Single breath anesthesia induction is a method used to induce general anesthesia through the administration of a high concentration of anesthetic gas in a single deep breath. This technique is designed for rapid and smooth induction in specific clinical scenarios, largely in pediatric patients and some adult cases where intravenous access is difficult or where rapid induction is necessary.
In single breath induction, the patient takes a single, deep inhalation of a potent anesthetic gas mixture—commonly sevoflurane—through a face mask. The goal is to deliver a high enough concentration of the anesthetic to induce unconsciousness with one breath. The alternative method of inhalational induction is to have the patient breathe normally from a titrated mixture of anesthetic gas and oxygen over multiple breaths.
During single breath anesthesia, the patient is seated or lying comfortably. Standard monitors such as a pulse oximeter, electrocardiogram, and blood pressure cuff are applied before beginning the induction. The anesthesiologist prepares the anesthesia machine by setting up a face mask connected to a circuit that delivers a mixture of oxygen or nitrous oxide and a volatile anesthetic, typically sevoflurane or, less commonly, desflurane. Before starting the induction, the patient is often preoxygenated with 100% oxygen for a few minutes. After preoxygenation, a face mask is placed securely over the patient’s mouth and nose, and the patient is asked to take a deep breath. Sevoflurane is commonly used because it has a low blood-gas partition coefficient, allowing for rapid uptake into the bloodstream and a fast onset of action. The patient then inhales deeply, filling their lungs with anesthetic gas. Anesthesia is typically achieved within one to two breaths, depending on the patient’s lung capacity and the concentration of the gas. Once the patient is unconscious, the anesthesia team adjusts the concentration of sevoflurane and switches to maintenance anesthesia at a lower concentration. The airway is secured, either with an endotracheal tube or a laryngeal mask airway, and the procedure continues as per the surgical plan 1.
The technique is designed to induce anesthesia quickly, which is advantageous in situations where speed is crucial, such as emergency surgeries or patients with difficult intravenous access. It avoids the need for intravenous access in the early stages, which is particularly beneficial in children or anxious adults who fear needles; many pediatric patients find it less stressful than intravenous induction. Furthermore, sevoflurane is associated with a low incidence of airway irritation and rapid recovery, making it ideal for induction 2,3.
Single breath anesthesia induction is a specialized technique with several benefits, particularly in pediatric and select adult populations. However, as with any anesthesia procedure, it requires careful patient selection and monitoring to ensure safety and effectiveness during its use.
References
1. Yurino, M. & Kimura, H. Single-breath induction of anesthesia: comparison of enflurane and sevoflurane. J. Anesth. 8, 178–181 (1994).
2. Hall, J. E., Stewart, J. I. M. & Harmer, M. Single-breath inhalation induction of sevoflurane anaesthesia with and without nitrous oxide: a feasibility study in adults and comparison with an intravenous bolus of propofol. Anaesthesia 52, 410–415 (1997). DOI: 10.1111/j.1365-2044.1997.091-az0086.x
3. Lejus, C. et al. Inhalation induction using sevoflurane in children: The single-breath vital capacity technique compared to the tidal volume technique. Anaesthesia (2006). doi:10.1111/j.1365-2044.2006.04661.x