Around the globe, approximately 230 million surgeries involving general anesthesia occur each year (1). General anesthesia provides the analgesia and unconsciousness required for many surgical procedures. Several different agents can be used for induction (and maintenance) of anesthesia, and despite the ubiquity of general anesthesia in surgeries, anesthesiologists remain divided over the most ideal method of administration: inhalation/mask or intravenous induction? Although previously thought to be equivalent, inhalation and intravenous general anesthetics each demonstrate unique strengths and weaknesses.
First, inhalation or “volatile” anesthetics — including isoflurane, sevoflurane, desflurane, and nitrous oxide — are a popular choice in the operating room due to their relatively low cost (2-4). Administered through a face mask, tracheal tube, or laryngeal airway, inhalational agents have a rapid onset of action for anesthesia induction, but may provoke complications in pediatric and geriatric patients (4). Although children show less anxiety when anesthesia is induced via mask compared to intravenously, this form of anesthesia appears to be associated with a higher risk of perioperative respiratory distress, especially in patients with extant airway complications (5). Additionally, elderly patients who are maintained on inhalational anesthetics may be more prone to postoperative cognitive dysfunction (6). Finally, although controversial, some evidence points to a cardioprotective effect of inhalational anesthetics — studies show lower levels of cardiac troponin release, an indicator of myocardial damage, in cardiac surgery patients who received inhalational agents compared to those who received intravenous (7, 8).
Second, intravenous anesthetics — including propofol, the most common, followed by etomidate and thiopental — are considered the more expensive and labor-intensive options, but multiple studies have demonstrated advantages in postoperative outcomes. Compared to inhalational anesthetics, total intravenous anesthesia (TIVA) is associated with significantly fewer incidences of postoperative nausea and vomiting (PONV) (2, 4, 9, 10), with one study finding a relative risk reduction of nearly 40% (9). Evidence also suggests that satisfaction and self-reported recovery scores are higher in patients emerging from TIVA vs. inhalational anesthetics and even in patients induced intravenously then maintained with inhalational agents vs. full inhalation anesthesia (9-12). In contrast to inhalational anesthetics, however, intravenous anesthetics typically control only one function, such as loss of consciousness or analgesia, and cannot provide all aspects of general anesthesia, meaning multiple medications must be administered simultaneously to achieve the same effects as single-agent inhalational anesthetics, adding to the already elevated cost (13).
In summary, both inhalational and intravenous anesthetics exhibit risks and preventative factors that must be weighed when creating an anesthesia plan for individual patients. Researchers recommend considering the patient’s medical history, type of surgery, drug usage, fear of needles, airway quality, and personal preference (5, 14, 15). Indeed, according to a recent poll, 33% of adult patients preferred intravenous induction for anesthesia, while 50% opted for mask (15); meanwhile, mask induction prevails as the most common anesthesia induction method in pediatric surgery due to vein access issues and fear of propofol infusion syndrome (16). Moreover, although TIVA costs more, the cost of the antiemetic drugs frequently prescribed during emergence from inhalational anesthesia reduces the economic difference between the two methods (4). Both induction methods carry certain risks, but considering holistic perspectives can lead to the development of the safest and most effective regimen for each individual patient.
References
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