Abdominal insufflation for prevention of exsanguination

Development of a two-hit lethal liver injury model in swine

PURPOSE

Noncompressible truncal hemorrhage remains a leading cause of preventable death in the prehospital setting. Standardized and reproducible large animal models are essential to test new therapeutic strategies. However, existing injury models vary significantly in consistency and clinical accuracy. This study aims to develop a lethal porcine model to test hemostatic agents targeting noncompressible abdominal hemorrhages.

METHODS

We developed a two-hit injury model in Yorkshire swine, consisting of a grade IV liver injury combined with hemodilution. The hemodilution was induced by controlled exsanguination of 30% of the total blood volume and a 3:1 resuscitation with crystalloids. Subsequently, a grade IV liver injury was performed by sharp transection of both median lobes of the liver, resulting in major bleeding and severe hypotension. The abdominal incision was closed within 60 s from the injury. The endpoints included mortality, survival time, serum lab values, and blood loss within the abdomen.

RESULTS

This model was lethal in all animals (5/5), with a mean survival time of 24.4 ± 3.8 min. The standardized liver resection was uniform at 14.4 ± 2.1% of the total liver weight. Following the injury, the MAP dropped by 27 ± 8mmHg within the first 10 min. The use of a mixed injury model (i.e., open injury, closed hemorrhage) was instrumental in creating a standardized injury while allowing for a clinically significant hemorrhage.

CONCLUSION

This novel highly lethal, consistent, and clinically relevant translational model can be used to test and develop life-saving interventions for massive noncompressible abdominal hemorrhage.

Emerging Therapies for Prehospital Control of Hemorrhage

BACKGROUND

The aim of this review was to describe emerging therapies that could serve as a prehospital intervention to slow or stop noncompressible torso hemorrhage in the civilian and military settings. Hemorrhage accounts for 90% of potentially survivable military deaths and 30%-40% of trauma deaths. There is a great need to develop novel therapies to slow or stop noncompressible torso hemorrhage at the scene of the injury.

METHODS

A comprehensive literature search was performed using PubMed (1966 to present) for therapies not approved by the Food and Drug Administration for noncompressible torso hemorrhage in the prehospital setting. Therapies were divided into compressive versus intravascular injectable therapies. Ease of administration, skill required to use the therapy, safety profile, stability, shelf-life, mortality benefit, and efficacy were reviewed.

RESULTS

Multiple potential therapies for noncompressible torso hemorrhage are currently under active investigation. These include (1) tamponade therapies, such as gas insufflation and polyurethane foam injection; (2) freeze-dried blood products and alternatives such as lyophilized platelets; (3) nanoscale injectable therapies such as polyethylene glycol nanospheres, polyethylenimine nanoparticles, SynthoPlate, and tissue factor-targeted nanofibers; and (4) other injectable therapies such as polySTAT and adenosine, lidocaine, and magnesium. Although each of these therapies shows great promise at slowing or stopping hemorrhage in animal models of noncompressible hemorrhage, further research is needed to ensure safety and efficacy in humans.

CONCLUSIONS

Multiple novel therapies are currently under active investigation to slow or stop noncompressible torso hemorrhage in the prehospital setting and show promising results.

A systematic review of large animal models of combined traumatic brain injury and hemorrhagic shock

Traumatic brain injury (TBI) and severe blood loss (SBL) frequently co-occur in human trauma, resulting in high levels of mortality and morbidity. Importantly, each of the individual post-injury cascades is characterized by complex and potentially opposing pathophysiological responses, complicating optimal resuscitation and therapeutic approaches. Large animal models of poly-neurotrauma closely mimic human physiology, but a systematic literature review of published models has been lacking. The current review suggests a relative paucity of large animal poly-neurotrauma studies (N = 52), with meta-statistics revealing trends for animal species (exclusively swine), characteristics (use of single biological sex, use of juveniles) and TBI models. Although most studies have targeted blood loss volumes of 35-45%, the associated mortality rates are much lower relative to Class III/IV human trauma. This discrepancy may result from potentially mitigating experimental factors (e.g., mechanical ventilation prior to or during injury, pausing/resuming blood loss based on physiological parameters, administration of small volume fluid resuscitation) that are rarely associated with human trauma, highlighting the need for additional work in this area.

Feasibility of a Portable Abdominal Insufflation Device for Controlling Intraperitoneal Bleeding After Abdominal Blunt Trauma

Uncontrolled bleeding contributes to 30% to 40% of trauma-related deaths and is the leading cause of potentially preventable deaths. Currently, there is no effective method available to first responders for temporary control of noncompressible intraabdominal bleeding while patients are transported to the hospital. Our previous studies demonstrated that abdominal insufflation provides effective temporary bleeding control. The study aims to prove the feasibility (insufflation to a target pressure) and safety (cardiovascular and respiratory effects) of a novel portable abdominal insufflation device (PAID) designed to control the intraperitoneal bleeding caused by abdominal trauma. The PAID prototype is based on a patented design and manufactured via additive manufacturing. PAID contains a 16-g CO2cartridge and an electronic pressure transducer. PAID was tested on a bench top and a swine animal model. For the animal model study, the intraperitoneal pressure as well as cardiorespiratory parameters (hearth rate, SpO2[peripheral capillary oxygen saturation], and blood pressure) were continuously monitored during the insufflation procedure. The prototype functioned according to specifications on both bench top and animal models. CO2insufflation of the peritoneal cavity was delivered up the target 20 mm Hg and maintained for 30 minutes from 1 or 2 cartridges in the swine model. No intraoperative incidents were registered, and all the recorded physiological parameters were within normal limits. The PAID prototype is a feasible, easy to use device that provides quick, controlled, and safe insufflation of the peritoneal cavity. Future studies will focus on testing the next-generation, semiautomatic PAID prototype in a severe intraabdominal injury model.

A novel model of highly lethal uncontrolled torso hemorrhage in swine

INTRODUCTION

A reproducible, lethal noncompressible torso hemorrhage model is important to civilian and military trauma research. Current large animal models balancing clinical applicability with standardization and internal validity. As such, large animal models of trauma vary widely in the surgical literature, limiting comparisons. Our aim was to create and validate a porcine model of uncontrolled hemorrhage that maximizes reproducibility and standardization.

METHODS

Seven Yorkshire-cross swine were anesthetized, instrumented, and splenectomized. A simple liver tourniquet was applied before injury to prevent unregulated hemorrhage while creating a traumatic amputation of 30% of the liver. Release of the tourniquet and rapid abdominal closure following injury provided a standardized reference point for the onset and duration of uncontrolled hemorrhage. At the moment of death, the liver tourniquet was quickly reapplied to provide accurate quantification of intra-abdominal blood loss. Weight and volume of the resected and residual liver segments were measured. Hemodynamic parameters were recorded continuously throughout each experiment.

RESULTS

This liver injury was rapidly and universally lethal (11.2 ± 4.9 min). The volume of hemorrhage (35.8% ± 6% of total blood volume) and severity of uncontrolled hemorrhage (100% of animals deteriorated to a sustained mean arterial pressure <35 mmHg for 5 min) were consistent across all animals. Use of the tourniquet effectively halted preprocedure and postprocedure blood loss allowing for accurate quantification of amount of hemorrhage over a defined period. In addition, the tourniquet facilitated the creation of a consistent liver resection weight (0.0043 ± 0.0003 liver resection weight: body weight) and as a percentage of total liver resection weight (27% ± 2.2%).

CONCLUSIONS

This novel tourniquet-assisted noncompressible torso hemorrhage model creates a standardized, reproducible, highly lethal, and clinically applicable injury in swine. Use of the tourniquet allowed for consistent liver injury and precise control over hemorrhage. Recorded blood loss was similar across all animals. Improving reproducibility and standardization has the potential to offer improvements in large animal translational models of hemorrhage.

LEVEL OF EVIDENCE

Level I.

Prehospital control of life-threatening truncal and junctional haemorrhage is the ultimate challenge in optimizing trauma care; a review of treatment options and their applicability in the civilian trauma setting

Introduction

Exsanguination following trauma is potentially preventable. Extremity tourniquets have been successfully implemented in military and civilian prehospital care. Prehospital control of bleeding from the torso and junctional area’s remains challenging but offers a great potential to improve survival rates. This review aims to provide an overview of potential treatment options in both clinical as preclinical state of research on truncal and junctional bleeding. Since many options have been developed for application in the military primarily, translation to the civilian situation is discussed.

Methods

Medline (via Pubmed) and Embase were searched to identify known and potential prehospital treatment options. Search terms were|: haemorrhage/hemorrhage, exsanguination, junctional, truncal, intra-abdominal, intrathoracic, intervention, haemostasis/hemostasis, prehospital, en route, junctional tourniquet, REBOA, resuscitative thoracotomy, emergency thoracotomy, pelvic binder, pelvic sheet, circumferential. Treatment options were listed per anatomical site: axilla, groin, thorax, abdomen and pelvis Also, the available evidence was graded in (pre) clinical stadia of research.

Results

Identified treatment options were wound clamps, injectable haemostatic sponges, pelvic circumferential stabilizers, resuscitative thoracotomy, resuscitative endovascular balloon occlusion of the aorta (REBOA), intra-abdominal gas insufflation, intra-abdominal self-expanding foam, junctional and truncal tourniquets. A total of 70 papers on these aforementioned options was retrieved. No clinical reports on injectable haemostatic sponges, intra-abdominal insufflation or self-expanding foam injections and one type of junctional tourniquets were available.

Conclusion

Options to stop truncal and junctional traumatic haemorrhage in the prehospital arena are evolving and may offer a potentially great survival advantage. Because of differences in injury pattern, time to definitive care, different prehospital scenario’s and level of proficiency of care providers; successful translation of various military applications to the civilian situation has to be awaited. Overall, the level of evidence on the retrieved adjuncts is extremely low.

Traumatic intra-abdominal hemorrhage control: has current technology tipped the balance toward a role for prehospital intervention?

BACKGROUND

The identification and control of traumatic hemorrhage from the torso remains a major challenge and carries a significant mortality despite the reduction of transfer times. This review examines the current technologies that are available for abdominal hemorrhage control within the prehospital setting and evaluates their effectiveness.

METHODS

A systematic search of online databases was undertaken. Where appropriate, evidence was highlighted using the Oxford levels of clinical evidence. The primary outcome assessed was mortality, and secondary outcomes included blood loss and complications associated with each technique.

RESULTS

Of 89 studies, 34 met the inclusion criteria, of which 29 were preclinical in vivo trials and 5 were clinical. Techniques were subdivided into mechanical compression, endovascular control, and energy-based hemostatic devices. Gas insufflation and manual pressure techniques had no associated mortalities. There was one mortality with high intensity focused ultrasound. The intra-abdominal infiltration of foam treatment had 64% and the resuscitative endovascular balloon occlusion of the aorta had 74% mortality risk reduction. In the majority of cases, morbidity and blood loss associated with each interventional procedure were less than their respective controls.

CONCLUSION

Mortality from traumatic intra-abdominal hemorrhage could be reduced through early intervention at the scene by emerging technology. Manual pressure or the resuscitative endovascular balloon occlusion of the aorta techniques have demonstrated clinical effectiveness for the control of major vessel bleeding, although complications need to be carefully considered before advocating clinical use. At present, fast transfer to the trauma center remains paramount.

LEVEL OF EVIDENCE

Systematic review, level IV.

Intravenous hemostats: challenges in translation to patients

Excessive bleeding and the resulting complications are a leading killer of young people globally. There are many successful methods to halt bleeding in the extremities, including compression, tourniquets, and dressings. However, current treatments for internal hemorrhage (including from head or truncal injuries), termed non-compressible bleeding, are inadequate. For these non-compressible injuries, blood transfusions are the current treatment standard. However, they must be refrigerated, may potentially transfer disease, and are of limited supply. In addition, time is of the essence for halting hemorrhage, since more than a third of civilian deaths due to hemorrhage from trauma occur before the patient even reaches the hospital. As a result, particles that can cross-link activated platelets through the glycoprotein IIb/IIIa receptor expressed on activated platelets are being investigated as an alternative treatment for non-compressible bleeding. Ideally, these particles would interact specifically with platelets to stabilize the platelet plug. Initial designs used biologically derived microparticles with red blood cell fragment or albumin cores decorated with RGD or fibrinogen, which bind to GPIIb/IIIa. More recently there has been research into the use of fully synthetic nanoparticles with liposomal or polymer cores that crosslink platelets through a targeting peptide bound to the surface. Some of the challenges for the development of these particles include appropriate sizing to prevent blocking the capillaries of the lungs, immune system evasion to prevent strong reactions and increase circulation time, and storage and resuspension so that first responders can easily use the particles. In addition, the effectiveness of the variety of animal bleeding models in predicting outcomes must be examined before test results can be fully understood. Progress has been made in the development of particles to combat hemorrhage, but issues of immune sensitivity and storage must be resolved before these types of particles can be translated for human use.

Development of a lethal, closed-abdomen grade V hepato-portal injury model in non-coagulopathic swine

BACKGROUND

Hemorrhage within an intact abdominal cavity remains a leading cause of preventable death on the battlefield. Despite this need, there is no existing closed-cavity animal model to assess new hemostatic agents for the preoperative control of intra-abdominal hemorrhage.

METHODS

We developed a novel, lethal liver injury model in non-coagulopathic swine by strategic placement of two wire loops in the medial liver lobes including the hepatic and portal veins. Distraction resulted in grade V liver laceration with hepato-portal injury, massive bleeding, and severe hypotension. Crystalloid resuscitation was started once mean arterial pressure (MAP) fell below 65 mm Hg. Monitoring continued for up to 180 min.

RESULTS

We demonstrated 90% lethality (9/10) in swine receiving injury and fluid resuscitation, with a mean survival time of 43 min. Previous efforts in our laboratory to develop a consistently lethal swine model of abdominal solid organs, including preemptive anticoagulation, a two-hit injury with controlled hemorrhage prior to liver trauma, and the injury described above without resuscitation, consistently failed to result in lethal injury.

CONCLUSION

This model can be used to screen other interventions for pre hospital control of noncompressible.

Blood loss during laparoscopic radical prostatectomy - is it significant or not?

Introduction

The traditional assessment of blood loss during laparoscopic radical prostatectomy (LRP) is based on the blood volume collected intraoperatively in the suction device bottles. While this method is not perfect, analysis of changes in blood cell count (BCC) resulting from LRP is advisable.

Material and methods

71 men were submitted to LRP due to prostate cancer in our institution over an 18-month time period. From this group, we isolated 60 men with clinically minimal intraoperative blood loss (<200 ml) and included them into the study. Mean age of the cohort was 62.8 years. We performed standard BCC on the day before and 6 hours after the surgery. At the same time points, we measured creatinine serum concentration and calculated eGFR to avoid the data misinterpretation resulting from impaired renal function in the postoperative period.

Results

Statistically and clinically significant differences regarding all BCC parameters measured pre- and postoperatively were observed. The number of red blood cells, hemoglobin concentration, and hematocrit diminished by 17.5% (4.68T/l vs. 3.86T/l, p <0.02), 17.0% (8.93 mmol/l vs. 7.41 mmol/l, p < 0.02), and 17.9% (0.429 vs. 0.352, p <0.02), respectively. Simultaneously, renal function was stable with no significant change in eGFR (82.9 ml/min/1.73 m^2 vs. 79.09 ml/min/1.73 m^2, p = 0.28).

Conclusions

Standard LRP brings on a significant blood loss. While clinically insignificant, this blood loss seems to be as high as approx. 600 ml based on laboratory findings. BCC seems to be a more accurate method of intraoperative blood loss estimation compared to measurement of blood volume collected intraoperatively in the suction device bottles.

Hyperpressure intraperitoneal fluid administration for control of bleeding after liver injury

BACKGROUND

Acute hemorrhage is the principal cause of death in trauma patients, with most fatalities occurring during the pre-hospital phase. Recently, intra-abdominal insufflation by carbon dioxide has been shown to drastically reduce bleeding in vascular and splanchnic hemorrhagic animal models simulating the pre-hospital phase. Here, we propose that using dialysate fluid for increasing intra-abdominal pressure is at least as effective as gas with some potential advantages.

MATERIALS AND METHODS

A novel method of inducing liver trauma was used in 24 White New Zealand rabbits randomized into three groups: intra-abdominal carbon dioxide insufflation (GAS) with 15 cm H(2)O pressure; intra-abdominal infusion of type III dialysate solution (DIAL) with the same pressure; no change in intra-abdominal pressure (CTRL). All groups received intravenous resuscitation when their mean arterial pressure was below 30 mmHg. Physiologic parameters were recorded during 20 min of bleeding.

RESULTS

Red blood cell (RBC) volume loss in the DIAL and GAS was 45% and 48% lower than that in the CTRL, respectively (P < 0.0005). Similar trends were observed for losses in RBC count and hemoglobin (Hb). Final mean arterial pressure, arterial RBC, Hb, and hematocrit were higher in the DIAL and GAS than in the CTRL; glucose concentration in the DIAL group was significantly higher than that in the GAS and CTRL groups. No intravenous fluid therapy was needed in the DIAL group.

CONCLUSIONS

Hyperpressure intraperitoneal dialysate administration successfully reduced bleeding after severe liver injury in rabbits. This method can potentially be used as an adjunct to increase patient survival during pre-hospital cares.

Abdominal Insufflation Decreases Blood Loss without Worsening the Inflammatory Response: Implications for Prehospital Control of Internal Bleeding

Abdominal insufflation (AI) by carbon dioxide has been shown to decrease the rate of bleeding in different swine models of abdominal organ injuries. With development of appropriate tools, AI could be used to control bleeding temporarily in the prehospital setting. Concerns have been raised about the inflammatory response to AI, which could damage organs at a later stage despite initial hemostasis. We hypothesized that AI controls bleeding without inducing an unfavorable inflammatory response. An experimental splenic injury was caused in 28 Yorkshire pigs, which were randomized to: 1) standard resuscitation (n = 14) with crystalloids to a mean arterial pressure of 60 mm Hg, or 2) standard resuscitation and AI (n = 14) to an abdominal pressure of 20 cmH2O. The experiment lasted for 30 minutes, and intra-abdominal blood loss was measured. Blood serum interleukin 1β (IL-1β), transforming growth factor β1, and lung tissue heat shock protein 70 gene expression were measured at 0, 15, and 30 minutes, as markers of the inflammatory response. All animals survived to the end of the experiment. Total blood loss was significantly less in the AI group compared with the other standard resuscitation animals (733 ± 76 vs 1094 ± 153 mL, P = 0.049). The pH at the end of the experiment was significantly lower in the AI group (7.28 ± 0.02 vs 7.44 ± 0.05, P < 0.01) but there was no difference in lactate levels (1.5 ± 0.4 vs 1.7 ± 0.3, P = 0.7). Similarly, there was no difference in IL-1β, transforming growth factor β1, or lung tissue heat shock protein 70 gene expression between the two groups at any time point, although there was a trend towards lower IL-1β levels in the AI group. Our conclusion is that AI reduces blood loss from splenic injury without a measurable effect on the early inflammatory response in a clinically relevant animal model.

High-Pressure Fibrin Sealant Foam: An Effective Hemostatic Agent for Treating Severe Parenchymal Hemorrhage

BACKGROUND

The majority of early trauma deaths are related to uncontrolled, noncompressible, parenchymal hemorrhage from truncal injuries. The purpose of this study was to formulate a fibrin sealant foam (FSF) able to control severe parenchymal bleeding without compression or vascular control.

MATERIALS AND METHODS

FSF with high fibrinogen concentration (20 mg/mL) and low thrombin activity (5 U/mL) was prepared and pressurized by addition of liquid gas propellant. The efficacy of this foam was tested against a severe parenchymal hemorrhage, created by partial resection of liver lobes in anticoagulated rabbits (n = 7) and compared to untreated injury (n = 8) and placebo treatment (n = 7). The hemostatic efficacy of pressurized FSF (n = 8) was also compared to a commercially available liquid fibrin sealant (n = 8) and a developing dry powdered fibrin sealant product (n = 8) in the same model.

RESULTS

The liver injury resulted in 122 +/- 11.5 mL blood loss and death of 75% of untreated rabbits (3.2-3.4 kg) within 1 h. Treatment with placebo foam had no effect on blood loss or mortality rate. Pressurized FSF significantly reduced bleeding, resulting in 56% (P < 0.05) and 66% (P < 0.01) reduction in blood loss as compared to untreated or placebo-treated animals, respectively, and 100% survival (P = 0.008). When pressurized FSF was compared with liquid and powdered forms of fibrin sealant, only foam significantly reduced blood loss (49%, P < 0.05) and mortality rate (54%, P < 0.05) of rabbits as compared to untreated control animals (n = 9).

CONCLUSION

Biological nature, rapid preparation, coverage of large wound areas, and effective hemostatic properties make pressurized FSF an ideal candidate for treating nonoperable parenchymal injuries in damage control procedures.

Early laparoscopic management of acute postoperative hemorrhage after initial laparoscopic surgery

BACKGROUND AND PURPOSE

The use of laparoscopic surgery has been well established for the management of abdominal emergencies. However, the value of this technique for postoperative hemorrhage in urology has not been characterized. We present our favorable experience with laparoscopic exploration after urologic surgery and suggest guidelines for laparoscopic management of post-laparoscopy bleeding.

PATIENTS AND METHODS

Three patients who developed hemorrhage shortly after laparoscopic urologic surgery and were managed by laparoscopic exploration were identified from a series of 910 laparoscopic urologic procedures performed at our institution from October 2002 to June 2006.

RESULTS

Three patients, who were hemodynamically stable (two after robot-assisted laparoscopic prostatectomy, one after laparoscopic radical nephrectomy), required prompt surgical exploration for postoperative hemorrhage not stabilized by blood transfusion (mean 2.7 units) at a mean of 19.4 hours after initial surgery. Clots were evacuated with a 10-mm suction-irrigator. Two patients were found to have abdominal-wall arterial bleeding and were managed with suture ligation. The third patient demonstrated diffuse bleeding from the prostatic bed, which was controlled with Surgicel and FloSeal. Bleeding was efficiently controlled in all patients, and none required post-exploration transfusion. The mean post-exploration hospital stay was 2.3 days.

CONCLUSION

Significant hemorrhage after urologic laparoscopy is a rare event. We found laparoscopic exploration to be an excellent way to diagnose and correct such hemorrhage in certain patients. Early diagnosis with clinical and hematologic studies, a lowered threshold for surgical exploration, and specific operative equipment may decrease patient morbidity and the need for open surgical exploration.

Abdominal insufflation for control of bleeding after severe splenic injury

BACKGROUND

To date, there is no rapid method to control intracavitary bleeding without an operation. Over 70% of trauma deaths from uncontrollable internal bleeding occur early after injury before an operation is feasible. Abdominal insufflation (AI) by carbon dioxide has been shown to reduce the rate of bleeding after intra-abdominal injury in pigs. The concept was proven in highly lethal models of severe vascular and liver injuries. Similar injuries in humans would result in immediate exsanguination and low likelihood for any intervention. We hypothesized that AI would similarly reduce bleeding in a model of moderate but persistent bleeding from a splenic injury. This model represents a clinically relevant scenario of continuous bleeding, which does not kill the patient immediately but may ultimately result in death if not managed early.

METHODS

A new model of splenic injury was applied on 19 pigs, randomized to standard resuscitation (SR, N = 10) or standard resuscitation with AI to 20 cm H2O (SRAI, N = 9). For 30 minutes, the pigs were bled and the hemodynamics recorded. At 30 minutes, the abdomen was opened and free blood was collected and measured. Outcomes were blood loss, mean arterial pressure, hemoglobin, lactate levels, and arterial blood gases at the end of the experiment.

RESULTS

All pigs survived to the end of the experiment. Blood loss was lower (1,114 +/- 486 mL vs. 666 +/- 323 mL, p = 0.03) and final mean arterial pressure higher (64 +/- 12 mm Hg vs. 54 +/- 8 mm Hg, p = 0.04) in SRAI when compared with those in SR animals. Heart rate, arterial blood gases, oxygen saturation, hemoglobin, and lactate levels were similar in the two groups, except there was a more acidotic pH among SRAI animals (7.27 +/- 0.06 vs. 7.47 +/- 0.21, p = 0.02).

CONCLUSIONS

AI is a novel method to control intra-abdominal bleeding temporarily. With proper portable instruments and first-responder training, this is a technique that can potentially be used in the field to save lives from intra-abdominal exsanguination.

Abdominal Insufflation Decreases Blood Loss and Mortality after Porcine Liver Injury

BACKGROUND

Uncontrolled intra-abdominal bleeding is a common cause of death in trauma patients in the prehospital and perioperative settings. The detrimental effects of abdominal hypertension are well studied, but the potential therapeutic use of abdominal insufflation for hemostasis has not been fully explored. We measured the effect of abdominal insufflation on blood loss and physiologic outcomes in a swine model of blunt liver injury.

METHODS

Twenty-one anticoagulated swine (32 +/- 3 kg) were anesthesized; laparotomy was performed to localize liver anatomy and to place loose tourniquettes isolating the porta hepatis and supra/infrahepatic vena cava. A captive bolt gun was used to create a grade V hepatic laceration, producing massive parenchymal injury as well as complex tears of the middle and right hepatic veins. Animals were randomized into either control (n = 10) or abdominal insufflation at 20 cm H(2)O pressure (n = 11) groups. Crystalloid was used to maintain a mean arterial pressure of 30 mm Hg. Arterial pressure and other physiologic variables were recorded for 20 minutes. Animals were then sacrificed and blood loss measured.

RESULTS

Blood loss was 69% lower in insufflated animals compared with controls (384 +/- 51 versus 1252 +/- 88 cc, p < 0.001). After 20 minutes, insufflated animals had significantly higher mean arterial blood pressure (32.2 +/- 4.2 versus 21.2 +/- 4.0 mm Hg) and lower total resuscitation volume (195 +/- 83 versus 1356 +/- 95 cc). Three pigs died in the control group (30%), whereas no insufflated animals died (p < 0.05).

CONCLUSION

In a swine model of catastrophic blunt hepatic injury, abdominal insufflation significantly decreased blood loss and mortality.

Is Pneumoperitoneum Harmful During Intra-Abdominal Hemorrhage in Rats?

BACKGROUND

Laparoscopic surgical interventions are being used in trauma patients for diagnostic and therapeutic purposes, but there are limited studies on this subject. The effect of pneumoperitoneum during intra-abdominal hemorrhage has not been elucidated. The aim of this study was to investigate the hemodynamic, respiratory, and renal effects of pneumoperitoneum in the splenic injury/ hemorrhagic shock model in rats.

MATERIAL AND METHODS

In this study, 80 anesthetized Wistar male rats (294.5 +/- 31.2 g) were randomized into 2 main groups: nontraumatized (group A) and traumatized (group B). After initial preparation and monitoring, each group was divided according to the degree of pneumoperitoneum. The nontraumatized subgroups were A1, sham-operated; A2, 4-8 mm Hg; A3, 9-13 mm Hg; and A4, 14-18 mm Hg. The traumatized subgroups were B1, splenic injury without pneumoperitoneum; B2, B3, and B4, splenic injury with pneumoperitoneum at 4-8 mm Hg, 9-13 mm Hg, and 14-18 mm Hg, respectively. Mean arterial pressure, heart rate, and respiratory rate were monitored continuously. Blood samples were obtained for hemoglobin, hematocrit, arterial blood gases, and biochemical analyses. Twenty-four hour urine output was collected.

RESULTS

In group B4, pH, pCO2, and HCO3 levels were lower than in all other groups, while pCO2 and base deficit levels were significantly higher (P < 0.05). Both blood and urine analysis results showed that 24-hour urine output and the glomerular filtration rate of groups A4 and B4 were significantly lower (P < 0.05), while urinary osmolarity and fractional sodium excretion levels were significantly higher (P < 0.05).

CONCLUSION

High-pressure pneumoperitoneum in splenically traumatized rats amplifies acidosis, decreases urine output, decreases glomerular filtration rate, and increases urinary osmolarity and fractional sodium excretion significantly.

Is it wise not to think about intraabdominal hypertension in the ICU?

PURPOSE OF REVIEW

This review focuses on the available literature published in the past 2 years. MEDLINE and PubMed searches were performed using intraabdominal pressure, intraabdominal hypertension, and abdominal compartment as search items. The aim was to find an answer to the question: "Is it wise not to measure or even not to think about intraabdominal hypertension in ICU?"

RECENT FINDINGS

It is difficult to find a good gold standard for intraabdominal pressure measurement. Bladder pressure can be used as an intraabdominal pressure estimate provided it is measured in a reproducible way. Automated continuous intraabdominal pressure monitoring has recently become available. Key messages are (1). body mass index and fluid resuscitation are independent predictors of intraabdominal hypertension; (2). intraabdominal hypertension increases intrathoracic, intracranial, and intracardiac filling pressures; (3). transmural or transabdominal filling pressures combined with volumetric parameters better reflect preload; (4). volumetric target values need to be corrected for baseline ejection fractions; (5). intraabdominal hypertension decreases left ventricular, chest wall and total respiratory system compliance; (6). best positive end-expiratory pressure can be set to counteract intraabdominal pressure; (7). acute respiratory distress syndrome definitions should take into account best positive end-expiratory pressure and intraabdominal pressure but not wedge pressure; (8). lung protective strategies should aim at deltaPplat (plateau pressure - intraabdominal pressure); (9). intraabdominal hypertension causes atelectasis and increases extravascular lung water; (10). intraabdominal hypertension is an independent predictor of acute renal failure; (11). monitoring of abdominal perfusion pressure can be useful; and (12). intraabdominal hypertension triggers bacterial translocation and multiple organ system failure.

SUMMARY

The answer is that it is unwise not to measure intraabdominal pressure in the ICU or even not to think about it.