Optimized Antibiotic Therapy in Patients With Subarachnoid Haemorrhage (ES) and Cerebral Haemorrhage (EC)

Haemorrhagic stroke is a devastating disease with a high rate of disability and mortality. In addition to the direct effects of the haemorrhagic event and to the secondary neurological complications, patients with haemorrhagic strokes are predisposed to medical complications that can have a direct impact on both clinical outcome and treatment costs. It has been estimated that between 79% and 100% of patients with subarachnoid haemorrhage (ES) and cerebral haemorrhage (EC) have at least one of these complications. Among them, the most common are infections, seizures, hyponatremia, hypomagnesemia, hypokalemia and venous thromboembolism.

A possible reason that can be responsible for such a high frequency of complications, especially infectious, can be identified in a pathophysiological alteration of the circulatory and renal haemodynamics of this population. Specifically, these patients frequently have a hyperdynamic state which results in a high renal clearance (CrCl) (augmented renal clearance - ARC, defined as a measured CrCl ≥ 130 ml/min/1.73m2). In this regard, a recent prospective observational clinical study conducted in an intensive care unit of a third level US university hospital showed that 94% of patients with ES and 50% of those with EC had an ARC for a duration of at least one day during the hospital stay.

In consideration of the fact that the ARC has been historically underestimated and that an accurate assessment of renal function through the measured CrCl is not regularly carried out on all patients even if they are critical, the main risk from the point of view of therapeutic appropriateness is that of not adjust the dosing regimen of drugs eliminated through the kidney in relation to the presence and extent of the ARC. Moreover, the clinician often ignores the time course of the ARC as well as the modalities with which to carry out the dosage adjustment. This could lead to sub-therapeutic concentrations for renally excreted drugs, as typically are water-soluble antibiotics such as beta-lactams, aminoglycosides, daptomycin, linezolid, antifungal fluconazole and antivirals ganciclovir and aciclovir, resulting in an increase in the risk of therapeutic failure.

Although there is currently a great deal of evidence describing ARC in various subgroups of critically ill patients, on the other hand there is little documentation regarding the effect that ARC can have on exposure to renally eliminated drugs.

Therefore, the aim of this study is to prospectively evaluate the proportion of plasma under-exposure to hydrophilic antimicrobials in patients with ES or EC and with ARC, in order to verify whether the recommended dosage regimens for these drugs are adequate for reaching the pharmacodynamic targets of therapeutic efficacy.