UMEM Educational Pearls

Category: Critical Care

Title: The HACOR score to predict intubation need in acute respiratory failure.

Keywords: HACOR, NIV, noninvasive ventilation, acute respiratory failure (PubMed Search)

Posted: 2/2/2021 by Kami Windsor, MD (Emailed: 2/23/2021) (Updated: 2/23/2021)
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BackgroundIn respiratory failure due to COPD and cardiogenic pulmonary edema, noninvasive positive pressure ventilation decreases need for intubation and improves mortality,1 while its utility in other scenarios such as ARDS and pneumonia has yet to be proven.1,2 We know that patients on NIV with delays to needed intubation have a higher mortality,1,3 but intubation and mechanical ventilation come with risks that it is preferable to avoid if possible.

 

So how and when can we determine that NIV is not working?

 

The HACOR (Heart rate, Acidosis, Consciousness, Oxygenation, Respiratory rate) score at 1 hour after NIV initiation has been demonstrated to be highly predictive of NIV failure requiring intubation.4,5 

 

Initial development/validation: Score > 5 after 1 hour of NIV corresponds to >80% risk of NIV failure4

  • Earlier intubation (before 12 hours) in these patients = better survival

External validation: Score > 8 after 1 hour of NIV most predictive of eventual NIV failure 5

  • Average score @ 1-hour of patients with NIV success = 3.8

  • Score remained predictive at 6, 12, 24, 48 hours as well & mortality worsened as delay to intubation time increased 

  • Baseline, pre-NIV score not predictive

  • Better predictive agreement in pneumonia and ARDS

Bottom Line:

  • Patients on NIV require close reassessment to prevent worsened survival due to intubation delay should invasive mechanical ventilation be indicated.

  • A HACOR score >8 after 1 hour of NIV should prompt intubation in most instances, with strong consideration given to a score >5.

 

*Note: ABGs were obtained for PaO2 assessment in the above studies -- the use of SpO2 was not evaluated -- but we are often not obtaining ABGs in our ED patients with acute respiratory failure. The following chart provides an estimated SpO2 to PaO2 conversion.

 

 

WHO 2001

Caveats: 

  1. Pulse oximetry may be inaccurate in darker skin tones (overestimated by ~2%)6 and in certain disease processes (e.g. CO poisoning, profound shock states, etc.)
  2. The oxyhemoglobin dissociation curve shifts right with increasing pCO2/decreasing pH (lower saturation for a given PaO2).

References

  1. Rochwerg B, Brochard L , Elliott MW, et al. Official ERS/ATS clinical practice guidelines: noninvasive ventilation for acute respiratory failure. Eur Respir J. 2017;50(2):1602426.
  2. Antonelli M, Conti G, Moro ML, et al. Predictors of failure of noninvasive positive ventilation in patients with acute hypoxemic respiratory failure: a multi-center study. Intensive Care Med. 2001;27(11): 1718-28.
  3. Demoule A, Girou E, Richard JC, et al. Benefits and risks of success or failure of noninvasive ventilation. Intensive Care Med. 2006;32(11):1756-65.
  4. Duan J, Han X, Bai L, et al. Assessment of heart rate, acidosis, consciousness, oxygenation, and respiratory rate to predict noninvasive ventilation failure in hypoxemic patients. Intensive Care Med. 2017;43(2):192-9.
  5. Carrillo A, Lopez A, Carrillo L, et al. Validity of a clinical scale in predicting the failure of non-invasive ventilation in hypoxemic patients. J Crit Care. 2020;60:152-8.
  6. Sjoding M, Dickson R, Iwashyna T, Gay S, Valley T. Racial Bias in Pulse Oximetry Measurement. N Engl J Med. 2020;383(25):2477-8.