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Efficacy of dye-stained enteral formula in detecting pulmonary aspiration
Norma A Metheny1, Thomas E Dahms, Barbara J Stewart
1School of Nursing, Saint Louis University, St. Louis, MO 63104, USA. methenna@slu.edu
Insights
This animal study found that FD&C Blue No. 1 dye is not reliable for detecting repeated pulmonary aspirations, as its visibility decreased over time and was hindered by blood in secretions.
Area of Science:
- Gastroenterology
- Pulmonology
- Clinical Diagnostics
Background:
- Pulmonary aspiration is a significant risk in patients with altered consciousness or gastrointestinal dysfunction.
- Detecting aspiration is crucial for timely intervention and preventing complications like pneumonia.
- FD&C Blue No. 1 dye has been proposed as a marker for detecting tracheobronchial aspiration.
Purpose of the Study:
- To evaluate the effectiveness of FD&C Blue No. 1 dye in detecting repeated small-volume pulmonary aspirations in an animal model.
- To compare the visibility of two different concentrations of FD&C Blue No. 1 dye in tracheobronchial secretions.
Main Methods:
- An animal model (New Zealand white rabbits) was used to simulate pulmonary aspiration.
- A mixture of human gastric juice and enteral formula, stained with FD&C Blue No. 1 dye (0.8 or 1.5 mL/L), was instilled intratracheally.
- Suctioned tracheobronchial secretions were analyzed for visible dye and blood over a 6-hour period following three aspiration events.
Main Results:
- Dye was visible in 46.3% of secretions; dye concentration did not significantly impact visibility.
- Blood in secretions (42.2%) interfered with dye detection.
- Dye visibility decreased significantly after repeated aspiration events, even in the absence of blood.
Conclusions:
- The FD&C Blue No. 1 dye method is not reliable for detecting repeated small-volume pulmonary aspirations.
- A lower dye concentration (0.8 mL/L) appears as effective as a higher concentration (1.5 mL/L) if the method is used.
- Further research may be needed to identify more reliable methods for aspiration detection.
Study Objective:
To determine the extent to which a mixture of human gastric juice and enteral formula stained with two concentrations of FD&C Blue No. 1 food dye (0.8 and 1.5 mL/L) is visible in suctioned tracheobronchial secretions following three forced small-volume pulmonary aspirations over a 6-h period in an animal model.
Design:
Experimental 2 x 3 repeated measures.
Setting:
Animal laboratory and an acute care hospital.
Participants:
Ninety New Zealand white rabbits weighing approximately 3 kg each, and 90 acutely ill adults who furnished gastric juice.
Interventions:
A mixture of human gastric juice and enteral formula stained with 0.8 or 1.5 mL of dye per liter was instilled intratracheally over a 30-min period into anesthetized intubated animals at baseline, 2 h, and 4 h. A total of 0.4 mL/kg of the mixture was instilled at each session. Ninety minutes after each instillation, suctioned secretions were examined for visible dye and blood.
Measurements And Results:
Dye was visible in 46.3% of the secretions (125 of 270). The concentration of dye had no significant effect on dye visibility. Blood that was present in 114 of 270 of the secretions (42.2%) interfered with dye visibility in all but two secretions. For reasons unknown, even in the absence of blood, dye visibility decreased from 90.2% (55 of 61 secretions) after the first aspiration event to only 61% (25 of 41 secretions) after the third aspiration event.
Conclusions:
Findings from this animal model study do not support the use of the dye method to detect repeated small-volume aspirations. For clinicians who choose to use the dye method in selected situations, it appears that a dye concentration of 0.8 mL/L may be as effective in detecting aspiration as a 1.5 mL/L concentration.