This bread-and-butter ICU topic has appeared in the exams many times. Relevant questions have included the following:
The most important primary sources for the information summarised here would have to include the following:
They are all pretty much the same, making a series of similar recommendations. ASID is the local body in charge of this, and they have yet to issue a position statement on Australian pneumonia. We must assume that one infected lung is much like another, and rely on foreign Thoracic Societies.
In Question 18 from the first paper of 2012, the college asked for "features which suggest a poor prognosis".
As their model answer, they offered the candidates a cut-and-pasted table from the 2007 ISDA Guidelines. I reproduce it below:
There are several alternative scoring systems:
Which of these tools is best? According to a 2010 meta-analysis by Chalmers et al, they are all much the same. Niederman (2009), in a narrative review, suggests that these tools mainly differ according to the intended application. The old PSI and the NICE guideline-recommended CURB65 score are both very good at identifying good for low-morality patients and there therefore better in the ED and the GP clinic. The IDSA/ATS guidelines and the SMART‐COP tool are probably better at identifying the patients at need of ICU care. For the purposes of completeness, the SMART-COP tool is included below:
For completeness, here's the CURB65 score, which is calculated by giving 1 point for each of the following prognostic features:
Patients are stratified for risk of death as follows:
Why is risk stratification important? Prragmatically, it is because Question 2 from the first paper of 2018 asked about the factors which influence the decision to admit to ICU, vs. send home or to the ward. It makes greatest sense that ICU admission should be considered for the high risk patients, i.e. those at greatest risk of mortality. One might also add that ICU admission would be inappropriate for patients in whom mortality is expected to be inevitable regardless of treatment, and that should probably also factor into the decision.
Question 26 from the first paper of 2006 and Question 2a from the second paper of 2003 request that the candidate take a rich full history from the patient and their family, focusing on those things which might have some importance in community-acquired pneumonia. The two questions are essentially identical. The "model" college answer has been reworked into a list of important historical features, which is reproduced below:
Patient's medical history of prognostic importance
Recent history of aetiological importance
Presenting history
Features which help narrow the organism
The cavernous innards of the BTS guidelines statement contain the very useful "Box 1" (page iii16) which describes "clinical features reported to be more common with specific pathogens". The content of this box is reproduced below to speed revision:
Clinical features of specific pathogens:
In Question 18 from the first paper of 2012, the college again quotes directly from the ISDA guidelines.
The most common microbes are:
In the model answer to Question 2b from the second paper of 2003, the college lists a series of investigations which they would expect their candidate to mention. Of the following list of tests, the normal font identifies the college canon, and the italicised ones were added by the deranged author.
This list of diagnostic tests was assembled from the 2007 IDSA guidelines statement. There are arguments against the routine use of blood and sputum cultures, given that their yield is poor and they do not tend to influence management. Similarly, urinary antigen tests do not tend to change your antibiotic decisions for the majority of patients However, the IDSA recognises that some patients are sick enough to merit an extended spectrum of tests. Table 5 from their publication lists the indications for such extended testing. ICU admission is at the top of that list. Ergo, any patient asked about in the CICM exam is deserving of extra attention by default.
The evidence and utility of these investigations can be examined in some greater detail:
2007 ISDA guidelines recommend a broad-spectrum third generation cephalosprin (eg. ceftriaxone 1g bd) and a macrolide (eg. azithromycin 500mg daily). These should be given IV, for a minimum of 5 days (but more likely for 7). Question 2c from the second paper of 2003 obviously predates these guidelines, and recommends old-school erythromycin as the macrolide of choice. A sole agent fluoroquinolone (moxifloxacin) may be substituted.
The most recent NICE guidelines make the following recommendations for the British pneumonia patient with moderate or severe disease:
The NICE authors then go on to admit that their recommendations are based more on their experience than on any sort of published evidence, given the quality of what is available.
What is non-response, or 'treatment failure"? I may borrow liberally from the recent 2015 Torres paper, where a series of descriptive criteria were used to determine whether the steroids were working. These criteria were worsening radiological appearance, failure to wean from ventilation (or requiring intubation, or re-intubation), worsening respiratory variables (eg. PaO2/FiO2 ratio), or development of shock. More broady, non-response may be simply the failure of the patient to progress quite as quickly as you would prefer. Question 7 from the second paper of 2012 asks the candidates to "outline the factors that may affect the expected rate of resolution" for a patient with community-acquired pneumonia who has failed to improve after 5 days of mechanical ventilation.
How long do you wait for it to resolve? Even eminent authors admit that the time-based definitions are arbitrary. And when do you start the timer; is it from the first productive cough? From intubation? What if the patient has been having courses of ridiculously inappropriate antibiotics, and has not yet had any treatment per se (so how can he be "treatment refractory"?).
A sufficiently severe pneumonia may be slow to resolve for a variety of reasons which are not at all associated with inappropriate management. A recent article (Meiling et al, 2014) has found that while poor antibiotic choice plays a role, multilobar infiltration and a high CURB-65 score were important independent risk factors for a treatment-refractory slow-to-resolve pneumonia. Not surprisingly, it has a substantially increased mortality associated with it (according to LITFL, five-fold). In total there are several factors which are known as predictors of a poor response to antibiotics; these are listed in the excellent 2007 article by Menendez and Torres.
The table offered below is compiled from college answers to the previous SAQs on this topic, as well as from the abovequoted papers.
Wrong disease
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Wrong antimicrobial agents
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Predictors of poor response to antibiotics:
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A brilliant article on this topic is offered from Clinics in Chest Medicine (Kuru and Lynch, 1999), but unfortunately it is behind a paywall. The next best source is probably the UpToDate page on nonresolving pneumonia. Again, access to the latter requires the exchange of money. This LITFL article, however, is free.
The 2007 ISDE guidelines (used to answer Question 18 from the first paper of 2012) are:
The newer 2014 NICE guidelines (for ICU-level severe pneumonia) recommend 7-10 days of antibiotics; however nothing else is said about this subject. The procalcitonin RCT mentioned in the SAQ is a famous study where antibiotic therapy was deescalated according to a procalcitonin level (anything less than 0.25mic/L was grounds for deescalation).
Though the 2009 BTS guidelines did not favour the use of steroids, they did admit that their evidence for this opinion was of particularly poor quality, and that the whole thing resembled gut instinct rather than a well-reasoned recommendation. Fortunately, a flurry of interest in using steroids for pneumonia was aroused after two new trials were published in 2015. Torres et al investigated high-acuity ICU patients, whereas Blum et al looked at the broader population of hospital in-patients. In the severely ill group, steroids decreased the chances of "treatment failure" as defined by deteriorating circulatory or respiratory function, but without much of an impact on mortality. The publication of these trials stimulated the college to ask about this issue in Question 5 from the first paper of 2016. The CAPE-COD trial, published in 2023, has likely awakened the eldritch entities responsible for that SAQ, and more such questions could be inbound.
"Time to change practice", writes Djillali Annane, the great champion of using steroids for everything. "Not for everyone", writes Richard Wunderink, citing some valid concerns regarding the methodology of this recent 2015 Torres study. For instance:
The college answer to Question 5 from the first paper of 2016 had mentioned that Up-to-Date had included this in one of their practice-changing updates (Nov. 2015). UpToDate now recommend steroids for CAP with a Grade 1B recommendation. However, "not yet accepted therapy" and "treatment effect small" are the summary statements made by the college in their model answer.
Folk wisdom in the ICU has historically been to view NIV as a prelude to intubation, as far as pneumonia is concerned. The reasoning behind this opinion is the impediment to normal cough which results from the use of NIV, particularly in the frail elderly. If you cannot clear your purulent sputum, you cannot achieve source control, and therefore all the effort-of-breathing improvements achieved with NIV end up being for nought. There have never been questions regarding this specific issue in the CICM Part II, and in any case the answer would belong somewhere in the NIV chapter of the mechanical ventilation section. In brief, all evidence suggests that the only pneumonia patients who benefit from NIV are those who also happen to have a coexisting NIV-treatable disease (eg. acute pulmonary oedema or COPD).
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