Novel use of high-flow nasal oxygen to enable physiotherapy-led exercise in patients with severe hepatopulmonary syndrome before and after liver transplantation: a prospective case series

Background

Patients (pts) with severe hepatopulmonary syndrome (HPS) awaiting liver transplantation (LT) have reduced exercise capacity and progressive physical frailty due to brittle platypnea and orthodeoxia. Despite the use of ward-based conventional oxygen therapy (i.e. maximum flow rate 15L/min), capacity to exercise safely is limited secondary to lung shunting and acute oxygen (O2) desaturation (SaO2<80%). Our prospective case study aimed to assess the efficacy and feasibility of high flow nasal oxygenation (HFNO; up to 100% O2 with flow rate 30–60L/min) to facilitate physiotherapy-led exercise in patients with HPS.

Method

Training in ward-based HFNO was delivered to specialist liver physiotherapists. Moderate intensity (Borg rate of perceived exertion (RPE) 12–14), aerobic (walking, spot march, step-ups) and resistance (free/body weight, TheraBand©) inpatient exercise sessions were delivered to pts with severe HPS pre-and post-LT. Exercise session completion was defined as ability to maintain RPE 12–14 and O2 saturations ≥90% when using conventional oxygen therapy or HFNO. Time to mobilise (edge sit, step transfer, walk >3 m, >30 m) post-LT, freq. exercise session completed, O2 required to complete exercise session, and liver frailty index (LFI) pre-and post-LT were observed.

Results

3 pts (2 F:1 M; age 29–45 yrs) with severe HPS (defined as PaO2 on room air (RA) <60 mmHg/8kPA) were studied pre-and post-LT. Average resting O2 requirements were 65% at 10L/min with conventional O2 therapy pre-LT. Median number of pre-LT completed exercise sessions were 5 (interquartile range (IQR) 3.5–10), median 50% O2 (IQR 43–65%) and flow rate 59L/min (IQR 45–60). Median number of post-LT completed exercise sessions were 35 (IQR 34–37), with median requirement of 60% O2 (IQR 55–70) and flow rate 50L/min (45–55). Median days post-LT using conventional O2 therapy vs. HFNO to edge sit, step transfer and walk>3 m was 14 (IQR 11–48) vs. 6 (IQR 5–10), 84 (IQR 46–117) vs. 6 (IQR 5–17) and 111 (IQR 58–113) vs. 7 (IQR 6–28), respectively (table 1). Physiotherapy-lead exercise improved LFI in two of the three patients from 5.13 to 4.70 pre-LT, and from 4.51 and 3.78 at the point of hospital discharge post-LT (length of stay 304 and 162 days respectively).

Conclusion

HFNO safely enables physiotherapy-lead exercise in pts with severe HPS pre and post-LT. HFNO-assisted exercise accelerates ‘time to mobilise’ post-LT compared to conventional O2 therapy and improves physical frailty.