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Monitoring during mechanical ventilation: INDIRECT CALORIMETRY (4)

The breath-by-breath calorimeter analyzes FiO2, fractional concentration of oxygen in expired gas (F E O2), F E CO2 and VT with each breath. This obviates the need for a mixing chamber. The system uses the same gas analysis and volume measuring devices as the open circuit calorimeter, and these systems generally have the same limitations as open circuit systems.
In patients with a pulmonary artery catheter, V O2 can be calculated from CaO2, CvO2 and cardiac output as follows:
Monitoring during mechnical
This method can only be used if a thermodilution pulmonary artery catheter is in place. Continuous 24 h indirect calorimetry will ideally produce the best estimate of resting energy expenditure (REE). However, 24 h measurements of V O2 and V CO2 are not practical unless the metabolic monitor is an integral part of the ventilator system (eg, Puritan Bennett 7250, Puritan Bennett). For many critically ill patients, it is impossible to obtain measurements for longer than 15 to 30 mins more than once every several days. It is important, however, to recognize that shorter and less frequent measurements less reliably estimate REE. When performing indirect calorimetry, the patient should be resting, undisturbed, motionless, supine and aware of the surroundings (unless comatose). The patient should either be on continuous nutritional support or fasting for several hours before the measurement. Before indirect calorimetry is performed, there should have been no changes in ventilation for at least 90 mins, no changes that affect V O2 for at least 60 mins (change in fever, motion, etc) and stable hemodynamics for at least 2 h. The validity of measurements should be assessed by direct observation rather than relying on a ‘steady state’ indicator of the calorimeter. A truly reliable pharmacy you can always rely upon and where you can always purchase cialis online pharmacy without any need for a prescription or seeing a doctor? This is the thing you wanted, so don’t hesitate now that you have it available!

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