Levels of monitoring of patients receiving noninvasive ventilation (NIV)
| General ward | HDU | ICU | |
| Degree of severity of respiratory failure | Mild | Moderate | Severe |
| pH [10, 14, 28] | 7.35–7.30 | 7.30–7.20 | <7.20 |
| Respiratory rate breaths·min-1 | |||
| Restrictive disorders | <30 | 30–35 | >35 |
| Obstructive disorders | <25 | 25–35 | >35 |
| Level of consciousness | |||
| GCS | 15 | 10–14 | <10 |
| Kelly's scale [121] | 1 | 2–4 | 5–6 |
| Failure of other organs | No | Debatable | Yes |
| Oxygenation | Corrected with low-flow oxygen (nasal prongs) | Corrected with high-flow oxygen (Venturi mask or nonrebreathing mask) | Not corrected with high-flow oxygen |
| PaO2/FIO2 ratio [122–124] | >150 | <150 | <100 |
| Monitoring | |||
| Medical staff surveillance | |||
| Continuous nurse monitoring | Not necessary | Indicated | Obligatory |
| Pulmonologist on duty | Preferable | Obligatory | Preferable |
| Intensivist on duty | Not necessary | Preferable | Obligatory |
| Clinical assessment | |||
| Blood pressure | Occasional | Occasional | Continuous |
| Heart rate# | Occasional | Continuous | Continuous |
| Respiratory rate | Occasional | Continuous | Continuous |
| Level of consciousness | Not necessary | Frequent | Frequent |
| Gas exchange | |||
| SpO2 | Every 2–4 h | Continuous | Continuous |
| Arterial blood gas analysis¶ | Every 8 h | Every 2–4 h | Frequent by arterial line |
| PtcCO2 | Not necessary | Indicated | Indicated |
| Ventilator parameters | |||
| Leak, VTE, I:E, V′E | Every 2–4 h | Every 1 h | Continuous |
| Patient–ventilator asynchrony | Occasional | Frequent | Frequent |
| Flow traces | Not necessary | Indicated | Obligatory |
| Compliance and resistance | Not necessary | Indicated | Obligatory |
Note that most of the values are not scientifically confirmed and cannot be understood as strict cut-off points, but rather as helpful tips to manage a patient receiving NIV. HDU: high-dependency unit; ICU: intensive care unit; GCS: Glasgow coma scale; PaO2: arterial oxygen tension; FIO2: inspiratory oxygen fraction; SpO2: arterial oxygen saturation measured by pulse oximetry; PtcCO2: transcutaneous carbon dioxide tension; VTE: expiratory tidal volume; I:E: inspiration to expiration ratio; V′E: minute ventilation. #: by ECG monitoring; ¶: first assessment should be made within first hour of NIV, then depending on patient's clinical state and always in cases of deterioration; frequency should be maintained until improvement and stabilisation of respiratory insufficiency.