Should Saline Go Down the Tube? A PICO Question on Normal Saline Instillation Before Endotracheal Suctioning in Ventilated Adults
[Student Name]
University of Phoenix
NSG/302: Professional Contemporary Nursing Role and Practice
Week 4 Assignment
[Instructor Name]
[Date]
The unit and its practices are a composite written for a model paper.
On the night shift of my unit, a small bottle of normal saline sits beside every ventilated patient's suction setup, and several experienced nurses instill 3 to 5 mL into the endotracheal tube before they suction. Newer nurses learned it from them, and some believe it loosens thick secretions. Others were taught in school never to do it. When two nurses disagreed at the bedside last month, neither could name the evidence for their position. This paper turns that disagreement into a PICO question, describes the search it would drive and summarizes what the evidence shows.
The Clinical Problem
Suctioning clears secretions from the airway of a patient who cannot cough through an endotracheal tube. It also carries risks: a drop in oxygen saturation, airway trauma, cardiac arrhythmias and the introduction of bacteria into the lower airway. The question of saline matters because it could either help, by thinning secretions and triggering a cough, or harm, by pushing bacteria from the tube's biofilm deeper into the lungs and lowering oxygen saturation. Ventilator-associated pneumonia remains one of the most serious infections in intensive care, so even a small effect in either direction is worth knowing.
The PICO Question
Population (P): adults receiving mechanical ventilation through an endotracheal tube in an intensive care unit.
Intervention (I): instillation of normal saline into the endotracheal tube before suctioning.
Comparison (C): suctioning without saline instillation.
Outcome (O): ventilator-associated pneumonia, with oxygen saturation after suctioning as a secondary outcome.
The complete question is: In adults receiving mechanical ventilation in an intensive care unit, does normal saline instillation before endotracheal suctioning, compared with suctioning without saline, affect the rate of ventilator-associated pneumonia and oxygen saturation after suctioning?
The question includes a comparison and outcomes that can be measured, so it could be answered by trials that compare the two practices. It does not include a time element, but ventilator-associated pneumonia is usually defined as pneumonia arising more than 48 hours after intubation, which sets an implied time frame.
The Search Strategy
I would search CINAHL Complete and MEDLINE Complete through the university library, since both index critical care nursing and medical research. The search terms come directly from the PICO elements: "normal saline" OR "saline instillation" OR "sodium chloride" combined with "suction*" and with "endotracheal" OR "intubat*" OR "mechanical ventilation." Adding "pneumonia, ventilator-associated" as a subject heading would focus the results on the main outcome. I would limit results to adults and to the last 15 years, and then check for older landmark trials cited by newer reviews. A clinical practice guideline and a systematic review would be the most useful sources, followed by randomized trials.
What the Evidence Shows
The American Association for Respiratory Care (2010), in its clinical practice guideline on suctioning, recommends against routine instillation of normal saline before endotracheal suctioning. The guideline based this on evidence that saline does not reliably thin secretions and can lower oxygen saturation after suctioning.
Caruso et al. (2009) reported a different finding. In a randomized trial of 262 adults who needed mechanical ventilation for more than 72 hours in the intensive care unit of a cancer hospital, instilling 8 mL of saline before suctioning was associated with fewer cases of ventilator-associated pneumonia confirmed by quantitative culture of bronchoalveolar lavage fluid, 10.8% compared with 23.5% in the group without saline. Clinically suspected pneumonia, atelectasis and tube occlusion did not differ between the groups. Because the trial was done in one center with a specific population, its results may not apply to every intensive care unit.
Wang et al. (2017) combined five randomized trials with 337 patients in a meta-analysis that looked at the physiological effects of saline. Oxygen saturation was significantly higher in the groups without saline five minutes after suctioning, while heart rate and blood pressure did not differ. The authors concluded that saline instillation offers no benefit and lowers oxygen saturation, but they also judged the methodological quality of the included trials to be low and called for larger trials.
Taken together, the evidence does not support using saline routinely to loosen secretions, and it shows a small but real cost in oxygenation just after suctioning. One well-designed trial suggests saline may lower culture-confirmed pneumonia in patients ventilated for several days, but a single trial in one population is not enough to recommend the practice for everyone.
Applying the Evidence to Our Patients
Evidence has to be judged against the patients it will be used on, and ours differ from those in the studies. Most patients on our unit are ventilated for less than a day after heart surgery, while the patients in the Caruso et al. (2009) trial were ventilated for more than three days, long enough for pneumonia to develop. The possible benefit on pneumonia therefore matters little for the majority of our patients, while the drop in oxygen saturation shown by Wang et al. (2017) applies to every patient who is suctioned. The small group of our patients who stay on the ventilator for several days, often after complications, look more like the patients in the trial, and they are the group in which the question is still open. Nurses should also consider what the habit was meant to fix. Thick secretions are usually a sign of inadequate humidification or dehydration, and treating the cause is more reliable than adding fluid to the airway.
Recommendation for Practice
Based on this evidence, I would recommend that our unit stop routine saline instillation, in line with the AARC guideline, and address thick secretions through adequate humidification, hydration and closed suction systems. I would also recommend that the practice council review the question once more after new trials are published, because the pneumonia finding from one trial deserves to be confirmed or refuted. Most importantly, the unit should have one written practice so that the decision is based on evidence rather than on which nurse is working that night.
Conclusion
A disagreement at the bedside became a PICO question that can be searched and answered. The current evidence recommends against routine saline instillation before suctioning, while leaving open whether it could reduce pneumonia in some patients. Week 5 will look at evidence-based practice as a QSEN competency, using a unit practice change as the example.
References
American Association for Respiratory Care. (2010). AARC clinical practice guidelines: Endotracheal suctioning of mechanically ventilated patients with artificial airways 2010. Respiratory Care, 55(6), 758-764. https://doi.org/10.4187/respcare.10550758
Caruso, P., Denari, S., Ruiz, S. A. L., Demarzo, S. E., & Deheinzelin, D. (2009). Saline instillation before tracheal suctioning decreases the incidence of ventilator-associated pneumonia. Critical Care Medicine, 37(1), 32-38. https://doi.org/10.1097/CCM.0b013e3181930026
Wang, C.-H., Tsai, J.-C., Chen, S.-F., Su, C.-L., Chen, L., Lin, C.-C., & Tam, K.-W. (2017). Normal saline instillation before suctioning: A meta-analysis of randomized controlled trials. Australian Critical Care, 30(5), 260-265. https://doi.org/10.1016/j.aucc.2016.11.001
How this NSG 302 Week 4 example is structured
Public listings for NSG/302 Week 4 describe developing a PICO question about best practices for suctioning, including whether saline instillation during suctioning is acceptable. The paper follows the order a PICO assignment is graded in: the clinical problem, the question with each element labeled, the search, what the evidence shows and the recommendation for practice. Students search this week as NSG 302 Week 4, NSG302 Wk 4 or NSG/302 Wk 4; all three are the same assignment.
NSG/302 Week 4 questions, answered
What does NSG/302 Week 4 usually ask for?
Public listings describe developing a PICO question on a suctioning practice, such as whether instilling normal saline during suctioning is acceptable, and using it to find and summarize evidence.
What do the letters in PICO stand for?
Population, intervention, comparison and outcome. Some courses add T for time, making it PICOT. Each element should be specific enough to become a search term.
Is saline instillation before suctioning recommended?
Guidance from the American Association for Respiratory Care advises against routine saline instillation before suctioning, and a meta-analysis found lower oxygen saturation after suctioning with saline. One trial suggested fewer pneumonias with saline, so the question is not fully closed.
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