respiratory integration Flashcards by Rebecca Webster

what does low Sa02 and high CO2 cause

Hypoxaemia
Hypercapnia = hypercarbia
Poor Tissue Perfusion
Poor Oxygen Capacity

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what does respiratory failure cause

Due to resp. path.
compensation
Cardiac Failure- Low Output
Anaemia

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what is the difference between dyspnoea, apnoea, hypopnea and bradypnoea

Dyspnoea – difficulty or discomfort in breathing
Hypopnoea – low minute ventilation, low tidal volume (Overly shallow breathing)
Bradypnoea – Low breathing rate
Apnoea – breathing stops, muscles of resp stop

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what is narcosis

a state of confusion, stupor, unconsciousness or euphoria (like drunkenness)

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what are narcotic drugs

opioids: morphine & heroine, reduce respiratory drive

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what are the types of narcosis

N2 Narcosis – during scuba diving, high partial pressure of N2 in blood leads to impairment of judgment. Can be relieved by ascending to less depth (i.e. toward surface)
CO2 Narcosis – when plasma CO2 is chronically high, body reduces homeostatic response to CO2 (ie less respiratory drive)

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is it possible to have a high PaO2 but a low SaO2

yes - Hb pathologies, other gases (CO) & poisons interfering with Hb binding to O2, etc
but not high SaO2 and low PaO2 - High SaO2 will unload O2 into solution until equilibrium is reached
so SaO2 is main measure of oxygen delivery to tissues

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what is clubbing

growth of nail beds due to chronic hypoxia

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what causes respiratory failure

Must be due to respiratory pathology

Cannot be due to homeostatic respiratory compensation for kidney or liver pathologies

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what causes respiratory failure type 1

Hypoxaemia, normal arterial CO2
breathing appropriately
Inspired O2 does not arrive inside capillaries of perfused alveoli (or at high concentration inside aorta)
eg V-Q mismatch, diffusion problems, shunt,
Transfer factor (DLCO)

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what causes respiratory failure type 2

Hypoxaemia with pathologically elevated CO2 due to respiratory causes
hypoventilation

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what is anatomical dead space

no gas exchange occurs
In adult: 150 ml, of tidal volume of 500 ml
While exhaling, this air is identical to atmospheric air
Physiological Dead Space = anatomical dead space + alveolar dead space

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what is residual volume

amount of gas remaining in the lungs after maximal expiratory effort
While inhaling, this air is identical to expired (ie high CO2, lower O2) alveolar air. Arrives from deepest recesses of alveoli.

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what is infection of airways

Airways have mucus and cilia to protect alveoli
When airways collapse or clog, CO2 builds up behind obstruction
makes breathing (moving air in and out of lungs) difficult

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what is infection of alveoli

When alveoli collapse or clog, no CO2 can leave blood: alv dead sp
This is the reason pneumonia causes V-Q mismatch

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what results in type 2 respiratory failure

acidosis
Increased airways resistance (COPD, asthma, suffocation)
Reduced breathing effort (e.g. narcotic drugs, opiates)
Partial closure of airways (e.g. chronic bronchitis)
Neuromuscular problems (e.g. myasthenia gravis)
Chest defects that interfere with breathing

what are types of type 2 respiratory failure

obstructive and restrictive

what is obstructive lung disease

An obstruction (or ubiquitous obstructions) in airways increase resistance to air flow
Typically more difficult to exhale
Rate of exhalation (FEV1) is smaller
But in many cases the total volume is preserved

what is restrictive lung failure

Lung/chest stiffness (or neuromuscular dysfunction) limit ability of lung/chest to drive airflow
more difficult to inhale
TOTAL VOLUME of exhalation, FVC, is smaller
So is the RV and the FRC (and thus the TLC)

what are examples of obstructive airways

COPD
Asthma
Bronchiectasis
CF

what is COPD

Often a mixture of emphysema and chronic bronchitis
Chronic bronchitis – airways narrow, mucus, cough
Emphysema – alveolar walls destroyed, making big air spaces that cannot be emptied, shortness of breath and fatigue

What are blue bloaters in COPD

air trapping (large chest), cyanotic. Mostly Bronchitis

What are pink puffers in COPD

Not cyanotic, increase internal airway pressure during exhalation to keep alveoli and airways open. Mostly Emphysema
CO2 retention – COPD patients who receive excessive supplemental O2 lose respiratory drive

why are pressure-volume curves are important in intubated (mechanically-ventilated) patients

Increases in impedance can be due to an increase in airway resistance, or a decrease in compliance
Airway Resistance is NOT measured at equilibrium

what is hysteresis in compliance

Normal. Slope of pressure vs volume is 1 / Impedance. Low slope = high impedance. Hysteresis is caused by finite delay of airflow due to friction in airway Restriction. Increased impedance due to decreased compliance. Obstruction. Increased impedance due to airway obstruction.

what is air trapping in obstructive disease

When increased air (with expiratory levels of O2 & CO2) remains in the lungs at the end of expiration. Caused by increased airway resistance (R) Results in Increased Residual Volume

what happens if air trapping is chronic

lungs remodel such that Total Lung Capacity is Increased Thoracic cavity may change shape Detected as increase in Residual Volume

what is spirometry like normal, obstructive and restrictive

``` A = Normal, late breath is convex B = obstructive, late breath is concave C = restrictive, late breath is convex like normal, but maximal volume is low b/c had less inspired air to start ```

what are restrictive pulmonary diseases

``` Difficulty with inhalation Interstitial lung disease e.g. pulmonary fibrosis Autoimmune diseases that reduce lung compliance Obesity e.g. obesity hypoventilation syndrome Scoliosis Neuromuscular disease E.g. muscular dystrophy or amyotrophic lateral sclerosis (ALS) ```

what is hypoventilation as a compensatory breathing change

``` Hypoventilation to acidify In metabolic alkalosis Vomitting Antacids Dehydration>Aldosterone Result: High CO2 levels ```

what is hyperventilation as a compensatory breathing change

``` Hyperventilation to de-acidify In metabolic acidosis Diabetic Ketoacidosis Chronic kidney disease (“kidney failure”) Also psychogenic Pain Anxiety Result: Low CO2 levels ```

what is respiratory failure type 1

Low PiO2 (e.g. at high altitude) V-Q mismatch (e.g. pulmonary embolism) Diffusion problem (e.g. Pulmonary Hypertension) Shunt (when some non-oxygenated blood is mixed with oxygenated blood in aorta blood)

Why does type 1 resp failure lead to hypoxaemia but not hypercapnia?

excess of O2 in compared to what blood can take up and excess CO2 in blood compared to expired air the airways remain patent, there is a homeostatic increase in minute ventilation to dispose of the extra CO2

what is an extreme type of V/Q mismatch

``` Physiological dead space Ventilation occurs, but NOT perfusion Example: pulmonary embolism Shunt Perfusion occurs, but NOT ventilation Examples: complete airway obstruction, lobar pneumonia True shunt does *not* respond to breathing 100% O2 VQ mismatch will benefit from 100% O2 ```

what causes V-Q Mismatch, Perfusion with impaired Ventilation

``` Conditions that cause changes in or collapse of a subset of the alveoli such as Lobar Pneumonia Asthma Pulmonary oedema ```

what causes Ventilation with impaired Perfusion

pulmonary embolus or decreased cardiac output Shock

Extreme V-Q Mismatch: How does Alveolar Collapse lead to Low O2 Saturation

pneumonia - lungs filled with with fluid but other lobes ventilate normally CO2 high - vasoconstriction stops perfusion alveolus collapses, CO2 does NOT build up as cannot unload where liquid is So this region of lung is perfused, but blood gets no O2 Air sacs downstream of blocked airway accumulate CO2