Archive:Total parenteral nutrition

2007-11-16T01:54:56Z

71.199.30.19: /* Complications */

[[Image:Tpn_3bag.jpg|thumb|Home TPN formula]]

'''Total parenteral nutrition''' (TPN), is the practice of feeding a person [[intravenous]]ly, bypassing the usual process of [[eating]] and [[digestion]]. The person receives nutritional formulas containing [[salt]]s, [[glucose]], [[amino acid]]s, [[lipid]]s and added [[vitamin]]s.

==General Usage==

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TPN is normally used following surgery, when feeding by mouth or using the [[gut]] is not possible, when a person's digestive system cannot absorb nutrients due to [[chronic (medicine)|chronic disease]], or, alternatively, if a person's nutrient requirement cannot be met by [[enteral feeding]] (tube feeding) and supplementation. It has been used for [[Coma|comatose]] patients, although enteral feeding is usually preferable, and less prone to complications. Short-term TPN may be used if a person's digestive system has shut down (for instance by [[Peritonitis]]), and they are at a low enough weight to cause concerns about nutrition during an extended hospital stay. Long-term TPN is occasionally used to treat people suffering the extended consequences of an accident or surgery. Most controversially, TPN has extended the life of a small number of children born with nonexistent or severely birth-deformed guts. The oldest were eight years old in [[2003]].

The preferred method of delivering TPN is with a medical [[infusion pump]]. A [[sterilization (microbiology)|sterile]] bag of nutrient solution, between 500 mL and 4 L is provided. The pump infuses a small amount (0.1 to 10 mL/hr) continuously in order to keep the vein open. Feeding schedules vary, but one common regimen ramps up the nutrition over a few hours, levels off the rate for a few hours, and then ramps it down over a few more hours, in order to simulate a normal set of meal times.

The nutrient solution consists of [[water]], [[glucose]], [[salt]]s, [[amino acid]]s, [[vitamin]]s and (more controversially) sometimes emulsified [[fat]]s. Long term TPN patients sometimes suffer from lack of trace nutrients or [[electrolyte]] imbalances. Because increased [[blood sugar]] commonly occurs with TPN, [[insulin]] may also be added to the infusion. Often though, an insignificant amount of insulin is added, sometimes 10 units or less in 2 liters of TPN. In actuality, the patient will probably get less than that. Occasionally, other drugs are added as well, sometimes unnecessarily.

Chronic TPN is performed through a central intravenous catheter, usually in the subclavian or jugular vein. Another common practice is to use a [[PICC line]], which originates in the arm, and exends to one of the central veins, such as the subclavian. In infants, sometimes the [[umbilical vein]] is used.

Battery-powered ambulatory infusion pumps can be used with chronic TPN patients. Usually the pump and a small (100 ml) bag of nutrient (to keep the vein open) are carried in a small bag around the waist or on the shoulder. Outpatient TPN practices are still being refined.

Aside from their dependence on a pump, chronic TPN patients live quite normal lives.

==Complications==

The most common complication of TPN use is bacterial infection, usually due to the increased infection risk from having an indwelling [[central venous catheter]]. [[Liver]] [[Liver failure|failure]] may sometimes occur; a recent study at Children's Hospital Boston on the cause suggests it is due to a large difference in omega-6 to omega-3 ratio. When treated with [[Omegaven]], a different fatty acid infusion (which is approved for limited use in the U.S.), two patients were able to recover from their condition.<ref>[http://pediatrics.aappublications.org/cgi/content/full/118/1/e197?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=parenteral+nutrition&searchid=1&FIRSTINDEX=0&volume=118&issue=1&resourcetype=HWCIT| Gura KM, Duggan CP, Collier SB, et al. Reversal of parenteral nutrition-associated liver disease in two infants with short bowel syndrome using parenteral fish oil: implications for future management. ''Pediatrics'' Vol. 118 No. 1 July 2006 p197-201]</ref>

Two related common complications of TPN are [[venous thrombosis]] and [[priapism]]. Fat infusion during TPN is assumed to contribute to both.<ref>[http://jpen.aspenjournals.org/cgi/content/abstract/16/2/171| X Hebuterne, AM Frere, J Bayle, and P Rampal Priapism in a patient treated with total parenteral nutrition ''Journal of Parenteral and Enteral Nutrition'' Vol. 16 No. 2 1992 p171-174]</ref>

Another complication of TPN is non-anion gap [[metabolic acidosis]].
===What to do if you run out of TPN===
If TPN is not avaliable it is important to hang an IV solution that is most simular to the dextros concentration of TPN. (I.e. 10% dextros in water.)

==See also==
* [[Intravenous drip]]
* [[Parenteral and Enteral Nutrition]]

==References==
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== External links ==
*[http://www.nutritioncare.org American Society for Parenteral and Enteral Nutrition]
*[http://www.heinrick.com/ryan/tpn.cfm TPN/PPN Calculator] by Ryan Heinrick
*[http://www.childrenshospital.org/newsroom/Site1339/mainpageS1339P1sublevel222.html "Why does prolonged TPN cause liver damage in infants?"], Children's Hospital Boston
*[http://grey.colorado.edu/shortgut/index.php/TPN-associated_Liver_Disease TPN-associated Liver Disease]
*[http://blogs.nutrishare.com TPN Blogs] on [http://www.Nutrishare.com Nutrishare] (a Home TPN provider)
*[http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a601166.html TPN Drug Information] from MedlinePlus NIH Database
*[http://www.worldhealthlibrary.com/uncategorized/tpn-site-care/ TPN Care] from the World Health Library
[[Category:nutrition]]
[[Category:intensive care medicine]]

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Archive:Petroleum seep

2006-12-04T22:14:05Z

71.199.236.57: /* See also */

A '''seep''' is a wet place where a [[liquid]], usually [[groundwater]], has oozed from the ground to the surface. Seeps are usually not flowing, with the liquid sourced only from underground.

The term seep may also refer to the movement of liquid [[hydrocarbons]] to the surface through fractures and fissures in the rock and between [[geological]] layers. Oil seeps are quite common: California has thousands of them. Much of the oil discovered in [[California]] during the 19th century was from observations of seeps.

Seeps may be a significant source of pollution.

==Coal Oil Point Seep Field==

One seep, the Coal Oil Point Seep Field offshore from [[Santa Barbara, California]] has a seep area of about three square kilometers, and releases about 40 tons per day of methane and about 19 tons of reactive organic gas ([[ethane]], [[propane]], [[butane]] and higher hydrocarbons), which is about the same as that released by all the cars and trucks in the county. The liquid [[petroleum]] produces a slick that is many kilometers long and when degraded by [[evaporation]] and [[weathering]], produces tar balls which wash up on the beaches for miles around.

This seep also releases on the order of 100 to 150 barrels of liquid petroleum per day. [http://seeps.geol.ucsb.edu/ Hornafius et al.] The Monterey formation contains about one billion barrels, so at the current leaking rate, it would be emptied of liquid petroleum in about 20,000 years if it were not being replenished. The estimated lifetime of the gas component is even shorter. The field produces about 9 cubic meters of gas per barrel of oil, and so there is about 9,000,000 cubic meters of gas in the reservoir. [http://seeps.geol.ucsb.edu/ Hornafius et al.] The seep would deplete this amount of gas in about 150 years.

:o

==References==
* Hornafius, J.S.Quigley, D.C., and Luyendyk, B.P. "The world's most spectacular marine hydrocarbon seeps (Coal Oil Point, Santa Barbara Channel, California): Quantification of Emissions", Journal of Geophysical Research, v.104, n. C9, pp. 20,703-20,711, September 15, 1999. [http://seeps.geol.ucsb.edu/]

==External links==
* [http://seeps.wr.usgs.gov/ Natural Oil and Gas Seeps in California]
* [http://seeps.geol.ucsb.edu/ Hyrdocarbon Seeps] This UCSB site has a collection of papers describing a major seep just offshore from Santa Barbara, California.

[[Category:Geology]]

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Archive:Total parenteral nutrition

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