Purpose: Patients with a body mass index (BMI) ≥30 kg/m(2) experience more severe atelectasis following cardiac surgery than those with normal BMI and its resolution is slower. This study aimed to compare extubation of patients post-cardiac surgery with a BMI ≥30 kg/m(2) onto high-flow nasal cannulae (HFNC) with standard care to determine whether HFNC could assist in minimising post-operative atelectasis and improve respiratory function.
Methods: In this randomised controlled trial, patients received HFNC or standard oxygen therapy post-extubation. The primary outcome was atelectasis on chest X-ray. Secondary outcomes included oxygenation, respiratory rate (RR), subjective dyspnoea, and failure of allocated treatment.
Results: One hundred and fifty-five patients were randomised, 74 to control, 81 to HFNC. No difference was seen between groups in atelectasis scores on Days 1 or 5 (median scores = 2, p = 0.70 and p = 0.15, respectively). In the 24-h post-extubation, there was no difference in mean PaO2/FiO2 ratio (HFNC 227.9, control 253.3, p = 0.08), or RR (HFNC 17.2, control 16.7, p = 0.17). However, low dyspnoea levels were observed in each group at 8 h post-extubation, median (IQR) scores were 0 (0-1) for control and 1 (0-3) for HFNC (p = 0.008). Five patients failed allocated treatment in the control group compared with three in the treatment group [Odds ratio 0.53, (95 % CI 0.11, 2.24), p = 0.40].
Conclusions: In this study, prophylactic extubation onto HFNC post-cardiac surgery in patients with a BMI ≥30 kg/m(2) did not lead to improvements in respiratory function. Larger studies assessing the role of HFNC in preventing worsening of respiratory function and intubation are required.