ZSFG Pearl SMORGASBORD: Aztreonam, AP window, #cyalaterHCAP?

Pearl smorgasbord from ZSFG! Thank you to the residents and consultants for all the juicy, juicy learning! A few TOP PEARLS specifically from Pulm and ID reports recently…

  • If there is blunting of the AP window, consider WHAT IS IN THE MEDIASTINUM (mass vs LAD). More detail below…
  • If a patient has a PCN allergy but you REALLY want to cover them for Listeria, use BACTRIM
  • How does one approach AZTREONAM? With tender love and care. And also think about its activity in this way: G- coverage like Ceftriaxone (with a touch of anti-Pseudomonal activity a la Cefepime) but WITHOUT ESBL, anaerobic, or a socially acceptable amount of G+ coverage.

AP stands for “Aortopulmonary” window and is a radiological mediastinal space, see the exceptionally calming picture below. And what’s in the AP window? Glad you asked! The structures that traverse the AP window are:

  • L phrenic nerve
  • L recurrent laryngeal nerve
  • L vagus nerve
  • L bronchial arteries
  • ligamentum arteriosum
  • and my personal favorite: FAT


Why does the appearance of the AP window matter? Normally it has a concave lateral border. A newly straightened or convex lateral border is considered abnormal. Consider the following potential causes:

  • Mediastinal lymphadenopathy
  • Prominent mediastinal fat
  • Aortic or bronchial artery aneurysms
  • Malignancy (i.e. nerve sheath tumor)

AP window.jpg
On a more lung-related note, there has been an (awesome and academic) ruckus about that famous term HCAP

IDSA and ATS published guidelines THIS SUMMER on managing Hospital Acquired pneumonia and Ventilator-associated pneumonia (see link below). Interestingly, they ghosted on healthcare-associated pneumonia. Use of this term and the previous abx guidelines that went with it have led to wide-spread and somewhat longer-than-recommended use of broad-spectrum antibiotics. Additionally, further lit review has shown that the usual HCAP risk factors were neither sensitive nor specific to identify patients at risk for worse outcomes. In fact, poor clinical outcomes with HCAP were felt to be related more strongly with age and comorbidities rather than multi-drug resistant organisms per se.

In light of not addressing HCAP in this year’s abx guidelines, many ID experts think that the nuances will be teased out in IDSA recommendations on how to treat severe CAP or CAP in patients with significant comorbidities.  These recs will be discussed in the IDSA “Community Acquired PNA in adults guidelines” that are projected to be published in the summer of 2017.

Evernote link: https://www.evernote.com/shard/s354/sh/93597385-1a79-4ee2-931d-fb77ad17f0fd/b0ddbe2c95e15a0c1ad8bf95c3f9cf6e



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