Pulmonary Aspiration

  1. Pulmonary aspiration causes chronic and/or reoccurring pulmonary disease. Aspiration is the result of gastric esophageal reflux (GER) of stomach content into the lung. The relationship between pulmonary disease and GER has been documented in the literature on children and adults
  2. What causes GER
    1. Tracheobronchial aspiration induced by asthma
    2. Pulmonary fibrosis
    3. Hiatal hernia may be a factor which can be combined with either of the other two factors
  3. Diagnostic procedures used to diagnose this disorder

    4. Esophageal Manometry
    http://www.nature.com/gimo/contents/pt1/full/gimo30.html

    1. Esophageal manometry
      1. In order to diagnose GER this procedure may be used
      2. Multiple "miniature pressure transducers" identify muscle contraction along the esophagus
      3. The pressure is then recorded over time as noted in the diagram
      4. GER would show peristalsis occurring in the opposite direction of normal swallowing
    2. Oesophageal pH monitoring and the Tuttle Test (Pediatric Gastroenterology and Clinical Nutrition by Bentley, et al.)
      1. 0.1 N of HCl is given PO and the patient's pH in the esophagus is monitored
      2. A drop in the pH level to less than 4 is an indication of GER
    3. Barium esophagram
      1. Swallowing barium during a fluoroscopy exam may visualize peristalsis in the esophagus
      2. Gastroesophageal Reflux Disease: Integrating the Barium Esophagram before and after Antireflux Surgery is an excellent article showing different abnormalities of esophageal diseases. To note: hiatal hernia, obstruction, and GER scarring can be seen
      3. Barium esophagram and the other above mentioned procedures are not very sensitive in detected GER. Why? Consider the occurrence of reflux and in trying to "catch it"
  4. Detection of Pulmonary Aspiration in adults via nuclear medicine
    1. General Comment - Following the administration of a radio-liquid drink or meal delayed imaging may identify aspiration of stomach content into the lung
    2. Consider the time of in which GER will occur and the need to imaging during different time intervals. Does NMT match this need?
    3. Procedure
      1. Before bedtime administer 3-5 mCi of 99mTcSC as a beverage
      2. Follow the radio-liquid administration an additional 30-50 mL of water is given to "wash" down any residue activity
      3. Imaging before the patient goes to bed is optional, however, imaging the morning is a requirement
      4. Camera setup (PM or AM)
        1. Collimator - LEHR
        2. Matrix - 128 or 256
        3. Acquisition - literature suggest 100k/image, however, if imaging is done immediately following dose administration a higher count density may be considered
        4. Window - 140 keV at 20%
        5. Supine imagine - ANT or POST and R-LAT images (exclude as much of the stomach as possible). Why?
      5. Imaging must be done in the morning and each image usually takes between 20-30 minutes @100k/image
      6. Results

          Normal - No activity is seen in the Lungs

        1. Case 1 - Following PM radio-liquid administration images were taken the next morning. No activity seen in the lungs, hence no pulmonary aspiration

          2. Pulmonary Aspiration Right Lobe

        2. Case 2 - These AM images indicate aspiration of the radiopharmaceutical into upper right lobe of the lung
    4. Reasons for missing the aspiration (think false negative)
      1. The patient may not GER every night or
      2. Aspiration may be cleared from the lung before the AM images are taken
    5. When should this procedure be done?
      1. Evaluate the effect of or the repair of a hiatal hernia
      2. Determine the best time to remove an endotracheal tube
      3. Determine if asthma has caused an aspiration
      4. Evaluate the need for a tracheotomy

    Information and images on the above information were attained in the following article: Evaluation of Gastro-Pulmonary Aspiration by a Radioactive Technique: Concise Communication. by Reich, et al.

    1. Another article by Boonyaprapa S, et al. addresses the utilization of pulmonary aspiration exam on the pediatric population. Information and images (below) are a summation of the this article
      1. Twenty children, for the ages of 1 month to 14 years was evaluated via scintigraphic imaging for possible pulmonary aspiration. Patients selection was based on a prior diagnosis of chronic respiratory infection. Twenty-five percent of these patients showed pulmonary activity there were due to: pneumonitis (3), chronic cough (1), and one TE fistula repair (1)
      2. Pediatric procedure (modification to the above approach)
        1. Dose - 500 μCi 99mTcSC was mixed in 60 to 100 mL of milk or formula. Older children were given 120 mL of OJ
        2. Small amount of non-radioactive fluid was given after the radio-liquid
        3. Five minutes post dose 100k images were taken of the chest/abdomen to include ANT, POST, R/L-LAT projections
        4. The same Images were repeated 4 hours post dose, as well as the following morning
        5. 57Co markers where also place on the shoulders to help with anatomical orientation
      3. Barium esophagram was also administered and positive in 2 of the 20 patients test. Both positive barium studies were positive with nuclear

        4. Positive - Right Mid-Lung

      4. The above example is positive for aspiration and was scanned at four hours post administration. This 4 month old female shows activity in the area of the right middle lobe of the lung and corresponds to pneumonitis seen on her chest x-ray

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