chapter 42 Flashcards
(37 cards)
define hypoxia
abnormal condition in which inadequate O2 is available to meet metabolic needs in tissue/cells
hypoxemia
abnormal deficiency of O2 in arterial blood
normal lab value 80-100
mild lab value 79-60
moderate lab value 59-40
severe lab value 39 and below (below 40)
clinical objective of oxygen therapy
correct acute hypoxemia
decrease symptoms of chronic hypoxia
decrease workload hypoxemia imposes on cardiopulmonary system (heart and lungs)
indications for oxygen therapy
acute care situations where hypoxia is suspected
severe trauma
acute myocardial infraction
short term therapy
surgical intervention
post anesthetic recovery
Evidence of documented hypoxemia
(at room air)
PaO2 less than 60mmHg
SaO2 less than 90%
These are ranges before desirable range for a specific clinical situation
a) PaO2 of healthy person
b) PaO2 for COPD person
Healthy: 80-100 mmHg
COPD: 55-75 mmHg
Who is at risk for retinopathy and what does it cause?
Premature infants
PaO2 greater than 80mmHg may contribute to this
Abnormal growth of retina causing vision impairments from excess oxygen
a) what happens when exposed to 100% FiO2 and what is it called
b) 25-30 hours
c) 30-72 hours
a) it is called oxygen toxicity
-pulmonary fibrosis and hypertension
-thickening of aveolar capillary
b)decrease lung compliance
-decrease exercise PaO2 (can not take in anymore O2)
-Increase in PaO2 - PAO2 gradient
-lung stiffening
c)decrease diffusing capacity
-can not expel O2 to rest of body
tell me about Nasal cannulas
Delivers FiO2 of 24-44%
1-6 L/min
FiO2 depends on how much room air patient inhales in addition to O2
Device is well tolerated
add humidifier at 4 L/min or when patient is complaining of irritation
Advantages of nasal cannula as a low flow device
disposable
easy to use
well tolerated
provides low flow
low lost
Approximate FiO2 levels on nasal cannula
1 L/min 24%
2 L/min 28%
3 L/min 32%
4 L/min 36%
5 L/min 40%
6 L/min 44%
when would you use a bubble humidifier
when flow is at or greater than 4 L/min or patient is complaining of dryness
Transtracheal catheters
surgically placed in trachea
uses 40-60% less O2 to
achieve same PaO2 by nasal cannula
uses flow rates of 1.4 to 4 L/min
requires patience and cleaning
complications such as infection are possible
minute ventilation calculations:
a) rate of 14 BPM with tital volume 650 mL
b)rate of 20 BPM with tital volume 575 mL
c)rate of 18 BPM with tital volume 430 mL
d)rate of 6 BPM with tital volume 425 mL
a) 14x650=91000mv/1000= 9.1L
b)20x575=11500mv/1000=11.5L
c)18x430=77400mv/1000=7.74L
d)6x425=2550mv/1000=25.50L
Reservoir canulas
designed to conserve O2
Nasal reservoir
used often with COPD patients
pendant reservoir
1-10 L/min flow
FiO2 is 24-60%
humidification not needed
Simple mask
6-10 L/min liter flow
flow less than 6 causes carbon dioxide rebreathing
35-50% FiO2 range & varies depending on O2 input flow mask volume, extent of air mask volume, air leakage, and breathing pattern
air dilution through ports
Partial vs Non-Rebreather masks
PARTIAL: reservoir provides higher flow of FiO2 than simple mask
-no valves
-during inspiration, source O2 flows into mask and directly to patient
-During exhalation, source O2 enters bag
-Minimum of 10 L/min to prevent rebreathing and collapsing bag on inspiration
-FiO2 range- 40-70%
NON-REBREATHING: more commonly used
-minimum of 10 L/min but start at 15 L/min to prevent rebreathing
- FiO2 range is 60-80 but can go up to 100
-prevents rebreathing with 1 way valve
high flow vs low flow devices
HIGH FLOW: minimum of 60% FiO2
-exceeds patients inspiratory flow
-not affected by patients breathing pattern
LOW FLOW: maximum of 60% FiO2
-goes from 1-6 or 1-10 L/min
-does not exceed patients inspiratory flow
-needs patients inspiratory flow
Magic Box Calculations
a) Set FiO2 is 40% and flow set to 8 L/min
b) Set FiO2 is 35% and flow set to 8 L/min
c) Set FiO2 50% is and flow set to 12 L/min
a) 32 total flow
b) 42.4 total flow
c) 31.2 total flow
what happens if port in obstructed on air-entrainment mask
increase of FiO2, total output flow decreases
(venturi mask) (bernuli effect)
four main functions of high flow nasal cannula
-delivers high flow FiO2
-meets or exceeds patients inspiratory flow
-carbon dioxide washout from dead space
-generates distending positive airway pressure (increasing functional residual capacity)
blending system
provides high O2
Separate pressurized air and O2 source input
gases are put together and mixed with precision value
allows precise control over FiO2 and total flow output
bag- valve mask system
self-inflating bag and non-rebreathing valve features
provides up to 100% O2
Often used in often used in emergency life support settings
manual ventilator
three P’s of oxygen selection
1) purpose:
why u are performing a certain procedure/ using a certain device
-increase FiO2 sufficiency to correct arterial hypoxemia
2) Patient:
symptoms and other key factors determining care
-considerations such as age, alertness, tracheal airway, ventilation, mouth vs nose breathing
3) Performance:
how well device is working
-system varies to actual FiO2 delivered and stabilizing of FiO2 under changing patient demands
