Normal Saline During Endotracheal Suctioning and Airway Management

Routine instillation of normal saline into an endotracheal or tracheostomy tube immediately before suctioning is generally not recommended. The current American Association for Respiratory Care (AARC) clinical practice guideline on artificial-airway suctioning states that normal saline solution should generally be avoided during suctioning because routine use has not shown a consistent clinical benefit and can cause adverse effects.

This is an important correction to older bedside practice. Saline was once commonly instilled because clinicians hoped it would loosen thick secretions, stimulate coughing, lubricate the suction catheter, or improve secretion removal. However, modern evidence does not support routine lavage for these purposes.

A 2023 systematic review and meta-analysis of mechanically ventilated adults reached a similar conclusion. Across 16 studies, normal saline instillation before endotracheal suctioning was associated with several potentially harmful effects, including decreases in oxygen saturation, longer recovery of oxygenation in some studies, changes in heart rate and blood pressure, and more coughing. The authors concluded that the harms outweighed the benefits for routine use.

This guide explains what artificial-airway suctioning is, why saline was historically used, what current evidence says, when suctioning is actually indicated, how clinicians can manage thick secretions without routine saline instillation, and what safe suctioning practice looks like in adults, children, and neonates.

What Is Endotracheal Suctioning?

Endotracheal suctioning removes secretions from an artificial airway such as an endotracheal tube or tracheostomy tube. Patients who are intubated or have a tracheostomy may be unable to clear mucus effectively because the artificial airway bypasses normal upper-airway functions and can interfere with coughing and humidification.

Suctioning can help maintain airway patency when secretions accumulate, but it is not a harmless procedure. The suction catheter and negative pressure can temporarily affect oxygenation, heart rate, blood pressure, airway pressure, comfort, and lung volume.

For that reason, modern guidance treats suctioning as an intervention performed when clinically indicated rather than as a routine task done on a fixed schedule for every patient.

When Is Suctioning Indicated?

The 2022 AARC guideline identifies several signs that can indicate a need for suctioning.

In pediatric and adult patients, relevant findings can include:

Visible secretions in the artificial airway.
Coarse or changed breath sounds suggesting retained secretions.
A sawtooth pattern on the ventilator flow waveform.
Difficulty clearing secretions with coughing.
Clinical evidence that secretions are contributing to airway obstruction.

In neonates, an acute increase in airway resistance may also suggest that suctioning is needed.

The key principle is assessment first. Suction should be performed because the patient appears to need secretion removal, not simply because a certain number of hours have passed.

Why Was Normal Saline Traditionally Instilled Before Suctioning?

Normal saline instillation became common because it appeared intuitively useful. Clinicians hoped a small volume of sterile 0.9% sodium chloride would:

Thin thick mucus.
Loosen secretions attached to the tube wall.
Stimulate a cough.
Increase the amount of mucus removed.
Lubricate the suction catheter.
Help mobilize dried secretions.

The problem is that an intervention can sound physiologically reasonable without producing a meaningful benefit in real patients.

Saline does not mix evenly through tenacious airway secretions simply because it is poured into the tube. It may remain as a liquid bolus, trigger coughing, move bacteria or biofilm, and temporarily worsen gas exchange.

What Does the AARC Guideline Say?

The AARC’s 2022 evidence-based clinical practice guideline states that normal saline solution should generally be avoided during artificial-airway suctioning.

The guideline explains that newer evidence did not overturn the earlier 2010 recommendation against routine saline use. It notes that saline instillation may be associated with adverse events such as:

Decreased oxygen saturation.
Excessive coughing.
Bronchospasm.
Tachycardia.
Dyspnea.
Increased intracranial pressure in susceptible patients.
Possible dislodgement of bacterial biofilm from the inside of the artificial airway.

The guideline therefore concludes that routine saline instillation is unnecessary.

What Did the 2023 Systematic Review Find?

A 2023 systematic review and meta-analysis published in Intensive and Critical Care Nursing evaluated the benefits and harms of normal saline instillation before endotracheal suctioning in mechanically ventilated adults.

The review included 16 studies: 13 randomized controlled trials and three quasi-experimental studies.

Across the studies, saline instillation was associated with findings that included:

Reduced oxygen saturation in some measurements.
Longer time for oxygen saturation to return to baseline.
Lower arterial pH in some studies.
Increased heart rate.
Increased systolic blood pressure.
More secretions being retrieved, which does not necessarily mean better patient outcomes.

One potentially favorable finding involved ventilator-associated pneumonia in some data, but this result has not been consistent enough to support routine saline instillation.

The reviewers concluded that normal saline instillation before suctioning had more harmful effects than benefits and recommended following current guidance against routine use.

Does Saline Actually Thin Secretions?

This is one of the most common reasons clinicians historically used saline.

However, putting a few milliliters of saline into an endotracheal tube is not the same as providing continuous humidification or changing the hydration of mucus throughout the airway. A small saline bolus does not reliably mix with or chemically thin all retained secretions.

When secretions are unusually thick, the better response is to identify why they are thick rather than automatically instilling saline before every suction event.

Possible contributing factors can include inadequate airway humidification, dehydration, infection, medication effects, prolonged mechanical ventilation, blood or debris within the airway, or accumulation of material inside the artificial tube.

What About Very Thick or Tenacious Secretions?

Thick secretions can be difficult to manage, and this is the situation most often used to justify saline.

The AARC guideline does not say that saline can never be used under any circumstance. It says routine use should generally be avoided and, if saline is ever used, it should be done sparingly and with careful consideration of potential adverse effects.

For a patient with difficult secretions, the clinical team should first evaluate other aspects of airway care, including:

Whether suctioning is actually indicated.
Whether airway humidification is appropriate.
Whether secretions are collecting inside the tube.
Whether shallow suctioning is sufficient.
Whether the patient can cough effectively.
Whether an airway-clearance strategy is needed.
Whether bronchoscopy or another intervention is indicated for an unusual obstruction.

Saline should not become a substitute for assessing the cause of secretion retention.

Should Saline Be Used in Neonates?

Routine saline instillation is not recommended simply because the patient is a neonate.

Neonatal patients are especially vulnerable to changes in oxygenation, airway resistance, and physiologic stability. The 2022 AARC guideline covers neonatal, pediatric, and adult patients and still recommends generally avoiding normal saline during suctioning.

In neonates, clinicians should also use appropriately small suction catheters and carefully controlled suction pressures because the airway diameter is extremely small.

Should Saline Be Used in Children?

The same general principle applies in pediatric patients: routine saline instillation is unnecessary.

The AARC guideline also recommends suctioning neonatal and pediatric patients on an as-needed basis rather than according to a routine schedule.

That helps minimize unnecessary procedures while still allowing secretion removal when clinical signs indicate obstruction or retention.

Should Saline Be Used in Adults?

Routine use is also discouraged in adults.

The 2023 systematic review focused specifically on mechanically ventilated adult ICU patients and concluded that routine saline instillation should be avoided because the evidence showed more harm than benefit.

Adult patients can experience significant discomfort, coughing, dyspnea, changes in oxygen saturation, and cardiovascular responses during suctioning, especially when saline is added.

Open vs. Closed Suction Systems

Artificial-airway suctioning can be performed using an open or closed system.

Open Suction

In open suction, the ventilator circuit is disconnected and a sterile catheter is inserted into the artificial airway.

AARC recommends sterile technique during open suctioning.

Closed Suction

A closed system allows suctioning through a catheter enclosed within the ventilator circuit without disconnecting the patient from the ventilator.

The AARC guideline states that both open and closed systems can be used safely and effectively to remove secretions in adults.

The choice depends on the patient, ventilator requirements, infection-control practice, equipment, and local protocol.

Why Preoxygenation Matters

Suctioning temporarily removes gas from the airway and can contribute to oxygen desaturation.

The AARC guideline recommends preoxygenation before suctioning in pediatric and adult patients.

The exact approach should follow the patient’s clinical condition, ventilator settings, and institutional protocol. The goal is to reduce the risk of clinically significant hypoxemia during and immediately after the procedure.

How Long Should Suction Be Applied?

AARC recommends limiting suction application to a maximum of approximately 15 seconds per suctioning procedure.

Longer suction times can increase the risk of:

Hypoxemia.
Airway trauma.
Cardiovascular stress.
Loss of lung volume.
Patient discomfort.

Efficient preparation matters because suctioning should accomplish secretion removal with the least physiologic disturbance possible.

Shallow vs. Deep Suctioning

AARC recommends using deep suctioning only when shallow suctioning is ineffective.

Shallow suction generally means advancing the catheter only to the length of the artificial airway rather than repeatedly pushing it deeply into the tracheobronchial tree.

Deep suctioning can increase airway trauma and discomfort and should not be the automatic technique for every suction event.

Catheter Size Matters

A suction catheter that is too large can obstruct airflow around the catheter and increase negative pressure within the airway.

The 2022 AARC guideline recommends that the catheter should occlude:

Less than 70% of the endotracheal tube lumen in neonates.
Less than 50% of the endotracheal tube lumen in pediatric and adult patients.

This allows some airflow around the catheter and helps reduce excessive pressure changes.

Recommended Suction Pressure

AARC recommends keeping suction pressure below approximately:

−120 mm Hg in neonatal and pediatric patients.
−200 mm Hg in adults.

Local protocols may use more conservative settings depending on patient age, tube size, equipment, and clinical status.

Why Suctioning Can Be Uncomfortable

Patients who are awake may experience suctioning as painful, frightening, or suffocating.

The catheter can stimulate coughing, airway irritation, and a sensation of breathlessness. Saline instillation can make the procedure even more distressing because liquid entering an artificial airway can trigger intense coughing and a sensation sometimes described as drowning.

Patient comfort should therefore be part of the clinical decision. Suctioning should be explained whenever possible, performed only when needed, and stopped if the patient develops significant instability.

Potential Complications of Artificial-Airway Suctioning

Even when performed correctly, suctioning can cause temporary complications.

These can include:

Hypoxemia.
Changes in heart rate.
Changes in blood pressure.
Bronchospasm.
Airway mucosal trauma.
Bleeding.
Increased intracranial pressure in susceptible patients.
Loss of lung volume.
Patient anxiety or pain.

The purpose of evidence-based technique is to remove necessary secretions while minimizing these risks.

Should Suctioning Be Performed on a Fixed Schedule?

Routine scheduled suctioning is increasingly discouraged when no clinical indication is present.

AARC specifically recommends as-needed suctioning rather than scheduled suctioning in neonatal and pediatric patients.

In adults, assessment remains central as well. Suctioning should respond to signs of retained secretions rather than becoming an automatic ritual.

What About Bronchoscopy for Secretion Removal?

Routine bronchoscopy solely to remove ordinary secretions is not recommended.

Bronchoscopy is more invasive and resource-intensive than standard suctioning. It may be considered when the clinical situation suggests a specific problem such as severe mucus plugging, airway obstruction, bleeding, a foreign body, or another indication that cannot be managed through routine suction.

What About Endotracheal Tube Scraping Devices?

Secretions and biofilm can accumulate along the inner wall of an endotracheal tube and increase airway resistance.

The AARC guideline states that devices designed to clear the inside of an endotracheal tube may be used when airway resistance is increased because of secretion accumulation.

This is a different strategy from pouring saline into the tube. It directly addresses material attached to the tube lumen.

Is There Ever a Role for Normal Saline?

Current evidence does not support routine saline instillation before suctioning.

The AARC guideline leaves room for rare individualized use by stating that, if saline is ever used, it should be used sparingly with careful attention to potential adverse effects.

That is very different from saying saline should be instilled whenever secretions appear thick.

Any exception should be based on a specific clinical rationale, local policy, patient response, and professional judgment—not habit.

Common Myths About Saline and Suctioning

Myth: Saline always thins mucus

A small bolus of saline does not reliably mix throughout airway mucus and has not demonstrated consistent clinical benefit.

Myth: Saline is harmless because it is “normal” saline

Normal saline is isotonic, but putting liquid directly into an artificial airway can still cause coughing, desaturation, bronchospasm, dyspnea, and other physiologic effects.

Myth: More secretions removed means better treatment

An increase in suctioned volume does not automatically translate into better oxygenation, fewer complications, or better outcomes.

Myth: Saline is required whenever secretions are thick

Thick secretions should prompt assessment of humidification, hydration, airway clearance, tube obstruction, and the underlying illness rather than automatic saline lavage.

Myth: Suctioning should happen every few hours

Modern guidance emphasizes clinical indication rather than unnecessary scheduled suctioning, especially in neonatal and pediatric patients.

A Practical Evidence-Based Suctioning Checklist

Confirm that suctioning is clinically indicated.
Explain the procedure to an awake patient when possible.
Assess oxygenation and hemodynamic stability.
Preoxygenate pediatric and adult patients according to protocol.
Choose an appropriate catheter size.
Use sterile technique for open suction.
Avoid routine normal saline instillation.
Use shallow suction first.
Apply suction briefly, generally no longer than 15 seconds.
Monitor oxygen saturation, heart rate, blood pressure, and patient tolerance.
Reassess whether the airway is clearer afterward.
Investigate persistent secretion problems instead of repeatedly escalating suction intensity.

Frequently Asked Questions

Should normal saline be instilled before every endotracheal suction?

No. The 2022 AARC guideline states that normal saline solution should generally be avoided during artificial-airway suctioning.

Does saline make suctioning more effective?

Evidence has not shown enough consistent benefit to justify routine use. A 2023 systematic review found more harmful effects than benefits overall.

Can saline lower oxygen saturation?

Yes. Several studies have reported temporary decreases in oxygen saturation or delayed recovery after saline instillation and suctioning.

What should clinicians do for thick secretions?

Assess the underlying cause, including airway humidification, hydration, infection, secretion burden, and tube obstruction. Use appropriate airway-clearance strategies rather than automatically instilling saline.

How long should each suction event last?

The AARC guideline recommends limiting suction application to a maximum of about 15 seconds per procedure.

Is deep suctioning better?

No. Deep suctioning should generally be reserved for situations in which shallow suctioning is ineffective.

Conclusion

The modern evidence-based answer is clear: normal saline should not be routinely instilled before artificial-airway suctioning. The practice remains familiar in some clinical settings, but familiarity is not the same as evidence.

Current AARC guidance recommends generally avoiding saline because routine use has not demonstrated reliable benefit and can produce adverse effects such as coughing, dyspnea, oxygen desaturation, bronchospasm, cardiovascular changes, and possible disruption of airway biofilm. A 2023 systematic review reached the same overall conclusion.

Safe suctioning begins with assessment. The airway should be suctioned when secretions or airway resistance indicate a need, using the appropriate catheter size, pressure, duration, oxygenation strategy, and depth. Thick secretions should trigger a broader airway-management assessment rather than automatic saline lavage.

This article is intended for general education and does not replace institutional protocols, respiratory-therapy guidelines, or individualized clinical judgment.