Cardiovascular collapse during transcatheter aortic valve replacement in monitored anesthesia care using an end-tidal carbon dioxide monitor: a case report

Abstract

Capnography is commonly used to monitor respiration during general anesthesia. However, it has limited utility in patients with respiratory distress during sedation. This case report examines capnography use in a transcatheter aortic valve replacement procedure performed on an elderly woman with severe aortic stenosis. A 73-year-old woman with a history of non-ST-elevation myocardial infarction and congenital heart failure presented with severe dyspnea caused by severe aortic stenosis. Transcatheter aortic valve replacement was preferred over surgery due to her comorbidities. Monitored anesthesia care was administered with a capnogram. During the procedure, the patient was sedated with remimazolam, maintaining a bispectral index range of 60–80 and a score of 2 on the Modified Observer’s Assessment of Alertness/Sedation scale. Although irregular breathing patterns and a gradual decrease in oxygen saturation were observed following remimazolam infusion, the patient’s respiration eventually stabilized. However, the patient experienced cardiovascular collapse 45 minutes after sedation began. The arterial carbon dioxide pressure measured by arterial blood gas analysis performed just before resuscitation was 68.4 mmHg. After one cycle of resuscitation, the patient recovered. The procedure was successfully performed under general anesthesia, which was replaced with monitored anesthesia care during resuscitation. Although most monitoring devices have similar utility for both general anesthesia and sedation, capnography has limitations for evaluating respiration during sedation, especially for patients with respiratory distress. Therefore, anesthesiologists or medical staff who provide sedation should not neglect periodical arterial carbon dioxide pressure observations via other methods, such as arterial blood gas analysis.