Mechanical Ventilation Flashcards
indications for intubation and mechanical ventilation
- increasing fatigue/WOB
- hemodynamic instability
- decreased LOC (stroke, TBI, seizures, OD)
- airway protection
- surgery/procedural
- resp failure
what does intubation involve the use of?
sedation, analgesia, NMBA (but not always)
most common route of intubation
orotracheal
nursing responsibilities with intubation
- prep and admin meds (RSI)
- monitor and treat hemodynamics
- document
- post intubation ax and care (ETT secured by RT and connected to vent, check placement - ETCO2)
- auscultate epigastric area and lung fields (insert NG/OG, confirm placement, sedation)
the seven P’s of RSI
1) preparation - RT prepares airway management. RN preps med, bed, position, good IV access
2) preoxygenation - BVM
3) pretreatment - analgesia, sedation, rescue meds
4) paralysis with induction - immediately after pre treatment
5) positioning - pt supine and flat, sniff position
6) placement with proof - through vocal cords, EtCO2, auscultate, SpO2
7) post intubation management - ETT secured, OG/NG, CXR, sedation, documentation, vitals, family
sniff position
face parallel to ceiling
safety check
- correct size OPA
- ambu bag
- PEEP valve set on ambu bag
- suction
airway: what do you check?
- ETT
- size
- position at teeth/gum (in cm)
- ?cuff leak
- oral integrity
- secured
breathing: what do you check?
- RR, WOB
- lung sounds
- vent settings/monitored parameters
- vent synchrony
- SpO2
- EtCO2
- secretions
what is a ventilator?
- a machine that supports breathing
- provides breaths for a pt who can’t
- can provide supported breaths for ineffective breathing
- delivers O2 and positive pressure to lungs
- assists with ventilation by setting RR and Vt
- assists with oxygenation by setting FiO2 and PEEP
difference between normal breathing and mechanical ventilation
on inspiration, intrapulmonic and intrathoracic pressure is more positive WITH A VENTA
how is inspiration initiated?
either by pt (flow/pressure triggered) or by ventilator (time triggered)
what is reached at the end of inspiration?
set time, flow, volume and pressure
can you speed up or suck air out in expiration?
No, it is passive
important words to know
- RR (set or spontaneous)
- Tidal volume (amount of air in lungs from 1 breath)
- Minute volume
- PEEP (pressure at end of exhalation)
- Pressure (force we push in or result of volume)
- Alarms (set for volumes, rates, pressure etc)
normal Vt based on weight
6-8mL/kg IBW
minute volume normal
5-8L/min
PEEP affect on hemodynamics
- increased intrathoracic pressure
- decreased venous return, preload, contractility
- decreased CO
- decreased BP
what happens if you don’t have enough PEEP? too much?
not enough - alveoli collapse, poor oxygenation
too much - risk of overdistention causing barotrauma
with added PEEP what’s the CVP goal?
8-12mmHg
is CVP a direct indicator of volume status with PEEP?
no
what settings influences oxygenation on a vent?
FiO2
PEEP
what settings influences ventilation on a vent?
pressure (Control or support)
tidal volume
RR
minute volume
golden rule for vent
if you set pressure, volume will vary
if you set volume, pressure will vary
types of ventilation
- spontaneous mode (Pressure Support)
- controlled modes (volume control/assist control; pressure control)
- hybrid mode (SIMV)
when would you use pressure support ventilation?
- pt is able to breath on their own
- spontaneous breathing trials
- weaning from ventilator
- on the lowest settings: PSV 5, PEEP 5, FiO2 30%
PSV
- spontaneous mode
- pt must initiate enough breaths
- provides additional + pressure with each initiated breath
- augments inspiratory effort which influences tidal volume
what does the nurse set on PSV? what does the pt set?
we set: PS, FiO2, PEEP
pt sets: RR, tidal volume, minute ventilation
what is typical PS and PEEP on PSV?
PS: 5-20cm H2O
PEEP: 5-10cm H2O
IPAP = ______ EPAP = ______
IPAP = PSV (ventilation)
EPAP = PEEP (oxygenation)
what requires close monitoring in PSV?
RR and tidal volume
volume control (assist control)
- vent initiates a set number of breaths (typically 10- 16/min) and set tidal volume
- RTs calculate the pt’s tidal volume based on ideal body weight (not the same as actual weight) and aim for 6- 8mL/kg per breath
what settings does the nurse set on AC vent? what do we monitor?
we set: FiO2, PEEP, tidal volume, RR
monitor: minute ventilation, SpO2, PaO2, SaO2, CO2
benefits of AC vent mode
- guaranteed tidal volume and RR means consistent minute volume and greater control over CO2 clearance
- total support of ventilatory efforts reduces patient demand
example pt populations:
- post RSI (paralyzed)
- sedated
- procedural (bronch, trach, endoscopy)
peak inspiratory pressure
- aka PIP or pPeak
- pressure that is generated by the ventilator to overcome BOTH airway resistance AND alveolar resistance.
- measured by ventilator with each breath in control modes of ventilation
how often is pPeak monitored? what it is influenced by?
- monitored hourly. if it keeps increasing = issues with compliance
- influenced by volume, compliance, airway and tubing resistance
repeated exposure to high pPeak pressures can cause?
lung damage
- barotrauma can result from elevated pressure in lungs
- volutrauma can result from overdistention of the lungs
may cause alveoli to rupture, leading to pneumothorax
goal pPeak
< 40cm H2O
plateau pressure: when is it measured? how often is it done? what does it reflect?
- measured at the end of inspiration, during an “inspiratory hold” done by RTs (static state)
- Done less frequently than pPeak (e.g. done with every vent monitor by RT, Q 4 hrs)
- Inspiratory hold prevents movement of air in or out of the system
- Reflects lung compliance
interfering pressures in plat
airflow, tubing, airway
plateau pressure equation
pPeak - interfering pressures = plat
what could indicate worsening compliance?
increasing/increased pPeak/PIP or plateau pressures
what does it mean if patient is riding the vent?
they are not making any effort to initiate breaths. completely dependent on vent
tidal volume (Vt) and expired tidal volume (Vte)
- tidal volume is the set volume of air delivered to the patient with each breath
- tidal volume is SET
- expired tidal volume is the volume of air that the pt exhales with each breath
- expired tidal volume is MONITORED
in AC is the RR set by pt or nurse?
determined by vent and patient - watch for pt breathing over rate. Vte is determined by vent.
what do we set in AC vent?
RR, Vt, PEEP, FiO2
pressure control ventilation (PC, PCV)
- vent delivers a set pressure and set RR
- pressure on inhalation + pt’s lung compliance = tidal volume
- pt’s tidal volume will vary with each breath and is influenced by the set pressure and lung compliance
- pt can breathe spontaneously and will receive set pressure control
vent settings on pressure control that is set
- FiO2
- PEEP
- pressure control (15-25cm H2O)
- RR (12-20/min)
vent settings on pressure control that we monitor
tidal volume, minute volume
pPeak in pressure control is…
pPeak = PC + PEEP
when would we use PCV?
- to limit pressure on lungs
- concerned about volu/barotrauma (laminar flow)
- in pts with decreasing lung compliance
- if a pt is too weak for PSV, we use PCV as rest mode during prolonged weaning
- usually (not always) more comfortable than AC
benefits of PC over AC
- constant airway pressure can recruit and
improve alveolar distention across all lung
fields - in AC, air flows to the most open and
compliant alveoli first (leading to regional
over-distention) - areas with low resistance will get more air
than areas of the lungs with higher
resistance - as volume is forced into the lungs, low
resistance areas will receive more of this
air and are prone to volu/baro trauma
how does laminar flow help in pressure control ventilation?
Gas in the centre moves slightly faster than the
gas on the side (more effective at opening
smaller airways) = laminar flow helps open smaller airways even if they have higher pressure
what is determined by both the vent and the patient on PC?
- RR (determined by vent and pt, pt can breathe over set rate)
- Vte (determined by vent on pressure setting and pt [lung compliance, pressure in airway, tubing])
what are warnings with controlled mode of ventilation?
- can be uncomfortable for awake pts
- can cause a/desynchrony with own breathing and vent pre set breaths = anxiety, coughing, resisting delivered breaths = high pressures and low Vts
- need to act stat - more sedation? change to spontaneous mode?
hybrid mode of ventilation: SIMV
- synchronized intermittent mandatory ventilation
- usually PSV + AC
- vent delivers a set respiratory rate and a set tidal volume for each controlled breath (a minimum minute volume is guaranteed)
- for additional breaths, the patient determines their tidal volume.
- guaranteed minute volume in the background is the benefit
vent settings for SIMV
- RR (typically 4-10/min)
- AC breaths: Vt (aka controlled breaths) 6-8mL/kg
- PS breaths: PS (aka spontaneous breaths to help support pt initiated breaths)
- FiO2 and PEEP
what do we monitor on SIMV mode?
- RR: may breathe over set rate but will receive PS on these breaths
- Vte: might vary between spont and controlled breaths
- Mve: depends on if pt is taking any spont breaths
- pPeak: will fluctuate with VC and pt-initiated breaths
when do we use SIMV?
- weaning from sedation post op
- used in PACU/CSICU more often
troubleshooting alarms
- always check pt first
- silence alarm if appropriate
- call for help if needed
- when in doubt, bag the pt
high pressure alarms
pressure in circuit too high
causes:
- coughing, gagging
- bronchospasm
- fighting the vent
- ETT occlusion
- kink in tubing
- increased/thick secretions
- water in vent circuit
low pressure alarms
pressure in circuit too low
causes:
- tubing disconnect
- loose connection
- leak
- extubation
- ETT cuff deflated
how do you know when a pt is ready for extubation?
- has the cause improved/resolved?
- can the pt protect their airway (cough/gag/GCS)?
- minimal vent settings (PSV)
- normal ABGs
- hemodynamically stable
- physical assessment
- pending procedures/scans?
weaning methods
- progressive decrease in PS mode (PSV 5 PEEP 5 FiO2 30% OR
- spontaneous breathing trial
spontaneous breathing trial
- CPAP on vent
- lasts 30-120min
- T-piece trials (no vent alarms)
- hemodynamic & patient parameters determine if a pt passes or fails (i.e., HR/ RR/ agitation…)
- different weaning pathways may be prescribed
what can weaning cause?
more work for pt, increased demand. anxiety and discomfort. do when pt is well rested. given periods of rest (control mode).
weaning failure - objective criteria
- HR >140/min or sustained increase of 20% from baseline
- SBP <90 or >180
- RR >35/min for 5+ mins or inc WOB
- SpO2 <90%
- PaO2 dec by 10 from preweaning or <50
- marked diaphoresis, agitation or anxiety
neuro considerations for vented pts
- communication is challenging
- feel like you can’t breathe
- gagging/coughing
- hands are restrained
- sense of thirst
- delirium
- anxiety/agitation
- discomfort
resp considerations with pt-vent desynchrony
- bucking the vent
- vent settings and pts breathing patterns don’t match
- pt can show signs of resp distress
- treat the cause - vent mode change? pain anxiety agitation? developing VAP? decreasing compliance?
GI considerations
- gastric distention - pts swallow air = nausea and bubbles
- NG/OG for decompression
- mech vent >48hrs increases risk for gastric ulceration
- feed asap
- use PPIs/H2 antagonists
