Pulmonary (part 3) Flashcards
____ ___ is inadequate gas exchange due to dysfunction of 1 or more components of the respiratory system
Respiratory failure
Respiratory failure can be ___, ___ or both
Acute, chronic
Type 1 respiratory failure is ____ respiratory failure
Hypoxemia
With type 1, lungs cannot ____ ___ because the alveoli are filled with fluid
Oxygenate blood
Examples of diseases that can cause type 1 respiratory failure:
-Pulmonary edema
-Pneumonia
-ARDS
Type 2 respiratory failure is ____ respiratory failure
Hypercapnic
With tye 2 respiratory failure, there is inadequate ____ due to a problem related to CO2 removal
Ventilation
What may cause type 2 respiratory failure?
-Chest wall deformities that don’t allow it to expand
-Insufficient quantities of air reach the alveoli
What signifies respiratory distress?
-Position
-Wheezing/stridor
-Speech
-Retraction
-Nasal flaring
-Level of consciousness
-Cyanosis
What is normal pH of the blood?
7.35-7.45
What is normal PaCO2 of the blood?
35-45 mm Hg
What is normal PaO2 of blood?
80-100 mm Hg
What is normal SaO2 of blood?
95-100%
What is normal oxygen saturation of the blood (SpO2)?
95-100%
What are advantages and disadvantages of using arterial blood for analysis of respiratory function?
-More data (O2 + acid-base, not influenced by hypoxemia, not influenced by pulsatile flow)
-Episodic
-Invasive (pain)
-Blood loss
What are advantages and disadvantages of using a pulse oximeter for analysis of respiratory function?
-Less data (O2 only; inaccurate < 70%, may require pulsatile flow)
-Continuous
-Noninvasive
-Home use
Types of pulse oximeters include…
-Light transmission through tissue (finger, toe, earlobe)
-Light reflected off Hgb (forehead, smartphone applications)
-Medical use vs non-medical use
Light transmission devices shine 2 wavelengths of light through the ___ ___ to a sensor on the other side
Vascular bed
Hemoglobin absorbs light at a different degree depending on the number of binding sites that are _____
Bound
An internal algorithm of the light transmission devices converts absorbance pattern to ____
SpO2
Light transmission devices require a ____ ____ and may not detect Hgb variants
Pulsatile flow
Light reflection devices can be ___ based (FDA certified or ____ based
Hospital; smartphone
Smartphone-based light reflection devices use a smartphone flash as a light source; the light is reflected off of ____ and detected by the camera
Hgb
An internal algorithm of he light reflection device converts the signal to estimate ____
SpO2
Both hospital and smartphone-based light reflection devices may have poor accuracy if SpO2 is under ___% if they are not for medical use
90
One problem with a 2-wavelength pulse oximeter is that while it detects Hgb that is bound, it doesn’t know what the Hgb is bound to; this is an issue for ___ ___ inhalation because PaO2 would come up normal (7-wavelength would show this)
Carbon monoxide
Possible sources of error with pulse oximetry:
-Device technology (not for medical use is unreliable with SpO2 under 90%; medical grade is unreliable under 70-75%
-Hgb variants
-Skin pigmentation (black pts are 3 times more likely to be hypoxemic)
-Decreased pulsatile flow
One concern as oxygen saturation decreases is that ____ diffuses out of plasma and into red blood cells
O2
What are acceptable levels for PaO2 and SaO2?
PaO2: 80 or more mm Hg
SaO2: 94% or higher
What levels of PaO2 and SaO2 indicate mild hypoxemia?
PaO2: 60 mm Hg
SaO2: 90% or higher
What levels of PaO2 and SaO2 indicate moderate hypoxemia?
PaO2: 55 mm Hg
SaO2: 88% or higher
What levels of PaO2 and SaO2 indicate severe hypoxemia?
PaO2: 40 mm Hg
SaO2: 75% or higher
What levels of PaO2 and SaO2 indicate tissue hypoxia and possible cardiac arrhythmias?
PaO2: <40 mm Hg
SaO2: <75% or higher
With the ___ ___ ___, multiple the FIO2 (in non-decimal form) by 5 to get the expected PaO2
Rule of 5’s
Room air has an FIO2 of ___
0.21 (this means that room air is 21% oxygen)
We can determine severity of respiratory failure by using the ____/____ ratio
PaO2/FIO2
A normal PaO2/FIO2 ration should be greater than ____
380
We can also assess severity of respiratory failure with the ___/___ ratio
SpO2/FIO2 ratio
Alveolar gas equation:
PAO2 = (PB - PH20) FIO2 - (PaCO2/R)
PAO2: alveolar oxygen tension in mm HG
PB: barometric pressure (sea level= 760 mm Hg)
PH20: water vapor session (fully saturated = 47 mm Hg)
FIO2: oxygen concentration in air (room air=21%)
R: respiratory quotient (VCO2/VO2=200/250=0.8)
To calculate the A-a gradient, subtract ____ from PAO2
PaO2
Normal A-a gradient is less than or equal to ____
10
The A-a gradient is the most sensitive indicator of diseases that interfere with ___ __
Gas exchange
A-a gradient helps to differentiate pulmonary from non-pulmonary causes of ____ and ____
Hypoxemia and hypercapnia
When on ____, A-a gradient is not precise, therefore it is only good to use A-a gradient on room air
O2
Oxygen content is the total O2 carries by ____
Blood
CaO2 is equal to…
(1.34 x Hgb x SaO2) + (0.0031 x PaO2)
-Bound hgb=19.49
-Dissolved plasma= 0.4
Normal CaO2 is ___-___ mL O2/100 mL of blood
17-20
What are 2 non-acute mechanisms of hypoxemia?
-Less inspired oxygen
-Diffusion defect
What are 3 acute mechanisms of hypoxemia?
-Hypoventilation
-V/Q imbalance
-Shunt
At higher ____, barometric pressure is lower
Higher
Barometric pressure at sea level is ____mm Hg, while barometric pressure at Mt. Everest is ____ mm Hg
760; 253
At higher altitudes/lower barometric pressure, there is a _____ PAO2 (blood oxygen)
Lower
When is barometric pressure a concern?
-Flying
-Climbing to high altitudes
What happens to pressure in a plane (even with it pressurized to less than 8000 ft)?
-Barometric pressure decreases
-PaO2 and SpO2 will decrease
-May require supplemental O2
With Covid-19, a company starting running faster trips to Everest; this included sending participants a ____ ____ that is connected to a device that extracts O2 from the air to help climbers get acclimated with higher altitudes
Hypoxicator Tend
Diffusion limitation results from…
-Loss of lung tissue
-Thicker A/C membrane
What happens with diffusion limitation?
-Okay at rest
-Severely short of breath with exercise
To help with diffusion limitation, you can give ___ ___ during exercise
Supplemental oxygen
The hallmark of diffusion limitation is ____ ___ ____
Hypoxemia on exertion
When someone with diffusion limitation exercises, they have insufficient ____ transfer
O2
Diffusion limitation is measured by…
DLCO (diffusing capacity of the lungs for carbon monoxide)
DLCO reflects ____ ____
Diffusion capacity
Normal ventilation requires…
-Contraction of the diaphragm
-Expansion of the chest wall
-Adequate tidal volume to flush CO2 from alveoli
If normal ventilation does not occur, what results?
-Increased CO2
-Decreased O2
-pH decreases (more acidic-> respiratory acidosis)
Common causes of hypoventilation are anything that decreases ____ ____
Alveolar ventilation
What are examples of things that would decrease alveolar ventilation and cause hypoventilation?
-CNS drive is depressed
-Rapid shallow breathing
-Decreased tidal volume
-Pain and splinting
What are the three zones of the lungs?
-Conducting
-Transitional
-Respiratory
___ ___ ____ is the last 1/3 of the inhale and is about 150 mL
Dead space ventilation
_____ is a deformity of the rib cage that can impact respiration
Kyphoscoliosis
With ___, a ventilator is commonly used to increase tidal volume
ALS
Acute exacerbation of COPD causes…
-Rapid, shallow breathing
-Small tidal volume (increase PaCO2)
-Primarily ventilate dead space
A _____ can increase dead space
Tracheostomy
We worry about dead space ventilation with restrictive diseases secondary to ____ conditions like ALS, post polio, Duchennes’s Muscular Dystrophy
Neuromusclar
When respiratory muscles lose function, ____ ____ falls, and CO2 is retained, causing acidosis
Tidal volume
To manage hypoventilation/dead space ventilation, we can use ____ ____ ____ (mouthpiece, mask, tracheostomy)
Positive pressure ventilation
An absolute shunt causes _____ without ____
Perfusion without ventilation
An increase in absolute dead space causes increased ____ without _____
Ventilation without perfusion
A relative ventilation/perfusion (V/Q) imbalance causes some decreased ____ and some decreased ____
Ventilation, perfusion
What are examples of ventilation/perfusion (V/Q) imbalances?
-Pulmonary embolus (dead space ventilation/no perfusion)
-COPD exacerbation (no ventilation)
-Community onset pneumonia (no ventilation)
A V/Q imbalance / Shunt is distinguished by the response to ____
O2
With a V/Q imbalance/Shunt, increase FIO2 and evaluate if there is a brisk response; if yes the cause is ____ and if no, the cause is ____
V/Q mismatch (brisk response)
Shunt (no brisk response)
With an absolute shunt or absolute dead space, increased ____ has little impact because O2 is not reaching the blood
FIO2
With a V/Q mismatch, the hypoxemia does respond to ___
O2
Covid can cause ___ ___ ___ by viral replication in nasal, bronchial, and epithelial cells and compromise of the epithelial-endothelial barrier
Acute respiratory failure
Covid can cause an inflammatory response and cause interstitial thickening, increased vascular permeability, and lead to the development of pulmonary edema and a ____
Shunt
In some patients with covid, they may have ____ hypoxemia
Silent hypoxemia
With silent hypoxemia, someone has a very low ____ without dyspnea, loss of consciousness, or loss of alertness
SpO2 (70%) (also low PaO2 of 40)
Long term outcomes of acute renal failure and covid:
-Restrictive disease
-Decreased diffusion capacity
-Fibrotic changes
-Dyspnea
-Decreased exercise capacity
At risk populations for respiratory failure:
-Obstructive sleep apnea (90% undiagnosed)
-Morbid obesity
-Extremes of age
-No previous opioid use
-Escalating dose requirements/habituation
-Concomitant sedatives or CNS depressant
Type I respiratory compromise is ___ ___ ___ ___
Hyperventilation Compensated Respiratory Disress
Type I respiratory compromise can be caused by…
-Sepsis
-CHF
-PE
Type II respiratory compromise is ____ ____ ____ (CO2 narcosis)
Progressive Unidirectional Hypoventilation
Type III respiratory compromise is ____ ____ ____
Sentinal rapid airflow (SpO2 reduction to precipitous fall)
Traditional monitoring of respiratory rate is with either…
-Impedance respiratory rate monitoring (ECG)
-Pulse oximetry
