Extra Topic 1.5 -- Aspiration

Question 1

What are the risk factors for aspiration pneumonitis?

Answer 1

Aspiration can lead to –

• pneumonitis,
• pneumonia, and
• acute respiratory distress syndrome (ARDS).

Risk factors for aspiration include –

• obesity,
• delayed gastric emptying (i.e.
  
  • pain,
  • acute abdomen,
  • cirrhosis,
  • chronic alcohol abuse,
  • autonomic neuropathy),
• pregnancy,
• neurologic dysphagia,
• bowel obstruction,
• disruption of the gastroesophageal junction,
• extremes of age, and
• a history of gastroesophageal reflux.

The risk of developing pneumonitis following aspiration depends on – the volume and pH of the aspirated content.

While unproven, it is believed that patients with a gastric volume > 25 mL and a gastric fluid pH < 2.5 are at increased risk (many believe that the gastric pH is more important than the gastric volume).

Question 2

You note gastric contents in the oropharynx following extubation.

What are you going to do?

Answer 2

In this situation, I would immediately –

1. begin placing the patient in the head-down position (to facilitate drainage of gastric contents out of the lungs), while at the same time,
2. directing someone to apply cricoid pressure and
3. suctioning out the oropharynx.

I would then:

1. re-intubate the patient to prevent additional aspiration;
2. apply suctioning through the ETT in an attempt to remove aspirated material;
3. provide 100% oxygen;
4. support ventilation as necessary (suctioning of the oropharynx and through the ETT should be performed prior to positive pressure ventilation in order to prevent the distal dissemination of aspirated material);
5. insert an orogastric tube to empty the stomach and determine the pH of gastric content;
6. collect a sample of tracheal aspirate for culture and sensitivity testing;
7. order a baseline chest x-ray and arterial blood gas;
8. treat any bronchospasm with B2-agonists; and
9. monitor the patient for 24-48 hours for the development of aspiration pneumonitis.

I would NOT administer steroids or prophylactic antibiotics, given the lack of evidence that these measures are effective.

Bronchoscopy may be helpful in the removal of particulate aspirate.

Question 3

Are prophylactic antibiotics or steroid therapy indicated?

Answer 3

Prophylactic antibiotics have NOT been shown to improve mortality or reduce secondary infection.

Therefore, since prophylactic administration can lead to drug-resistance and superinfection, I would only consider antibiotic therapy if:

1. the patient demonstrated a bacterial infection based on culture and sensitivity testing;
2. there was a high likelihood of gram-negative or anaerobic organisms, such as occurs in the setting of bowel obstruction; or
3. the patient’s clinical course failed to improve, or worsened, after 2-3 days.

Since corticosteroids have failed to demonstrate a beneficial effect on pulmonary function, lung injury, alveolar-capillary permeability, or patient outcome, they are NOT indicated for the treatent of aspiration.

Question 4

What steps could you have taken to reduce the risk for aspiration during this emergent surgery?

Answer 4

Preoperatively, I could have administered –

• metoclopramide (???) , to stimulate gastric emptying and increase lower esophageal sphincter tone,
• an H2-receptor antagonist, to decrease acid secretion, and
• a non-particulate antacid, to raise the pH of gastric contents.

At induction, assuming a reassuring airway, I could have placed her in reverse-trendelenburg position, performed a rapid sequence induction with cricoid pressure, decompressed her stomach with a nasogastric tube following intubation, and delayed extubation until she was awake and demonstrating a return of airway reflexes.