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Robert E. St. John is an adjunct clinical instructor at St. Louis University School of Nursing in St. Louis, Mo. He is Director of Clinical Research for Oximetry and Critical Care Systems at Nellcor Puritan Bennett, a unit of Tyco Healthcare.
Airway management is an important priority for any critically ill patient. Airway adjuncts used to help maintain a patent airway may include relatively simple devices such as an oral (Figure 1
) or nasopharyngeal airway (Figure 2), while more complex airway support may require placement of either an endotracheal (ET) or tracheostomy tube. Artificial airways can be used for both short-and long-term airway management.
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Q: What are some key strategies to prevent complications associated with artificial airways?
Suctioning
Suctioning frequency should always be based on clinical need (Table 1) and not on a fixed schedule, in order to decrease the potential of complications associated with suctioning (eg, hypoxemia, arrhythmias, increased mean arterial blood pressure and intracranial pressure, tracheal tissue damage).3–7
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The amount or level of suction pressure selected should be limited to the level needed (follow manufacturer suggestions for closed suction systems) to effectively remove secretions and for as short a time as possible to minimize the potential for adverse effects.
Suction application during catheter withdrawal can be done with either a continuous or intermittent technique.11 Both techniques have the potential to produce damage to tracheal tissue.
Selection of an appropriately sized suction catheter for a given tube inner lumen diameter is also important to avoid complications during the suctioning procedure (Table 2). The suction catheter outer diameter should not exceed one half the internal diameter of the ET or tracheostomy tube.2
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Both open (single use, disposable suction catheters) and closed suction catheter systems (in-line systems for mechanically ventilated patients) are acceptable, but the use of closed suction catheter systems may avoid some of the infection control issues and other complications associated with open suction techniques.5–7
Use of a modified ET tube with a dedicated lumen for the purpose of subglottic or above-the-cuff suctioning to remove pooled secretions has been shown to reduce or delay the onset of ventilator-associated pneumonia.14,15
Normal saline instillation should not be routinely performed as part of the suctioning procedure.16,17 Normal saline instillation does not thin or liquify secretions, may cause arterial oxygen saturation decreases,18–21 and may contribute to lower airway contamination due to bacterial contamination.22
Cuff Inflation and Pressure Monitoring
There is no recommendation on a preferred method for cuff inflation. The minimal leak technique and the minimal occlusive volume technique are both acceptable methods for cuff inflation (Table 3).2
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Routine deflation of tube cuffs is no longer indicated because it does not significantly affect lateral tracheal wall pressure and may increase the risk of aspiration and hypoxemia.
Portable chest radiographs, while useful for assessing position of the ET tube cuff, are of limited value in determining the safety of cuff inflation pressure.25
Q: When should tracheotomy be considered in a patient who is intubated with an ET tube?
The optimal time frame for transitioning from ET to tracheostomy tube during the treatment of respiratory failure is controversial.26 Patients with ET tubes are at risk of developing a number of complications such as ulceration of the nasal and oral mucosa, sinusitis, and laryngeal damage.1,27 Transitioning from an ET to a tracheostomy tube helps to prevent some of these complications but places the patient at risk for complications of tracheostomy, including hemorrhage and infection. Many clinicians suggest that consideration for tracheotomy should occur following 10 to 14 days of translaryngeal intubation, but the exact timing should be individualized based on careful assessment of patient’s airway management needs.26 Early tracheotomy may be indicated when prolonged artificial airway support is anticipated or when patient comfort benefits may be realized. In addition, tracheotomy may provide the patient greater options with regard to speech and communication, as well as feeding and nutrition.
Q: How do you effectively monitor for pulmonary aspiration of enteral formula in tube-fed patients with either an ET or tracheostomy tube in place?
Pulmonary aspiration of enteral formulas is a serious potential complication associated with tube feedings.30 Clinical monitoring and early detection of aspiration episodes are therefore of obvious importance, particularly in those patients who are intubated and receiving mechanical ventilation. The two most commonly employed methods for detection of aspiration at the bedside are adding blue dye or food coloring to the feeding formulas and testing tracheobronchial secretions for glucose content.28–30
Those clinicians who advocate the dye/food coloring method believe that coloring enteral formulas facilitates visualization of gastric contents that have been aspirated into the tracheobronchial tree, resulting in discoloration of suctioned tracheal secretions. Proponents of the glucose testing method base their opinion on the premise that tracheobronchial secretions normally contain little glucose (less than 5 mg glucose per dL) and therefore, higher than expected amounts of glucose in tracheal aspirates would be an indication of aspiration of glucose-rich formula.36
Potential problems with using the dye/food coloring method include confusion regarding the amount of dye to use, discoloration of body fluids and tissues, risk of infection from contaminated dye, interference with tests for occult blood, and potential allergic reactions.30–33 A few clinical studies have indicated that the sensitivity of the dye method is low.28,34 Limitations of the glucose oxidase reagent strip method include false-positive results with bloody tracheal aspirates due to glucose in the blood, low sensitivity when low-glucose formulas are used, and questionable specificity.29,30,35 More scientific information supports use of the glucose method over the dye method. It should be noted, however, that both methods have their own unique limitations and this area is in need of further research.
If the dye method is chosen, the nurse should use as little dye as possible to allow for visualization of dye-stained tracheobronchial secretions if an aspiration episode occurs.30 Moreover, the coloring agent used should be sterile. When the glucose method is used, consider the concentration of glucose in the formula feeding. If the levels are low (less than 200 mg/dL), remember that there is no scientific data to confirm if using this method is effective.29 Lastly, recognize that only bloodless tracheal secretions should be tested for glucose to avoid false positive readings. Routine assessment for visual or occult presence of blood is advised. Regardless of the detection method used, findings should always be confirmed by other physical assessment and diagnostic investigation.
Measures to prevent aspiration are an important part of airway management. Elevating the head of the bed reduces the frequency and severity of pulmonary aspiration. Withholding enteral feeding when gastric residual volumes are high is also important in the prevention of regurgitation and pulmonary aspiration.13,30
Optimizing airway function in the critically ill patient requires a detailed understanding of airway devices used as well as current airway management practices and trends. Utilizing research-based protocols as part of a hospital-based quality improvement program is one important way in which critical care nurses and others may contribute to improving overall patient care and outcomes. In this way, a primary goal of reducing or avoiding potential complications associated with airway devices and diagnostic/therapeutic procedures may be achieved. 9
This article is based on the protocol Airway Management by Elizabeth Henneman, Kathleen Ellstrom, Robert E. St. John. It was taken from the Care of the Mechanically Ventilated Patient series of AACN’s Protocols for Practice. Protocols can be obtained from AACN, 101 Columbia, Aliso Viejo, CA 92656-1491, (800) 899-AACN, (949) 362-2000. $11, AACN members; $14, nonmembers.
Note
This article was first published in Critical Care Nurse August 1999.
To purchase reprints, contact The InnoVision Group, 101 Columbia, Aliso Viejo, CA 92656. Phone, (800) 809-2273 or (949) 362-2050 (ext 532); fax, (949) 362-2049; e-mail, reprints{at}aacn.org.
Q: How do you effectively monitor for pulmonary aspiration of enteral formula in tube-fed patients with either an ET or tracheostomy tube in place?
A: As previously discussed in the original Protocols for Practice on Airway Management and prior article, pulmonary aspiration of enteral formulas is a serious potential complication associated with tube feedings. In the past, the 2 most commonly employed methods for detection of aspiration at the bedside included adding blue dye to the feeding formulas and testing tracheobronchial secretions for glucose content.1–3 Recent reports indicate that the use of FD&C Blue dye No. 1 has the potential for harm.4,5 In addition, the dye method lacks adequate sensitivity to detect repeated small-volume aspirations.6 For clinicians who choose to use blue dye in isolated situations, a concentration of 0.8 mL of dye per liter of formula has been shown to be as effective as is a concentration twice this amount.6 If the dye method is used, it is important to ensure that the dye is sterile to avoid contamination of the enteral formula to which it is added.7 Using glucose oxidase reagent strips to monitor for aspiration is problematic because this method lacks adequate specificity.8,9 Because of this, the glucose method is no longer recommended for detecting aspiration.10
At present, there are no adequate bedside methods for detecting small-volume aspirations in tube-fed patients. Therefore, the emphasis should be placed on preventing aspiration whenever possible.
References
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