Endotracheal suctioning may or may not have an impact, but it does depend on what you measure!

Endotracheal suctioning is reportedly essential to maintain patency of an artificial airway in intubated and mechanically ventilated patients. However, the effectiveness of endotracheal suctioning alone to maintain airway patency is unclear. Endotracheal suctioning may also be associated with short-term physiological complications, such as lung de-recruitment and resultant hypoxemia in patients with acute lung injury.1 Factors that may determine the extent of lung de-recruitment or hypoxemia after endotracheal suctioning may include, but are not limited to, the method of suctioning (open or closed), the use of hyperoxygenation before/during the procedure, and the mode of mechanical ventilation (pressure or volume set).1,2 However, even with substantial lung volume loss during open suctioning, compared with closed suctioning, it may still be well tolerated and not result in any clinically important changes in arterial oxygenation or hemodynamics.2,3 In addition, the lung volume loss associated with closed suctioning may (counterintuitively) recover more slowly, compared to open suctioning.2 Therefore, it has been recommended that some form of lung recruitment be used after either open or closed suctioning, based on the extent of decrease in functional residual capacity after suctioning.4 What is becoming clear from the literature is that short-term changes in arterial oxygenation and hemodynamics, that may or may not be associated with endotracheal suctioning, may indicate changes in physiology (and not be related to patient outcome), but that measurements of efficacy of endotracheal suctioning are clearly lacking (artificial airway patency, airways resistance, mucus clearance). The “blind” nature of advancing the suction catheter may be one of the major limitations to the procedure, and may lead to less efficient suctioning.5 This may in part explain the potential for adverse effects of endotracheal suctioning on lung function or risk of local trauma. For example, a closed suctioning procedure where the negative pressure is applied without any contact with mucus within the airway may have the potential for more deleterious effects on lung volume loss and may also push the secretions away from the suction catheter tip.6 When the suction catheter comes into direct contact with the mucus, this may be expected to have a less deleterious effect on lung volume and also be more efficacious in terms of secretion removal, especially without any PEEP.6 Hence, the development of optical fiber ports embedded within suction catheters5 and endotracheal tubes7 allows direct visualization during airway care to optimize secretion clearance, if the devices become commercially available5 and are also viable to use.5,7 Recent recommendations for endotracheal suctioning8 advocate several key points to the procedure, including: to advance the suction catheter until resistance is met; to not apply suctioning routinely, but only as needed; to preferably use a closed suction catheter; to not use saline instillation; to pre-oxygenate; to use the shallow suctioning method; and to not apply suction pressure for more than 15 seconds. However, this clinical guidance8 seems not to be followed in clinical practice.9 The authors attribute this in part to the weak evidence to support some of the guidance.9 We may also ask ourselves why clinicians may or may not follow the American Association for Respiratory Care (AARC) guidance? Specific points of airway care in the AARC clinical practice guidelines8 merit further discussion. The AARC guidelines8 stipulate that endotracheal suctioning should be performed only when secretions are present, and not routinely (however, only followed by approximately 50% of clinicians9), and that shallow suctioning should be performed, as opposed to deep suctioning, for all intubated and mechanically ventilated patients (again, only followed by approximately 50% of clinicians9), which was based on neonatal literature. Deep suctioning is described as the insertion of a suction catheter until resistance is met, followed by withdrawal of the catheter by 1 cm before the application of negative pressure (there is no mention of the “stimulation” or assessment of a cough response to suctioning), and shallow suctioning as the insertion of a suction catheter to a pre-determined depth, usually the length of the artificial airway plus adapter.8,10 There is a preponderance of literature on airway suctioning and the various means to minimize the short-term physiological changes, such as arterial desaturation or changes in blood pressure and/or heart rate.1 However, these measures to minimize short-term physiological changes (such as arterial desaturation) may have the potential to also adversely impact on patient outcome(s). For example, if shallow suctioning were to become the stan-