Identification of unexpected respiratory abnormalities in patients with amyotrophic lateral sclerosis through electromyographic analysis using intramuscular electrodes implanted for therapeutic diaphragmatic pacing

http://www.americanjournalofsurgery....598-4/fulltext

selected excerpts:
"Control of respiration is incompletely understood in normal subjects and even less in ALS. . . .

"Some patients had minimal or absent dEMG activity but strong diaphragm contraction when the electrodes were stimulated. . . .

" . . . With disuse, the intact motor units of the diaphragm will rapidly convert to Type IIb fast-twitch muscle fibers . . . .

" . . . There is a growing evidence that ALS patients have sleep-disordered breathing that is most often because of central mechanisms. . . .

". . . dEMG burst activity improved for some patients after DP conditioning or a rhythmic breathing pattern would continue when DP was not being used. Fig. 1 highlights the dEMG improvement in burst activity. . . .

". . . DP may improve automatic respiratory control. . . .

". . . Death can occur within hours of DP withdrawal indicating that there can be a rapid loss of control leading to respiratory failure with DP cessation. . . .

"(evidence of) NIV causing diaphragm activitiy suppression; (4) identification of unilateral abnormalities with a loss of control of the diaphragm from respiratory control centers in the brainstem; (5) DP improves diaphragm burst activity and helps in maintaining the respiratory pacemaker. . . .

"(DP may) also delay the death of those motor neurons. . . .

"The fifth finding is a growing area of research in respiratory physiology. There is evidence that the respiratory system is able to "fight back" and trigger spontaneous compensatory plasticity that can maintain respiration in the face of motor neuron loss. . . .

"The plasticity although somewhat persistent was shown to wane when DP is discontinued. For example, in one case a patient with DP became intubated secondary to aspiration pneumona and DP was stopped for several days at an outside hospital. Prior to the event the patient had large dEMG burst activity and was using DP as the primary mode of ventilation even though he was late in his disease. When re-evaluated, the patient had no dEMG volitional burst activity and DP could no longer maintain ventilation. The plasticity seen from DP may rapidly degenerate when DP is stopped in ALS patients. . . .

"Because DP prevents diaphragm atrophy from NIV suppression, DP can decrease the need for NIV during the day. . . .

"If the dEMG shows no burst activity but the diaphragm was stimulable then the patient requires 24 hours pacing to maintain diaphragm function. . . .

"DP therapy is optimum when the patient has unused motor units that DP can drive and dEMG shows the patient has instability of control of those units. . . .

"In conclusion, these dEMG findings demonstrate that ventilatory dysfunction in ALS is likely much more complex than just denervation atrophy of the diaphragm. Significant areas of central dysregulation were seen along with interesting observations of apparent asymmetric central dysfunction."

Onders recommends patients should have DP active whenever they are on BiPAP . . . "We've now realized that just being on the ventilator in your intensive care unit, if you get pneumonia, actually changes your brain stem control of respiration. There's actually adverse effects in your pre-Botzinger complex."