Hyperventilation can be a manifestation of anxiety that involves abnormally fast breathing (tachypnea) and an elevated minute ventilation that exceeds metabolic demand. This report describes a case of hyperventilation-induced hypocapnia resulting in tetany in a 16-year-old girl undergoing orthodontic extractions under intravenous conscious sedation. Pulse oximetry is the gold standard respiratoryrelated index in conscious sedation. Although the parameter has great utility in determining oxygen desaturation, it provides no additional information on respiratory function, including, for example, respiratory rate. In this case, we found capnography to be a very useful aid to monitor respiration in this patient and also to treat the hypocapnia.