3210 Advanced mechanical ventilation
What has a descending ramp shown to do?
1. *reduce peak pressure lowering risk of barotrauma 2. reduce inspiratory work 3. reduce VD/VT 4. reduce P(A-a)O2 *All done while not affecting hemodynamic values
What are the catabolic stressors that cause changes in values of renal failure to double?
1. Burns 2. severe trauma 3. rhabdomyolysis 4. sepsis 5. starvation
What are the examples of continuous spontaneous breath modes?
1. CPAP 2. BIPAP 3. PSV 4. automatic tube compensation ATC 5. proportional assist compensation PAV 6. neutrally assisted ventilatory assist NAVA
Acute hypoventilation or apnea does not cause?... and what prevents academia?
1. Hypercapnea 2. MMV
What are the characteristics of rectangle/square/constant?
1. MAP is the highest with this waveform 2. volume-targeted breaths with a constant inspiratory flow produce this waveform
The examples of scalars displayed during the mechanical ventilation include?
1. P vs. T 2. F vs. T: straight line parallel with x-axis 3. V vs. T:used to asses auto-PEEP
During CMV, when the mode is poorly tolerated and spontaneous triggering is counterproductive to the goals set for the patient, what can be done, and why does it help?
1. Patient can be put on sedation or paralysis meds -the agents minimize patient effort and normalize WOB
What are the variables that determine the level of support achieved in ATC?
1. Patient effort 2. resistance of the ET Tube
What parameters are set with VSV?
1. VT 2. Max Peak Pressure 3. Flow
What are some means of identifying leaks?
1. Volume-Time scalar 2. Pressure-volume scalar 3. flow-volume scalar
What are the three basic breath delivery techniques or modes?
1. continuous mandatory ventilation (CMV) 2. synchronized intermittent mechanical ventilation (SIMV) 3. spontaneous modes (CSV)
What are the ICP monitoring categories?
1. fluid filled systems with external transducers 2. solid state systems with miniature pressure transducers
Using PC-IRV.... In ARDS/ALI patients, more time is allotted for inspiration and less for expiration causeing what?....>1:1 ratio
1. intrinsic PEEP 2. maintenance of numerous alveoli open up - short time constants improving arterial oxygenation
What can Raw be increased by?
1. mucosal edema 2. bronchospasm 3. increased secretion in airway 4. use of sm. ET tube
What suggests hepatic inflammation?
Elevate levels of aspartate and alanine aminotransferase
When an VSV be used?
For patients who are ready to be weaned from the vent and can breathe spontaneously.
GCS 9-13 indicates?
ICU admission
GCS 8 or < indicates?
ICU admission and ICP monitoring
The most common use of PC-CMV?
In patients with ARDS whose oxygenation status has failed to improve with the application of VC-CMV.
What is significant about how volume support ventilation (VSV) works?
It is a pressure breath that is patient triggered, volume targeted (pressure limited), flow cycled (breaths).
What mode may offer greater control of a patients PaCO2 than SIMV?
Mandatory Minute Ventilation (MMV)
What are the mean airway pressure values during VC-CMV?
Mean airway pressures are typically high.
In APRV, after a period of high PEEP, what happens?
There are brief approx. 0.5 sec (short), (intermittent) decreases in airway pressure to the low PEEP level (lower airway pressure) -gives a VT for the mode
Volume Support Ventilation (VSV) is similar to PSV how?
Ventilator triggering and cycling are triggered by the patient.
When is pressure controlled intermittent mandatory ventilation indicated?
When preservation of the pts spontaneous efforts are important and patient-ventilatory synchrony is a concern.
Acute hypoventilation becomes less of a concern when?
When sedatives, narcotics, or tranquilizers are administered.
In VC-CMV, what causes higher peak airway pressure increases?
a decrease in lung compliance or increase in resistance.
What would a pressure-volume loop look like with overinflation?
a duckbill or a beak
In the volume-pressure loop, what indicates increased WOB/inadequate sensitivity for pt triggering?
a fish tail at the base
What is the term loop used to describe?
a graph of two variables plotted on the x and y coordinates, such as *Pressure-Volume and *Flow-Volume loops
In VC-CMV, what is caused when there is a leak in the system?
a loss of volume from preset volume to actual delivered volume.
A pressure volume loop signifies what if its above or below the line?
above: increased lung compliance below: decreased lung compliance
What does loss of consciousness over days to weeks suggest?
abscess, tumor, or subdural hematoma
During weaning in PSV, a gradual reduction in support does what?
augments patients spontaneous VT.
On a flow vs. time scalar, what does it mean when expiratory flow does not return to zero?
auto-peep/air trapping
Why is CPAP considered to not provide ventilation?
b/c the airway pressure does not change
Why would PC-CMV be touted as superior to VC?
because it results in lower peak airway pressure, also helping to decrease airway and alveolar pressures
What does the ventilator do in PAV (proportional assist ventilation)?
deliver a pressure assist in proportion to the patients desired VT (volume assist) and to the patients instantaneous inspired flow (flow assist)
Whats the livers fx, and what are the routine indications for liver fx testing?
detoxifies wastes from metabolism and digestion and process poisons a) abdominal pain b)jaundice c)unexplained fever d)nausea e)malaise f)failure to thrive g)weight loss h)leukocytosis
Increased resistance in pts airway is noted by a large difference in What? and what kind of scalar?
difference in the PIP and Pplat on a pressure vs. time scalar
Whats polyguria?
excessive urination >3L/day
What does a leak look like on a volume-pressure scalar?
expiration volume does not return to zero
Volume-controlled intermittent mandatory ventilation is advocated for what type of patients?
for patients with relatively normal lung function recovering from sedation or rapidly reversing respiratory failure.
Whats cheyne stokes breathing?
hyperpnea alternates with episodes of apnea
In a flow vs. time waveform, improvement after a breathing tx would display as what?
improved PEF and shorter E-time
What does CPAP do?
increases alveolar pressure and maintains alveoli open
In VC-CMV, what causes patient ventilator asynchrony?
insufficient flow and improper pressure trigger settings (asynchrony)
Normal gag reflex implies?
intact 9th and 10th cranial nerve
What does normal corneal response imply?
intact ipsilateral 5th cranial nerver, central pons, and bilateral 7th cranial nerve
What does normal eye movement require?
intact pontomedullary-midbrain connection
What is significant about pressure support ventilation?
it is patient triggered, pressure limited, and flow cycled
What is a definitive sign of CNS dysfunction?
loss of moter fx and/or sensation in extremities *looking for bilateral symmetry
Whats oliguria?
low urine output <0.4L/day
What is significant about intermittent mandatory ventilation (IMV)?
mandatory breaths are delivered at a set rate, but in between mandatory breaths the patient can breath spontaneously at his or her own VT and rate.
Proportional assist ventilation is based on what?
mechanics of the total respiratory system and restrictive properties of the artificial airway.
What are spontaneous modes?
modes in which all breaths are initiated and ended by the patient.
In VC-CMV, because the ventilator is doing most of the work, what can occur?
muscular atrophy -typically if the patient is to not be weaned off the vent
GCS 13-15 indicates?
non-ICU observation
During CPAP, what does VT depend on?
patient effort and lung mechanics
What is PC-IRV?
pressure controlled ventilation with an I:E ratio greater than 1:1
PERRL?
pupils, equal, round, reactive to light
Whats anuria?
scant or no urine output <.05L/day
Whats ataxic breathing a marker for?
severe brainstem dysfunction
In intermittent mandatory ventilation (IMV), what does it allow or require the pt to sustain?
some amount of WOB
What is the primary goal of VC-CMV?
to achieve a VE that matches the pts metabolic needs
What reflects malnutrition?
values <2.2g/dL
What is the most common use of VC-CMV?
ventilating patients in the immediate post operative period.
When is volume controlled continuous mandatory ventilation (VC-CMV) indicated?
when a precise minute ventilation (ventilatory pattern) or blood gas parameter is essential for pt care
Normal BUN?
7-21mg/dL
Volume assured pressure support (VAPS) is?
-A dual controlled mode. -both VCV and PCV
Normal creatinine?
.6-1.2mg/dL
What does adaptive support ventilation monitor to ensure an acceptable VE?
1. pressure 2. flow 3. expiratory time 4. compliance 5. resistance (patient effort) 6. time constants
What are the 6 basic curves (waveforms)?
1. rectangular/square/constant 2. descending/descelerating ramp 3. ascending/accelerating ramp 4. sinusoidal/sine wave 5. rising exponential 6. decaying exponential
What are the characteristics of a descending/descelerating ramp?
1. results in low peak inspiratory pressures 2. in PCV, used to reduce the risk of barotrauma *ascending: highest peak pressure
What 2 factors contribute to the fact that during PPV, the volume of gas delivered is always less than the amount expelled?
1. the expansion of the ventilatory circuit 2. the compression of gas under pressure
What is the goal of pressure controlled ventilation and what varies?
1. to maintain adequate minute ventilation (VE) 2. volume and flow vary
What is the purpose of ventilator graphics?
1. to monitor fx 2. evaluate the pts response to the ventilator 3. to help the clinician adjust ventilator settings
PSV is used for what 3 basic function?
1. to overcome WOB in spontaneously breathing patients 2. reduce WOB in CPAP patients 3. To provide full ventilatory support in patients with assist mode, in which every breath is a pressure supported breath.
What is the primary variable to be controlled in value controlled ventilation and what varies?
1.VE (minute ventilation) 2. pressure varies
What are the parts of the neurological exam?
1.mental status 2.pupillary response 3.eye movement 4.corneal response 5.gag reflex 6. RR and pattern 7.motor evaluation 8.sensory evaluation *and history of pt
Whats mean ICP?
10-15mmHg
What ICP level causes compression of the capillary bed compromising microcirculation?
15-20mmHg
What ICP level impedes venous drainage and edema develops in uninjured tissue?
30-50mmHg
What ICP level makes cerebral perfusion incapable of being maintained?
40-50mmHg
During APRV, what can a pt do?
A patient can breathe spontaneously with high PEEP (elevated airway pressure) -this makes it more comfortable for the pt.
What can MMV provide?
A smooth transition from mechanical ventilatory support to spontaneous ventilation in patients recovering from drug OD or anesthesia.
Another name for continuous mandatory ventilation (CMV)?
Assist control
What indicates acute renal failure?
BUN increase of 10-15mg/dL per day creatinine increase of 1-25mg/dL per day
What does neutrally adjusted ventilatory assist (NAVA) respond to?
Changes in the diaphragmatic EMG activity.
Of all the classic modes, how is PSV different?
PSV exerts the least control over the patients ventilatory pattern, as a result should improve patient-ventilator synchrony.
How is a breath supported in VAPS?
Pressure supported when the delivered VT is greater than the preset VT.
what scalar can indicate inadequate flow and what does it look like?
Pressure vs. Time scalar a dip in the inspiratory section
What are the early signs of abnormal mental status?
Pt inability to follow a conversation or complex commands - subtle changes are often early signs of CNS dysfunction
In VAPS, when a set volume is not reached, what happens?
The flow continues at a constant rate until the desired volume is achieved.
What happens in pressure regulated volume control (PRVC)?
The inspiratory VT is compared to the preset target VT, and the inspiratory pressure on the next breath is adjusted up or down to attempt to meet the target volume.
What is the term scalar used to specify?
The waveforms for pressure, flow, and volume that are graphed relative to TIME.
