Heated and Humidified High Flow Oxygen Therapy

This research article was written after a randomized study was done to evaluate the effects that heated and humidified high flow oxygen therapy has on patients that suffer from hypoxemic respiratory failure. In general when a patient is admitted to the hospital and placed on a high flow oxygen device there is no heat or humidity added to the supplemental oxygen the patient is getting. As anyone might imagine breathing in a high flow of cold, dry oxygen could cause real pain and discomfort. In the past there have been multiple studies done on the humidification systems used during endotracheal mechanical ventilation, but few studies have been done on the outcomes of using humidified and non-humidified oxygen therapy on spontaneously breathing patients. The findings from this study as well as a few others that I looked at were quite interesting.

This study was a randomized single-center trial because it was only conducted in one hospital. The randomized trial took place from December 2009 until December 2010 in the medical ICU of Hôpital Henri Mondor in Paris, France. As for how the subjects were chosen it was simple, consecutive patients were included if they required at least 4 L/min of oxygen to maintain a SpO2 above 95%. There was some exclusion criteria put into place; any of the patients that required noninvasive or invasive mechanical ventilation were not really applicable for the study. The patients also had to be in the right state of mind for the study because they would be required to rate the dryness and preference for one of the two oxygen delivery systems. One of the main methods used in monitoring the patients was acoustic rhinometry, it is used to assess whether or not there is any type of nasal airway obstruction. In this case that is something that would possibly make a difference on the level of discomfort a patient could have. The study was set up for the subjects to randomly receive standard oxygen therapy or heated and humidified high flow oxygen therapy (HHFO2) via a nasal cannula for 24 hours and then the patients would be switched to the other device for 4 hours.

The patients were monitored every four hours but because of time and patients getting either worse or better the study was set for 24 hours with the extended switch that took place for 4 additional hours. Initially there were 37 randomized subjects for this study, but 7 of the subjects were unable to complete the study. 5 subjects were dismissed due to the fact that their condition deteriorated while they were in the ICU and they required mechanical ventilation. The other 2 subjects became better and no longer needed to continue on with oxygen therapy that went above 4 L/min. There was a range of ailments amongst the subjects: infectious pneumonia, acute chest syndrome, pulmonary embolism, cardiogenic pulmonary edema, pulmonary hypertension, acute interstitial pneumonia, and hemorrhagic shock. As for the results, it is already known that the group shrank by 7 which leaves 18 in the standard oxygen group and 19 in the HHFO2 group. At hour 0 when the acoustic rhinometry measurements were taken between the 2 groups they had either been placed on 12 L/min if they were in the HHFO2 group and 9 L/min for standard oxygen group, and there were no significant differences. Each group was actually kept at the same oxygen flow throughout the study until the crossover was done.

Initially both groups reported the same dryness scores at the nose, mouth, and throat. As the study moved forward in the fourth hour the standard oxygen group did have a higher median nasal dryness score whereas the HHFO2 group showed a decrease in scores. By hour 28 the crossover was now underway meaning both groups have switched, a large number of subjects preferred HHFO2 over the standard oxygen. Nine of the subjects involved in the study did state that they really didn’t care one way or the other. It should be brought to attention that all of the subjects that prefer the HHFO2 were patients that required the oxygen to be delivered at the higher flow rate. The only complaint about the HHFO2 was the noise that was made by the device. In the end the outcome shows that oxygen therapy delivered to critically ill patients is frequently associated with discomfort, mainly due to nasal dryness. When a high flow of heated and humidified oxygen was given these symptoms were greatly reduced. The study did show that there were no differences between the two groups when it came to measuring the nasal airway caliber.

It seems as though there may have been a lack of information when it comes to the acoustic rhinometry. It is said that the decrease in upper airway dryness may be a contributing factor of diminished upper airway resistance, but because the study did not focus mainly on the acoustic rhinometry measurements or airway resistance this shall remain unknown. As seen in the ICU more times than not patients show discomfort, and this sheer discomfort could be caused by the devices that are helping them get better. The added discomfort a patient feels while in the hospital can sometimes be avoided by something as easy as switching out their standard oxygen therapy for HHFO2 therapy. It was noted that once the subjects had been on HHFO2 therapy they requested to continue on with it even after the study was over. Again, the main disadvantage of HHFO2 that the subjects reported was the noise. The positive way to look at this is that even though there was noise it helped the subjects and the percentage of subjects that preferred the HHFO2 system was greater than those in the standard oxygen group. Out of the entire group only 2 of the subjects complained of the heat generated by the HHFO2 system.

It appears that in the end it was a great success. When I first started to read this case study I felt that I already knew what the outcome would be. It seems as though this would be a common practice. In doing some research for this paper I actually ran across some information where they even questioned just using a bubble humidifier on patients, and that just seemed to be a little on the weird side. I think that if anyone was to place themselves on a nasal cannula and turn it to 10 L/min at that moment they would see the need for heating and humidifying the oxygen. This was really a great study to show something that could easily be done to enhance patient comfort. In researching various websites and even the Egan’s textbook I was unable to find anything showing that there were negative outcomes on humidifying a patient’s oxygen. Actually in every case it showed that the patients experienced less discomfort by having heat and humidification or just humidification alone added to their regular high flow oxygen regimen. At the end of the day I feel it is important to do what is best for the patient, and their comfort or discomfort is part of your problem so all you have to do is fix it. I feel as though adding heat and humidity is an easy fix and I will definitely keep this in mind when tending to patients in the future.

Bibliography

•Kacmarek, Robert M., James K. Stoller, Albert J. Heuer, and Donald F. Egan.
Egan’s Fundamentals of Respiratory Care. 10th ed. St. Louis, MO: Elsevier/Mosby, 2013. Print •http://www.rcsw.org/storage/journal_club/Humidified_HFNC_during_Respriatory_Failure_in_the_ED.pdf •http://www.ncbi.nlm.nih.gov/pubmed/19294365

•Respiratory Care Journal October 2012 Vol. 57 No. 10, http://www.rcjournal.com/ •http://www.vtherm.com/_pdfs/10734_VT_Wpaper_Rev1_v1US.pdf