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23 Cards in this Set
- Front
- Back
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These are the five causes of hypoxia:
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1. Hypoventilation
2. Decreased FiO2 3. Ventilation/perfusion (V/Q) mismatch 4. Right-to-left cardiac shunting 5. Alveolar diffusion defects |
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In both hypoventilation and decreased FiO2, the A-a gradient is ______.
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Normal, as both atmospheric and alveolar O2 concentration are decreased.
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Central chemoreceptors are located in the ______.
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Ventral portion of the medulla and are surrounded by cerebrospinal fluid (CSF).
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Central chemoreceptors are primarily responsible for hyperventilation during ______, while peripheral chemoreceptors are primarily responsible for hyperventilation during _______.
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Hypercapnia; hypoxemia
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Peripheral chemoreceptors located at the bifurcation of the common carotid arteries produce a maximal feedback response to the respiratory center at ______.
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PaO2 < 70 mm Hg
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As a person gains altitude, they are exposed to a lower ________, causnig them to become ______.
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Partial pressure of oxygen; hypoxemic
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What is primary respiratory alkalosis?
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A person blows off CO2 and their blood becomes alkalotic.
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CO2 is regulated primarily by ______. Therefore, acid-base disorder that stem from a change in CO2 are referred to as _______.
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Ventilation; respiratory acidosis or alkalosis.
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Concentrations of O2 and CO2 in serum are measured by their ________.
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Partial pressures.
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HCO3- is regulated by the ______.
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Kidneys
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Primary alterations in [HCO3] occur via ______ and are therefore referred to as ________..
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Metabolic abnormalities; metabolic acidosis or alkalosis.
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In metabolic acidosis, excess of _____ or ____ consume free _____.
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Organic acids; exogenous acids; HCO3-
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Metabolic alkalosis is less common than metabolic acidosis and usually results from _______.
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Excessive vomiting.
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The kidneys process of bicarbonate excretion and compensation takes ________ days.
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2-3
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Acetazolamide can be used to prevent _______ as it hastens the kidneys ________. Why does it work?
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Mountain sickness; bicarbonate diuresis; Gaining altitude --> Lower partial pressure O2 --> Stimulation of peripheral baroceptors --> Hyperventilation --> Respiratory alkalosis.
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Hyperventilation is triggered by peripheral chemoceptors. Increased minute ventilation decreases ______. Decreased _____ allows for a relative increase in ______.
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PACO2; PACO2; PAO2
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Risk factors for acute mountain sickness?
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• Rapid ascent to altitudes greater than 8000 feet (~2440 m)
• Unclear genetic predisposition to acute mountain sickness. |
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Normal [HCO3-] in blood?
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22-28 mEq/L
More than 28 is considered primary metabolic alkalosis. Less is primary metabolic acidosis. |
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Normal PCO2 in arterial blood?
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33-44 mmHg
More than 44 is considered respiratory acidosis. Less is respiratory alkalosis. |
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In metabolic acidosis, the ________ predicts the level of PaCO2 when compensation is complete.
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The Winter equation
PaCO2 = 1.5 x [HCO3-] + 8 |
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What is a useful stepwise way of thinking when assessing blood gas analyzes?
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1. Look at the pH to determine if the disturbance is acidosis or alkalosis.
2. Look at PaCO2 & [HCO3-] to determine the nature of the disturbance (respiratory or metabolic; e.g. PaCO2 > 40 is respiratory acidosis) |
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Most patients with COPD have ______ and are referred to as ________ because they have chronically elevated arterial _____.
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Chronic respiratory acidosis; CO2 retainers; PaCO2
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A patient with COPD has lab values:
• PaCO2 of 60 mm Hg Expected chronic compensation would be an increase in [HCO3-] of ______ and a decrease in pH of _____. |
As a rule of thumb, in chronic compensation for respiratory acidosis, the [HCO3] is elevated 2 mEq/L and the pH is decreased by 0.03 for every 10 mm Hg elevation of PaCO2 above the normal 40 mm Hg.
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