A major international trial led by researchers here at Royal Papworth Hospital NHS Foundation Trust has found that standard oxygen therapy is as effective as high-flow nasal oxygen therapy in the recovery of patients who had cardiac surgery.
Professor Andrew Klein, Consultant Anaesthetist at Royal Papworth Hospital and Chief Investigator for the NOTACS study (top left) with colleagues from the NOTACS team
The Nasal Oxygen Therapy After Cardiac Surgery (NOTACS) trial is the largest study of its kind and will now guide best practice worldwide for people having major heart operations. It was NIHR-funded in the UK, with additional support from the Medical Research Future Fund and Heart Lung Foundation in Australia and New Zealand, respectively.
The trial aimed to see if high-flow nasal oxygen therapy (HFNOT) - which sees oxygen gently pumped through the nose post-surgery – led to shorter lengths of stay in hospital for patients and if it reduced readmissions to hospital by preventing chest infections and other respiratory complications, compared to standard oxygen therapy (SOT).
A total of 1,280 adults participated across 17 hospitals in the UK (755 participants), Australia (370) and New Zealand (155). All participants had heart surgery and were randomly assigned to receive either HFNOT or SOT for at least 16 hours after surgery.
HFNOT, which supplies oxygen through nasal tubes worn by patients post-surgery, is a non-evasive form of respiratory support. It is considered more comfortable for patients compared to more invasive alternative therapies. This is because the warm, humidified oxygen does not dry out the airways, and patients are able to talk, eat drink and walk whilst using it.
However, despite patient comfort, the NOTACS results clearly show that high-flow nasal therapy did not improve recovery for patients, compared with standard oxygen therapy:
- Both groups had the same number of days at home without extra help. In fact, most people in both groups needed some help after their surgery. This means the type of oxygen they received didn’t make a difference.
- When looking at time spent at home, both groups did equally well. On average, people in both groups spent about 82 out of 90 days at home in the 90 days after surgery.
- Rates of complications, hospital readmissions, and quality of life were similar between groups.
Figures from the National Institute for Cardiovascular Outcomes Research (NICOR) show that, over the past seven years, an average of 36,505 patients a year underwent cardiac surgery in the UK, with over a quarter (9,500 / 26%) qualified as high risk for postoperative pulmonary complications and prolonged hospital stay.
Professor Andrew Klein, Consultant Anaesthetist at Royal Papworth Hospital and Chief Investigator for the NOTACS study said: “We are delighted that so many patients were willing to take part in this international study.
“The results give us robust evidence that for patients at a higher risk of breathing problems after heart surgery, using high-flow nasal oxygen therapy routinely does not improve outcomes. Standard oxygen therapy works just as well.
“These results provide strong evidence that hospitals should reconsider the routine use of high-flow nasal oxygen therapy with this patient population.
“We are extremely grateful to all our research teams in the UK, Australia and New Zealand for their hard work on this study, which will help guide best practice worldwide.”
The results have since been published in the JAMA Network Open journal.
Some of Royal Papworth’s research team at the Critical Care Reviews annual meeting in Belfast, where they presented on the NOTACS trial
NOTACS was led by Royal Papworth and the Papworth Trials Unit Collaboration, in a collaboration between MRC Biostatistics Unit, the University of Cambridge and King’s College London.
Hospitals in the UK taking part in this research alongside Royal Papworth Hospital NHS Foundation Trust were King's College Hospital, London; Royal Brompton Hospital, London; University Hospital of Wales, Cardiff; Golden Jubilee University National Hospital, Glasgow; St Thomas’ Hospital, London; Glenfield Hospital, Leicester; James Cook Hospital, Middlesbrough; and Queen Elizabeth Hospital, Birmingham.
Hospitals in Australia taking part in this research were Royal North Shore Hospital, Sydney; The Prince Charles Hospital, Brisbane; The Townsville Hospital, Townsville; The Alfred Hospital, Melbourne; University Hospital Geelong, Geelong; Fiona Stanley Hospital, Perth and St John of God Subiaco Hospital, Perth.
Auckland City Hospital was the sole hospital in New Zealand which took part in this research.