Nutritional Therapy: Patient Receiving Positive Pressure Ventilation
PPV and the hypermetabolism associated with critical illness can contribute to inadequate
Patients likely to be without food for 3 to 5 days should have a nutritional program
Poor nutrition and the disuse of respiratory muscles contribute to decreased respiratory
Inadequate nutrition can delay weaning, decrease resistance to infection, and decrease the
speed of recovery.
Enteral feeding via a small-bore feeding tube is the preferred method to meet caloric
needs of ventilated patients.
Evidence-based guidelines regarding verification of feeding tube placement include: (1)
x-ray confirmation before initial use, (2) marking and ongoing assessment of the tube’s
exit site, and (3) ongoing review of routine x-rays and aspirate.
A concern regarding the nutritional support of patients receiving PPV is the carbohydrate
content of the diet.
o Metabolism of carbohydrates may contribute to an increase in serum CO level2
resulting in a higher required minute ventilation and an increase in WOB.
o Limiting carbohydrate content in the diet may lower CO pro2uction.
o The dietitian should be consulted to determine the caloric and nutrient needs of these
Weaning from Positive Pressure Ventilation and Extubation
Weaning is the process of reducing ventilator support and resuming spontaneous
The weaning process differs for patients requiring short-term ventilation (up to 3 days)
versus long-term ventilation (more than 3 days).
o Patients requiring short-term ventilation (e.g., after cardiac surgery) will
experience a linear weaning process.
o Patients requiring prolonged PPV will experience a weaning process that consists
of peaks and valleys.
Weaning can be viewed as consisting of three phases. The preweaning, or assessment,
phase determines the patient’s ability to breathe spontaneously.
Weaning assessment parameters include criteria to assess muscle strength
and endurance, and minute ventilation and rapid shallow