By Dr. Bastian M.D.
A few times a year, distressed patients present from their internists or pulmonologists to see if I can explain their shortness of breath. The patient has already undergone numerous tests: e.g. chest x-ray, pulmonary function tests, EKG, stress test, echocardiogram, CT, blood tests, and even bronchoscopy. Everything has come back normal, or anything even slightly abnormal (the reader can fill in the blank) has been treated maximally without any reduction of the patient’s symptoms.
In short, the patient has complied with every test and treatment recommendation; yet there is still no apparent explanation for this difficulty breathing, and no relief provided by numerous treatment trials.
The patient seems weary of the problem. My “antennae” do not pick up any signals of la belle indifference (a peculiar lack of concern about symptoms that when present suggests that the problem may be non-organic). She tells me that her breathing is never noisy, and that her shortness of breath may or may not be associated with exercise. I apply my subjective but extremely useful “flow-volume loop” by asking her to exhale to “empty” and then rapidly breathe in until completely full, and there is no unusual noise, and no prolongation of the time required to fill.
My initial thought in this scenario? The gasping syndrome. What is that? A recognizable but to my knowledge previously undescribed disorder. Here is my composite description, meaning that individual patients may not fit every element of what follows:
- Either with exertion or at rest, the patient has an abrupt* sense of “smothering,” or air hunger. It happens almost from one second to the next. Like the abrupt shooting pain of neuralgia, the abrupt tickle of sensory neuropathic cough / throat clearing, or the abrupt laryngeal closure of laryngospasm. The patient says she can be engrossed in a movie or a book strolling with the dog when suddenly her consciousness is invaded by a need to “get more air.”
- She responds by taking a deep breath, but there is no relief and the sensation remains. So, she takes a series of deep breaths, all of them to no avail. The feeling is oppressive, anxiety-provoking, gasping. This sensation may last for a few seconds, to several hours.* Unfortunately, it can happen again some time later, or maybe just a time or two per day or even per week.
Having seen many people who fit the gasping syndrome across the decades, though not usually more than a handful per year, I have speculated that this is a sensory disturbance. After all, I ponder, if it represents more than a primary neuropathic sensation, why is oxygen saturation measured by oximetry, including during exercise, always normal? Why are all the tests of heart and lung function normal? Why no mitral valve prolapse, or something to explain this? Why nothing on imaging? Why no noisy breathing?
My mind goes to patients who describe a similar sensation at the moment IV contrast is injected for a CT scan. In addition to “warmth,” “a sensation of needing to urinate,” etc., they can have a sensation of abrupt, quite compelling, and thankfully transient smothering. Or to someone I know who in the middle of an IV infusion of a biologic modifier for cancer, (with prior warning) experienced profound air hunger that started abruptly and was completely gone 20 seconds later. In each of these cases, it seems like a primary sensory phenomenon more than an alerting and protective sensation in response to low oxygen or high carbon dioxide levels.
How would one conceptualize a mechanism? Here is one thought experiment: consider that we are all supplied with pulmonary stretch receptors. They send messages “in the background” several times across the day and night to the respiratory center: Excuse me… Take a deep breath; expand those alveoli; your surfactant is giving you some atelectasis. And so, without being aware of it, we sigh now and then. We roll over in our sleep, mutter, grind our teeth, and take a deep breath. While reading a book we subconsciously shift in our seat and inspire deeply as we turn a page. Again, we are unaware of this, but an observer watching us read or, equipped with night vision goggles and watching us sleep, will see it.
What if the pulmonary stretch receptors send a signal Hey! Time to take a deep breath! and despite our taking a deeper breath outside of conscious awareness, the respiratory center does not receive the return communication, Action completed. Even with normal O2 and CO2 levels, if the brain thinks that deep breath did not happen, would it not intrude on conscious thought to re-command more urgently: Hey! Deep breath please!
Where does one go to help the patient with this thought experiment diagnosis? Just give her this explanation and leave it there? Or, maybe punt back to the primary care or pulmonary or cardiology physician…? But what if the person has already seen 3 of each specialty—one who is local, another at a nearby university center, and a third at a national referral center? What if “every conceivable test” has already been done 3 times?
A follow-on thought experiment: to the patient, and via a summary letter to her doctors, explain the concept of dysesthesia or sensory disturbance. Give her analogies: at the dentist, after anesthesia is in place to allow that root canal or filling, your tongue/lip can feel swollen, but a look in the mirror shows them to be normal. When a leg goes to sleep, it can feel fatter and heavier than the other one, but it is not. When you suffer nerve damage from diabetes, it can feel like bees are stinging your feet, but none are present in the room.
And then explain scenarios where persons have to accommodate to or neglect the feeling of contact lenses. The sound of new tinnitus. The tickling of an indwelling tracheotomy tube. The dramatic sensation a sword swallower must ignore during the show. Or the sensation of air hunger the pearl diver must overcome to stay submerged for 2 minutes while swimming vigorously.
Perhaps point out that it appears there is no danger from this ominous-feeling sensation. Remind her of the multiplicity of prior “normal” tests. Maybe suggest that she experiment with assuming “control” of her response to the sensation by saying to herself: It is just a feeling! Or, Stupid pulmonary stretch receptors! Maybe gently alter behavior to see if it has any impact. Introduce inspiratory resistance via “straw-breathing.” Or a gentle Valsalva maneuver. Or, exhale slowly through pursed lips whose opening is the size of a coffee-stirrer.
And if nothing else works, suggest trying to mentally shrug and “throw the sensation over the shoulder.” And then keep going. The very worried individual can purchase an oximeter. Or even a stethoscope as a “crutch” to allay anxiety.
All of this can be offered with a physician’s apologies that he or she has nothing better to offer. And also with encouragement that these ideas have “liberated” other patients struggling with the same problem.
A final thought: just as neuromodulators can help persons suffering from neuralgia or sensory neuropathic cough/throat clearing, and laryngospasm, consider a “sensory neuropathic cough” strategy of working one-by-one, from medication to medication such as amitriptyline, gabapentin, etc., hoping to find one that helps.
*Some describe a more continuous, lower-grade background sensation of difficulty breathing with abrupt “peaks”
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