Subcutaneous
fluid administration
Introduction
This procedure involves the administration of a sterile
injectable fluid into the subcutaneous tissue. Fairly large amounts of fluid
may be introduced into the body in this way; solutions may include dextrose and
some electrolytes. Fluids administered subcutaneously are very well absorbed
systemically so sometimes remove the need for intravenous infusions.
Subcutaneous fluid administration is also referred to as hypodermoclysis,
(Ferry et al 1999).
Indications
Subcutaneous infusions, (SCIs) may be used to replace lost
body fluids and salts after haemorrhage, burns or diarrhoea and vomiting. In
addition hydration may be maintained in patients at risk from dehydration due to
factors such as an inability to swallow or reduced levels of consciousness.
Dehydration is associated with complications such as confusion, urinary tract
infection, chest infection and an increased risk of pressure sore formation so prevention is very important. The thickening of the blood in
dehydration may lead to an increased risk of thromboembolic disorders such as
stroke, deep venous thrombosis and myocardial infarction. Pyrexial patients
lose more fluids than those who are apyrexial so this should always be
replaced.
Solutions of amino acids may also be given by subcutaneous
infusions in patients who are unable to eat normally during a period of
illness. Analgesics such as morphine may be also be given by SCI, (Coyle and
Adelhardt 1996)
Advantages
SCIs are perhaps under used in care of the elderly as they
have the advantage of maintaining a healthy fluid and nutritional status
without the complications associated with intravenous therapy. Complications of
intravenous therapy include haemorrhage, extravasation, (tissuing), air
embolism, thrombosis, bacteraemia and septicaemia. SCIs require minimal skill
to set up and remove. Because the infusion rate is relatively slow
complications of over hydration such as pulmonary oedema are unlikely to occur,
(Abdulla and Keast 1997). Thoughtful siting will allow patients to retain
freedom of movement. Elderly patients
may be difficult to cannulate intravenously, in addition iv
and attempted iv cannulation will damage peripheral veins.
Potential
complications
Harmless localised oedema is the most common complication
but will always resolve when the infusion is slowed down or removed. The risk
of infection is minimised with good technique. Infusions should always include
saline to prevent the levels of salt in the blood dropping. Potassium in high
concentrations may cause local necrosis but it is safe to give up to 2 g of
Potassium Chloride per litre of solution, (Ferry et al 1999). The risk of damaging a blood vessel is slight
but if blood does appear in the tubing the infusion should be re - sited with a
new needle, any bleeding should be arrested with direct pressure. Pain is rare
and usually related to the needle penetrating underlying muscle. A correctly
sited needle will be able to move freely between the skin and the underling
muscle. Pain may also be caused if the flow rate is too high. While the likelihood of changes in plasma
electrolyte concentrations are less than with
intravenous infusions this aspect of care should still be considered.
Practical aspects
The chosen site should be cleaned using an alcohol
impregnated swab and the alcohol allowed time to dry. The area should be
swabbed in one direction only so bacteria are removed in the sebum and not
simply redistributed over the site. The butterfly cannula used may be a 19 or
21 gauge, this is connected onto the end of the giving set which is then
primed. The infusion fluid should also prime the cannula giving tubing and
needle. The needle is then inserted into the subcutaneous layer, normally at an
angle of about 45 degrees to the surface of the skin, (Farrand and Campbell
1996). In thinner patients it may be necessary to pinch up the area of skin
first, but if this is done the actual insertion site should not be touched. The
needle of the butterfly should be fully inserted. As the needle insertion site
is technically a wound it should be covered with a dressing, this will seal the
wound and stabilise the butterfly. A transparent dressing is needed as it is
important to observe the site for features of possible inflammation. The
infusion may then be started.
Strict use of asepsis is vital. The risk of local infection
should be minimised by changing the administration needle daily. Mansfield et
al (1998) recommended changing the site every 24 hours and the giving set at
least every 72 hours. The most common sites used are the abdomen or the chest,
usually below the breasts in women. The area over the scapular may also be
used.
The procedure should be appropriately documented with a note
taken of when cannula and giving sets need to be changed. The overall fluid
balance of the patient should also be recorded. A well hydrated patient will
produce at least 1500 mls of urine per day.
Infusion rates
Normally up to 1.5 L per day will be infused per site. Two sites
may be used to give a total of 3 L per day. As much as one litre over 8 hours
is tolerated well by most patients if required. Abdulla and Keast (1997)
advised an infusion rate of 125ml/hour. The practitioner has some latitude with
infusion rates depending on their assessment of the local and systemic
condition of the patient. The rate of absorption of administered fluid may be
increased by the addition of the enzyme hyaluronidase, but this is not
essential.
Conclusion
SCIs are a safe and effective way to treat and prevent
dehydration and so prevent complications. They may be used in hospitals or at
home and are often the kindest method for the patient and are less demanding on
staff and finances.
References
Abdulla A. Keast J.
Hypodermoclysis as a means of rehydration.
Nursing
Times. 93(29):54-5, 1997 Jul 16-22.
Coyle N. Adelhardt J. Cancer
patients and subcutaneous infusions.
American
Journal of Nursing.
96(3):61, 1996 Mar.
Farrand S.
British
Journal of Hospital Medicine. 55(11):690-2, 1996 Jun 5-18.
Ferry M. Dardaine V.
Constans T. Subcutaneous infusion
or hypodermoclysis: a practical approach. Journal of the
American Geriatrics Society.
47(1):93-5, 1999 Jan.