Perioperative Management of Interscalene Block in Patients with Lung Disease

Interscalene nerve block impairs ipsilateral lung function and is relatively contraindicated for patients with lung impairment. We present a case of an 89-year-old female smoker with prior left lung lower lobectomy and mild to moderate lung disease who presented for right shoulder arthroplasty and insisted on regional anesthesia. The patient received a multimodal perioperative regimen that consisted of a continuous interscalene block, acetaminophen, ketorolac, and opioids. Surgery proceeded uneventfully and postoperative analgesia was excellent. Pulmonary physiology and management of these patients will be discussed. A risk/benefit discussion should occur with patients having impaired lung function before performance of interscalene blocks. In this particular patient with mild to moderate disease, analgesia was well managed through a multimodal approach including a continuous interscalene block, and close monitoring of respiratory status took place throughout the perioperative period, leading to a successful outcome. 1. Introduction Impaired lung function has traditionally been considered a relative contraindication to interscalene plexus block (ISB). ISB has been shown to cause ipsilateral hemidiaphragmatic paresis virtually 100% of the time [1, 2] with significant decreases in several pulmonary measurements [1]. Knowledge of the potential complications is critical, even if they occur rarely. At the same time, opioids impair respiratory function and should be minimized if lung function is tenuous [3]. The elderly in particular are sensitive to the depressant effects of anesthetics and medications that cause muscle weakness [4], especially opioids. Excellent postoperative analgesia, therefore, is a key component in the prevention of postoperative pulmonary complications in this population. 2. Case Description The patient was an 89-year-old woman, American Society of Anesthesiologists Physical Status 3, with hypertension, hypothyroidism, and a 58-pack-year history of smoking who five years prior had undergone a left lung lower lobectomy for cancer. She was scheduled to undergo a right total shoulder replacement for worsening degenerative disease and pain. Pulmonary function testing performed 17 months prior to surgery revealed a FEV1/FVC ratio of 0.68, indicating mild obstructive disease, and a diffusion capacity (DLCO) of 9.5？mL/mm？Hg/min, indicating a moderate gas transfer defect. Physical examination revealed clear lung fields bilaterally and a short hyomental distance on airway exam. Preoperative pulse oximetry on room air revealed an oxygen