Respiratory Failure - Exam 2 Flashcards by Johannah Crumpton

Describe the modified Allen test. When do you need to perform it?

need to perform before doing an ABG, if the pt fails the test you cannot perform ABG

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Name 5 things that an arterial blood gas test will tell you. Which value is the same as pulse ox?

Oxygen tension (PaO2)
Oxyhemoglobin saturation (SaO2)- same as pulse ox
Carbon dioxide tension (PaCO2)
Acidity (pH)
Bicarbonate concentration (HCO3)

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arterial oxygen saturation is O2 that diffuses from the _____ to the _______ and bind to _______

alveolus

pulmonary capillary

binds to hemoglobin

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What is SaO2 a proportion of?

proportion of RBCs with hemoglobin that are bound to O2

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**What is the best marker of oxygenation? What is it? What is considered abnormal?

Arterial oxygen tension (PaO2)

unbound oxygen that is dissolved in plasma

Considered abnormal if less then 80mmHg but needs to be 55mmHg or less to qualify for home oxygen per Medicare guidelines

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**What is the best marker of how well a patient is ventilating? What is considered normal? Abnormal?

Carbon dioxide tension (PaCO2)

normal is 40mmHg

Considered abnormal if above 45mmHg or below 35mmHg

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_____ is the most important and strongest buffer in the body. How is it regulated? What are the normal levels?

bicarb

regulated by changing the amount generated or excreted by the kidneys

Normal level between 22 – 26 mEq/L

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What is the normal range for pH?

7.35 – 7.45

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How is hydrogen ion concentration determined?

determined by the balance of carbon dioxide (PaCO2) and bicarbonate (HCO3) levels

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_____ are the product of normal metabolism. What happens next?

Hydrogen ions

the body must continually dispose of acid to keep pH within narrow range

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_______ links the respiratory and metabolic (kidneys) system.

Carbonic acid (H2CO3)

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Carbon dioxide – > carbonic acid conversion is catalyzed by an enzyme called______.

Carbonic acid – bicarbonate conversion requires ________

carbonic anhydrase

no catalyst

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T/F: Compensatory responses help normalize the pH but usually do not return the pH fully to normal

True

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Appropriate compensatory response requires normal functioning _____ and _____. Failure to develop a compensatory response defines the ?????

lungs and kidney

presence of a secondary primary disorder

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What should normal A-a gradient be? What is the formula to calculate a quick A-a gradient?

less than 10mmHg

(age +10)/4

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How does A-a gradient change with time? Is a larger or smaller gap better?

A-a gradient increases with age

smaller gap is better

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What does a normal A-a gradient tell you about the cause of hypoxemia? elevated?

normal:
Hypoventilation
Low inspired O2

elevated:
V/Q mismatch
Shunt
Impaired diffusion

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Draw the Dr. Sheppard chart on how to define acidosis vs alkalosis

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What is complete compensation defined as? Will the body ever over compensate? How long does it take?

if it brings the pH back into normal range

NO! the body will not ever over compensate

hours to days

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What are the normal ranges for pH, PaCO2 and HCO3? What numbers are ideal for each?

pH = 7.35 to 7.45 (7.4 is ideal)

PaCO2 = 35 to 45 (40 is ideal)

HCO3 = 22 to 26 (24 is ideal)

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pH = 7.32
PaCO2 = 52
HCO3 = 19

What type?

respiratory and metabolic acidosis

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pH = 7.34
PaCO2 = 50
HCO3 = 31

What type?

respiratory acid with incomplete compensation

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pH = 7.38
PaCO2 = 24
HCO3 = 19

What type?

metabolic acidosis with complete compensation

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pH = 7.46
PaCO2 = 42
HCO3 = 31

What type?

metabolic alkalosis w/o compensation

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pH = 7.39
PaCO2 = 41
HCO3 = 25

What type?

normal!!

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pH = 7.42
PaCO2 = 51
HCO3 = 33

What type?

metabolic alkalosis with compensation

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Name some causes of respiratory acidosis

Airway obstruction
Lung disease
Chest wall disease
Neuromuscular disease
Primary brain injury (ex. CVA, trauma), sleep apnea, drugs causing sedation like opioids.

aka anything that causes decreased ventilation

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Name some causes of respiratory alkalosis

Voluntary hyperventilation
Involuntary hyperventilation (anxiety states, asthma exacerbation, CNS disease)
Lung disease causing hyperventilation (remember back to PE lecture)

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**Asthma pt with resp alk now having resp acidosis with accessory muscle weakness. What do you do?

ventilation

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What are some causes of metabolic acidosis?

bicarb loss: think GI

increased acid load: lactic acidosis, DKA, acid ingestion

impaired acid excretion: think renal failure

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When do you need to calculate the anion gap?

when primary disorder is metabolic acidosis

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What does the anion gap measure? What is the formula? What is a normal anion gap?

Measures the difference between cations (positively charged ions) and anions (negatively charged ions) using the formula below

= (Na) + (K) – (Cl) + (HCO3)

less than 12, greater suggests the presents of anions that cannot be measured

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What are the 4 MC causes of anion gap metabolic acidosis?

lactic acidosis, ketoacidosis, acute renal failure and toxic acids

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What is the mnemonic for causes of anion gap metabolic acidosis? Which 2 were highlighted in lecture?

M – Methanol (ex. Windshield washer fluid, bad moonshine)
**U – Uremia (BUN >60)
D – Diabetic ketoacidosis

P – Paracetamol (acetaminophen)
I – Isoniazid, iron
**L – Lactic acidosis
E – Ethylene glycol (ex. Antifreeze)
S – Salicylates (ASA)

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What is the cause of non-anion gap acidosis?

Caused by loss of bicarbonate or decreased acid (H+) excretion

think diarrhea and renal tubular acidosis

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What are some causes of metabolic alkalosis?

volume contraction: dehydration, over diuresis

loss of hydrochloride: vomiting, gastric suction, taking excessive antacids

hypokalemia

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What is an acute lung injury?

A term that encompasses a continuum of clinical and radiographic changes that affect the lungs causing respiratory failure in the critically ill patient

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What is acute lung injury characterized by? What is the most severe form of the illness?

acute severe hypoxia that is not due to the heart (non cardiogenic pulmonary edema). Acute hypoxemic respiratory failure following a systemic or pulmonary insult without evidence of heart failure

ARDS (acute respiratory distress syndrome)

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______ is most common form of non cardiogenic pulmonary edema and most severe form of acute lung injury. What does it cause?

ARDS

causes hypoxemic respiratory failure

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What is the MC cause of ARDS?

sepsis- most common cause in 1/3rd of causes

What are some examples of causes of ARDS?

sepsis
shock
lung contusion
toxic inhalation
near-drowning

_______ cause of ARDS is usually immune mediated

multiple transfusions

What is the pathogenesis behinds ARDs? Where does damage mainly occur? What is the pathological hallmark?

Pro-inflammatory cytokines cause lung injury

Damage occurs mainly at the capillary and alveolar cells

Pathological hallmark is diffuse alveolar damage (DAD on imaging report)

What pulmonary disorder causes excess fluid to accumulate in both the interstitium and alveoli which causes ______, _______ and ________. Also, the cell damage leads to ????

ARDS

impaired gas exchange,
decreased compliance
Increased pulmonary arterial pressure

decreased production of surfactant

What is the dx criteria for ARDS?

Acute onset within 1 week of known clinical insult (usually sooner)

Bilateral pulmonary infiltrates

Respiratory failure not fully explained by heart failure or volume overload

PaO2/FIO2 ratio < 300mmHg

What is FIO2?

fraction of inspired oxygen

What is the severity of ARDS based on? What are the categories?

Based off of level of impaired oxygenation

Mild - PaO2/FIO2 ratio between 200-300mmHg

Moderate-PaO2/FIO2 ratio between 100-200mmHg

Severe - PaO2/FIO2 ratio less than 100mmHg

Rapid onset of profound dyspnea usually within 12-48 hours after the initiating event

SOB, tachypnea, intercostal retractions and crackles on physical exam

What am I?
**What is a highlighted additional s/s?
What is an additional common finding?

ARDS

Marked hypoxemia occurs that does not respond to standard supplemental O2

multiple organ failure-> kidneys, liver, cardiovascular, CNS

What will the CXR show on a pt with ARDS?

CXR shows diffuse or patchy bilateral infiltrates that rapidly progress and characteristically spare the costophrenic angles

Heart size likely normal and small or no pleural effusions

Air bronchograms are seen in 80% of patients

Are IV steroids effective for ARDS?

NO! and nothing is effective for preventing ARDS

What is the tx for ARDS? What position?

treat the underlying condition

tx secondary conditions (sepsis)

supportive care: think oxygen and ventilator (if neccessary) Low Tidal Volume Ventilation (LTVV) is preferred

prone positioning

strategies to decrease O2 consumption (sedatives, analgesics and antipyretics)

How do you treat hypoxemia related to ARDS? What do you need to keep the PaO2 above?

Requires tracheal intubation mechanical ventilation

Supplemental O2 required to maintain the PaO2 above 55mmHg

What do you need to keep the FIO2 at? Why?

Efforts to keep FIO2 less than 60% as soon as possible in order to avoid O2 toxicity

What is PEEP? When is it used? What does it put the pt at risk for? What does it improve?

Positive end-expiratory pressure

used to prevent alveolar collapse
aka in the pause before next breath, airway collapses during pause in between breathes

increases pt risk for barotrauma

Has been shown to improve hemodynamic outcomes but NOT shown to improve mortality

What is the outcome associated with ARDS?

Mortality ranges 30-40% and increases to 90% when associated with sepsis

Median survival is 2 weeks

Most survivors are left with chronic pulmonary symptoms that may improve with time (cough, dyspnea, lung fibrosis)

Define respiratory failure. Is it a dz or condition?

Inability of the lungs to meet the metabolic demands of the body. This can be from failure of tissue oxygenation and/or CO2 elimination

condition! that occurs as a result of one or more diseases involving the lungs or other body system

What are some potential causes of respiratory failure?

carotid body ressection
CN IX compression
obesity
kyphoscolosis
airway obstruction
medulla: infection, bleeding, trauma, syringomyelia, drugs
spinal cord transection, poliomyelitis
guillain barre syndrome
myasthenia gravis
myotonic dystrophy

What is type 1 respiratory failure? What is another name for it?

lungs fail to provide adequate oxygenation of the blood (PaO2 <60mmHg)

hypoxemic respiratory failure

What is the MC form of respiratory failure? What is it caused by?

type 1 respiratory failure

Caused by diseases that interfere with O2 exchange, but ventilation is maintained
Occurs when significant intrapulmonary shunting or V/Q mismatch is present

aka PCO2 is normal but low PO2

What are some causes of hypoxemic respiratory failure? What type?

Decreased inspired O2 tension (↓PIO2) like in high altitude
V/Q mismatch (COPD)
Diffusion limitation (fibrosis)
Intrapulmonary shunt: Pneumonia, Atelectasis, CHF, ARDS

If your patient has type 1 respiratory failure with a normal CXR, What does that makes you think?

COPD
intracardiac shunt (right to left)
pulmonary embolism

If your patient has type 1 respiratory failure with a focal infiltrates on CXR, what does that make you think?

Atelectasis
Pneumonia

If your patient has type 1 respiratory failure with a diffuse infiltrates on CXR, what does that make you think?

Cardiogenic pulmonary edema
Noncardiogenic pulmonary edema (ARDS)
Interstitial pneumonitis or fibrosis
Infectious (bilateral pneumonia)

define type 2 respiratory failure. What will O2 and PaCO2 levels look like?

Type 2 – Defect in ventilation (CO2 elimination)

low O2 and PaCO2 will be elevated. PaCO2 > 50mmHg

In type 2 respiratory failure, what does the pH depend on?

pH depends on the level of bicarb buffering

Level of bicarbonate depends on the duration of hypercapnia since renal response occurs over days (2-5 days)

What are some causes of type 2 respiratory failure?

Respiratory center dysfunction (medulla)

Drug overdose, CVA, tumor

Central Hypoventilation= Odiene’s curse: varing degrees of involuntary ven

Neuromuscular disease: Polio, myasthenia gravis, spinal injuries, guillain- barre

chest wall/pleural dz

upper airway obstruction

peripheral airway disorder

What are some causes of type 2 respiratory failure? What is the arterial pH?

Sedative drug over dose
Acute muscle weakness, ex. Myasthenia Gravis
Severe lung disease
Acute on chronic respiratory failure

arterial pH will be low

COPD pt with pnue would be what type of respiratory failure?

type 2 and would need to be ventilated

What are the the main s/s of hypoxemia?

dyspnea, cyanosis, confusion, anxiety, delirium

What are the main s/s of hypercapnia?

dyspnea and HA, papilledema, asterixis, tachycardia

What is asterixis?

dorsiflex hand movements that rhythmically flaps

What is the main goal in hypoxemic respiratory failure? What else do you need to keep in mind?

Keeping O2 sat ≥ 90% or PaO2 ≥ 60mmHg

not to OVER oxygen the pt for the fear of causing progressive respiratory acidosis

What is the generic rule for supplemental oxygen?

For every liter increase in O2, FiO2 increases about 4%

What is a SE that you need to be mindful of when a pt is using a nasal cannula? What is considered low flow? high flow?

Higher flow rates can dry out the nasal mucosa fast

low: 1-6 L/min (FiO2 of 24% to 44%)

high:up to 10 L/min

How often does the nasal catheter need to be changed?

changed nostrils, every 8 hours

the simple face masks delivers FIO2 of ______ at flow rates of ______ respectively. Why would you NOT want to use below the min level?

40 to 60%

5 L/min to 8 L/min

Never use less then 5 L/min as patient may rebreathe most of their own air and become hypoxemic/hypercapnic

Partial rebreather mask delivers FiO2 of ______ at a flow rate of ______ respectively. How does it increase FIO2?

35% to 60%

6 L/min to 10 L/min

by recycling expired O2

O2 reservoir bag allows the patient to rebreathe the first 1/3 of exhaled air (dead space air)

Non rebreather mask delivers the highest FiO2 ______ at a flow rate of _____. What do the two one-way valves prevent?

possible 95%

10-12 L/min

Entrance of room air during inspiration
Retention of exhaled gases during expiration

venturi mask delivers FiO2 varying from______ at flow rates of ______. This mask is a good choice for _____ pts

24% up to 60%

4 L/min to 10 L/min

COPD

______ is first line therapy in COPD patients with hypercapnic respiratory failure who can:
Protect their own airway, handle their own secretions, tolerate the BPAP mask. What is their goal?

Noninvasive positive pressure ventilation (NPPV)

to reduce intubation rates and the amount of ICU stay

What is important to note about Bilevel positive airway pressure (BPAP)? How does it work? When is it commonly used?

Patients must initiate each breath on most machines

Delivers preset inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP)

COPD, conditions causing respiratory muscle weakness and obesity hypoventilation

_____ is continuous level of positive airway pressure throughout respiratory cycle. When is it commonly used?

Continuous positive airway pressure (CPAP)

sleep apnea or cardiogenic pulmonary edema

What are some indications the patient needs to be intubated?

Hypoxemia despite supplemental O2

Upper airway obstruction

Unable to protect airway or clear secretions

Acute hypercapnia that does not quickly respond to noninvasive ventilation (CPAP or BiPAP)

Progressive fatigue, mental status changes, tachypnea, or use of accessory muscles

Apneas

_____ intubation is preferred since easier, faster and less traumatic than _______. Position of the tip of the endotracheal tube should be positioned at the level of the _____ and verified by _____

Orotracheal

nasotracheal

aortic arch

CXR

What are 3 benefits of mechanical ventilation.

Improved gas exchange
Decreased work of breathing
More precise titration of oxygen needs

What are the 2 different types of breaths?

vent initiated breaths

patient initiated breaths

What are volume control breaths?

Breaths are ventilator-initiated with a set inspiratory flow rate
Inspiration is terminated once the set tidal volume was reached

What are volume assist breaths?

Breaths are initiated by the patient with a set inspiratory flow rate
Inspiration is stopped when the set tidal volume was delivered

What is continuous mandatory ventilation mode?

Minute ventilation is determined entirely by the set respiratory rate and tidal volume

Pt does NOT initiate additional breaths and does not require any patient effort

think heavy sedation, pharm paralysis or coma

What is Intermittent mandatory ventilation (IMV) Mode?

Clinician determines minimum minute ventilation by setting the respiratory rate and tidal volume

The patient can increase the minute ventilation by spontaneously breathing addition breaths

What is Synchronized IMV (SIMV) Mode? What is a benefit?

vent breaths are synchronized with pt effort

support can vary from full to no support depending on the pt

helps to prevent muscle function decline

What is Pressure support ventilation (PSV) mode? When is it commonly used?

pt must trigger breath, no set respiratory rate

work of breathing is inversely proportional to the pressure support level

when weaning a pt from mechanical ventilation

What is PEEP? When is it commonly used?

Positive end-expiratory pressure

added to ventilation to prevent alveolar collapse with end expiration

commonly used with ARDS

What is the usually PEEP pressure? What pressure is used in ARDS?

normal: 5cmH20

ARDS: 20cmH20

What are 3 potential complications of PEEP?

Decreased cardiac output

Increased risk for barotrauma

Possibility of impairing cerebral blood flow (d/t decreased cerebral venous outflow which causes increased intracranial pressure)

What are the potential complications of mechanical ventilation?

barotrauma

ventilator-associated pneu

trauma

What are the general guidelines for lung transplant?

Appropriate age (usually under age 65)

Severe lung disease that is progressive

Limited life expectancy because of their lung disease

Good nutritional status and BMI less than 30

Good support system and mentally intact

What are the contraindications for a lung transplant?

Active smoking (within the past 6 months)

Active malignancy in last 2 years

Drug or ETOH dependency

Significant disease of other organs including CAD and heart failure

Untreatable pulmonary or extrapulmonary infection

BMI >35

Hep B, C or HIV infection (they have become relative contraindications recently

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Respiratory Failure - Exam 2 Flashcards

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