Functional state of the diaphragm in patients with cervical spinal cord injury at the stages of respiratory support

Abstract

Objective. To analyze the role of the functional state of the diaphragm in patients with cervical spinal cord injury at the stages of respiratory support and to substantiate additional criteria for their readiness to transfer to spontaneous breathing.Material and Methods. The state of the diaphragm was assessed by ultrasound in 24 patients with spinal cord injury. The excursion of the diaphragm during quiet breathing, the excursion and thickness of the diaphragm during forced breathing, and the change in forced expiratory volume from the moment of admission till the end of mechanical ventilation were analyzed.Results. On the first day, on the background of mechanical ventilation, there was a significant decrease in the excursion and thickness of the diaphragm during forced breathing (p = 0.002; p = 0.008) which persisted up to 3 days (p < 0.001; p < 0.001); by the fifth day of mechanical ventilation, the indicators increased to the initial levels (p = 0.112; p = 0.433); and by the 10th day they exceeded the initial values (p < 0.001). When comparing the excursion and thickness of the diaphragm during the transfer of patients to spontaneous breathing with the data on their admission, a significant difference was obtained (p < 0.001; p < 0.001). The dynamics of forced expiratory volume indicators was similar to those of diaphragm excursion during forced breathing.Conclusion. A peculiarity of the functional state of the diaphragm in patients with cervical spinal cord injury in the acute period was a significant decrease in diaphragm excursion and the development of ventilator-induced diaphragm dysfunction (VIDD) associated with mechanical ventilation in replacement modes. The tactics of early tracheostomy and the use of auxiliary ventilation modes determined the absence of progression of VIDD during prolonged mechanical ventilation. The presence of a strong correlation between the diaphragm excursion during forced breathing and the forced expiratory volume allows concluding that these indicators can be additional objective criteria for the  readiness of patients with cervical SC injury to transfer to spontaneous breathing, since they reflect not only the functional state of the diaphragm, but also the state of the lung tissue.