Amlodipine and Atropine for Hypoxia During One-Lung Ventilation: A Case Report

Abstract

Anesthetists are concerned about the causes and management of hypoxia during one-lung ventilation (OLV). Here, we report a hypoxic case during OLV and video-assisted thoracic surgery (VATS) for pulmonary lobectomy. The preoperative management of hypertension with amlodipine was considered to be responsible for the hypoxia. As a calcium channel blocker, amlodipine may inhibit hypoxic pulmonary vasoconstriction (HPV) and contribute to the reduction of the ventilation/perfusion ratio (or V/Q ratio). The hypoxia efficiently was treated by atropine, where both tracheal effects and the enhancement of HPV through muscarinic receptor blocking may work. For patients undertaking OLV, the effects of calcium channel blockers as a potential cause for hypoxemia should be paid attention to, where atropine administration may be of clinical benefit. One-lung ventilation (OLV) generally is used during anesthesia for thoracic surgeries. For OLV, a double-lumen tracheal tube (DLT) is used to realize lung separation in the airway. This technique is essential because it facilitates the surgical performance as well as isolates a healthy lung from the pathologic one. However, there are some concerns for OLV during anesthesia, where hypoxemia is commonly seen. There are many causes for hypoxemia during OLV. These include, for example, reduced oxygen stores due to the collapse of the non-ventilation lung, ventilation-perfusion mismatch induced by both lateral positions, and decrease in elastic recoil leading to more atelectasis. Accordingly, management of hypoxemia during OLV generally have been applied. Increase fraction of inspiration O2 (Fi O2) to 1, double checking the position of DLT, applying positive end expiratory pressure (PEEP), optimizing cardiac output (CO) all have been proven to be effective. Here, we report an efficiently treated hypoxemia case using atropine during video-assisted thoracic surgery (VATS) for pulmonary lobectomy. Preoperative medication of amlodipine may contribute to the hypoxemia through attenuating HPV during OLV, which may be antagonized by possible HPV augmentation of atropine. Further investigation is therefore suggested.