Gut ischemia, oxidative stress, and bacterial translocation in elevated abdominal pressure in rats

Impact of Standard Versus Low Pneumoperitoneum Pressure on Peritoneal Environment in Laparoscopic Cholecystectomy. Randomized Clinical Trial

BACKGROUND

High CO 2 pneumoperitoneum pressure during laparoscopy adversely affects the peritoneal environment. This study hypothesized that low pneumoperitoneum pressure may be linked to less peritoneal damage and possibly to better clinical outcomes.

MATERIALS AND METHODS

One hundred patients undergoing scheduled laparoscopic cholecystectomy were randomized 1:1 to low or to standard pneumoperitoneum pressure. Peritoneal biopsies were performed at baseline time and 1 hour after peritoneum insufflation in all patients. The primary outcome was peritoneal remodeling biomarkers and apoptotic index. Secondary outcomes included biomarker differences at the studied times and some clinical variables such as length of hospital stay, and quality and safety issues related to the procedure.

RESULTS

Peritoneal IL6 after 1 hour of surgery was significantly higher in the standard than in the low-pressure group (4.26±1.34 vs. 3.24±1.21; P =0.001). On the contrary, levels of connective tissue growth factor and plasminogen activator inhibitor-I were higher in the low-pressure group (0.89±0.61 vs. 0.61±0.84; P =0.025, and 0.74±0.89 vs. 0.24±1.15; P =0.028, respectively). Regarding apoptotic index, similar levels were found in both groups and were 44.0±10.9 and 42.5±17.8 in low and standard pressure groups, respectively. None of the secondary outcomes showed differences between the 2 groups.

CONCLUSIONS

Peritoneal inflammation after laparoscopic cholecystectomy is higher when surgery is performed under standard pressure. Adhesion formation seems to be less in this group. The majority of patients undergoing surgery under low pressure were operated under optimal workspace conditions, regardless of the surgeon's expertise.

Probiotics in Postoperative Pain Management

Postoperative pain is the unpleasant sensory and emotional experience after surgery, its origin being both the inflammatory reaction induced by the surgical trauma on the abdominal wall and the splanchnic pain induced by the activation of nociceptors of the viscera, which are highly sensitive to distension, ischemia, and inflammation. Nowadays, it is well recognized that there is a close relationship between the gut microbiome and pain perception, and that microbiome is highly affected by both anesthesia and surgical manipulation. Thus, efforts to restore the disturbed microbiome via supplementation with beneficial bacteria, namely probiotics, seem to be effective. In this article, the knowledge gained mainly from experimental research on this topic is analyzed, the concluding message being that each probiotic strain works in its own way towards pain relief.

Multi-omic Profiling Reveals that Intra-abdominal-Hypertension-Induced Intestinal Damage Can Be Prevented by Microbiome and Metabolic Modulations with 5-Hydroxyindoleacetic Acid as a Diagnostic Marker

Emerging evidence shows that modulation of the microbiome can suppress intra-abdominal hypertension (IAH)-induced intestinal barrier damage through the regulation of amino acid (AA) biosynthesis. Here, we investigated the protective effects of orally gavaged Lactobacillus acidophilus L-92 (L92) and a mixture of AA in rats with induced IAH. The results showed that both L92 and AA pretreatments effectively mitigated IAH-induced intestinal damage. Interestingly, L92 but not AA prevented metagenomic changes induced by IAH. Bacteroides fragilis, Bacteroides eggerthii, Bacteroides ovatus, Faecalibacterium prausnitzii, Prevotella, and extensively altered functional pathways were associated with L92-mediated host protection. Metabolomic profiling revealed that tryptophan metabolism was involved in both L92- and AA-mediated gut protection. The tryptophan metabolite 5-hydroxyindoleacetic acid (5-HIAA) is a sensitive biomarker for IAH in rats and patients with either gut-derived sepsis (n = 41) or all-source sepsis (n = 293). In conclusion, we show that microbiome and metabolic modulations can effectively prevent IAH-induced intestinal damage and that 5-HIAA is a potential metabolic marker for IAH and sepsis.

IMPORTANCE Gut protection through modulation of the microbiome for critically ill patients has been gaining much attention recently. Intra-abdominal hypertension (IAH) is a prevailing clinical feature of acute gastrointestinal injuries in critically ill patients, characterized by nonspecific intestinal barrier damage. Prolonged IAH can induce or aggravate the development of sepsis and multiorgan dysfunctions. Therefore, the prevention of IAH-induced damage in rats through microbiome and metabolic interventions by commercially available L92 and AA treatments and the identification of 5-HIAA as an important marker for IAH/sepsis have important clinical implications for the treatment and early diagnosis of critically ill patients.

Bacterial Translocation in Gastrointestinal Cancers and Cancer Treatment

In recent years, there has been increasing evidence that gut microbiota is associated with the onset and exacerbation of various diseases, such as gastrointestinal cancer. For instance, it is well known that local inflammation of the intestinal tract in colorectal cancer that is caused by the increased number of Fusobacterium, due to changes in the intestinal bacterial flora, is involved in carcinogenesis. In contrast, gut bacteria or their products, pathogen-associated molecular patterns, not only cause intestinal inflammation but also invade the bloodstream through dysbiosis and gut barrier dysfunction, thereby leading to systemic inflammation, namely bacterial translocation. The involvement of bacterial translocation in the carcinogenesis of gastrointestinal cancers and their prognosis is increasingly being recognized. The Toll-like receptor signaling pathways plays an important role in the carcinogenesis of such cancers. In addition, bacterial translocation influences the treatment of cancers such as surgery and chemotherapy. In this review, we outline the concept of bacterial translocation, summarize the current knowledge on the relationship between gut bacteria and gastrointestinal cancer, and provide future perspectives of this field.

Gut-Barrier Disruption After Laparoscopic Versus Open Major Liver Resection in the Rat

BACKGROUND

Major liver resection may compromise gut-barrier function, increasing the risk of postoperative infectious complications. The aim of the present experimental study was to compare the effect of the laparoscopic versus the open technique for major liver resection on integrity as well as inflammatory and immune responses of the gut barrier.

METHODS

Wistar rats were subjected to open 70% hepatectomy (group H), laparoscopic 70% hepatectomy (group LH), sham operation (group S) or no intervention (group C). At various timepoints (1 hour-1 week) after operation, ileal tissue was excised for oxidative state assessment (TBARS levels), histopathologic examination, histomorphometric analysis, immunohistochemical assessment of the mitotic and apoptotic activity, and tissue expression of inflammatory (interleukin-6, tumor necrosis factor-α, nuclear factor-κB and vascular cell adhesion molecule-1) and immune response biomarkers (CD4⁺ and CD8⁺ T-lymphocytes) of the intestinal mucosa.

RESULTS

No changes were noted in oxidative state. The histopathologic profile was less deteriorated in group LH compared to group H. Intestinal mucosa atrophy was less intense in group LH compared to group H and was related to an equally compromised crypt cell mitotic activity. Tissue overexpression of interleukin-6, tumor necrosis factor-α, nuclear factor-κΒ, vascular cell adhesion molecule-1, CD4⁺, and CD8⁺ T-lymphocytes was less pronounced in group LH compared to group H.

CONCLUSION

The employment of the laparoscopic technique for major liver resection in the rat attenuated disruption of the gut barrier compared to the open procedure. This was related to less pronounced inflammatory and immune responses of the intestinal mucosa.

The intestinal fatty acid-binding protein as a marker for intestinal damage in gastroschisis

Background/Purpose

We analyzed the capacity of urinary Intestinal fatty acid-binding protein (I-FABP) to quantify the degree of mucosal injury in neonates with gastroschisis (GS) and to predict the speed of their clinical recovery after surgery.

Methods

In this prospective study, we collected urine during the first 48h after surgery from neonates operated between 2012 and 2015 for GS. Neonates with surgery that did not include gut mucosa served as controls for simple GS and neonates with surgery for intestinal atresia served as control for complex GS patients. The I-FABP levels were analyzed by ELISA.

Results

Urinary I-FABP after the surgery is significantly higher in GS newborns than in control group; I-FABP in complex GS is higher than in simple GS. I-FABP can predict subsequent operation for ileus in patients with complex GS. Both ways of abdominal wall closure (i.e. primary closure and stepwise reconstruction) led to similar levels of I-FABP. None of the static I-FABP values was useful for the outcome prediction. The steep decrease in I-FABP after the surgery is associated with faster recovery, but it cannot predict early start of minimal enteral feeding, full enteral feeding or length of hospitalization.

Conclusion

Urinary I-FABP reflects the mucosal damage in gastroschisis but it has only a limited predictive value for patients’ outcome.

Electro-acupuncture attenuates inflammatory responses and intraabdominal pressure in septic patients: A randomized controlled trial

BACKGROUND

A pathological increase in intraabdominal pressure (IAP) and inflammatory responses have negative effects on splanchnic, respiratory, cardiovascular, renal, and neurological function in septic patients with intestinal dysfunction. Electro-acupuncture (EA) has been evidenced to have a bidirectional neuron-endocrine-immune system regulating effect in patients with intestinal dysfunction. The purpose of current study was to evaluate the effects of EA at "Zusanli" (ST36) and "Shangjuxu" (ST37) on inflammatory responses and IAP in septic patients with intestinal dysfunction manifested syndrome of obstruction of the bowels Qi.

METHODS

Eighty-two septic patients with intestinal dysfunction manifested syndrome of obstruction of the bowels Qi were randomly assigned to control group (n = 41) and EA group (n = 41). Patients in control group were given conventional therapies including fluid resuscitation, antiinfection, vasoactive agents, mechanical ventilation (MV), supply of enteral nutrition, and glutamine as soon as possible. In addition to conventional therapies, patients in EA group underwent 20-minutes of EA at ST36-ST37 twice a day for 5 days. At baseline, posttreatment 1, 3, and 7 days, serum levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) and IAP levels, were measured, respectively. And days on MV, length of stay in intensive care unit (ICU) and 28 days mortality were recorded.

RESULTS

The serum levels of TNF-α and IL-1β and IAP levels at posttreatment 1, 3, and 7 days were lower significantly in the EA group compared with the control group (mean [SD]; 61.03 [20.39] vs 79.28 [20.69]; P < .005, mean [SD]; 35.34 [18.75] vs 66.53 [30.43]; P < .005 and mean [SD]; 20.32 [11.30] vs 32.99 [20.62]; P = .001, respectively, TNF-α. Mean [SD]; 14.11 [5.21] vs 16.72 [5.59]; P = .032, mean [SD]; 9.02 [3.62] vs 12.10 [4.13]; P = .001 and mean [SD]; 5.11 [1.79] vs 8.19 [2.99]; P < .005, respectively, IL-1β. Mean [SD]; 14.83 [5.58] vs 17.55 [3.37]; P = .009, mean [SD]; 11.20 [2.57] vs 14.85 [3.01]; P < .005 and mean [SD]; 8.62 [2.55] vs 11.25 [2.72]; P < .005, respectively, IAP). There were no significant differences in the duration of MV, length of stay in ICU, and 28d mortality between the groups.

CONCLUSION

EA at ST36-ST37 attenuated inflammatory responses through reduction in serum levels of TNF-α and IL-1β and IAP in septic patients with intestinal dysfunction manifested syndrome of obstruction of the bowels Qi.

The Influence of Carbon Dioxide Pneumoperitoneum on Systemic Inflammatory Response Syndrome and Bacterial Translocation in Patients With Bacterial Peritonitis Caused by Acute Appendicitis

OBJECTIVE

To explore the influence of carbon dioxide pneumoperitoneum (CDP) on system inflammatory response syndrome (SIRS) and bacterial translocation (BT) in patients with bacterial peritonitis (BP) caused by acute appendicitis (AA).

METHODS

Eighty-six consecutive subjects were randomly divided into the laparoscopy and laparotomy groups (n = 44 and n = 42, respectively). The levels of white blood cells (WBC), C-reactive protein (CRP), tumor necrosis factor α (TNF-α), and interleukin 6 (IL-6) of the 2 groups were tested preoperatively and at days 1, 2, and 4 after surgery. Blood and secretion culture was performed to verify whether septicemia or incision infection occurred, respectively. And the abdominal ultrasound or computed tomography scanning was used to diagnose peritoneal abscess for the suspected patients. The essential risk factors related to the aggravation of SIRS were analyzed through analysis of variance and binary logistic regression.

RESULTS

The postoperative blood levels of WBC, CRP, TNF-α, and IL-6 on day 4 in the laparoscopy group were significantly lower than those in the control group (all Ps < .05). The differences in incidence rates of septicemia and peritoneal abscess between the CDP and control groups were not statistically significant ( P > .05). Nevertheless, the incision infection rate in the laparoscopy group was apparently lower than that in the control group (4.55% vs 19.04%, P = .047). Analysis of variance and binary logistic regression showed that the non-pneumoperitoneum, pathological type of appendicitis, and multidrug resistant infections were the 3 major risk factors for SIRS (the P values were .001, .019, and .012, respectively).

CONCLUSION

It was found that CDP is safe for BP and could be a potential protective factor to mitigate BP effectively, indicating that the performance of laparoscopy operation under CDP is feasible to control SIRS; at the same time, CDP would not raise the incidence rate of BT.

Doxycycline protects human intestinal cells from hypoxia/reoxygenation injury: Implications from an in-vitro hypoxia model

Intestinal ischemia/reperfusion (I/R) injury is a grave clinical emergency and associated with high morbidity and mortality rates. Based on the complex underlying mechanisms, a multimodal pharmacological approach seems necessary to prevent intestinal I/R injury. The antibiotic drug doxycycline, which exhibits a wide range of pleiotropic therapeutic properties, might be a promising candidate for also reducing I/R injury in the intestine. To investigate possible protective effects of doxycycline on intestinal I/R injury, human intestinal CaCo-2 cells were exposed to doxycycline at clinically relevant concentrations. In order to mimic I/R injury, CaCo-2 were thereafter subjected to hypoxia/reoxygenation by using our recently described two-enzyme in-vitro hypoxia model. Investigations of cell morphology, cell damage, apoptosis and hydrogen peroxide formation were performed 24h after the hypoxic insult. Hypoxia/reoxygenation injury resulted in morphological signs of cell damage, elevated LDH concentrations in the respective culture media (P<0.001) and increased protein expression of proapoptotic caspase-3 (P<0.05) in the intestinal cultures. These events were associated with increased levels hydrogen peroxide (P<0.001). Preincubation of CaCo-2 cells with different concentrations of doxycycline (5µM, 10µM, 50µM) reduced the hypoxia induced signs of cell damage and LDH release (P<0.001 for all concentrations). The reduction of cellular damage was associated with a reduced expression of caspase-3 (5µM, P<0.01; 10µM, P<0.01; 50µM, P<0.05), while hydrogen peroxide levels remained unchanged. In summary, doxycycline protects human intestinal cells from hypoxia/reoxygenation injury in-vitro. Further animal and clinical studies are required to prove the protective potential of doxycycline on intestinal I/R injury under in-vivo conditions.

MICU1 may be a promising intervention target for gut-derived sepsis induced by intra-abdominal hypertension

Intra-abdominal hypertension (IAH) is a common and serious complication in critically ill patients, for which there is no targeted therapy. IAH-induced dysfunction of intestinal barriers is closely associated with oxidative imbalances, which are considered to provide a pathophysiological basis for subsequent gut-derived sepsis. However, the upstream mechanism that produces oxidative damage during IAH remains unknown. It is not clear whether ‘mitochondrial Ca²⁺ uptake 1’ (MICU1, the key protein regulating the oxidative process) is involved in preventing Ca²⁺_m (mitochondrial Ca²⁺) overload. Here, we detected changes in the expression of MICU1 during the development of increased intestinal permeability in rats with IAH, and we explored the related mechanism regulating epithelial-barrier functions by knocking-down micu1 in Caco-2 cells. Our results demonstrated that, to combat IAH-induced dysfunction of intestinal barriers, MICU1 undergoes a compensatory increase in expression, whereas ‘mitochondrial calcium uniporter’ (MCU) – a conserved Ca²⁺ transporter – becomes transcriptionally suppressed. Silencing the expression of MICU1 destroyed Caco-2 cell barrier integrity, promoted paracellular permeability, and impaired the expression of tight junction proteins (occludin, ZO-1, and claudin 1). Meanwhile, oxidative imbalances were induced; malondialdehyde (MDA), a product of oxidation, was increased and antioxidant products (GSH-Px, CAT, and SOD) were decreased. In MICU1-deficient Caco-2 cells, proliferation was inhibited and apoptosis was promoted. Collectively, our results indicate that MICU1-related oxidation/antioxidation disequilibrium is strongly involved in IAH-induced damage to intestinal barriers. MICU1-targeted treatment may hold promise for preventing the progression of IAH to gut-derived sepsis.

The Effect of Elevated Intra-Abdominal Pressure on TLR4 Signaling in Intestinal Mucosa and on Intestinal Bacterial Translocation in a Rat

BACKGROUND

Recent evidence suggests that elevated intra-abdominal pressure (IAP) may adversely affect the intestinal barrier function. Toll-like receptor 4 (TLR-4) is responsible for the recognition of bacterial endotoxin or lipopolysaccharide and for initiation of the Gram-negative septic shock syndrome. The objective of the current study was to determine the effects of elevated IAP on intestinal bacterial translocation (BT) and TLR-4 signaling in intestinal mucosa in a rat model.

METHODS

Male Sprague-Dawley rats were randomly assigned to one of two experimental groups: sham animals (Sham) and IAP animals who were subjected to a 15 mmHg pressure pneumoperitoneum for 30 minutes. Rats were sacrificed 24 hours later. BT to mesenteric lymph nodes, liver, portal vein blood, and peripheral blood was determined at sacrifice. TLR4-related gene and protein expression (TLR-4; myeloid differentiation factor 88 [Myd88] and TNF-α receptor-associated factor 6 [TRAF6]) expression were determined using real-time PCR, western blotting, and immunohistochemistry.

RESULTS

Thirty percent of sham rats developed BT in the mesenteric lymph nodes (level I) and 20% of control rats developed BT in the liver and portal vein (level II). abdominal compartment syndrome (ACS) rats demonstrated an 80% BT in the lymph nodes (Level I) and 40% BT in the liver and portal vein (Level II). Elevated BT was accompanied by a significant increase in TLR-4 immunostaining in jejunum (51%) and ileum (35.9%), and in a number of TRAF6-positive cells in jejunum (2.1%) and ileum (24.01%) compared to control animals. ACS rats demonstrated a significant increase in TLR4 and MYD88 protein levels compared to control animals.

CONCLUSIONS

Twenty-four hours after the induction of elevated IAP in a rat model, increased BT rates were associated with increased TLR4 signaling in intestinal mucosa.

Gut microbiome, surgical complications and probiotics

The trigger for infectious complications in patients following major abdominal operations is classically attributed to endogenous enteral bacterial translocation, due to the critical condition of the gut. Today, extensive gut microbiome analysis has enabled us to understand that almost all "evidence-based" surgical or medical intervention (antibiotics, bowel preparation, opioids, deprivation of nutrition), in addition to stress-released hormones, could affect the relative abundance and diversity of the enteral microbiome, allowing harmful bacteria to proliferate in the place of depressed beneficial species. Furthermore, these bacteria, after tight sensing of host stress and its consequent humoral alterations, can and do switch their virulence accordingly, towards invasion of the host. Probiotics are the exogenously given, beneficial clusters of live bacteria that, upon digestion, seem to succeed in partially restoring the distorted microbial diversity, thus reducing the infectious complications occurring in surgical and critically ill patients. This review presents the latest data on the interrelationship between the gut microbiome and the occurrence of complications after colon surgery, and the efficacy of probiotics as therapeutic instruments for changing the bacterial imbalance.

Effect of bowel resection on TLR signaling during intestinal adaptation in a rat model

BACKGROUND

Bacterial overgrowth is common complication of short bowel syndrome (SBS) and is a result of an impaired gut barrier function. Toll-like receptor 4 (TLR4) is crucial in maintaining intestinal epithelial homeostasis, participates in a vigorous signaling process and heightens inflammatory cytokine output. The objective of this study was to determine the effects of bowel resection on TLR4 signaling in intestinal mucosa in a rat model.

METHODS

Male Sprague-Dawley rats were randomly assigned to one of the two experimental groups of eight rats each: Sham rats underwent bowel transection and re-anastomosis and SBS rats underwent 75 % small bowel resection. Rats were killed on day 14. Bacterial translocation (BT) to mesenteric lymph nodes, liver, portal blood and peripheral blood was determined at the kill. The expression of TLR4, MyD88 and TRAF6 in the intestinal mucosa was determined using real-time PCR, Western blot and immunohistochemistry.

RESULTS

SBS rats demonstrated a 100 % BT to lymph nodes and to liver (Level I), 80 % translocation to portal blood (Level II) and 60 % translocation to peripheral blood (Level III) at day 7 as well as a 100 % BT to lymph nodes and liver, and 40 % translocation to peripheral blood at day 14. Microarray expression profiling demonstrated that most of the TLR signaling-related genes were up-regulated in resected rats compared to control animals. SBS rats showed a significant increase in TLR4 and TRAF6 mRNA in jejunum and ileum, TLR4 and MyD88 protein expression in jejunum and ileum, and a significant increase in the number of TLR4 and TRAF6 positive cells (immunohistochemistry) compared to sham animals.

CONCLUSIONS

In a rat model of SBS, elevated intestinal BT is associated with a stimulated TLR4 signaling.

The effects of arginase inhibitor on lung oxidative stress and inflammation caused by pneumoperitoneum in rats

Background

Pneumoperitoneum-induced oxidative stress and organ injury are known to be associated with nitric oxide (NO) inactivation. Because arginase competes with NO synthase (NOS) for a common substrate, L-arginine, arginase inhibition may increase NO bioavailability. Therefore, we evaluated the ability of the arginase inhibitor, 2 (S)-amino-6-boronohexanoic acid (ABH), to attenuate pneumoperitoneum-induced decrease of NO bioavailability and lung injury.

Methods

Thirty rats were randomly divided into the following groups: 1) the PP-ABH group received a subcutaneous injection of ABH (5 mg/kg) 1 h before induction of pneumoperitoneum (insufflation to intraperitoneal pressure of 15 mmHg for 60 min); 2) the PP group received saline by subcutaneous injection 1 h before induction of pneumoperitoneum; and 3) the control group received saline by subcutaneous injection before a sham procedure with no gas insufflation. After desufflation, blood was collected to determine levels of plasma nitrite, NOS, inflammatory cytokines, and malondialdehyde, a marker of oxidative stress. Lung tissue was obtained for histological evaluation.

Results

We found that plasma nitrite levels were lower in the PP group and higher in the PP-ABH group, compared with controls (P <0.01 and P <0.05, respectively). In the PP group, endothelial NOS activity was decreased and inducible NOS activity was increased compared with the PP-ABH and control groups. Malondialdehyde levels increased 3-fold in the PP group and 2-fold in the PP-ABH group compared with controls. Tumor necrosis factor-α, interleukin-6, and interleukin-1ß levels were elevated in the PP group compared to the control group, but the increase in cytokine production was attenuated or blocked in the PP-ABH group. Lung injury scores were 4.8-fold higher in the PP group and 2-fold higher in the PP-ABH group compared with controls (P <0.001 and P <0.01, respectively).

Discussion

Pneumoperitoneum decreases NO bioavailability and increases the inflammation cytokines, resulting in organ injuries. Inhibition of arginase activity could maintain NO bioavailability by attenuating pneumoperitoneum-induced changes in NOS activity. In addition, arginase inhibition attenuated the oxidative stress and inflammation and decreased the severity of lung injury caused by pneumoperitoneum.

Conclusions

By increasing NO bioavailability and suppressing oxidative stress and inflammation, pretreatment with an arginase inhibitor may protect against lung injury caused by pneumoperitoneum.

Does elevated intra-abdominal pressure during laparoscopic colorectal surgery cause acute gastrointestinal injury?

Introduction

The incidence of acute gastrointestinal injury (AGI) after colorectal surgery is low when laparoscopic techniques are used. While elevated intra-abdominal pressure (IAP) and intra-abdominal hypertension (IAH) are associated with AGI grade II, little is known about the relation between increased IAP during laparoscopy and subsequent AGI.

Aim

To assess the impact of increased IAP during laparoscopic colorectal surgery on the incidence of postoperative AGI.

Material and methods

Sixty-six patients (41 men and 25 women) with colorectal cancer undergoing elective laparoscopic colorectal surgery were randomized into 3 groups, according to different IAP levels during CO₂ pneumoperitoneum (10 mm Hg, 12 mm Hg and 15 mm Hg). We recorded the incidence of AGI after surgery by assessing the following parameters: time to first flatus/defecation, time to first bowel movement, time to tolerance of semi-liquid food and the occurrence of vomiting/diarrhea. Moreover, inflammatory mediators were measured before the induction of CO₂ pneumoperitoneum and on postoperative day 1.

Results

Acute gastrointestinal injury occurred in 15 (27.3%) patients. In all 3 study groups, the elevation of IAP during CO₂ pneumoperitoneum did not significantly increase the occurrence of symptoms of AGI, vomiting or diarrhea. Lower IAP levels did not significantly accelerate recovery of gastrointestinal function or shorten postoperative hospital stay. The changes in serum IL-6 after surgery did not correlate with the value of IAP.

Conclusions

The level of IAP elevation during laparoscopic colorectal surgery does not increase the occurrence of AGI after surgery.

Evaluation of total oxidant and antioxidant status in dogs under different CO2 pneumoperitoneum conditions

Background

The induction of the pneumoperitoneum increases intraabdominal pressure (IAP), causing splanchnic ischemia, whereas its deflation normalizes IAP and splanchnic blood flow. We investigated the oxidant-antioxidant status of dogs who underwent low pressure (7 mm Hg), standard pressure (12 mm Hg), and high pressure (15 mm Hg) pneumoperitoneum.

Results

Twenty-four beagle dogs (12 males and 12 females), 4–6 years old, weighing 8–11 kg were used. The animals were assigned to one of four groups (n = 6 dogs). Group 1 served as a control; these animals received only anaesthesia for 90 min. In groups 2, 3 and 4, intra-abdominal pressure was increased to 7, 12 and 15 mmHg, respectively, and maintained for 60 min. Total oxidant status (TOS) and total antioxidant status (TAS) were determined in venous blood samples. The percentage ratio of TOS to TAS provided an oxidative stress index (OSI).

No significant difference in TOS levels was found among the groups. A significant decrease in TAS levels and an increase in OSI levels were observed at 90 min and 24 h of pneumoperitoneum deflation within group 4. No differences were found among the groups.

Conclusions

A high pressure pneumoperitoneum induced significant changes in TAS and OSI. In addition, TOS and TAS levels are useful markers for evaluating changes in the oxidative status caused by a pneumoperitoneum during laparoscopy. Furthermore, a low-pressure pneumoperitoneum could attenuate oxidative stress induced by CO₂ insufflation in dogs.

Evidence for negative effects of elevated intra-abdominal pressure on pulmonary mechanics and oxidative stress

OBJECTIVE

To compare the effects of pneumoperitoneum on lung mechanics, end-tidal CO2 (ETCO2), arterial blood gases (ABG), and oxidative stress markers in blood and bronchoalveolar lavage fluid (BALF) during laparoscopic cholecystectomy (LC) by using lung-protective ventilation strategy.

MATERIALS AND METHODS

Forty-six patients undergoing LC and abdominal wall hernia (AWH) surgery were assigned into 2 groups. Measurements and blood samples were obtained before, during pneumoperitoneum, and at the end of surgery. BALF samples were obtained after anesthesia induction and at the end of surgery.

RESULTS

Peak inspiratory pressure, ETCO2, and pCO2 values at the 30th minute were significantly increased, while there was a significant decrease in dynamic lung compliance, pH, and pO2 values in LC group. In BALF samples, total oxidant status (TOS), arylesterase, paraoxonase, and malondialdehyde levels were significantly increased; the glutathione peroxidase levels were significantly decreased in LC group. The serum levels of TOS and paraoxonase were significantly higher at the end of surgery in LC group. In addition, arylesterase level in the 30th minute was increased compared to baseline. Serum paraoxonase level at the end of surgery was significantly increased when compared to AWH group.

CONCLUSIONS

Our study showed negative effects of pneumoperitoneum in both lung and systemic levels despite lung-protective ventilation strategy.

Laparoscopic versus open colorectal surgery for colon cancer: the effect of surgical trauma on the bacterial translocation. A prospective randomized study

BACKGROUND

Several studies suggest that surgical manipulation of the intestine and increased intra-abdominal pressure promotes bacterial translocation (BT). This prospective randomized study has investigated the effect of surgery on BT in patients undergoing elective colectomy for colon cancer by comparing the laparoscopic with the open approach.

METHODS

One hundred nineteen consecutive patients underwent colectomy for colon cancer: 59 cases underwent open resection and 60 cases underwent laparoscopic resection. For bacterial identification, tissue samples were taken from the liver, spleen, and mesenteric lymph nodes.

RESULTS

The incidence of BT increased in laparoscopic and open group after bowel mobilization (prior to ligation of the vascular pedicle), compared with the before mobilization (P < .05). There was not a statistically significant difference in BT value between the 2 groups.

CONCLUSION

BT increase was observed during the open and laparoscopic resection for colon cancer, without significant statistical difference between the 2 groups.

Ischemic reperfusion injury-induced oxidative stress and pro-inflammatory mediators in liver transplantation recipients

OBJECTIVE

Liver ischemic reperfusion injury is harmful to transplant recipients, and is associated with postoperative morbidity and mortality. Our study was designed to investigate the oxidative stress and pro-inflammatory mediators in liver transplant recipients.

METHODS

We prospectively analyzed 14 recipients who underwent liver transplantation by measuring their blood levels of malondialdehyde (MDA) and cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6, at nine time points perioperatively. We also evaluated the correlations between oxidative stress (MDA levels) and the characteristics of the recipient or the donated graft.

RESULTS

These parameters significantly increased from 1 minute before reperfusion, and the values peaked within 3 to 30 minutes after reperfusion. On the time point at 5 minutes after reperfusion, the MDA levels which were the highest in the recipients correlated with the values of preoperative direct/and total bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), model for end-stage liver disease (MELD) score, international normalized ratio (INR), and surgical blood loss.

CONCLUSION

The levels of MDA, TNF-α, IL-1β, and IL-6 greatly increased with the ischemic reperfusion insult. Recipients with higher values of preoperative direct/and total bilirubin, AST, ALT, MELD score, INR, and surgical blood loss tended to have higher levels of MDA and may suffer more injury from this insult.

Postinjury abdominal compartment syndrome: from recognition to prevention

Postinjury abdominal compartment syndrome (ACS) is an example of a deadly clinical occurrence that was eliminated by strategic research and focused preventions. In the 1990s, the syndrome emerged with the widespread use of damage control surgery and aggressive crystalloid-based resuscitation. Patients who previously exsanguinated on the operating table made it to intensive care units, but then developed highly lethal hyperacute respiratory, renal, and cardiac failure due to increased abdominal pressure. Among many factors, delayed haemorrhage control and preload driven excessive use of crystalloid resuscitation were identified as modifiable predictors. The surrogate effect of preventive strategies, including the challenge of the 40-year-old standard of large volume crystalloid resuscitation for traumatic shock, greatly reduced cases of ACS. The discoveries were rapidly translated to civilian and military trauma surgical practices and fundamentally changed the way trauma patients are resuscitated today with substantially improved outcomes.

Effect of acute, slightly increased intra-abdominal pressure on intestinal permeability and oxidative stress in a rat model

INTRODUCTION

Intra-abdominal hypertension (IAH) is known as a common, serious complication in critically ill patients. Bacterial translocation and permeability changes are considered the pathophysiological bases for IAH-induced enterogenic endotoxemia and subsequent multiorgan failure. Nevertheless, the effects of slightly elevated intra-abdominal pressures (IAPs) on the intestinal mucosa and the associated mechanisms remain unclear.

METHODS

To investigate the acute effects of different nitrogen pneumoperitoneum grades on colonic mucosa, male Sprague-Dawley rats were assigned to six groups with different IAPs (0 [control], 4, 8, 12, 16, and 20 mmHg, n = 6/group). During 90 min of exposure, we dynamically monitored the heart rate and noninvasive hemodynamic parameters. After gradual decompression, arterial blood gas analyses were conducted. Thereafter, structural injuries to the colonic mucosa were identified using light microscopy. Colon permeability was determined using the expression of tight junction proteins, combined with fluorescein isothiocyanate dextran (FD-4) absorption. The pro-oxidant-antioxidant balance was determined based on the levels of malondialdehyde (MDA) and antioxidant enzymes.

RESULTS

IAH significantly affected the histological scores of the colonic mucosa, tight junction protein expression, mucosal permeability, and pro-oxidant-antioxidant balance. Interestingly, elevations of IAP that were lower than the threshold for IAH also showed a similar, undesirable effect. In the 8 mmHg group, mild hyponatremia, hypocalcemia, and hypoxemia occurred, accompanied by reduced blood and abdominal perfusion pressures. Mild microscopic inflammatory infiltration and increased MDA levels were also detected. Moreover, an 8-mm Hg IAP markedly inhibited the expression of tight junction proteins, although no significant differences in FD-4 permeability were observed between the 0- and 8-mmHg groups.

CONCLUSIONS

Acute exposure to slightly elevated IAP may result in adverse effects on intestinal permeability and the pro-oxidant-antioxidant balance. Therefore, in patients with critical illnesses, IAP should be dynamically monitored and corrected, as soon as possible, to prevent intestinal mucosal injury and subsequent gut-derived sepsis.

Pre-eclampsia renamed and reframed: Intra-abdominal hypertension in pregnancy

This hypothesis proposes pre-eclampsia is caused by intra-abdominal hypertension in pregnancy. Sustained or increasing intra-abdominal pressure ⩾12mmHg causes impaired venous return to the heart, systemic vascular resistance, ischemia reperfusion injury, intestinal permeability, translocation of lipopolysaccharide endotoxin to the liver, cytotoxic immune response, systemic inflammatory response, pressure transmission to thoracic and intra-cranial compartments, and multi-organ dysfunction. This hypothesis is predicated on Pascal's law, evidence founded in the intra-abdominal hypertension literature, and the adapted equation ΔIAP-P=ΔIAVF/Cab, where ΔIAP-P=change in intra-abdominal pressure in pregnancy, ΔIAVF=change in intra-abdominal vector force (volume and force direction) and Cab=abdominal compliance. Factors causing increased intra-abdominal pressure in pregnancy include: progressive uterine expansion, obstetrical factors that increase intra-uterine volume excessively or acutely, maternal anthropometric measurements that affect intra-abdominal pressure thresholds, maternal postures that increase abdominal force direction, abdominal compliance that is decreased, diminished with advancing gestation, or has reached maximum expansion, habitation at high altitude, and rapid drops in barometric pressure. We postulate that the threshold for lipopolysaccharide translocation depends on the magnitude of intra-abdominal pressure, the intestinal microbiome complex, and the degree of intestinal permeability. We advance that delivery cures pre-eclampsia through the mechanism of abdominal decompression.

What is the best animal model for acs?

INTRODUCTION

Current treatment of the abdominal compartment syndrome (ACS) is based on consensus definitions but several questions regarding fluid regime or critical level of intra-abdominal hypertension (IAH)) remain unsolved. It is questionable whether these issues can be addressed in prospective randomized trials in the near future. This review aimed to summarize current animal models and to outline requirements for the best model.

METHODS

PubMed® data base was searched for articles describing animal models of ACS.

RESULTS

25 articles were found. ACS in animals has not been defined yet. Investigations varied considerably regarding the experimental design. Animals were rats, rabbits, dogs and pigs with a bodyweight from 200g to 70 kg. IAP increase varied from 20 to 50 mmHg. The time period of IAH ranged between 30 min and 24h. The time between the IAH insult and organ dysfunction varied between 15 min and 18h. Investigations demonstrated that IAH is able to induce loss of intravascular volume, organ hypoperfusion, ischemic organ damage and multiple organ failure within 4 to 6h.

CONCLUSION

In contrast to IAH or pneumoperitoneum for surgical exposure, ACS in an animal may be stated if an artificially increased IAP leads to circulatory, respiratory and renal insufficiency. A next step in animal research would be the development of a "pathological" model in which haemorrhage or systemic inflammation together with resuscitation lead to abdominal fluid accumulation and increased intra-abdominal pressure.

Elevation of intra-abdominal pressure by pneumoperitoneum decreases pancreatic perfusion in an in vivo porcine model

BACKGROUND

The goal of this study is to examine changes in pancreatic perfusion due to pneumoperitoneum using perfusion CT in vivo.

METHODS

Three pigs were studied. Under general anesthesia, pneumoperitoneum was induced to 16 mm Hg. Perfusion CT scans were acquired at a rate of 1 image per 2 seconds for 60 seconds. Scans were repeated 5 days later without pneumoperitoneum using the same protocol, in the same animals. The time density curve, color map, peak enhancement, time to peak, blood flow, blood volume, and permeability were evaluated.

RESULTS

In the presence of pneumoperitoneum, peak enhancement in radiodensity was decreased and time to peak was increased, and both blood flow and blood volume decreased. However, there was no consistent change in permeability observed.

CONCLUSION

This study demonstrates that pneumoperitoneum quantitatively results in decreased blood flow and blood volume to the pancreas in an in vivo animal model.

Effects of doxycycline on intestinal ischemia reperfusion injury induced by abdominal compartment syndrome in a rat model

BACKGROUND

Abdominal compartment syndrome (ACS) refers to organ dysfunction and ischemia resulting from intra-abdominal hypertension (IAH). Ischemia of the gut results in the triggering of a systemic inflammatory response by releasing cytokines which, in turn, causes capillary leakage leading to bowel edema, further increasing intra-abdominal pressure and resulting in a morbid cycle of ischemia and edema.

OBJECTIVE

The aim of this study was to determine the effects of doxycycline on intestinal ischemia reperfusion (I/R) injury in a rat model of ACS.

METHODS

Sprague-Dawley rats were divided into 5 equal groups. In groups 1 and 2, saline (1 cc IP) was administered during induction of ACS and intestinal samples were removed at 1 and 24 hours, respectively, after decompression. In groups 3 and 4, doxycycline (10 mg/kg IP) was injected during induction of ACS and, similarly, intestinal samples were removed at 1 and 24 hours after decompression. In the control group (group 5), intestinal samples were collected without induction of ACS. Malon-dialdehyde (MDA), interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, matrix metalloproteinase-2 (MMP-2), and tissue inhibitor of metalloproteinase-1 were studied and the apoptotic cells were enumerated histopathologically. Apoptosis and β-cell lymphoma 2 (βcl-2) expression were assessed immunohistochemically.

RESULTS

Thirty-five rats were evenly divided into 5 groups of 7 rats each. MDA, IL-1β, IL-6, TNF-α, and MMP-2 levels were significantly higher in group 1 one hour after the reperfusion period compared with the control group (P < 0.001, P < 0.001, P < 0.05, P < 0.001, and P < 0.01, respectively). The same parameters were significantly lower in group 3, in which doxycycline was administered, than in group 1 (P < 0.001, P < 0.05, P < 0.05, P < 0.001, and P < 0.01, respectively). However, there was no significant difference between groups 2 and 4 in the 24th hour (all, P > 0.05). The mean (SD) number of apoptotic cells and the expression of βcl-2 was highest in group 2 at 24 hours after the reperfusion period (92.5 [11.4] and 35.9 [5.0], respectively) and significantly greater than that in group 4 (P < 0.001 and P < 0.05, respectively).

CONCLUSION

Doxycycline was associated with protective effects against I/R injury through decreasing apoptosis via attenuating the response of proinflammatory cytokines and inhibiting the activity of MMP-2 in this rat model.

Effects of different pressure levels of CO2 pneumoperitoneum on liver regeneration after liver resection in a rat model

BACKGROUND

A recent study demonstrated that high pressure of carbon dioxide (CO2) pneumoperitoneum before liver resection impairs postoperative liver regeneration. This study was aimed to investigate effects of varying insufflation pressures of CO2 pneumoperitoneum on liver regeneration using a rat model.

METHODS

180 male Wistar rats were randomly divided into three groups: control group (without preoperative pneumoperitoneum), low-pressure group (with preoperative pneumoperitoneum at 5 mmHg), and high-pressure group (with preoperative pneumoperitoneum at 10 mmHg). After pneumoperitoneum, all rats were subjected to 70% partial hepatic resection and then euthanized at 0 min, 12 h, and on postoperative days (PODs) 1, 2, 4, and 7. Following outcome parameters were used: liver regeneration (liver regeneration rate, mitotic count, Ki-67 labeling index), hepatocellular damage (serum aminotransferases), oxidative stress [serum malondialdehyde (MDA)], interleukin-6 (IL-6), and hepatocyte growth factor (HGF) expression in the liver tissue.

RESULTS

No significant differences were observed for all parameters between control and low-pressure groups. The liver regeneration rate and mitotic count were significantly decreased in the high-pressure group than in control and low-pressure groups on PODs 2 and 4. Postoperative hepatocellular damage was significantly greater in the high-pressure group on PODs 1, 2, 4, and 7 compared with control and/or low-pressure groups. Serum MDA levels were significantly higher in the high-pressure group on PODs 1 and 2, and serum IL-6 levels were significantly higher in the high-pressure group at 12 h and on POD 1, compared with control and/or low-pressure groups. The HGF tissue expression was significantly lower in the high-pressure group at 12 h and on PODs 1 and 4, compared with that in control and/or low-pressure groups.

CONCLUSIONS

High-pressure pneumoperitoneum before 70% liver resection impairs postoperative liver regeneration, but low-pressure pneumoperitoneum has no adverse effects. This study suggests that following laparoscopic liver resection using appropriate pneumoperitoneum pressure, no impairment of liver regeneration occurs.

CO(2) pneumoperitoneum increases secretory IgA levels in the gut compared with laparotomy in an experimental animal model

BACKGROUND

Secretory immunoglobulin A (s-IgA) plays an important role in both gut and systemic immunity. This study aimed to investigate the production of s-IgA resulting from a CO2 pneumoperitoneum compared with a laparotomy.

METHODS

Using enzyme-linked immunosorbent assays, s-IgA in stool, malondialdehyde (MDA), and Toll-like receptor 4 (TLR4) in the ileal tissue were evaluated as markers for gut and systemic immune responses in an animal model. The rats were randomly divided into (i) anesthesia-only as the control group; (ii) laparotomy-only as the open group; and (iii) CO2 pneumoperitoneum-only as the pneumoperitoneum group. To evaluate the gut immune system in a time-dependent manner, each group was further divided into short- and long-time subgroups.

RESULTS

s-IgA levels did not increase in the open group but significantly increased in the pneumoperitoneum group compared with the control group (p < 0.05). In addition, s-IgA levels in the long-time subgroup significantly increased compared with the short-time subgroup of the pneumoperitoneum group (p < 0.05). TLR4 levels steeply and gradually increased in the open and pneumoperitoneum groups, respectively. MDA levels in the pneumoperitoneum group increased during the early phase and were significantly higher than those in the open group at 24 h (p < 0.05).

CONCLUSIONS

This study demonstrated that s-IgA levels in stool increased in the pneumoperitoneum group compared with the open group, suggesting that CO2 pneumoperitoneum may cause transitory damage to the intestinal mucosa.

The effect of dexmedetomidine on oxidative stress during pneumoperitoneum

Purpose. This study was intended to investigate the effect of dexmedetomidine on oxidative stress response in pneumoperitoneum established in rats. Methods. Animals were randomized into three groups, group S: with no pneumoperitoneum, group P: with pneumoperitoneum established, and group D: given 100 mcg intraperitoneal dexmedetomidine 30 min before establishment of pneumoperitoneum. Plasma total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) activity were measured 30 min after conclusion of pneumoperitoneum. Results. The mean TOS level was significantly higher in group P than in the other two groups, and the TOS level was significantly higher in group D than in group S (P < 0.05). Plasma TAS level was found to be lower in group P than in the other two groups, and the TAS level was lower in group D than in group S (P < 0.05). Consequently, the OSI was significantly higher in group P than in groups D and S (P < 0.05). Conclusions. Ischemia-reperfusion phenomenon that occurs during pneumoperitoneum causes oxidative stress and consumption of plasma antioxidants. Dexmedetomidine decreases oxidative stress caused by pneumoperitoneum and strengthens the antioxidant defense system.

Montelukast prevents ischaemia/reperfusion-induced ovarian damage in rats

OBJECTIVE

To investigate the efficacy of montelukast for prevention of ischaemia/reperfusion (I/R) injury in rat ovary.

STUDY DESIGN

Twenty-four female adult rats were included in the study. I/R injury was induced by CO2 pneumoperitoneum in a laparoscopic rat model. The rats were divided at random into three groups: the sham group was subjected to catheter insertion but was not subjected to pneumoperitoneum; the saline group was subjected to 60 min of pneumoperitoneum and 30 min of reperfusion, with 1 mg/kg physiological saline administered 10 min before pneumoperitoneum; and the montelukast group was subjected to 60 min of pneumoperitoneum and 30 min of reperfusion, with 20mg/kg montelukast administered 10 min before pneumoperitoneum. Damage to ovarian tissue was scored by histopathological evaluation. Caspase-3 expression was determined immunohistochemically. Ovarian tissue levels of malondialdehyde and glutathione, and plasma total antioxidant capacity were measured biochemically.

RESULTS

In comparison with the sham group, ovarian sections in the montelukast group had higher scores for follicular degeneration and oedema (p<0.001). Montelukast treatment prevented tissue damage in ovaries, and this result was significant. Caspase-3 expression was only observed in ovarian surface epithelium in the saline and montelukast groups. However, the mean caspase-3 expression score was higher in the saline group than the montelukast group (p<0.001). Tissue levels of malondialdehyde were higher in the montelukast group than the sham group, but plasma total antioxidant capacity and tissue levels of glutathione were significantly lower. Pretreatment with montelukast reduced lipid peroxidation (p<0.005) and improved antioxidant status in rats (p<0.001).

CONCLUSION

Montelukast is effective for the prevention of I/R-induced damage in rat ovary.

Intestinal permeability, systemic endotoxemia, and bacterial translocation after open or laparoscopic resection for colon cancer: a prospective randomized study

PURPOSE

In this prospective randomized study, we investigated the effect of surgery on intestinal permeability (IP), endotoxemia, and bacterial translocation (BT) in patients undergoing elective colectomy for colon cancer by comparing the laparoscopic with the open approach.

METHODS

Seventy-two consecutive patients underwent colectomy for colon cancer: 35 cases open resection and 37 cases laparoscopic resection. IP was measured preoperatively and at days 1 and 3 after surgery. Serial venous blood sample were taken at 0, 30, 60, 90, 120, and 180 min and at 12, 24, and 48 h after surgery for endotoxin measurement. Tissue sample were taken from the liver, spleen, and mesenteric lymph nodes and were weighed under sterile conditions.

RESULTS

IP was significantly increased in the open and closed group at day 1 compared with the preoperative level (p < 0.05), but no difference was found between laparoscopic and open surgery group. The concentration endotoxin systemic increased significantly in the both group during the course of surgery but returned to baseline levels at the second day 2. No difference was found between laparoscopic and open surgery. A significant correlation was observed between the maximum systemic endotoxin concentration and IP measured at D1 in the open group and in the laparoscopic group. The incidence of BT increased in laparoscopic and open group after bowel mobilization, compared with the before mobilization (p < 0.05). There was not a statistically significant difference in BT value between the two groups.

CONCLUSION

An increase in IP, systemic endotoxemia, and BT were observed during the open and laparoscopic resection for colon cancer, without significant statistically difference between the two groups.

Surveillance of intra-abdominal pressure and intestinal barrier function in a rat model of acute necrotizing pancreatitis and its potential early therapeutic window

OBJECTIVES

To monitor intra-abdominal pressure (IAP) and intestinal barrier function in a rat model of acute necrotizing pancreatitis (ANP) to elucidate a potential relevant therapeutic window.

METHODS

Sprague-Dawley rats were randomly divided into experimental or control groups. The ANP group (n = 40) was injected with 4.5% sodium taurocholate into the pancreatic duct to induce ANP. The controls received only abdominal opening surgery (sham-operated, SO; n = 40) or no treatment or surgery (baseline; 0 h, n = 20). The SO and ANP groups were then randomly subdivided into 3, 6, 12 and 24 h groups (n = 10 each). IAP was measured at each time point and the rats were sacrificed to measure the weight of accumulated ascites fluid and the amylase, endogenous creatinine (Cr), total bilirubin (TB), tumor necrosis factor- alpha (TNF-alpha), diamine oxidase (DAO), and D-lactate. Mortality and the development of pathological changes in the pancreas and intestines were also monitored.

RESULTS

IAP showed a continuous upward trend in the ANP group, with values 2 to 3 times higher than those in the SO group at the corresponding time points and the rising rate was peaking at 6 h. The levels of plasma amylase, TNF-alpha, Cr, TB, DAO, and D-lactate also gradually increased in the ANP group over time and were significantly higher than in the SO group at 3, 6, 12 and 24 h (all P<0.05). Moreover, the rising rate of TNF-alpha, DAO, and D-lactate also peaked at 6 h.

CONCLUSIONS

The ANP-induced changes in IAP, inflammatory factors and intestinal barrier that we observed in the rat model were especially obvious at 6 h post-induction, suggesting an early therapeutic window for the treatment of ANP in humans.

A new model for the study of secondary intra-abdominal hypertension in rats

BACKGROUND

To build a new and appropriate model of secondary intra-abdominal hypertension (IAH) in rats.

METHODS

A total of 32 female Sprague-Dawley rats were randomized into four groups. Group I: the rats were hemorrhaged to a mean arterial pressure (MAP) of 40 mm Hg for 1 h and portal hypertension was induced by partial ligation of the portal vein 1 h later; Group II: after inducing portal hypertension, hemorrhagic shock of MAP of 40 mm Hg was induced and maintained for 1 h; Group III: after inducing portal hypertension, hemorrhagic shock of MAP of 40 mm Hg was induced and maintained for 2 h; Group IV: after inducing portal hypertension, hemorrhagic shock of MAP of 40 mm Hg was induced and maintained for 2 h, and a specially designed abdominal restraint device was used. After these procedures, respectively, the collected blood was reinfused and lactated Ringer solution was continuously infused until the secondary IAH model was established.

RESULTS

No models were built in Groups I, II, and III. One rat died in Group IV after portal vein ligation, and all the remaining rats successfully developed IAH; the success rate was 87.5%. During the resuscitation period, the average time was 5.26 ± 0.59 h and the average total infusion volume was 665.5 ± 86.04 mL/kg.

CONCLUSION

A rat model of secondary IAH was successfully established by resuscitation after a combination of inducing portal hypertension, hemorrhaging to a MAP of 40 mm Hg for 2 h, and using an abdominal restraint device. All these criteria mimic key etiological factors for the development of secondary IAH.

Use of dexmedetomidine to prevent pulmonary injury after pneumoperitoneum in ventilated rats

PURPOSE

This study examined the effectiveness of dexmedetomidine in preventing lung injury resulting from pneumoperitoneum in a ventilated rat model.

METHODS

Animals (n=18) were allocated randomly into 3 groups: control group, no pneumoperitoneum; sham group, pneumoperitoneum with intra-abdominal pressure of 12 mm Hg for 60 minutes; and dexmedetomidine group, dexmedetomidine administration 30 minutes before pneumoperitoneum. The rats were rested for 30 minutes after abdominal deflation. Then, blood samples were obtained for plasma malondialdehyde and ischemia-modified albumin (IMA) analyses. Tissue samples were taken for histopathologic examination and malondialdehyde analysis.

RESULTS

Compared with the control group, the sham group had a significantly higher level of plasma IMA. Pretreatment with dexmedetomidine significantly reduced the IMA level. Histopathologically, tissues from sham rats exhibited moderate or severe tissue damage, compared with control tissues. Dexmedetomidine-treated rats showed significantly less tissue damage than sham rats.

CONCLUSIONS

Dexmedetomidine prophylaxis resulted in significantly less IMA production and significantly less neutrophil infiltration, thereby helping to protect the lungs from injury after pneumoperitoneum.

Peritonitis from perforated peptic ulcer and immune response

BACKGROUND

Elevated intra-abdominal pressure during the laparoscopy may promote bacteremia, endotoxemia, and systemic inflammatory response. In patients with generalized peritonitis from perforated peptic ulcer (PPU), we sought to compare acute phase response, immunologic status, and bacterial translocation from laparoscopic and open approach.

STUDY DESIGN

From July 2005 to September 2011, 115 consecutive patients underwent peptic ulcer repair for PPU: 58 cases laparoscopic peptic ulcer repair (LR) and 57 cases open peptic ulcer repair (OR). Bacteremia, endotoxemia, white blood cells population, human leukocyte antigen-DR (HLA-DR), neutrophil-elastase, interleukin-1 and 6 (IL-1 and IL-6), and C-reactive protein (CRP) were investigated.

RESULTS

Patients characteristics and grade of peritoneal contamination were similar in the two groups. One hour after intervention, bacteremia was significantly higher in the "open" group than in the laparoscopic group (p < .001). A significantly higher concentration of systemic endotoxin was detected intraoperatively in the "open" group of patients in comparison to the laparoscopic group (p < .0001). Laparotomy caused a significant increase in neutrophil concentration, neutrophil-elastase, IL-1 and IL-6, CRP, and decrease of HLA-DR. We recorded six cases (10.3%) of intra-abdominal abscess in the "open" group and one (1.7%) in laparoscopic group (p < .001).

CONCLUSIONS

OR, in case of peritonitis after PPU, increased the incidence of bacteremia, endotoxemia, and systemic inflammation compared with LR. Early enhanced postoperative systemic inflammation may cause lower transient immunologic defense after laparotomy (decrease of HLA-DR), leading to enhanced sepsis in these patients.

Minimally invasive surgery and oxidative stress response: what have we learned from animal studies?

Oxidative stress (OS) is an integral part of the surgical stress response. Minimally invasive surgery causes less trauma, and thus attenuated stress response is anticipated. However, the pneumoperitoneum or pneumoretroperitoneum is implicated in free radical production. This study reviewed available data on the impact of minimally invasive surgery on OS response of animal models in a systematic way. Databases were searched up to and including January 2010. Most of the studies investigated the effect of pneumoperitoneum on OS, 3 studies investigated the effect of pneumoretroperitoneum on OS. There was a great heterogeneity on experimental conditions including animal models, measured OS markers, methods, and time periods of measurement. Published animal data do not allow a reliable conclusion on the effect of minimally invasive surgery on OS because of the great heterogeneity of experimental conditions. Besides, most studies focus on the effect of pneumoperitoneum, without taking into consideration the effect of less surgical trauma.

Laparoscopy Decreases the Laparotomy Rate in Hemodynamically Stable Patients With Blunt Abdominal Trauma

Background. This study evaluated the use of laparoscopy in hemodynamically stable patients with blunt abdominal trauma. Methods. We retrospectively reviewed the medical records of hemodynamically stable blunt abdominal trauma patients. Patients admitted from July 1, 2003, to June 30, 2006 (prior to the adoption of laparoscopy for patients with blunt abdominal trauma) were categorized as group A. Patients admitted from July 1, 2007, to June 30, 2010, when laparoscopy was included in the algorithm for the management of blunt abdominal trauma, were categorized as group B. Results. There were 47 patients in group A and 57 patients in group B. There were no significant differences in demographic characteristics, injury severity score, and injuries requiring surgical intervention between the groups (all, P > .05). Patients in group B had a shorter hospital stay (11 days vs 21 days, P < .001) and shorter ICU stay (0 [0, 1] days vs 0 [0, 9] days, P = .029). In group A, 6 of 47 patients (12.8%) underwent a nontherapeutic laparotomy. In contrast, 9 of 57 patients (15.8%) in group B avoided a nontherapeutic laparotomy because no significant intra-abdominal findings warranting an intervention were disclosed by laparoscopy. The incidence of laparotomy for patients with significant injuries in group B was lower than in group A (4.2% vs 100.0%; P < .001). There was no difference in the complication rate between the groups. Conclusions. Laparoscopy is feasible and safe for the diagnosis and treatment of hemodynamically stable patients with blunt abdominal trauma and can reduce the laparotomy rate.

Metabolomic markers for intestinal ischemia in a mouse model

BACKGROUND

Diagnosis of intestinal ischemia remains a clinical challenge. The aim of the present study was to use a metabolomic protocol to identify upregulated and downregulated small molecules (M(r) < 500) in the serum of mice with intestinal ischemia. Such molecules could have clinical utility when evaluated as biomarkers in human studies.

METHODS

A mouse model for intestinal ischemia was established and validated using histology and serum tumor necrosis factor α concentrations. A second mouse model of peritoneal sepsis was used as a positive control. Serial serum samples were collected from these and from sham-operated animals. Sera were analyzed by gas chromatography-mass spectrometry for 40 small molecules as their trimethylsilyl and O-methyloxime derivatives. Peak areas were normalized against an internal standard and resultant peak area ratios subjected to multivariate data analysis using unsupervised principal components analysis and supervised orthogonal projection to latent structures-discriminant analysis. Upregulated and downregulated serum molecules were identified from their correlation to the orthogonal projection to latent structures-discriminant analysis model.

RESULTS

Three highly significantly upregulated (fold-change) serum molecules in intestinal ischemia were inorganic phosphate (2.4), urea (4.3), and threonic acid (2.9). Five highly significantly downregulated (fold-change) serum molecules were stearic acid (1.7), arabinose (2.7), xylose (1.6), glucose (1.4), and ribose (2.2). Lactic acid remained unchanged in intestinal ischemia.

CONCLUSIONS

Distinct molecular changes are reported here for the first time in intestinal ischemia. They reveal impairments of gut microbiota metabolism, intestinal absorption, and renal function, together with increased oxidative stress. In contrast to other reports, lactic acid was not significantly changed. These molecular signatures may now be evaluated in clinical studies.

Dynamic alteration of the colonic microbiota in intestinal ischemia-reperfusion injury

Background

Intestinal ischemia-reperfusion (I/R) plays an important role in critical illnesses. Gut flora participate in the pathogenesis of the injury. This study is aimed at unraveling colonic microbiota alteration pattern and identifying specific bacterial species that differ significantly as well as observing colonic epithelium change in the same injury model during the reperfusion time course.

Methodology/Principal Findings

Denaturing gradient gel electrophoresis (DGGE) was used to monitor the colonic microbiota of control rats and experimental rats that underwent 0.5 hour ischemia and 1, 3, 6, 12, 24, and 72 hours following reperfusion respectively. The microbiota similarity, bacterial diversity and species that characterized the dysbiosis were estimated based on the DGGE profiles using a combination of statistical approaches. The interested bacterial species in the gel were cut and sequenced and were subsequently quantified and confirmed with real-time PCR. Meanwhile, the epithelial barrier was checked by microscopy and D-lactate analysis. Colonic flora changed early and differed significantly at 6 hours after reperfusion and then started to recover. The shifts were characterized by the increase of Escherichia coli and Prevotella oralis, and Lactobacilli proliferation together with epithelia healing.

Conclusion/Significance

This study shows for the first time that intestinal ischemia-reperfusion results in colonic flora dysbiosis that follows epithelia damage, and identifies the bacterial species that contribute most.

Influence of two different levels of intra-abdominal hypertension on bacterial translocation in a porcine model

BACKGROUND

The purpose of the present study was to quantify bacterial translocation to mesenteric lymph nodes due to different levels of intra-abdominal hypertension (IAH; 15 vs. 30 mmHg) lasting for 24 h in a porcine model.

METHODS

We examined 18 anesthetized and intubated pigs (52.3 ± 4.7 kg) which were randomly allocated to three experimental groups (each n = 6) and studied over a period of 24 h. After preparation and establishing a steady state, the intra-abdominal pressure (IAP) was increased stepwise to 30 mmHg in six animals using a carbon dioxide (CO2) insufflator (IAP-30 group). In the second group, IAP was increased to 15 mmHg (IAP-15 group), while IAP remained unchanged in another six pigs (control group). Using a pulse contour cardiac output (PiCCO®) monitoring system, hemodynamic parameters as well as blood gases were recorded periodically. Moreover, peripheral and portal vein blood samples were taken for microbiological examinations. Lymph nodes from the ileocecal junction were sampled during an intra-vital laparotomy at the end of the observational period. After sacrificing the animals, bowel tissue samples and corresponding mesenteric lymph nodes (MLN) were extracted for histopathological and microbiological analyses.

RESULTS

Cardiac output decreased in all groups. In IAP-30 animals, volumetric preload indices significantly decreased, while those of IAP-15 pigs did not differ from those of controls. Under IAH, the mean arterial pressure (MAP) in the IAP-30 group declined, while MAP in the IAP-15 group was significantly elevated (controls unchanged). PO2 and PCO2 remained unchanged. The grade of ischemic damage of the intestines (histopathologically quantified using the Park score) increased significantly with different IAH levels. Accordingly, the amount of translocated bacteria in intestinal wall specimens as well as in MLN significantly increased with the level of IAH. Lymph node cultures confirmed the relation between bacterial translocation (BT) and IAP. The most often cultivated species were Escherichia coli, Staphylococcus, Clostridium, Pasteurella, and Streptococcus. Bacteremia was detected only occasionally in all three groups (not significantly different) showing gut-derived bacteria such as Proteus, Klebsiella, and E. coli spp.

CONCLUSION

In this porcine model, a higher level of ischemic damage and more BT were observed in animals subjected to an IAP of 30 mmHg when compared to animals subjected to an IAP of 15 mmHg or controls.