Bacteria Detected and the Pharmacokinetics of Antibiotics During Brain Hypothermia

We examined the state of bacteria detected from patients during brain hypothermia and the pharmacokinetics of antibiotics administered for antibiotic prophylaxis. Samples including blood were collected from patients who underwent brain hypothermia at the Nihon University Itabashi Hospital Emergency and Critical Care Center, and the type of bacteria and interval until detection were investigated using these samples. Simultaneously, we measured concentrations of antibiotics administered for antibiotic prophylaxis [cefmetazole (CMZ), flomoxef (FMOX), cefoperazone/sulbactam (CPZ/SBT), aspoxicillin (ASPC), arbekacin (ABK), amikacin (AMK)] and compared the half-lives of these agents during the cooling stage or during the cooling and rewarming stages. Bacteria such as methicillin-resistant staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Candida were mainly detected. The mean interval until the bacterial detection was 4.4 days after rewarming was started. Of the administered antibiotics, half-lives of agents that are mainly eliminated via kidney excretion (CMZ, FMOX, SBT, ABK) did not differ during the cooling and rewarming stages. However, for two patients receiving CPZ, an agent metabolized in the liver, the half-life of CPZ was markedly prolonged during hypothermia in one patient with liver dysfunction, whereas there was no prolongation in the other patient. The results of this study suggest that the types of bacteria detected are similar to those in other patients hospitalized in the intensive care unit. With respect to the pharmacokinetics of antibiotics, the half-life of CPZ was prolonged in one patient during the cooling stage, suggesting that the drug-metabolizing capacity in the liver parenchyma may be reduced during hypothermia. Therefore, antibiotics that are metabolized in the liver should be administered cautiously.