ChronoMAC is for the use of anaesthesiologists to assist in delivering appropriate doses of volatile anesthetic agents for patients of different ages. It allows calculation of the age adjusted Minimum Alveolar Concentation (MAC) of volatile anesthetic agents. Most volatile agent monitors are calibrated to an age of 40, and do not adjust for the different requirements at ages above and below this.

It is an iOS implementation of the nomograms published in "Age-related iso-MAC charts for Isoflurane, sevoflurane and desflurane in man" by Nickalls and Mapleson, in BJA 91(2) 170-4 (2003).

Given the patient’s age, end-tidal nitrous oxide concentration and chosen volatile agent, it allows calculation of the required end-tidal concentration of volatile agent to achieve a particular MAC adjusted for patient age. It also allows the reverse, that is calculation of the age adjusted MAC given the ET volatile concentration.

After entering
+ Patient age
+ Volatile agent used (sevoflurane, isoflurane or desflurane)
+ End-tidal nitrous oxide (%)


And either:
+ Desired MAC OR
+ End-tidal volatile concentration (%)


The other of these two that you do not enter will be calculated automatically.