PERIPHERAL ACCESS SITES PARENTERAL NUTRITION · 22 however, risk of vascular irritation or damage and thrombosis requires that guidelines for peripheral administration be imposed

P

continued pg 2

ACCESS SITES FOR PA R E N T E R A LN U T R I T I O N

Access for parenteralnutrition is generallyobtained by placement of a central ve n o u scatheter. Cannulation ofthe subclavian, internaljugular, or femoral veinswith advancement ofthe catheter tip into the

superior or inferior vena cava ach i eves centralvenous access. Catheter tip placement elsewherethan the vena cava is considered peripheral access.Based on catheter tip location, the Intrave n o u sNursing Society (INS) recognizes peripheral cathetersas midclavicular, midline, and short peripheral.4,5

Acceptable dwell time differs for these 3 categories;

PERIPHERAL PARENTERAL NUTRITIONCAROL J. ROLLINS, MS, RD, PH A R MD ,

BCNSP COORDINATOR, NUTRITION SUPPORT SERVICE/

CLINICAL PHARMACIST FOR HOME INFUSION,

ARIZONA HEALTH SCIENCES CENTER TUCSON, ARIZONA

arenteral nutrition (PN) is an appropriate route ofnutrition support when patients with identified malnu-trition or significant risk of malnutrition cannot meettheir nutritional requirements through the gastroin-testinal (GI) tract.1 Although typically referred to asT P N, an acronym for total parenteral nutrition,patients who tolerate some oral intake or tube feedingrequire delivery of only part of their nutrients via theparenteral route. Use of the GI tract is encouraged tothe extent possible. Septic complications may bereduced and gut villi better preserved with administra-tion of at least some nutrients into the GI tract.2 , 3

22

however, risk of vascular irritation or damage and thrombosis requiresthat guidelines for peripheral administration be imposed for all classesof peripheral catheters. Guidelines include limiting dextrose concentra-tions and hypertonicity of substances administered, since dilution byblood flow is less than with central venous administration. Parenteralnutrition administered via the peripheral venous route, known asperipheral parenteral nutrition or PPN, must be formulated with theselimitations in mind. Typical indications for PPN include short-term use,modest needs, and contraindications to central access (subclavian orjugular catheters) placement, such as radical neck dissection.

CAUSES OF INFUSION-SITE F A I L U R E

Several factors related to the cannula, patient, and infusateinfluence the ability to provide PPN successfully. Acquiring andmaintaining access for an appropriate period of time is essen-tial. Infusion site failure is manifested by phlebitis, thrombosis,or infiltration/extravasation.

• Phlebitis is inflammation of a vein, and is characterizedby erythema with or without pain. It may include a visualstreak along the vein, edema, and hardening of the vein(cord formation).4

• Thrombosis is formation of a blood clot within the vessel.

• Thrombophlebitis is a combination of phlebitis andthrombosis.

• Infiltration is leakage of a non-vesicant product into tissue.

• Extravasation is the proper term when the product is a vesicant.4

The reported incidence of phlebitis or thrombophlebitis rangesfrom 2.3% up to approximately 80%,4,6-9 and an incidence of upto 45% is reported for infiltration/extravasation.6

SITES OF CANNULAT I O N

The site of cannulation, cannula size and dwell time, insertion tech-nique, and catheter care affect development of complications that mayresult in infusion site failure.

Peripheral continued

Larger veins, such as the median,cephalic, or basilic veins in theforearm, are preferred for hyper-tonic or irritating substances, forlarger volume infusions, and fortherapies administered using apump.10 PPN fits all these criteria.Midclavicular lines are generallyinserted through the basilic orcephalic veins of the upper arm orat the antecubital fossa andextend at least to the proximalaxillary vein, where vein size andblood flow are relatively large.

Midline catheters are insertedthrough veins in the antecubitalfossa and extend 5 to 7 inchesinto the vessel, where vein diam-eter is still about 5 to 6 millime-ters.5,11 Short peripheral cathetersgenerally extend less than 3 inch-es into a superficial vein.4 Veindiameter here is smaller, anddwell time is generally limited to af ew days. Site rotation andperipheral catheter replacementevery 48 to 72 hours is com-mon.11-14 The cumulative risk ofcomplications increases each daythat a catheter is in place. Therisk remains at 10% to 15% perday from day 2 until day 4.6,15

Use of superficial veins in theupper extremities allows properassessment for complications.1 2

Guidelines from the INS and theCenters for Disease Controlstrongly recommend that onlyveins in the upper extremities becannulated in adults, since therisk of deep vein thrombosis isincreased in the lower extremi-ties.4,11,12,16 Selection of the small-est gauge and shortest catheteracceptable for administration of

M . V. I . N E W S L I N E S , SPONSORED BY ASTRAZENECA LP 3

therapy may help limit complica-tions. The catheter must be in avein of adequate diameter toa l l ow blood flow around thecatheter and hemodilution of theinfusate.4,13

Successful PPN therapy requiresan adequate number of healthyveins for cannulation when shortperipheral catheters are used.Patients with poor ve n o u saccess are rarely acceptablecandidates for PPN thera-py, unless midline or mid-clavicular access can beattained. Veins tend to losesupporting tissue andbecome elongated and tortuouswith age.1 3 Veins are generallysmaller and more fragile in olderpatients than in younger patients.Those with a history of long-termcorticosteroid use, severe malnu-trition, and debilitating diseasesalso tend to have small fragileveins. Repeated intravenous ther-apies can result in venous traumaand scarring, which limit periph-eral access.

I N D I C ATIONS OF PPN

PPN is useful for supplementationof inadequate oral or tube feedingintake, hypocaloric support withlow to moderate protein provi-sion, transitional support untilcentral access can be obtained,and temporary support untilcatheter replacement follow i n grecurrent catheter-related sepsis.

Current nutritional status andunderlying conditions help deter-mine nutritional requirements,

which in turn dictates the amountof fluid and lipid emulsion neces-sary. In general, it is difficult toprovide adequate support via PPNfor a patient with severe metabol-ic stress or nutritional depletionrequiring electrolyte replacementand high calorie or protein intake.

Parenteral support for more thana few days, even at lower levels ofcalorie and protein provision, isdifficult to maintain with shortperipheral catheters. Midline ormidclavicular catheter placementshould be considered when PPN isexpected to be necessary formore than 1 week. Barring anycomplications, midline catheterscan remain in place for up to 4 weeks and midclav i c u l a rcatheters for up to 3 months.4,5

F O R M U L ATIONS FOR PPN

Infusate-related factors influencevenous complications and patienttolerance to PPN. Preparations ofdextrose with normal saline anddextrose with amino acid solutionconsistently result in peripheralvein phlebitis when the osmolari-ty exceeds 900 mOsm/L.6

I M P O RTANCE OF LIPID EMULSION

Lipid emulsion appears to provideprotection to the vein and allowstolerance to higher osmolarityinfusates. Animal studies demon-strate reduced endothelial dam-age from amino acid solutionswhen fat emulsion is alsoinfused.17,18 Venous patency timewas improved in neonates given

a high-fat formulation versus a lowe r-fat formulation of

the same osmolarity.1 9

A longer patency time wasalso noted when theneonates received a lower

osmolarity PPN formu l a t i o n(547 mOsm/L vs 702 mOsm/L

and 702 mOsm/L vs 784mOsm/L) in a paired crossoverstudy design.19

T O TAL NUTRIENT ADMIXTURE

Vein tolerance to hyposmolar f o r mulations may be furtheri m p r oved by admixture of thelipid emulsion with the dextrose-amino acid solution (total nutrientadmixture [TNA]). This beneficialeffect may be secondary to the increase in pH of the TNA formulation and may be negatedsince peripheral vein TNAs arenotoriously unstable admixturescompared with central TNAs.2 0

In a randomized trial comparingco-infused lipids with admixedlipids, significantly better vein tolerance was noted with the admixed formu l a t i o n .2 1

Tolerance to osmolarities ofapproximately 1300 mOsm/L forformulations admixed with lipidhave been reported.22,23

“It is difficult to provide adequate support via PPN for a patient with severe

metabolic stress or nutritional depletion”

4

Another report noted no problems in 63% of patients receiving a PPNformulation with admixed lipids having an osmolarity of 1146 mOsm/L.Twenty-three percent of patients experienced transient pain, and 14%had the infusion stopped.24 This suggests that osmolarities in the rangeof 1100 mOsm/L to 1300 mOsm/L are acceptable when lipid emulsionis admixed with dextrose-amino acid solutions. Caution with these high-er osmolarities is advised.

REDUCING THE RISKS FOR THROMBOSIS AND PHLEBITIS

Addition of low-dose heparin and hydrocortisone to PPN formulationsmay increase tolerance to hyperosmolar formulations. The incidence ofvein thrombosis appears to be reduced by addition of low-dose heparin(1 unit/mL) to peripherally administered fluids.25,26 Premature infantsreceiving 1 unit of heparin per milliliter of PPN had about one-third theincidence of thrombophlebitis (5.7% vs 17.2%) and nearly double theduration of catheter patency of those without heparin.25 Adding 10 mg/Lof hydrocortisone and 1000 units of heparin per liter to infusion solu-tions of 5% dextrose or 5% dextrose with 0.45% sodium chloride pro-duced nearly the same results in phlebitis as buffering the solutions (pH7.2 to 7.5).27 Heparin should be avoided in patients with a history ofheparin-induced thrombocytopenia. Significant reduction of peripheralvein thrombophlebitis has been reported in ran-domized placebo controlled trials withuse of transdermal glyceryl trinitratein both PPN and non-PPNp a t i e n t s .2 8 - 3 0 In normal healthysubjects, application of a topi-cal nonsteroidal anti-inflamma-tory agent to the cannulationsite on one arm reduced the inci-dence of phlebitis by nearly half incomparison with the site on the otherarm, which served as a placebo.31

OSMOLARITY OF THE PPN FORMULAT I O N

The prescription for a PPN formulation has a significant influence onhow well the therapy will be tolerated. As previously mentioned, osmo-larity is a critical consideration. Dextrose, amino acids, and electrolytesare the major contributors to osmolarity. The osmolarity can be estimated as shown in the boxed equation that follows.

OSMOLARITY (m O s m / L) =

(GRAMS DEXTROSE/LITER) x 5 + (GRAMS AMINO ACID/LITER) x 10 +

(m E q C ATIONS/LITER) x 2

M A C R O N U T R I E N T S

Macronutrient concentrations aretypically limited in PPN formula-tions because of osmolarity. Thefinal concentration of aminoacids is generally between 2.5%(25 g/L) and 5% (50 g/L) forP P N.3 2 Specialized amino acidsolutions are rarely appropriatefor PPN, since the patient popula-tions for which such products aredesigned tend to be poor candi-dates for PPN therapy.

The generally recognized upperlimit for dextrose concentrationsin PPN formulations is 10% for adults (approximately 500mOsm/L) and 12.5% for pediatricpatients (625 mOsm/L). At theseconcentrations, dextrose pro-vides 340 Kcal/L in adults and425 Kcal/L in pediatric patients.

Glycerol (glycerin) has alsobeen used as a carbohy-

drate source in com-mercially preparedPPN solutions. Theneutral pH, higher

caloric density (4.3Kcal/g), and trihydroxy

alcohol structure of glyc-erin favor its use in PPN.

Lipid emulsion provides a majorsource of calories in PPN formula-tions, since calories from carbo-hydrates are limited by the osmo-larity. Guidelines suggest that fatsbe provided at no more than 60%of total calories and no more than1.5 g/kg of body weight per dayin adults. 33 The maximum recom-mended dose of lipids in childrenand adolescents is 2.0 g/kg/d to2.5 g/kg/d. Infants may tolerate

“The incidence of veinthrombosis appears to be

reduced by addition of low-dose heparin

(1 unit/mL) to peripherallyadministered fluids.”

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slightly more lipids. The cumula-tive effect of macronutrient con-centrations on lipid stability mustbe considered when the PPN is tobe provided as a TNA formula-tion.32

M I C R O N U T R I E N T S

The micronutrient components ofPPN are similar to those of centrally administered TPN for-mulations, with a few exceptions.Vitamins should be administereddaily using a product such as M.V. I .®-12 (MultivitaminInfusion) that meets the guide-lines for parenteral vitamins setby the American MedicalAssociation Nutritional AdvisoryGroup. M.V.I.®-12 does not con-tain vitamin K, which should beadministered separately ifneeded. Additional sup-plementation to correcta ny existing deficien-cies is also appropri-ate.34 Direct addition ofM.V.I.-12 to intravenousfat emulsions is not rec-ommended. Trace elementscan be routinely added to all par-enteral nutrition formu l a t i o n s ,although the short duration ofmost PPN therapy makes thisunnecessary unless the patienthas preexisting deficiencies.Electrolytes such as sodium chlo-r i d e, potassium, magnesium,p h o s p h a t e, and calcium areessential for muscular and centralnervous system functions, as wellas for metabolism and mainte-nance of fluid status.35

GUIDELINES FOR MONITORING THERAPY

Monitoring of PPN therapy is essentially the same as for parenteral nutri-tion administered via a central venous access device. Metabolic compli-cations parallel those associated with central parenteral nutrition. Thetypical duration of PPN therapy and limitations on carbohydrate provision in PPN—with a subsequent increase in calories from lipidemulsion—may alter the incidence of hyperglycemia and hypertriglyc-eridemia. The frequency of monitoring should be based on the overallcondition of the patient, on the presence of factors that may contributeto complications, and response to alterations in the nutrient prescrip-tion. Since PPN patients tend to be under less metabolic stress thanmost TPN patients, the frequency of laboratory monitoring may be lessfrequent.

S U M M A RY

Peripheral parenteral nutrition can be a safe and effective therapy.Achieving peripheral vein access and subsequently maintaining accessis critical to providing PPN therapy. Patient selection is greatly influ-

enced by the condition of peripheral veins.The PPN formulation is designed to

minimize venous damage whilep r oviding adequate nutrition

support. This is achieved bylimiting dextrose, amino acid,and electrolyte concentrationsin the PPN formulation, and

providing a higher percentage ofcalories from lipid emulsions and

giving more fluid than is typically usedfor central parenteral nutrition.

Micronutrients (vitamins and trace elements) are also prov i d e d .Peripheral parenteral nutrition support is generally considered a short-term therapy. Patients experiencing relatively low metabolic stress aremost likely to achieve short-term nutritional goals with PPN therapy. Inhigh stress patients, nutritional deterioration may be blunted until cen-tral venous access can be achieved.

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“As with TPN, vitamins should be

administered daily.”

Intravenous therapy in the older adult:special needs and consider-ations. J Intraven Nurs. 1996;19:251-55. 1 4 . Ena J, Cercenado E,Martinez D et al. Cross-sectional epidemiology of phlebitis andc a t h e t e r-related infections. Infect Control Hosp Epidemiol.1992;13:15-20. 1 5 . Homer LD, Holmes KR. Risks associated with72- and 96-hour peripheral intravenous catheter dwell times. JIntraven Nurs. 1998;21:301-305. 1 6 . Centers for Disease Control.Guidelines for prevention of intravascular infection. J NatlIntraven Ther Assoc. 1982;5:39-50. 1 7 . Fujiwara T, Kawarasaki H,Fonkalsrud EW. Reduction of post-infusion venous endotheliali n j u ry with Intralipid. Surg Gynecol Obstet . 1984;158:57-65. 1 8 .Enger E, Jacobsson B, Sorensen SE. Tissue toxicity of intravenoussolutions. Acta Paediatr Scand. 1976;65:248-252. 1 9 . Pineault M,Chessex P, Piedboeuf B, Bisaillon S. Beneficial effect of coinfusinga lipid emulsion on venous patency. J Parenter Enteral Nutr.1989;13:637-640. 2 0 . Li LC, Sampogna TP. A factorial designstudy on the physical stability of 3-in-1 admixtures. J PharmPharmacol. 1993;45:985-7. 2 1 . Nordenstrom J, Jeppsson B,Loven L, Larsson J. Peripheral parenteral nutrition: effect of astandardized compounded mixture on infusion phlebitis. Br JS u r g . 1991;78:1391-1394. 2 2 . Hoheim DF, O’Callaghan TA ,Joswiak BJ, et al. Clinical experience with three-in-one admixturesadministered peripherally. Nutr Clin Pract. 1990;5:118-122. 2 3 .Watson LA, Bommarito AA, Marshall JF. Total peripheral parenter-al nutrition in pregnancy. J Parenter Enteral Nutr. 1 9 9 0 ; 1 4 : 4 8 5 -489. 2 4 . Hoffmann E. A randomized study of central versusperipheral intravenous nutrition in the perioperative period. ClinNutr. 199;8:179-180. 2 5 . Alpan G, Eyal F, Springer C, et al.Heparinization of alimentation solutions administered throughperipheral veins in premature infants: a controlled study.Pediatrics. 1984;74:375-378. 2 6 . Daniell HW. Heparin in the pre-vention of infusion phlebitis: a double-blind controlled study.JAMA. 1973;226:1317-1321. 2 7 . Fonkalsrud EW, Carpenter K,Masuda Y, Beckerman JH. Prophylaxis against postinfusionphlebitis. Surg Gynecol Obstetr. 1971;133:253-256. 2 8 . K h a w a j aH T, Williams JD, Weaver PC. Transdermal glyceryl trinitrate toallow peripheral total parenteral nutrition: a double-blind placebocontrolled feasibility study. J R Soc Med. 1991;84:69-71. 2 9 .Tighe MJ, Wong C, Martin IG, McMahon MJ. Do heparin, hydro-cortisone, and glyceryl trinitrate influence thrombophlebitis duringfull intravenous nutrition via a peripheral vein? J Parenter EnteralNutr. 1995;19:507-509. 3 0 . Khawaja HT, O’Brien BJ, Buxton MJ.Cost minimisation study of transdermal glyceryl trinitrate inreducing failure of peripheral intravenous infusions. Br J Med.1989;76:299-297. 3 1 . Payne-James JJ, Bray MJ, Kapadia S, et al.Topical nonsteroidal anti-inflammatory gel for the prevention ofperipheral vein thrombophlebitis. Anaesthesia. 1992;47:324-326.3 2 . Rollins CJ. Total nutrient admixtures: stability issues and theirimpact on nursing practice. J Intraven Nurs. 1997;20:299-304.3 3 . Lenssen P. Management of total parenteral nutrition. In:Skipper A, ed. Dietitian’s Handbook of Enteral and ParenteralNutrition. 2nd ed. Gaithersburg, Md: Aspen Publ; 1998:481-513.3 4 . The National Advisory Group on Standards and PracticeGuidelines for Parenteral Nutrition. Safe practices for parenteralnutrition formulations. J Parenter Enteral Nutr. 1 9 9 8 ; 2 2 : 4 9 - 6 6 .3 5 . Silberman H, Eisenberg D. Nutritional requirements. In:Parenteral and Enteral Nutrition for the Hospitalized Patient. E a s tN o rwalk, Conn: Appleton-Century-Crofts; 1982:52-73.●