An Investigation of Diaphragm Function in Covid-19 Patients at a National Covid Referral Centre (KUTRRH)

Abstract

Background: Long COVID is a debilitating multisystem condition consisting of signs and symptoms that continue or develop after acute COVID-19 infection and are attributed to multiple overlapping mechanisms. The main symptoms of long covid in Africa include Fatigue (41%)confusion (40%) and dyspnea (25%).Dyspnea can result from diaphragm weakness due to the effects of Covid-19 on the diaphragm itself or the phrenic nerve that innervates it. The present study investigated the morphological and functional characteristics of the diaphragm in recovered mild Covid-19 patients. Objective: To investigate effect of Covid-19 on diaphragm function and morphology and contribution to long covid. Study setting: Kenyatta University Teaching Research and Referral Hospital (KUTRRH) Materials and methods: The study was performed on patients that had mild Covid-19 with positive PCR test and matched controls that did not have any Covid-19 like symptoms during the period of November 2021 to January 2022.A sample population of 80 participants was recruited using a convenience sampling method. All the subjects were evaluated by use of Phrenic nerve conduction studies (NCS) ultrasound and spirometry. The experimental data was statistically analyzed using unpaired student t test with significance level set at P< 0.05 using R software (version4.0.2) Results: The FEV1/FVC ratio was greater than 70% of the predicted value and the FEV1 was reduced in the Covid-19 patients. The diaphragm thickness was maintained. However, the amplitude and area under the curve of the compound muscle action potentials (CMAP) after phrenic nerve stimulation were reduced in the Covid-19 patients. Conclusion: Mild Covid-19 causes reduced amplitude and area of the CMAP suggesting axonal degeneration. This leads to diaphragm weakness, and reduced FEV1/FVC ratio resulting in restrictive pattern of lung disease and consequently contributing to long Covid respiratory dyspnoea