Table 2.
Clinical and functional assessment of severe asthma exacerbations
| Variable | Severe exacerbation | Imminent respiratory arrest |
| Symptoms | ||
| Dyspnea | At rest | |
| Speech | Single words, not sentences of phrases | |
| Alertness | Agitated | Drowsy or confused |
| Signs | ||
| Respiratory rate | >30 breaths/min | |
| Heart rate | >120 beats/min | Bradycardia |
| Pulsus paradoxus | >25 mmHg | Absence (muscle fatigue) |
| Use of accessory muscles | Evident | Abdominal paradox |
| Wheeze | Present – loud | 'Silent chest' |
| Functional assessment | ||
| PEF | <50% of predicted | |
| PaO2 | <60 mmHg | |
| PaCO2 | >42 mmHg | |
| SaO2 | <90% |
PaCO2, arterial carbon dioxide; PaO2, arterial oxygen; PEF, peak expiratory flow; SaO2, oxygen saturation. Adapted from the National Heart, Lung and Blood Institute report [1].