Critically ill patients are at high risk for development of life-threatening infection leading to sepsis and multiple organ failure. Adequate antimicrobial therapy is pivotal for optimizing the ...chances of survival. However, efficient dosing is problematic because pathophysiological changes associated with critical illness impact on pharmacokinetics of mainly hydrophilic antimicrobials. Concentrations of hydrophilic antimicrobials may be increased because of decreased renal clearance due to acute kidney injury. Alternatively, antimicrobial concentrations may be decreased because of increased volume of distribution and augmented renal clearance provoked by systemic inflammatory response syndrome, capillary leak, decreased protein binding and administration of intravenous fluids and inotropes. Often multiple conditions that may influence pharmacokinetics are present at the same time thereby excessively complicating the prediction of adequate concentrations. In general, conditions leading to underdosing are predominant. Yet, since prediction of serum concentrations remains difficult, therapeutic drug monitoring for individual fine-tuning of antimicrobial therapy seems the way forward.
Display omitted
OBJECTIVE:To discuss the altered pharmacokinetic properties of selected antibiotics in critically ill patients and to develop basic dose adjustment principles for this patient population.
DATA ...SOURCES:PubMed, EMBASE, and the Cochrane-Controlled Trial Register.
STUDY SELECTION:Relevant papers that reported pharmacokinetics of selected antibiotic classes in critically ill patients and antibiotic pharmacodynamic properties were reviewed. Antibiotics and/or antibiotic classes reviewed included aminoglycosides, β-lactams (including carbapenems), glycopeptides, fluoroquinolones, tigecycline, linezolid, lincosamides, and colistin.
DATA SYNTHESIS:Antibiotics can be broadly categorized according to their solubility characteristics which can, in turn, help describe possible altered pharmacokinetics that can be caused by the pathophysiological changes common to critical illness. Hydrophilic antibiotics (e.g., aminoglycosides, β-lactams, glycopeptides, and colistin) are mostly affected with the pathphysiological changes observed in critically ill patients with increased volumes of distribution and altered drug clearance (related to changes in creatinine clearance). Lipophilic antibiotics (e.g., fluoroquinolones, macrolides, tigecycline, and lincosamides) have lesser volume of distribution alterations, but may develop altered drug clearances. Using antibiotic pharmacodynamic bacterial kill characteristics, altered dosing regimens can be devised that also account for such pharmacokinetic changes.
CONCLUSIONS:Knowledge of antibiotic pharmacodynamic properties and the potential altered antibiotic pharmacokinetics in critically ill patients can allow the intensivist to develop individualized dosing regimens. Specifically, for renally cleared drugs, measured creatinine clearance can be used to drive many dose adjustments. Maximizing clinical outcomes and minimizing antibiotic resistance using individualized doses may be best achieved with therapeutic drug monitoring.
Ventriculostomy insertion is a common neurosurgical intervention and can be complicated by ventriculostomy-associated cerebrospinal fluid infection (VAI) which is associated with increased morbidity ...and mortality. This meta-analysis was aimed at determining the pooled incidence rate (number per 1000 catheter-days) of VAI.
Relevant studies were identified from MEDLINE and EMBASE and from reference searching of included studies and recent review articles on relevant topics. The Newcastle-Ottawa Scale was used to assess quality and risk of bias. A random effects model was used to pool individual study estimates and 95% confidence intervals (CI) were calculated using the exact Poisson method. Heterogeneity was assessed using the heterogeneity χ2 and I-squared tests. Subgroup analyses were performed and a funnel plot constructed to assess publication bias.
There were a total of 35 studies which yielded 752 infections from 66,706 catheter-days of observation. The overall pooled incidence rate of VAI was 11.4 per 1000 catheter days (95% CI 9.3 to 13.5), for high quality studies the rate was 10.6 (95% CI 8.3 to 13) and 13.5 (95% CI 8.9 to 18.1) for low quality studies. Studies which had mean duration of EVD treatment of less than 7 days had a pooled VAI rate of 19.6 per 1000 catheter-days, those with mean duration of 7-10 days had VAI rate of 12.8 per 1000 catheter-days and those with mean duration greater than 10 days had VAI rate of 8 per 1000 catheter-days. There was significant heterogeneity for the primary outcome (p = 0.004, I-squared = 44%) and most subgroups. The funnel plot did not show evidence for publication bias.
The incidence rate of VAI is 11.4 per 1000 catheter-days. Further research should focus on analysis of risk factors for VAI and techniques for reducing the rate of VAI.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Objective
There is little prospective data to guide effective dosing for antibiotic prophylaxis during surgery requiring cardiopulmonary bypass (CPB). We aim to describe the effects of CPB on the ...population pharmacokinetics (PK) of total and unbound concentrations of cefazolin and to recommend optimised dosing regimens.
Methods
Patients undergoing CPB for elective cardiac valve replacement were included using convenience sampling. Intravenous cefazolin (2g) was administered pre-incision and re-dosed at 4 hours. Serial blood and urine samples were collected and analysed using validated chromatography. Population PK modelling and Monte-Carlo simulations were performed using Pmetrics
®
to determine the fractional target attainment (FTA) of achieving unbound concentrations exceeding pre-defined exposures against organisms known to cause surgical site infections for 100% of surgery (100%
f
T
>MIC
).
Results
From the 16 included patients, 195 total and 64 unbound concentrations of cefazolin were obtained. A three-compartment linear population PK model best described the data. We observed that cefazolin 2g 4-hourly was insufficient to achieve the FTA of 100%
f
T
>MIC
for
Staphylococcus aureus
and
Escherichia coli
at serum creatinine concentrations ≤ 50 μmol/L and for
Staphylococcus epidermidis
at any of our simulated doses and serum creatinine concentrations. A dose of cefazolin 3g 4-hourly demonstrated >93% FTA for
S
.
aureus
and
E
.
coli
.
Conclusions
We found that cefazolin 2g 4-hourly was not able to maintain concentrations above the MIC for relevant pathogens in patients with low serum creatinine concentrations undergoing cardiac surgery with CPB. The simulations showed that optimised dosing is more likely with an increased dose and/or dosing frequency.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In a study of fluid resuscitation, patients received 6% hydroxyethyl starch (HES; 130/0.4) or saline until ICU discharge or death or for 90 days. There was no significant difference in 90-day ...mortality, although more patients in the HES group received renal-replacement therapy.
The administration of intravenous fluids to increase intravascular volume is a frequent intervention in the intensive care unit (ICU), but the choice of resuscitation fluid remains controversial.
1
,
2
Globally, 0.9% sodium chloride (saline) is the most commonly used fluid, although colloids are administered as often as crystalloids, and hydroxyethyl starch (HES) is the most frequently used colloid.
3
Several studies have questioned the safety of HES in critically ill patients, with particular concern that its use increases the risk of acute kidney injury.
4
,
5
Most concern has focused on the use of concentrated HES solutions (10%) with a molecular weight of . . .
Initial antimicrobial management of sepsis Niederman, Michael S; Baron, Rebecca M; Bouadma, Lila ...
Critical care (London, England),
08/2021, Letnik:
25, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Sepsis is a common consequence of infection, associated with a mortality rate > 25%. Although community-acquired sepsis is more common, hospital-acquired infection is more lethal. The most common ...site of infection is the lung, followed by abdominal infection, catheter-associated blood steam infection and urinary tract infection. Gram-negative sepsis is more common than gram-positive infection, but sepsis can also be due to fungal and viral pathogens. To reduce mortality, it is necessary to give immediate, empiric, broad-spectrum therapy to those with severe sepsis and/or shock, but this approach can drive antimicrobial overuse and resistance and should be accompanied by a commitment to de-escalation and antimicrobial stewardship. Biomarkers such a procalcitonin can provide decision support for antibiotic use, and may identify patients with a low likelihood of infection, and in some settings, can guide duration of antibiotic therapy. Sepsis can involve drug-resistant pathogens, and this often necessitates consideration of newer antimicrobial agents.
There is a need to better define the epidemiology of sepsis in intensive care units (ICUs) around the globe.
The Intensive Care over Nations (ICON) audit prospectively collected data on all adult ...(>16 years) patients admitted to the ICU between May 8 and May 18, 2012, except those admitted for less than 24 hours for routine postoperative surveillance. Data were collected daily for a maximum of 28 days in the ICU, and patients were followed up for outcome data until death, hospital discharge, or for 60 days. Participation was entirely voluntary.
The audit included 10069 patients from Europe (54.1%), Asia (19.2%), America (17.1%), and other continents (9.6%). Sepsis, defined as infection with associated organ failure, was identified during the ICU stay in 2973 (29.5%) patients, including in 1808 (18.0%) already at ICU admission. Occurrence rates of sepsis varied from 13.6% to 39.3% in the different regions. Overall ICU and hospital mortality rates were 25.8% and 35.3%, respectively, in patients with sepsis, but it varied from 11.9% and 19.3% (Oceania) to 39.5% and 47.2% (Africa), respectively. After adjustment for possible confounders in a multilevel analysis, independent risk factors for in-hospital death included older age, higher simplified acute physiology II score, comorbid cancer, chronic heart failure (New York Heart Association Classification III/IV), cirrhosis, use of mechanical ventilation or renal replacement therapy, and infection with
spp.
Sepsis remains a major health problem in ICU patients worldwide and is associated with high mortality rates. However, there is wide variability in the sepsis rate and outcomes in ICU patients around the globe.
Summary Infections in critically ill patients are associated with persistently poor clinical outcomes. These patients have severely altered and variable antibiotic pharmacokinetics and are infected ...by less susceptible pathogens. Antibiotic dosing that does not account for these features is likely to result in suboptimum outcomes. In this Review, we explore the challenges related to patients and pathogens that contribute to inadequate antibiotic dosing and discuss how to implement a process for individualised antibiotic therapy that increases the accuracy of dosing and optimises care for critically ill patients. To improve antibiotic dosing, any physiological changes in patients that could alter antibiotic concentrations should first be established; such changes include altered fluid status, changes in serum albumin concentrations and renal and hepatic function, and microvascular failure. Second, antibiotic susceptibility of pathogens should be confirmed with microbiological techniques. Data for bacterial susceptibility could then be combined with measured data for antibiotic concentrations (when available) in clinical dosing software, which uses pharmacokinetic/pharmacodynamic derived models from critically ill patients to predict accurately the dosing needs for individual patients. Individualisation of dosing could optimise antibiotic exposure and maximise effectiveness.
Low serum albumin levels are very common in critically ill patients, with reported incidences as high as 40-50%. This condition appears to be associated with alterations in the degree of protein ...binding of many highly protein-bound antibacterials, which lead to altered pharmacokinetics and pharmacodynamics, although this topic is infrequently considered in daily clinical practice. The effects of hypoalbuminaemia on pharmacokinetics are driven by the decrease in the extent of antibacterial bound to albumin, which increases the unbound fraction of the drug. Unlike the fraction bound to plasma proteins, the unbound fraction is the only fraction available for distribution and clearance from the plasma (central compartment). Hence, hypoalbuminaemia is likely to increase the apparent total volume of distribution (V(d)) and clearance (CL) of a drug, which would translate to lower antibacterial exposures that might compromise the attainment of pharmacodynamic targets, especially for time-dependent antibacterials. The effect of hypoalbuminaemia on unbound concentrations is also likely to have an important impact on pharmacodynamics, but there is very little information available on this area. The objectives of this review were to identify the original research papers that report variations in the highly protein-bound antibacterial pharmacokinetics (mainly V(d) and CL) in critically ill patients with hypoalbuminaemia and without renal failure, and subsequently to interpret the consequences for antibacterial dosing. All relevant articles that described the pharmacokinetics and/or pharmacodynamics of highly protein-bound antibacterials in critically ill patients with hypoalbuminaemia and conserved renal function were reviewed. We found that decreases in the protein binding of antibacterials in the presence of hypoalbuminaemia are frequently observed in critically ill patients. For example, the V(d) and CL of ceftriaxone (85-95% protein binding) in hypoalbuminaemic critically ill patients were increased 2-fold. A similar phenomenon was reported with ertapenem (85-95% protein binding), which led to failure to attain pharmacodynamic targets (40% time for which the concentration of unbound free antibacterial was maintained above the minimal inhibitory concentration fT>MIC of the bacteria throughout the dosing interval). The V(d) and CL of other highly protein-bound antibacterials such as teicoplanin, aztreonam, fusidic acid or daptomycin among others were significantly increased in critically ill patients with hypoalbuminaemia compared with healthy subjects. Increased antibacterial V(d) appeared to be the most significant pharmacokinetic effect of decreased albumin binding, together with increased CL. These pharmacokinetic changes may result in decreased achievement of pharmacodynamic targets especially for time-dependent antibacterials, resulting in sub-optimal treatment. The effects on concentration-dependent antibacterial pharmacodynamics are more controversial due to the lack of data on this topic. In conclusion, altered antibacterial-albumin binding in the presence of hypoalbuminaemia is likely to produce significant variations in the pharmacokinetics of many highly protein-bound antibacterials. Dose adjustments of these antibacterials in critically ill patients with hypoalbuminaemia should be regarded as another step for antibacterial dosing optimization. Moreover, some of the new antibacterials in development exhibit a high level of protein binding although hypoalbuminaemia is rarely considered in clinical trials in critically ill patients. Further research that defines dosing regimens that account for such altered pharmacokinetics is recommended.
PDF
