Aspiration pneumonia refers to the pulmonary consequences resulting from the abnormal entry of fluid, particulate exogenous substances or endogenous secretions into the lower airways. There are usually two requirements to produce aspiration pneumonia:

  • Compromise in the usual defenses that protect the lower airways including glottic closure, cough reflex, and other clearing mechanisms
  • An inoculum deleterious to the lower airways which causes a direct toxic effect (such as gastric acid), stimulation of an inflammatory process from bacterial infection or obstruction due to un-cleared fluid or particulate matter

The aspirated fluid can be oropharyngeal secretions, particulate matter, or can also be gastric content.

The term aspiration pneumonitis refers to inhalational acute lung injury that occurs after aspiration of sterile gastric contents. In an observational study, it is found that the risk of patients hospitalised for community-acquired pneumonia in developing aspiration pneumonia is found to be about 13.8%. The mortality rate from aspiration pneumonia is largely dependent on the volume and content of aspirate and can range to 70%.1,2,3,4

Pathophysiology

Aspiration pneumonia is very common in long term care and community facilities such as nursing and residential homes where patients may have impaired airway defenses and immune mechanism. These patients may have additional risk factors such as nasogastric (NG) and PEG tubes.

The early stage of aspiration pneumonia is chemical pneumonitis as the gastric content is relatively sterile due to acidic PH of the stomach contents. However, factors that change the stomach PH such as PPIs and H. Pylori gastritis, this additional defense may not be present. Regardless of the above factors, secondary bacterial infection is very common.

Depending on where aspiration happens the organisms may include anaerobes or nosocomial acquired organism such as gram-negative bacteria and Staphylococci.

Risk factors

The following risk factors should be considered:5

  • Poor oral hygiene
  • Reduced conscious levels,
  • Dysphagia,
  • GORD
  • Alcohol
  • Post seizure
  • CVA
  • Tube feeding
  • Recumbent position.

Clinical features

Thorough assessment and clinical examination are always helpful in eliciting the diagnosis of aspiration pneumonia in older patients, although physical limitations of mobility can be challenging.

The following should raise the possibility of aspiration pneumonia

  • Abrupt onset of symptoms with prominent dyspnea
  • Fever
  • Hypoxemia
  • Tachycardia
  • Tachypnoea
  • Cyanosis
  • Rales and coarse crackles
  • Decreased breath sounds
  • Pleural Friction rub.

Imaging

Chest X-ray changes can take up to two hours to appear. On the chest x-ray, the right lower lobe is most frequently involved. Patients who have aspirated while upright may have bilateral lower lobe involvement. Patients lying in the left lateral decubitus position tend to have left-sided infiltrates. The involvement of the right upper lobe is more common in patients who aspirate in the prone position and those with alcohol use disorder.

Bronchoscopy is indicated when particles of food have been aspirated. The technique also allows the retrieval of organisms for culture.

Prevention of aspiration pneumonia

Aspiration pneumonia results in increased morbidity and mortality. The early identification of patients with a high risk of aspiration allows targeted preventive measures to be implemented to decrease the incidence and early recognition of aspiration.

Oral feeding

Prevention of aspiration pneumonia in patients on oral feeding:

  • Assess all patients admitted for risk for aspiration
  • To do Bedside Swallow Screening
  • Early referral to speech specialist to assess swallowing and to suggest the suitable texture of food (use of thickened liquids or reduction of bite size or puree solids)
  • Referral to dietician for appropriate diet type
  • Education and/or supervision of patient with respect to safe swallowing
  • Proper positioning of Patients in 60-90 degree sitting position while on oral feeding and for one-hour post feeding
  • Aiding and close observation for patients with swallowing difficulty. (Feeding assistance is to be provided only by a qualified staff or well-trained care giver)
  • Avoid distraction while providing food and avoid feeding when patient is sleepy, acutely confused or agitated
  • Provide good oral hygiene with regular referral to dentist (annual referral)
  • Apply safe swallowing methods (Upright posture, chin tucked, slow swallowing head turn to functioning side in hemiplegic patients) and use maneuvers to achieve improved swallowing (e.g., Supra glottic swallow)
  • Minimizing the use of sedatives, narcotics and other drugs that decrease the level of consciousness
  • Avoidance of drugs that impair gastric emptying or provoke reflux oesophagitis
  • Remind frequently to chew, eat slowly and swallow
  • Serve appropriate foods (e.g., foods in bite-size pieces, soft foods, and thickened liquids)
  • Avoid foods that are more easily lodged in throat (e.g., nuts, popcorn, raw carrots)
  • Check for proper fitting of dentures.
  • Check for pocketing of food in the mouth
  • Always keep suction equipment ready to go beside the bed of the patient when there is a risk for aspiration pneumonia.

Tubal feeding

Prevention of aspiration pneumonia in patients on tubal feeding:

  • Position of the nasogastric tube should be verified by aspiration of gastric contents and the use of pH graded indicator paper. A gastric pH of 1 – 5.5 is recommended. Radiography (Chest X-ray) must be used as a second line test to confirm initial placement when no aspirate could be obtained, or pH indicator paper has failed to confirm the location of the nasogastric tube
  • Proper positioning of patients’ head of bed in 30 degree while not on feeding, 45 degree while on feeding up to 1-hour post feeding
  • Regular check of residual gastric volume prior to tubal feeding. (Residual gastric volume should not exceed 150 ml. If it exceeds 150 ml, the feed should be held for 1 hour and reassess)
  • Provide good oral hygiene with regular referral to dentist (annual referral)
  • Regular suction of oral secretions in patients having increased oral secretions and saliva with impaired level of consciousness
  • Avoidance of drugs that impair gastric emptying or provoke vomiting gastritis and reflux oesophagitis
  • Use of anti-emetics and drugs that improve gastric emptying (Metoclopromide)
  • Minimising use of drugs that decrease level of consciousness.

Treatment of aspiration pneumonia

The treatment varies between aspiration pneumonia and aspiration pneumonitis. The patient's position should be adjusted, followed by the suction of oropharyngeal contents with the placement of the nasogastric tube. In patients who are not intubated, humidified oxygen is administered, and the head end of the bed should be raised by 45 degrees.

Close monitoring of the patient's oxygen saturation is important and immediate intubation with mechanical ventilation should be provided if hypoxia is noted. Flexible bronchoscopy is usually indicated for large volume aspiration to clear the secretion and also for obtaining the sample of Broncho alveolar lavage for quantitative bacteriological studies.

In general practice, antibiotics are initiated immediately even though they are not required in aspiration pneumonitis to prevent the progression of the disease. The choice of antibiotics for community-acquired aspiration pneumonia are ampicillin-sulbactam or a combination of metronidazole and amoxicillin/Co-amoxiclav. In patients with penicillin allergy, clindamycin is preferred. However, in hospital-acquired aspiration pneumonia, antibiotics are needed that cover resistant gram-negative bacteria and S.aureus, so the use of a combination of vancomycin and piperacillin-tazobactam is most widely used. Once the culture results are obtained, the antibiotic regimen should be narrowed to be organism-specific.6,7,8,9,10

Like other therapeutic modalities, medications like antibiotics can have their own side effects e.g. Pseudomembranous colitis, and judicial administration of drugs with minimum possible duration of therapy should be considered. Liaison with the microbiologists is paramount and minimizes the potential side effects. Oxygenation is often needed, and some patients may even require mechanical ventilation.

Prognosis

The prognosis is dependent on patient age and other comorbidities. However, despite optimal treatment, death rates of 11-30% have been reported. Even those who survive have a prolonged recovery, and repeated admissions are common.

Further care

Urgent and timely referral to secondary care is paramount for appropriate and optimal care of the patient. Several indices and scoring systems are available to assess the severity of pneumonia, which may be of limited help in geriatric population because of some physiological alterations. Tachypnea, cough, fever and altered consciousness are features that must alert the family care physician to refer the patient to secondary care, as the morbidity and mortality associated with the aspiration pneumonia is high.

Inpatient care must be monitored carefully with radiographs, bloods, ABGs and NEWS score. High scoring should alert escalation, and age must not be considered a barrier. Besides treating pneumonia, it is important to educate the staff looking after the patient on further prevention of aspiration. This means having the head of the bed elevated, close monitoring of oxygen status, and regularly suctioning the oral cavity in patients with swallowing difficulties.  A dietary consult should be made to determine the optimal method of providing nutrition. Swallowing assessment must be carried out and if found impaired, options like PEG tube insertion must be discussed with the patient and the Gastroenterology team in a multidisciplinary meeting

A thorough and clear discussion with the families and next of kin should be done in a timely fashion, and if deemed appropriate, DNAR discussed and signed. Patient counselling is important, and the risks associated with it must be explained in a clear and elaborate manner.

In cases where patients continue to deteriorate despite the treatment or further escalation to level 2 care is not considered appropriate, liaison with the Palliative care team must be considered, and destination for palliative care (like NH etc.) should be discussed with the family/care takers.

 


Dr Raza Ahmed, Locum Consultant Respiratory Medicine, University Hospitals of Derby and Burton NHS Foundation Trust

Dr Irfan Muneeb Qazi, Consultant Geriatrician, Rumeilah Hospital, Doha Qatar

Dr Helen Zakhour, Medical Student, University Hospitals of Derby and Burton NHS Foundation Trust

Conflict of interest: none declared

 


 

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