This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.
Noninvasive ventilation (NIV) through a face mask can avoid intubation in many patients with acute respiratory failure, but when it fails, delaying intubation worsens outcomes. The HACOR score, published by Jun Duan and colleagues in 2017 from 449 patients with hypoxemic respiratory failure, helps spot early failure. Its name lists its five items: Heart rate, Acidosis, Consciousness, Oxygenation and Respiratory rate.
The points
| Variable | Values and points |
|---|---|
| Heart rate | 120/min or less: 0; 121 or more: 1 |
| pH | 7.35 or more: 0; 7.30 to 7.34: 2; 7.25 to 7.29: 3; under 7.25: 4 |
| Glasgow coma scale | 15: 0; 13 to 14: 2; 11 to 12: 5; 10 or less: 10 |
| PaO2/FiO2 (mmHg) | 201 or more: 0; 176 to 200: 2; 151 to 175: 3; 126 to 150: 4; 101 to 125: 5; 100 or less: 6 |
| Respiratory rate | 30/min or less: 0; 31 to 35: 1; 36 to 40: 2; 41 to 45: 3; 46 or more: 4 |
The score ranges from 0 to 25. Consciousness weighs most: a Glasgow score of 10 or less alone exceeds the threshold.
When to calculate it
HACOR is measured before NIV and again after 1 hour of NIV, and can be repeated later. The 1-hour value predicts best.
Example
After an hour of NIV, a patient has a heart rate of 115 (0), a pH of 7.32 (2), a Glasgow score of 15 (0), a PaO2/FiO2 of 160 (3) and a respiratory rate of 32 (1). The score is 6, above the threshold of 5, so the risk of NIV failure is high.
Interpretation
- 5 or less after 1 hour: NIV can be continued with close monitoring.
- Above 5 after 1 hour: in the original studies, most of these patients eventually needed intubation, and those intubated within the first 12 hours had lower hospital mortality than those intubated later.
A later update by the same team added baseline factors such as the diagnosis, immunosuppression and the SOFA score to improve prediction.
Related tools
The ROX index (SpO2/FiO2 ÷ respiratory rate) plays a similar role for high-flow nasal oxygen. Neither score replaces bedside judgment: rising work of breathing, exhaustion, agitation, vomiting or hemodynamic instability are reasons to intubate whatever the score.