You are asked to review a 54-year-old female in the Emergency Department who has community acquired pneumonia. The chest X-ray shows multi-lobar consolidation.
Outline the factors that will influence your decision regarding admission to the Intensive Care Unit (ICU) for this patient.

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College answer

Intensive Care admission will be required for this patient if they need: 

  • interventions that cannot be provided elsewhere in the hospital (e.g. invasive mechanical ventilation, vasopressor support, etc), or 
  • require a high level of monitoring to allow early detection of deterioration and early intervention. 

The factors that will influence the decision to admit this patient include

  1. Patient factors 
  2. ICU factors
  3. Hospital facorts

1. The patient factors include: 

History 

Presence of one or more of these features may alter the balance of risk and therefore the inclination to admit to ICU

  • Background:
    • Comorbidities, baseline function o Previous or known respiratory disease
    • Malignancy o Smoking  o Immune competence
  • History of current illness o Rapid progression of symptoms  o Contact and travel history
    • Response to therapy thus far

Examination

  • Overall clinical impression at the time of review
  • Signs of respiratory distress
  • Signs of other acute or chronic organ failure

Investigations

  • Routine venous blood o hyponatraemia, elevated creatinine, abnormal LFTs, DIC, anaemia…
  • ABG 

o A-a gradient, acidaemia, CO2

  • ECG
  • CXR

Severe Community acquired Pneumonia scoring systems

  • There are several of these:
    • PSI o CURB-65
    • ATS criteria
    • SMART-COP
  • None have sufficient sensitivity or specificity to be used alone

2.         ICU Factors include

  • Local admission policy and culture
  • Bed and nursing staff availability
  • Specific bedspace availability (if isolation required)

3.         Hospital Factors

  • Bed availability and capability (e.g. is there a respiratory high dependency unit?)
  • Monitoring facilities on ward
  • Oxygen delivery capability of ward (?HFNP)

Medical, nursing staff and ancillary support staff (e.g., physiotherapy) capability of the ward

Summary

The decision to admit the patient to the ICU will depend on the intersection between how sick the patient currently is, the best prediction of the likely clinical course over the next 24 hours, the capacity of the ICU to admit further patients and the capacity of the ward in that particular hospital to care for a moderately unwell patient with the potential to deteriorate and require further invasive interventions. 

Examiners Comments:

Overall answered well, with good answers considering patients background morbidities as well as local hospital and ICU factors.

Discussion

"local admission policy and culture" is an excellent euphemistic way of saying either "we are an obstructive and unhelpful ICU" or "we admit anything". 

This question can be answered in a couple of different ways, depending on how you interpret it. One way would be to discuss the risk stratification (where patients at the greatest risk of death would be admitted to ICU), which would then lead to the discussion of whichever scoring systems you feel most comfortable with. The other way would be to start the discussion in terms of hospital resources and capacity. The college clearly wanted a large amount of the latter. Their model answer leaves little to improve upon. To be different in a totally arbitrary way which does not necessarily produce a better answer, one might reclassify the factors influencing ICU admission decisions into two broad groups: illness severity and resource requirement

Illness severity

  • Pneumonia severity:
    • Mortality as predicted by scoring systems (see below)
    • Level of respiratory support required (i.e. does the patient require HFNP, NIV or intubation?)
  • Acute comorbidity
    • Level of haemodynamic support required (i.e. does the patient need vasopressors, and if yes, then is there anywhere other than the ICU where they can be administered? The answer is usually no). 
    • Coesisting organ system dysfunction (i.e. acute renal failure, liver dysfunction, DIC, etc)
  • Chronic comorbidity
    • Chronic cardiac disease (likely to decompensate)
    • Chronic respiratory disease (lower reserve)
    • Immunosuppression
    • Fraily (i.e. is the patient unlikely to survive irrespective of whether or not they come to ICU?) 

Resource requirements

  • Skills
    • Level of cover (ward vs. ICU) - availability of respiratory physician, after-hours anaesthetic cover in the event that intubation becomes necessary
    • Ward staff may not be familiar with HFNP/NIV even if this were available outside the ICU
    • ICU staff may not be sufficiently experienced with prone ventilation 
  • Manpower
    • ​​​​​​​Sufficient nursing ratio to care for this complex patient
    • Respiratory or infectious diseases physicians may not be available (eg. small regional hospital)
    • An intensivist may not be available (small regional units are often run by physicians or anaesthetists)
  • Bed space logistics
    • A single isolation room might be required
    • Telemetry or hardwired monitoring may not be available outside the ICU in smaller centres
    • ​​​​​​​
  • Equipment
    • HFNP-enabled gas supply may not be available in the ward areas
    • The ICU may not be resourced to care for a patient who requires dialysis (small regional centres) or ECMO (most centres other than large tertiary units).
    • The pharmacy may have neither prostacycline nor nitric oxide

In an idealised setting, with an infinite number of 1:1 nurses and single rooms, pneumonia severity would be the only factor which needs to be considered. The severity of pneumonia is assessed by means of various scoring systems, which attempt to predict mortality. These are worth discussing in detail. 

Pneumonia severity scoring systems:

Of the possible risk stratification tools, one may need to commit to just one for the purposes of this question. There are many:

The college, in their answer to Question 18 from the first paper of 2012, used the IDSA/ATS document (to the extent that they cut and pasted the criteria directly into their model answer with zero modification).  These are reproduced below:

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 SMARRT-COP tool is included below:

SMART-COP

In case you want to use it, the CURB 65 score is calculated by giving 1 point for each of the following prognostic features:

  • confusion (abbreviated Mental Test score 8 or less, or new disorientation in person, place or time
  • raised blood urea nitrogen (over 7 mmol/litre)
  • raised respiratory rate (30 breaths per minute or more)
  • low blood pressure (diastolic 60 mmHg or less, or systolic less than 90 mmHg)
  • age 65 years or more.

Patients are stratified for risk of death as follows:

  • 0 or 1: low risk (less than 3% mortality risk)
  • 2: intermediate risk (3‑15% mortality risk)
  • 3 to 5: high risk (more than 15% mortality risk).

Whichever guidelines you use, 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.

References