A. Schachtrupp

Mesh Implants in Hernia Repair Inflammatory Cell Response in a Rat Model

Background: In the reinforcement of the abdominal wall with mesh implants, various complications including hernia recurrence, abdominal pain, seroma formation and infection are discussed to depend on the biocompatibility of the alloplastic prosthesis. Particularly macrophages, T-cells and mast cells have been shown to play a major role in the inflammatory response to biomaterials. To approach biocompatibility of surgical meshes we therefore examined the infiltrate of these cells as well as the proliferation rate in response to different clinically applied materials. Materials and Methods: Three mesh materials (polypropylene: PP, Prolene®; polyethylene terephthalate: PET, Mersilene®, and polypropylene/polyglactin: PP + PG, Vypro®) were compared after inlay implantation in a standardized rodent animal model. A suture-closed laparotomy served as control. After 7 and 90 days of implantation, histochemical analysis of the inflammatory response to all biomaterials was performed: macrophages (ED3), T-cells (CD3), proliferating cells (PCNA) and mast cells (Giemsa) were investigated. Results: In all groups a persisting T-cell response was observed. Colonization of the interface with macrophages showed a pronounced reduction in the PP + PG-mesh group. Infiltration of mast cells at the tissue graft interface showed a time-dependent decrease in the PET- and PP + PG-mesh groups, whereas in contrast, index of mast cells increased in the PP-mesh group. At both time points, indices of proliferation were highest in the PP-mesh group. Conclusion: The present data confirm the development of a biomaterial-dependent chronic inflammatory response to surgical meshes with macrophages as the predominant cell type. Further research on the recruitment of inflammatory cells and in particular on the role of mast cells and their granular products should be encouraged.

Factors influencing the estimation of extravascular lung water by transpulmonary thermodilution in critically ill patients

Objective:To investigate factors that may influence the estimation of extravascular lung water (EVLW) with a single (cold) indicator compared with assessment using two indicators (thermo-dye dilution). Design:Post hoc analysis of an electronic hemodynamic database. Setting:Surgical intensive care unit of a university hospital. Patients:Forty-eight critically ill patients monitored by the thermo-dye dilution technique in the postoperative period. Interventions:None. Measurements and Main Results:The EVLW was simultaneously assessed by the thermo-dye dilution technique (EVLWref) and estimated by transpulmonary thermodilution (EVLWest). EVLWref index ranged between 1 and 40 mL/kg (mean 10 ± 7 mL/kg) and EVLWest between 2 and 39 mL/kg (mean 9 ± 6 mL/kg). EVLWref was closely correlated (r = .96) with EVLWest. The mean difference (bias) between EVLWref and EVLWest was −0.5 ± 1.9 mL/kg. The bias was not influenced by the weight, height, body surface area, body mass index, Pao2, intrathoracic blood volume, cardiac output, or dosage of vasoactive agents. In contrast, the bias was slightly but significantly influenced by EVLWref, Pao2/Fio2 ratio, tidal volume, and level of positive end-expiratory pressure. Conclusions:In our surgical intensive care unit population, the estimation of EVLW by transpulmonary thermodilution was influenced by the amount of EVLW, the Pao2/Fio2 ratio, the tidal volume, and the level of positive end-expiratory pressure. However, compared with the double indicator method, transpulmonary thermodilution estimation remained clinically acceptable even in patients with severe lung disease.

Intravascular volume depletion in a 24-hour porcine model of intra-abdominal hypertension

BACKGROUND The purpose of the study was to examine hemodynamic parameters and intravascular volume in a porcine model in the presence of intra-abdominal hypertension (IAH) lasting for 24 hours. METHODS Twelve pigs (52.5 +/- 4.9 kg) were studied over a period of 24 hours. In six animals, the intra-abdominal pressure was increased to 30 mm Hg via carbon dioxide-pneumoperitoneum. The others served as controls. Using the double-indicator dilution technique, intrathoracic blood volume (ITBV), total circulating blood volume, and cardiac output (CO) were measured. Standard parameters (e.g., central venous pressure [CVP]), were also recorded. RESULTS In the presence of IAH, ITBV and total circulating blood volume were significantly reduced to 55% and 67% of control values. CO decreased to 27% and CVP increased fourfold. CONCLUSION IAH leads to significant intravascular volume depletion that is not reflected by the CVP. Assessment of CO and ITBV in the presence of a critically increased intra-abdominal pressure is therefore recommended.

Fluid resuscitation preserves cardiac output but cannot prevent organ damage in a porcine model during 24 h of intraabdominal hypertension.

According to a previous study, a pathologically increased intraabdominal pressure (IAP) reduces cardiac output (CO) and results in medium- to high-grade organ damage in a porcine model of the abdominal compartment syndrome (ACS). The purpose of this study was to evaluate whether fluid resuscitation can preserve organ integrity together with CO. We examined 12 domestic pigs with a mean body weight of 48 kg. We used a CO2 pneumoperitoneum to increase the IAP to 30 mmHg in 6 animals, and the others served as control group. The investigation period was 24 h. In addition to a standard infusion regimen, Ringers solution was infused to maintain CO at the level of control animals. Hemodynamic parameters (ITBV, EVLW, MAP, CVP), urine output, inspiratory pressure, as well as serum parameters (e.g., ALT, lipase, AP, lactate, creatinine) were recorded. In the end histological examination of liver, bowel, kidney, and lung was performed. CO, ITBV, EVLW, and urine output did not change when compared with control. Fluid intake was increased (P < 0.01) when compared with control (10,570 ± 1,928 vs. 3,918 ± 1,042 mL). CVP, MAP, and inspiratory pressure were increased. Serum parameters did not change. Acidosis occurred in the study group. Liver, bowel, kidney, and lung displayed mean- to high-grade damage (P < 0.01). Although extensive fluid resuscitation preserved CO, diuresis, and serum parameters in this previously described model of the ACS, organ damage occurred. In the clinical regard, these results support decompressive treatment in the presence of pathologically high IAP despite “normalized” parameters.

Abdominelles Kompartmentsyndrom: Vermeidung und Behandlung

Zusammenfassung. Als abdominelles Kompartmentsyndrom ist eine intraabdominelle Druckerhöhung über 20 mmHg mit Anstieg des Beatmungsdrucks und Oligurie definiert. Bei dem primären abdominellen Kompartmentsyndrom bedingt eine Akuterkrankung (Peritonitis, Ileus, Abdominal- oder Beckentrauma) direkt die intraabdominelle Druckzunahme. Das sekundäre abdominelle Kompartmentsyndrom ist Folge eines forcierten Bauchdeckenverschlusses nach chirurgischen Interventionen (Ileus, Peritonitis, große Bauchwandhernien). Auswirkungen eines abdominellen Kompartmentsyndroms sind: Abnahme des Herzzeitvolumens, basale pulmonale Atelektasen, Oligo- bis Anurie, hepatische und intestinale Minderperfusion. Sinnvolles Monitoring ist eine standardisierte Messung des Blasendrucks. Normalwerte nicht operierter Patienten betragen 0–7 cm H2O, Normalwerte nach elektiven Laparotomien 5–12 cm H2O, der kritische Grenzbereich liegt zwischen 15–25 cm H2O, sicher pathologisch sind Werte > 25 cm H2O. Prophylaxe bzw. Therapie der Wahl bei manifestem abdominellem Kompartmentsyndrom ist die Anlage eines druckentlastenden Laparostomas mit resorbierbarem Netz. Zwischen 1988 und 1999 wurden bei 377 Patienten druckentlastende Laparostomata angelegt. Bei 16 % bestand ein primäres abdominelles Kompartmentsyndrom mit einem Blasendruck von 31 ± SD 4 cm H2O praeoperativ und von 17 ± 4 cm H2O nach Entlastung durch Laparostoma. Eine frühelektive Bauchwandrekonstruktion war bei 18 % der Patienten möglich. Schlußfolgerung: Das abdominelle Kompartmentsyndrom ist eine unterschätzte chirurgische Problemsituation, die multiple Organsysteme funktionell und strukturell schädigt. Der temporären Anlage eines druckentlastenden Laparostomas ist gegenüber einer erzwungenen Rekonstruktion der Bauchwandintegrität um jeden Preis der Vorzug zu geben. Ein pathophysiologisch orientiertes Verständnis für die funktionellen und systemischen Auswirkungen des Handelns ist Grundlage für moderne Chirurgie. Entsprechend kann ein erzwungener Bauchdeckenverschluß mit Stahldrähten und Gegendruckplatten keinen Platz im Konzept differenzierten chirurgischen Handelns mehr haben.Abstract. Abdominal compartment syndrome is defined by increased intraabdominal pressure above 20 mmHg with increased pulmonary peak pressure and oliguria. In primary abdominal compartment syndrome the increased intraabdominal pressure is caused directly by peritonitis, ileus or abdominal and pelvic trauma. Secondary compartment syndrome is a result of forced closure of the abdominal wall after abdominal surgery. The effects are decreased cardiac output, pulmonary atelectasis, oliguria to anuria and hepatic as well as intestinal reduction of perfusion. Effective monitoring is done by standardised measuring of urinary bladder pressure. Normal values are between 0 and 7 cm H2O, after elective laparotomies 5–12 cm H20. Above 25 cm H20 they are definitely pathological. For the prevention and therapy of manifested abdominal compartment syndrome the application of a laparostomy using a resorbable mesh is recommended. Between 1988 and 1999 we applied a laparostomy to lower the intraabdominal pressure in 377 patients. In 16 % of the cases it was indicated by primary abdominal compartment syndrome with a bladder pressure of 31 ± 4 cm H20 preoperatively, which could be lowered to 17 ± 4 cm H20 by laparostomy. An early reconstruction of the abdominal wall could be performed in 18 % of the cases. Conclusions: The abdominal compartment syndrome is an often underestimated problem in abdominal surgery involving multiple organ systems. The temporary laparostomy lowering intraabdominal pressure rather than a forced closure of the abdominal wall should be used in all circumstances.

Evaluation of a modified piezoresistive technique and a water-capsule technique for direct and continuous measurement of intra-abdominal pressure in a porcine model*

Objective:Intravesical pressure measurement is considered to be the gold standard for the assessment of intra-abdominal pressure. However, this method is indirect and depends on a physiologic bladder function. We evaluated a modified piezoresistive technique and a water-capsule technique for direct and continuous intra-abdominal pressure measurement. Design:Experimental study. Setting:Animal research laboratory. Subjects:Eleven male domestic pigs. Interventions:In anesthetized and mechanically ventilated animals, CO2 was insufflated to stepwise increase the intra-abdominal pressure to 30 mm Hg. Pressure was then held constant for 9 hrs followed by decompression. Piezoresistive measurement and water-capsule measurement probes were placed intra-abdominally. Measurements and Main Results:Readings of intravesical pressure measurement, piezoresistive measurement, and water-capsule measurement were taken hourly. Mean difference to insufflator readings, confidence intervals, and limits of agreement were calculated. Differences between applied pressure and intra-abdominal pressure readings were assessed using a two-factor analysis of variance. No significant differences between methods could be observed. During stepwise pressure increase, limits of agreements were −3.6 to 3.6 mm Hg. Confidence intervals were −3.4 to 3.5 (intravesical pressure measurement), −1.6 to 1.5 (piezoresistive measurement), and 0.5 to 2.9 mm Hg (water-capsule measurement). In the presence of constantly elevated intra-abdominal pressure, limits of agreement ranged from −8.2 to + 8.2 mm Hg. Confidence intervals were −0.4 to 6.2 (intravesical pressure measurement), −0.2 to 2.7 (piezoresistive measurement), and 1.1 to 5.1 mm Hg (water-capsule measurement). Conclusions:Both piezoresistive measurement and water-capsule measurement had smaller confidence intervals than intravesical pressure measurement, indicating higher precision, whereas water-capsule measurement had a significant offset. Piezoresistive measurement could be the most suitable device for continuous direct intra-abdominal pressure monitoring in specific patients.

Late bilateral diaphragmatic rupture: Challenging diagnostic and surgical repair

A 67-year-old man was referred to our department, after a vehicle accident, with multiple bone fractures and a left blunt diaphragmatic rupture. An emergency laparatomy was performed, and the left diaphragmatic defect directly sutured. Postoperatively, a delayed right diaphragmatic rupture occurred due to progressive inflammation and muscle devitalisation. The diagnosis was challenging because the right rupture became clinically evident later after extubation. Diaphragmatic reconstruction was performed through a right thoracotomy. A high index of suspicion should always be observed for missed or delayed bilateral diaphragmatic ruptures.

Abdominal compartment syndrome in childhood: diagnostics, therapy and survival rate

PurposeThe abdominal compartment syndrome (ACS) in childhood is a rare but dire disease if diagnosed delayed and treated improperly. The mortality amounts up to 60% (Beck et al. in Pediatr Crit Care Med 2:51–56, 2001). ACS is defined by a sustained rise of the intraabdominal pressure (IAP) together with newly developed organ dysfunction. The present study reports on 28 children with ACS to evaluate its potential role in the diagnosis, treatment and outcome of ACS.MethodsRetrospectively, medical reports and outcome of 28 children were evaluated who underwent surgical treatment for ACS. The diagnosis of ACS was established by clinical signs, intravesical pressure-measurements and concurrent organ dysfunction.ResultsPrimary ACS was found in 25 children (89.3%) predominantly resulting from polytrauma and peritonitis. Three children presented secondary ACS with sepsis (2 cases) and combustion (1 case) being the underlying causative diseases. Therapy of choice was the decompression of the abdominal cavity with implantation of an absorbable Vicryl® mesh. In 18 cases the abdominal cavity could be closed later, while in the other ten cases granulation of the mesh was allowed. The overall survival rate was 78.6% (22 of 28 children). The cause of death in the remaining six cases (21.4%) was sepsis with multiorgan failure.ConclusionOur results suggest that early establishment of the specific diagnosis of ACS followed by swift therapy with reduction of intraabdominal hypertension is essential in order to further reduce the high mortality rate associated with this condition.

Recognition and management of abdominal compartment syndrome among German pediatric intensivists: results of a national survey.

IntroductionSeveral decades ago, the beneficial effects of goal-directed therapy, which include decompressive laparotomy (DL) and open abdomen procedures in cases of intra-abdominal hypertension (IAH) in children, were proven in the context of closures of abdominal wall defects and large-for-size organ transplantations. Different neonatologic and pediatric disease patterns are also known to be capable of increasing intra-abdominal pressure (IAP). Nevertheless, a considerable knowledge transfer regarding such risk factors has hardly taken place. When left undetected and untreated, IAH threatens to evolve into abdominal compartment syndrome (ACS), which is accompanied by a mortality rate of up to 60% in children. Therefore, the present study looks at the recognition and knowledge of IAH/ACS among German pediatric intensivists.MethodsIn June 2010, a questionnaire was mailed to the heads of pediatric intensive care units of 205 German pediatric hospitals.ResultsThe response rate was 62%. At least one case of IAH was reported by 36% of respondents; at least one case of ACS, by 25%. Compared with adolescents, younger critically ill children appeared to develop IAH/ACS more often. Routine measurements of IAP were said to be performed by 20% of respondents. Bladder pressure was used most frequently (96%) to assess IAP. Some respondents (17%) only measured IAP in cases of organ dysfunction and failure. In 2009, the year preceding this study, 21% of respondents claimed to have performed a DL. Surgical decompression was indicated if signs of organ dysfunction were present. This was also done in cases of at least grade III IAH (IAP > 15 mmHg) without organ impairment.ConclusionsAlthough awareness among pediatricians appears to have been increasing over the last decade, definitions and guidelines regarding the diagnosis and management of IAH/ACS are not applied uniformly. This variability could express an ever present lack of awareness and solid prospective data.

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

BackgroundThe 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.MethodsWe 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.ResultsCardiac 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.ConclusionIn 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.