Saline and Suctioning: Are You In or Out?

Endotracheal suctioning is one of the most common procedures performed in patients with artificial airways (American Association for Respiratory Care [AARC] Clinical Practice Guidelines [CPG], 2010). Suctioning is performed to maintain a clear airway and optimize respiratory function. It is carried out when a patient with an artificial airway cannot independently eliminate pulmonary secretions.

There are two methods of endotracheal suctioning, namely open and closed suctioning. Open suctioning requires the disconnection of the patient from the ventilator, while closed suctioning involves the attachment of a sterile in-line suctioning device to the ventilator circuit, to facilitate oxygenation during the procedure. The latter is the preferred method in most procedures.

Suctioning methods can be further categorized according to the depth of insertion of the suction catheter.  Shallow suctioning is the insertion of the catheter up to a pre-determined depth, usually the length of the artificial airway plus the adapter (Koeppel, R, 2006). Deep suctioning is the continuous insertion of the suction catheter until resistance is met, and the subsequent withdrawal of the catheter by 1 cm before the application of suction pressure (AARC CPG, 2010). According to several prominent studies, deep suctioning has not been shown to offer any superior benefits over shallow suctioning, and may even be associated with more adverse events.

Saline instillation during endotracheal suctioning is an ongoing controversial topic of debate. Instillation of saline refers to the administration of aliquots of saline directly into the trachea via an artificial airway (AARC CPG, 2010). It was traditionally hypothesized that the normal saline instillation would thin out and loosen secretions to facilitate their removal, and ultimately improve the patient's oxygenation status. However, there is insufficient evidence to support this hypothesis, and the latest research findings indicate that these saline instillations are unlikely to provide any benefit, and may in fact be harmful (Branson, R.D, 2007).

In a descriptive, observational study published in the American Journal of Critical Care in 1999, 35 patients were assigned to two research groups after coronary artery bypass grafting. One group had 5 ml of normal saline instilled at the start of endotracheal tube suctioning; the other group had the same endotracheal tube suctioning procedure without the use of saline. Data on mixed venous oxygen saturation were recorded at 1-minute intervals for a 5-minute baseline period and then throughout the suctioning procedure until mixed venous oxygen saturation returned to baseline levels. Results indicated that the time required for mixed venous oxygen saturation to return to baseline values after suctioning was an average of 3.78 minutes longer when saline was used. This study concluded that the instillation of normal saline before endotracheal suctioning had an adverse effect on oxygenation as indicated by mixed venous oxygen saturation.

All nurses who perform suction must have received approved training and demonstrated competence under supervision. They should ensure that their knowledge and skills are maintained and updated regularly. Always check your facility’s policies and procedures to verify unit-specific protocols, policies and guidelines.

American Association for Respiratory Care (AARC) Clinical Practice Guidelines: Endotracheal Suctioning. Respiratory Care, June 2010. Volume 55, No. 6.

Branson, RD (2007). Secretion Management in the Mechanically-Ventilated Patient. Respiratory Care, 2007;52 (100:1328-1347).

Kinloch, D (1999). Instillation of Normal Saline During Endotracheal Suctioning: Effects on Mixed Venous Oxygen Saturation. American Journal of Critical Care, Vol 8, Issue 4, 231-240.

Koeppel, R (2006). Endotracheal Tube Suctioning in the Newborn: A Review of the Literature. Newborn Infant Nurse Review, 2006;6;94-99.