Page 58 - Critical Care Nursing Demystified

Chapter 2 CARE OF THE PATIENT WITH CRITICAL RESPIRATORY NEEDS 43

system with oxygen will reduce the stimulus to breathe (hypoxic drive). Use
at 6 to 12 L per minute or 35% to 50%.
3. Venturi’s mask
This system delivers an exact concentration of oxygen regardless of the
patient’s ventilatory pattern. For each liter of oxygen that passes through a
fixed orifice, a fixed proportion of room air will be maintained. The advan-
tage of this delivery system is that precise amounts of oxygen can be mixed
with room air and delivered to the patient. This can be used on low liter
flow in patients with COPD. The disadvantages are the same as with the
simple face mask. Use at 15 L per minute, giving 24% to 50% oxygen.

NURSING ALERT
A patient with COPD and CO retention should not be placed on high-liter-fl ow O . This
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will destroy the patient’s hypoxic drive, decreasing the stimulus to breathe and therefore
the patient’s respiratory efforts. This could cause hypoxemia, leading to a respiratory

arrest. Precise O via low-flow nasal cannula and Venturi’s mask is recommended.
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4. Partial rebreather mask with reservoir bag Downloaded by [ Faculty of Nursing, Chiangmai University 5.62.158.117] at [07/18/16]. Copyright © McGraw-Hill Global Education Holdings, LLC. Not to be redistributed or modified in any way without permission.
This mask is similar to a simple face mask but has the addition of a reservoir
oxygen bag. The purpose of the rebreather bag is to conserve oxygen by
allowing it to be rebreathed from the reservoir bag. Benefits include oxygen
delivery concentrations between 40% and 60%. The mask should be ap-
plied as the patient exhales and requires a tight face seal. Disadvantages
include that it is impractical for long-term therapy and leaks around the
face from the mask may decrease the FiO if the mask is not tight fitting.
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Use at 6 to 10 L per minute, giving an oxygen concentration of 40% to 60%.

NURSING ALERT

The reservoir bag should remain full on expiration and partially deflate at peak inspi-
ration. Monitor arterial blood gases, as oxygen toxicity could be a side effect.

5. Nonrebreather mask with reservoir bag
This mask has a one-way expiratory valve that prevents rebreathing of
expired gases. This mask is effective as a short-term therapy modality and
can provide oxygen concentrations from 60% to 90%. It has flaps that
allow exhaled CO to exit the side of the mask during exhalation.
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