These findings are consistent with research from behavioural economics and psychology that suggests judgement tends to be relative in nature. Observing that the valence of narrative comments is similarly influenced suggests these effects represent more than difficulty in translating impressions into a number. The extent to which such factors impact upon assessment in practice remains to be determined as the influence is likely to depend on context.

Background: Iatrogenic hyperoxaemia is common on critical care units and has been associated with increased mortality. We commenced a quality improvement pilot study to analyse the views and practice of critical care staff regarding oxygen therapy and to change practice to ensure that all patients have a prescribed target oxygen saturation range. Methods: A baseline measurement of oxygen target range prescribing was undertaken alongside a survey of staff attitudes. We then commenced a programme of change, widely promoting an agreed oxygen target range prescribing policy. The analyses of target range prescribing and staff survey were repeated four to five months later. Results: Thirty-three staff members completed the baseline survey, compared to 29 in the follow-up survey. There was no discernible change in staff attitudes towards oxygen target range prescribing. Fifty-four patients were included in the baseline survey and 124 patients were assessed post implementation of changes. The proportion of patients with an oxygen prescription with a target range improved from 85% to 95% ( 2 ¼ 5.17, p ¼ 0.02) and the proportion of patients with an appropriate prescribed target saturation range increased from 85% to 91% ( 2 ¼ 1.4, p ¼ 0.24). The improvement in target range prescribing was maintained at 96% 12 months later. Conclusions: The introduction and promotion of a structured protocol for oxygen prescribing were associated with a sustained increase in the proportion of patients with a prescribed oxygen target range on this unit.

Iatrogenic hyperoxaemia is common on Critical Care Units (CCUs) throughout the world and high blood oxygen levels have been associated with adverse outcomes including increased mortality. We have commenced a pilot quality implementation study to analyse the views of Critical Care staff regarding oxygen therapy and to change practice to ensure that all patients in the Critical Care Unit have a prescribed target oxygen saturation range. 33 CCU staff responded to an online questionnaire (16 doctors, 7 nurses, 9 physiotherapists, 1 ACCP). 76% thought that slightly too much oxygen was used on the unit but only 53% favoured a formal prescription for oxygen for all patients. For ventilated patients not at risk of hypercapnia, 83% would favour a target range of 94%–98% and 10% would opt for a target range of 90%–94%. For patients at risk of hypercapnia, all respondents favoured a target range of 88%–92%. A baseline audit of practice on the unit studied 54 patients (28 on ventilators) over one month prior to the implementation of a programme of change. 85% of audited patients (46 of 54) had a formal oxygen prescription with target range. Forty patients had target range 94%–98% and six patients had target range 88%–92%, all prescriptions were judged to be appropriate. The mean PaO2 on blood gas samples was 13.1 kPa compared with 15.1 kPa in 2005 and 14.9 kPa in 2010. Mean PaCO2 was 5.3 kPa. The mean SpO2 (pulse oximetry) was 96.8% [median 97%, range 91%–100%]. 82% of SpO2 values were within the target range but four of six patients with target range 88%–92% were at least 2% above this range. Attitudes and practice in our Critical Care Unit have changed in the past decade and hyperoxaemia is less common now. However, practice still lags behind the declared ambition of our Critical Care colleagues to maintain normoxaemia for most patients. We have instituted changes to CCU practice in May-June 2017. These changes will inform the design of a systematic randomised cluster implementation study using a step-wedge design to implement current best practice in a wide range of Critical Care units.