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Quizzes > Health & Medicine > Human Anatomy & Medicine

Take the ABG Interpretation & Ventilator Settings Quiz

Ready to tackle the ventilator settings quiz and ace ABG analysis?

Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art illustration showing ABG interpretation quiz elements with ventilator settings icons on teal background

Calling all respiratory therapists, critical care nurses, and med students: can you ace our ABG Interpretation Quiz? This free, engaging arterial blood gas quiz is crafted to test your analysis skills and ventilator settings decision-making. Tackle acid - base balance scenarios in our Ventilator Settings Quiz section, diagnose imbalances accurately, and learn practical tips. Reinforce with abg practice questions and finalize with the ABG Interpretation Quiz. You'll review ABG analysis, mechanical ventilation settings, and get instant feedback to uncover knowledge gaps. Ready to demonstrate your expertise? Take the quiz now!

What is the normal arterial blood pH range in healthy adults?
7.35 - 7.45
7.25 - 7.35
7.20 - 7.30
7.45 - 7.55
The normal arterial pH range reflects tightly regulated acid - base balance. Values below 7.35 indicate acidemia and above 7.45 alkalemia. Thus, 7.35 - 7.45 is considered normal in healthy adults. NCBI ABG Reference
What is the normal arterial PaCO2 range?
45 - 55 mmHg
30 - 40 mmHg
25 - 35 mmHg
35 - 45 mmHg
Arterial carbon dioxide tension (PaCO2) normally ranges from 35 to 45 mmHg, reflecting adequate ventilation. Values above this can indicate hypoventilation whereas lower values suggest hyperventilation. Proper assessment of PaCO2 is key in ABG interpretation. LITFL ABG Normal Values
What is the normal arterial bicarbonate (HCO3 - ) concentration?
24 - 28 mEq/L
22 - 26 mEq/L
16 - 20 mEq/L
18 - 22 mEq/L
Serum bicarbonate (HCO3 - ) normally ranges between 22 and 26 mEq/L, representing the metabolic component of acid - base balance. Values below suggest metabolic acidosis and above indicate metabolic alkalosis. Accurate HCO3 - measurement assists with diagnosing compensation. NCBI ABG Reference
An ABG shows pH 7.50, PaCO2 30 mmHg, HCO3 - 22 mEq/L. What is the primary acid - base disorder?
Metabolic alkalosis
Respiratory acidosis
Metabolic acidosis
Respiratory alkalosis
The elevated pH (>7.45) and reduced PaCO2 (<35 mmHg) indicate respiratory alkalosis. HCO3 - is near normal, suggesting acute respiratory alkalosis without significant metabolic compensation. Primary disturbance is alveolar hyperventilation. LITFL Respiratory Alkalosis
What is the primary goal of applying positive end-expiratory pressure (PEEP)?
Treat hypercapnia
Reduce tidal volume
Improve oxygenation by recruiting alveoli
Correct metabolic acidosis
PEEP maintains positive pressure at end-expiration to prevent alveolar collapse and improve functional residual capacity. This improves oxygenation, especially in conditions like ARDS. PEEP is not primarily used for CO2 removal. ATS PEEP Review
What does FiO2 stand for in mechanical ventilation?
First inspired oxygen
Fraction of inspired oxygen
Functional inspiratory O2
Fractional inspiratory output
FiO2 refers to the fraction or percentage of oxygen in the gas mixture delivered to the patient. It ranges from 0.21 (room air) to 1.0 (100% O2). It directly influences arterial oxygenation. NCBI Ventilator Settings
Which ventilator mode delivers a preset tidal volume and respiratory rate regardless of patient effort?
Assist-Control (AC) ventilation
SIMV
Pressure support ventilation
CPAP
In AC mode, every breath (whether patient-triggered or machine-triggered) is delivered at a preset tidal volume and rate. Pressure support and SIMV allow spontaneous breaths without mandatory volume delivery. CPAP provides continuous baseline pressure only. NCBI Ventilator Modes
What is the main purpose of pressure support ventilation (PSV)?
Measure lung compliance
Deliver mandatory tidal volume
Control respiratory rate
Augment spontaneous breaths with preset pressure
Pressure support ventilation assists patient-initiated breaths by supplying a preset level of inspiratory pressure, reducing work of breathing. It does not set rate or tidal volume directly. It's used for weaning and improving comfort. ATS PSV Overview
An ABG shows pH 7.30, PaCO2 50 mmHg, HCO3 - 24 mEq/L. What is the primary disorder?
Acute respiratory acidosis
Metabolic acidosis
Metabolic alkalosis
Chronic respiratory acidosis
A low pH (<7.35) with elevated PaCO2 (>45 mmHg) and normal HCO3 - indicates acute respiratory acidosis. There has been insufficient time for renal compensation, thus HCO3 - remains normal. LITFL Respiratory Acidosis
An ABG shows pH 7.25, PaCO2 40 mmHg, HCO3 - 18 mEq/L. What is the primary disorder?
Respiratory alkalosis
Metabolic alkalosis
Metabolic acidosis
Respiratory acidosis
A low pH with normal PaCO2 and low HCO3 - indicates primary metabolic acidosis. The respiratory system may compensate by hyperventilating later, but PaCO2 here is normal, showing absence of compensation. LITFL Metabolic Acidosis
How much does HCO3 - rise acutely for every 10 mmHg increase in PaCO2 during acute respiratory acidosis?
1 mEq/L
0.5 mEq/L
4 mEq/L
3 mEq/L
In acute respiratory acidosis, HCO3 - increases by approximately 1 mEq/L for every 10 mmHg rise in PaCO2. Chronic respiratory acidosis sees about 3 - 4 mEq/L increase. This reflects renal compensation timing. NCBI Compensation Rules
According to ARDSnet protocol, what tidal volume is recommended per kg of predicted body weight?
10 mL/kg
8 mL/kg
4 mL/kg
6 mL/kg
The ARDSnet low tidal volume strategy recommends 6 mL/kg of predicted body weight to reduce ventilator-induced lung injury. Higher volumes correlate with increased barotrauma. NEJM ARDSnet Trial
What plateau pressure should be kept below to minimize risk of barotrauma?
20 cm H2O
30 cm H2O
40 cm H2O
50 cm H2O
Plateau pressures should be kept below 30 cm H2O to minimize alveolar overdistension and barotrauma. Higher pressures correlate with increased ventilator-associated lung injury. ATS Ventilator Guidelines
Which inspiratory-to-expiratory (I:E) ratio is commonly used for obstructive lung disease?
2:1
1:2
1:3 or higher
1:1
Patients with obstructive disease require prolonged expiration to avoid air trapping, so an I:E ratio of at least 1:3 or higher is used. Shorter expiratory times risk dynamic hyperinflation. NCBI Ventilator Strategies
Which change is most effective to improve oxygenation without raising tidal volume?
Decrease FiO2
Increase respiratory rate
Increase PEEP
Increase pressure support
Increasing PEEP recruits alveoli and improves oxygenation without increasing tidal volume, thereby minimizing lung injury. Raising rate affects CO2, not oxygenation. FiO2 needs to be increased, not decreased, to improve oxygenation. NCBI PEEP Effects
In SIMV mode, what allows a patient to take spontaneous breaths?
Preset tidal volume every time
Patient triggers with no mandatory delivery
Fixed respiratory rate only
Pressure control breaths only
SIMV provides mandatory breaths at set intervals while allowing patient-initiated spontaneous breaths between these intervals without mandatory volume delivery. It supports weaning. NCBI SIMV Overview
An ABG shows pH 7.40, PaCO2 60 mmHg, HCO3 - 36 mEq/L. What best describes this acid - base status?
Metabolic alkalosis
Acute respiratory acidosis
Mixed disorder
Fully compensated chronic respiratory acidosis
Normal pH with elevated PaCO2 and elevated HCO3 - indicates a fully compensated chronic respiratory acidosis. The kidneys have increased HCO3 - to normalize pH. Acute cases lack such compensation. LITFL Compensation
An ABG shows pH 7.25, PaCO2 28 mmHg, HCO3 - 12 mEq/L. Which mixed disorder is present?
Fully compensated acidosis
Mixed respiratory acidosis and alkalosis
Respiratory acidosis with metabolic alkalosis
Metabolic acidosis with respiratory alkalosis
Low pH and low HCO3 - indicates metabolic acidosis, while low PaCO2 shows respiratory alkalosis. Both contribute, confirming a mixed metabolic acidosis and respiratory alkalosis. LITFL Mixed Disorders
How do you calculate the alveolar - arterial (A - a) gradient at sea level on room air?
PAO2 = FiO2 × 713 - PaCO2; A - a = PaO2 - PAO2
PAO2 = 150 - (PaCO2/0.8); A - a = PAO2 - PaO2
PAO2 = 760 - PaCO2; A - a = PAO2 + PaO2
PAO2 = 760 - (PaCO2/0.8); A - a = PaO2 - PAO2
The alveolar gas equation at sea level on room air: PAO2 = 150 - (PaCO2/0.8). The gradient is PAO2 minus measured PaO2, reflecting gas exchange efficiency. Normal A - a is <15 mmHg. LITFL A - a Gradient
What is permissive hypercapnia?
Using high tidal volumes and low rates
Early extubation to reduce CO2 retention
Hyperventilating to lower PaCO2 aggressively
Allowing elevated PaCO2 to minimize ventilator-induced lung injury
Permissive hypercapnia accepts higher PaCO2 values by using low tidal volumes and pressure limits to reduce ventilator-induced lung injury. It's common in ARDS management. Patients tolerate mild acidosis if hemodynamically stable. ATS Permissive Hypercapnia
An increase in physiologic dead space ventilation will have what effect on PaCO2 if minute ventilation remains constant?
PaCO2 decreases
PaCO2 remains unchanged
PaCO2 becomes zero
PaCO2 increases
Increased dead space means a larger fraction of each breath does not participate in gas exchange, reducing effective alveolar ventilation. If minute ventilation is unchanged, PaCO2 will rise. LITFL Dead Space
Which Rapid Shallow Breathing Index (RSBI) threshold suggests readiness for weaning?
RSBI > 120 breaths/min/L
RSBI < 60 breaths/min/L
RSBI > 150 breaths/min/L
RSBI < 105 breaths/min/L
An RSBI (respiratory rate/tidal volume) less than 105 breaths/min/L predicts successful weaning. Higher values indicate rapid, shallow breathing and poor weaning prognosis. NCBI Weaning Criteria
On a pressure - volume loop, what does 'beaking' indicate?
Overdistension of alveoli at high pressures
Auto-PEEP presence
Complete alveolar collapse
Normal compliance
Beaking appears as a plateau at the upper right of the loop, indicating alveolar overdistension at high pressures. It warns of potential barotrauma. Adjustments to lower tidal volume or pressure may be needed. LITFL PV Loop
An ABG shows pH 7.50, PaCO2 60 mmHg, HCO3 - 38 mEq/L. What is the most likely combination?
Chronic respiratory acidosis with metabolic alkalosis
Primary metabolic alkalosis only
Respiratory acidosis with acute renal compensation
Acute respiratory alkalosis
pH is alkalemic with elevated PaCO2, indicating respiratory acidosis, but high HCO3 - suggests renal compensation plus a primary metabolic alkalosis. The combination yields an overall alkalemia. LITFL Mixed Disorders
In metabolic acidosis, how do you estimate expected respiratory compensation?
PaCO2 remains unchanged
Respiratory rate increases to lower PaCO2 by 1.2 × HCO3 - decrease
PaCO2 rises by 1.2 mmHg per 1 mEq/L HCO3 - drop
PaCO2 falls by 0.6 mmHg per 1 mEq/L HCO3 - drop
Winter's formula estimates compensation: expected PaCO2 = 1.5 × HCO3 - + 8 ±2 mmHg. This equates to roughly a 1.2 mmHg PaCO2 decrease per 1 mEq/L drop in HCO3 - . It assesses appropriate respiratory response. LITFL Winter's Formula
Which setting is unique to Airway Pressure Release Ventilation (APRV)?
I:E ratio fixed at 1:2
Two levels of continuous positive airway pressure (Phigh and Plow)
Mandatory tidal volume setting
Spontaneous breaths disabled
APRV alternates between two continuous positive airway pressure levels (Phigh and Plow) allowing spontaneous breathing throughout. It differs from conventional modes by time cycling rather than volume or pressure cycles alone. ATS APRV Overview
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Study Outcomes

  1. Analyze ABG Values -

    Interpret arterial blood gas components including pH, PaCO₂, PaO₂, and HCO₃❻ to accurately assess a patient's respiratory and metabolic status.

  2. Identify Acid-Base Imbalances -

    Classify and differentiate between respiratory and metabolic acidosis or alkalosis based on ABG results.

  3. Correlate ABG Findings with Clinical Scenarios -

    Apply ABG analysis to real-world patient cases to determine underlying pathophysiology and guide treatment decisions.

  4. Adjust Mechanical Ventilation Settings -

    Recommend appropriate ventilator adjustments such as tidal volume, respiratory rate, and FiO₂ based on ABG interpretation.

  5. Evaluate Ventilator Parameters -

    Assess key mechanical ventilation settings including PEEP, inspiratory pressure, and I:E ratio to optimize gas exchange.

  6. Strengthen Critical Care Decision-Making -

    Integrate ABG interpretation and ventilator settings knowledge to make confident, evidence-based clinical decisions.

Cheat Sheet

  1. Normal ABG Values & Mnemonic -

    Review the standard arterial blood gas reference ranges: pH 7.35 - 7.45, PaCO₂ 35 - 45 mmHg, HCO₃❻ 22 - 26 mEq/L, and PaO₂ 80 - 100 mmHg. Use the ROME mnemonic (Respiratory Opposite, Metabolic Equal) to remember that pH and PaCO₂ move in opposite directions in respiratory disorders but pH and HCO₃❻ move together in metabolic conditions (Upshaw & Roberts, 2019).

  2. Henderson-Hasselbalch Equation Basics -

    Master the Henderson-Hasselbalch equation: pH = 6.1 + log([HCO₃❻]/(0.03 × PaCO₂)). This formula underpins ABG analysis and helps calculate expected compensations - practice by plugging in sample values like HCO₃❻ 24 mEq/L and PaCO₂ 40 mmHg to confirm a normal pH of ~7.40 (Kraut & Madias, 2018).

  3. Distinguishing Primary vs. Mixed Disorders -

    Learn to identify primary acid-base disorders (acidosis or alkalosis) and recognize when mixed disorders are present - look for pH trends outside expected compensation limits. For example, in a chronic respiratory acidosis with PaCO₂ of 60 mmHg, HCO₃❻ should rise by ~4 mEq/L; larger deviations suggest a mixed process (Johns Hopkins Medicine, 2020).

  4. Alveolar Gas Equation & A - a Gradient -

    Calculate PAO₂ using PAO₂ = FiO₂ × (Patm − PH₂O) − (PaCO₂/R) to assess oxygenation; a normal A - a gradient is 5 - 15 mmHg in young adults. Checking the A - a gradient helps distinguish hypoventilation from V/Q mismatch - vital skills for your Arterial Blood Gas Quiz and real-world practice (ATS Clinical Practice, 2017).

  5. Key Ventilator Settings & Adjustments -

    Get comfortable setting tidal volume (6 - 8 mL/kg ideal body weight), respiratory rate, FiO₂, and PEEP on your mechanical ventilator. In a Ventilator Settings Quiz scenario, if pH is 7.25 with PaCO₂ of 55 mmHg, increase minute ventilation by raising RR or tidal volume - boost your confidence in the Mechanical Ventilation Settings Quiz!

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