תוצאת חיפוש

Gentamycin Distribution Volume in a Mechanically Ventilated Patient

H. Seligmann, S. Nicola, S.H. Krimerman

Clinical Pharmacology and Intensive Care Units, Bnai-Zion Medical Center and Bruce Rappaport Faculty of Medicine, The Technion, Haifa

Mechanical ventilation (MV) of more than 32 hours may alter the gentamycin pharmacokinetic profile by increasing its volume of distribution (VD). As a result, the standard garamycin dosage regime has to be adjusted in order to obtain an adequate peak serum concentration, which is well correlated with the efficacy of garamycin therapy. Garamycin is a water- soluble drug with negligible binding to plasma albumin, so its VD approximates the volume of extra-cellular fluid, which may be expanded by MV. MV-related fluid retention is mediated via various homeostatic compensatory systems. They are activated to combat the decrease in cardiac output and central blood volume caused by MV, due to the increase in airway and intrathoracic pressure. These phenomena are more prominent during prolonged ventilation, PEEP or C-PAP ventilation, and in previously hypovolemic patients. Patients requiring MV for more than 32 hours had an average garamycin VD of 0.36 L/Kg compared with the mean VD of 0.25 L/Kg in normal adults. In the patient presented, a similar change in garamycin VD was seen, while conventional doses given during MV failed to reach suitable clinical peak levels.

Brain Imaging and its Clinical Application in Psychiatry

Talma Hendler, Raz Gross, Elinor Goshen, Meir Faibel, Shmuel Hirshmann, Tzila S. Zwass, Leon Grunhaus, Joseph Zohar

Psychiatry Unit, Nuclear Medicine Institute and Diagnostic Radiology Dept., Chaim Sheba Medical Center, Tel Hashomer and Sackler Faculty of Medicine, Tel Aviv University

The common structural and functional brain imaging techniques are described from a practical, clinical point of view. The clinical indications for brain imaging in psychiatry are reviewed in relation to the specific limitations and advantages of each technique. The clinical applications of computerized tomography (CT), magnetic resonance imaging (MRI) and single photon emission computerized tomography (SPECT) are discussed in relation to the differential diagnosis between organic and functional psychiatric disorders. In a 55-year-old man with late onset of behavioral changes but without neurological signs the application of structural brain imaging (CT and MRI) in case management was demonstrated. The imaging findings involved the differential diagnosis between depression and focal brain lesions. In a 38-year-old man with personality changes and depression following a traumatic brain injury, time interval repeated functional brain imaging (SPECT) was used. Brain imaging reflected improvement in clinical status following treatment and was able to differentiate between reversible and permanent traumatic brain injuries. The superior yield of time interval repeated functional imaging in diagnosis and management of postconcussion syndrome is discussed.

Macroenzymes: an Interesting Laboratory Finding, without Clinical Relevance

C. Perry, H. Peretz, E. Graf, O. Ben-Tal, A. Eldor

Hematology Dept. and Biochemistry Laboratory, Tel Aviv-Sourasky Medical Center, and Sackler Faculty of Medicine, Tel Aviv University

Macroenzymes are complexes of serum enzymes with proteins which have a higher molecular weight and longer plasma half-life than the normal enzyme. The presence of macroenzymes is suggested by finding increased serum enzyme activity, not associated with symptoms. Thus, macroenzymes can cause diagnostic errors and the performance of unnecessary tests or invasive procedures. We describe 2 patients with highly elevated serum levels of lactate dehydrogenase (LDH) and creatine kinase (CK) due to formation of complexes with immunoglobulin G. 1 patient had LDH of 4500 u/L but was otherwise normal and in the second CK was elevated with no evidence of ischemic heart disease. Awareness of the phenomenon of macroenzymes may save the patient long and sometimes invasive investigation.