Extra Topic 5.3 -- TPN

Question 1

What are the complications of TPN?

Answer 1

The complications of TPN include –

• metabolic disturbances,
• those secondary to catheter insertion,
• liver failure (fatty liver),
• venous thrombosis (secondary to fat infusion), and
• cholecystitis (secondary to an inactive gastrointestinal system).

Complications associated with catheter placement include –

infection/sepsis, pneumothorax, and accidental arterial puncture.

The various metabolic disturbances associated with TPN include –

• hypokalemia,
• hypophosphatemia,
• hypomagnesemia,
• hypo/hyperglycemia,
• acidosis/alkalosis,
• hypo/hypercalcemia, and
• hypercarbia.

Question 2

Would you have any additional concerns if your patient receiving TPN was on a ventilator and had chronic obstructive pulmonary disease (COPD)?

Answer 2

Given that COPD patients are often CO2 retainers, I would be concerned that excessive carbohydrate delivery with TPN may lead to increases in CO2, creating a metabolic demand for O2 that cannot be met.

I would, therefore, consider decreasing the carbohydrate load and increasing the lipid component (lower the respiratory quotient) to prevent further increases in CO2.

Question 3

Why might you have difficulty weaning someone off the ventilator when they have been receiving TPN?

Answer 3

One potential complication of TPN is hypophosphatemia,

which may result in muscle weakness and subsequent difficulty in weaning a patient from the ventilator.