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Selection of a large central vein in preference to a smaller peripheral vein for the administration of therapeutic agents is based on the nature and amount of fluid to be injected. Central veins are able to accommodate large amounts of fluid when shock or hemorrhage demands rapid replacement. The larger veins are less susceptible to irritation from caustic drugs and from hypertonic nutrient solutions administered during parenteral nutrition.
Sepsis is a potential complication of any intravenous therapy. It is especially dangerous for patients with central venous lines because they are seriously ill and less able to ward off infections. Careful cleansing of the insertion site, sterile technique during insertion, periodic changing of tubing and catheter, and firmly anchoring the catheter to prevent movement and irritation are all essential for the prevention of sepsis.
Formation of a clot at the tip of the catheter is indicated if the rate of flow of intravenous fluids decreases measurably or if there is no fluctuation of fluid in the fluid column. Preventive measures include maintaining a constant flow of intravenous fluids by IV pump or controller, periodic flushing of the catheter, heparin as prescribed, and looping and securing the catheter carefully to avoid kinks that impede the flow of fluids. Cardiac arrhythmias can occur if the tip of the catheter comes into contact with the atrial or ventricular wall. Changing the patient's position may eliminate the problem, but if ectopic rhythm persists, additional interventions are warranted.
An arterial line can also be used to monitor the central venous pressure. The waveform for a tracing of the pressure reflects contraction of the right atrium and the concurrent effect of the ventricles and surrounding major vessels. It consists of a, c, and v ascending (or positive) waves and x and y descending (or negative) waves. Since systolic atrial pressure (a) and diastolic (v) pressure are almost the same, the reading is taken as an average or mean of the two.
The normal range for CVP is 0 to 5 mm H2O. A reading of 15 to 20 mm usually indicates inability of the right atrium to accommodate the current blood volume. However, the trend of response to rapid administration of fluid is more significant than the specific level of pressure. Normally the right heart can circulate additional fluids without an increase in central venous pressure. If the pressure is elevated in response to rapid administration of a small amount of fluid, there is indication that the patient is hypervolemic in relation to the pumping action of the right heart. Thus, CVP is used as a guide to the safe administration of replacement fluids intravenously, particularly in patients who are subject to pulmonary edema. Central venous pressure indirectly indicates the efficiency of the heart's pumping action; however, pulmonary artery pressure is more accurate for this purpose.
A high venous pressure may indicate congestive heart failure, hypervolemia, cardiac tamponade in which the heart is unable to fill, or vasoconstriction, which affects the heart's ability to empty its chambers. Conversely, a low venous pressure indicates hypovolemia and possibly a need to increase fluid intake.
central/cen·tral/ (sen´tr'l) situated at or pertaining to a center; not peripheral.
Patient discussion about central
Q. Is fibromyalgia related to Central Nervous System? Is fibromyalgia related to Central Nervous System? Among men and women who is more prone to the symptoms of fibromyalgia?
"Little research has been conducted that measures the prevalence of fibromyalgia, and estimates vary widely as to the proportion of male versus female patients. A 1999 epidemiology study conducted in London found a female to male ratio of roughly three to one. However, a 2001 review of the research literature in Current Rheumatology Reports stated the ratio was nine to one."
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401 Wood Street
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Q. What happens in rehab centers? How do they “cure” alcoholics and drug addicts?