Bummer

[BlsdMama]

Looks like I was potentially not a limb onset. All that rib pain? Looks like my diaphragm isn’t in lovely shape.

Sigh. Up at Mayo for the day. MIP and MEP values were bad - 28% and 38% respectively. But the FEV/FVC ratio was 85%. So why the bad results in one area but decent in the other? Can so someone explain? I knew this test did not go nearly as well as last time. :/

 

[BlsdMama]

I know some of you understand these tests quite well. So FVC is my forced viral capacity - essentially what my lungs can hold and blow out? So it shows my lungs work well / hold a lot?

Then MEP and MIP show force? Essentially they show the strength the diaphragm can exert to blow the air out? I should think that would impact FVC?

Just wondering how today will go. I knew I was losing ability to push out my voice/breathe, so I’m not surprised to see change. I am surprised at incompatible values?

I know this will impact life expectancy. I do not want a trach. So, my thoughts are around life expectancy because the accelerated death benefits on my policies are all “12 months or less” and I’m not sure how to have that conversation tactfully with my doctor?

 

[KarenNWendyn]

Perhaps Laurie or Nikki will weigh in here.

MIP/ MEP do relate to diaphragm strength. Low values will impact your ability to cough. FVC relates to how much air the lungs can hold and then push out. It can be affected by weakness of the intercostal (rib) muscles, lung stiffness (compliance), posture. I would think poor diaphragmatic strength could impact FVC ultimately, though they might not track together in lock-step.

The low MIP/MEP means you might need a cough assist machine and BiPAP, if you are not already using one. The numbers do impact overall prognosis, but you could still hang in for years. I don’t think one can use the numbers to make a firm statement about how much time one has left.

 

[KarenNWendyn]

I found this information in “UpToDate” which is an online medical textbook:


Comparing measures — The vital capacity (VC) and the forced vital capacity (FVC) are widely used alternatives to the MIP and MEP that are used to follow the disease course. The difference between the VC and the FVC should be clearly understood. The VC is the maximum volume of gas that can be expelled from full inspiration. The FVC is also the maximum volume of gas that can be expelled from full inspiration, but it is measured when the patient is exhaling with maximal speed and effort. The VC is usually higher than the FVC, with the difference being directly related to the degree of obstruction.

Direct comparison of the MIP and FVC demonstrates the following differences:

●When measured in the upright position, a decreased FVC is less specific for respiratory muscle strength (it can also be decreased in interstitial lung disease, chest wall disease, and other conditions) and less sensitive for changes in inspiratory muscle strength, compared to the MIP.

●Because relatively small pressures are required to fully inflate the normal lung the inspiratory muscle can be substantially weakened before the VC is much reduced. The VC falls late in progressive neuromuscular disease like ALS. In contrast, maximum pressure generation falls in line with disease progression.

●A fall in the FVC when the patient moves from the upright to the supine position indicates significant diaphragm weakness more reliably than a low MIP. Significant falls in VC when supine only occur when diaphragm strength is greatly reduced.

Comparison of the MIP and VC demonstrates similar sensitivity and specificity for detecting hypercapnic (high CO2) respiratory failure . Specifically, the MIP had a sensitivity and specificity of 55 and 83 percent, respectively, while the VC had a sensitivity and specificity of 53 and 89 percent, respectively.

Taken together, the data indicate that no single measure is best for assessing respiratory muscle weakness. In our practice, we make clinical decisions after measuring the MIP, SNIP, MEP, and FVC. We measure upright and supine FVC. When doubt persists about whether a patient has respiratory muscle weakness, we perform more complex tests.


(They also note that MIP and MEP are highly impacted by patient effort and ability to form a tight seal on the mouthpiece.)

 

[KimT]

If you have a high total lung volume, your FVC and SVC can be within normal range even though your muscles used for breathing might be weakened.

Did they tell you what your MVV was? That is the amount of air you can move in and out within 12 seconds and some centers consider it one of the most important measurements.

Although the diaphragm controls most of the strength, the intercostal muscles help. So all that rib pain might be from the intercostals working hard.

As you know, the important thing is that you get enough air to feel comfortable while being able to exhale carbon dioxide. So Bipap can do some of the work to help with this.

I routinely measure slow vital capacity (SVC) standing, sitting, and lying flat on my back. Interestingly, I usually get the best number on my back. I also get far better numbers in everything first thing in the morning, on an empty stomach, when I'm rested up.

 

[lgelb]

The percentage of predicted for MIP and MEP are, for purposes of getting a BiPAP reimbursed, not relevant. Your plan will want to see FVC<50% and/or MIP < 60 cm H20. Each of these "blow in/out quickly" type measurements suffers from kind of combining the "quick" part (that you don't need to do in real life when you control your respirations) and the "how much air is in the jar" thing, with other variables of how quickly some muscles mobilize over others, and how well, let's say, your upper abdominals are compensating for a weak diaphragm.

It is also important to note that forced deep breaths may not reflect the reality that a PALS may settle into shallow breathing rather well for long periods of time -- taking in less O2 so as not to need to expel CO2 to the extent as the tests would suggest.

The breathing impairment in ALS is considered "restrictive" in the sense that the muscles don't move as well, but it is also obstructive depending on if/where/how the airway is collapsing. So, yes, the articles continue to suggest that you have to look at everything, but health plans look at certain variables.

If you want to post/send the full list of results, with absolute numbers as well as %s, including height/weight/age, I could be more helpful.

Best,
Laurie

 

[sassy]

I have no medical knowledge to add but love and appreciate the medical support and guidance from the site. Thank you!