HP36: Diaphragm impairment in patients with COVID-19: A case-control study

Objective: Physicians have observed ventilation disorders in patients with COVID-19. The possible impairment of the diaphragm could be related to the systemic inflammatory response that typifies this infection. We aimed to assess the diaphragmatic function in patients with severe COVID-19. Methods: We recruited patients admitted with pneumonia and positive PCR for SARS-CoV-2, differentiating two groups according to their respiratory symptoms. The cases group consisted of 9 inpatients with moderate-severe dyspnea, pain with diaphragmatic origin or hiccup. The control group consisted of 10 inpatients who suffered from mild dyspnea. We performed phrenic nerve electroneurogram and diaphragmatic ultrasound to assess the diaphragmatic function. Results: We observed differences in the amplitude of evoked potentials, being 25.92% (SEM:7.22) in the cases group vs 19.81% (SEM:5.27) in the control group (p = 0.711). The right diaphragm thickness mean was 46.67% (SEM:8.86) in the cases group vs 62.15% (SEM:5.58) in the control group (p = 0.432), the left diaphragm thickness mean was 57.89% (SEM:15.36) in the cases group vs 73.34% (SEM:6.74) in the control group (p = 0.730), the right expiratory fraction mean was 0.53 (SEM:0.11) in the cases group vs 0.59 (SEM:0.05) in the control group (p = 0.674), and the left expiratory fraction mean was 0.58 (SEM:0.15) in the cases group vs 0.73 (SEM:0.07) in the control group (p = 0.195). Conclusion: Although diaphragmatic dysfunction is difficult to detect, our combined functional and morphological approach with electroneurograms and ultrasounds could improve diagnostic sensitivity. We suggest that diaphragmatic dysfunction could play a relevant role in respiratory failure in patients with COVID-19.