In the postconference phase, the work was primarily focused on the finalization of the arguments/narrative to be included in the final MQTiPSS publications. This task was accomplished by teleconferences and electronic-based discussion among WGs using a modified Delphi method. Finally, a writing committee (formed at the conference) together with all participants developed an Executive Summary for MQTiPSS (reference to Executive Summary to be copublished in Shock) and three full-size publications (references to Part I and II papers to be simultaneously published in Shock). Each (of the three) publication focuses upon the deliberations of two related WGs; this current Part III paper provides detailed discussion on recommendations made for Fluid Resuscitation and Antimicrobial Therapy Endpoints.
These survey data clearly underline the need to define various minimum quality recommendations (displayed in Table 2 and addressed in detail below). Summarizing, adequate fluid administration is crucial during sepsis. Due to the loss of endothelial integrity within the capillary bed, the restoration of intravascular volume and, in consequence, the enhancement of tissue oxygenation represent the major aim of fluid therapy.
The conference discussed several specific recommendations for preclinical models of sepsis to advance the use of these models. The following recommendations and considerations from the Fluid Resuscitation Endpoints Working Group are numbered consecutively from the preceding companion papers and start with recommendation 14.
As the importance of fluid administration has been clearly demonstrated in the clinical setting, and volume resuscitation is a central part of established current human therapies (3), the incorporation of fluid resuscitation into animal sepsis studies should approximate that given to human care, thereby increasing the clinical relevance of such models. A large body of evidence exists in support of this apparently obvious concept. Fluid administration should thus be an essential part of the experimental design to separate sepsis-related events from pathological events resulting solely from a circulatory decline due to protracted hypovolemia (25–27). Furthermore, cardiovascular parameters are important determinants of (micro)perfusion and organ function, and thus strongly influence the applicability of the model. Fluid administration improves (at least partly) hypovolemia and alterations of perfusion pressure induced by anesthesia. Application of more complex and invasive monitoring techniques enhances comparability to the human setting (28–31). The hemodynamic profile of human sepsis is characterized by an initial hyperdynamic phase followed by a hypodynamic period. Thus, fluid resuscitation is needed in sepsis models to replicate the hyperdynamic cardiovascular state seen in the early, resuscitated phase of human sepsis (23, 32, 33). In addition, fluid resuscitation ensures a more standardized experimental environment, enables reproducible and comparable measurements, and is essential to ensure scientific quality (27, 34). Concerning the 3Rs principles, fluid administration is an effective means of reducing animal suffering and unnecessary mortality (35, 36).
In small animal models with limited intravenous access, both peritoneal and subcutaneous routes are frequently used for fluid resuscitation. Subcutaneous fluid bolus treatment, typically used in small animal models, simulates an intravenous continuous infusion rather than a bolus dose. For example, in geriatric patients subcutaneous rehydration has proved as effective as intravenous therapy (41). However, the subcutaneous route, despite its ease, has limitations, for example, the risk of variable absorption rates dependent on microperfusion disturbances occurring during sepsis (42). To avoid electrolytes moving from the intravascular space to the extravascular (subcutaneous) space, isotonic solutions are recommended for subcutaneous application. Considering irritation at the application locus, an unbuffered 0.9% saline with a pH of 5.0 is irritating and painful when administered subcutaneously. Buffered systems such as lactated Ringer's solution (pH: 6.5) or Plasmalyte (pH: 6.5–8.0) are less irritating and thus recommended for subcutaneous administration. However, to closely simulate the clinical setting, fluid resuscitation should ideally be given via the intravenous route. The miniaturization of experimental equipment enables a feasible use of i.v. catheters even in small rodents. If an i.v. line is absent, fluid is recommended to be administered in intermittent repetitive doses, preferentially via an intraperitoneal route, to correct or prevent hypovolemia (35).
To avoid both fluid deficit and fluid overload, appropriate monitoring of therapeutic interventions is needed.
Hemodynamic monitoring guides not only therapeutic interventions, but also the diagnosis of shock, assessment of volume status, fluid responsiveness, and the need for vasopressor and/or inotropic support. However, only few experimental settings offer broad hemodynamic monitoring. For example, echocardiography in a murine sepsis model demonstrated that a hyperdynamic state could be achieved with adequate fluid resuscitation (23). In a fluid resuscitated long-term (3 days) rodent model of sepsis, outcome could be determined from early hemodynamic readouts. Significant differences in stroke volume and heart rate measured 6 h postinsult predicted 3-day mortality with high accuracy (48). Other monitoring methods include (1) pressure-volume catheter measurements for comprehensive cardiac hemodynamics, (2) transit-time volume flow measurement in blood vessels, (3) ultrasound-dilution for cardiac function and blood volume measurements, (4) noninvasive Doppler flow velocity measurements to assess cardiac output, filling, and ejection velocities, and (5) ultrasonic pulse wave velocity which can be determined in large and small animals. As a standard for freely moving rodents, radiotelemetry or mobile tethered systems can be used for blood pressure, oxygenation, temperature, and other physiological parameters. Microcirculatory monitoring can be performed by sidestream dark field imaging, laser Doppler, or laser speckle contrast-based techniques, and is typically performed under anesthesia in a variety of vascular beds (49).
SSC guidelines suggest that, when available, dynamic variables should be used over static variables to predict fluid responsiveness (3). Elevation of central venous pressure correlates with an exponential rise of pressures in the right atrium, and thus CVP-driven protocols are at risk of causing cardiac failure (47). In a meta-analysis Marik et al. could not show that a static CVP value predicts fluid responsiveness (50). In addition, elevated CVP correlated to acute renal failure in sepsis (49). MAP-driven strategies also failed to show advantages over perfusion-driven protocols in reducing morbidity and mortality (51–54).
The decision whether to administer fluid or not can be best guided by using dynamic variables such as pulse pressure variation, stroke volume variation, or the passive leg raising test (19–21, 25, 26), all of which can be realistically applied at present to anesthetized large animals only. Besides hemodynamic parameters, lactate clearance can be considered for the guidance of fluid therapy (55) as it correlates with the success of fluid therapy. Functional hemodynamics have been described to a very limited extent in animal models of sepsis; validation of this approach has been mainly reported in large animal models assessing the response to a fluid challenge. In both normo- and hypovolemic conditions of LPS-induced rat pneumonia, peripherally derived pulse pressure variation (PPV) was not reflected by centrally measured stroke volume variation (SVV) in the setting of increased total arterial compliance (56). In conclusion, it appears reasonable to transfer the recent clinical findings in the field of intravenous volume therapy to animal models, with preference given to dynamic rather than static hemodynamic monitoring (57).
Administration of 0.9% (physiological) saline may result in metabolic acidosis as a result of chloride overload (58, 59). The mechanism of this so-called “hyperchloremic acidosis,” which occurs despite the alkalizing effect of hemodilution-induced hypoalbuminemia (58), is the result of the interplay between an extracellular strong ion difference and the concentration of nonvolatile weak acids (58, 60). Fluid resuscitation with saline aggravated organ injury and increased mortality in rodent models of hemodilution (61) and sepsis (59). This suggests that iso-osmolar balanced crystalloid solutions rather than saline should be used for resuscitation. Although its role in human sepsis/septic shock is not yet definitely settled (62), albumin should be the only colloid resuscitation fluid used, accompanied by adequate monitoring of proteinemia and/or albuminemia. Finally, given the fundamentally different metabolic response to stress in rodents (63–65), attention should be paid to avoid hypoglycemia. Depending on the underlying hypothesis to be investigated, vasopressor and/or inotropic support should be used to allow for “… experiments with more advanced supportive care…” which “… would allow for better mimicry of …multi-organ failure…” (66).
Consistent with clinical practice, we recommend that antimicrobials be considered for preclinical studies assessing potential human therapeutics (Table 4). The inclusion of appropriate antimicrobials should allow for assessment of such therapies under clinically relevant conditions. However, as discussed below, it is important to recognize that some antimicrobials can impact significantly on the host which should be taken into account when designing a given study. Finally, there may be experimental situations that make it unnecessary or even inappropriate to use antimicrobials, or that preclude use of a specific agent. Examples include studies testing the antimicrobial properties of an experimental agent, or mechanistic studies designed to understand a pathway or the role of a specific mediator.
Adequate early source control and early administration of appropriate antimicrobials are considered central to the management of human sepsis (3). Source control is, however, rarely undertaken in preclinical sepsis studies, the majority of which involve peritoneal contamination with bacteria and abscess formation (e.g., CLP model). Although the benefit of early, appropriate antimicrobials may not be so great as generally supposed (74), it is nevertheless a standard of care in clinical practice that antimicrobials should be administered promptly (3). Administration of antimicrobials is therefore recommended when studying putative therapeutics, as they are routinely administered in humans with sepsis (3). The routine administration of antimicrobials in sepsis models may alter the efficacy of the therapeutic agent being evaluated, perhaps offering synergism (75–80). Thus, the absence of an antibiotic treatment arm may potentially skew the final conclusions. Studies in animal models do show improved survival with antibiotic treatment (23, 81–83). However, the impact is minimal or absent in aged animals (81), which are more reflective of human septic populations that are heavily skewed toward the elderly. It is also important to define an optimal dosing regimen to provide adequate but not excessive dosing of antimicrobials over the duration of the experiment, a topic that is also pertinent to human ICU patients (83, 84). Shorter duration therapy has been shown to be effective in the CLP model (83). Antimicrobial dosing will likely be both species- and insult severity-dependent. This should ideally take into account the altered pharmacokinetics that occur during sepsis, for example, related to altered metabolism and excretion, volumes of distribution and protein binding and, potentially, augmented renal clearance (85). Antibiotic pharmacodynamics are generally poorly understood in sepsis (85, 86) and are not well characterized in animal models.
Antimicrobial toxicity is increasingly recognized, even in healthy subjects. Antimicrobials affect the microbiome, modulate inflammatory pathways and immune function, bind and neutralize bacterial toxins such as LPS, affect cellular metabolism and mitochondrial function, and can affect the CNS (82, 87–93). These effects may be potentially amplified during sepsis. Antimicrobials have also been postulated to augment sepsis pathophysiology by generating Jarisch-Herxheimer reactions and cytokine release that are well described with first dose administration, particularly of cidal antibiotics that destroy the bacterial cell wall (94). The large-scale, rapid release of cell constituents such as endotoxin and DNA can significantly enhance the host PAMP (pathogen-associated microbial pattern) inflammatory response. However, the functional relevance of antibiotic-induced endotoxin release in animal models is unclear (95). Although improving survival, cidal antibiotics temporarily increased inflammation and worsened acute kidney injury in an experimental sepsis model (82). Further study is needed in these areas to better understand the benefits and risks of antimicrobial therapy, and establishment of correct dosing regimens.
In humans, the failure to provide appropriate antimicrobial therapies expeditiously has been associated with increased morbidity and mortality (96–98). Antimicrobials for animal studies should be chosen with careful attention to the particular model being used for a given study and the causative pathogen (s). The timing of the first dose of antimicrobials should also be chosen carefully (see also R-18), taking into account that the interval between the exposure (to pathogen) to the development of clinical infection varies between infections (e.g., pneumonia, peritonitis, primary bacteremia, fungal infection). Thus, in some situations it may be appropriate to provide antimicrobials early (e.g., a Neisseria-induced meningococcal model), whereas delayed administration may be appropriate for other models (e.g., polymicrobial CLP peritonitis).
Although it may not be feasible to fully recreate the antimicrobial choices given to humans, whenever possible it is recommended that the same or equivalent agents be used. The SCC guidelines recommend that antimicrobials be tailored to the pathogen (s), which vary widely between patients (3). A similar approach should be considered in animal sepsis models, with individualization of the antimicrobial regimen based on the likely specific pathogen(s). Several basic concepts of antimicrobial treatment follow.
Models involving monomicrobial bacterial infection should be treated with a single antibiotic that likely covers the pathogen. For instance, methicillin-sensitive Staphylococcus aureus can be treated with an appropriate ß-lactam, but methicillin-resistant S. aureus should be treated with vancomycin or similar. Escherichia coli could be treated with a second or third generation cephalosporin or an aminoglycoside. Polymicrobial infections, such as would be expected to arise from bowel perforation (e.g., CLP and CASP models) or fecal slurry injection, can be treated with either a broad-spectrum single agent such as a carbapenem, or a combination of agents that cover gram-positive and gram-negative aerobic and anaerobic bacteria. Fungal infections should be treated with an appropriate antifungal agent. Antimicrobial resistance for a given pathogen should be factored into decisions about antimicrobials.
The site of infection may also influence the choice of antimicrobial agent. Some antimicrobials are not effective for certain infections despite in vitro pathogen sensitivity. For instance, aminoglycosides are inactivated by low pH, and thus may not be effective for treating abscesses (99). Similarly, antimicrobials that do not effectively cross the blood brain barrier may be inappropriate for CNS infections. Finally, whether an antibiotic is cidal versus static may also be an important factor; cidal antibiotics are often chosen for life-threatening human infections, and thus may be appropriate for animal models.
Finally, minimum inhibitory concentrations (MICs) are used by diagnostic laboratories to assess the resistance of microbes to antimicrobial agents (susceptible, intermediate-susceptible and resistant) (100). As compared with non-ICU settings, infections in ICU patients are often caused by pathogens with higher MICs. Often the MIC of a specific strain of bacteria is known. However, if the pathogen's MIC is not known, consideration should be given to defining the MIC before initiating a study. This certainly cannot be demanded within current standard experimental settings but could be considered when specific microbial research aims are tested.
Whenever antimicrobials are included in a study, we recommend that their administration mimics clinical practice as closely as possible. The following factors should be considered when deciding on how to administer antimicrobials for a given study.
Antimicrobial pharmacokinetics differ between species. For example, the elimination half-life of cephalosporins was shorter in mice and rats versus rabbits, dogs, and monkeys (101). Clearance of garenoxacin differed in rats, dogs, and monkeys (102), whereas absorption of moxifloxacin was more rapid in rats, dogs, and humans than in monkeys and minipigs (103).
Numerous factors contribute to the altered pharmacology of antimicrobial agents in septic critically ill patients (104–108). These include an increased volume of distribution, altered protein binding, fluctuations in plasma clearance, the presence of edema which can limit the absorption of drugs, and drug-drug interactions (109–111). These alterations can lead to lesser or higher levels of drug exposure (108, 112). Optimal antimicrobial dosing regimens for human sepsis have still not been established. For instance, although broad-spectrum β-lactam antibiotics are considered appropriate for the treatment of ICU-acquired pneumonia (113) optimal administration (e.g., intermittent dosing vs. continuous infusion) remains uncertain (114, 115).
Advanced age, sex, and comorbidities are among the most important contributors to mortality in both septic patients and animal models (81, 116–120). These factors impact upon pharmacokinetics and pharmacodynamics of antimicrobials, but this is poorly characterized in animal models. Preclinical sepsis studies using two-hit models and/or various comorbidities potentially constitute an attractive, clinically translatable testing platform for establishing the influence of such factors upon the efficacy of antimicrobial treatment regimens.
Currently, many animal studies provide antimicrobials immediately or within a few hours following the infectious insult—the period in which clinical symptoms of sepsis are either absent or mild. However, patients are seldom treated in this early window given that antimicrobial treatment is typically triggered at the emergence of clear clinical symptoms. This makes the early administration of antimicrobials less replicative of the human condition (3). Furthermore, late provision of antibiotics starting 12 h after severe infection has been reported to allow animals to develop organ dysfunction (44). This suggests that delayed dosing may reasonably replicate the human condition as well as modulating the severity of the sepsis model itself. As discussed in the Part I companion paper (chapter 1; reference to Part I paper to be simultaneously published in Shock), there is uncertainty about the time course of sepsis in animal models relative to humans. For instance, interspecies differences in the interval between exposure to a pathogen and the development of clinical infection are poorly understood. Factors that differ between species, such as metabolic rates (accelerated in healthy rodents compared to bigger species) and differences in leukocyte distributions could profoundly affect responses to a bacterial insult. Additionally, quorum sensing bacteria may behave differently between species. Thus, it is conceivable that bacteria differentially express virulence genes and/or have different proliferation rates in different species. Finally, many animal studies use highly lethal models (e.g., high doses of pathogen, 2-hit models) which leads to an earlier onset and more rapid progression of sepsis than seen in patients. These issues make it difficult to recommend definitive time points for initiating antibiotics. Treatment should however be initiated soon after the animal manifests clinical signs of sepsis (e.g., lethargy, decreased locomotion, changes in body temperature).
The evidence base underlying benefit from early antimicrobial administration has been criticized (74). A systematic review and meta-analysis showed no significant mortality benefit from administering antibiotics within 3 h of emergency department triage or within 1 h of shock recognition in severe sepsis and septic shock (121). Despite differences in conclusions of various studies, the current standard of care in patients is to provide the first dose of antimicrobials as early as possible after diagnosing sepsis (i.e., organ dysfunction). It is thus reasonable to use a similar strategy for animal studies (122), particularly if the goal is to mimic current clinical practice. In future sepsis modeling scenarios, the administration of antimicrobials could be matched to the emergence of specific symptoms (that typically prompt evaluation/diagnosis in patients) rather than by the defined number of hours after an insult. There may be other experimental goals that factor into decisions regarding the timing of antimicrobials.
This Part III manuscript details the recommendations and considerations of two of the six working groups from the 2017 Wiggers-Bernard conference on preclinical models of sepsis. Analysis of the top-cited preclinical sepsis papers showed substantial heterogeneity with regard to the use of fluid resuscitation and antimicrobial treatment. A number of factors come into play when deciding on antimicrobial and fluid administration in animal sepsis studies. These include the goals of the experiment, the specifics of the model (microorganism, site of infection, comorbidities such as renal or liver dysfunction, age), and the animal species being used. Whenever antimicrobial agents or fluids are administered in a preclinical study, we recommend their administration mimics clinical practice as closely as possible. It is hoped that the proposed set of recommendations and considerations will serve to bring a level of standardization to preclinical models of sepsis and, ultimately, improve translatability of preclinical findings. We acknowledge that new challenges based on new information from the clinical and bench studies will continue to arise. A close collaborative work between basic scientists and clinicians is critical for a thoughtful (re)interpretation of any existing and newly posited principles.
1. Seymour CW, Liu VX, Iwashyna TJ, Brunkhorst FM, Rea TD, Scherag A, Rubenfeld G, Kahn JM, Shankar-Hari M, Singer M, et al. Assessment of clinical criteria for sepsis
: for the third international consensus definitions for sepsis
and septic shock
2016; 315 8:762–774.
2. Singer M, Deutschman CS, Seymour CW, Shankar-Hari M, Annane D, Bauer M, Bellomo R, Bernard GR, Chiche JD, Coopersmith CM, et al. The third international consensus definitions for sepsis
and septic shock
2016; 315 8:801–810.
3. Rhodes A, Evans LE, Alhazzani W, Levy MM, Antonelli M, Ferrer R, Kumar A, Sevransky JE, Sprung CL, Nunnally ME, et al. Surviving sepsis
campaign: international guidelines for management of sepsis
and septic shock
: 2016. Intensive Care Med
2017; 43 3:304–377.
4. Yealy DM, Kellum JA, Huang DT, Barnato AE, Weissfeld LA, Pike F, Terndrup T, Wang HE, Hou PC, LoVecchio F, et al. A randomized trial of protocol-based care for early septic shock
. N Engl J Med
2014; 370 18:1683–1693.
5. Peake SL, Delaney A, Bailey M, Bellomo R, Cameron PA, Cooper DJ, Higgins AM, Holdgate A, Howe BD, Webb SA, et al. Goal-directed resuscitation for patients with early septic shock
. N Engl J Med
2014; 371 16:1496–1506.
6. Mouncey PR, Osborn TM, Power GS, Harrison DA, Sadique MZ, Grieve RD, Jahan R, Harvey SE, Bell D, Bion JF, et al. Trial of early, goal-directed resuscitation for septic shock
. N Engl J Med
2015; 372 14:1301–1311.
7. Bouchard J, Mehta RL. Fluid balance issues in the critically ill patient. Contrib Nephrol
8. Kelm DJ, Perrin JT, Cartin-Ceba R, Gajic O, Schenck L, Kennedy CC. Fluid overload in patients with severe sepsis
and septic shock
treated with early goal-directed therapy is associated with increased acute need for fluid-related medical interventions and hospital death. Shock
2015; 43 1:68–73.
9. Seok J, Warren HS, Cuenca AG, Mindrinos MN, Baker HV, Xu W, Richards DR, McDonald-Smith GP, Gao H, Hennessy L, et al. Genomic responses in mouse models poorly mimic human inflammatory diseases. Proc Natl Acad Sci USA
2013; 110 9:3507–3512.
10. Remick D. Use of animal models for the study of human disease—a shock society debate. Shock
2013; 40 4:345–346.
11. Remick DG, Ayala A, Chaudry IH, Coopersmith CM, Deutschman C, Hellman J, Moldawer L, Osuchowski MF. Premise for standardized sepsis
12. Osuchowski MF, Thiemermann C, Remick DG. Sepsis
-3 on the block: what does it mean for preclinical sepsis
2017; 47 5:658–660.
13. Levy MM, Fink MP, Marshall JC, Abraham E, Angus D, Cook D, Cohen J, Opal SM, Vincent JL, Ramsay G. 2001 SCCM/ESICM/ACCP/ATS/SIS International Sepsis
Definitions Conference. Crit Care Med
2003; 31 4:1250–1256.
14. Levy MM, Fink MP, Marshall JC, Abraham E, Angus D, Cook D, Cohen J, Opal SM, Vincent JL, Ramsay G. 2001 SCCM/ESICM/ACCP/ATS/SIS International Sepsis
Definitions Conference. Intensive Care Med
2003; 29 4:530–538.
15. Shankar-Hari M, Phillips GS, Levy ML, Seymour CW, Liu VX, Deutschman CS, Angus DC, Rubenfeld GD, Singer M. Developing a new definition and assessing new clinical criteria for septic shock
: for the third international consensus definitions for sepsis
and septic shock
2016; 315 8:775–787.
16. Kleinman ME, Goldberger ZD, Rea T, Swor RA, Bobrow BJ, Brennan EE, Terry M, Hemphill R, Gazmuri RJ, Hazinski MF, et al. 2017 American Heart Association Focused Update on Adult Basic Life Support and Cardiopulmonary Resuscitation Quality: an update to the American Heart Association Guidelines for Cardio pulmonary Resuscitation and Emergency Cardiovascular Care. Circulation
2017; 137 1:e7–e13.
17. Davis AL, Carcillo JA, Aneja RK, Deymann AJ, Lin JC, Nguyen TC, Okhuysen-Cawley RS, Relvas MS, Rozenfeld RA, Skippen PW, et al. American College of Critical Care Medicine Clinical Practice Parameters for Hemodynamic Support of Pediatric and Neonatal Septic Shock
. Crit Care Med
2017; 45 6:1061–1093.
18. de Carvalho H, Matos JA, Bouskela E, Svensjö E. Vascular permeability increase and plasma volume loss induced by endotoxin was attenuated by hypertonic saline with or without dextran. Shock
1999; 12 1:75–80.
19. Rahal L, Garrido AG, Cruz RJ Jr, Silva E, Poli-de-Figueiredo LF. Fluid replacement with hypertonic or isotonic solutions guided by mixed venous oxygen saturation in experimental hypodynamic sepsis
. J Trauma
2009; 67 6:1205–1212.
20. Garrido AG, Poli de Figueiredo LF, Cruz RJ Jr, Silva E. Rocha e Silva: Short-lasting systemic and regional benefits of early crystalloid infusion after intravenous inoculation of dogs with live Escherichia coli
. Braz J Med Biol Res
2005; 38 6:873–884.
21. van Haren FM, Sleigh JW, Pickkers P, van der Hoeven JG. Gastrointestinal perfusion in septic shock
. Anaesth Intensive Care
2007; 35 5:679–694.
22. Byrne L, Van HF. Fluid resuscitation
in human sepsis
: time to rewrite history? Ann Intensive Care
2017; 7 1:4.
23. Hollenberg SM, Dumasius A, Easington C, Colilla SA, Neumann A, Parrillo JE. Characterization of a hyperdynamic murine model of resuscitated sepsis
using echocardiography. Am J Respir Crit Care Med
2001; 164 5:891–895.
24. Byrne L, Obonyo NG, Diab S, Dunster K, Passmore M, Boon AC, Hoe LS, Hay K, Van HF, Tung JP, et al. An ovine model of hyperdynamic endotoxemia and vital organ metabolism. Shock
2018; 49 1:99–107.
25. Cornelius DC, McCalmon M, Tharp J, Puskarich M, Jones AE. Fluid resuscitation
in animal models of sepsis
: a comprehensive review of the current state of knowledge. Arch Emerg Med Crit Care
2016; 1 1:1002.
26. Natanson C, Danner RL, Reilly JM, Doerfler ML, Hoffman WD, Akin GL, Hosseini JM, Banks SM, Elin RJ, MacVittie TJ, et al. Antibiotics versus cardiovascular support in a canine model of human septic shock
. Am J Physiol
1990; 259 ((5 Pt. 2)):H1440–H1447.
27. Zanotti-Cavazzoni SL, Guglielmi M, Parrillo JE, Walker T, Dellinger RP, Hollenberg SM. Fluid resuscitation
influences cardiovascular performance and mortality in a murine model of sepsis
. Intensive Care Med
2009; 35 4:748–754.
28. Buras JA, Holzmann B, Sitkovsky M. Animal models of sepsis
: setting the stage. Nat Rev Drug Discov
2005; 4 10:854–865.
29. Fink MP, Heard SO. Laboratory models of sepsis
and septic shock
. J Surg Res
1990; 49 2:186–196.
30. Freise H, Bruckner UB, Spiegel HU. Animal models of sepsis
. J Invest Surg
2001; 14 4:195–212.
31. Deitch EA. Animal models of sepsis
and shock: a review and lessons learned. Shock
1998; 9 1:1–11.
32. Albuszies G, Radermacher P, Vogt J, Wachter U, Weber S, Schoaff M, Georgieff M, Barth E. Effect of increased cardiac output on hepatic and intestinal microcirculatory blood flow, oxygenation, and metabolism in hyperdynamic murine septic shock
. Crit Care Med
2005; 33 10:2332–2338.
33. Barth E, Radermacher P, Thiemermann C, Weber S, Georgieff M, Albuszies G. Role of inducible nitric oxide synthase in the reduced responsiveness of the myocardium to catecholamines in a hyperdynamic, murine model of septic shock
. Crit Care Med
2006; 34 2:307–313.
34. Doi K, Leelahavanichkul A, Yuen PS, Star RA. Animal models of sepsis
-induced kidney injury. J Clin Invest
2009; 119 10:2868–2878.
35. Lilley E, Armstrong R, Clark N, Gray P, Hawkins P, Mason K, Lopez-Salesansky N, Stark AK, Jackson SK, Thiemermann C, et al. Refinement of animal models of sepsis
and septic shock
2015; 43 4:304–316.
36. Nemzek JA, Hugunin KM, Opp MR. Modeling sepsis
in the laboratory: merging sound science with animal well-being. Comp Med
2008; 58 2:120–128.
37. Hilton AK, Bellomo R. A critique of fluid bolus resuscitation in severe sepsis
. Crit Care
2012; 16 1:302.
38. Sankar J, Ismail J, Sankar MJ, CPS, Meena RS. Fluid bolus over 15-20 versus 5-10 minutes each in the first hour of resuscitation in children with septic shock
: a randomized controlled trial. Pediatr Crit Care Med
2017; 18 10:e435–e445.
39. Ukor IF, Hilton AK, Bailey MJ, Bellomo R. The haemodynamic effects of bolus versus slower infusion of intravenous crystalloid in healthy volunteers. J Crit Care
40. Rudorfer MV, Manji HK, Potter WZ. Bupropion, ECT, and dopaminergic overdrive. Am J Psychiatry
1991; 148 8:1101–1102.
41. Slesak G, Schnurle JW, Kinzel E, Jakob J, Dietz PK. Comparison of subcutaneous and intravenous rehydration in geriatric patients: a randomized trial. J Am Geriatr Soc
2003; 51 2:155–160.
42. Dyson A, Singer M. Animal models of sepsis
: why does preclinical efficacy fail to translate to the clinical setting? Crit Care Med
2009; 37 (1 Suppl.):S30–S37.
43. Fink MP. Animal models of sepsis
2014; 5 1:143–153.
44. Steele AM, Starr ME, Saito H. Late therapeutic intervention with antibiotics and fluid resuscitation
allows for a prolonged disease course with high survival in a severe murine model of sepsis
2017; 47 6:726–734.
45. Lewis AJ, Yuan D, Zhang X, Angus DC, Rosengart MR, Seymour CW. Use of biotelemetry to define physiology-based deterioration thresholds in a murine cecal ligation and puncture model of sepsis
. Crit Care Med
2016; 44 6:e420–e431.
46. Hoste EA, Maitland K, Brudney CS, Mehta R, Vincent JL, Yates D, Kellum JA, Mythen MG, Shaw AD. Four phases of intravenous fluid therapy: a conceptual model. Br J Anaesth
2014; 113 5:740–747.
47. Marik P, Bellomo R. A rational approach to fluid therapy in sepsis
. Br J Anaesth
2016; 116 3:339–349.
48. Rudiger A, Dyson A, Felsmann K, Carre JE, Taylor V, Hughes S, Clatworthy I, Protti A, Pellerin D, Lemm J, et al. Early functional and transcriptomic changes in the myocardium predict outcome in a long-term rat model of sepsis
. Clin Sci (Lond)
2013; 124 6:391–401.
49. Obonyo NG, Fanning JP, Ng AS, Pimenta LP, Shekar K, Platts DG, Maitland K, Fraser JF. Effects of volume resuscitation on the microcirculation in animal models of lipopolysaccharide sepsis
: a systematic review. Intensive Care Med Exp
2016; 4 1:38.
50. Marik PE, Cavallazzi R. Does the central venous pressure predict fluid responsiveness? An updated meta-analysis and a plea for some common sense. Crit Care Med
2013; 41 7:1774–1781.
51. Lamontagne F, Meade MO, Hebert PC, Asfar P, Lauzier F, Seely AJE, Day AG, Mehta S, Muscedere J, Bagshaw SM, et al. Higher versus lower blood pressure targets for vasopressor therapy in shock: a multicentre pilot randomized controlled trial. Intensive Care Med
2016; 42 4:542–550.
52. Beloncle F, Radermacher P, Guerin C, Asfar P. Mean arterial pressure target in patients with septic shock
. Minerva Anestesiol
2016; 82 7:777–784.
53. Asfar P, Meziani F, Hamel JF, Grelon F, Megarbane B, Anguel N, Mira JP, Dequin PF, Gergaud S, Weiss N, et al. High versus low blood-pressure target in patients with septic shock
. N Engl J Med
2014; 370 17:1583–1593.
54. Dunser MW, Ruokonen E, Pettila V, Ulmer H, Torgersen C, Schmittinger CA, Jakob S, Takala J. Association of arterial blood pressure and vasopressor load with septic shock
mortality: a post hoc analysis of a multicenter trial. Crit Care
2009; 13 6:R181.
55. Zhang L, Zhu G, Han L, Fu P. Early goal-directed therapy in the management of severe sepsis
or septic shock
in adults: a meta-analysis of randomized controlled trials. BMC Med
56. Cherpanath TG, Smeding L, Lagrand WK, Hirsch A, Schultz MJ, Groeneveld JA. Pulse pressure variation does not reflect stroke volume variation in mechanically ventilated rats with lipopolysaccharide-induced pneumonia. Clin Exp Pharmacol Physiol
2014; 41 1:98–104.
57. Cecconi M, De BD, Antonelli M, Beale R, Bakker J, Hofer C, Jaeschke R, Mebazaa A, Pinsky MR, Teboul JL, et al. Consensus on circulatory shock and hemodynamic monitoring. Task force of the European Society of Intensive Care Medicine. Intensive Care Med
2014; 40 12:1795–1815.
58. Fencl V, Jabor A, Kazda A, Figge J. Diagnosis of metabolic acid-base disturbances in critically ill patients. Am J Respir Crit Care Med
2000; 162 6:2246–2251.
59. Kellum JA. Saline-induced hyperchloremic metabolic acidosis. Crit Care Med
2002; 30 1:259–261.
60. Stewart PA. Modern quantitative acid-base chemistry. Can J Physiol Pharmacol
1983; 61 12:1444–1461.
61. Morgan TJ, Venkatesh B, Beindorf A, Andrew I, Hall J. Acid-base and bio-energetics during balanced versus unbalanced normovolaemic haemodilution. Anaesth Intensive Care
2007; 35 2:173–179.
62. Caironi P, Langer T, Gattinoni L. Albumin in critically ill patients: the ideal colloid? Curr Opin Crit Care
2015; 21 4:302–308.
63. Wagner K, Georgieff M, Asfar P, Calzia E, Knoferl MW, Radermacher P. Of mice and men (and sheep, swine, etc.): the intriguing hemodynamic and metabolic effects of hydrogen sulfide (H2S). Crit Care
2011; 15 2:146.
64. Radermacher P, Haouzi P. A mouse is not a rat is not a man: species-specific metabolic responses to sepsis
—a nail in the coffin of murine models for critical care research? Intensive Care Med Exp
2013; 1 1:26.
65. Zolfaghari PS, Pinto BB, Dyson A, Singer M. The metabolic phenotype of rodent sepsis
: cause for concern? Intensive Care Med Exp
2013; 1 1:25.
66. Angus DC, van der Poll T. Severe sepsis
and septic shock
. N Engl J Med
2013; 369 21:2063.
67. Dellinger RP, Levy MM, Carlet JM, Bion J, Parker MM, Jaeschke R, Reinhart K, Angus DC, Brun-Buisson C, Beale R, et al. Surviving sepsis
campaign: international guidelines for management of severe sepsis
and septic shock
. Crit Care Med
2008; 36 1:296–327.
68. Rivers E, Nguyen B, Havstad S, Ressler J, Muzzin A, Knoblich B, Peterson E, Tomlanovich M. Early goal-directed therapy in the treatment of severe sepsis
and septic shock
. N Engl J Med
2001; 345 19:1368–1377.
69. Tisherman SA, Barie P, Bokhari F, Bonadies J, Daley B, Diebel L, Eachempati SR, Kurek S, Luchette F, Carlos PJ, et al. Clinical practice guideline: endpoints of resuscitation. J Trauma
2004; 57 4:898–912.
70. Semler MW, Rice TW. Sepsis
resuscitation: fluid choice and dose. Clin Chest Med
2016; 37 2:241–250.
71. Brandt S, Regueira T, Bracht H, Porta F, Djafarzadeh S, Takala J, Gorrasi J, Borotto E, Krejci V, Hiltebrand LB, et al. Effect of fluid resuscitation
on mortality and organ function in experimental sepsis
models. Crit Care
2009; 13 6:R186.
72. Wan L, Bellomo R, May CN. Bolus hypertonic or normal saline resuscitation in gram-negative sepsis
: systemic and regional haemodynamic effects in sheep. Crit Care Resusc
2011; 13 4:262–270.
73. Stenzel T, Weidgang C, Wagner K, Wagner F, Groger M, Weber S, Stahl B, Wachter U, Vogt J, Calzia E, et al. Association of kidney tissue barrier disrupture and renal dysfunction in resuscitated murine septic shock
2016; 46 4:398–404.
74. Singer M. Antibiotics for sepsis
: does each hour really count, or is it incestuous amplification? Am J Respir Crit Care Med
2017; 196 7:800–802.
75. Maybauer MO, Maybauer DM, Traber LD, Westphal M, Enkhbaatar P, Morita N, Jodoin JM, Heggers JP, Herndon DN, Traber DL. Gentamicin improves hemodynamics in ovine septic shock
after smoke inhalation injury. Shock
2005; 24 3:226–231.
76. Torres-Duenas D, Benjamim CF, Ferreira SH, Cunha FQ. Failure of neutrophil migration to infectious focus and cardiovascular changes on sepsis
in rats: effects of the inhibition of nitric oxide production, removal of infectious focus, and antimicrobial treatment. Shock
2006; 25 3:267–276.
77. Assfalg V, Huser N, Reim D, Kaiser-Moore S, Rossmann-Bloeck T, Weighardt H, Novotny AR, Stangl MJ, Holzmann B, Emmanuel KL. Combined immunosuppressive and antibiotic therapy improves bacterial clearance and survival of polymicrobial septic peritonitis. Shock
2010; 33 2:155–161.
78. Liu MS, Liu CH, Wu G, Zhou Y. Antisense inhibition of secretory and cytosolic phospholipase A2 reduces the mortality in rats with sepsis
*. Crit Care Med
2012; 40 7:2132–2140.
79. Maybauer MO, Maybauer DM, Fraser JF, Westphal M, Szabo C, Cox RA, Hawkins HK, Traber LD, Traber DL. Combined recombinant human activated protein C and ceftazidime prevent the onset of acute respiratory distress syndrome in severe sepsis
2012; 37 2:170–176.
80. Opal SM, Ellis JL, Suri V, Freudenberg JM, Vlasuk GP, Li Y, Chahin AB, Palardy JE, Parejo N, Yamamoto M, et al. Pharmacological SIRT1 activation improves mortality and markedly alters transcriptional profiles that accompany experimental sepsis
2016; 45 4:411–418.
81. Turnbull IR, Wlzorek JJ, Osborne D, Hotchkiss RS, Coopersmith CM, Buchman TG. Effects of age on mortality and antibiotic efficacy in cecal ligation and puncture. Shock
2003; 19 4:310–313.
82. Peng ZY, Wang HZ, Srisawat N, Wen X, Rimmele T, Bishop J, Singbartl K, Murugan R, Kellum JA. Bactericidal antibiotics temporarily increase inflammation and worsen acute kidney injury in experimental sepsis
. Crit Care Med
2012; 40 2:538–543.
83. Iskander KN, Vaickus M, Duffy ER, Remick DG. Shorter duration of post-operative antibiotics for cecal ligation and puncture does not increase inflammation or mortality. PLoS One
2016; 11 9:e0163005.
84. Smith SE, Rumbaugh KA, May AK. Evaluation of a short course of antimicrobial therapy
for complicated intra-abdominal infections in critically ill surgical patients. Surg Infect (Larchmt)
2017; 18 6:742–750.
85. Tsai D, Lipman J, Roberts JA. Pharmacokinetic/pharmacodynamic considerations for the optimization of antimicrobial delivery in the critically ill. Curr Opin Crit Care
2015; 21 5:412–420.
86. D’Avolio A, Pensi D, Baietto L, Pacini G, Di PG, De Rosa FG. Daptomycin pharmacokinetics and pharmacodynamics in septic and critically ill patients. Drugs
2016; 76 12:1161–1174.
87. Hauser WE Jr, Remington JS. Effect of antibiotics on the immune response. Am J Med
1982; 72 5:711–716.
88. Ziegeler S, Raddatz A, Hoff G, Buchinger H, Bauer I, Stockhausen A, Sasse H, Sandmann I, Horsch S, Rensing H. Antibiotics modulate the stimulated cytokine response to endotoxin in a human ex vivo, in vitro model. Acta Anaesthesiol Scand
2006; 50 9:1103–1110.
89. Iapichino G, Callegari ML, Marzorati S, Cigada M, Corbella D, Ferrari S, Morelli L. Impact of antibiotics on the gut microbiota of critically ill patients. J Med Microbiol
2008; 57 (Pt 8):1007–1014.
90. Kalghatgi S, Spina CS, Costello JC, Liesa M, Morones-Ramirez JR, Slomovic S, Molina A, Shirihai OS, Collins JJ. Bactericidal antibiotics induce mitochondrial dysfunction and oxidative damage in Mammalian cells. Sci Transl Med
2013; 5 192:192ra85.
91. Singh R, Sripada L, Singh R. Side effects of antibiotics during bacterial infection: mitochondria, the main target in host cell. Mitochondrion
92. Morgun A, Dzutsev A, Dong X, Greer RL, Sexton DJ, Ravel J, Schuster M, Hsiao W, Matzinger P, Shulzhenko N. Uncovering effects of antibiotics on the host and microbiota using transkingdom gene networks. Gut
2015; 64 11:1732–1743.
93. Sommer F, Anderson JM, Bharti R, Raes J, Rosenstiel P. The resilience of the intestinal microbiota influences health and disease. Nat Rev Microbiol
2017; 15 10:630–638.
94. Heine HS, Louie A, Adamovicz JJ, Amemiya K, Fast RL, Miller L, Opal SM, Palardy J, Parejo NA, Sorgel F, et al. Evaluation of imipenem for prophylaxis and therapy of Yersinia pestis delivered by aerosol in a mouse model of pneumonic plague. Antimicrob Agents Chemother
2014; 58 6:3276–3284.
95. Vianna RC, Gomes RN, Bozza FA, Amancio RT, Bozza PT, David CM, Castro-Faria-Neto HC. Antibiotic treatment in a murine model of sepsis
: impact on cytokines and endotoxin release. Shock
2004; 21 2:115–120.
96. Kumar A, Roberts D, Wood KE, Light B, Parrillo JE, Sharma S, Suppes R, Feinstein D, Zanotti S, Taiberg L, et al. Duration of hypotension before initiation of effective antimicrobial therapy
is the critical determinant of survival in human septic shock
. Crit Care Med
2006; 34 6:1589–1596.
97. Kumar A, Ellis P, Arabi Y, Roberts D, Light B, Parrillo JE, Dodek P, Wood G, Kumar A, Simon D, et al. Initiation of inappropriate antimicrobial therapy
results in a fivefold reduction of survival in human septic shock
2009; 136 5:1237–1248.
98. Paul M, Shani V, Muchtar E, Kariv G, Robenshtok E, Leibovici L. Systematic review and meta-analysis of the efficacy of appropriate empiric antibiotic therapy for sepsis
. Antimicrob Agents Chemother
2010; 54 11:4851–4863.
99. Sawyer RG, Adams RB, Pruett TL. Aztreonam vs. gentamicin in experimental peritonitis and intra-abdominal abscess formation. Am Surg
1994; 60 11:849–853.
100. Andrews JM. Determination of minimum inhibitory concentrations. J Antimicrob Chemother
2001; 48 (Suppl.):15–16.
101. Kita Y, Yamazaki T, Imada A. Comparative pharmacokinetics of SCE-2787 and related antibiotics in experimental animals. Antimicrob Agents Chemother
1992; 36 11:2481–2486.
102. Hayakawa H, Fukushima Y, Kato H, Fukumoto H, Kadota T, Yamamoto H, Kuroiwa H, Nishigaki J, Tsuji A. Metabolism and disposition of novel des-fluoro quinolone garenoxacin in experimental animals and an interspecies scaling of pharmacokinetic parameters. Drug Metab Dispos
2003; 31 11:1409–1418.
103. Siefert HM, Domdey-Bette A, Henninger K, Hucke F, Kohlsdorfer C, Stass HH. Pharmacokinetics of the 8-methoxyquinolone, moxifloxacin: a comparison in humans and other mammalian species. J Antimicrob Chemother
1999; 43 (Suppl B):69–76.
104. Marik PE. Aminoglycoside volume of distribution and illness severity in critically ill septic patients. Anaesth Intensive Care
1993; 21 2:172–173.
105. Baptista JP, Sousa E, Martins PJ, Pimentel JM. Augmented renal clearance in septic patients and implications for vancomycin optimisation. Int J Antimicrob Agents
2012; 39 5:420–423.
106. Macedo RS, Onita JH, Wille MP, Furtado GH. Pharmacokinetics and pharmacodynamics of antimicrobial drugs in intensive care unit patients. Shock
2013; 39 (Suppl.):124–128.
107. Jung B, Mahul M, Breilh D, Legeron R, Signe J, Jean-Pierre H, Uhlemann AC, Molinari N, Jaber S. Repeated Piperacillin-Tazobactam plasma concentration measurements in severely obese versus nonobese critically ill septic patients and the risk of under- and overdosing. Crit Care Med
2017; 45 5:e470–e478.
108. Hobbs AL, Shea KM, Roberts KM, Daley MJ. Implications of augmented renal clearance on drug dosing in critically ill patients: a focus on antibiotics. Pharmacotherapy
2015; 35 11:1063–1075.
109. Somani P, Freimer EH, Gross ML, Higgins JT Jr. Pharmacokinetics of imipenem-cilastatin in patients with renal insufficiency undergoing continuous ambulatory peritoneal dialysis. Antimicrob Agents Chemother
1988; 32 4:530–534.
110. Tajima N, Nagashima S, Uematsu T, Torii H, Tajima M, Hishida A, Naganuma H. Prediction of pharmacokinetics of antibiotics in patients with end-stage renal disease. Biol Pharm Bull
2006; 29 7:1454–1459.
111. Nicolau DP. Pharmacokinetic and pharmacodynamic properties of meropenem. Clin Infect Dis
2008; 47 (Suppl 1):S32–S40.
112. Couffignal C, Pajot O, Laouenan C, Burdet C, Foucrier A, Wolff M, Armand-Lefevre L, Mentre F, Massias L. Population pharmacokinetics of imipenem in critically ill patients with suspected ventilator-associated pneumonia and evaluation of dosage regimens. Br J Clin Pharmacol
2014; 78 5:1022–1034.
113. Sakka SG, Glauner AK, Bulitta JB, Kinzig-Schippers M, Pfister W, Drusano GL, Sorgel F. Population pharmacokinetics and pharmacodynamics of continuous versus short-term infusion of imipenem-cilastatin in critically ill patients in a randomized, controlled trial. Antimicrob Agents Chemother
2007; 51 9:3304–3310.
114. Roberts JA, Ulldemolins M, Roberts MS, McWhinney B, Ungerer J, Paterson DL, Lipman J. Therapeutic drug monitoring of beta-lactams in critically ill patients: proof of concept. Int J Antimicrob Agents
2010; 36 4:332–339.
115. Dulhunty JM, Roberts JA, Davis JS, Webb SA, Bellomo R, Gomersall C, Shirwadkar C, Eastwood GM, Myburgh J, Paterson DL, et al. A protocol for a multicentre randomised controlled trial of continuous beta-lactam infusion compared with intermittent beta-lactam dosing in critically ill patients with severe sepsis
: the BLING II study. Crit Care Resusc
2013; 15 3:179–185.
116. Inoue S, Suzuki-Utsunomiya K, Okada Y, Taira T, Iida Y, Miura N, Tsuji T, Yamagiwa T, Morita S, Chiba T, et al. Reduction of immunocompetent T cells followed by prolonged lymphopenia in severe sepsis
in the elderly. Crit Care Med
2013; 41 3:810–819.
117. Inoue S, Suzuki K, Komori Y, Morishita Y, Suzuki-Utsunomiya K, Hozumi K, Inokuchi S, Sato T. Persistent inflammation and T cell exhaustion in severe sepsis
in the elderly. Crit Care
2014; 18 3:R130.
118. Fox AC, Robertson CM, Belt B, Clark AT, Chang KC, Leathersich AM, Dominguez JA, Perrone EE, Dunne WM, Hotchkiss RS, et al. Cancer causes increased mortality and is associated with altered apoptosis in murine sepsis
. Crit Care Med
2010; 38 3:886–893.
119. Banerjee D, Opal SM. Age, exercise, and the outcome of sepsis
. Crit Care
2017; 21 1:286.
120. Angele MK, Frantz MC, Chaudry IH. Gender and sex hormones influence the response to trauma and sepsis
: potential therapeutic approaches. Clinics (Sao Paulo)
2006; 61 5:479–488.
121. Sterling SA, Miller WR, Pryor J, Puskarich MA, Jones AE. The impact of timing of antibiotics on outcomes in severe sepsis
and septic shock
: a systematic review and meta-analysis. Crit Care Med
2015; 43 9:1907–1915.
122. Lewis AJ, Griepentrog JE, Zhang X, Angus DC, Seymour CW, Rosengart MR. Prompt administration of antibiotics and fluids in the treatment of sepsis
: a murine trial. Crit Care Med
2018; 46 5:e426–e434.