Respiratory Therapist

Purpose

Breathing is the one bodily function that buys minutes, not hours, when it fails. A respiratory therapist exists because the airway and lungs sit at the center of every crisis — the asthmatic who can't move air, the COPD patient retaining CO2, the septic patient whose lungs have stiffened. The RT's job is to manage gas exchange when the body can't: open airways, titrate oxygen, run and wean the ventilators that breathe for people who can't, and read the blood gas that tells the truth the monitor can't. The discipline lives in the narrow band between too little support and too much.

Core Mission

Keep gas exchange adequate — enough oxygen in, enough CO2 out — using the least support the patient needs, while protecting the lungs from the very machines that are saving them.

Primary Responsibilities

The visible work is running machines; the actual work is continuous physiological judgment under time pressure. An RT assesses respiratory status, delivers therapy, and manages the airway across the hospital. On a given shift that means titrating oxygen while watching for CO2 narcosis in the COPD retainer; managing mechanical ventilation, including lung-protective settings for ARDS; drawing and interpreting arterial blood gases to guide every adjustment; running spontaneous breathing trials and the weaning protocol; delivering bronchodilators; assisting intubation; responding to every code as the airway expert; and running gas exchange on ECMO. Underneath it is relentless reassessment.

Guiding Principles

• Least support that works. Every cmH2O of pressure and every percent of FiO2 above what's needed does harm. Support is a debt; pay it down as fast as the patient allows.
• The ABG doesn't lie; the monitor can. Pulse ox and end-tidal are trends; the arterial blood gas is the truth. When the picture doesn't fit, draw a gas.
• Protect the lung from the ventilator. The machine that saves the patient can shred the alveoli. Low tidal volumes, controlled plateau pressures, minimal driving pressure — non-negotiable in injured lungs.
• Oxygen is a drug with a dose and a danger. In the chronic CO2 retainer, too much oxygen suppresses the drive to breathe and can kill. Titrate to a target SpO2.
• Wean early, but not recklessly. Every extra vent day adds pneumonia and weakness; a failed premature extubation is worse than waiting.
• The airway is the first priority, always. A comes before B and C; if you can't move air, nothing else matters. The direction a number moves is the diagnosis.

Mental Models

• The four-step ABG read. pH (acidemia or alkalemia?), then PaCO2 (respiratory), then HCO3 (metabolic), then compensation and whether it's acute or chronic. A pH 7.30 with PaCO2 70 and high HCO3 is a chronic respiratory acidosis with metabolic compensation — a baseline COPD retainer, not a crisis.
• Oxygenation vs. ventilation as two separate problems. Oxygenation is PaO2/FiO2 and the A-a gradient — a parenchyma/shunt problem fixed with FiO2 and PEEP. Ventilation is PaCO2 — fixed with rate and tidal volume.
• Lung-protective ventilation. Tidal volume ~6 mL/kg of ideal (not actual) body weight, plateau pressure under 30 cmH2O, low driving pressure — the ARDSNet logic that a smaller breath permitting some hypercapnia beats a big breath that barotraumatizes the lung.
• The PEEP/FiO2 ladder. Oxygenation has two levers; climb them together, recruiting alveoli with PEEP to keep FiO2 non-toxic.
• Weaning readiness as a checklist, not a hunch. Cause improving, oxygenating on low support, hemodynamically stable, awake enough to protect the airway — then an SBT, judged by the RSBI (f/Vt under ~105 predicts success).
• The hypoxic drive trap. In some chronic retainers, raising oxygen reduces respiratory drive and worsens hypercapnia; titrate to 88-92% and watch the CO2, don't saturate to 100%.

First Principles

• You have minutes, not hours, when gas exchange fails — speed of correct action is itself a clinical skill.
• Every form of support carries its own injury; the art is the minimum dose.
• A ventilator does not heal lungs — it buys time for the disease to be treated. Never confuse support with cure.

Questions Experts Constantly Ask

• Is this an oxygenation problem or a ventilation problem — which knob does it need?
• Is this acidosis acute or chronic, and is the patient compensating or decompensating?
• What's the plateau and driving pressure — am I hurting the lung to save it?
• Can this patient come off support today? Have I screened for an SBT?
• Am I over-oxygenating this COPD patient and blunting the drive to breathe?
• Is the patient awake and strong enough to protect the airway if I pull the tube?
• Is the underlying cause actually improving, or am I just masking it?
• Does this number fit the patient in front of me, or do I need a gas?

Decision Frameworks

• Escalation ladder of oxygen support. Nasal cannula to high-flow to non-invasive ventilation (BiPAP/CPAP) to intubation. A hypercapnic COPD exacerbation often belongs on BiPAP; intubating it prematurely starts a hard weaning clock.
• Intubate vs. trial non-invasive. Weigh mental status, secretion burden, trajectory, and reversibility. NIV buys time for reversible problems; a patient who can't protect the airway needs the tube.
• The daily SBT decision. Screen readiness every morning. If the patient passes, run a spontaneous breathing trial on minimal support and judge by RSBI, tolerance, and gas exchange; pass it and clear the other criteria, extubate.
• Lung-protective titration in ARDS. Set 6 mL/kg IBW, keep plateau under 30, climb the PEEP/FiO2 table, and permit hypercapnia as long as the pH tolerates it.

Workflow

1. Get the picture. Vitals, SpO2, work of breathing, breath sounds, mental status, history, and current support before touching a setting.
2. Draw and read the gas. Establish whether the problem is oxygenation, ventilation, or both, and whether acid-base is acute or chronic.
3. Choose the level of support. Match the escalation ladder to the trajectory; pick mode and settings for the physiology, not the protocol default.
4. Set lung-protective parameters. Tidal volume to IBW, appropriate PEEP/FiO2, watch plateau and driving pressure.
5. Reassess relentlessly. Re-gas after changes, watch trends, adjust to the least support that maintains targets.
6. Screen for liberation daily. Sedation interruption, readiness screen, SBT, RSBI; extubate when criteria are met.
7. Hand off and document. Communicate the trajectory and plan; the next RT inherits the whole picture.

Common Tradeoffs

• Weaning aggressively vs. premature extubation. Pull too early and you risk a crash reintubation; wait too long and you accrue pneumonia and diaphragm weakness.
• Oxygenation vs. oxygen toxicity and CO2 narcosis. High FiO2 fixes hypoxia but damages lung tissue and in retainers suppresses the drive.
• Tidal volume: comfort vs. lung protection. Bigger breaths feel better and blow off CO2 but injure the lung; permissive hypercapnia trades higher CO2 for a safer lung.
• NIV vs. intubation. Non-invasive support avoids the tube but fails dangerously if the patient is too sick or obtunded.
• Sedation vs. synchrony. Deeper sedation improves vent tolerance but delays weaning and clouds airway assessment.

Rules of Thumb

• Tidal volume is set on ideal body weight, never actual.
• Plateau pressure over 30 means the lung is taking a beating.
• In the COPD retainer, target SpO2 88-92%.
• If the saturation and the patient disagree, believe the patient and draw a gas.
• Oxygenation is PEEP and FiO2; ventilation is rate and volume — don't cross the wires.
• RSBI under 105: probably ready; over 105, wait.
• On a sudden desat, check the patient and circuit before the monitor — DOPE: Displacement, Obstruction, Pneumothorax, Equipment.
• Wean FiO2 before PEEP; toxicity is the bigger enemy.

Failure Modes

• Over-oxygenating the retainer to a "reassuring" 100%, suppressing drive toward CO2 narcosis.
• Volutrauma/barotrauma from tidal volumes set to actual body weight or unchecked plateau.
• Treating the number, not the patient — chasing a normal CO2 in a chronic retainer.
• Sedation creep and missed daily SBTs that keep a ready patient tubed days too long.
• Premature extubation without confirming airway protection.
• Trusting the monitor in a crisis instead of laying hands on the patient and circuit.

Anti-patterns

• Set-and-forget ventilation — settings left unchanged as the physiology moves.
• Crossing oxygenation and ventilation levers — turning up FiO2 for a high CO2, or rate for a low PaO2.
• Protocol on autopilot — the default mode and settings without reading the specific lungs.
• More oxygen is always better — saturating everyone to 100% regardless of CO2.
• Ignoring driving pressure while fixating on tidal volume and plateau.
• Weaning by feel instead of a screen, an SBT, and an RSBI.

Vocabulary

• ABG — arterial blood gas: pH, PaCO2, PaO2, HCO3, base excess; the ground truth of gas exchange.
• P/F ratio — PaO2 divided by FiO2; an oxygenation index (under 300 = ARDS, under 100 = severe).
• A-a gradient — difference between alveolar and arterial oxygen; localizes the cause of hypoxia.
• PEEP — positive end-expiratory pressure; keeps alveoli open at end-exhalation.
• FiO2 — fraction of inspired oxygen, 0.21 (room air) to 1.0.
• Tidal volume (Vt) — the volume of one breath; ~6 mL/kg IBW in lung-protective ventilation.
• Plateau pressure — alveolar pressure at end-inspiration; keep under 30 cmH2O.
• SBT — spontaneous breathing trial, the test of weaning readiness.
• RSBI — rapid shallow breathing index (frequency/tidal volume); under ~105 predicts weaning success.
• AC / SIMV / PSV — ventilator modes: assist-control, synchronized intermittent mandatory ventilation, pressure support.
• Permissive hypercapnia — tolerating a high CO2 to keep the breath small and the lung safe.

Tools

• Mechanical ventilators — the core instrument; fluency in modes, alarms, and waveforms is the trade.
• ABG analyzer — for the blood gas that drives every adjustment.
• Pulse oximeter and capnography — continuous trends in oxygenation and exhaled CO2.
• High-flow nasal cannula, CPAP/BiPAP units — the non-invasive rungs of the support ladder.
• Intubation kit and bag-valve-mask — for airway emergencies and assisting intubation.
• Nebulizers and metered-dose inhalers — for inhaled medication delivery.
• ECMO circuit — for the sickest lungs and hearts, where the RT manages extracorporeal gas exchange.

Collaboration

The RT is the respiratory authority on a team that leans on it in the highest-stakes moments. Intensivists order the broad plan, but the RT recommends modes, settings, and weaning decisions and usually knows the ventilator best. Emergency physicians and anesthesiologists rely on the RT in codes. Bedside nurses are the continuous eyes who call when the saturation drops or the patient fights the vent. Pharmacists co-manage the inhaled and sedation medications. The recurring friction is autonomy: the RT often sees the right ventilator move before the order catches up, and good teams build protocols that let the RT act.

Ethics

The RT works at the literal edge of life support, which puts end-of-life decisions in the daily routine. Withdrawing the ventilator from a dying patient — a terminal extubation — is among the most ethically weighted acts in medicine, and the RT performs it, managing air hunger so the patient is comfortable. Honesty about prognosis matters: families ask the RT at the bedside whether the machine is helping, and both false hope and false despair are harms. The discipline also carries a duty to defend the least-support principle against the urge to over-treat — aggressive support is not always kindness, and sometimes it only prolongs dying.

Scenarios

The COPD patient turning blue — and the trap of fixing it wrong. A 64-year-old with end-stage COPD arrives somnolent, SpO2 78%, on a non-rebreather cranked by the paramedics. The RT draws a gas: pH 7.26, PaCO2 92, HCO3 38, PaO2 60 — an acute-on-chronic respiratory acidosis. She's a chronic retainer who has decompensated, and the high oxygen has blunted her drive further. The fix is not more oxygen; it's ventilation. The RT dials FiO2 down to target 88-92% and starts BiPAP to blow off CO2 and rest her tiring muscles. Within an hour her CO2 falls and her mental status clears, and she avoids the tube.

ARDS and the small breath that saves the lung. A 50-year-old, 80 kg, septic ARDS, P/F ratio 90, intubated. A junior instinct sets 8 mL/kg of his actual weight — 640 mL. The RT recalculates on ideal body weight (height puts IBW near 70 kg) and sets 6 mL/kg, about 420 mL; plateau reads 28, acceptable. To oxygenate, the RT climbs the PEEP/FiO2 ladder rather than just turning up oxygen. CO2 drifts to 55 at pH 7.31 — permissive hypercapnia, accepted, because protecting the lung beats a textbook-normal gas.

The morning weaning decision. A post-op patient has been ventilated four days; the pneumonia that put him there is resolving. The RT runs the morning screen: oxygenating on FiO2 0.40 and PEEP 5, hemodynamically stable, awake and following commands after the sedation hold. He clears it, so the RT runs an SBT on minimal pressure support. The RSBI comes back at 70, well under 105, and he tolerates 30 minutes without distress or rising CO2; cough is strong, secretions manageable. The RT recommends extubation — liberation earned by the screen, the SBT, and the airway check, not assumed.

Related Occupations

The RT is defined by ownership of the airway and gas exchange. Registered nurses are the closest daily partners, sharing the bedside and trading off respiratory monitoring. Emergency physicians and anesthesiologists rely on the RT's airway skills in codes and intubations. Paramedics manage the same problems in the field. Cardiologists overlap where heart failure floods the lungs. Physical therapists collaborate on pulmonary rehab and mobilizing ventilated patients. Pharmacists co-manage the medications that shape ventilation.

References

• Egan's Fundamentals of Respiratory Care — the field's standard text
• The Ventilator Book — William Owens
• Marino's The ICU Book — Paul Marino
• ARDSNet ARMA trial — lung-protective ventilation evidence base
• AARC (American Association for Respiratory Care) Clinical Practice Guidelines