tailieunhanh - Ebook Handbook of drugs in intensive care - An A-Z guide (5th edition): Part 2

(BQ) The second section contains topics relevant to the critically ill patients, including factors that may affect drug prescribing and management of medical emergencies. There is also a key data section showing weight conversions, BMI and corresponding dosage calculations, and an invaluable chart indicating drug compatibility for IV administration. | Short Notes ROUTES OF ADMINISTRATION Intravenous This is the most common route employed in the critically ill. It is reliable having no problems of absorption avoids first-pass metabolism and has a rapid onset of action. Its disadvantages include the increased risk of serious side-effects and the possibility of phlebitis or tissue necrosis if extravasation occurs. Intramuscular The need for frequent painful injections the presence of a coagulopathy risk the development of a haematoma which may become infected and the lack of muscle bulk often seen in the critically ill means that this route is seldom used in the critically ill. Furthermore variable absorption because of changes in cardiac output and blood flow to muscles posture and site of injection makes absorption unpredictable. Subcutaneous Rarely used except for low molecular weight heparin when used for prophylaxis against DVT. Absorption is variable and unreliable. Oral In the critically ill this route includes administrations via NG NJ PEG PEJ or surgical jejunostomy feeding tubes. Medications given via these enteral feeding tubes should be liquid or finely crushed dissolved in water. Rinsing should take place before and after feed or medication has been administered using 20 30 ml WFI. In the seriously ill patient this route is not commonly used to give drugs. Note than some liquid preparations contain sorbitol which has a laxative effect at daily doses 15 g. An example of this is baclofen where the Lioresal liquid preparation contains g 5 ml of sorbitol so a dose of 20 mg 6 hourly would deliver 44 g of sorbitol. In these cases it is preferable to crush tablets than to administer liquid preparations. The effect of pain and its treatment with opioids variations in splanchnic blood flow and changes in intestinal transit times as well as variability in hepatic function make it an unpredictable and unreliable way of giving drugs. Buccal and sublingual Avoids the problem of oral absorption and first-pass .