Importance of diaphragm thickness in amyotrophic lateral sclerosis patients with diaphragm pacing system implantation.

Introduction: Severe respiratory failure develops as a result of the involvement of the respiratory muscles in patients with amyotrophic lateral sclerosis (ALS). Implantation of diaphragm pacing system (DPS) has been carried out on ALS patients since 2005 to avoid these situations, but the importance of diaphragm thickness has not yet been established clearly.

Material And Method: We retrospectively evaluated 34 ALS patients who had previously implanted DPS to detect the importance of diaphragm thickness. We investigated the effect of diaphragm thickness, which was measured by preoperative thorax computerized tomography on preoperative respiratory function tests (RFT), arterial blood gas (ABG) analysis, postoperative 3- and 6-month oxygen saturations and mortality.

Results: The right diaphragm thickness was calculated as 4.60 (2.95-6.00) mm, while the left diaphragm thickness was 4.10 (2.77-6.00) mm. Six patients died during the follow-up period. We did not detect a significant relationship between ABG parameters, RFT and diaphragm thickness. However, according to our observations, the diaphragm thickness was significantly related to mortality. The right diaphragm was significantly thinner in cases that required preoperative respiratory support and had percutaneous endoscopic gastrostomy. When the cut-off values for the diaphragm thickness were accepted as 3.50 mm, significantly higher mortality among patients below this was observed.

Conclusion: Diaphragm thickness is an important criterion in cases for which DPS implantation is planned. We consider that avoidance of DPS implantation is more suitable for cases with a diaphragm thickness below 3.50 mm because of mortality.