High flow nasal oxygen is a good option for palliative patients

If I wasn’t an emergency doctor, there is no doubt that I would be in palliative care. Therefore, high quality palliative care in the emergency department is a bit of a soapbox issue for me. When I originally wrote my approach to palliative dyspnea, I said that high flow humidified nasal (HFNC) oxygen made a lot of sense to me, but that the evidence is limited, and the practice is often hampered by some silly hospital rules. There is now an RCT that, although imperfect, should encourage adoption of this practice if you are not already using it. 

The paper

Ruangsomboon O, Dorongthom T, Chakorn T et al. High-Flow Nasal Cannula Versus Conventional Oxygen Therapy in Relieving Dyspnea in Emergency Palliative Patients With Do-Not-Intubate Status: A Randomized Crossover Study. Ann Emerg Med. 2020 May;75(5):615-626. doi: 10.1016/j.annemergmed.2019.09.009. PMID: 31864728

The Methods

This is a randomized, nonblinded, AB/BA crossover trial comparing conventional oxygen therapy and high-flow nasal cannula.

Patients

Adult patients presenting to the emergency department with hypoxemic respiratory failure with a known palliative / do-not-intubate status.

• Patients were excluded if they had altered mental status.

Intervention

High-flow nasal cannula (treatment B) by an OptiflowTM cannula using an AIRVOTM2 humidified high-flow system for 60 minutes. The flow rate was set at 35 L/min and adjusted it to between 30 and 60 L/min to improve the participant’s comfort. FiO2 was adjusted to maintain an oxygen saturation greater than 95%.

Comparison

Conventional nonrebreather for 60 minutes. The flow rate was adjusted to maintain an oxygen saturation greater than 95%.

Patients were randomized as to which therapy they started with, but then after one hour were immediately switched to the opposite therapy. 

Outcome

The primary outcome was patient reported dyspnea on the modified Borg scale.

The Results

They included 48 patients. The mean age was 60, and more than 90% were palliative due to a malignancy. The mean modified Borg scale (a 0-10 scale, with 10 being the most dyspnea) was 8 at the time of enrollment.

After 60 minutes, both therapies resulted in decreased dyspnea on the modified Borg scale, but the HFNC groups had lower average scores (2.9 versus 4.9, mean difference 2.0, 95% CI 1.4 to 2.6). The results were similar at 30 minutes.

Objective measures such as respiratory rate and pulse-oximetry were also better in the HFNC group. Use of morphine was also lower in the HFNC group. 

My thoughts

Obviously, there are significant limitations to a non-blinded study of only 48 patients.

Like many studies, selection bias is a big concern. They had to screen 828 patients to find 48 that fit their criteria. I think it is very understandable in this study, because it is very difficult to find palliative patients how are objectively hypoxic, but don’t have an altered mental status. Those criteria are probably important for research purposes, but I doubt they matter clinically. As long as you are providing other proven therapies, like morphine, I think it is reasonable to extrapolate these results to patients with altered mental status as well.

Unblinded trials with subjective outcomes are always concerning for bias, especially when comparing ‘fancy new tech’ to older familiar therapies. In palliative care, the subjective outcomes are all we care about, and there may be some role for the placebo effect, but we still want our science to give us real answers. I don’t know how I would blind this research, and I the benefit in objective measures like respiratory rate are reassuring. 

This study take place in Thailand, so the underlying pathology is probably somewhat different that I am used to in Canada, and it would be great to see the study replicated. However, I can’t think of any reason that HFNC would be worse in my population. 

I am not very familiar with the Borg score, and the authors don’t discuss what would be considered the minimal clinically important difference. A 2 point differences seems like it would matter, but could be heavily influenced by things like the reliability and validity of the scale.

One thing that I love about palliative care is that n of 1 trials are always reasonable. You can try a treatment, and because the only outcome you care about is patient comfort, you can get immediate feedback on whether you should continue the therapy or not. (Do you think this is helping you? Do you want to continue?) Therefore, our job is less about measuring the benefits, and more about considering the harms we might be causing. HFNC is relatively safe, but it is worth noting that 4% (or 2 patients) could not tolerate HFNC, and 5 other reported discomfort with it. However, 78% of patients decided to continue with HFNC for their admission after the trial was over, which might be the most important outcome in a palliative care trial.

I still wonder about the role of noninvasive positive pressure ventilation in the management of palliative patients. It is a proven therapy in many of the conditions that these patients present with. It could completely reverse an exacerbation without requiring more invasive therapy, which is often entirely within the goals of care for these patients. Highflow nasal cannula are better in many ways, in that they are probably more comfortable, and allow for conversation, eating, and drinking. However, there may also be advantages to NIPPV. I wish this trial had included a third arm, in which patients received NIPPV, because I think that would be very valuable information. Hopefully we will see more research on the topic. (These authors do reference a prior RCT that found that HFNC was non-inferior to NIPPV.) (Hui 2013)

In my experience, the big problem with using high flow oxygen devices in palliative patients is silly hospital rules that require patients on HFNC to go to the ICU. If you are using HFNC as a temporizing measure to avoid intubation in non-palliative critically ill patients, of course the ICU is the correct location. But it doesn’t make any sense for palliative patients. These patients are not going to have their care escalated, even if they ‘fail’ HFNC. There is absolutely no reason for them to be in the ICU, and there is absolutely no reason for hospitals to have rules like this in place. Administrators need to understand that these rules result in worse patient care, and should be eliminated immediately.

Bottom line

There are significant limitations to a small, unblinded, single centered study. However, the expected costs (assuming you already have these devices) and harms are very low, and the benefits can be immediately assessed for the patient in front of you. Therefore, this is enough evidence to support using high flow humidified nasal cannula for palliative care patients, if that is not already your practice.. 

Other FOAMed

Palliative resuscitation: Managing dyspnea in emergency department palliative patients

References

Hui D, Morgado M, Chisholm G, Withers L, Nguyen Q, Finch C, Frisbee-Hume S, Bruera E. High-flow oxygen and bilevel positive airway pressure for persistent dyspnea in patients with advanced cancer: a phase II randomized trial. J Pain Symptom Manage. 2013 Oct;46(4):463-73. doi: 10.1016/j.jpainsymman.2012.10.284. PMID: 23739633

Ruangsomboon O, Dorongthom T, Chakorn T et al. High-Flow Nasal Cannula Versus Conventional Oxygen Therapy in Relieving Dyspnea in Emergency Palliative Patients With Do-Not-Intubate Status: A Randomized Crossover Study. Ann Emerg Med. 2020 May;75(5):615-626. doi: 10.1016/j.annemergmed.2019.09.009. PMID: 31864728