Mucosal protection from intestinal ischemia-reperfusion reduces oxidant injury to the lung

Luminal Delivery of Pectin-Modified Oxygen Microbubbles Mitigates Rodent Experimental Intestinal Ischemia

INTRODUCTION

Ischemic gut injury is common in the intensive care unit, impairs gut barrier function, and contributes to multiorgan dysfunction. One novel intervention to mitigate ischemic gut injury is the direct luminal delivery of oxygen microbubbles (OMB). Formulations of OMB can be modified to control the rate of oxygen delivery. This project examined whether luminal delivery of pectin-modified OMB (OMBp5) can reduce ischemic gut injury in a rodent model.

METHODS

The OMBp5 formulation was adapted to improve delivery of oxygen along the length of small intestine. Adult Sprague-Dawley rats (n = 24) were randomly allocated to three groups: sham-surgery (SS), intestinal ischemia (II), and intestinal ischemia plus luminal delivery of OMBp5 (II + O). Ischemia-reperfusion injury was induced by superior mesenteric artery occlusion for 45 min followed by reperfusion for 30 min. Outcome data included macroscopic score of mucosal injury, the histological score of gut injury, and plasma biomarkers of intestinal injury.

RESULTS

Macroscopic, microscopic data, and intestinal injury biomarker results demonstrated minimal intestinal damage in the SS group and constant damage in the II group. II + O group had a significantly improved macroscopic score throughout the gut mucosa (P = 0.04) than the II. The mean histological score of gut injury for the II + O group was significantly improved on the II group (P ≤ 0.01) in the proximal intestine only, within 30 cm of delivery. No differences were observed in plasma biomarkers of intestinal injury following OMBp5 treatment.

CONCLUSIONS

This proof-of-concept study has demonstrated that luminal OMBp5 decreases ischemic injury to the proximal small intestine. There is a need to improve oxygen delivery over the full length of the intestine. These findings support further studies with clinically relevant end points, such as systemic inflammation and vital organ dysfunction.

Intraluminal oxygen mitigates acute mesenteric ischaemia: a systematic review of methods and outcomes in animal studies

BACKGROUND

Acute Mesenteric Ischaemic (AMI) is a rare condition with significant morbidity and mortality. Many causes of AMI exist, which usually begin with mucosal injury. Onset is insiduous and there is frequent diagnostic delay. Current treatments can only control established injury and prevent propagation, hence new interventions are needed. The prevention and treatment of AMI by intraluminal delivery of oxygen has yet to be investigated in the clinical setting. This article aims to systemically review experimental studies investigating this novel therapy.

METHODS

Following the PRISMA guidelines, searches of PubMed and Ovid MEDLINE databases were performed up to June 2022. Two independent investigators extracted the data.

RESULTS

There were 20 experimental studies, 16 of which used an occlusive ischaemia reperfusion model. Six different formulations were used to deliver intraluminal oxygen, with perflurocarbon being the most common. Studies consistently showed local and systemic benefits. Intraluminal oxygen therapy improved histological severity of mucosal injury in all studies when oxygen was delivered during the ischaemia phase, but could cause harm if given during the reperfusion phase. Improvement was also demonstrated in endpoints assessing intestinal function, biomarkers of intestinal damage, measures of systemic physiological derangement and mortality.

CONCLUSION

Intraluminal oxygenation appears to be an effective treatment for AMI. There remain significant questions regarding optimal timing and delivery formulation before clinical translation of this treatment strategy.

Mini-review: Perfluorocarbons, Oxygen Transport, and Microcirculation in Low Flow States: in Vivo and in Vitro Studies

The in vivo study of microvascular oxygen transport requires accurate and challenging measurements of several mass transfer parameters. Although recommended, blood flow and oxygenation are typically not measured in many studies where treatments for ischemia are tested. Therefore, the aim of this communication is to briefly review cardinal aspects of oxygen transport, and the effects of perfluorocarbon (PFC) treatment on blood flow and oxygenation based mostly on studies performed in our laboratory. As physiologically relevant events in oxygen transport take place at the microvascular level, we implemented the phosphorescence quenching technique coupled with noninvasive intravital videomicroscopy for quantitative evaluation of these events in vivo. Rodent experimental models and various approaches have been used to induce ischemia, including hemorrhage, micro- and macroembolism, and microvessel occlusion. Measurements show decrease in microvascular blood flow as well as intravascular and tissue oxygen partial pressure (PO2) after these procedures. To minimize or reverse the effects of ischemia and hypoxia, artificial oxygen carriers such as different PFCs were tested. Well-defined endpoints such as blood flow and tissue PO2 were measured because they have significant effect on tissue survival and outcome. In several cases, enhancement of flow and oxygenation could be demonstrated. Similar results were found in vitro: PFC emulsion mixed with blood (from healthy donors and sickle cell disease patients) enhanced oxygen transport. In summary, PFCs may provide beneficial effects in these models by mechanisms at the microvascular level including facilitated diffusion and bubble reabsorption leading to improved blood flow and oxygenation.

Effects of hyperbaric oxygen and iloprost on intestinal ischemia-reperfusion induced acute lung injury

Purpose

To research the effects of iloprost (IL) and hyperbaric oxygen (HBO) combination treatment on lung injury and on tumor necrosis factor alpha (TNF-α), myeloperoxidase (MPO), malondialdehyde (MDA), and soluble intercellular adhesion molecule-1 (sICAM-1) levels after tissue or organ ischemia-reperfusion, and on ischemia-reperfusion induced lung neutrophil sequestration.

Methods

Forty white New Zealand rabbits were assigned randomly into 5 groups: HBO, IL, HBO+IL, control, and sham groups. TNF-α values were checked before ischemia, in the 1st hour of ischemia and in the 1st and 4th hours of reperfusion, also at the end of reperfusion period, plasma and tissue MPO values, MDA values, and sICAM-1 levels were detected. After sacrifice, the degree of lung injury was determined by histopathological examination.

Results

Compared to the control group all therapy groups showed a drastically meaningful reduction in TNF-α increase in 1, 2, and 4 hours. Plasma and lung MDA, MPO, and sICAM-1 levels were significantly lower in IL, HBO, HBO+IL, and sham groups compared with the control group. IL and/or HBO suppressed MDA and MPO increase in the lung tissue and in plasma. Additionally, histopathological score was significantly lower in HBO, IL, HBO+IL, and sham groups than that of the control group.

Conclusion

Both HBO and IL therapy have a beneficial effect by causing a meaningful reduction in TNF-α production, MPO, MDA, sICAM-1 levels and pulmonary neutrophil sequestration; which play a role, especially, in ischemia reperfusion induced lung damage.

Sevoflurane ameliorates intestinal ischemia-reperfusion-induced lung injury by inhibiting the synergistic action between mast cell activation and oxidative stress

Preconditioning with sevoflurane (SEV) can protect against ischemia-reperfusion injury in several organs, however, the benefits of SEV against acute lung injury (ALI), induced by intestinal ischemia-reperfusion (IIR), and the underlying mechanisms remain to be elucidated. The present study was designed to investigate the effects of SEV preconditioning on IIR-mediated ALI and the associated mechanisms in a rat model. Female Sprague-Dawley rats treated with 2.3% SEV or apocynin (AP), an inhibitor of NADPH oxidase, were subjected to 75 min superior mesenteric artery occlusion followed by 2 h reperfusion in the presence or absence of the mast cell degranulator compound 48/80 (CP). SEV and AP were observed to downregulate the protein expression levels of p47^phox and gp91^phox in the lungs of normal rats. IIR resulted in severe lung injury, characterized by significant increases in pathological injury scores, lung wet/dry weight ratio, protein expression levels of p47^phox, gp91^phox and ICAM-1, the presence of hydrogen peroxide, malondydehyde and interleukin-6, and the activity of myeloperoxidase. In addition, significant reductions were observed in the expression of prosurfactant protein C, accompanied by an increase in MC degranulation, demonstrated by significant elevations in the number of mast cells, expression levels of tryptase and the concentration of β-hexosaminidase. These changes were further augmented in the presence of CP. In addition, SEV and AP preconditioning significantly alleviated the above alterations induced by IIR alone or in combination with CP. These findings suggested that SEV and AP attenuated IIR-induced ALI by inhibiting NADPH oxidase and the synergistic action between oxidative stress and mast cell activation.

Protective effects of hyperbaric oxygen and iloprost on ischemia/reperfusion-induced lung injury in a rabbit model

Background

The role of multiorgan damage in the mortality caused by ischemic limb injury is still not clarified. The objective of this study was to examine the potential protective effects of hyperbaric oxygen (HBO) and iloprost (IL) therapy on lung damage induced by limb ischemia/reperfusion injury in a rabbit model, using both biochemical and histopathological aspects.

Methods

Forty New Zealand white rabbits were randomly allocated into one of five study groups: HBO group (single session of HBO treatment); IL group (25 ng/kg/min infusion of IL); HBO + IL group (both HBO and IL); Control group (0.9% saline only); and a sham group. Acute hind limb ischemia-reperfusion was established by clamping the abdominal aorta for 1 h. HBO treatment and IL infusion were administrated during 60 min of ischemia and 60 min of reperfusion period. Blood pH, partial pressure of oxygen, partial pressure of carbon dioxide and levels of bicarbonate, sodium, potassium, creatine kinase, lactate dehydrogenase, and tumor necrosis factor alpha were determined at the end of the reperfusion period. Malondialdehyde was measured in the plasma and lung as an indicator of free radicals. After sacrifice, left lungs were removed and histopathological examination determined the degree of lung injury.

Results

In the control group, blood partial pressure of oxygen and bicarbonate levels were significantly lower and creatine kinase, lactate dehydrogenase, malondialdehyde and tumor necrosis factor-α levels were significantly higher than those of the HBO group, IL group, HBO + IL group and sham group. Similarly, the malondialdehyde levels in the lung tissue and plasma levels were significantly lower in the treatment groups compared with the control group. The extent of lung injury according to the histological findings was significantly higher in the control group.

Conclusions

These results suggest that both HBO and IL therapies and their combination might be effectively used in the prevention of lung injury after ischemia/reperfusion injury of the lower extremities.

Anti-inflammatory and antioxidant effects of infliximab on acute lung injury in a rat model of intestinal ischemia/reperfusion

The purpose of this study was to investigate the role of infliximab on acute lung injury induced by intestinal ischemia/reperfusion (I/R). A total of 30 male Wistar albino rats were divided into three groups: sham, I/R and I/R+ infliximab; each group contain 10 animals. Sham group animals underwent laparotomy without I/R injury. After I/R groups animals underwent laparotomy, 1 h of superior mesenteric artery ligation were followed by 1 h of reperfusion. In the infliximab group, 3 days before I/R, infliximab (3 mg/kg) was administered by intravenously. All animals were sacrificed at the end of reperfusion and lung tissues samples were obtained for biochemical and histopathological investigation in all groups. To date, no more biochemical and histopathological changes on intestinal I/R injury in rats by infliximab treatment have been reported. Infliximab treatment significantly decreased the elevated tissue malondialdehyde levels and increased of reduced superoxide dismutase, and glutathione peroxidase enzyme activities in lung tissues samples. Intestinal I/R caused severe histopathological injury including edema, hemorrhage, increased thickness of the alveolar wall and a great number of inflammatory cells that infiltrated the interstitium and alveoli. Infliximab treatment significantly attenuated the severity of intestinal I/R injury. Furthermore, there is a significant reduction in the activity of inducible nitric oxide synthase and arise in the expression of surfactant protein D in lung tissue of acute lung injury induced by intestinal I/R with infliximab therapy. It was concluded that infliximab treatment might be beneficial in acute lung injury, therefore, shows potential for clinical use. Because of its anti-inflammatory and antioxidant effects, infliximab pretreatment may have protective effects in acute lung injury induced by intestinal I/R.

Protective effect of curcumin on acute lung injury induced by intestinal ischaemia/reperfusion

The aim of this study is to evaluate the role of curcumin on acute lung injury induced by intestinal ischaemia/reperfusion (I/R). A total of 30 male Wistar albino rats were divided into 3 groups: sham, I/R, and I/R + curcumin; each group contains 10 animals. Sham group animals underwent laparotomy without I/R injury. After I/R groups animals underwent laparotomy, 1 h of superior mesenteric artery ligation were followed by 1 h of reperfusion. In the curcumin group, 3 days before I/R, curcumin (100 mg/kg) was administered by gastric gavage. All animals were killed at the end of reperfusion and lung tissue samples were obtained for biochemical and histopathological investigation in all groups. To date, no more biochemical and histopathological changes on intestinal I/R injury in rats by curcumin treatment have been reported. Curcumin treatment significantly decreased the elevated tissue malondialdehyde levels and increased reduced superoxide dismutase, and glutathione peroxidase enzyme activities in lung tissue samples. Intestinal I/R caused severe histopathological injury including oedema, haemorrhage, increased thickness of the alveolar wall, and infiltration of inflammatory cells into alveolar spaces. Curcumin treatment significantly attenuated the severity of intestinal I/R injury. Furthermore, there is a significant reduction in the activity of inducible nitric oxide synthase and increase in the expression of surfactant protein D in lung tissue of acute lung injury induced by intestinal I/R with curcumin therapy. It was concluded that curcumin treatment may have beneficial effects in acute lung injury, and therefore has potential for clinical use.

Ginkgo biloba extract (EGb 761) attenuates lung injury induced by intestinal ischemia/reperfusion in rats: Roles of oxidative stress and nitric oxide

AIM: To investigate the effect of ginkgo biloba extract (EGb 761) on lung injury induced by intestinal ischemia/reperfusion (II/R).

METHODS: The rat model of II/R injury was produced by clamping the superior mesenteric artery for 60 min followed by reperfusion for 180 min. The rats were randomly allocated into sham, II/R, and EGb +II/R groups. In EGb +II/R group, EGb 761 (100 mg/kg per day) was given via a gastric tube for 7 consecutive days prior to surgery. Rats in II/R and sham groups were treated with equal volumes of the vehicle of EGb 761. Lung injury was assessed by light microscopy, wet-to-dry lung weight ratio (W/D) and pulmonary permeability index (PPI). The levels of malondialdehyde (MDA) and nitrite/nitrate (NO₂^-/NO₃^-), as well as the activities of superoxide dismutase (SOD) and myeloperoxidase (MPO) were examined. Western blot was used to determine the expression of inducible nitric oxide synthase (iNOS).

RESULTS: EGb 761 markedly improved mean arterial pressure and attenuated lung injury, manifested by the improvement of histological changes and significant decreases of pulmonary W/D and PPI (p < 0.05 or 0.01). Moreover, EGb 761 markedly increased SOD activity, reduced MDA levels and MPO activity, and suppressed NO generation accompanied by down-regulation of iNOS expression (p < 0.05 or 0.01).

CONCLUSION: The results indicate that EGb 761 has a protective effect on lung injury induced by II/R, which may be related to its antioxidant property and suppressions of neutrophil accumulation and iNOS-induced NO generation. EGb 761 seems to be an effective therapeutic agent for critically ill patients with respiratory failure related to II/R.

Acute renal failure: much more than a kidney disease

Acute renal failure is a frequent clinical problem with an increasing incidence, an unacceptably high mortality rate that has not improved in more than 40 years, and no specific treatment, yet renal failure is not the usual cause of death. The role of inflammation has been documented in both acute renal injury and cardiac dysfunction. Several investigators have shown that congestive heart failure is associated with increased mortality in patients with acute renal failure. This article reviews some of the cardiac and other distant organ effects of acute renal injury that may be important in the morbidity and mortality observed clinically. Cardiac changes after experimental renal ischemia include cytokine induction, leukocyte infiltration, cell death by apoptosis, and impaired function. I propose that the extrarenal effects of kidney injury must be considered in designing therapies. Acute renal failure has systemic consequences and must be thought of as more than a kidney disease.

Surgical manipulation of the intestine and distant organ damage—protection by oral glutamine supplementation

BACKGROUND

The intestine is increasingly recognized as a primary effector of distant organ damage, such as the lung, after any abdominal surgery. Earlier studies have shown that surgical manipulation of the intestine induces generation of reactive oxygen species in the intestine, resulting in mucosal and lung damage. Because glutamine is preferentially used by the small intestine as an energy source, this study examined the effect of glutamine and glutamic acid on intestinal and lung damage after surgical manipulation.

METHODS

Controls and rats were pretreated for 7 days with 2% glutamine or glutamic acid, or the isonitrogenous amino acids glycine or alanine in the diet and subjected to surgical manipulation of the intestine. The intestine and lung were assessed for damage, and protection offered by various amino acids was studied.

RESULTS

Surgical manipulation resulted in oxidative stress in the intestine as evidenced by increased xanthine oxidase activity and decreased antioxidant status. Enterocyte mitochondria were also functionally impaired with altered calcium flux, decreased respiratory control ratio, and increased swelling. Gut manipulation also resulted in neutrophil infiltration and oxidative stress in the lung as assessed by an increase in myeloperoxidase activity, lipid peroxidation, and antioxidant status. Glutamine or glutamic acid supplementation for 7 days before surgical manipulation showed a protective effect against the intestinal and lung damage.

CONCLUSIONS

This study suggests that preoperative enteral glutamine or glutamic acid supplementation attenuates intestinal and lung damage in rats during surgical manipulation and that this effect might offer protection from postsurgical complications.

Hypoxemic reperfusion after 120 mins of intestinal ischemia attenuates the histopathologic and inflammatory response *

OBJECTIVE

It has been suggested that reactive oxygen species play a pivotal role in the initial organ-tissue injury during reperfusion, eliciting inflammatory reaction and multiple organ failure. It was investigated if hypoxemic reperfusion attenuates tissue injury and inflammatory response.

DESIGN

Randomized animal study.

SETTING

Medical school laboratory.

SUBJECTS

Twenty-five male pigs weighing 25-28 kg.

INTERVENTIONS

Pigs were subjected to 120 mins of intestinal ischemia by clamping the superior mesenteric artery. Upon declamping, the animals were randomly assigned to receive either hypoxemic reperfusion (HR group, n = 9) reperfused with a Pao2 = 30-35 or normoxemic reperfusion (control group, n = 16) reperfused with a Pao2 = 100 mm Hg for 120 mins. Fluids without inotropes were given to combat circulatory shock during reperfusion.

MEASUREMENTS AND MAIN RESULTS

Portal blood and intestinal and lung biopsies were collected at baseline, end of ischemia, and end of reperfusion. Histopathologic changes were scored, and interleukin-1beta, qualitative Limulus amebocyte, lysate test, and Pao2/Fio2 were measured. Eight of 16 animals of the control group and seven of nine of the HR group survived (p = .22). At the end of reperfusion, the intestinal (p = .004) and lung (p = .028) pathologic scores were lower in the HR group compared with controls. The only significant difference in concentration of interleukin-1beta in the portal blood between the two animal groups occurred 120 mins after reperfusion (p = .006). The number of HR animals with a positive Limulus test was significantly smaller compared with controls at 60 (p = .041) and 120 (p = .07) mins of reperfusion. During the period of ischemia, the Pao2/Fio2 decreased similarly in the control and HR group, whereas after 120 mins of reperfusion the rate was significantly higher in the HR group.

CONCLUSIONS

Hypoxemic reperfusion represents an intervention that may attenuate the triggering of multifactorial cascade and organ tissue injury.

Clinical potential of nonhemoglobin oxygen therapeutics in cardiac and general surgery

Significant efforts have been made over the past 70 years to find a solution that could substitute for blood. Over the years, the focus has shifted to developing a solution capable of delivering oxygen to the tissues. Fluorocarbons (FC) are highly inert solutions with a high solubility for all gases, making them a prime candidate to become such an oxygen delivery agent. Although clinical research efforts into the use of these agents as substitutes for blood transfusions continue at present, the rapid disappearance of emulsified FCs from the vascular space and accumulation in the liver and spleen may well limit their usefulness as transfusion substitutes. Because of their ability to dissolve significant quantities of oxygen and carbon dioxide, these agents may be more attractive as oxygen delivery agents during periods of local or global organ ischemia, including preservation of organs for transplantation. FCs have also been tested in animal models of cardiopulmonary bypass, and may be efficacious in adsorbing the gases present in air emboli. Recently a second class of oxygen therapeutics (allosteric modifiers) has been developed, and these agents enhance oxygen delivery by shifting the oxygen dissociation curve to the right, thus increasing tissue PO(2). Allosteric modifiers have been shown to effectively shift the p50 of hemoglobin 10mm Hg at clinically relevant dosages, and have been shown (in animal models) to reduce cerebral infarct size following carotid ligation and to improve myocardial performance following myocardial ischemia. Despite significant research efforts, however, none of the solutions under development are currently approved for clinical use by the Food and Drug Administration, with the exception of myocardial contrast imaging agents.

Distant effects of experimental renal ischemia/reperfusion injury

Acute renal failure results in significant morbidity and mortality, yet renal failure is not the usual cause of death in the clinical situation. We have previously reported systemic increases in the inflammatory mediators tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) after renal ischemia in the mouse. In the present study, an animal model of bilateral renal ischemia was used to test the hypothesis that cytokines released with renal ischemia have effects on other organ systems. Increased levels of immunoreactive TNF-alpha and IL-1 and intercellular adhesion molecule-1 mRNA were found in the heart after renal ischemia in the rat. This was accompanied by increases in myeloperoxidase activity, an index of tissue leukocyte infiltration, in the heart as well as the liver and lung. Functional changes in the heart 48 h after renal ischemia included increases in left ventricular end diastolic diameter, left ventricular end systolic diameter, and decreased fractional shortening by echocardiography. Evidence of apoptosis of cardiac cells was also found 48 h after an abbreviated period of renal ischemia insufficient to induce azotemia but not bilateral nephrectomy (which resulted in significant renal failure), suggesting that renal ischemia but not uremia is necessary for the apoptosis observed. It was also found that blocking the action of TNF-alpha limited cardiac apoptosis. Renal ischemia results in distant effects and the alterations observed in the heart may be important in the morbidity and mortality observed clinically.

Heat preconditioning prevents oxidative stress-induced damage in the intestine and lung following surgical manipulation

BACKGROUND

The intestine is increasingly recognized as a primary effector of distant organ damage, such as lung, following abdominal surgery. Surgical manipulation of the intestine generates oxygen free radicals resulting in mucosal damage. Heat preconditioning has been proposed to prevent various stress-induced alterations in cells and tissues, including oxidative stress. This study examined the effect of heat preconditioning on oxidative stress-induced damage to the intestine and lung, following surgical manipulation.

METHODS

Control rats and rats pretreated with heat were subjected to surgical manipulation by opening the abdominal wall and handling the intestine as done during laparotomy. Intestine and lung were assessed for damage by histology and markers of oxidative stress.

RESULTS

Surgical manipulation resulted in ultrastructural changes in the intestine. Biochemical alterations in the enterocytes were evident, with increased xanthine oxidase activity resulting in production of superoxide anion and with a decrease in antioxidant status. Gut manipulation also resulted in neutrophil infiltration and oxidative stress in the lung as assessed by histology, myeloperoxidase activity, lipid peroxidation and antioxidant status. Heat conditioning before surgical manipulation had a protective effect against this intestinal and lung damage.

CONCLUSION

This study suggests that mild whole-body hyperthermia before surgery might offer protection from postoperative complications.

Surgical manipulation of the small intestine and its effect on the lung

BACKGROUND

Surgical manipulation of the intestine results in generation of oxygen free radicals leading to mucosal damage as evidenced by ultrastructural and biochemical changes. It is likely that the gut-derived mediators can bring about damage to distant organs such as the lung.

METHODS

Surgical manipulation of the gut was performed by opening the abdominal wall and handling the intestine. Lung damage was assessed by histology, markers of oxidative stress, and protein content in bronchoalveolar lavage fluid. Protection offered by pretreatment with various compounds such as allopurinol, L-arginine, quinacrine, and indomethacin was also studied.

RESULTS

Gut manipulation resulted in neutrophil infiltration, oxidative stress, and permeability changes in the lung and these changes were maximum 30 and 60 min following surgical manipulation, which recovered with time and reversed to normal by 24 h. Prior treatment with inhibitors of xanthine oxidase, phospholipase A(2), or cyclooxygenase showed a protective effect against lung damage.

CONCLUSION

This study has shown that laparotomy and intestinal handling result in distant organ (lung) damage which is probably brought about by neutrophil infiltration and oxidative stress on the lung. This is likely mediated by compounds generated in the intestine and transported into the systemic circulation since inhibition of generation of chemical mediators in the intestine offers protection against lung damage.

Intestinal energy metabolism after ischemia-reperfusion: Effects of moderate hypothermia and perfluorocarbons

PURPOSE

This study investigated the roles of moderate hypothermia and extraluminal oxygenated perfluorcarbon (PFC) on intestinal metabolism after ischemia-reperfusion.

METHODS

A model of 30-minute intestinal ischemia followed by 60 minutes of reperfusion was used. The animals were maintained at either normothermia (36.5 to 37.5 degrees C) or moderate hypothermia (31 to 32 degrees C). Four groups of adult rats were studied (n = 8 per group): (A) sham at normothermia, (B) ischemia-reperfusion at normothermia, (C) ischemia-reperfusion at hypothermia and, (D) ischemia-reperfusion with extraluminal oxygenated PFC perfusion during ischemia at normothermia. Intestinal phosphocreatine, ATP and lactate levels were measured. Histologic changes in the intestine were evaluated.

RESULTS

Intestinal ischemia-reperfusion at normothermia caused a marked reduction in phosphocreatine and ATP with an increase in lactate. Moderate hypothermia exerted beneficial effects by attenuating the depletion of high-energy phosphates and the elevation of lactate. Extraluminal PFC perfusion during ischemia failed to produce a protective effect on high-energy phosphates, although it reduced lactate accumulation. Moderate hypothermia significantly decreased the degree of mucosal damage.

CONCLUSIONS

Whole-body moderate hypothermia protects the small intestine from reperfusion injury as measured both biochemically and histologically. Extraluminal oxygenated PFC administration during ischemia did not protect the intestine from reperfusion injury in this model.

Peritoneal lavage with oxygenated perfluorochemical preserves intestinal mucosal barrier function after ischemia-reperfusion and ameliorates lung injury

OBJECTIVE

To evaluate the effect of peritoneal lavage with an oxygenated perfluorochemical (PFC) on intestinal ischemia-reperfusion injury (IIR), we assessed intestinal barrier function in terms of bacterial translocation and endotoxemia, morphologic changes, and changes of intestinal luminal pH in rats subjected to IIR. We also examined lung injury after IIR to test the effect of oxygenated PFC lavage on remote organ failure.

DESIGN

Prospective, randomized, and controlled animal study.

SETTING

Laboratory of a university hospital.

SUBJECT

Male Sprague-Dawley rats.

INTERVENTIONS

Rats were subjected to ischemia by clipping the superior mesenteric artery. Reperfusion was achieved by release of the clip. Lavage of the abdominal cavity was performed by inflow and outflow of oxygenated PFC solution during ischemia.

RESULTS

Rats undergoing peritoneal lavage with oxygenated PFC (PFC group) showed significantly better survival after IIR. The frequency of bacterial translocation and the endotoxin concentration in superior mesenteric venous blood were significantly lower in the PFC group. Luminal acidosis also was alleviated in the PFC group. Furthermore, PFC lavage preserved the intestinal mucosal architecture and inhibited interstitial edema and infiltration of inflammatory cells in the lungs.

CONCLUSION

We conclude that peritoneal lavage with oxygenated PFC protects the intestinal mucosa and maintains mucosal barrier function after IIR. Preservation of the intestinal mucosa ameliorates lung injury after IIR.

Transabdominal oxygenation using perfluorocarbons

PURPOSE

Evaluation of the intraabdominal (intraperitoneal and intraluminal) administration of oxygen-saturated perfluorocarbon on both portal and arterial blood oxygenation.

METHODS

Eight male rabbits were divided into the test (n = 5) and control (n = 3) groups. Each underwent intrajejunal, intraperitoneal, and intravascular (artery, portal vein) catheter placements along with ligation of the duodenum and the terminal ileum under general anesthesia. The test group received oxygen-saturated perfluorotripropylamine (FTPA), and the control group received oxygen desaturated FTPA. The oxygen delivery was assessed by serial blood gas measurements before and after the administration of FTPA.

RESULTS

The administration of oxygen-saturated FTPA significantly increased the partial pressure of oxygen within both the arterial and the portal venous blood (PaO2, PpVO2) without significant changes in PCO2 values. Oxygen desaturated FTPA failed to show any effects on blood gas values. Compared with oxygen desaturated FTPA, oxygen-saturated FTPA increased PaO2, PpVO2, and oxygen saturation (artery, portal vein) significantly at some, but not all of the time-points measured.

CONCLUSIONS

The intraabdominal administration of saturated FTPA improved both the portal venous and the arterial oxygenation. This new mode of oxygenation may be helpful as an adjunct to conventional oxygen delivery systems.