies of intestinal microvascular blood flow (IMBF) using laser Doppler fluxmetry. In the other half an intravital microscopic evaluation of the leukocyte endothelium cell interaction in the intestinal microcirculation was performed. Functional capillary denstity (FCD) in the intestinal mucosaand the circular as well as the longitudinal muscle layer was estimated.

RESULTS

One hour after endotoxin challenge IMBF decreased significantly in the untreated LPS group to 51% compared to baseline (p<0.05). In DPX treated endotoxin animals we found significantly higher values at the level of CON group. The after endotoxin challenge impaired FCD was improved by dopexamine in the longitudinal (DPX + 33% vs. LPS; p <0.05) and in the circular muscle layer (DPX + 48% vs. LPS; p < 0.05) as a result of dopexamine administration. The administration of dopexamine reduced the count of firmly adherent leukocytes when compared to the untreated LPS group (-31%, p<0.05). TNF-alpha plasma levels were reduced by dopexamine infusion (LPS group 3637 +/- 553 pg/mL; DPXgroup 1933 +/- 201 pg/mL) one hour after endotoxin challenge.

CONCLUSIONS

The administration of dopexamine improved IMBF and FCD as parameters of intestinal microcirculation and reduced leukocyte activation as a parameter of inflammation in experimental sepsis.

Pyrrolidine dithiocarbamate reduces ischemia-reperfusion injury of the small intestine

AIM

To evaluate whether pyrrolidine dithiocarbamate (PDTC), an enhancer of HO production, attenuates intestinal IR injury.

METHODS

Eighteen male rats were randomly allocated into three groups: (a) sham; (b) IR, consisting of 30 min of intestinal ischemia, followed by 2-h period of reperfusion; and (c) PDTC treatment before IR. Intestinal microvascular perfusion (IMP) was monitored continuously by laser Doppler flowmetry. At the end of the reperfusion, serum samples for lactate dehydrogenase (LDH) levels and biopsies of ileum were obtained. HO activity in the ileum was assessed at the end of the reperfusion period.

RESULTS

At the end of the reperfusion in the IR group, IMP recovered partially to 42.5% of baseline (P<0.05 vs sham), whereas PDTC improved IMP to 67.3% of baseline (P<0.01 vs IR). There was a twofold increase in HO activity in PDTC group (2 062.66+/-106.11) as compared to IR (842.3+/-85.12) (P<0.001). LDH was significantly reduced (P<0.001) in PDTC group (585.6+/-102.4) as compared to IR group (1 973.8+/-306.5). Histological examination showed that the ileal mucosa was significantly less injured in PDTC group as compared with IR group.

CONCLUSION

Our study demonstrates that PDTC improves the IMP and attenuates IR injury of the intestine possibly via HO production. Additional studies are warranted to evaluate the clinical efficacy of PDTC in the prevention of IR injury of the small intestine.

Ischaemic preconditioning improves microvascular perfusion and oxygenation following reperfusion injury of the intestine

BACKGROUND

Ischaemia-reperfusion (IR) injury of the intestine occurs commonly during abdominal surgery. Ischaemic preconditioning (IPC) provides a way of protecting the organ from damage inflicted by IR. This study was designed to evaluate the beneficial effect of IPC, focusing on the intestinal microcirculation and oxygenation in intestinal IR injury.

METHODS

Rats were allocated to three groups. Animals in the IR and IPC groups underwent 30 min of intestinal ischaemia followed by 2 h of reperfusion. In the IPC group this was preceded by 10 min of ischaemia and 10 min of reperfusion. Animals in the third group underwent laparotomy but no vascular occlusion. Intestinal microvascular perfusion, oxygenation and portal venous blood flow (PVF) were monitored continuously. At the end of the reperfusion period, blood samples were obtained for measurement of lactate dehydrogenase (LDH) and biopsies of ileum for histological evaluation.

RESULTS

: IPC improved intestinal microvascular perfusion and tissue oxygenation significantly at the end of the reperfusion period (P < 0.001). PVF improved significantly in the IPC compared with the IR group (P = 0.005). The serum LDH concentration was significantly lower in the IPC than the IR group (mean(s.e.m.) 667.1(86.8) versus 1973.8(306.5) U/l; P < 0.001) Histological examination showed that ileal mucosa was significantly less injured in the IPC group.

CONCLUSIONS

This study demonstrated that IPC improves intestinal microvascular perfusion and oxygenation.

Perioperative fluid management and clinical outcomes in adults

The administration of IV fluid to avoid dehydration, maintain an effective circulating volume, and prevent inadequate tissue perfusion should be considered, along with the maintenance of sleep, pain relief, and muscular relaxation, a core element of the perioperative practice of anesthesia. Knowledge of the effects of different fluids has increased in recent years, and the choice of fluid type in a variety of clinical situations can now be rationally guided by an understanding of the physicochemical and biological properties of the various crystalloid and colloid solutions available. However, there are few useful clinical outcome data to guide this decision. Deciding how much fluid to give has historically been more controversial than choosing which fluid to use. A number of clinical studies support the notion that an approach based on administering fluids to achieve maximal left ventricular stroke volume (while avoiding excess fluid administration and consequent impairment of left ventricular performance) may improve outcomes. In this article, we review the available fluid types and strategies of fluid administration and discuss their relationship to clinical outcomes in adults.

Laser-Doppler flowmetry is reliable for early diagnosis of small-bowel acute rejection in the mouse

The purpose of the study was to investigate intestinal mucosal perfusion in mouse small-bowel transplantation (SBT), using laser-Doppler flowmetry. Heterotopic SBT was performed in syngeneic and allogeneic combinations. Mucosal perfusion was measured both in the native and in the grafted intestine at time of surgery and at 1, 3, 6, and 8 days postoperatively. Histology specimens were obtained at the same time and graded for rejection. No rejection was seen in the syngeneic group at any of the time points studied. The allografts displayed significant decreased mucosal perfusion on postoperative days 3, 6, and 8. Rejection was histologically evident on postoperative days 6 and 8. Laser-Doppler perfusion in the rejecting intestinal allograft was decreased before onset of histological features of rejection. Mucosal blood flow measured by laser-Doppler could be used as an early indicator of acute rejection in SBT.

Surgery of the small intestine

The small intestine is the portal of entry of virtually all nutrients and is also the site of diverse inflammatory and neoplastic diseases. This field has recently attracted intense excitement as a result of novel clinical and experimental techniques, combined modality therapies, and basic science applications. This review will highlight important clinical advances in surgery for Crohn disease, short bowel syndrome, transplantation, trauma, and polyposis. Promising experimental approaches, novel methods of clinical assessment, and multimodality treatment will also be considered.

Small bowel transplantation: selection criteria, operative techniques, advances in specific immunosuppression, prognosis

Intestinal transplantation is now an accepted therapy for intestinal failure when parenteral nutrition therapy cannot be tolerated. During the past year, evidence has been provided indicating that neither stomach nor colon need to be included in the transplant, even if a primary motility disorder is the indication for surgery. The liver should be included in the composite allograft when there are clinical indications of portal hypertension resulting from parenteral nutrition associated cholestasis. When liver disease develops, operations intended to improve gut function should be avoided in preference of early listing for transplantation. During the past year, initial attempts at adult to child intestinal transplantation were carried out with some success; reduction in the diameter of the adult donor bowel may not be uniformly necessary. New immunosuppressive therapies have been employed recently, but few have been subjected to peer review. Experimental models have clarified the pathology, if not the immunobiology, of chronic intestinal allograft rejection and the ability of the liver to promote tolerance of a cotransplanted intestinal allograft. Treatment of posttransplant lymphoproliferative disease has been augmented by the use of anti-CD 20 antibody that targets Epstein-Barr virus infected B-cells for destruction with high specificity.