Total parenteral nutrition (TPN)

Total Parenteral Nutrition is defined as the provision of all nutritional requirements, without the use of gastrointestinal tract. It is employed when there is intestinal failure i.e. 'A reduction in the functioning gut mass below the minimal necessary for adequate digestion and absorption of nutrients.'

Indications for total parenteral nutrition

1- Absolute Indications

   Proximal entercutaneous fistulae

2- Relative Indications

  Moderate or severe malnutrition.

  Severe Inflammatory bowel disease.

  Severe Pancreatitis

  Prolonged ileus

  Abdominal sepsis.

  Major trauma and burns

  Massive intestinal resection (particularly if <100 cm of small bowel remians)

Contraindications for TPN

  Congestive cardiac failure

  blood dyscariasis

  uncontrolled diabetis mellitus

  fat metabolism disturbance

  liver failure

Infraclavicular subclavian line

Meshed split-skin graft

Split thickness graft (Thiersch graft) consists of epidermis and part of dermis. The graft is taken with a special knife which cotrols the skin thickness. This may be carried out with either free hand knife (Humbeys knife) or with a powered instrument called dermatome. The split thickness graft is approximately 0.25 mm thick. The usual donar sites are the anterior aspects of the thighs, arms and buttocks ; the donar sites heal from the skin appendages (hair folllicles, sweat glands) in 10 to 15 days. Sometimes, the donar site may not be adequate to cover the defect. In these situations, the graft is passed through a mesher who creates multiple longitudnal holes in the graft. There are two advantages of messhing the graft :

1- It increases the surface area of the graft up to two times.

2- Any haematoma or seroma gets removed through these holes. 

Partial thickness skin grafts, if kept moist, can be stored at 4 degrees centigrades for 3-4 weeks.

Phases of healing

Healing is a natural process and it occurs in three phases

1) Inflammatory Phase (also called reactive phase):

It is the immediate reaction by tissues with formation of fibrin clot mesh with platlets, with release of coagulation factors and cytokines, initiating healing. It limits amount of damage and prevents further injury. This phase lasts for 2 to 5 days.

2) Proliferative Phase (regenerative or reparative phase):

The combined processes of epithelization, fibroplasia and angiogenesis occur in order to replace dead and missing tissues. This phase lasts for 2 days to 3 weeks.

3) Maturation Phase (remodeling phase):

The new matrix contracts with cross linkage of collagen and the scar tissue matures, with loss of edema. This phase may take 3 weeks to 2 years to complete.

The phases of healing. (a) Early inflammatory phase with platelet-enriched blood clot and dilated vessels. (b) Late inflamma- tory phase with increased vascularity and increase in polymorpho-nuclear leukocytes and lymphocytes (round cells). (c) Proliferative phase with capillary buds and fibroblasts. (d) Mature contracted scar.