Power injector

II.f.1.3. Insulin delivery. Traditionally insulin was given intramuscularly and later subcutaneously. New technology has provided devices for insulin administrations including pen-devices, air powered injectors, external insulin infusion pumps (or continuous subcutaneous insulin infusion, CSII), and implantable insulin infusion pumps. Some novel forms of insulin delivery have been introduced, for example intranasal insulin gives peak insulin concentrations at 10-20 minutes after administration, but most insulin is still administered subcutaneously. 

For contrast agent injection an MR compatible power injector should be used to ensure a high and reproducible injection rate. Injection rate should be at least 3 ml/s. Injection should be started parallel to the dynamic scan. This ensures a sufficient number of measurements for calculation of the pre-contrast baseline and guarantees that the whole first pass is comprised, if the scans are repeated for at least 1 min. 

Saline chaser Less contrast medium Decreased streak artifact at origin of great vessels Greater absolute difference in attenuation Requires potentially expensive specialized dual head CT power injectors... 

Multiphasic injection (Fleischmann) Uniform plateau of enhancement Accounts for varying patient physiology Requires test bolus Requires dual phase CT power injector... 

Multiphasic, with exponential decay (Bae) Uniform plateau of enhancement Requires multiple assumptions regarding patient factors that may not be known or justifiable Requires CT power injector capable of exponential decay mode... 

Hopper KD et al (1997) Thoracic spiral CT delivery of contrast material pushed with injectable saline solution in a power injector. Radiology 205(1) 269-271. 

Haage P et al (2000) Reduction of contrast material dose and artifacts by a saline flush using a double power injector in helical CT of the thorax. AJR Am J Roentgenol 174(4) 1049. 

Contrast Administration. The cine acquisition of CTP forms the final step in the acute stroke imaging evaluation. With dynamic, quantitative CTP, an additional contrast bolus of 35 5 mL is administered via power injector (at a rate of 7 mL/s), with a saline chaser of 20 0 mL at the same injection rate. The contrast used should be of high concentration, typically 350-370 g/dL of iodine, for optimal signal-to-noise ratio for perfusion maps calculation. 

In stable and cooperative patients, the diagnostic arteriography is performed under local anesthesia via a transfemoral access and in the classical Seldinger technique. Celiac trunk and the superior mesenteric artery (SMA) are catheterized with preshaped single-use 4- or 5-F catheters of the Cobra or side-winder type. lodinated nonionic iso-osmolar contrast medium (25-35 ml at a rate of 4-6 ml/s) is injected by a power injector into the celiac trunk and SMA. In patients with renal insufficiency, contrast allergy or hyperthyroidism gadolinium chelates (MRI contrast medium) have been suggested as a substitute for iodinated contrast medium [53], but reports on its use in the visceral arteries are still awaited. 

Generally speaking, a moderate to high iodine delivery rate (IDR) is needed for CTA of the chest. Therefore, 1.5-2.0 g iodine/s should be administered intravenously. The contrast medium delivery has to be maintained for a longer time, as an opacification of the pulmonary circulation and the systemic circulation is needed at the same time. Dual-head power injectors, individual adaptation of the contrast delivery... 

If iomeprol is used at an iodine concentration of 400mg/ml, then the power injector should allow keeping the contrast agent at body temperature. With the patient lying in final position with elevated arms above the... 

A safe IV line is always necessary, and our preference goes to an antecubital catheter. The largest possible size is chosen. Placement of the catheter is ideally performed by a nurse in the outpatient suite after skin preparation with anesthetic cream (lidocaine-prilocaine, Emla ). This catheter makes it possible to use a power injector. Power injection provides an excellent examination quality, and continuous flow decreases the risk of extra vascular passage. The injection should be visually monitored and stopped in case of extra-vascular passage. In younger children, hand injection under visual control seems safer. 

CT examination includes the acquisition of non-enhanced and enhanced images the latter are performed during the arterial, portal and delayed hepatic phases, with a start delay of 25-35 s, 60-70 s and 5-10 min, respectively, after the intravenous bolus injection of iodinated contrast material. High concentration contrast medium (370-400 mgl/ml), administered with a flow rate of 4-5 ml/s by means of a power injector, is usually preferred. 

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