Implications of Inspired Carbon Dioxide During Ophthalmic Surgery Performed Using Monitored Anesthesia Care

Inspired concentration of carbon dioxide (FICO₂) in ophthalmic surgery performed under monitored anesthesia care (MAC) has been largely ignored in the recommended monitoring standards of professional anesthesia societies. Most ophthalmic procedures are performed using MAC with facial draping that has been shown to retain carbon dioxide in the ambient air surrounding the patient. The administration of supplemental oxygen has been shown to prevent hypoxia but not hypercapnia. Hypercapnia can lead to physiologic changes, including tachypnea, tachycardia, and increased intraocular pressure. Several closed-claim analyses have described adverse outcomes related to ventilation and oxygenation of patients during MAC. A literature search using the keywords of ophthalmic surgery, monitored anesthesia care, and inspired carbon dioxide was conducted, and relevant articles dealing with possible complications, methods of measurement, and abatement strategies were examined. No procedure has gained widespread acceptance, yet practitioners employ a variety of methods to decrease FICO₂, a parameter not mentioned in the anesthetic record although it is measured by current anesthesia workstations. The goal of this review is to encourage investigation of this underreported parameter.