Medikamentendosierung unter extrakorporaler Therapie

Excessive unbound cefazolin concentrations in critically ill patients receiving veno-arterial extracorporeal membrane oxygenation (vaECMO): an observational study

The scope of extracorporeal membrane oxygenation (ECMO) is expanding, nevertheless, pharmacokinetics in patients receiving cardiorespiratory support are fairly unknown leading to unpredictable drug concentrations. Currently, there are no clear guidelines for antibiotic dosing during ECMO. This study aims to evaluate the pharmacokinetics (PK) of cefazolin in patients undergoing ECMO treatment. Total and unbound plasma cefazolin concentration of critically ill patients on veno-arterial ECMO were determined. Observed PK was compared to dose recommendations calculated by an online available, free dosing software. Concentration of cefazolin varied broadly despite same dosage in all patients. The mean total and unbound plasma concentration were high showing significantly (p = 5.8913 E−09) greater unbound fraction compared to a standard patient. Cefazolin clearance was significantly (p = 0.009) higher in patients with preserved renal function compared with CRRT. Based upon the calculated clearance, the use of dosing software would have led to lower but still sufficient concentrations of cefazolin in general. Our study shows that a “one size fits all” dosing regimen leads to excessive unbound cefazolin concentration in these patients. They exhibit high PK variability and decreased cefazolin clearance on ECMO appears to compensate for ECMO- and critical illness-related increases in volume of distribution.

[Hot rods in the ICU : What is the antibiotic mileage of your renal replacement therapy?]

We would neither be disappointed nor upset if the gas mileage on the sticker of a car didn't match our personal, real-life fuel consumption. Depending on our daily route to work, our style of accelerating and the number of passengers in our carpool, the gas mileage will vary. As soon as the falcon wing door of our car is closed and entrance to the ICU is granted, we tend to forget all of this, even though another hot rod is waiting there for us. Renal replacement therapy is like a car; it fulfills goals, such as the removal of uremic toxins and accumulated fluids, but it also "consumes" (removes) antibiotics. Unlike catecholamines, where we have the mean arterial pressure on our ICU dashboard, we do not have a gauge to measure antibiotic "consumption", i.e. elimination by renal replacement therapy. This manuscript describes the principles and basic knowledge to improve dosing of antibiotics in critically ill patients undergoing renal replacement therapy. As in modern cars, we briefly touch on hybrid therapies combining renal replacement therapy with extracorporeal lung support or adsorbent technologies that remove cytokines or bacteria. Further, the importance of considering body size and body composition is addressed, especially for choosing the right initial dose of antibiotics. Lastly we point out the dire need to increase the availability of timely and affordable therapeutic drug monitoring on the most commonly used antiinfectives, ideally using point-of-care devices at the bedside.

[Successful hemodialysis for life-threatening carbamazepine drug overdose: Case-based introduction of new guidelines]

BACKGROUND

Over the last decade, there has been a paradigm shift in the extracorporeal treatment of intoxications. The availability of new treatment options, especially new membranes has led to a decrease in the use of techniques like charcoal hemoperfusion, once considered the gold standard to eliminate highly protein bound substances.

EXTRIP GUIDELINES

The EXtracorporeal Treatments In Poisoning (EXTRIP) workgroup is a collaborative international effort of pharmacologists, toxicologists, critical care physicians, and nephrologists that is reviewing all available evidence in extracorporeal procedures for the treatment of poisonings in a standardized way to distill treatment recommendations for the physician at the bedside. One of the first available EXTRIP guidelines summarizes treatment recommendations for severe carbamazepine intoxications.

CASE REPORT

We report the case of a 43-year-old Caucasian woman with who ingested about 21 g carbamazepine in a suicidal attempt together with alcohol. Combining gastroscopic removal of carbamazepine and multiple dose activated charcoal with intermittent high-flux hemodialysis lowered the initial carbamazepine level of 56.5 mg/l (47 mg/l before dialysis) to 25 mg/l. The patient, who initially required mechanical ventilation could be transferred to the psychiatric ward 24 h after ICU admission.