High flow or titrated oxygen for obese medical inpatients: a randomised crossover trial

• Published in: Medical journal of Australia Vol. 207; no. 10; pp. 430 - 434
• Main Authors: Pilcher, Janine, Richards, Michael, Eastlake, Leonie, McKinstry, Steven J, Bardsley, George, Jefferies, Sarah, Braithwaite, Irene, Weatherall, Mark, Beasley, Richard
• Format: Journal Article
• Language: English
• Published: Australia 20-11-2017
• Subjects: Adult; Aged; Blood Gas Monitoring, Transcutaneous; Cross-Over Studies; Female; Hospitalization; Humans; Hypercapnia - etiology; Hypoxia - complications; Hypoxia - therapy; Male; Middle Aged; Obesity, Morbid - complications; Oxygen Inhalation Therapy - adverse effects; Oxygen Inhalation Therapy - methods; Respiratory tract diseases; Oxygen delivery; Obesity; Lung diseases
• ISSN: 0025-729X; 1326-5377
• DOI: 10.5694/mja17.00270

Objective: To compare the effects on transcutaneous carbon dioxide tension (Ptco2) of high concentration and titrated oxygen therapy in medical inpatients with morbid obesity who were not selected for a pre‐existing diagnosis of obesity hypoventilation syndrome.
Design: A randomised, crossover trial undertaken between February and September 2015.
Setting: Internal medicine service, Wellington Regional Hospital, New Zealand.
Participants: 22 adult inpatients, aged 16 years or more, with a body mass index exceeding 40 kg/m2.
Interventions: Participants received in random order two 60‐minute interventions, with a minimum 30‐minute washout period between treatments: titrated oxygen therapy (oxygen delivered, if required, via nasal prongs to achieve peripheral oxygen saturation [Spo2] of 88–92%), and high concentration oxygen therapy (delivered via Hudson mask at 8 L/min, without regard to Spo2). Ptco2 and Spo2 were recorded at 10‐minute intervals.
Main outcome measure: Ptco2 at 60 minutes, adjusted for baseline.
Results: Baseline Ptco2 was 45 mmHg or lower for 16 participants with full data (73%). The mean difference in Ptco2 between high concentration and titrated oxygen therapy at 60 minutes was 3.2 mmHg (95% CI, 1.3–5.2 mmHg; P = 0.002).
Conclusion: High concentration oxygen therapy increases Ptco2 in morbidly obese patients. Our findings support guidelines that advocate oxygen therapy, if required in patients with morbid obesity, be titrated to achieve a target Spo2 of 88–92%.
Clinical trial registration: Australian New Zealand Clinical Trials Registry, ACTRN12610000522011.