Mechanical Ventilation (guest speaker)

What to consider

-what type of airway is in place:ETT, trach?

-what are the vent settings and what do they mean

-how do I respond to vent alarms

-worst case: what do I do if the vent fails

-what goes into tx planning for someone on a vent/someone who is being liberated from the vent

Why mechanical ventilation

-impending or existing resp failure

-failure to oxygenate: cell level

-failure to ventilate: mvmt air thru lungs

-combo

-airway protection: mostly risk of aspiration, agitated, stroke, anaphylaxis, opioid OD

Types of airways

-Endotracheal tube (ETT)

-oral (99% of time) and nasal (usually in facial trauma that limits ability to open mouth)

-most commonly oral, but can be nasal

-passes thru vocal cords

-cuff/balloon passes below the vocal cords: maintain pos pressure to keep airways open, increase SA of alveoli

-pts almost always restrained to avoid self-extubation

-tracheostomy: for long-term vent nds, blockage or narrowing of airway (tumor/blockage). paralysis (failure to ventilate)-usually C4 level(loss of diaphragm), prep for surgery, airway obstruction in field (cric)

-done to make mobility more comfortable

-CPAP:pos pressure to keep airways open

-BIPAP: more serious, used to avoid intubation, correct ABG imbalances

ECMO slide

-way to buy time for transplant

-take blood out to oxygenate

-cupula: over O2 to provide humidity

Tracheostomy

-can be cuffed or cuffless

-cuff if positive pressure is needed

-cuffless if pt is on "mist" or "high-flow"

-must be cuffless or cuff must be deflated to allow for speech

-more long-term airway mgmt

Vent settings

-Tidal volume (VT)

-PEEP: pressure left in lungs at end of expiration: PT contraindicated at over 15

-Mode: 2 big ones

-Rate: RR

-FiO2:fraction of inspired O2

Tidal volume (VTe)

-normal ~500mL for males, 400mL for females

-in some cases Vt needs to be decreased to protect lung tissue

-ARDS, conditions where lungs become scarred/fibrotic. Too much stretch will cause damage.

PEEP

-positive end expiratory pressure

-pressure given in expiratory phase to prevent closure of the alveoli, allows for increased surface area and increased time for O2 exchange

-for those who aren't responding to supplemental O2 via standard nasal cannula or high flow nasal cannula

-BiPAP used as last ditch effort before intubation

-will typically permit lower supplemental FiO2 needs due to increase surface area for exchange

-5 mmHg-20mmHg

-PT contraindicated at 15 mmHg or more (unless bigger pt because it may just be necessary)

FiO2

-percentage of oxygen in the air being provided to pt

-21% (room air)-100%

-prolonged exposure to O2 can be toxic and cause oxidation and alveolar collapse/atelectasis

-FiO2 >0.5 (50%)

-greater than 50% FiO2 over time can be toxic

-PEEP is a useful tool to limit O2 exposure while a pt is mechanically ventilated (baseline PEEP is 5 on vent, PT contraindicated around 15)

-high flow nasal cannula or vent can get FiO2 up to 100%

FiO2 boost on monitor

-100% O2 for 2 mins

-if they are low or

-during deep suctioning

Vent Modes: pressure control (PC)

-controlled ventilation (pressure control)

-vent initiates all breaths at a pre-set rate and TV

-will block any spontaneous breaths

-pts may be heavily sedated, even paralyzed

-volumes may vary depending on compliance of the lungs:important when trying to avoid barotrauma

Vent modes: assist control (A/C)

-vent allows a pt to initiate a breath, then vent will deliver a pre-set vol

-vent set at a min rate so that apnea doesn't occur when a breath isn't initiated

-potential probs

-hyperventilation--->respiratory alkalosis

-vent dysynchrony, breath-stacking (issue of barotrauma, can compress heart and decrease CO)

Vent modes: synchronized intermittent ventilation (SIMV)

-similar to A/C but w/o a set TV

-pt allowed to take their own breaths with their own TV

-vent will deliver a breath with a set volume if the pt doesn't initiate a breath (beware of pts "riding the vent")

-can lead to low RR if the set rate is low and the pt isn't initiating breaths

Vent modes: pressure support ventilation (PS or SPONT)

-pt initiates a breath, vent delivers pressure only to overcome airway resistance and keep airways open

-pt controls rate, TV (will likely be variable) and minute ventilation (liters of air/minute, Vt X RR)

Vent modes: continuous positive airway pressure (CPAP)

-with CPAP machine or used as a vent mode

-positive airway pressure provided during both inspiration and expiration

-can set a pressure and a flow of O2 (L/min)

-FiO2 variable depending on O2 flow

-improves gas exch and oxygenation in pts who can breathe on their own

non-invasive ventilation: BiPAP

-Bi-level airway pressure (BiPAP)

-delivered via mask (full-face, mouth and nose, nasal only)

-similar to CPAP but can be set at one pressure for inhalation and another for exhalation

-better for correcting blood gas imbalance than CPAP

-can be used to avoid intubation

Vent alarms: high pressure

resistance/increase to pressure getting in

-secretions:

-kinking/poor positioning of ETT

-Pt biting tube or fighting vent

-water in tubing

-decreased lung compliance (ARDS)

-coughing: if person can't cough it's alarming/dangerous

vent alarms: low pressure

losing pressure-->lungs not getting proper air

-tubing disconnect from vent

-pt side vs vent side

-cuff leak: holds pressure in lungs so it doesn't escape. If lost you'll lose PEEP

-extubation

-if ETT migrates too far superiorly, pt is functionally extubated w/o tube exiting mouth, can be difficult to troubleshoot

-this is why knowing your "mark at teeth" before mobilizing is important (tubes are marked in cm's so you can note where it's marked at the teeth)

vent alarms: low/high volume, low (apnea)/high rate, high/low PEEP

-volumes and rate are just what they sound like

-High PEEP or Auto-PEEP (breath-stacking)-sometimes use opioids to decrease respiratory drive

-excessive pos. pressure remains in alveoli at the end of exhalation and during the next inhalation, gradually increasing alveolar pressure

-increased WOB, can cause alveolar damage

-does this sound like another term we've talked abt?

-increasing expiratory time can help

-another way we increase expiratory time with our pts?

-Low PEEP

-cuff or ETT leak

How should you respond to vent alarms?

-look at the patient

-if they're not distressed they're probably fine

If it's real; disconnect pt, ambu bag pt with 100% FiO2 from wall

Tracheal/Deep suctioning

-for pts who are unable to clear secretions by cough or huff

-risks: exposure to infection, desaturation (FiO2 boost), --arrhythmia (vasovagal response)

-ICP (intracranial pressure): cough

-can be done with ETT or tracheostomy

Oral suctioning

-much less invasive

-an important part of maintaining good hygiene and decreasing risk of aspiration

-Yankauer

Complications of mechanical ventilation

-asynchrony (bucking the vent)

-autoPEEP: breath stacking

-barotrauma: alveolar damage due to excessive pressure/volume

-hemodynamic compromise: more due to being in bed (increase HR, inability of BP to adapt)

-nosocomial infection

-anxiety/stress/disruption of sleep/wake cycle

-deconditioning/vent dependence: SBT-sponatneous breathing trial (losing resp drive)

-Decreased CO

-high intra-thoracic pressure from positive pressure from vent-->compression of heart-->decreased EDV-->decreased preload-->decreased CO/Q

Which pts don't come off vent well and therefore we try to use BiPAP for?

-COVID

-CF

Contraindications, precautions, signs of intolerance

MAP

-important for peripheral vascularization

-usual goal of > 60

When is a cuff leak good?

-when you're about to extubate

-shows that the airway isn't occluded

Time to move

-located all tubes, lines, drains

-secure whatever can be secured to the pt

-consolidate other lines as able (wound vac on base of IV pole or hanging from walker)

-make a plan for lines