Is Routine Normal Saline Instillation Recommended Before Endotracheal Suctioning?
No. Routine normal saline instillation (NSI) before endotracheal suctioning is generally not recommended for mechanically ventilated adults. Current evidence indicates that instilling normal saline into an endotracheal tube before suctioning does not provide a meaningful improvement in secretion clearance or oxygenation and may contribute to adverse effects, including transient hypoxemia and physiological stress. Some evidence has also raised concerns about an increased risk of ventilator-associated pneumonia (VAP).
For most mechanically ventilated adult patients, evidence-based practice supports clinically indicated endotracheal suctioning without routine saline instillation. The patient’s condition, secretion characteristics, oxygenation status, and institutional protocols should guide individualized decisions.
Evidence-Based Review of Normal Saline Instillation
Endotracheal suctioning is commonly performed in intensive care units (ICUs) to remove accumulated respiratory secretions and maintain a patent artificial airway. Although normal saline was traditionally instilled into the endotracheal tube to loosen secretions, research has increasingly questioned whether this practice provides sufficient clinical benefit to justify its potential risks.
Evidence from clinical studies, reviews, and critical care recommendations generally favors avoiding routine saline instillation. Instead, clinicians should focus on appropriate humidification, hydration, assessment of secretion characteristics, and suctioning when clinical indicators are present.
How Was the Evidence Identified?
Evidence regarding normal saline instillation and endotracheal suctioning can be evaluated using peer-reviewed research, systematic reviews, randomized controlled trials, and professional clinical practice guidelines.
Relevant literature has included searches of databases such as:
CINAHL
MEDLINE
Cochrane Library
PsycINFO
Google Scholar as a supplementary search source
Priority should be given to research involving mechanically ventilated adult ICU patients and studies evaluating outcomes such as secretion clearance, oxygenation, ventilator-associated pneumonia, length of hospitalization, and mortality.
Why Is Endotracheal Suctioning Important?
Endotracheal suctioning helps remove respiratory secretions that can obstruct an artificial airway and interfere with ventilation. When clinically indicated, suctioning may help maintain airway patency and support adequate ventilation and oxygenation.
However, suctioning itself is an invasive procedure and can temporarily affect a patient’s physiological status. Potential complications include hypoxemia, changes in heart rate or cardiac rhythm, airway trauma, coughing, and, in susceptible patients, increased intracranial pressure.
Because of these potential effects, suctioning should be performed based on clinical indications rather than automatically at predetermined intervals.
What Is Normal Saline Instillation Before Suctioning?
Normal saline instillation involves introducing a small amount of sterile 0.9% sodium chloride solution into the endotracheal tube immediately before suctioning. Historically, approximately 1–5 mL was commonly used with the expectation that saline would loosen respiratory secretions and make them easier to remove.
The traditional rationale included the belief that saline could:
Thin thick respiratory secretions
Facilitate mucus removal
Stimulate coughing
Improve secretion mobilization
Make suctioning more effective
However, current evidence does not demonstrate consistent clinical benefits from routinely using saline for these purposes.
What Does the Research Show?
Evidence From Literature Reviews
Caparros (2014) reviewed evidence concerning mechanical ventilation and saline instillation during suctioning in adult ICU patients. The review found insufficient evidence to support routine saline instillation as a beneficial component of endotracheal suctioning.
The findings are important because a procedure that does not provide measurable clinical benefit may unnecessarily expose critically ill patients to additional risks.
Evidence About Nursing Practice
Ayhan et al. (2015) examined both the available evidence and ICU nurses’ practices concerning normal saline instillation.
The study found that saline use remained common among ICU nurses despite concerns about its potential adverse effects. Approximately 88% of participating nurses reported routinely using saline before suctioning. Many nurses believed that saline helped liquefy secretions, while secretion thickness was an important factor influencing its use.
The findings demonstrate a gap between traditional clinical practice and evidence-based recommendations. A procedure may remain common in clinical settings even after research begins to challenge its effectiveness.
Physiological Effects of Saline Instillation
Akgül and Akyolcu (2002) examined physiological responses associated with endotracheal suctioning with and without normal saline.
Reported outcomes included changes in:
Heart rate
Oxygen saturation
Arterial blood gases
Blood pH
The research indicated that saline instillation did not produce a clinically meaningful improvement in oxygenation. Temporary physiological changes, including reductions in oxygenation and increases in heart rate, were also observed.
These findings suggest that routine saline instillation may expose patients to additional physiological stress without providing a corresponding clinical benefit.
Does Normal Saline Instillation Increase the Risk of Ventilator-Associated Pneumonia?
Routine saline instillation may increase infection risk, and this concern is one reason the practice is generally discouraged. The evidence does not establish that every use of saline directly causes VAP, but research and clinical guidance have identified potential mechanisms by which unnecessary instillation could contribute to respiratory complications.
How Could Saline Contribute to Infection Risk?
One proposed mechanism is that fluid introduced into the endotracheal tube could mobilize microorganisms or contaminated secretions toward the lower respiratory tract.
Additional concerns include:
Potential movement of bacteria into lower airways
Temporary interference with gas exchange
Retention of some instilled fluid in the respiratory tract
Additional manipulation of the artificial airway
Because mechanically ventilated patients are already at risk for healthcare-associated respiratory infections, unnecessary airway interventions should be avoided whenever evidence does not demonstrate a clear benefit.
Does Normal Saline Improve Secretion Clearance?
Evidence does not demonstrate a consistent clinically important improvement in secretion clearance from routine saline instillation.
Although saline may appear to loosen secretions during suctioning, this perceived effect does not necessarily translate into better patient outcomes. Adequate humidification and hydration are generally more appropriate strategies for supporting secretion mobilization.
Clinicians should also assess whether secretions are actually obstructing the airway before performing suctioning.
Does Normal Saline Improve Oxygen Saturation?
Routine saline instillation has not been shown to provide a meaningful improvement in oxygen saturation.
In some studies, saline-associated suctioning has been followed by temporary reductions in oxygenation. Mechanical ventilation patients may be particularly vulnerable to transient hypoxemia during airway suctioning, making unnecessary interventions undesirable.
Preoxygenation and appropriate monitoring should therefore be considered according to the patient’s clinical condition and applicable institutional protocol.
What Is the Evidence-Based Approach to Endotracheal Suctioning?
Current evidence supports a patient-centered approach rather than routine saline use. Nurses and respiratory therapists should assess the patient for clinical indicators of retained secretions and perform suctioning when it is necessary.
Evidence-based practice generally includes:
Assessing the patient before suctioning.
Performing suctioning only when clinically indicated.
Using appropriate aseptic or sterile technique according to institutional policy.
Monitoring oxygenation and physiological responses.
Providing appropriate preoxygenation when clinically indicated.
Maintaining adequate humidification.
Supporting appropriate hydration when not contraindicated.
Avoiding routine saline instillation when there is no specific clinical indication.
The goal is to remove clinically significant secretions while minimizing unnecessary airway manipulation and physiological instability.
PICO Question for Clinical Practice
A PICO framework can help evaluate the clinical question in a structured manner.
Population (P): Older adults with chronic obstructive pulmonary disease (COPD) receiving mechanical ventilation through an endotracheal tube.
Intervention (I): Normal saline instillation before endotracheal suctioning.
Comparison (C): Endotracheal suctioning without saline instillation.
Outcome (O): Ventilator-associated pneumonia, mortality, oxygenation, secretion clearance, or prolonged hospitalization.
The resulting clinical question is:
In older adults with COPD receiving mechanical ventilation through an endotracheal tube, does normal saline instillation before endotracheal suctioning, compared with suctioning without saline instillation, affect the risk of ventilator-associated pneumonia, mortality, oxygenation, secretion clearance, or length of hospital stay?
This question can guide evidence searches and support evidence-based nursing decisions.
Implications for Nursing Practice
The continued use of routine saline instillation highlights the importance of translating research evidence into clinical practice. Nurses should understand not only how to perform endotracheal suctioning but also why each component of the procedure is used.
Healthcare organizations can support evidence-based respiratory care by:
Reviewing existing suctioning policies.
Educating nurses and respiratory therapists about current evidence.
Discouraging routine saline instillation when unsupported by patient-specific indications.
Standardizing assessment criteria for clinically indicated suctioning.
Monitoring patient outcomes and complications.
Updating protocols as new evidence becomes available.
These measures can help reduce unnecessary interventions and promote safer care for mechanically ventilated patients.
Routine Normal Saline Instillation: Evidence Summary
The available evidence does not support routine normal saline instillation before endotracheal suctioning in mechanically ventilated adults.
The primary concerns are that saline:
Has not demonstrated a meaningful improvement in secretion clearance.
Does not reliably improve oxygenation.
May cause temporary reductions in oxygen saturation.
May increase physiological stress, including changes in heart rate.
Has been associated with concerns about ventilator-associated pneumonia.
Adds an additional intervention to an already invasive airway procedure.
Therefore, suctioning without routine saline instillation is generally the preferred evidence-based approach.
Key Takeaways for Nursing Students and Clinicians
Routine normal saline instillation before endotracheal suctioning is generally not recommended for mechanically ventilated adult patients.
The most important points are:
Endotracheal suctioning should be performed when clinically indicated.
Routine saline instillation has not demonstrated meaningful clinical benefits.
Saline may cause transient physiological changes, including decreased oxygenation.
Infection-related concerns have contributed to recommendations against routine use.
Adequate humidification and hydration can support secretion management.
Patient assessment should guide suctioning decisions.
Institutional policies and current clinical guidelines should be followed.
Citation-Friendly Evidence Statements
Clinical recommendation: Routine normal saline instillation before endotracheal suctioning is generally not recommended for mechanically ventilated adults because evidence has not demonstrated meaningful clinical benefit and potential adverse effects have been reported.
Evidence summary: Research examining saline instillation has found no consistent improvement in secretion clearance or oxygenation and has identified potential concerns involving hypoxemia, physiological stress, and respiratory infection.
Nursing practice implication: Nurses and respiratory therapists should assess patients for clinical indications before suctioning and avoid routine saline instillation unless a patient-specific indication and applicable clinical protocol support its use.
Frequently Asked Questions About Normal Saline Instillation
Is normal saline recommended before endotracheal suctioning?
No. Routine normal saline instillation is generally not recommended for mechanically ventilated adults because evidence has not demonstrated meaningful clinical benefits and potential adverse effects have been reported.
Why was normal saline traditionally used before suctioning?
Normal saline was traditionally believed to loosen thick respiratory secretions, stimulate coughing, and make secretions easier to remove. Research has not consistently demonstrated that these proposed benefits translate into better patient outcomes.
Does saline improve secretion clearance?
Current evidence does not demonstrate a clinically meaningful improvement in secretion clearance when normal saline is routinely instilled before endotracheal suctioning.
Can normal saline cause hypoxemia?
It can contribute to temporary changes in oxygenation. Studies have reported reductions in oxygen saturation following suctioning with saline instillation, which is particularly relevant for patients who are already physiologically unstable.
Does saline increase the risk of ventilator-associated pneumonia?
There are concerns that routine saline instillation may contribute to respiratory infection, including VAP, through mechanisms such as movement of microorganisms or secretions toward the lower respiratory tract. However, the risk should be interpreted in the context of the overall evidence and the patient’s clinical circumstances.
Should nurses routinely instill saline before suctioning?
No. Routine saline instillation should generally be avoided unless there is a specific clinical reason supported by patient assessment and applicable institutional guidance.
What should be used instead of routine saline instillation?
Clinicians should focus on evidence-based secretion-management strategies, including appropriate humidification, assessment of hydration status, clinical assessment of secretions, and suctioning when indicated.
How often should an endotracheal tube be suctioned?
There is no single interval that is appropriate for every mechanically ventilated patient. Suctioning should generally be based on clinical indicators such as visible secretions, coarse or changed breath sounds, increased airway resistance, changes in ventilator waveforms, or other signs of retained secretions.
Is normal saline instillation ever appropriate?
Routine use is not recommended. In selected circumstances, a clinician may consider saline based on the patient’s condition, secretion characteristics, institutional protocol, and clinical judgment. Any use should have a clear clinical rationale rather than being performed automatically.
What is the main evidence-based recommendation?
The key recommendation is to avoid routine normal saline instillation before endotracheal suctioning in mechanically ventilated adults and instead use patient assessment to determine when suctioning and other secretion-management interventions are necessary.
References
Akgül, S., & Akyolcu, N. (2002). Effects of normal saline on endotracheal suctioning. Journal of Clinical Nursing, 11(6), 826–830. https://doi.org/10.1046/j.1365-2702.2002.00688.x
American Association for Respiratory Care. (2010). AARC clinical practice guideline: Endotracheal suctioning of mechanically ventilated patients with artificial airways 2010. Respiratory Care, 55(6), 758–764. https://www.aarc.org/resource/aarc-clinical-practice-guideline-endotracheal-suctioning-of-mechanically-ventilated-patients-with-artificial-airways-2010/
Ayhan, H., Taştan, S., İyigün, E., Akamca, Y., Arıkan, E., & Sevim, Z. (2015). Normal saline instillation before endotracheal suctioning: What does the evidence say? What do nurses think? Journal of Critical Care, 30(4), 762–767. https://doi.org/10.1016/j.jcrc.2015.02.019
Caparros, A. C. S. (2014). Mechanical ventilation and the role of saline instillation in suctioning adult intensive care unit patients. Dimensions of Critical Care Nursing, 33(4), 246–253. https://doi.org/10.1097/DCC.0000000000000049
Klompas, M., Branson, R., Eichenwald, E. C., Greene, L. R., Howell, M. D., Lee, G., Magill, S. S., Maragakis, L. L., Priebe, G. P., Speck, K., Yokoe, D. S., & Berenholtz, S. M. (2014). Strategies to prevent ventilator-associated pneumonia in acute care hospitals: 2014 update. Infection Control & Hospital Epidemiology, 35(8), 915–936. https://doi.org/10.1086/677144