Evaluation of using distal part of endotracheal tube samples for SARS-COV-2 diagnosis by RT-PCR

Abstract

Objective: The reverse transcription-polymerase chain reaction (RT-PCR) analyses method is the most important diagnostic method in the diagnosis of SARS-CoV-2 virus infection. In this research, we  aimed to investigate the positivity of SARS-CoV-2 by RT-PCR from distal part of the endotracheal tube (DPET) samples, which have not been investigated in any study yet.

Materials and Methods: A total of 48 patients with a diagnosis of COVID-19 hospitalized in the intensive care unit receiving mechanical ventilation and whose conditions resulted in death or extubation were included in the study. The distal 6 cm part of the orotracheal intubation tube was removed from the patient (including the cuff). DPET samples were mixed with viral transport medium and vortexed; then, it was centrifuged at 4500g for 4 minutes. RNA isolation was performed by taking 400 µl from the supernatant and then SARS-CoV-2 RT-PCR was studied.

Results: In 15 patients (31.25 %) the swab samples were PCR positive, 42 patients (87.5 %) had positive computed tomography finding and 48 patients (100 %) had positive clinical findings. Among the patients whose oropharynx (OP)/nasopharynx (NP) combined swab sample was positive for RT-PCR, the rate of RT-PCR positivity detected in DPET samples was 26.7%. While OP/NP combined swab sample was negative, DPET RT-PCR positivity rate was found to be 9.09%.

Conclusions: Patients with positive DPET RT-PCR are detected when the swab is negative. These findings suggest that DPET can be used as a good lower respiratory sample without the risk of particle spread and transmission to healthcare personnel.