Hemodynamic effects of the laparoscopic pneumoperitoneum during sepsis in a porcine endotoxic shock model

Prospective, randomized, clinical trial on the effects of laparoscopic insufflation pressures on portal pressures in dogs

OBJECTIVE

The adverse effects of intra-abdominal pressure from capnoperitoneum on cardiovascular and pulmonary systems have been well documented, but the effects on portal pressures in dogs with various insufflation pressures is poorly defined. The aim of the present study was to measure the effect of a range of insufflation pressures on the portal pressure, using direct pressure measurements in patients undergoing laparoscopy.

STUDY DESIGN

Clinical randomized prospective study.

ANIMALS

Nine client-owned dogs undergoing routine laparoscopy.

METHODS

Two rounds of direct portal pressure assessments were performed, at insufflation pressures of 0, 6, 10, and 14 mmHg in a predetermined randomized sequence. The data were analyzed for effects of insufflation pressure, hemodynamic alterations, and round. A best-fit exponential model of the relationship between portal pressure and insufflation pressure was created.

RESULTS

Portal pressure increased by 38% at 6 mmHg, 95% at 10 mmHg, and 175% at 14 mmHg compared to baseline. Portal pressure increased at an average rate of 7.45% per mmHg of insufflation pressure. Effects of weight, weight/insufflation pressure interaction, and round of insufflation were not statistically significant. No systemic hemodynamic adverse events were observed.

CONCLUSION

Portal pressure increased as insufflation pressure increased. There was no clinically significant difference in baseline portal pressure between rounds of insufflation.

CLINICAL SIGNIFICANCE

This exponential model of portal pressure supports the use of the minimum insufflation pressure to allow visualization during laparoscopy. The return of portal pressure to baseline following desufflation supports the comparison of portal pressure measurements before and after laparoscopic shunt attenuation.

Variations of renal tissue oxygenation during abdominal compartment syndrome and sepsis

PURPOSE

This experimental study was designed to evaluate the renal tissue oxygenation under the coexistence of abdominal compartment syndrome and sepsis.

MATERIAL AND METHODS

Fourteen non-breed dogs were divided into two groups: the control group (8) and the study group (6). Sepsis was established with intravenous endotoxin infusion at 100μg/kg for over 30min. Insufflation of CO₂ in the peritoneal cavity was used for the increase in intra-abdominal pressure (IAP). A special catheter placed and fixed in the renal cortex at a depth of 3mm from the renal capsule was used for the measurement of renal tissue oxygenation.

RESULTS

Study parameters were recorded at the starting phase, at IAP of 15mmHg and 30mmHg and after decompression of the abdomen in the control group, and at the same intervals plus the induction of sepsis, prior to increasing abdominal pressure, in the study group. With the elevation of the IAP a reduction of renal tissue oxygenation presents itself, which is more pronounced in the presence of sepsis, especially for IAP over 15mmHg. Like other parameters, after abdominal decompression the renal tissue oxygenation returns to the initial levels, independently of sepsis.

CONCLUSIONS

The afferent arterioles vasoconstriction, which takes place during sepsis, and the intra-renal shunt, which occurs and leads to blood diversion to the medulla from the renal cortex due to the combination of intra-abdominal hypertension (IAH) and sepsis, seem to explain this finding.

The effects of pneumoperitoneum and controlled ventilation on peritoneal lymphatic bacterial clearance: experimental results in rats

OBJECTIVE

To evaluate the effect of pneumoperitoneum, both alone and in combination with controlled ventilation, on peritoneal lymphatic bacterial clearance using a rat bacterial peritonitis model.

METHOD

A total of 69 male Wistar rats were intraperitoneally inoculated with an Escherichia coli solution (10(9) colony-forming units (cfu)/mL) and divided into three groups of 23 animals each: A (control group), B (pneumoperitoneum under 5 mmHg of constant pressure), and C (endotracheal intubation, controlled ventilation, and pneumoperitoneum as in Group B). The animals were sacrificed after 30 min under these conditions, and blood, mediastinal ganglia, lungs, peritoneum, liver, and spleen cultures were performed.

RESULTS

Statistical analyses comparing the number of cfu/sample in each of the cultures showed that no differences existed between the three groups.

CONCLUSION

Based on our results, we concluded that pneumoperitoneum, either alone or in association with mechanical ventilation, did not modify the bacterial clearance through the diaphragmatic lymphatic system of the peritoneal cavity.

Selective application of laparoscopic intervention in the management of isolated bowel rupture in blunt abdominal trauma

BACKGROUND

Recently, laparoscopy has been used as an effective diagnostic and therapeutic modality for traumatic injury and peritonitis. However, its clinical benefits are still under evaluation. The aim of this study was to assess the feasibility and safety of this technique, in comparison with traditional laparotomy, in the management of isolated bowel rupture. A further aim was to evaluate possible predictive clinical factors in the management of isolated bowel rupture.

INDICATIONS

Patients with definite or suspected isolated gastrointestinal perforation who were hemodynamically stable underwent laparoscopic surgery for diagnosis and treatment.

METHODS AND RESULTS

The traditional laparotomy control group (Group A, historical controls) included patients from a prior study. In this previous study, carried out between 1993 and 1997, 23 consecutive cases of traumatic gastrointestinal perforation were treated with traditional laparotomy. Retrospectively, 13 of these 23 cases would have been eligible for laparoscopic intervention. The laparoscopic group (group B) was made up of cases seen at our institution from 1998 to 2000. Of the 13 consecutive cases of traumatic gastrointestinal perforation, only one required immediate traditional laparotomy. Just one of the 12 cases of gastrointestinal perforation approached laparoscopically had to be converted to a traditional laparotomy. The following variables were evaluated in both groups: patient background, time from accident to onset of operation, operative time, blood loss, time to oral intake, incidence of peritoneal contamination, length of hospital stay, mortality, and intraoperative and postoperative complications. There were no statistical differences in age, gender ratio, and injury severity score (ISS). The mean operative times were 132.3 +/- 58.7 minutes and 143.6 +/- 27.3 minutes in group A and group B, respectively. The mean blood loss was 266.8 +/- 277.8 mL in group A and 57.6 +/- 57.1 mL in group B. The blood loss in group B was significantly lower (P =.0084) than that in group A. There were no significant differences in intraoperative and postoperative complications, hospital stay, and mortality between the two groups.

CONCLUSIONS

Laparoscopic intervention offers better results in the management of patients with blunt abdominal trauma and isolated bowel rupture.

Colecistectomia laparoscópica em pacientes de alto risco

OBJETIVO: Relatar a experiência com a colecistectomia laparoscópica na colecistite aguda, em pacientes de alto risco (ASA 4). MÉTODO: De 1982 a 2001 foram realizadas, na Clínica Especializada em Doenças do Aparelho Digestivo (DIGEST), 1507 colecistectomias laparoscópicas, sendo 150 (10%) em colecistite aguda, dentre as quais 10 (0,7%) em pacientes ASA 4. RESULTADOS: Entre estes 10 pacientes observou-se uma faixa etária elevada com média de 70,9 anos (variando entre 50 e 89 anos), maior freqüência do sexo masculino (60%), período de internação pré-operatório bastante variável (de três a 22 dias), prevalência elevada de colecistite aguda alitiásica (30%) e grande freqüência de insuficiência renal (40%) dentre as doenças associadas. Como complicações de pós-operatório houve uma coleção sub-hepática tratada por drenagem guiada por ultrassonografia; duas infecções de sítio operatório, tratadas pela abertura da pele do portal infectado, e um óbito decorrente da perpetuação do quadro séptico em paciente previamente submetido a colecistostomia percutânea. Não houve necessidade de conversão em nenhum dos pacientes operados. CONCLUSÃO: Os autores concluem pela viabilidade do método laparoscópico no tratamento da colecistite aguda em pacientes de alto risco, observando-se algumas estratégias específicas.

Effects of pneumoperitoneum on hemodynamic and systemic immunologic responses to peritonitis in pigs

BACKGROUND

Experimental evidence supporting the safety of laparoscopic intervention during sepsis is limited. The purpose of this study was to evaluate the effects of pneumoperitoneum on immunologic and hemodynamic responses to peritoneal sepsis.

MATERIALS AND METHODS

A porcine model of peritonitis was created using an intraperitoneal autologous fecal inoculum. Pigs were then subjected to one of four procedures 24 h postinoculation (n = 6 per group): laparotomy, CO(2) laparoscopy, helium laparoscopy, and anesthesia only (1.5% isoflurane in 100% O(2), mechanical ventilation). Venous blood samples were obtained prior to inoculation, and at 24 (prior to procedure), 30, 48, 72, and 96 h postinoculation to determine white blood count (WBC) with differential, C-reactive protein (CRP), tumor necrosis factor, and bacteremia. Heart rate, end-tidal CO(2) (ETCO(2)), mean arterial blood pressure (MAP), and arterial blood gas variables were also measured at baseline and every 30 min throughout the procedure.

RESULTS

Postoperative blood cultures confirmed systemic bacteremia in all groups at all time periods postinoculation. Following inoculation, WBC, band cell count, and CRP remained elevated above baseline in all groups throughout the study (P < 0.01). However, no significant differences in these parameters were observed among groups. In the CO(2) laparoscopy group, MAP, ETCO(2), and arterial pCO(2) were increased above baseline, while pH was decreased throughout the procedure (P < 0.01).

CONCLUSIONS

In this animal model of peritonitis, CO(2) pneumoperitoneum induced hypercapnia, acidemia, and systemic hypertension intraoperatively, without a discernable effect on systemic immune function.

Bedside laparoscopy in the ICU: report of four cases

BACKGROUND

Patients in the intensive care unit (ICU) may suffer from life-threatening abdominal pathologies, which may necessitate a surgical intervention. Diagnosis may be difficult, as deep sedation and analgesia often mask symptoms, and physical examination is unreliable. Imaging studies are not accurate enough, and exploratory laparotomy carries significant morbidity and mortality rates in this patient population. The unstable patient is difficult to mobilize to the imaging department or to the operating room. Bedside laparoscopy may overcome these difficulties.

PATIENTS AND METHODS

We describe our initial experience with the use of bedside laparoscopy in critical patients with suspected abdominal pathology. The procedure was performed in four patients over a 4-month period and completed in all four.

RESULTS

The findings were: turbid fluid consistent with viscus perforation in a patient with unexplained sepsis after cardiac surgery, sterile hemorrhagic fluid in a patient with malignancy and thrombotic thrombocytopenia purpura, a retroperitoneal mass from which biopsies were taken in a patient with sudden respiratory failure, and abdominal abscess in a patient after bowel resection for mesenteric embolism. None of these patients had a laparotomy after the laparoscopy. Patients 1 and 4 died a few hours after the procedure from sepsis, and patients 2 and 3 died several days later.

CONCLUSION

Bedside laparoscopy in the ICU is feasible, informative, and accurate. It has a role in diagnosing abdominal pathologies and planning further treatment. It may avert a nontherapeutic laparotomy. Unfortunately, the prognosis in these patients is poor. Earlier use of this diagnostic modality may improve patient outcome.

[Chronic experimental bacteremia in Yucatan micropigs]

The Yucatan micropig has been used to develop an experimental model of chronic bacteremia. This animal exhibits clinical and biological characteristics that are close to those in humans, and the pharmacokinetic behaviours of many classes of drugs in this model are similar to those in man. Six adult female were intravenously inoculated with a mean Escherichia coli inoculum of 5.1 x 10(9) bacteria. During five days of spontaneous evolution, the medical follow-up includes biological, clinical and bacteriological parameters. A systemic inflammatory syndrome, a sepsis, an organ insufficiency and positive blood cultures mimic the human disease. In all animals there is an adynamia, a lack of motor coordination, an anorexia, a tachypnea, a fever, a leuconeutropenia followed by an hyperleucocytosis, an anemia, a thrombopenia, an acute tubulonephritis and an elevated sedimentation rate. In some cases, there is an increase of the C reactive protein, in others, an increase of IL-6 and IL-8. At day five, all animals are alive, and five micropigs have positive blood cultures. This chronic, reproducible model is thus suitable for further antibacterial treatments evaluations.

Effects of abdominal Co2 insufflation on renal and hepatic blood flows during acute hemorrhage in anesthetized pigs

OBJECTIVE

To evaluate the consequences of laparoscopy during hemorrhage, we studied the respiratory, renal, and hepatic blood flow changes induced by abdominal Co2 insufflation during severe hemorrhage in anesthetized pigs.

DESIGN

Prospective animal study.

SETTING

University research laboratory.

SUBJECTS

Anesthetized and ventilated pigs (n = 18).

INTERVENTIONS

The right carotid artery was cannulated to measure mean arterial pressure. A pulmonary artery catheter was inserted to measure mean pulmonary arterial pressure and cardiac output. After a midline abdominal incision, three flow probes were positioned around the portal vein, the hepatic artery, and the renal artery to measure portal vein blood flow, hepatic artery blood flow, and renal blood flow. To induce hemorrhage, blood was withdrawn until mean arterial pressure reached 50 mm Hg. Laparoscopy was mimicked by insufflating Co2 until intra-abdominal pressure reached approximately 15 mm Hg. Measurements were collected during hemorrhage, Co2 abdominal insufflation, and the combination of both interventions.

MEASUREMENTS AND MAIN RESULTS

Severe pulmonary hypertension and hypercapnic acidosis occurred during abdominal Co2 insufflation. However, the abdominal Co2 insufflation did not aggravate the cardiac output and total hepatic blood flow changes induced by acute hemorrhage, whereas the combination of hemorrhage and abdominal Co2 insufflation markedly altered renal blood flow.

CONCLUSIONS

These results suggest that renal function must be monitored carefully when performing laparoscopy in trauma patients. In contrast, hepatic perfusion seems well preserved.

Renal physiology. Laparoscopic considerations

Oliguria is a recognized component of the physiologic effect of increased intra-abdominal or retroperitoneal pressure. The cause is multifactorial, emanating from vascular and parenchymal compression, and is associated with systemic hormonal effects. Ureteral obstruction does not play a significant role. These changes are pressure-dependent and are usually not apparent until pressures reach 15 mm Hg or more. This effect is not associated with any histologic pathology or evidence of renal tubular damage. After the release of the pneumoperitoneum or pneumoretroperitoneum, the renal function and urine output return to normal with no long-term sequelae, even in patients with pre-existing renal disease. The entire operative team must understand the physiologic effects of CO2 insufflation, which allows appropriate intraoperative monitoring and management and minimizes intraoperative and postoperative complications.

Effects of CO2 insufflation and laparotomy on wound healing in mice

BACKGROUND

The aim of the present study was to evaluate the effects of laparotomy and CO2 insufflation on wound healing in a murine incisional wound healing model.

METHODS

Seventy-two male Swiss Albino mice were randomly allocated into three groups of control, laparotomy and CO2 insufflation. A transverse skin incision of 15 mm was made in the dorsum of each mouse, and four interrupted mattress sutures with 4.0 polypropylene thread were laid for wound closure. A median laparotomy was performed in the laparotomy group. CO2 insufflation was performed with an intra-abdominal pressure of 9 mmHg. The retained gas was evacuated from the abdominal cavity at the end of a 60-min period. Mice were killed on the 3rd, 7th and 15th postoperative days. The wound tensile strength and 5-hydroxyproline concentration in the wound tissue were measured.

RESULTS

Tensile strength of the incised skin increased as the post-incision period progressed. There was no significant difference between the tensile strengths of the incised skin of control, laparotomy and CO2 insufflation groups throughout the observation period. The skin 5-hydroxyproline concentrations of all groups were not significantly different at the 3rd postoperative day. But laparotomy and CO2 insufflation groups had lower 5-hydroxyproline concentrations at the 7th and 15th postoperative days, when compared to controls (P < 0.02 for 7th and 15th days).

CONCLUSION

CO2 insufflation and laparotomy reduce the 5-hydroxyproline concentration of the wound, suggesting a diminished wound healing capacity.

Description of an intraperitoneal tumour xenograft survival model in the pig

AIMS

Experimental animal studies are necessary if the results of minimally invasive oncological surgery are to be improved. In particular the influence of surgical technique on tumour implantation needs further assessment. Small animals such as rodents are inappropriate for such laparoscopic surgical studies. There is a requirement for another animal tumour model with animals greater in size.

METHODS

Accordingly we developed an intraperitoneal tumour xenograft survival model using the domesticated pig. After creating a 12 mmHg pneumoperitoneum, 10(7)human HeLa cells were injected into the peritoneal cavity of nine non-syngeneic animals to induce tumour xenograft. Resection of the sigmoid colon using four trocars and a transanal double-stapling technique was performed. The mean operating time was 69 min. No signs of post-operative pain symptoms were observed, and all the animals survived the procedure and gained weight. After 4 weeks, the animals were sacrified and all incision sites and anastomoses were excised.

RESULTS

Immunohistochemical staining with antihuman pancytokeratin antibodies confirmed tumour implants in 25 out of 36 port-sites (63.8%). No peritoneal carcinosis nor tumour implants at anastomosis sites were observed.

CONCLUSION

This intraperitoneal xenograft tumour model in the pig can be applied in survival studies to check the quality of surgical techniques and its influence on tumour implantation following laparoscopy for cancer.

Laparoscopic surgery and surgical infection

INTRODUCTION

It has been observed that the metabolic response to surgical injury is less after laparoscopic surgery than after open surgery. However, the effect of laparoscopic surgery on surgical infection has not been given much attention in the surgical literature, even though it may decrease the incidence of infectious complications. The objective of this study was to assess the influence that laparoscopic surgery has on surgical infection and to highlight certain controversial aspects.

METHODS

A review of the literature was undertaken to examine the relationship between laparoscopic surgery and surgical infection. This was achieved primarily by using PubMed Medline as a source of material.

RESULTS AND CONCLUSION

Laparoscopic surgery is associated with better preservation of the immune system than open surgery. This results in a decreased incidence of infectious complications. Although carbon dioxide pneumoperitoneum affects the peritoneal response to injury, it seems to have no harmful effect in terms of intra-abdominal infection. Nevertheless, at laparoscopic operation the virulence of intestinal micro-organisms should be recognized and, while knowing the advantages of minimally invasive surgery, the surgeon should consider the complexity of this technique. Furthermore, maintenance of laparoscopic instruments should be governed by the same norms as those used in open surgery; recommendations offered by the manufacturers should be respected.

Interventions to improve cardiopulmonary hemodynamics during laparoscopy in a porcine sepsis model

BACKGROUND

Laparoscopy is increasingly used in severely ill and acutely septic patients. In animals undergoing laparoscopy, the hemodynamic response to sepsis is blunted. Specific interventions to augment the hemodynamic potential may make laparoscopic intervention a safer alternative in septic patients. We compared different interventions to improve hemodynamic performance during exploratory laparoscopy in a porcine endotoxic shock model.

STUDY DESIGN

Domestic pigs (n = 12) received intravenous lipopolysaccharide injection and underwent surgical abdominal exploration using either laparoscopy or conventional laparotomy. For comparison, pigs exposed to endotoxin underwent laparoscopy with these interventions: intravenous infusions of prostacyclin (n = 5) or indomethacin (n = 4), intravenous crystalloid resuscitation (n = 5), pulmonary hyperventilation (n = 4), or abdominal insufflation with air (n = 5). Hemodynamic measurements and blood gas analyses were obtained using Swan-Ganz and arterial catheters.

RESULTS

Septic animals treated with prostacyclin undergoing laparoscopy had a higher cardiac index (CI, p < 0.01), stroke volume (SV; p < 0.001) and oxygen delivery (p < 0.05) than the untreated group. Likewise, treatment with indomethacin was associated with a higher CI (p < 0.001), SV (p < 0.005), and oxygen delivery (p < 0.005) compared with the untreated group. These effects may be secondary to a decreased pulmonary vascular resistance, demonstrated in the animals that received either prostacyclin (p < 0.05) or indomethacin (p < 0.05). In addition, animals given aggressive fluid resuscitation had a significantly higher CI (p < 0.05) and SV (p < 0.001) than those with normal fluid resuscitation during laparoscopy. Manipulation of arterial pH by insufflation of the abdomen with air to create the pneumoperitoneum, or by aggressively hyperventilating the animals, did not improve CI.

CONCLUSIONS

Adverse effects of laparoscopy on cardiovascular hemodynamics in the septic state may be mediated by increased pulmonary vascular resistance, diminished venous return, or both. Specific interventions to reverse these variables may ameliorate hemodynamic changes seen.

Gastrointestinal complications in the intensive care unit

Pathologic conditions affecting the abdomen are a significant cause of morbidity and mortality in the intensive care unit, but their importance is not widely recognized. This article presents several aspects of abdominal pathology that can occur in intensive care unit patients. This pathology may have a considerable impact on the prognosis and survival of the critically ill patient. The diagnostic contribution of laboratory tests and imaging is discussed. Conditions such as the abdominal compartment syndrome, acute mesenteric ischemia, gastrointestinal bleeding, diarrhea, abdominal sepsis, complications of entereal and parenteral nutrition, and ileus in critically ill patients are also reviewed.

Cardiopulmonary effects of the laparoscopic pneumoperitoneum in a porcine model of adult respiratory distress syndrome

BACKGROUND

Increasingly, laparoscopy is being used in critically ill patients in whom there is a question of intra-abdominal sepsis. We examine the cardiopulmonary effects of laparoscopy in a porcine model of adult respiratory distress syndrome (ARDS).

METHODS

Domestic pigs (n = 12) underwent saline lung lavage and subsequent surgical abdominal exploration using either laparoscopy or conventional laparotomy. Hemodynamic and respiratory measurements were obtained.

RESULTS

After pulmonary lavage, the two groups developed similarly diminished arterial pO2 (P <0.001), a worsened pulmonary shunt (P <0.001), and an increased alveolar-arterial oxygen gradient (P <0.001). The pulmonary compliance was significantly decreased in the animals undergoing laparoscopy (versus laparotomy, P <0.05). The mean pulmonary arterial pressure did not differ between the groups. The laparoscopic group had a higher pCO2 (not significant) and was more acidotic (P <0.05) than the laparotomy group. The laparoscopic animals had an increased heart rate (P <0.05), cardiac index (P <0.01), and oxygen delivery (P <0.005) as compared with the laparotomy group.

CONCLUSIONS

During laparoscopy, animals with ARDS demonstrate further compromise in pulmonary physiologic parameters but overall cardio-respiratory function is preserved.