O2 Therapy + MV - Exam 2 Flashcards
What is low-flow oxygenation?
Oxygenation that has variable air entrainment
-Patient breath is a combined mix of air and oxygen
What affects oxygen delivery in low-flow oxygenation?
- reservoir
-nasopharynx and oropharynx are anatomic reservoirs - flow rate
- ventilation pattern of patient
-increased TV and RR reduces inspired FiO2 - fit
Nasal cannula (Liter flow, FiO2%) Low/High flow?
1-6L
FiO2 - 4% increase for each 1L
Low flow
Simple mask (Liter flow, FiO2%) Low/high flow?
No reservoir
Liter flow 5-8L
FiO2 - 35-60%
-FiO2 DECREASES with MV increase
Low flow
Partial rebreather (Liter flow, FiO2%) Low/high flow?
Has reservoir, No valve=150mL anatomic dead space -rebreathed
10L + Flow
FiO2 60-80%
Low flow
Non-rebreathing mask (Liter flow, FiO2%) Low/high flow?
Unidirectional valve + reservoir bag (should be 1/3-1/2 full with 8-15L/min)
10L Flow=FiO2 100%
Low flow
Face tent (liter flow, FiO2%) Low/high flow?
4-8L flow
FiO2 30-55%
Low flow
-good for eyes, post-nasal, and plastic cases
T-piece/trach mask (liter flow, FiO2%) low/high flow?
4-8L/min with FiO2 30-55%
-BYPASSES NASO+OROPHARYNX SO NO AIR ENTRAINMENT
-could decrease FiO2 without a reservoir
Low flow
What is a high flow system?
-Flow rate and reservoir > MV to supply the precise O2 and air mix
-Flow is specific and consistent FiO2 REGARDLESS of MV
FiO2% ranges from 24-50%
-larger port=less FiO2
-higher flow does NOT increase FiO2
Oxygen administration is contraindicated in which patient population?
COPD
-loss of hypoxic drive
What is absorption atelectasis?
Nitrogen washout in the alveoli causing alveolar collapse (atelectasis)
What is oxygen toxicity?
High conc O2 (>50%) given >48hr
-removing hypoxic drive(COPD!)
-use minimal FiO2 on venturi mask, goal is SaO2 88-92%
-increase free radical formation causing damaged membranes, proteins, and lung structures**
What is retinopathy of prematurity?
Retinopathy of Prematurity; blindness occurring in premature infants and newborns as a result of high PaO2, not high FiO2
Three indications for mechanical ventilation?
Acute hypoventilation/apnea
High V/Q
Low V/Q
What are causes of VALI? (Ventilator associated lung injury?)
- Volutrauma
-Overextension of alveoli (too much TV) - Barotrauma
-Positive pressure effects such as pneumothorax (too much PEEP) - Atelectrauma
-Collapse and reinflation of alveoli (not enough PEEP/too much FiO2) - Biotrauma
-Release of inflammatory mediators (disease process)
How to prevent VALI from barotrauma?
-Peep < 15 cmH2O
-PEEP = BMI x 0.3
Pt is 80kg and 6’1. 6’1=73in=185.42cm=1.85m
(80/3.438) = 23.3 BMI
PEEP = 6.98cmH2O
What is tidal volume?
Vt is volume per breath
What is minute ventilation?
MV = Vt x RR
The volume of gas inhaled and exhaled in a minute
What is laminar flow?
Streamlined flow: Molecular movement when there is little friction
What is turbulent flow?
Chaotic and Random flow: Molecular movement with friction (increased resistance)
What is peak flow?
Velocity at which gas is delivered to patient
50-80 L/min
What is peak pressure?
Highest pressure reached during ventilator breath
Spontaneous breath: Patient effort
MV: Inspiratory pressure + inspiratory flow rate
Increased by PEEP
Volume Control
Preset TV, RR, I:E ratio
PIP can change
-pressure and volume limit usually
-Inspiratory pressure is 10-15 cmH2O higher than peak pressure of normal breath
higher pressure for same ventilation as PCV
Controlled Ventilation
A type of ventilation in which the anesthetist controls the respiratory rate, the tidal volume, and the peak inspiratory pressure. In this type of ventilation, the patient does not make spontaneous respiratory efforts.
assist control ventilation
For spontaneous breathers:
-DETECTED breath receives preset VOLUME, WILL give breath on TIMER if pt is apneic
-can induce breath stacking and resp alk
Preset: TV, RR, Insp. Flow, PEEP, FiO2
PIP: VARIABLE
intermittent mandatory ventilation (IMV)
Gives mandatory breaths and if pt takes spont breaths they are not supported by machine, but can happen based on patient’s own ability
-TV and RR set but if pt breathes spont they can increase MV bc Vt is variable if spont
-PIP variable
SIMV
Must set pressure support for spontaneous breaths, delivers set volume
PIP variable
Same as IMV, however it will not deliver a mandatory breath on top of a spontaneous breath-weaning mode
-Senses mandatory breaths and synchronizes, still delivers set amount of TV/ MV while avoiding bucking/stacking
Pressure control
Preset RR, Insp. flow, PIP, PEEP, FiO2, I:E ratio
VARIABLE TV
Ventilation is delivered until the set peak pressure is reached
-better ventilation at lower pressures
-good for lap + robot cases, COPD, one lung
What is protective ventilation?
6-8 mL/kg(IBW) TV
14-16 RR
15-20 PEEP
With pressure control-less barotrauma
reduces sheer pressure, optimized recruitment, higher mean airway pressure for better exchange, helps wean
-better post heart and post (non obese) abdom cases
What is pressure control inverse ratio ventilation
Longer inspiratory period than expiratory period
airway pressure release ventilation (APRV)
mode of mechanical ventilation that allows unrestricted, spontaneous breaths throughout the ventilatory cycle
-inverse IE ratio, 2:1
-on inspiration the patient receives a preset level of continuous positive airway pressure, and pressure is periodically released through exhalation to aid expansion
-avoid in pt with increased resistance and air trapping
Pressure control volume guarantee/pressure-regulated volume control (PRVC)
TV consistent
Inspiratory pressure variable, but programmed by anesthetist
What is SIMV/PSV modes? (SIMV with pressure support)
Mandatory volume and respiratory rate, but also supports spontaneous breath with pressure
What is pressure support with protection? (PSV-PRO)
-lets pt spont breathe but switches to ACV or SIMV if apneic (10-30s) and switches back if they breathe again
-Preset: FiO2 + PEEP, PIP is capped
-Variable: Vt, insp flow rate, RR, PIP (adjusts to overcome resistance)
-good for maintenance and emergence bc supports EtCO2 and MV while preventing barotrauma + WOB
-senses pt’s effort and delivers pressure breath with every respiration to increase Vt
-often used as add on for ACV or SIMV
ARMS methods?***
CPAP after surgery
-sustained inflation: 50-90sec to PIP of 40cmH20
-incremental increasing of PEEP: stepwise manner, 4-20cmH2O
PEEP during surgery, ARMS Q 1hr or if pO2 drops**
What is PEEP?
Increases end-expiratory airway pressure to a value higher than atmospheric to keep alveoli inflated
When is PEEP contraindicated?
COPD
What PEEP settings cause barotrauma?
PEEP > 10 cmH2O
Mean airway pressure > 30 cmH2O
PIP > 50 CMH2O
How does PEEP affect the CV and neurologic systems?
Decreases BP
Increases ICP
What is CPAP? BiPaP? Indications?
CPAP: Positive pressure with inspiration
Spontaneous breathing
BiPAP: Positive pressure on inspiration and expiration
Spontaneous breathing
Indications: COPD with hypercapnia, cardiogenic pulmonary edema, hypercapnic/hypoxic respiratory failure
What causes increased compliance?
Emphysema, COPD
What causes decreased compliance?
Pneumothorax, CHF, atelectasis, abdominal distention, pleural effusion
How to set RR for SIMV?
Set RR to create 80% of minute ventilation demands
What is plateau pressure?
Pressure applied to the small airways and alveoli
-Measured by end-inspiration hold of 0.5-1 second
35 cmH2O < barotrauma
Peak flow rate for most patients
60 L/min
Pressure trigger sensitivity for most patients
-1 to -3 cmH2O
PSV
Preset PEEP
Preset FiO2
VARIABLE TV
Preset PAP
Delivers supportive pressure on inspiration until flow reaches a set level (generally 25% of peak flow)
WOB is inversely proportional to level of pressure support and flow rate
Normal MV
5-7L/min
How can you estimate the correct level of PEEP usage?
Lower inflection point + 2 cmH20
Definition of ARDS (numbers)
PaO2/FiO2 < 200
How to prevent VALI from volutrauma?
Use VT 6-7 mLs/kg IBW
How to prevent VALI from atelectrauma?
-Minimize FiO2 30-40%
-Low I:E ratio 1:1.5
-Use ARMS
VCV is best used on which pts:
Set MV (RR and Vt) meets the desired goal for body
-medically paralyzed
-sedated
-coma
-lack of pt incentive to increase MV
PCV is best used on which pts?
Improves compliance
-preg, laproscopic cases, obese, ARDS, system leak or LMA
Controls PIP to avoid risk of barotrauma
-LMA use, emphysema, neonates
Better Vt for less pressure
-laproscopic cases
SIMV PSV
-volume controlled
-pressure support can be added to help pt with any spont breaths, weaning mode
SIMV PC
-pressure controlled
-pressure support can be added to help pt with any spont breaths, weaning mode
PC VG
-pressure set, Vt set(MV)
-PIP changes (if compliance/ resistance changes) within range of PMax to achieve Vt with minimal pressure
-can be added on to SIMV, AC, CMV, and PSV
PSV PRO ideal pt
LMA
-protects from apnea, helps reduce WOB, gives pressure when pt attempts breath
CPAP + PSV
-gives constant support pressure once vent senses insp effort
-spont breathing that happens is shown via color change on wave
If on NC @ 4L/min, what is FiO2?
~37%
4*L/min +21 =FiO2
What is FiO2 of 2L/min NC
29%
FiO2=21+(4*L/min)