Guide — Aerosol Therapy & Pharmacology
Inhaled Pulmonary Vasodilators & Specialty Aerosols
Some inhaled drugs are not about routine bronchodilation at all — they are delivered for a specific ICU problem: opening the pulmonary vasculature, putting antibiotic where the infection lives, or shrinking a swollen upper airway. This guide covers the specialty aerosols the RT sets up and monitors, with the cautions that come with each.
9 min read · Aerosol Therapy & Pharmacology
Written by Apex Respiratory Editorial Team
Educational use only. This material supports respiratory therapy education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional protocols, or physician orders. Always follow facility policies and current provider orders, and verify calculations independently before clinical use.
Overview
These are the inhaled agents delivered for specific ICU problems rather than routine bronchodilation. Where an albuterol treatment relaxes airway smooth muscle, these agents dilate the pulmonary vasculature, concentrate antibiotic in the airway, or shrink a swollen upper airway — each for a defined indication.
For the RT, the work is in the setup and the monitoring: maintaining a continuous nebulization, watching the specific toxicities of inhaled nitric oxide, weaning rather than abruptly stopping a pulmonary vasodilator, and catching bronchospasm or rebound edema when it appears.
Key Concepts
Each specialty aerosol pairs a distinct mechanism with a distinct indication and a distinct caution — the three things to keep straight for each agent.
| Agent | Action | Key Point |
|---|---|---|
| Inhaled nitric oxide (iNO) | Selective pulmonary vasodilation that improves V/Q matching and oxygenation | Refractory hypoxemia, pulmonary hypertension, and persistent pulmonary hypertension of the newborn. Monitor methemoglobin and NO₂; do not stop abruptly (rebound pulmonary hypertension). |
| Inhaled prostacyclins (epoprostenol, iloprost) | Selective pulmonary vasodilation by continuous nebulization | An alternative to inhaled nitric oxide. |
| Inhaled antibiotics (tobramycin, aztreonam, colistin) | High local airway concentration with less systemic toxicity | Chronic airway infection in cystic fibrosis and bronchiectasis. |
| Racemic epinephrine | Mucosal vasoconstriction that reduces airway-wall edema | Post-extubation stridor and croup. Watch for rebound edema and monitor heart rate. |
- “Selective” is the key word for the vasodilators. Because inhaled nitric oxide and the prostacyclins reach only ventilated lung, they dilate vessels where gas is exchanged and improve V/Q matching without the systemic hypotension of an intravenous vasodilator.
- Inhaled antibiotics trade systemic exposure for local concentration. Delivering tobramycin, aztreonam, or colistin straight to the airway puts a high concentration where the chronic infection lives while sparing the rest of the body the toxicity.
- Racemic epinephrine works on the airway wall, not the muscle. Its mucosal vasoconstriction shrinks edema in the upper airway, which is why it treats stridor and croup rather than lower-airway bronchospasm.
Assessment & Findings
- Improved oxygenation after a pulmonary vasodilator. A rise in oxygenation after starting inhaled nitric oxide or a prostacyclin is the expected response.
- Reduced stridor after racemic epinephrine. Quieting of stridor signals that the airway-wall edema has shrunk.
- New wheeze after an inhaled antibiotic. A wheeze that appears after a dose signals bronchospasm — the adverse effect to watch for with inhaled antibiotics.
RT Priorities / Interventions
- Maintain continuous nebulization for prostacyclins. Inhaled prostacyclins (epoprostenol, iloprost) are delivered by continuous nebulization — set it up and keep it running without interruption.
- Monitor inhaled nitric oxide closely. Track methemoglobin and NO₂, and watch for rebound pulmonary hypertension when weaning — never stop it abruptly.
- Deliver racemic epinephrine and watch the heart rate. Give it for stridor or croup, and monitor the heart rate during and after the treatment.
- Give inhaled antibiotics per protocol. Administer tobramycin, aztreonam, or colistin per protocol and watch for bronchospasm.
Common Pitfalls
- Stopping inhaled nitric oxide abruptly. Sudden withdrawal can trigger rebound pulmonary hypertension — it must be weaned, not switched off.
- Not monitoring methemoglobin during iNO. Skipping methemoglobin surveillance misses a real toxicity of the therapy.
- Discharging too soon after racemic epinephrine. The effect can wear off and edema can return, so sending the patient out too early risks rebound edema.
- Missing inhaled-antibiotic bronchospasm. Failing to listen for a new wheeze after a dose lets bronchospasm go unrecognized.
Board Exam Pearls
- Inhaled nitric oxide is a selective pulmonary vasodilator that improves oxygenation — monitor methemoglobin and never stop it abruptly.
- Inhaled prostacyclins are an inhaled nitric oxide alternative.
- Racemic epinephrine treats post-extubation stridor and croup by vasoconstriction.
- Inhaled antibiotics treat chronic cystic fibrosis and bronchiectasis infection.
FAQ
How does inhaled nitric oxide improve oxygenation?
Inhaled nitric oxide is a selective pulmonary vasodilator. Because it is delivered as a gas to ventilated lung, it dilates the vessels of regions that are being ventilated and shifts blood flow toward them — improving ventilation/perfusion (V/Q) matching and therefore oxygenation. It is used for refractory hypoxemia, pulmonary hypertension, and persistent pulmonary hypertension of the newborn.
What must be monitored during inhaled nitric oxide therapy?
Monitor methemoglobin and nitrogen dioxide (NO₂), since nitric oxide can oxidize hemoglobin to methemoglobin and form toxic NO₂. Just as important, inhaled nitric oxide must not be stopped abruptly — sudden withdrawal can cause rebound pulmonary hypertension, so it is weaned, and the patient is watched for rebound during weaning.
When is racemic epinephrine used?
Racemic epinephrine is given for post-extubation stridor and for croup. Its mechanism is mucosal vasoconstriction, which reduces airway-wall edema and opens the narrowed upper airway. Because the effect can wear off and edema can return, watch for rebound edema and monitor the heart rate during and after dosing.
Why are some antibiotics given by inhalation?
Inhaled antibiotics — tobramycin, aztreonam, and colistin — deliver a high antibiotic concentration directly to the airway while limiting systemic exposure and toxicity. That makes them suited to chronic airway infection in cystic fibrosis and bronchiectasis. They can provoke bronchospasm, so the RT gives them per protocol and watches for new wheeze.
Put it to work
A pulmonary vasodilator is judged by the oxygenation it buys. Run a PaO₂ and FiO₂ through the calculator to quantify the P/F ratio before and after — the number the therapy is meant to move.
Open the P/F Ratio Calculator →Related Resources
Sources
- Kacmarek RM, Stoller JK, Heuer AJ. Egan's Fundamentals of Respiratory Care. 12th ed. Elsevier; 2021.
- Gardenhire DS. Rau's Respiratory Care Pharmacology. 10th ed. Elsevier; 2019.