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PERIPHERAL ACCESS SITES
PARENTERAL NUTRITION FOR PA R E N T E R A L
CAROL J. ROLLINS, MS, RD, PH A R MD , N U T R I T I O N
BCNSP COORDINATOR, NUTRITION SUPPORT SERVICE/ Access for parenteral
CLINICAL PHARMACIST FOR HOME INFUSION, nutrition is generally
ARIZONA HEALTHSCIENCES CENTER TUCSON, ARIZONA obtained by placement
of a central ve n o u s
P arenteral nutrition (PN) is an appropriate route of catheter. Cannulation of
nutrition support when patients with identified malnu- the subclavian, internal
trition or significant risk of malnutrition cannot meet jugular, or femoral veins
their nutritional requirements through the gastroin- with advancement of
1 the catheter tip into the
testinal (GI) tract. Although typically referred to as superior or inferior vena cava ach i eves central
T P N, an acronym for total parenteral nutrition, venous access. Catheter tip placement elsewhere
patients who tolerate some oral intake or tube feeding than the vena cava is considered peripheral access.
require delivery of only part of their nutrients via the Based on catheter tip location, the Intrave n o u s
parenteral route. Use of the GI tract is encouraged to Nursing Society (INS) recognizes peripheral catheters
the extent possible. Septic complications may be as midclavicular, midline, and short peripheral.4,5
reduced and gut villi better preserved with administra- Acceptable dwell time differs for these 3 categories;
2 , 3
tion of at least some nutrients into the GI tract.
continued pg 2
Peripheral continued
however, risk of vascular irritation or damage and thrombosis requires Larger veins, such as the median,
that guidelines for peripheral administration be imposed for all classes cephalic, or basilic veins in the
of peripheral catheters. Guidelines include limiting dextrose concentra- forearm, are preferred for hyper-
tions and hypertonicity of substances administered, since dilution by tonic or irritating substances, for
blood flow is less than with central venous administration. Parenteral larger volume infusions, and for
nutrition administered via the peripheral venous route, known as therapies administered using a
10
peripheral parenteral nutrition or PPN, must be formulated with these pump. PPN fits all these criteria.
limitations in mind. Typical indications for PPN include short-term use, Midclavicular lines are generally
modest needs, and contraindications to central access (subclavian or inserted through the basilic or
jugular catheters) placement, such as radical neck dissection. cephalic veins of the upper arm or
at the antecubital fossa and
CAUSES OF INFUSION-SITE FA I L U R E extend at least to the proximal
axillary vein, where vein size and
Several factors related to the cannula, patient, and infusate blood flow are relatively large.
influence the ability to provide PPN successfully. Acquiring and Midline catheters are inserted
maintaining access for an appropriate period of time is essen- through veins in the antecubital
tial. Infusion site failure is manifested by phlebitis, thrombosis, fossa and extend 5 to 7 inches
or infiltration/extravasation. into the vessel, where vein diam-
eter is still about 5 to 6 millime-
• Phlebitis is inflammation of a vein, and is characterized ters.5,11 Short peripheral catheters
by erythema with or without pain. It may include a visual generally extend less than 3 inch-
streak along the vein, edema, and hardening of the vein es into a superficial vein.4 Vein
(cord formation).4 diameter here is smaller, and
dwell time is generally limited to a
• Thrombosis is formation of a blood clot within the vessel. f ew days. Site rotation and
• Thrombophlebitis is a combination of phlebitis and peripheral catheter replacement
thrombosis. every 48 to 72 hours is com-
mon.11-14 The cumulative risk of
• Infiltration is leakage of a non-vesicant product into tissue. complications increases each day
that a catheter is in place. The
• Extravasation is the proper term when the product risk remains at 10% to 15% per
4 6,15
is a vesicant. day from day 2 until day 4.
Use of superficial veins in the
The reported incidence of phlebitis or thrombophlebitis ranges upper extremities allows proper
from 2.3% up to approximately 80%,4,6-9 and an incidence of up assessment for complications.1 2
to 45% is reported for infiltration/extravasation.6 Guidelines from the INS and the
Centers for Disease Control
strongly recommend that only
veins in the upper extremities be
SITES OF CANNULAT I O N cannulated in adults, since the
risk of deep vein thrombosis is
The site of cannulation, cannula size and dwell time, insertion tech- increased in the lower extremi-
nique, and catheter care affect development of complications that may ties.4,11,12,16 Selection of the small-
result in infusion site failure. est gauge and shortest catheter
acceptable for administration of
22
therapy may help limit complica- which in turn dictates the amount I M P O RTANCE OF LIPID EMULSION
tions. The catheter must be in a of fluid and lipid emulsion neces- Lipid emulsion appears to provide
vein of adequate diameter to sary. In general, it is difficult to protection to the vein and allows
a l l ow blood flow around the provide adequate support via PPN tolerance to higher osmolarity
catheter and hemodilution of the for a patient with severe metabol- infusates. Animal studies demon-
4,13
infusate. ic stress or nutritional depletion strate reduced endothelial dam-
Successful PPN therapy requires requiring electrolyte replacement age from amino acid solutions
an adequate number of healthy and high calorie or protein intake. when fat emulsion is also
17,18
veins for cannulation when short infused. Venous patency time
peripheral catheters are used. was improved in neonates given
Patients with poor ve n o u s a high-fat formulation versus
access are rarely acceptable It is difficult to provide a lowe r-fat formulation of
candidates for PPN thera- “ the same osmolarity.1 9
py, unless midline or mid- adequate support via PPN A longer patency time was
clavicular access can be for a patient with severe also noted when the
attained. Veins tend to lose metabolic stress or neonates received a lower
supporting tissue and nutritional depletion osmolarity PPN formu l a t i o n
become elongated and tortuous ” (547 mOsm/L vs 702 mOsm/L
with age.1 3 Veins are generally and 702 mOsm/L vs 784
smaller and more fragile in older mOsm/L) in a paired crossover
patients than in younger patients. Parenteral support for more than study design.19
Those with a history of long-term a few days, even at lower levels of
corticosteroid use, severe malnu- calorie and protein provision, is T O TAL NUTRIENT ADMIXTURE
trition, and debilitating diseases difficult to maintain with short Vein tolerance to hyposmolar
also tend to have small fragile peripheral catheters. Midline or f o r mulations may be further
veins. Repeated intravenous ther- midclavicular catheter placement i m p r oved by admixture of the
apies can result in venous trauma should be considered when PPN is lipid emulsion with the dextrose-
and scarring, which limit periph- expected to be necessary for amino acid solution (total nutrient
eral access. more than 1 week. Barring any admixture [TNA]). This beneficial
complications, midline catheters effect may be secondary to
I N D I C ATIONS OF PPN can remain in place for up the increase in pH of the TNA
to 4 weeks and midclav i c u l a r formulation and may be negated
4,5
PPN is useful for supplementation catheters for up to 3 months. since peripheral vein TNAs are
of inadequate oral or tube feeding notoriously unstable admixtures
intake, hypocaloric support with F O R M U L ATIONS compared with central TNAs.2 0
low to moderate protein provi- FOR PPN In a randomized trial comparing
sion, transitional support until Infusate-related factors influence co-infused lipids with admixed
central access can be obtained, venous complications and patient lipids, significantly better vein
and temporary support until tolerance to PPN. Preparations of tolerance was noted with
catheter replacement follow i n g dextrose with normal saline and the admixed formu l a t i o n .2 1
recurrent catheter-related sepsis. dextrose with amino acid solution Tolerance to osmolarities of
Current nutritional status and consistently result in peripheral approximately 1300 mOsm/L for
underlying conditions help deter- vein phlebitis when the osmolari- formulations admixed with lipid
mine nutritional requirements, ty exceeds 900 mOsm/L.6 have been reported.22,23
M . V.I. N E W S L I N E S, SPONSORED BY ASTRAZENECA LP 3
Another report noted no problems in 63% of patients receiving a PPN M A C R O N U T R I E N T S
formulation with admixed lipids having an osmolarity of 1146 mOsm/L.
Twenty-three percent of patients experienced transient pain, and 14% Macronutrient concentrations are
had the infusion stopped.24 This suggests that osmolarities in the range typically limited in PPN formula-
of 1100 mOsm/L to 1300 mOsm/L are acceptable when lipid emulsion tions because of osmolarity. The
is admixed with dextrose-amino acid solutions. Caution with these high- final concentration of amino
er osmolarities is advised. acids is generally between 2.5%
(25 g/L) and 5% (50 g/L) for
REDUCING THE RISKS FOR THROMBOSIS AND PHLEBITIS P P N.3 2 Specialized amino acid
solutions are rarely appropriate
Addition of low-dose heparin and hydrocortisone to PPN formulations for PPN, since the patient popula-
may increase tolerance to hyperosmolar formulations. The incidence of tions for which such products are
vein thrombosis appears to be reduced by addition of low-dose heparin designed tend to be poor candi-
25,26
(1 unit/mL) to peripherally administered fluids. Premature infants dates for PPN therapy.
receiving 1 unit of heparin per milliliter of PPN had about one-third the
incidence of thrombophlebitis (5.7% vs 17.2%) and nearly double the The generally recognized upper
duration of catheter patency of those without heparin.25 Adding 10 mg/L limit for dextrose concentrations
of hydrocortisone and 1000 units of heparin per liter to infusion solu- in PPN formulations is 10%
tions of 5% dextrose or 5% dextrose with 0.45% sodium chloride pro- for adults (approximately 500
duced nearly the same results in phlebitis as buffering the solutions (pH mOsm/L) and 12.5% for pediatric
7.2 to 7.5).27 Heparin should be avoided in patients with a history of patients (625 mOsm/L). At these
heparin-induced thrombocytopenia. Significant reduction of peripheral concentrations, dextrose pro-
vein thrombophlebitis has been reported in ran- vides 340 Kcal/L in adults and
domized placebo controlled trials with 425 Kcal/L in pediatric patients.
use of transdermal glyceryl trinitrate Glycerol (glycerin) has also
in both PPN and non-PPN The incidence of vein been used as a carbohy-
p a t i e n t s .2 8 - 3 0 In normal healthy “ drate source in com-
subjects, application of a topi- thrombosis appears to be mercially prepared
cal nonsteroidal anti-inflamma- reduced by addition of PPN solutions. The
tory agent to the cannulation low-dose heparin neutral pH, higher
site on one arm reduced the inci- (1 unit/mL) to peripherally caloric density (4.3
dence of phlebitis by nearly half in administered fluids. Kcal/g), and trihydroxy
comparison with the site on the other ” alcohol structure of glyc-
arm, which served as a placebo.31 erin favor its use in PPN.
OSMOLARITY OF THE PPN FORMULAT I O N Lipid emulsion provides a major
source of calories in PPN formula-
The prescription for a PPN formulation has a significant influence on tions, since calories from carbo-
how well the therapy will be tolerated. As previously mentioned, osmo- hydrates are limited by the osmo-
larity is a critical consideration. Dextrose, amino acids, and electrolytes larity. Guidelines suggest that fats
are the major contributors to osmolarity. The osmolarity can be be provided at no more than 60%
estimated as shown in the boxed equation that follows. of total calories and no more than
1.5 g/kg of body weight per day
in adults.33 The maximum recom-
OSMOLARITY (m O s m / L) =
(GRAMS DEXTROSE/LITER) x 5 + (GRAMS AMINO ACID/LITER) x 10 + mended dose of lipids in children
(m E q C ATIONS/LITER) x 2 and adolescents is 2.0 g/kg/d to
2.5 g/kg/d. Infants may tolerate
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