I have found a portion of the sleep community that seems to be affected by the association between sleep apnea and the Vagus nerve stimulator. In this portion of the sleep apnea community, there is limited information on how exactly the both of these co-exist. As noted by the NCBI, “Epilepsy and obstructive sleep apnea (OSA) are two relatively common disorders known to coexist and potentially exacerbate each other. Vagus nerve stimulation (VNS) is a currently used, adjunctive treatment for partial epilepsy and is generally well tolerated with few associated side effects.” Most articles that I have found via websites, video blogs, and forums typically only speak of patient comfort while a patient is using positive pressure and a Vagus nerve stimulator. The main study I found, completed by the American Academy of Sleep Medicine, addresses the sleep study positive pressure titration process about the Vagus nerve stimulator. There is very limited information out about the VNS in relation to home positive pressure settings and comfort. Hopefully moving forward this could be addressed by the sleep industry, providers, and patient community. However, in the meantime, I wanted to put together a brief article on a trend I have found and suggestions for patient’s that are possibly using VNS and positive pressure therapy!
To be upfront, and clear. I am a sleep technologist – I am not a physician. So my findings are by looking into the subject via journals, speaking with others, and questioning sleep physicians on the subject to have a better understanding. Although it seems that VNS is something that is not as common as sleep apnea, there are still positive pressure users that must use both of these in unison. And I feel there may be a small oversight in a particular area when addressing sleep apnea and the use of VNS – hence what has urged me to put together a quick article. The urge in the subject matter for me to look into the subject and understand more is in the relation with lower airflow and breathing after a VNS device is used. As stated from the case study completed by the American Academy of Sleep Medicine, “In their initial study, they found that patient with VNS had lower airflow and breathing effort after VNS devices were implanted. This was seen during almost every “one” cycle of the devices.” As with anything involving positive pressure therapy, there are million different type of comfort characteristics that can be addressed here. The one that I feel may be overlooked (and is critical to patient compliance and understanding) is whether or not auto continuous positive airway pressure (APAP) or continuous positive airway pressure (CPAP) should be used for VNS patients.
In this sleep study, the patient was titrated with both the VNS turned on for one study and another titration study when the VNS device was turned off. The patient was placed on CPAP with the VNS on and off then the two studies were compared to review which study was the most effective. The physicians found that the VNS device should be turned off for the study to produce accurate results.
Now! That last two paragraphs could have been a completely foreign language to you, or you may better understand everything better than myself (if you do, please leave a comment!). Here is where my little two cents on the subject matter become evident. During a sleep study a trained technologist is reviewing information to assure that the patient is accurately asleep and whether or not CPAP is needed; and if CPAP is needed, then a trained technologist is going to change pressures slowly to find an accurate pressure. So, once again a trained individual is making this call, and when a VNS device is in place, it is obvious that particular apnea events may not be true. However, if a machine were monitoring that patient without all of this information the indication of an apnea being true, or not, would likely not be recognized.
My experience with a VNS about auto-CPAP. If a VNS device is turned on and the patient is wearing automatic positive pressure (auto-CPAP), then the machine may increase the patient’s pressure incorrectly when it is not needed; this could impact the patient’s comfort, compliance, and adherence to the therapy. Here is the example. If a patient is set to a pressure setting of 5 cm/H2O to 15 cm/H2O auto CPAP with a Vagus nerve stimulator turned on, then it is highly likely that the patient will be titrated (praised raised/lowered) to the max pressure setting of 15 cm/H2O due to the VNS device causing restricted breathing patterns and apneic events when more pressure may not be actually needed. Now, I believe it could be argued that a patient may need more pressure to clear this actual event, but the fact is that these events are not true (per the clinical case study referenced).
So, this presents the question that if you are a CNS patient is automatic CPAP the best treatment option for you? It seems that this answer is no. The reasoning is simple. If a patient has the VNS turned off for a titration sleep study and an optimal pressure is attained during this study, then it would be likely that the positive pressure found in the study should be used. For example, if your study states that the best pressure for you was a pressure of 8 cm/H2O then that is likely what your machine should be set to avoid further problems. If you use an auto CPAP at pressures of 7-11 cm/H2O, then you are inevitably going to reach 11 cm/H2O with the VNS device turned on and using a pressure that is not needed.
My reasoning for this conclusion is based entirely for comfort. You may be a patient that can tolerate more pressure and feel that auto CPAP would be the best treatment option, in that matter it is your choice. I cannot find any case studies done to argue otherwise. However, it can be stated that you are using a pressure that was not found to be the truly optimum pressure in a sleep laboratory.
Overall, in my own opinion you should still attain an auto CPAP machine from your provider or privately and simply have it set to your CPAP settings. Not an Auto-CPAP settings. The only reason for this is simple, if you get an auto CPAP unit then you the data can be download from within it and reviewed where a lesser unit may not offer this option. It is also likely that if a VNS device is being used then the CPAP user is likely a patient of a neurologist and the physician will be aware of false apnea events indicated by the positive pressure unit.
It turns out that my two cents were slightly longer than expected on this particular subject! I know this is a bit longer than expected, but I hope there is some information within that reach someone that may be seeking to shed some light upon the subject matter!
Ebben MR; Sethi NK; Conte M; Pollak CP; Labar D. Vagus nerve stimulation, sleep apnea, and CPAP titration. J Clin Sleep Med 2008;4(5):471–473.