Septic shock

Immunomodulatory effects of anaesthetic sevoflurane in septic mouse model

Sepsis is one among the dangerous medical threat that is very much related to body’s immune system having no proper treatment for this condition. About19 million cases of sepsis have been recorded and out of which 5 million cases die every year. Sevoflurane other than controlling the depth of anaesthesia, it does have a vital role in immunomodulations. The study is focused on investigating the immunomodulatory effects of sevoflurane in the septic mouse model induced by CLP. Mortality rate, organ damage, inflammatory mediators, bacterial load, coagulopathy, hepto and renal functional changes, serum lactate, blood glucose, neutrophil sequestration and finally histopathological examination were investigated. The results were interesting that exposure to sevoflurane improves the polymicrobial abdominal sepsis outcome. Mice exposed to sevoflurane after CLP significantly improved outcomes of polymicrobial abdominal sepsis and reduced mortality by improving overall 7-day survival (83.3%) compared to mice without sevoflurane (no treatment group 16.6%) additionally decreasing the surrogate marker levels in the experimental sepsis animal model conducted. Our study suggests that the selection of certain anaesthetic drugs could be critical in the management of septic patients because their immunomodulatory effects could be large enough to affect sepsis pathophysiology.

Vitamin C alleviates acute enterocolitis in Campylobacter jejuni infected mice

Human foodborne infections with the zoonotic pathogen Campylobacter jejuni are on the rise and constitute a significant socioeconomic burden worldwide. The health-beneficial, particularly anti-inflammatory effects of vitamin C (ascorbate) are well known. In our preclinical intervention study, we assessed potential anti-pathogenic and immunomodulatory effects of ascorbate in C. jejuni-infected secondary abiotic IL-10-/- mice developing acute campylobacteriosis similar to humans. Starting 4 days prior peroral C. jejuni-infection, mice received synthetic ascorbate via the drinking water until the end of the experiment. At day 6 post-infection, ascorbate-treated mice harbored slightly lower colonic pathogen loads and suffered from less severe C. jejuni-induced enterocolitis as compared to placebo control animals. Ascorbate treatment did not only alleviate macroscopic sequelae of infection, but also dampened apoptotic and inflammatory immune cell responses in the intestines that were accompanied by less pronounced pro-inflammatory cytokine secretion. Remarkably, the anti-inflammatory effects of ascorbate pretreatment in C. jejuni-infected mice were not restricted to the intestinal tract but could also be observed in extra-intestinal compartments including liver, kidneys and lungs. In conclusion, due to the potent anti-inflammatory effects observed in the clinical murine C. jejuni-infection model, ascorbate constitutes a promising novel option for prophylaxis and treatment of acute campylobacteriosis.

Predictive factors of septic shock and mortality in neutropenic patients

Neutropenia is a major risk factor for developing a serious infection. Bacteremia still causes significant mortality among neutropenic patients with cancer. The purpose of this study was to identify risk factors for septic shock and for mortality in neutropenic patients with leukemia and bacteremia. Consecutive samples from 20 patients with acute myeloid leukemia and bacteremia were studied during a 1 year period (January-December 2003). All patients received empirical antibiotic therapies for febrile episodes using ceftazidime plus amikacin. About 110 neutropenic febrile episodes were noted: clinically documented 14.54%, microbiologically documented 16.36% and fever of unknown origin 69.09%. Gram-negative organism caused eight febrile episodes: Pseudomonas (5), Klebsiella (3). Gram-positive organism caused 10 episodes: Staphylococcus (6), Streptococci (2), Enterococci (2). Pulmonary infection accounted for 25% of clinically documented infections. About 14 of the 110 febrile episodes were associated with septic shock causing mortality in 7 patients. In a univariate analysis variables associated with septic shock were: pulmonary infection (OR = 17, p = 0.001), serum bicarbonate < 17 mmol/l (OR = 68, p < 0.001) and serum lactate >3 mmol/l (OR = 62, p < 0.001). Variables associated with mortality were: pulmonary infection (OR = 83, p < 0.001) and serum bicarbonate < 17 mmol/l (OR = 61, p < 0.001). In a multivariate analysis two variables were associated with septic shock: pulmonary infection (OR = 5, p = 0.043) and serum lactate >3 mmol/l (OR = 10, p = 0.003). An elevated serum lactate (>3 mmol/l) and low serum bicarbonate ( < 17 mmol/l) at the onset of bacteremia are useful biomarkers in predicting septic shock and mortality in neutropenic patients.

Effects of Pneumoperitoneum and LPS-induced Endotoxemia on Cerebral Perfusion Pressure in Pigs

Multitrauma patients commonly develop abdominal compartment syndrome, which is defined as the end result of sustained, uncorrected, intra-abdominal hypertension. We aimed to assess the effects of increased intra-abdominal pressure (IAP) upon intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in the presence or absence of lipopolysacharide (LPS)-induced endotoxemia using an experimental porcine model of pneumoperitoneum. Experimental procedures were approved by the Animal Care Review Committee of the National Veterinary Institute. Sixteen female pigs weighing 20 to 25 kg, aged 3 to 4 months were used. The animal model of increased IAP employed in our studies was produced with intraperitoneal administration of helium at 25 mm Hg under general anesthesia. After induction of pneumoperitoneum, 16 animals were randomly divided into 2 groups of 8 pigs each. One group received LPS intravenously (endotoxin group) and the second group received saline (control group). ICP, CPP, and hemodynamic variables were continuously monitored and recorded. A significant reduction of the cardiac output and concurrent increases in systemic vascular resistance and central venous pressure were observed in both groups after induction of pneumoperitoneum. ICP increased whereas CPP decreased significantly compared with baseline values in both groups after elevation of IAP. After LPS administration (endotoxin group), the cardiac output and mean arterial pressure decreased significantly. The CPP decreased further in the endotoxin group after LPS administration, whereas ICP remained unchanged. IAP increases produce significant increases in the ICP and decreases in the CPP in this animal model. LPS-induced endotoxemia further decreased CPP.

The angiotensin II receptor blocker candesartan improves survival and mesenteric perfusion in an acute porcine endotoxin model

BACKGROUND

Blockade of the angiotensin II type 1 (AT1) receptor has been demonstrated to ameliorate splanchnic hypoperfusion in acute experimental circulatory failure. This study focused on hemodynamic changes and survival in pigs treated with AT1 blockade prior to or during acute endotoxinemia.

METHODS

Escherichia coli lipopolysaccharide endotoxin was infused in anesthetized and mechanically ventilated pigs. Systemic, renal, mesenteric and jejunal mucosal perfusion as well as systemic oxygen and acid-base balance were monitored. The selective AT1 receptor blocker candesartan was administered prior to as well as during endotoxinemia. Control animals received the saline vehicle.

RESULTS

Pre-treatment with candesartan resulted in higher survival rate (83%, 10 out of 12 animals) compared with 50% (6 of 12) in control animals and 27% (3 of 11) in animals treated during endotoxinemia. Pre-treatment with candesartan resulted in higher cardiac output, mixed venous oxygen saturation, arterial standard base-excess, portal venous blood flow during endotoxin infusion compared with controls and animals treated during endotoxinemia. No adverse effects were found on neither systemic nor renal circulation.

CONCLUSION

The favorable results of AT1 receptor blockade prior to endotoxinemia are lost when blockade is established during endotoxinemia demonstrating the importance of the renin-angiotensin system and its dynamic involvement in acute endotoxinemic shock.

Influence of sepsis on minimum alveolar concentration of desflurane in a porcine model

The effect of sepsis on the minimum alveolar concentration of desflurane (MAC(DES)) in humans and other animals has not been reported previously. The aim of this study was to test the hypothesis that sepsis might alter MAC(DES) in a normotensive septic porcine model. Twenty-four young healthy pigs were premedicated with ketamine 10 mg kg(-1 )i.m and then anaesthesia was established with propofol 3 mg kg(-1) and the trachea was intubated. Baseline MAC(DES) in each pig was evaluated by pinching with a haemostat applied for 1 min to a rear dewclaw. MAC(DES) was determined by changing desflurane concentrations stepwise until purposeful movement appeared. Pigs were randomly assigned to two groups of 12 animals: the saline group received a 1 h i.v. infusion of saline solution while the sepsis group received a 1 h i.v. infusion of live Pseudomonas aeruginosa. Epinephrine and hydroxyethylstarch were used to maintain normotensive and normovolaemic haemodynamic status. In both groups, MAC(DES) was evaluated 5 h after infusion. Significant increases in heart rate, cardiac output, mean pulmonary artery pressure and pulmonary vascular resistance occurred in the sepsis group. MAC(DES) was 9.2% (95% confidence interval (CI) 6.8-10.6%) for the saline group and 6.7% (95% CI: 4.7-10.4) for the sepsis group (P<0.05). These data indicate that MAC(DES) is significantly decreased in this normotensive hyperkinetic septic porcine model.

Management of the septic patient in the operating room

Sepsis, severe sepsis, and septic shock represent the spectrum of physiological response to a variety of infecting pathogens. Multiple-organ dysfunction may result from widespread activation of inflammatory and antiinflammatory mechanisms. Intensive multiorgan support, effective antibiotic therapy, and eradication of the inciting source remain the cornerstones in the care of septic patients. Perioperative planning and management need to ensure the continuation of such care in addition to providing for the requirements of the given surgical procedure.

Influence of sepsis on sevoflurane minimum alveolar concentration in a porcine model

Sevoflurane is widely used in anaesthetic protocols for patients undergoing surgical procedures. However, there are no reports on the influence of sepsis on minimum alveolar concentration of sevoflurane (MAC(SEV)) in animals or in humans. The aim of this study was to test the hypothesis that sepsis could alter the MAC(SEV) in a normotensive septic pig model. Twenty young, healthy pigs were used. After they had received 10 mg kg(-1) of ketamine i.m. for premedication, anaesthesia was established with propofol 3 mg kg(-1) and the trachea was intubated. Sevoflurane was used as the sole anaesthetic agent. Baseline haemodynamic recording included electrocardiography, carotid artery blood pressure and a pulmonary thermodilution catheter. Baseline MAC(SEV) in each pig was evaluated by pinching with a haemostat applied for 1 min to a rear dewclaw. MAC(SEV) was determined using incremental changes in sevoflurane concentration until purposeful movement appeared. Pigs were assigned randomly to two groups: the saline group (n = 10) received a 1-h i.v. infusion of sterile saline solution while the sepsis group (n = 10) received a 1-h i.v. infusion of live Pseudomonas aeruginosa. Epinephrine and hydroxyethylstarch were used to maintain normotensive and normovolemic haemodynamic status. In both groups, MAC(SEV) was evaluated 5 h after infusion. Significant increases in mean artery pulmonary pressure, filling, epinephrine and vascular pulmonary resistances occurred in the sepsis group. MAC(SEV) for the saline group was 2.4% [95% confidence interval (CI) 2.1-2.55%] and the MAC(SEV) for the sepsis group was 1.35% (95% CI 1.2-1.45%, P<0.05). These data indicate that MAC(SEV) is significantly decreased in this normotensive septic pig model.

Severe group A streptococcal infection and streptococcal toxic shock syndrome

PURPOSE

To review the literature on group A streptococcal toxic shock syndrome, (STSS).

DATA SOURCE

Medline and EMBASE searches were conducted using the key words group A streptococcal toxic shock syndrome, alone and in combination with anesthesia; and septic shock, combined with anesthesia. Medline was also searched using key words intravenous immunoglobulin, (IVIG) and group A streptococcus, (GAS); and group A streptococcus and antibiotic therapy. Other references were included in this review if they addressed the history, microbiology, pathophysiology, incidence, mortality, presentation and management of invasive GAS infections. Relevant references from the papers reviewed were also considered. Articles on the foregoing topics were included regardless of study design. Non-English language studies were excluded. Literature on the efficacy of IVIG and optimal antibiotic therapy was specifically searched.

PRINCIPAL FINDINGS

Reports of invasive GAS infections have recently increased. Invasive GAS infection is associated with a toxic shock syndrome, (STSS), in 8-14% of cases. The STSS characteristically results in shock and multi-organ failure soon after the onset of symptoms, and is associated with a mortality of 33-81%. Many of these patients will require extensive soft tissue debridement or amputation in the operating room, on an emergency basis. The extent of tissue debridement required is often underestimated before skin incision.

CONCLUSIONS

Management of STSS requires volume resuscitation, vasopressor/inotrope infusion, antibiotic therapy and supportive care in an intensive care unit, usually including mechanical ventilation. Intravenous immunoglobulin infusion has been recommended. Further studies are needed to define the role of IVIG in STSS management and to determine optimal anesthetic management of patients with septic shock.

Hemodynamic effects of intermittent manual lung hyperinflation in patients with septic shock

OBJECTIVE

The purposes of this study were to investigate the hemodynamic changes induced by intermittent manual lung hyperinflation (MHI) and to assess if these changes are adverse enough to warrant prohibition of MHI as a routine procedure in the care of patients with septic shock.

DESIGN

The study's design was experimental prospective.

SETTING

The settings were university hospital intensive care units.

PATIENTS

Subjects included 13 consecutive mechanically ventilated patients with septic shock who met the inclusion criteria.

MEASUREMENTS AND RESULTS

Phasic MHI-related increments in mean inspiratory airway pressure were concordant to changes in mean pulmonary artery pressure (MPAP) (r(2) = 0.67) with a 0.6 mm Hg rise in MPAP per cm H(2)O airway pressure. The magnitude of MPAP changes was not reflected in magnitude of stroke volume index (SVI) (r(2) = 0.06). On average, MHI did not induce statistically significant hemodynamic changes and mean values returned to baseline level within 15 minutes. SVI during MHI increased slightly in 9 patients, from 37 +/- 15 (mean +/- SD) to 41 +/- 17 mL/m(2) (P <.05), and decreased in 4, from 60 +/- 10 to 50 +/- 14 mL/m(2) (not significant). Patients with an increase in SVI had lower baseline values for SVI, cardiac index, and left ventricular stroke work index (P <.05) and higher values for systemic vascular resistance index compared with patients with a decrease in SVI (P <.05). Left ventricular stroke work index was higher in patients with a decrease in SVI than in patients with an increase in SVI (52 +/- 9 vs 34 +/- 8; P <.05). Tidal volume increased from 499 +/- 176 mL before MHI to 587 +/- 82 mL, 5 minutes after MHI (P <.05) with a return to baseline values within 15 minutes after the procedure.

CONCLUSION

The hemodynamic effects of intermittent MHI in patients with septic shock are relatively small and insignificant and seem to be related to the cardiovascular state before the procedure. The risk of inducing hemodynamic changes with MHI should not be considered as a contraindication in patients with septic shock who are mechanically ventilated.

High adenosine plasma concentration as a prognostic index for outcome in patients with septic shock

OBJECTIVE

Sepsis and septic shock are a common cause of mortality in critically ill patients. Many substances have been implicated in the pathophysiology of these syndromes. We postulated that adenosine may be implicated in the sepsis- or septic shock-induced blood pressure failure. Indeed, this nucleoside is a strong endogenous vasodilating agent released by endothelial cells and myocytes under circumstances of metabolic stress, such as during critical illness.

DESIGN

A prospective, comparative observational study.

SETTING

The adult intensive care unit of a tertiary care university hospital.

PATIENTS

We measured adenosine plasma concentration (APC) in patients with severe sepsis (n = 11), in patients with septic shock (n = 14), in patients with hemorrhagic traumatic shock (n = 14), and in 12 healthy volunteers. APC was evaluated every 12 hrs over 3 days.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

At study entry, we found that APC was higher in patients with septic shock (mean +/- so = 8.4 +/-3.5 micromol/L) than in patients with hemorrhagic traumatic shock (1.1 +/- 0.6 micromol/L) and controls (0.8 +/- 0.3 micromol/L). Intermediate values (3.9 +/- 1.9 micromol/L) were found in patients with severe sepsis. APC in patients with traumatic shock did not differ from controls. In the course of the hospitalization, for both sepsis and septic shock patients, APC decreased significantly but remained higher than controls 72 hrs after entry into the study. In the septic shock group, APC was significantly higher in the nonsurvivor group (n = 6) than in the survivor group (n = 8), whatever the time of sample collection and assay.

CONCLUSIONS

High adenosine plasma concentrations are found in patients with septic shock but not during traumatic shock, or in healthy volunteers. Intermediate values of circulating adenosine are found in patients with severe sepsis. APC may be a prognostic index for outcome in septic patients, with much higher values being found in nonsurvivors.

The role of the vasculature in regulating venous return and cardiac output: historical and graphical approach

PURPOSE

To review the physiology of cardiac output regulation by the peripheral vasculature. This will enable the clinician to understand and manage the complex circulatory changes in various forms of shock, and in other common altered circulatory states encountered in anaesthetic practice.

SOURCE

Articles were obtained from a Medline review (1966 to present; search terms: shock, venous return, cardiac output) and a hand search (Index Medicus). Other sources include review articles, personal files, and textbooks.

PRINCIPAL FINDINGS

At steady state, cardiac output is equal to venous return (VR). Venous return depends on mean systemic pressure (PMS), which is the pressure in the peripheral vasculature driving blood flow to the heart, right atrial pressure (PRA), and the resistance to venous return (RV). When considering VR, PRA is the downstream pressure to VR, and not simply an indirect measure of the volume status. The pressure gradient for VR is, therefore, PMS-PRA, and in a system obeying Ohm's Law, [formula: see text] Shock and other altered circulatory states cause changes in both VR and cardiac function. The circulation can be conveniently described by a venous return and a cardiac output curve. By drawing these curves for each clinical situation, a clear understanding of the altered circulatory state is obtained, and treatment options can be clearly defined.

CONCLUSION

The peripheral circulation controls cardiac output in many clinical conditions. Manipulation of the peripheral circulation is as important to the successful treatment of shock and other altered circulatory states, as is the manipulation of cardiac output.