FREE TMC Exam Study Guide 2026: The Complete NBRC Walkthrough

This free TMC Exam study guide walks through the highest-yield content the TMC Exam (Therapist Multiple-Choice Examination) tests, organized by the three NBRC content sections.^[1]

It is interactive, not a wall of text: every section has worked clinical scenarios, comparison tables, labeled diagrams, and built-in flashcards — taught to the entry-level CRT and RRT standard the exam actually measures.

Read it section by section, then round out your prep with our practice questions and flashcards. The exam administers 160 questions in 3 hours (140 scored) and has two cut scores — a low cut for the CRT and a higher cut for RRT eligibility.^[1]

TMC Exam Snapshot

Section III, Initiation and Modification of Interventions, is by far the largest — about 80 of the 160 items (half the exam), followed by Section I, Patient Data Evaluation (~57), and Section II, Troubleshooting and Quality Control (~23). Weight your study toward interventions — ventilation, airways, oxygen therapy, and pharmacology — while keeping blood-gas interpretation sharp, because it threads through the whole exam.^[1]

The shares above are approximate blueprint weights of the 160 administered items; the exact item counts come from the NBRC Detailed Content Outline, so verify the current numbers on the official outline.^[1] Twenty of the 160 items are unscored pretest questions that do not affect your score, and you cannot tell which they are.

How the TMC Is Built (3 Sections)

The TMC is built from the NBRC Detailed Content Outline, which groups every question into three content sections.^[1]

Section I, Patient Data Evaluation and Recommendations, is about gathering and interpreting data — blood gases, assessment, and diagnostics. Section II, Troubleshooting and Quality Control of Devices and Infection Control, is about equipment and safety. Section III, Initiation and Modification of Interventions, is the largest and is about doing — airways, ventilation, oxygen therapy, and drug therapy.

This guide groups the three sections into eight study modules for efficient learning — all three sections are covered, just organized into related clusters (for example, the blood-gas, oxygenation, and diagnostic content of Section I becomes three focused modules).^[1] The TMC reports a pass/fail result against two cut scores; clearing the low cut earns the CRT, and clearing the high cut adds eligibility for the CSE on the path to the RRT.^[2][3]

Blood Gases & Acid–Base

Arterial blood gas interpretation is part of Section I (Patient Data Evaluation) and is one of the most testable skills on the whole exam.^[4] If you can read a gas quickly and correctly, you bank points across every section.

The 5-Step ABG Method

Interpret every gas in the same order. First the pH: below 7.35 is acidemia, above 7.45 is alkalemia. Then the PaCO2 (normal 35–45 mm Hg) and the HCO3 (normal 22–26 mEq/L).

Whichever value moves the same way as the pH disturbance is the primary cause — a respiratory problem if it is the PaCO2, a metabolic problem if it is the HCO3. Finally, check whether the other system has shifted to compensate.^[4]

The Four Acid–Base Disorders

There are four primary disorders. Respiratory acidosis (low pH, high PaCO2) comes from hypoventilation — a COPD exacerbation, oversedation, or neuromuscular weakness. Respiratory alkalosis (high pH, low PaCO2) comes from hyperventilation — anxiety, pain, pulmonary embolism, or hypoxia.

Metabolic acidosis (low pH, low HCO3) comes from diabetic ketoacidosis, lactic acidosis, or renal failure. Metabolic alkalosis (high pH, high HCO3) comes from vomiting, diuretics, or nasogastric suction.

Oxygenation, Hemoximetry & Capnography

Still in Section I, this module covers how you measure oxygenation and ventilation at the bedside — the calculations, the co-oximetry pitfalls, and the capnography waveform.^[4]

P/F Ratio & A–a Gradient

The P/F ratio (PaO2 ÷ FiO2 as a decimal) grades oxygenation and ARDS severity: under the Berlin definition (with PEEP ≥ 5 cm H2O), 200–300 is mild, 100–200 is moderate, and 100 or below is severe ARDS.^[5] For example, a PaO2 of 80 on an FiO2 of 0.80 gives a P/F of 100 (severe); a PaO2 of 90 on 0.60 gives 150 (moderate). The A–a gradient (alveolar PO2 minus arterial PaO2) widens when there is a gas-exchange problem such as V/Q mismatch or shunt, rather than simple hypoventilation.

CO-Oximetry, Pulse Ox & Capnography

Standard pulse oximetry cannot detect carboxyhemoglobin (carbon-monoxide poisoning reads a falsely normal SpO2) or methemoglobin (SpO2 stuck near 85%) — CO-oximetry is required for both. Capnography measures exhaled CO2: a normal square waveform after intubation confirms the tube is in the trachea, a rising baseline suggests rebreathing, and a sudden rise during CPR signals return of spontaneous circulation.

Pulmonary Diagnostics & Weaning

The last part of Section I: interpreting pulmonary function and the bedside numbers that decide whether a ventilated patient is ready to come off support.^[7]

Spirometry & Lung Mechanics

On spirometry, the FEV1/FVC ratio is the first fork: a value below about 0.70 with a reduced FEV1 is an obstructive pattern (asthma or COPD); a normal/high ratio with reduced volumes is a restrictive pattern. Asthma obstruction is reversible (FEV1 improves ≥12% and ≥200 mL after a bronchodilator); COPD obstruction is fixed.^[7]

On the ventilator, distinguish peak from plateau pressure: a rising peak with a stable plateau is increased airway resistance, while a rising peak with a rising plateau is decreased compliance. Auto-PEEP (air trapping) is found with an expiratory-hold maneuver.

Weaning Parameters

Know the thresholds. The rapid shallow breathing index (rate ÷ tidal volume in liters) below about 105 favors successful weaning; above 105 predicts failure (e.g., a rate of 32 with a 0.3 L tidal volume gives ~107). A maximum inspiratory pressure more negative than about −20 to −30 cm H2O indicates adequate muscle strength (−15 is inadequate), and a vital capacity of at least ~10 mL/kg supports weaning (8 mL/kg is borderline-low).^[11]

Devices, Troubleshooting & QC

This module opens Section II (Troubleshooting and Quality Control) — the smallest section (~23 items) but full of fast, recognizable points about equipment.^[1]

Oxygen Delivery Devices

The key split is low-flow vs high-flow. A low-flow device (nasal cannula, simple mask, nonrebreather) supplies less than the patient's total inspiratory demand, so the actual FiO2 varies with the breathing pattern. A high-flow device (air-entrainment/Venturi mask, high-flow nasal cannula) delivers a total flow that meets or exceeds demand and so gives a fixed, predictable FiO2.^[11]

On a nonrebreather, complete bag collapse during inspiration means the flow is too low — raise it until the bag stays partially inflated.

Alarms & Quality Control

For ventilator alarms, the rule is simple: a high-pressure alarm means obstruction or stiffness (secretions, kinked/bitten tube, bronchospasm, falling compliance, pneumothorax), and a low-pressure alarm means a leak or disconnection (circuit disconnect, underinflated cuff, loose connection). For quality control, oxygen analyzers are calibrated to room air and 100% O2 (two-point calibration), and blood-gas analyzers are monitored with a Levey-Jennings chart and Westgard rules to separate random from systematic error.

Infection Control

The rest of Section II: keeping equipment and patients safe from infection — high-yield for respiratory therapists, who perform many aerosol-generating procedures.^[10]

Spaulding & Device Reprocessing

The Spaulding classification sets the required level of reprocessing by infection risk. Critical items enter sterile tissue or the bloodstream and must be sterilized.

Semicritical items contact mucous membranes or non-intact skin and require at least high-level disinfection (a reusable laryngoscope blade is semicritical). Noncritical items touch only intact skin and need low- or intermediate-level disinfection.^[10]

Isolation Precautions

Match the precaution to the route of spread. Airborne precautions (negative-pressure room, fit-tested N95) are for pathogens in small droplet nuclei — tuberculosis, measles, varicella.^[9]

Droplet precautions (surgical mask) are for larger respiratory droplets — influenza, pertussis. Contact precautions (gown and gloves) are for spread by touch — MRSA, C. difficile.

Airway Management

Now into Section III (Initiation and Modification of Interventions) — the largest section and the heart of the exam. Airway management is the foundation: establishing, protecting, and maintaining a patent airway.^[11]

Tubes, Cuffs & Suctioning

Pick the right tube size (about an 8.0 mm internal diameter for an average adult man, 7.0–7.5 for an average woman) and keep ET cuff pressure at 20–30 cm H2O — high enough to seal, low enough to avoid tracheal mucosal ischemia (a pressure of 38 means you remove air). When suctioning a new tracheostomy, advance the catheter only to just beyond the tip of the tube. If a new tracheostomy patient suddenly becomes dyspneic and you cannot pass a catheter, remove the inner cannula first to check for a mucus plug.

Intubation & Extubation

Readiness to extubate means the patient can protect the airway (intact gag and cough) with the underlying cause of failure resolved — not just good numbers. Before extubation, a cuff-leak test with no leak when the cuff is deflated suggests laryngeal edema and a risk of post-extubation stridor (treated with racemic epinephrine). A laryngeal mask airway is a supraglottic rescue device that does not protect against aspiration the way a cuffed endotracheal tube does.

Mechanical Ventilation

Mechanical ventilation is the single highest-yield topic in Section III — modes, settings, waveforms, ARDS strategy, and weaning all live here.^[6]

Modes & Settings

Know the core modes. In assist-control (A/C), every breath — whether the patient or the ventilator triggers it — is delivered at the full set tidal volume or pressure, so it offers the most support and rests the muscles. In SIMV, mandatory breaths are synchronized with the patient's efforts and spontaneous breaths in between get only what the patient generates (often plus pressure support).

Pressure support augments each spontaneous breath with a set inspiratory pressure and cycles off when inspiratory flow falls. Set tidal volume by ideal body weight, and titrate PEEP and FiO2 together for oxygenation.

Waveforms, ARDS & Weaning

The ARDSnet lung-protective strategy uses a low tidal volume of about 6 mL/kg of ideal body weight with the plateau pressure kept below 30 cm H2O — for a 70-kg IBW patient that is roughly 420 mL.^[6] A modest rise in PaCO2 is accepted as permissive hypercapnia as long as the pH stays within the protocol limit.

To lower a high PaCO2, raise minute ventilation (rate or tidal volume); to fix oxygenation, raise PEEP/FiO2. Wean with a spontaneous breathing trial when the patient is hemodynamically stable, oxygenating on minimal support, and shows an RSBI below ~105.

Pharmacology & Airway Clearance

The rest of Section III: the drugs you deliver and the techniques that clear secretions and re-expand lung — high-yield because therapists administer them directly.^[8]

Respiratory Pharmacology

Albuterol is a short-acting beta-2 agonist that relaxes bronchial smooth muscle quickly — first-line for acute bronchospasm. Ipratropium is a short-acting anticholinergic that bronchodilates by blocking muscarinic receptors and is often combined with albuterol.

Racemic epinephrine reduces upper-airway swelling by mucosal vasoconstriction — used for croup and post-extubation stridor. Dornase alfa (a mucolytic) thins the sticky DNA-rich sputum of cystic fibrosis, and nebulized hypertonic saline draws water into the airway to improve clearance.^[8]

Airway Clearance & Lung Expansion

Postural drainage positions the affected segment uppermost so gravity drains secretions. PEP therapy and oscillatory devices (flutter valve, Acapella) splint airways open and mobilize mucus; high-frequency chest wall oscillation (the vest) helps patients who cannot tolerate manual techniques. For lung expansion, incentive spirometry has an alert, cooperative patient take slow, deep breaths, while IPPB is reserved for patients who cannot take an adequate deep breath on their own.

How to Use This Study Guide

Work through the guide one module at a time. After each one, check it off in the contents to raise your exam-readiness score, then drill the same content in our free practice questions and flashcards — active recall and timed practice are what move knowledge into exam-day performance.

• Weight your time by the blueprint. Section III (Interventions) is half the exam — ventilation, airways, oxygen therapy, and drugs come first.
• Make ABG interpretation automatic. Blood gases thread through every section; the 5-step method should be reflexive.
• Drill the calculations. Minute ventilation, P/F ratio, A–a gradient, RSBI, cylinder duration, and 6 mL/kg tidal volume show up repeatedly — practice them until they're fast.
• Learn the alarm and device rules. High vs low pressure, low-flow vs high-flow, and the cuff-pressure window are quick, reliable points.
• Know the can't-miss safety moves. Blocked trach inner cannula, post-extubation stridor, tension pneumothorax, and airborne isolation for TB recur across the exam.
• Then prove it. When a module feels solid, confirm with our practice questions — build a comfortable margin before exam day, especially for the higher (RRT) cut score.

Common clinical concepts TMC candidates study and get asked — each answered briefly and backed by an official source (NBRC, NHLBI/NIH, CDC, ARDSnet, or AARC). Tap any card to test yourself.

TMC Glossary

Key TMC terms in one place. Hover any dotted term throughout the guide for its definition; the full list is below.

TMC Exam

The Therapist Multiple-Choice Examination — the entry-level credentialing exam from the NBRC that earns the CRT credential at the low cut score and unlocks eligibility for the Clinical Simulation Examination toward RRT at the high cut score.

NBRC

The National Board for Respiratory Care — the body that develops and administers the TMC Exam, the Clinical Simulation Examination, and the CRT and RRT credentials.

CRT

Certified Respiratory Therapist — the entry-level respiratory-care credential earned by meeting the low cut score on the TMC Exam; many states require it for licensure.

RRT

Registered Respiratory Therapist — the advanced respiratory-care credential earned by meeting the high TMC cut score and then passing the Clinical Simulation Examination (CSE).

CSE

Clinical Simulation Examination — the NBRC's scenario-based second exam; passing it (after a high-cut TMC) is required to earn the RRT credential.

cut score

The minimum number of correct scored items needed to pass; the TMC has two — a low cut score for the CRT and a higher cut score that adds eligibility for the CSE.

respiratory acidosis

An acid-base disorder with a low pH and a high PaCO2 caused by hypoventilation (e.g., COPD, oversedation), so carbon dioxide accumulates in the blood.

respiratory alkalosis

An acid-base disorder with a high pH and a low PaCO2 caused by hyperventilation (e.g., anxiety, pain, pulmonary embolism, hypoxia), blowing off carbon dioxide.

metabolic acidosis

An acid-base disorder with a low pH and a low HCO3, as in diabetic ketoacidosis, lactic acidosis, renal failure, or diarrhea.

metabolic alkalosis

An acid-base disorder with a high pH and a high HCO3, as from vomiting, diuretics, or nasogastric suction.

P/F ratio

The PaO2 divided by the FiO2 (as a decimal); under the Berlin definition it grades ARDS severity — 200–300 mild, 100–200 moderate, and 100 or below severe.

A-a gradient

The alveolar–arterial oxygen gradient, the difference between alveolar PO2 and arterial PaO2; a widened gradient indicates a gas-exchange (V/Q mismatch, shunt, diffusion) problem.

carboxyhemoglobin

Hemoglobin bound to carbon monoxide; it cannot carry oxygen and is missed by standard pulse oximetry, so CO-oximetry is needed to detect carbon-monoxide poisoning.

methemoglobin

Hemoglobin whose iron is in the ferric (Fe3+) state and cannot bind oxygen; it causes cyanosis with a pulse oximeter often reading near 85% and is detected by CO-oximetry.

capnography

Continuous measurement of exhaled carbon dioxide; a normal square waveform confirms tracheal tube placement, and a sudden rise during CPR signals return of spontaneous circulation.

FEV1/FVC ratio

The fraction of forced vital capacity exhaled in the first second; below about 0.70 defines an obstructive pattern (asthma or COPD).

RSBI

The rapid shallow breathing index — respiratory rate divided by tidal volume in liters; a value below about 105 predicts successful weaning, above 105 predicts failure.

plateau pressure

The ventilator pressure measured during an inspiratory hold (no flow); it reflects lung compliance and is kept below 30 cm H2O to limit ventilator-induced lung injury.

auto-PEEP

Intrinsic PEEP — gas trapped in the alveoli when exhalation is incomplete before the next breath (common in COPD/asthma); detected with an expiratory-hold maneuver.

ARDS

Acute respiratory distress syndrome — diffuse alveolar injury with refractory hypoxemia; managed with low-tidal-volume (≈6 mL/kg) lung-protective ventilation per the ARDSnet protocol.

PEEP

Positive end-expiratory pressure — pressure held in the lungs at the end of exhalation to keep alveoli open and improve oxygenation.

Spaulding classification

A system that sorts devices by infection risk — critical (sterilize), semicritical (high-level disinfection), and noncritical (low/intermediate disinfection).

airborne precautions

Isolation for pathogens carried in small droplet nuclei (tuberculosis, measles, varicella): a negative-pressure room and a fit-tested N95 respirator.

ET cuff pressure

The pressure in an endotracheal tube cuff, kept at 20–30 cm H2O — high enough to seal but low enough to avoid tracheal mucosal ischemia.

albuterol

A short-acting beta-2 agonist that rapidly relaxes bronchial smooth muscle; first-line for acute bronchospasm such as an asthma exacerbation.

ipratropium

A short-acting anticholinergic bronchodilator that blocks muscarinic receptors; slower onset than albuterol and often combined with it.

TMC Study Guide FAQ

References

1. 1.National Board for Respiratory Care (NBRC). “Therapist Multiple-Choice Examination — Detailed Content Outline.” NBRC. ↑
2. 2.National Board for Respiratory Care (NBRC). “Certified Respiratory Therapist (CRT).” NBRC. ↑
3. 3.National Board for Respiratory Care (NBRC). “Registered Respiratory Therapist (RRT).” NBRC. ↑
4. 4.National Heart, Lung, and Blood Institute (NHLBI). “Respiratory Failure.” nhlbi.nih.gov. ↑
5. 5.National Heart, Lung, and Blood Institute (NHLBI). “ARDS (Acute Respiratory Distress Syndrome).” nhlbi.nih.gov. ↑
6. 6.ARDS Network (ARDSnet) / NHLBI. “ARDSnet Ventilator Protocol.” ardsnet.org. ↑
7. 7.National Heart, Lung, and Blood Institute (NHLBI). “COPD.” nhlbi.nih.gov. ↑
8. 8.National Heart, Lung, and Blood Institute (NHLBI). “Asthma.” nhlbi.nih.gov. ↑
9. 9.Centers for Disease Control and Prevention (CDC). “Tuberculosis Infection Control in Healthcare Settings.” cdc.gov. ↑
10. 10.Centers for Disease Control and Prevention (CDC). “Isolation Precautions / Disinfection & Sterilization.” cdc.gov. ↑
11. 11.American Association for Respiratory Care (AARC). “Clinical Practice Guidelines.” aarc.org. ↑

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