Making sense of the guidelines: pneumonia

I am reposting my 11/03/08 pneumonia guideline summary because the categories need clarification. Updated comments are italicized.

The pneumonia guidelines are complicated. They consist of two sets of guidelines (community acquired pneumonia, CAP, and health care associated pneumonia, HCAP) which are distinct but have just enough overlap to be confusing. Both guidelines stratify patients into high and low resistance risk groups. The respective groups are similar in the two guidelines with distinctions that seem nit picking and at times don’t make sense. (Why, for example, is ceftazidime listed as an antipseudomonal drug in the HCAP guideline but not the CAP guideline?). Add to this the criteria for site of care (home vs ward vs ICU) and de-escalation (PO switch, discharge and stopping therapy). Who can remember it all? You can look it up each time---the guidelines are open access full text---but opening up and browsing those large pdf files is cumbersome.

Is it worth the trouble? Although guidelines are not a substitute for clinical judgment, you may ignore them at your patients’ peril. In the case of pneumonia it has been shown repeatedly (here, here, here, here, here, and here) that guideline adherence is associated with better outcomes.

Here is my attempt to remedy pneumonia guideline chaos by condensing the essentials in one post. The figures below summarize the information I find my self looking up most often. (The complete guidelines should be read in their entirety, once or twice. They contain a world of information on etiology, pathogenesis and diagnosis, not covered here).

Hospital acquired pneumonia (HAP), ventilator associated pneumonia (VAP) and health care associated pneumonia (HCAP) are listed in the guidelines as separate categorizations. Among these three categories, however, the antibiotic recommendations are based on microbiologic risk and are the same for a given level of risk. Therefore, for purposes of this guideline summary I have lumped the three categories together as HCAP.

A practical definition of HCAP which encompasses all three categories is pneumonia with any one of the following characteristics: onset 48 hours or more after admission; two or more days of acute care hospitalization in the past 90 days; nursing home residency; IV antibiotic therapy, chemotherapy or wound care within the past 30 days; hemodialysis. Other pneumonias would be considered community acquired pneumonia (CAP).

After adjudicating a patient as CAP or HCAP go to the appropriate section below to assign microbiologic risk. Note that conditions defining a patient as “HCAP” and “HCAP, high microbiologic risk” overlap greatly but are not interchangeable. Rigid application of some distinctions becomes nit picking. Clinical judgment and common sense are required.

The fourth line under the category HCAP, high microbiologic risk should read “two or more days of hospitalization in the last 90 days.”






Note: The above table classifies CAP and HCAP according to the risk of resistant organisms. CAP is also independently classified as to eligibility for ICU placement. Aside from the obvious indications of shock and mechanical ventilation, guideline recommendations for ICU placement include patients with any 3 of: RR 30 or above; PO2/FiO2 250 or below; multilobar infiltrates; acute alteration in mental status; BUN 20 or above; WBC below 4000; platelet count below 100,000; hypothermia (core below 36C); hypotension requiring fluid challenge.

Admission decisions can be based on the CURB-65 criteria or the pneumonia severity index.

Miscellaneous: No time rule for antibiotic admin; guidelines say give in ER. Legionella and pneumococcal urine antigen determinations are recommended for many, but not all, categories of patients. For CAP, blood cultures are considered optional in some of the lowest risk patients.

New evidence post guideline publication: Steroids for severe CAP? Maybe; stay tuned. Statins? Promising. CA-MRSA is a bad actor, and is emerging. Think of it.