High flow oxygen therapy in obese hospitalised patients: effects on carbon dioxide levels in the blood.

A randomised, controlled crossover trial of the effect of high concentration oxygen on transcutaneous carbon dioxide tension in obese hospitalised patients.

Status

Completed

Phases

Unknown

Study type

Interventional

Source

ANZCTR

Registry ID

ACTRN12610000522011

Enrollment

Registered

2010-06-24

Start date

2011-11-15

Completion date

2015-09-07

Last updated

2021-06-14

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

None listed

Brief summary

Overweight individuals are at increased risk of a number of complications including obesity hypoventilation syndrome (OHS). It has been shown that high concentration oxygen therapy increases arterial carbon dioxide tension (PaCO2) levels in patients with OHS. We now seek to determine whether a similar response occurs in obese subjects, regardless of whether or not they have OHS. This would be relevant to clinical practice as obese patients presenting to hospital with an acute medical condition may routinely given high flow oxygen therapy. This study aims to investigate whether the administration of high concentration oxygen leads to carbon dioxide retention in a group of obese hospital inpatients.

Interventions

Oxygen via face mask at 8L/min for 60 minutes, with recorded measurements of heart rate, respiratory rate, oxygen saturations and transcutaneous carbon dioxide (PtCO2) levels at baseline, 10, 20, 30, 40, 50 and 60 minutes. Subjects will also have these parameters continuously monitored during the intervention, with cessation of the intervention immediately should PtCO2 exceed 10mmHg from baseline

Study design

Allocation

Randomised controlled trial

Primary purpose

Prevention

Eligibility

Sex/Gender

All

Age

16 Years to No maximum

Healthy volunteers

Inclusion criteria

1. Current internal medicine inpatient in Wellington Hospital; 2. Age >/= 16 years; 3. Body Mass Index (BMI) > 40kg/m2.

Exclusion criteria

1. Diagnosis of Chronic Obstructive Pulmonary Disease (COPD); 2. Ratio of Forced Expiratory Volume in one second to Forced Vital Capacity (FEV1:FVC) < 0.7 (First 24 participants recruited only); 3. Patients currently receiving treatment with Continuous Positive Airway Pressure (CPAP) ventilation or Non-Invasive Positive Pressure Ventilation (NIPPV); 4. Patients currently requiring >2L/minute of oxygen therapy following titration to the recommended target saturation range of 88-92% (First 24 participants recruited only); 5. Patients with baseline PtCO2 of >65mmHg; 6. Current diagnosis of disease causing restriction to chest wall expansion, other than obesity i.e. neuromuscular disease or chest wall dysfunction; 7. Administration of respiratory suppressant medications, including opiate analgesia and benzodiazepines within 24 hours (First 24 participants recruited only); 8. Patients with unstable angina or recent myocardial infarction.

Outcome results