Severity assessment of HAP

Empirical therapy for hospital-acquired pneumonia (HAP) is stratified according to disease severity.

When determining the empirical therapy regimen for HAP, first assess whether the patient has

  • high-severity HAP
  • low- to moderate-severity HAP.

The criteria for diagnosing high-severity HAP are not well defined – for the definition of high-severity HAP used in these guidelines, see Criteria for diagnosing high-severity HAP. Severity scoring systems have been developed for community-acquired pneumonia (CAP) but not validated for HAP. For patients with high-severity HAP, empirical antibiotic therapy with activity against a broad range of pathogens, including Pseudomonas aeruginosa, is recommended. For management, see High-severity HAP.

In these guidelines, patients without features of high-severity HAP are considered to have low- to moderate-severity HAP. Monitor patients with low- to moderate-severity HAP closely for signs of deterioration:

For management of patients with low- to moderate-severity HAP, see Low- to moderate-severity HAP. If a patient with low- to moderate-severity HAP continues to deteriorate, consider escalating to broader-spectrum antibiotic therapy by treating as for high-severity HAP.

Figure 1. Criteria for diagnosing high-severity HAP

The criteria for diagnosing high-severity HAP are not well defined. In these guidelines, high-severity HAP includes patients with any of the following features:

  • signs of sepsis or septic shock – in adults, this includes hypotension (systolic blood pressure lower than 90 mmHg) or blood lactate concentration more than 2 mmol/L [NB1]
  • respiratory failure, particularly if requiring intensive care support or mechanical ventilation
  • rapid progression of infiltrates on chest X-ray.
Note:

NB1: Blood lactate can be measured using arterial or venous blood gas analysis. Venous blood gas analysis is acceptable for rapid lactate assessment.

Figure 2. Red flags that indicate potential deterioration in adults with low- to moderate-severity hospital-acquired pneumonia

Adults who do not meet the criteria for high-severity HAP but have any of the following red flags that indicate potential deterioration should be closely observed and reassessed by an experienced clinician to identify deterioration early (particularly adults with multiple red flags):

  • tachypnoea (respiratory rate higher than 22 breaths per minute)
  • tachycardia (heart rate higher than 100 beats per minute)
  • acute-onset confusion
  • oxygen saturation lower than 92% on room air (or lower than baseline in adults with comorbid lung disease)
  • multilobar involvement on chest X-ray.