What are the typical lung sounds and management for aspiration?

Lung Sounds in Aspiration

In aspiration, the most common lung sounds are crackles (rales), wheezing, and decreased or absent breath sounds, with cough being the predominant clinical sign; however, silent aspiration occurs frequently without any audible respiratory symptoms, particularly in high-risk populations.

Clinical Presentation of Aspiration

Audible Respiratory Signs

Cough is the hallmark clinical sign of aspiration and should prompt immediate evaluation for dysphagia and aspiration risk 1. Additional respiratory sounds and symptoms include:

• Wheeze - commonly present with aspiration events 1
• Stridor - indicates upper airway involvement 1
• Crackles/rales - result from inflammatory changes in lung parenchyma 2, 3
• Decreased or absent breath sounds - particularly on the affected side, indicating atelectasis or consolidation 4
• Wet or gurgly voice quality after swallowing - the "wet voice" is a gurgling sound on phonation that indicates pooled secretions 1
• Increased respiratory secretions with tachypnea 1

Silent Aspiration: A Critical Pitfall

Silent aspiration occurs without any clinical symptoms during feeding and is extremely common in high-risk populations 1. This represents a major diagnostic challenge:

• In preterm infants undergoing videofluoroscopic swallow studies (VFSS), approximately one-third with normal clinical feeding evaluations demonstrated silent aspiration 1
• Among 130 preterm infants studied, 77% had aspiration or laryngeal penetration on VFSS despite lack of obvious symptoms 1
• All nine premature infants with vocal cord paralysis had silent aspiration in one retrospective review 1

High-Risk Populations Requiring Evaluation

Patients with unexplained cough and any of the following conditions should be referred for oral-pharyngeal swallow evaluation, ideally to a speech-language pathologist 1:

• Reduced level of consciousness (these patients should not be fed orally until consciousness improves) 1
• Neurologic conditions (stroke, particularly bilateral strokes where 84% of aspirators had weak or absent voluntary cough) 1
• Cough related to pneumonia or bronchitis with associated aspiration risk factors 1
• Post-prematurity respiratory disease with persistent oxygen desaturation during feeding 1
• Suspected or confirmed vocal cord paralysis or other airway anomalies 1
• Failure to wean from oxygen therapy or ventilatory support as expected 1

Bedside Clinical Assessment

Water Swallow Test

Alert patients in high-risk groups should be observed drinking 3 ounces of water 1. Positive findings requiring referral for detailed swallowing evaluation include:

• Coughing during or after swallowing 1
• Wet voice quality after swallowing 1
• Throat clearing 1
• Hoarse voice or dysphonia 1

The sensitivity for detecting aspiration improves when multiple signs are present together 1.

Voluntary Cough Assessment Limitations

The subjective assessment of voluntary cough as the sole predictor of aspiration has uncertain value due to poor reliability 1. While weak or absent voluntary cough was found in 84% of aspirators with bilateral strokes, this assessment alone should not be relied upon 1.

Management Approach

Immediate Actions

For patients with clinical signs of aspiration during feeding:

1. Stop oral feeding immediately if cough, oxygen desaturation, or other aspiration signs occur 1
2. Maintain airway patency and provide supplemental oxygen if needed 5
3. Refer for videofluoroscopic swallow study (VFSS) - this is the gold standard for diagnosis 1

Diagnostic Evaluation

VFSS is recommended for infants, children, and adolescents with post-prematurity respiratory disease who are eating by mouth and have 1:

• Cough or persistent oxygen desaturation during feeding
• Suspected or confirmed vocal cord paralysis
• Failure to thrive
• Chronic pulmonary symptoms out of proportion to viral infections

Treatment Based on Aspiration Type

The management differs based on whether bacterial aspiration pneumonia or chemical aspiration pneumonitis is present:

Aspiration Pneumonia (bacterial):

• Occurs in elderly, debilitated patients with dysphagia 2
• Causative organisms include pneumococcus, Haemophilus influenzae, Staphylococcus aureus, and anaerobes (present in 12-76% of cases) 1, 6
• Requires broad-spectrum antibiotics covering oral flora and anaerobes 2, 6
• Management of underlying dysphagia is essential to prevent recurrence 2

Aspiration Pneumonitis (chemical):

• Follows aspiration of gastric contents in patients with decreased consciousness 2
• Treatment is essentially supportive with airway management and oxygenation 2
• Corticosteroids and immunomodulating agents may have a role 2

Prevention Strategies

Early measures to prevent aspiration are critical 6:

• Thickened feeds for patients with documented aspiration on VFSS 1
• Positioning modifications during feeding 1
• Swallowing therapy with speech-language pathologist 1
• Do not feed patients orally if they have reduced consciousness 1

Key Clinical Pitfalls

• Do not rely on the absence of cough to rule out aspiration - silent aspiration is common and dangerous 1
• Do not assume normal clinical feeding evaluation excludes aspiration - one-third of such patients had silent aspiration on VFSS 1
• Voluntary cough testing alone is unreliable for predicting aspiration risk 1
• Patients with vocal cord paralysis are at extremely high risk for silent aspiration and require VFSS 1
• Anaerobic coverage is essential when treating aspiration pneumonia, as anaerobes may be present in up to 76% of cases 1