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Clinical Medicine 2 > Lecture 6 (hypoxia)-Exam 2 > Flashcards

Lecture 6 (hypoxia)-Exam 2 Flashcards

1
Q

Hypoxemia:
* What is it? (2)
* What does not necessarily indicate?

A
  • Abnormally low level of oxygen in the blood
  • O2 supply is inadequate to the body as a whole (general hypoxia) or to a specific region (tissue hypoxia)
  • Hypoxemia does not necessarily indicate tissue hypoxia
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2
Q

skipped slide

V/Q mismatch:
* Lung regions with low ventilation?
* Lung regions with high ventilation?

A
  • Lung regions with low ventilation compared to perfusion will have a low alveolar oxygen content and high CO2 content
  • Lung regions with high ventilation compared to perfusion will have a low CO2 content and high oxygen content
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3
Q

skipped slide

What is Alveolar-arterial gradient (A-a)

A

is the measure of the difference between the partial pressure of O2 in the alveoli and in the arterial blood – provides the efficiency of gas exchange in the lungs and can help narrow down possible causes of hypoxemia

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4
Q

Hypoxemia due to V/Q mismatch can or cannot be corrected? Explain

A

Hypoxemia due to V/Q mismatch can be corrected with low to moderate flow supplemental oxygen and is characterized by an increased A-a gradient.

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5
Q

Measurements of Oxygen:
* Arterial O2 sat?
* A-a oxygen gradient?

A
  • Arterial oxygen saturation – SpO2 via pulse oximeter or SaO2 via ABG
  • A-a oxygen gradient – Alveolar and arterial oxygenation - the difference between amount of oxygen in the alveoli (PAO2) and amount of oxygen dissolved in the plasma (PaO2)
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6
Q

⭐️

Obesity Hypoventilation Syndrome:
* What is another name?
* What is it?
* Prevalence increases?

A

“Pickwickian Syndrome”

Awake alveolar hypoventilation (elevated PaCO2 levels) in obese patient with alternative causes of hypercapnia and hypoventilation have been excluded-> Not fully getting rid of CO2, restrictive pattern

Prevalence increases with BMI
* BMI of 30-35 is 8-12%
* BMI >=40 is 18 – 31%
* BMI >=50 = 50%

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7
Q

Obesity Hypoventilation Syndrome:
* Correlation with OSA: Study of patients presenting with OSA? (3)

A
  • ~ 16% of patients with obstructive sleep apnea
  • ~ 22% of obese patients with OSA have OHS
  • ~20-30% in obese patients with severe OSA
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8
Q

⭐️

Obesity Hypoventilation Syndrome
* What is a major risk factor?

A

Obesity primary risk factor, severe obesity BMI > 50 is the major risk factor.
* Not all patients with obesity develop OHS

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9
Q

Obesity Hypoventilation Syndrome: Clincal findings
* BMI?
* May have what?
* All patients with OHS have some form of what?
* What many present late in disease?

A
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10
Q

When to suspect OHS:
* Strong What?
* BMI?
* Unexplained what? (2)
* Sxs of what?
* What happens with face?
* Increased what?

A
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11
Q

Diagnostics OHS:
* What do the labs show? (3)
* What happens to the blood?
* What does the PFTs?
* What does the CXR?

A

Restrictive pattern – decrease TLC, decreased FVC, decreased FVC1, normal FVC/FVC1 or increased ration

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12
Q

⭐️

Diagnostics OHS:
* What happens to your cardiac exam?
* What does the EKG show?

A

Cardiac – right ventricle enlargement from pulmonary hypertension on EKG and ECHO
* Right axis deviation of +110 or more
* Dominant R wave in V1 (R/S ration > 1 or >7mm tall) – tall R-eaves in right-sided chest leads
* Dominant S wave in V5 or V6 (R/S ratio <1,or > 7mm tall) – deep S-waves in left-sided leads

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13
Q

What is the diagnostic gold standard for OHS? ⭐️

A

Gold standard – sleep studies with continuous
carbon dioxide monitoring (polysomnography)

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14
Q

Treatment for OHS:
* What is the first line?
* All patients with OHS have some form of what?

A
  • First-line: Noninvasive positive airway pressure (PAP) together with weight loss are the initial first-line therapies
  • All patients with OHS have some form of sleep disordered breathing; PAP should NOT be delayed with the patient tries to lose weight.
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15
Q

Supportive Therapies: OSH
* Avoidance of what?
* Treatment of what?

A

Avoidance of alcohol and sedatives
* Relaxing the muscles of the airway

Treatment of comorbid conditions
* COPD
* Hypothyroidism

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16
Q

OSA:
* Most common what?
* What is it?

A
  • Most common sleep-related breathing disorder and has significant adverse health consequences
  • Recurrent obstructive apneas, hypopneas, and/or respiratory effort-related arousals caused by repetitive collapse of the upper airway during sleep
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17
Q

Epidemiology of OSA:
* Mc in who?
* Based on what?
* Prevalence increasing and may be related to?

A
  • Most common in older males
  • 15-30 % adult males, 10-15% adult females in US
    * Based on apnea-hypopnea index (AHI) 5 or more events per hour of sleep
  • Prevalence increasing and may be related to increasing rates of obesity or increased detection rates
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18
Q

Risk factors of OSA:
* What are they (5) ⭐️ ⭐️
* What are the less well established risk factors?
* Certain conditions carry higher prevalence?
* Increased what? ⭐️ ⭐️

A
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19
Q

⭐️

Clinical Features: OSA
* What happens in the daytime?
* Patient or partner complaints/concerns about?
* Morning what?
* What is common associated surgery?
* What will be on exame?

A
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20
Q

OSA

Snout and spin?

A
  • Snout – pt has the disease will test positive; if negative then pt most likely does not have the disease
  • Spin – pt does not have the disease; if tests positive then pt most likely does have the disease
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21
Q

How do you dx OSA? ⭐️

A

In-laboratory polysomnography (PSG) is the gold standard diagnostic test
* Full-night; split-night (diagnostic then therapeutic with PAP)

There are home sleep study devices, but gold standard is laboratory based.

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22
Q

What is this? What does the pink mean?
* What do you look for? what are the ranges?

A

Polysomnography
* Pink – not ok->Desaturation of O2 during apnea arrests

Look for apnea/hypopnea index. Look for total amount of apnea and hypopnea periods over # of hours of sleep (like 8hrs).
* Mild – 5-14.
* Moderate – 15-30
* Severe – 30+

23
Q

What is the STOP-band questionnaire?

A
24
Q

What are non-osa related conditions associated with sleep-disordered breathing?

A

Complicated OSA

25
Q

Treatment of OSA:
* Txt begins with what?
* What type of therapy?

A
  • Treatment begins with patient education and behavior modification.
  • Positive airway pressure therapy – should be recommended to all patients with diagnosed OSA.
26
Q

Conservative adjunctive treatments for OSA?

A
27
Q

Complications of OSA:
* MVA?
* Neuropsych?
* CV and cerebrovascalar?
* What happens to heart and lungs?
* What other diseases? (2)
* What happens to the liver?

A
28
Q
A

Risk factor – tongue enlargement; body mass !!

29
Q

What is normal pH, CO2, O2, HCO3?

A
  • pH – 7.35-7.45
  • CO2 – 35-45
  • O2 – 80-100
  • HCO3 – 22-24
30
Q

Acid-Base Disorders
* Are group of conditions characterized by what?
* Categorized as what?
* Dx is made by what? ⭐️
What is the txt? ⭐️

A
  • Acid-base disorders are a group of conditions characterized by changes in the concentration of hydrogen ions (H+) or bicarbonate (HCO3-), which lead to changes in the arterial blood pH
  • Categorized as acidosis or alkaloses and respiratory or metabolic, depending on the cause of the imbalance
  • Diagnosis is made by arterial blood gas (ABG) interpretation
  • Treatment is based on identifying the underlying cause

CO2 +H2O = H2Co3 = HCO3 + H
* The more CO2 -> the more H will be made and make the environment acidic (low pH)
* Lower CO2 will create alkalosis (high pH)

31
Q

pH and Acid
* Why is pH important?
* What is H+?
* H+ represents what? What does it cause?
* As the number of protons in the body goes up, the pH will go what?
* Blood has only one pH; regulating pH will alter all what?

A
32
Q

ACID BASE
* What is the CO2/bicarbonate system equation?
* The body can regulate what?
* Bicarb plus H+ produce what? The body can use what? What is breathed out?
* Clinically we can measure what?

A
33
Q

Factors that cause a right shift of the oxygen-hemoglobin dissociation curve
* When is o2 released?
* In these situations, hemoglobin has what?
* When does hemoglobin give up more oxygen more readily (3)

A
34
Q

Factors that cause a left shift of the oxygen-hemoglobin dissociation curve
* This type of shift prevents what?
* What does hemoglobin do?
* What are the causes (3)

A
35
Q

Skipped slide

partial pressure of oxygen rises, there are more what?

A

partial pressure of oxygen rises, there are more and more oxygen molecule available to bind with hemoglobin.

36
Q

Oxygen-Hemoglobin Dissociation Curve
* As PaO2 falls, hemoglobin saturation also falls as what happens?
* At around a saturation of 90%, the dissociation curve does what? Why?
* Since normal PaO2 is between 90-100 mmHg, an O2 saturation of 90% is not normal. An oxygen saturation of 90% corresponds to what?

A
  • As PaO2 falls, hemoglobin saturation also falls as hemoglobin releases oxygen to the tissues in the areas of the lower oxygen supply.
  • At around a saturation of 90%, the dissociation curve drops off quickly. This is because hemoglobin binding sites become less attracted to the oxygen as it is bound to fewer oxygen molecules.
  • Since normal PaO2 is between 90-100 mmHg, an O2 saturation of 90% is not normal. An oxygen saturation of 90% corresponds to a PaO2 of 60 mmHg, this is the minimum oxygen concentration providing enough oxygen to prevent ischemia in tissues.
37
Q

Bicarbonate:
* base or acid?
* Why organ regulated bicarb (how?) ? What is the normal limits?
* Can be used where?
* **Anything that happens with bicarbonate in the body is what type of process? **

A
  • BASE
  • Kidneys regulate, 24-26 is normal
  • Kidneys: Reabsorption of filtered bicarb by the proximal tubule & Renal excretion of hydrogen ions
  • METABOLIC PROCESS
38
Q

In a metabolic problem both, what can occur at the same time? Give examples?

A

In a metabolic problem both an acidosis and an alkalosis can occur at the same time as in incidence of vomiting (alkalosis) and diarrhea (acidosis) & aspirin

39
Q

⭐️

About CO2
* Comes from what?
* Acid or base?
* Produced where?
* How can it leave the body?
* Can only have what? Why?
* Changes can occur how fact?

A
40
Q

⭐️

Bicarbonate and PCO2
* What is there in the body?
* Bicarb is produced generated and regenerated where? Where can it be lost?
* Co2 is made where? Regulated through what?

A

There is a balance in the body.
* Bicarb is produced generated and regenerated in the kidney and can be lost anywhere in the body
* CO2 made everywhere in the body and regulated through the lungs

41
Q

Acid Base
* How does the healthy body regulate pH? (paCO2?

A

PaCO2 : by changing ventilation rates
* CO2 elimination via the lungs is the main way the body eliminates acid and maintains acid-base homeostasis

42
Q

HCO3 regulated?
* What happens in the kidney?

A
  • by reabsorption of virtually all the filtered HCO3- by the proximal tubule
    * this process simply keeps HCO3- from being lost in the urine and therefore prevents metabolic acidosis from developing.
  • Kidney controls the plasma HCO3- is by eliminating enough hydrogen ion to equal the fixed acid produced each day
43
Q

⭐️

What is metabolic acidosis/alkalosis? What is respiratory acid/alkalosis?

A

Metabolic acidosis:
* Caused by excess H+ production or HCO3- loss (such as in proximal renal tubular acidosis)

Metabolic alkalosis:
* Caused by excess HCO3- production or H+ loss (such as the renal system overwhelmed and can not reabsorb all bicarb thus it spills over into the urine)

Respiratory acidosis:
* Caused by CO2 retention (↓alveolar ventilation rate)

Respiratory alkalosis:
* Caused by excess CO2 removal (↑alveolar ventilation rate)

44
Q

How do you do the davenport diagram

A
45
Q

Metabolic acidosis:
* What are causes of increase H production?
* What are causes of HCO3 loss?

A
46
Q

What are the causes of respiratory acidosis?

A
47
Q

Metabolic alkalosis:
* What are the causes of H loss?
* What is the cause for HCO3 intake?

A
48
Q

What are the causes of Respiratory Alkalosis?

A
49
Q
A
50
Q

Mechanical Ventilation
* What is mechanical ventilation?
* What does a ventilator do?
* What does it maintain/improve?
* What does it remove?
* What does it decrease?

A

Under slide: Mechanical ventilation is a procedure often performed in patients in respiratory failure, which is defined broadly as the inability to meet the body’s needs for oxygen delivery or carbon dioxide removal. A ventilator delivers air, usually with an elevated oxygen content, to a patient’s lungs via an endotracheal tube to facilitate the exchange of oxygen and carbon dioxide.

51
Q

What are the indications for mechanical ventilation?

A
  • Cardiac or respiratory arrest
  • Tachypnea or bradypnea with respiratory fatigue or impending arrest
  • Acute respiratory acidosis
  • Refractory hypoxemia (when the PaO2 could not be maintained above 60 mm Hg with inspired O 2 fraction (FI O2 )>1.0)
  • Inability to protect the airway associated with depressed levels of consciousness

Signs/symptoms: hypoxia, tachypnea, agonal breaths, hypoxemia, hypercapnia

52
Q

What are some otehr indications for mechanical ventilation?

A
  • Shock associated with excessive respiratory work
    * Build up of lactic acid
  • Inability to clear secretions with impaired gas exchange or excessive respiratory work
  • Newly diagnosed neuromuscular disease with a vital capacity <10-15 mL/kg
  • Short term adjunct in management of acutely increased intracranial pressure (ICP)
53
Q

What are the two types of MV? (would know invasive)

A
54
Q

Invasive vs. Non- invasive Ventilation
* When would you consider non invasive ventilation?
* When is resp failure likely be resersible?

A

Clinical Medicine 2 (16 decks)

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