Ventilator controls - pressure Controller
the ventilator maintains the same pressure waveform at the mouth regardless of changes in the lungs
Ventilator controls - flow controller
Ventilator volume delivery and volume waveform remain constant and are not affected by changes in the lung. Flow is measured
Ventilator controls - volume controller
ventilator volume delivery and volume waveform remain constant and are not affected by changes in the lung. Volume is measured
Ventilator controls - time controller
pressure, volume, and flow curves can be changed as lung changes. Time remain constant
Four phases of breath
Change from exhalation to inspiration, inspiration, change from inspiration to exhalation, exhalation
define continuous gas flow
gas flow provide at the end of exhalation because airway resistance is low. Many new ICU ventilators provide this.
define expiratory hold
a pause at the end of exhalation because it is measuring the pressure associated with air trapping (auto PEEP)
define expiratory retard
resistance on the expiratory side because of ventilator circuits, expiratory valves, and bacterial filters
Continuous positive airway pressure that helps improve oxygenation to a spontaneous breathing patient.
Positive pressure that remains in the airway at the end of exhalation . Improves oxygenation.
Evaluation of a patient in respiratory distress involves what three basic assessments?
patient's level of consciousness, color, vital signs
Evaluation of patient's LOC ask what type of questions?
are they awake? can they be aroused? what extent of consciousness are they?
Evaluation of color , appearance, and texture involve looking at what three variables?
naie beds, pale, level of diaphorisis
define respiratory distress
absence or insufficient respiratory activity to maintain adequate oxygen uptake and carbon dioxide clearance AND the inability to maintain PO2, PCO2, and PH.
List six reasons hypoxic failure would happen
v/q mismatching, diffusion defects, right to left shunting, alveolar hypoventilation, aging, inadequate inspired oxygen
Acute hypoxic failure is indicative of
a life threatening situation that may also be vital organ threatening to tissues
If acute hypoxic failure is occurring with hypercapnia,and WOB how do you treat?
Mechanical ventilation but it is a last resort
What can hypercapnia be caused by?
CNS disorders, neuromuscular disorders, any disorder that increases WOB
list a early indicator of hypercapnia
PaCO2 levels are elevated unless receiving supplemental oxygen
What conditions can hypercapnia lead to, if not treated correctly
CO2 narcosis, cerebral depression, coma, death
CNS disorders reduce the drive to breath and can be caused by
drug over dose, trauma, hypothyroidism, CSA
List some conditions that may effect muscle function
electrolyte imbalance, malnutrition, PN disorders, atrophy, fatigue, COPD
List some problems that occur because of an increase in WOB
pluera-occupying lesions, chest wall deformities, increased raw, lung tissue involvement, pulmonary vascular problems, post-op, hyperinflation
What two ventilator mechanics measurements are used most often to assess the condition of respiratory muscles?
What ventilator parameter is used most often to with acute asthma?
FEV1 is also used but not as much
What ventilator parameters are used to assess the need for invasive ventilation AND also indicators for discontinuing ventilation?
MIP, MEP, VC, Vt, F, FEV1, PEFR
What are normal and critical values of MIP (maximum inspiratory pressure)
N: -100 to -50
C: -20 to 0
List some physiological measurements (values) that are good indicators of oxygenation failure
PaO2 (less than 70 with a SPO2 of 90 on a FIO2 of 60% or less indicates hypoxic failure), SpO2, P [A-a]O2, PaO2/PAO2, P to F ratio
What are the values present when ventilation failure is imminent?
PaCO2 of 50-55 and rising
PH of 7.25 or less
What are some ethical considerations that we must ask ourselves before intubation?
Do they really want this? Do they have a living will? What is their advance directive?
What is a contraindication of mechanical ventilation?
If it's use is medically pointless, futile and NO chance exists that this treatment would extend this person's quality of life in a meaningful way.
Explain 'elastic recoil pressure' 's place in the motion equation
The volume of air in the lungs depends on this pressure which is the result of alveolar tension on the volume within the alveoli
List two other names for pressure-limited ventilation
pressure-targeted ventilation, pressure controlled
What happens in most ICU ventilators if the pressure limit is reached?
1. Inspiration ends, tidal volume reduced
2. An alarm sounds
Which ventilator uses a brief negative pressure at the beginning of the expiratory phase?
On a pressure-time wave form, the curve during the expiratory phase does not return to the baseline rapidly, like it should, but eventually makes it. What could be the problem?
an obstruction in the expiratory line
Inspiratory flow ends and exhalation begins when a preset time has elapsed. This is called?
The pressure-time waveform does not change during inspiration but the volume-time waveform changes with lung characteristics. This is called?
Indications of NPPV
RR of 25 or less
PH of 7.30-.7.35, 45-60 mm Hg
Using accessory muscles (mod-severe dyspnea)
Although manipulation of a mechanical ventilator can be helpful in reducing intracranial pressure, this procedure has NOT been shown to improve long-term outcomes. T or F.