chapter 7 pb Flashcards
How do you determine the FiO2 for a patient with a low PaO2?
FiO2= (desired Pa02 x known FIO2) / PaO2 known
Your patient is on FIO2 of 30% and ABG’s reveal is PaO2 is 73. You want his PaO2 to be 100. What do you change their FIO2?
Change it to 39%
If a baseline ABG is not available, it is advisable to select how much FIO2 for patients with presumed severe hypoxemia
high initial FIO2 setting ≥0.50.
Flow triggering is set in a range of
1 to 10 L/min below the base flow
Many clinicians prefer using flow triggering because it provides a slightly faster response time compared with pressure triggering for what two main reasons?
First, the exhalation valve does not have to close during flow triggering.
Second, there is a flow of gas in the circuit during exhalation when flow triggering is selected. This flow requires that the inspiratory flow control valve remains open. This provides almost immediate flow on demand for the patient
DEFINITION Positive end-expiratory pressure; airway pressure greater than zero at the end of exhalation
PEEP
DEFINITION the level of PEEP set by the operator on the ventilator
Extrinsic PEEP (PEEPe)
DEFINITION the amount of pressure in the lungs at the end of exhalation when expiration is incomplete (i.e., expiratory flow is still occurring) and no PEEPe is present
Auto-PEEP (Intrinsic PEEP, or PEEPi)
What are three situations Auto-Peep occurs?
(1) strong active expiration, often with normal or even with low lung volumes (e.g., Valsalva maneuver);
(2) high minute ventilation (>20 L/min), where expiratory time (TE) is too short to allow exhalation to functional residual capacity;
(3) expiratory flow limitation due to increased airway resistance, as may occur in patients with chronic obstructive pulmonary disease on mechanical ventilation or with small endotracheal tubes or obstructed (clogged) expiratory filters
Adding PEEP to a patient with Auto-PEEP would be ineffective if
auto-PEEP is a result of a high minute ventilation (VE) and if there is insufficient expiratory time
DEFINITION A spontaneously breathing individual’s inspired air is typically conditioned down to the fourth or fifth generation of subsegmental bronchi.
isothermic saturation boundary
The humidification system used during mechanical ventilation should provide at least _____ of absolute humidity at a temperature range of about 31° to 35° C for all available flows up to Ve a of 20 to 30 L/min
30 mg H2O/L
Refilling heated humidifiers is best accomplished by using what kind of system?
closed-feed system
A 60-year-old man with COPD is receiving PSV. He appears to be having difficulty triggering the breaths. Auto-PEEP is measured at +8 cm H2O and no PEEPE is being used. Sensitivity is set at −1 cm H2O. How much of an effort (in centimeters H2O) must the patient generate to trigger a breath?
- 9 cm H20
How does condensate accumulates in the circuit?
Whenever the temperature in the patient circuit is less than the temperature of the gas leaving the humidifier,
What is another name for condensate?
rain-out
When room temperature becomes cooler, what happens?
More rain-out in the tubing.
What can help reduce rain-out?
Using heated wire circuits on the inspiratory and expiratory lines
If the temperature of the gas in the patient circuit is higher than the humidifier, what happens?
the relative humidity in the circuit decreases, and drying of secretions can occur
What is a way to assess a humidity deficit?
Assess the patients secretions. Thick secretions
Without a heated wire circuit, the humidifier may need to be heated to as much as ?° C for the gas temperature to approximate body temperature (37° C) by the time it reaches the patient’s upper airway.
50° C
Assessment for Secretion Thickness
Following suctioning, the suction catheter is clear of secretions.
Thin
Assessment for Secretion Thickness
Secretions adhere to sides of suction catheter after suctioning but are easily removed when water is aspirated through the catheter.
Moderate
Assessment for Secretion Thickness
Rinsing the catheter with water following suctioning does not clear secretions that adhere to the suction catheter.
Thick
