Hensley's Practical Approach to Cardiothoracic Anesthesia

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26. Anesthetic Management for Interventional Pulmonology Procedures

I. Introduction Interventional pulmonology (IP) is a subspecialty of pulmonary medicine focused on using mini mally invasive diagnostic and therapeutic techniques in patients with lung, mediastinal, pleural, and complex airway diseases. A. Indications: Referral to an IP specialist is prioritized for the diagnosis and treatment of a variety of chest-related disorders. In recent years, as the minimally invasive techniques of IP procedures have advanced, patients who would have previously required more invasive tho racic surgical or interventional radiology (IR) approaches are now increasingly referred to un dergo IP procedures instead. Due to the endoscopic nature of the procedures, patients can recover and be discharged faster than if they had undergone an open diagnostic or therapeutic intervention. B. Alternatives: Not all pulmonary disease processes are amenable to IP therapies or accessible with IP diagnostic technologies. Alternatives to IP procedures include computed tomography (CT)-guided percutaneous biopsy, as would be performed by IR specialists, or video-assisted thoracic surgery (VATS) biopsy, performed by a thoracic surgeon. Both CT-guided and VATS biopsies have a high diagnostic yield but are limited to one side at a time. In addition, CT-guided procedures for mediastinal lymphadenopathy staging are associated with a higher risk of complications. The higher yield of CT-guided percutaneous biopsy, as compared to IP advanced bronchoscopy, is related to the quality of the preprocedural CT, navigational ability, and real-time confirmation. 1 II. Anesthetic Approaches A. Local: Airway Topicalization 1. Anatomy: Key structures requiring topicalization include the nasopharynx, posterior oropharynx including tonsillar pillars, vocal cords, and the trachea. Topical anesthesia to these areas will cover sensory innervation, including the pharyngeal branch of the maxillary nerve (nasopharynx), the glossopharyngeal nerve (oropharynx), the internal laryngeal branch of the superior laryngeal nerve (larynx above the vocal cords), and the recurrent laryngeal nerve (trachea below the vocal cords). Inadequate topicalization increases the risk of cough and laryngospasm during instrumentation of the pharynx and larynx. 2. Methods for topicalizing: Commonly used techniques include nebulization of 4% lido caine; spraying of 4% lidocaine with the McKenzie technique or a mucosal atomizer; appli cation of 4% lidocaine ointment or solution on cotton swabs, gauze, or nasal trumpets; and nerve blocks of the glossopharyngeal, superior laryngeal, and recurrent laryngeal nerves. Relevant anatomy is shown in Figure 26.1. The use of one technique does not preclude the others, and frequently more than one method of topicalization is employed. Lidocaine spray has been shown to be more effective than nebulized lidocaine. 2 Cricothyroid lido caine administration has been shown to result in less cough and superior operator-rated procedural satisfaction, at a lower cumulative lidocaine dose, when compared to spray-as you-go lidocaine administration. 3 3. Toxicity: While systemic absorption of topically administered local anesthetic is lower than expected, there is always the possibility of toxicity with excessive administration. Met hemoglobinemia can develop with benzocaine, although other local anesthetics have also been described as causal; this is characterized by hypoxemia and cyanosis, which can be fa tal if untreated. Treatment is with intravenous methylene blue. In addition, local anesthetic systemic toxicity (LAST) has been reported and is characterized first by tinnitus or perioral tingling, escalating to seizure and ultimately cardiac arrest. Treatment is with intravenous lipid emulsion therapy and supportive care.

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CLINICAL PEARL Lidocaine nebulization is the most common modality for airway topicalization.