Question Answer
What are the trigger variables for VC/AC CMV? Pressure Time Flow
What are the limit variables for VC/AC CMV? volume flow
What are the targeted variables for VC/AC CMV? volume
What are the cycle variables for VC/AC CMV? Vol
What are the trigger variables for VC/SIMV? Time Volume Pressure
What are the limit variables for VC/SIMV? Volume
What are the limit variables for VC/SIMV? Volume
Question Answer
What type of pressure ventilation involves normal respirations, Chest cuirass, and iron lung? Negative pressure
5 examples of positive pressure ventilators are CMV, A/C, IMV, SIMV, CPAP
Positive pressure ventilators can be ____ vs ____ controlled pressure, volume
There is ____ and ____ modes available for PPV adaptive, dual
2 types of nonconventional ventilation HFOV (cpap with a wiggle), APRV (cpap with spontaneous breaths)
During spontaneous breathing when does pressure equalize? at end inspiration and end exhalation
How does PPV create transairway pressure? by increasing airway opening pressure above the alveolar pressure
PPV generate gas flow, therefore ____ ____, by producing a positive pressure gradient tidal volume
2 things to consider when using PPV alveolar/capillary filling occurs during active phase of inspiration which is usually neg pressure and under PPV, vascular flow can be impeded
Modes of PPV from the most support to the least support CMV, A/C, IMV, SIMV, CPAP
Advantages of volume controlled Ensures minimal VE
Disadvantages of volume controlled pressure variable:barotrauma/volutrauma possible, volume limited by high pressure alarm
Advantages of pressure limited less risk of barotrauma d/t set inspiratory pressure
Disadvantages of pressure controlled doesnt ensure VE; Vt variable
What 2 things are variable on pressure controlled vent volume(dependent on set pressure) and Flow
4 types of triggers Time, patient, pressure, flow
What is the control used to adjust ventilator sensory of patient inspiratory effort called sensitivity
What are the 2 types of sensitivity controls? pressure (ex:IPPB), and Flow
How does a perssure trigger work? ventilator senses a drop in pressure below the baseline, senses pt negative inspiratory effort
Pressure transducers are placed at these 3 locations proximal airway- at teh wye connector, internally where gas flow leaves the unit, and where exhaled gas leaves the unit
Which trigger type is more sensitive, pressure or flow? flow
How does a flow trigger work? when a pt initiates a breath base flow returning to the vent is reduced thus triggering inspiration
Describe Controlled Mandatory Ventilation Time triggered, machine breath, volume or pressure cycled
What does CMV control to equal VE? (Vt or Pressure) + RR=VE
What are the indications for CMV? Need to control VE completely; need to control chest expansion completely like with flail chest
Complications of CMV? pt is totally vent dependent, alarams are essential, unable to assess weaning and seizures interrupt delivery of breath
Time/breath/cycle for A/C vent Patient or Time triggered, machine driven, volume cycled
Indications for A/C mode full ventilatory support, need to support high VE with low O2 consumption, sedation after intubation
Advantages of A/C mode Decrease WOB(pt trigger only), pt controls RR therefore VE (resp compensation, normalize CO2)
Complications of A/C mode hyperventilation(resp alkalosis), pain/anxiety/CNS disease, Biots or Cheyne stokes respirations
Describe IMV mode first widely used mode that allowed partial ventilatory support, facilitates weaning, increase muscle strength. Not widely used today
Complications of IMV breath stacking(spont effort immediately followed by mechanical breath) which leads to increased PIP, barotrauma, cardiac compromise
What is baotrauma/volutrauma? lung injury that occurs from hyperinflation of alveoli past rupture point (PIP>50, Pplat>35)
SIMV triggers/type of breaths/cycling mechanism trigger:mandatory(time or pt triggered/assisted), Type:mechanical, assisted, or spontaneous; Cycle:mechanical/assisted(preset Vt or pressure), Spontaneous:pt determines Volume
What is the synchronization window? time interval just prior to time triggering in which the ventilator is responsive to the patient’s spontaneous breath
Indications for SIMV parital vent support, pt can actively participate in VE
If the set rate is high(8-12) in SIMV mode can provide total support (SIMV with no spontaneous rate is the same as A/C)
Setting the rate low (<8) in SIMV: facilitates weaning, strengthens respiratory muscles, decreases mean airway pressure making spont breaths have a lower peak pressure than mandatory
Complications of SIMV: low rate can increase WOB causing muscle fatigue/failure
What mode of PPV has a positive baseline pressure continuously applied to the circuit and airway during both I and E? CPAP
in this mode of PPV the ventilator delivers a time triggerd breath and allows patient to breath at own Vt bw mechanical breaths. IMV
In this mode of PPV the ventilator delivers a set Vt or pressure at a time triggered rate but the patient can trigger a mechanical breath above preset rate A/C
In this mode of ventilation patient can not trigger mechanical or spontaneous breath so there is no negative deflection on graphics. The pt must be sedated or paralyzed.Not commonly used CMV
In order for this mode of PPV to be used the pt must be spontaneously breathing, have adequate lung function to maintain normal PaCO2, and are not at risk for hypoventilation CPAP
3 things pressure support does? augments spontaneous Vt, Decreases spontaneous RR, and reduces patient WOB, Raw
How does pressure support decrease spontaneous RR? increased volume decreases need for high RR to achieve required VE, decreases deadspace ventilation
Desired RR is less than __ 25
What is Vt dependent upon with Pressure support mode? set inspiratory pressure, lung compliance, and airway resistance
What makes flow variable in PS? dependent upon flow needed to maintain pressure plateau
PS:trigger, breath, cycle patient triggered, spontaneous, pressure limited, flow cycled
CPAP with PS is BiPap
CPAP with no PS is CPAP
Management of PS begin with 5-10cwp, increase in increments of 3-5cwp
Titrate PS according to what 3 things? Spont Vt 5-7ml/kg IBW, RR less than 25, Decrease in WOB
This is not a “stand alone” mode PEEP
Effects if PEEP recruit alveoli, increase FRC(oxygenation), increase alveolar surface area(gas diffusion), increase compliance, prevent VILI
Complications of PEEP cardiac compromise, increase intrathoracic pressure, decrease venous return, decrease CO and BP
Indications for PEEP refratory hypoxemia and 5cwp is considered physiologic to replace glottic closure
PEEP mgmt 5cwp=physiologic, increase in increments of 3-5cwp while watching BP, decrease to previous level or zero for low BP, treat low BP with vol expansion or vasopressors then increase PEEP again while observing BP
What is compliance volume change per unit pressure
Inverse ratio ventilation is ___ controlled pressure
Long I, Short E causes what? air trapping, auto PEEP and prevents alveolar collapse
Auto-PEEP= increased oxygenation, peep effects, increased FRC, PaO2, and surface area
How does IRV prevent alveolar collapse? critical opening pressure reduced, pressure needed for ventilation is less, improves ventilation
Complications of IRV barotrauma, requires paralysis sedation, cardiovascular compromise similar to PEEP effect
Mandatory minute ventilation activates when a pts spont breathing is less than minimum set VE, ventilator increases ventilation
The method of increased ventilation with MMV varies upon what? ventilator model(some icrease RR, some Vt, and some PSV)
What should VE be set to achieve? satisfactory PaCO2
Advantages of MMV promotes spont breathing, minimal support but protects against hypoventilation and resp acidosis, permits weaning but compensates for apnea
Disadvantages/complications of MmV doesnt protect against RSB(deadspace breathing), High RR with low Vt = patient breathing above VE(MMV remains inactive but PaCO2 increases, resp acidosis)
Describe Pressure control(PCP Vt variabl, Inspiration begins at preset pressure, Plat is created and maintained for preset I-time, Flow is variable dependent on flow required to maintain pressure plat
Pressure control generates a ____ flow to increase the airway pressure to a preset pressure limit high
When is inspiration terminated in Pressure Control when the preset I-Time is reached
Indications fro PC low lung compliance-high PIP during volume ventilation (PIP > 50, Plat>35); ARDS-ARDS net protocol
Advantages of PC PIP is reduced while maintaining adequate oxygenation and ventilation, reduced risk of barotraumas
Management of PC Pip is set to achieve a goal Vt, unless pt is allowed to become hypercapnic in the interest of limiting PIP; VT and VE must be carefully monitored
What is APRV? airway pressure release ventilation
What happens during inspiration of APRV applie positive airway pressure to augment spont breathing (High CPAP level, reduces WOB, Increases MAP to increase O2, allow spont inspiration at any point during the breath-elevated pressure delivery)
What happens during exhalation with APRV positive pressure is periodically released to allow exhalation (brief 1-2 seconds), decreases FRC and allows for exhalation and release of CO2
APRV is inappropriate for what kind of patients? those at risk for an inadequate spontaneous RR
APRV can resemble IRV when expiratory pressure release time is less than spontaneous effort
Why is APRV beneficial alternative to IRV does not require paralytics
APRV: trigger/limit/cycle time triggered but pt is allowed to breathe spontaneously at any time; mandatory and spont pressure limited; time cycled d/t preset I-time
Describe HFOV reduces risk of lung destruction by keeping alveoli open at constant pressure, oscillates very rapidly (high RR, Hertz, small volumes), early intervention is key!
Managing oxygenation with HFOV Mean airway pressure, FiO2, alveolar recruitment
Managing ventilation with HFOV amplitude-delta “P”, Hertz, % I time, cuff deflation, permissive hypercapnia
Amplitude delta “P” change in stroke volume, force delivered by piston by setting power, CWF-chest wiggle factor
Hertz (1 hertz=60rr), set at 3-6 Hz, decrease rate to eliminate CO2
% I time determines delivery of Paw
Patient care HFOV Sx PRN, humidity circuit, bronchodilator, sedate or paralyze, pronation, fluid bolus prn, vasopressors, bronchoscopy
Assesment HFOV Hr, SpO2, BP, CWF, Auscultate, CXR, ABG