Assessment of End Expiratory Lung Volumes in Healthy Subjects Using High Flow Oxygen (Vapotherm®)
Respiratory distress is a common problem in an intensive care unit. There are multiple mechanisms that are used to help patients who are in respiratory distress including mechanical ventilation, continuous positive airway pressure (CPAP), bilevel positive airway pressure (BiPAP), high flow oxygen, and oxygen supplementation through nasal cannula or a facemask.
The purpose of this study is to evaluate the mechanism by which Vapotherm, a high flow oxygen system, provides breathing support. Vapotherm provides high flow oxygen at different flow rates, meaning one can increase the amount of oxygen flow to help with breathing support. The investigators believe that this high flow oxygen system may provide similar breathing support that a continuous positive airway pressure machine (CPAP) machine does.
Healthy Adult Volunteers
Device: High-flow nasal cannula oxygen
Device: Facial CPAP
|Study Design:||Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Basic Science
|Official Title:||Assessment of End Expiratory Lung Volumes in Healthy Subjects Using High Flow Oxygen (Vapotherm®)|
- End-expiratory lung volume [ Time Frame: 6 hours ]
|Study Start Date:||July 2012|
|Study Completion Date:||April 2014|
|Primary Completion Date:||April 2014 (Final data collection date for primary outcome measure)|
Experimental: Non-invasive ventilation
Graded high flow nasal cannula oxygen and facial CPAP will be randomly applied to each subject and end-expiratory lung volume measured by respiratory inductive plethysmography.
Device: High-flow nasal cannula oxygen
Graded levels of HFNC will be applied and end-expiratory lung volumes measured by respiratory inductive plethysmography
Other Name: Precision Flow®, Vapotherm®, Stevensville, MDDevice: Facial CPAP
Graded levels of CPAP will be applied by face mask and end-expiratory lung volumes measured by respiratory inductive plethysmography
Other Name: Respironics
High flow nasal cannula oxygen therapy (HFNC) is a method of oxygen delivery now commonly used in persistently hypoxic patients refractory to conventional modes of oxygen supplementation (i.e. nasal cannula, facemask, non-rebreather facemask). Initially used in neonates, it is now increasingly popular in the adult population. While the investigators know how HFNC provides oxygen supplementation, the physiologic mechanism of correcting hypoxemia is still unclear. There are five mechanisms of hypoxemia, four which correct with oxygen supplementation - decreased FiO2, hyperventilation, V/Q mismatch, and diffusion defect; and one that does not - shunt. The hypoxemia refractory to supplemental oxygen suggests the presence of physiologic shunt. The conventional non-invasive therapy to reduce shunt fraction requires raising end-expiratory lung volumes by raising end-expiratory airway pressures using the application of continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP). The Vapotherm® (Vapotherm®, Stevensville, Maryland) product of high flow oxygen therapy (Precision Flow®) is one the investigators frequently use in intensive care units at the University of Maryland Medical Center. It does not create a leak proof seal in the nose as seen in CPAP and BiPAP. Positive pressure generation has been studied in another high flow oxygen system called Optiflow™ (Fisher & Paykel Healthcare, Ltd., Auckland, New Zealand). However this device differs from Vapotherm® in that its nasal bores are large and create a seal in each nares thereby affected both ventilation and the level of PEEP generation. Additionally, these studies measured positive expiratory lung pressures, not volume. Positive end expiratory alveolar pressure and increase expiratory lung volumes in adults have not yet been demonstrated using Precision Flow®.
HFNC is intriguing because studies and clinical data have shown it is a relatively non-invasive method of oxygen delivery that appears to correct hypoxemia better than other non-invasive methods. It is more comfortable than a CPAP machine and thus is better tolerated among patients, especially those who are critically ill and possibly altered. While it has been used in neonates for some time, its use with adults is new and needs more research.
The investigators hypothesis is that HFNC corrects persistent hypoxemia by producing increased end-expiratory lung volumes thus keeping alveoli open throughout the respiratory cycle which other oxygen supplements are unable to do. Using healthy volunteers the investigators will measure end expiratory lung volumes on HFNC and compare them to those obtained with CPAP at graded pressures.
Please refer to this study by its ClinicalTrials.gov identifier: NCT01672242
|United States, Maryland|
|University of Maryland School of Medicine|
|Baltimore, Maryland, United States, 21201|
|Principal Investigator:||Carl B. Shanholtz, MD||University of Maryland|