Registered Nurses´ Association of Ontario

Page 6 of 7  Main Menu   <<Back   Next>>

Prescribed Therapy – Characteristics of the Infusate

Nurses may wish to consult a clinical pharmacist in their organization, if available, to obtain further information regarding the characteristics of prescribed therapy, and potential impact on client outcomes.

pH

The pH scale is a measurement scale used to quantify the concentration of hydrogen ions (H+) in a solution. The scale runs from 0 to 14, with 0 to 6 being acidic, 7 neutral and 8 – 14 being alkaline (basic). What is critical to understand is that a small change in pH results in a large change in H+ ion concentration. The following table provides a comparison of pH values as an illustration of this concept (Stranz, 2002).

pH - Blood pH = 7.35 – 7.45

 

pH

Example

Drug

Acid

1

Stomach acid

  
 

2

Lemon juice

Vancomycin = 2.4
 

3

Vinegar

Ciprofloxacin = 3.3 – 4.6
Tobramycin = 3 – 6.5

Neutral

7

Tap water

Erythromycin = 6.5 – 7.7

Base

11

Ammonia

Acyclovir = 10.5 – 11.6
 

12

Mineral lime Ca(OH)2

Phenytoin (Dilantin) = 12
 

13

Draino®

  

Reference: Stranz, M. (2002). Adjusting pH and osmolarity levels to fit standards and practices. Journal of
Vascular Access Devices. Fall, 12-17

Osmolality

The concentration of particles dissolved in each solution is referred to as its osmolality. In human plasma, the concentration of dissolved particles is about 290 x 103 M, so its osmolality is 290 mOsm/L (Stranz, 2002).

Separate solutions containing the same amount of particles are called iso-osmotic. The term isotonic is used interchangeably with the term iso-osmotic. Normal saline is iso-osmotic/isotonic with blood and the venous endothelium. Solutions containing fewer particles (lower osmolality) than normal saline are called hypotonic. Administration of hypotonic solutions results in fluid moving into the more concentrated venous endothelial cells and blood cells.

Solutions containing more particles (higher osmolality) are called hypertonic. When hypertonic solutions are administered, they draw fluid from the endothelium and blood cells, resulting in the cells shrinking and being more susceptible to damage (Stranz, 2002).

Vesicant Drugs

The following list includes some commonly administered vesicant drugs capable of causing injury when the drug escapes from the intended vascular pathway into surrounding tissue (INS, 2000). It is not intended to be a comprehensive list, but rather an example for consideration.

Calcium Chloride
Calcium Gluconate
Dacarbazine
Daunorubicin
Dextrose 10%
Diazepam
Dopamine
Lorazepam
Metronidazole
Midazolam
Nitroprusside
Pentobarbital
Phenytoin (Dilantin)
Potassium Chloride 40meq
Promethazine (Phenergan)
Rifampin
Sodium Bicarbonate
Vancomycin
Vincristine

Diagnostic Contrast Media

All ionic contrast media should be considered potential vesicants, especially Diatrizoate products; those with an asterix include a statement in the Compendium of Pharmaceuticals and Specialities (CPA, 2004) under adverse reactions that extravasation may cause necrosis; those with no asterix have no monograph listed in CPS. Ionic Contrast Media include:

Non-ionic contrast media include (those with an asterix include a statement in the
CPS under adverse reactions that extravasation may cause necrosis; those with a double asterix - not stated in CPS; others have no monograph listed in the CPS):

References:
Burd, D., Santis, G. & Milward, T. (1985). Severe extravasation injury: An avoidable iatrogenic disaster? British Medical Journal, 290(6481), 1579-1560.

Cohan, R., Dunnick, N., Leder, R. & Baker, M. (1990). Extravasation of nonionic radiologic contrast media: Efficacy of conservative treatment. Radiology, 176(1), 65-67.
Cohan, R., Leder, R., Bolick, D., Herzberg, A. (1990). Extravascular extravasation of radiographic contrast media.

Effects of conventional and low-osmolar agents in the rat thigh. Investigative Radiology, 25(5), 504-510.

[back to top]

 

 

Page 6 of 7  Main Menu   <<Back   Next>>

Registered Nurses´ Association of Ontario