What is the limit of osmolarity for parenteral nutrition formulas used in

peripheral line administration?

Concerns about the osmolarity of peripheral parenteral nutrition (PPN) formulas 

thrombophlebitis

incidence of thrombophlebitis is estimated ato range from a low of

2.3% to as high as

70%. 

The range is this wide as there are many variables to consider

osmolarity PPN additives such as heparin and

lipids duration of PPN administration the types of catheters and needles

used

So, although the etiology of

thrombophlebitis in PPN is often multifactorial, the osmolarity of the infused PPN solution may be an important variable. 

To decrease the likelihood of phlebitis, the osmolarity of PPN

should be between 600 and

900 mOsm.

For solutions with an osmolarity of

1100 mOsm or greater, lipid emulsion may be added to increase the patient's tolerance for the infusion. However, this approach is not recommended for patients with contraindications,

such as

 high triglycerides.

Alternatively

hydrocortisone and heparin can be added to hyperosmolar solutions of up to

1200 mOsm to prevent phlebitis.

Addition of heparin to PN solutions “reduces the formation of a fibrin sheath around the catheter, may

reduce phlebitis… and increases the duration of catheter patency” (Groh-Wargo, et al., 2000). Heparin also

stimulates the release of lipoprotein lipase, which may improve lipid clearance.

This approach may not be appropriate for all types of patients. For example, heparin should be avoided in patients with a history of heparin-induced thrombocytopenia. In addition, hydrocortisone and heparin may not be stable additives for all PPN solutions, especially those containing fat emulsion.

calculating the osmolarity of PPN solutions

Osmolarity (mOsm/L) = (grams dextrose / liter) x 5] + [grams amino acid / liter) x 10] + [(mEq cations / liter) x 2]

Another way

Osmolarity (mOsm/L) =(Amino acid×8)+(glucose ×7)+(Na×2)+(phosphorus×0.2)- 50

Because of the limitations in osmolarity of PPN solutions, the typical PPN composition provides a final concentration of amino acids that is

generally between 2.5% (25 g/L)

and 5% (50 g/L). Dextrose concentrations

NaCL0.9%

LR NaCL3%

ALBUM5%

NaHCO3 D10%

D5 1/2NS

D5NS

KCL

Na(mEq/L)

154 130 513 130-160

4.2?%(.5mEq/ml)8.4%(1mEq/ml)

154

CL(mEq/L)

154 109 513 130-160

0 154

K(mEq/L)

0 4 0 0 0 0 1ml=2mEq

Osmolarity(mOsm/L)

308 275 1025 310 8.4%(2000)

505 406 560 4000

Lactate(mEq/L)

0 28 0 0 0 0 0 0

Dextrosegm/L

0 0 0 0 0 100 50 50

TPN SOLUTIONSAMINOSIN 15% amino acid 1300

TRAVASOL 10% amino acid 998

LIPID 10% 276

LIPID 20% 258

NOVAMINE15% amino acid 1388

HEPTAMINE 8 % amino acid 785