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Published, English language studies were identified by searching Medline (1966–98), EMBASE/Excerpta Medica (1974–96), and CINAHL (1982–97) using the search terms trachea, pharynx, tracheostomy, suction, artificial airway, inflation, and endotracheal, and by searching the Cochrane Library. Bibliographies of retrieved studies were reviewed.
Studies were included if they were randomised controlled trials (RCTs), randomised or non-randomised crossover studies, cohort studies, case series, or animal studies (only used to identify adverse effects of suctioning; not used in the development of recommendations).
Data were extracted on study type and date, allocation methods, patient inclusion and exclusion criteria, adequacy of follow up, comparison of baseline characteristics, specific interventions, outcome measures, and results. No formal tool was used to assess quality of individual studies.
161 RCTs, non-randomised controlled trials, randomised or non-randomised crossover studies, and cohort studies were included. Meta-analysis was not done because of differences among studies. Selected results of RCTs and randomised crossover studies of adult patients are summarised in the table⇓.
Several techniques have beneficial effects during suctioning of ventilated and intubated patients.
Suctioning intubated patients aids in removing secretions and maintaining a patent airway, while promoting optimal ventilation and oxygenation. The development of guidelines by Brooks et al supports clinical decision making by taking into consideration both the benefits and complications associated with the procedure. Recommendations for preoxygenation, hyperoxygenation, hyperinflation plus method of delivery, swivel adaptor use, and others were reported.
The authors noted that insufficient evidence exists regarding several aspects of suctioning. For example, instillation of normal saline is thought to thin and loosen secretions, lubricate the suction catheter, and stimulate coughing.1 However, normal saline instillation may also cause a decrease in oxygen saturation2 and dislodge more bacteria in endotracheal tubes than use of suction catheters alone.3 Brooks et al highlight the paucity of scientific evidence to support saline instillation.
Subsequent guidelines need to address the evidence for the heated humidification of the inspired gas, monitoring of patient hydration status, and use of mucolytic agents or nebulisers. Patients receiving 100% humidity heated to core temperature (37°C) are reported to be at the optimal level for mucosal function, maximising mucous clearance.4
Brooks et al provide recommendations useful to healthcare providers engaged in the care of ventilated and intubated patients. These guidelines for suctioning can be applied to all ventilated patients, including those who are on volume control, synchronised intermittent mandatory ventilation, or pressure support. However, guidelines do not pre-empt sound clinical decision making. Clinicians still need to pay close attention to patient oxygenation levels, haemodynamic status, and responses to suctioning, especially if patients are unstable or have thick and tenacious secretions.
Source of funding: College of Physiotherapists of Ontario.
For correspondence: Dr D Brooks, University of Toronto, Toronto, Ontario, Canada.
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