CASE DESCRIPTION
A 72-year-old male was transferred from a local hospital on March 18, 2020, due to severe hypoxia and hypercapnia. The patient was taking medication for hypertension and dyslipidemia and was a nonsmoker. He developed upper respiratory symptoms such as headache, fever, chilling sensation, and cough 8 days before being transferred to our hospital. A real-time reverse transcriptase-polymerase chain reaction test for COVID-19 was done which confirmed COVID-19 infection 5 days prior to being transferred to our hospital. He was an inpatient at a local medical institution and was treated with antibiotics (levofloxacin) and antiviral agent (lopinavir/ritonavir) 2 days before being transferred to our hospital. However, the patient’s chest X-ray haziness was aggravated, fever was sustained, and hypoxia worsened despite the symptomatic treatment. His initial vital signs were blood pressure of 136/63 mmHg, heart rate of 79 beats/min, body temperature of 37.3℃, respiratory rate of 40 breaths/min, and peripheral O2 saturation of 90% on non-rebreather mask of 15 L/min. The pH, pO2, pCO2, and O2 saturation were 7.318, 78.1 mmHg, 50.7 mmHg, and 93.8%, respectively, in the arterial blood gas analysis. Chest X-ray demonstrated diffuse ground glass opacities in the left middle and both lower lobes (Fig. 1). Initial electrocardiogram (ECG) revealed normal sinus rhythm with a heart rate of 90 beats/min, normal PR (172 ms) and QRS (92 ms) intervals, and normal QT (350 ms) and QTc (428 ms) intervals (Fig. 2). The patient underwent intubation and was started on mechanical ventilator care 1 h after admission. Medical treatment was administered with antibiotics (levofloxacin) and antiviral agent (darunavir/cobicistat). A mechanical ventilator was applied, and midazolam and fentanyl citrate were used for sedation. The heart rate was stably maintained at 60–70 beats/min, and cardiac arrhythmia was not observed. On day 2 of hospitalization, antibiotics was changed from levofloxacin to piperacillin/tazobactam due to persistent fever. On day 4 of admission, the antiviral agent was stopped due to liver enzyme elevation. In addition, antibiotics (azithromycin) was added on day 6 of hospitalization because chest radiography demonstrated deteriorating pulmonary consolidation (Fig. 1). On day 9 of admission, a paroxysmal complete atrioventricular (AV) block was observed on the ECG monitor (Fig. 3). Paroxysmal complete AV block lasted for 5–10 s at the time of occurrence and developed one to two times per hour. Changes in consciousness, such as syncope, were not observed because the patient was in the sedation state at the time of paroxysmal complete AV block onset. Accordingly, we first identified and discontinued medication that could induced cardiac arrhythmia. The antibiotics piperacillin/tazobactam and azithromycin were discontinued and were changed to a different class of antibiotics. In addition, the mechanical ventilator setting value was adjusted in consideration of the possibility of AV block due to vagal overstimulation due to an increase in intrathoracic pressure and hyperinflation of the lungs. At the time, the patient’s mechanical ventilator was set to assisted/controlled mandatory ventilation – volume controlled ventilation mode with 340 ml per inspiration of tidal volume (TV), 10 cmH2O of positive end expiratory pressure (PEEP), 28 breaths/min of respiratory rate, and 50% fraction of inspiration oxygen.
TV and PEEP were adjusted from 340 to 320 ml per inspiration and from 10 to 8 cmH2O, respectively. Paroxysmal complete AV block did not occur 2 h after adjusting the mechanical ventilator, and follow-up ECG revealed normal sinus rhythm with a heart rate of 68 beats/min (Fig. 4). Thereafter, cardiac arrhythmia including paroxysmal complete AV block was not observed during the hospitalization period. Fortunately, the patient gradually recovered from acute respiratory distress syndrome. On day 13 of hospitalization, mechanical ventilation was stopped and extubation was performed. Finally, the patient was discharged 49 days after admission.