Author: Franklin Dexter, et al.
Cureus, June 22, 2026
Prolonged tracheal extubation, defined as 15 minutes or longer from the end of surgery until removal of the endotracheal tube, reduces operating room efficiency and leaves the surgical team idle. Residual volatile anesthetic at the end of surgery is a major modifiable cause of delayed extubation.
Because minimum alveolar concentration decreases with age, the same end-tidal concentration represents a greater anesthetic dose in an older patient than in a younger patient. Modern anesthesia machines can display the age-adjusted MAC fraction in real time, potentially helping clinicians avoid excessive volatile anesthetic administration in older adults.
This retrospective cohort study evaluated whether patient age remained associated with anesthetic dosing and prolonged extubation when anesthesia workstations displayed age-adjusted MAC fractions.
Methods
The investigators analyzed 75,050 general anesthesia cases performed at the University of Iowa.
Included patients:
• Were older than 30 years
• Received general anesthesia with tracheal intubation
• Had a mean MAC fraction greater than 0.6 during the procedure
• Were managed using anesthesia machines that displayed age-adjusted MAC fractions
The investigators examined the relationships between:
• Patient age and average MAC fraction during anesthesia
• Patient age and MAC fraction at the end of surgery
• Patient age and prolonged tracheal extubation
Key findings
There was a statistically significant association between age and the average MAC fraction during surgery, but the magnitude was extremely small.
The Spearman correlation was only 0.021, indicating that age had almost no clinically meaningful effect on anesthetic dosing when clinicians could see the age-adjusted MAC fraction.
This correlation was substantially lower than the previously reported correlation of 0.12 at an institution where anesthesia machines did not display MAC fractions.
There was no significant association between patient age and the MAC fraction remaining at the end of surgery.
There was also no significant association between age and prolonged extubation. The area under the receiver operating characteristic curve was 0.503, which is essentially no better than chance for predicting prolonged extubation based on age.
Clinical implications
Real-time display of age-adjusted MAC fractions appears to minimize age-related dosing differences during volatile anesthesia.
When clinicians were shown the appropriate age-adjusted MAC fraction:
• Older patients were not left with greater residual anesthetic concentrations at the end of surgery.
• Older age did not increase the likelihood of prolonged tracheal extubation.
• Delayed extubation appeared to be more closely related to clinician anesthetic-titration behavior than to patient age.
The findings reinforce the importance of reducing volatile anesthetic concentrations early enough before the anticipated end of surgery. Simply recognizing that a patient is elderly is less useful than continuously monitoring and appropriately responding to the displayed age-adjusted MAC fraction.
Operating room implications
Extubation delays are economically important because surgeons, nurses, anesthesia personnel, and operating room resources remain occupied without progressing to the next case.
Anesthesia departments may improve operating room efficiency by:
• Ensuring that anesthesia machines display age-adjusted MAC fractions
• Educating clinicians to titrate volatile agents according to the displayed fraction
• Establishing expectations for reducing anesthetic concentrations before surgery ends
• Monitoring prolonged extubation rates as a clinician-level quality measure
• Providing feedback when residual volatile anesthetic repeatedly contributes to delayed emergence
Important limitations
This was a retrospective study from a single academic institution, so the findings may not apply to all hospitals or anesthesia practices.
The study demonstrated associations but could not prove that displaying MAC fractions directly caused the elimination of age-related extubation differences.
The analysis focused on inhalational anesthesia and did not address delayed emergence caused by opioids, benzodiazepines, neuromuscular blockade, metabolic abnormalities, neurologic events, or total intravenous anesthesia.
The cohort also excluded patients with an average MAC fraction of 0.6 or less, which may limit the applicability of the findings to lower-dose or highly opioid-based anesthetic techniques.
Bottom line
When anesthesia machines displayed real-time age-adjusted MAC fractions, patient age had virtually no clinically meaningful effect on volatile anesthetic dosing, residual anesthetic concentration at the end of surgery, or the incidence of prolonged tracheal extubation.
The findings suggest that delayed extubation during inhalational anesthesia is primarily related to clinician titration and timing rather than the patient’s age.
Age-adjusted MAC displays provide clinicians with actionable information that may reduce excessive anesthetic dosing in older patients and improve operating room efficiency.
Thank you to Cureus for allowing us to summarize this article.