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Table 1 Trial extubation protocol

From: Effect of high-flow nasal therapy on patient-centred outcomes in patients at high risk of postoperative pulmonary complications after cardiac surgery: a study protocol for a multicentre adaptive randomised controlled trial

Mechanical ventilation and tracheal extubation after cardiac surgery

Patients’ lungs will typically be mechanically ventilated with FiO2 40–60%, PEEP 5–10 cm H2O, tidal volume (TV) 5–8 ml/kg ideal body weight and RR 10-20 breaths/min to achieve PaO2 > 8 kPa, PaCO2 4–6 KPa and peak pressure < 30 cms H2O. If failing to achieve these parameters, ventilator settings may be adjusted, and medical team consulted for advice.

The aim is to wean the patient from mandatory ventilation and switch to spontaneous breathing using pressure support (PS)/continuous positive airway pressure (CPAP) as soon as possible. Once the patient is awake and breathing spontaneously, test the patient’s ability to breathe whilst receiving minimal ventilator support via a spontaneous breathing trial (SBT) using PS/CPAP, FiO2 < 40%, PS 5–10 cm H2O and PEEP 5–10 cm H2O.

If after spontaneous breathing trial, the patient remains stable, there are no signs of respiratory distress and oxygen saturations > 93% with inspired oxygen less than or equal to 60%, the patient’s trachea should be extubated.

If not ready for extubation, then re-assess and repeat SBT as appropriate. If patient continually fails SBT, then discuss with medical team.

To proceed to extubation patients should be:

- Able to follow commands

- Able to protect own airway

- Have adequate strength (e.g. lift head off pillow)

- Have adequate respiratory effort

- Haemodynamically stable

- Bleeding within expected limits (as per local protocol)

- Adequately reversed (neuromuscular blockade)

After extubation, immediately apply high-flow nasal therapy or standard oxygen depending on group allocation.

High-flow nasal therapy

High-flow nasal therapy equipment and disposables should be prepared in advance and checked whilst patient’s lungs still being mechanically ventilated

Start at 40% inspired O2 and flow 30 l/min then up to 50 l/min over 5–10 min. Monitor saturations and RR and arterial gases after 15 min then as per local policy. If saturations < 93%, then increase FiO2 as per respiratory escalation protocol.

Standard oxygen therapy

Start 30–40% inspired O2 and flow 2–6 l/min via nasal prongs or non-rebreathing mask (not humidified and not heated). Monitor saturations and RR and arterial gases after 15 min then as per local policy. If saturations < 93%, then increase FiO2 as per respiratory escalation protocol.

*Ideal body weight is the weight corresponding to an ideal body mass index of 22 kg/m2

Men IBW = (height in metres)2 × 22

Women, IBW = IBW = (height in metres − 10 cm)2 × 22