High Flow Oxygen Therapy and the PMV®
Lynn Godwin, BSRT, RRT
A frequent question that has arisen from clinicians is: What is High Flow Oxygen Therapy, and should I be using it with my patients who have a Passy Muir® Valve (PMV®)? This article begins to address the considerations by providing information on both devices and the current state of the science. First, High Flow Oxygen Therapy (HFOT) is an oxygen delivery system which provides heated humidity with high flow levels of oxygen (O2). Traditional oxygen delivery systems do not exceed 16 L/min while HFOT can deliver up to 60 L/min and as high as 100% oxygen (Lindenauer, et al., 2014; Gotera, Díaz Lobato, Pinto, & Winck, 2013). HFOT is typically used with patients following acute respiratory failure; however, it has proven to be successful in decreasing the Work of Breathing (WOB) in chronic conditions, such as Chronic Obstructive Pulmonary Disease (COPD) and end-stage cancers as well (Gotera et al., 2013).
The HFOT system essentially creates an oxygen reservoir within the patient’s airway, decreasing the patient’s WOB due to the available O2 during inhalation (Dysart, Miller, Wolfson, & Shaffer, 2009). In addition, the high turbulent flow flushes the anatomical dead space, removing the remaining exhaled air, thereby, rapidly clearing carbon dioxide (CO2) (Dewan & Bell, 1994). The heated humidification component provides warm moisture to the airway, preventing drying of the mucous membranes, while at the same time assisting with decreasing the viscosity of mucous in the airways (Dysart, et al., 2009).
In addition to these benefits, the increasing use of HFOT is partially attributed to the comfort of the patient interfaces. The nasal cannula interface is more comfortable for the patient than wearing facial mask O2 delivery systems (Dysart, et al., 2009). The patients who benefit from HFOT include both the adult and pediatric patient. It also can be provided to tracheostomy patients to provide support for respiratory function.
Studies have shown that HFOT produces a Positive End Expiratory Pressure (PEEP) effect within the lungs, improving lung recruitment and thus improving oxygenation, as well as decreasing the risk for atelectasis (Gotera, et al., 2013). Use of the Passy Muir Tracheostomy & Ventilator Swallowing and Speaking Valve® (PMV®) also has been shown to assist with lung recruitment, diaphragm function, and improved ventilation of the alveoli (Sutt, Caruana, Dunster, Cornwell, & Fraser, 2015). Some facilities have reported using the HFOT with tracheostomy in conjunction with a PMV because of the potential for lung recruitment to be further enhanced with the restoration of more natural physiological PEEP with use of the Valve. The potential dual benefit from using both the HFOT and the PMV provide some support for using these two options together as an intervention.
Since studies also have shown that HFOT may reduce exercise-induced dyspnea allowing for patients’ endurance levels to be increased (Dewan & Bell, 1994), and because the PMV restores a patient to a closed system with exhalation through the upper airway, increased thoracic pressures are possible which may further improve postural control and stability when the two devices are used together. This in turn may provide a stronger, more stable core for physical movements and interventions. Both HFOT and the PMV also have been shown to improve secretion management. Because both devices have been shown to have effects that benefit a patient on several levels, healthcare professionals are looking more toward using them together. The facilities that are doing so report positive effects; however, research is needed to investigate the premise of multiple benefits from using HFOT with the PMV in appropriate patient populations.
Dewan, N.A. & Bell, C.W. (1994). Effect of low flow and high flow oxygen delivery on exercise tolerance and sensation of dyspnea. A study comparing the transtracheal catheter and nasal prongs. Chest, 105(4), 1061-5.
Dysart, K., Miller, T.L., Wolfson, M.R., & Shaffer, T.H. (2009). Research in high flow therapy: mechanisms of action. Respiratory Medicine, 103(10), 1400-5.
Gotera, C., Díaz Lobato, S., Pinto, T., & Winck, J.C. (2013). Clinical evidence on high flow oxygen therapy and active humidification in adults. Pulmonology Journal (Revista Portuguesta de Pneumologia), 19(5), 217-227.
Groves, N., & Tobin, A. (2007). High flow nasal oxygen generates positive airway pressure in adult volunteers. Australian Critical Care, 20(4), 126-131.
Lindenauer, P.K., Stefan, M.S., Shieh, M.S., Pekow, P.S., Rothberg, M.B., & Hill, N.S. (2014). Outcomes associated with invasive and noninvasive ventilation among patients hospitalized with exacerbations of chronic obstructive pulmonary disease.
JAMA Internal Medicine, 174(12), 1982-93. Ritchie, J.E., Williams, A.B., Gerard, C., & Hockey, H. (2011). Evaluation of a humidified nasal high-flow oxygen system, using oxygraphy, capnography and measurement of upper airway pressures. Anaesthesia Intensive Care, 39(6), 1103-1110.
Sutt, A., Caruana, LR., Dunster, K. R., Cornwell, P. L., & Fraser, J. F. (2015). Improved lung recruitment and diaphragm mobility with an in-line speaking valve in tracheostomised mechanically ventilated patients – an observational study. Australian Critical Care, 28(1), 45. doi:10.1016/j.aucc.2014.10.021