<prompt> MAC stands for?Minimum alveolar concentrationMinimal analgesic concentrationMinimal anesthetic concentrationMaximum alveolar concentration  <response>: Ans. is a i.e., Minimum alveolar concentration Minimal alveolar concentration MAC Most important measure of potency is minimal alveolar concentration MAC. MAC is the lowest concentration of the anesthetic in pulmonary alveoli needed to produce immobility in response to a painful stimulus surgical incision in 50 individuals. Higher the MAC, less potent the anesthetic agent. Methoxyflurane has minimum MAC 0.16 - The most potent inhalational agent. N2O has maximum MAC 105 - The least potent inhalational agent. Order of potency in decreasing order MAC in increasing order: - Methoxyflurane MAC 0.16 Trilene MAC 0.2 Halothane MAC 0.74 Chloroform MAC 0.8 Isoflurane MAC 1.15 Enflurane MAC 1.68 Ether MAC 1.92 Sevoflurane MAC 2.0 Desflurane MAC 6.0 Cyclopropane MAC 9.2 N20 MAC 104.Factor affecting MAC1. Age: - Young age increases and old age decreases MAC.2. Alcohol: - Chronic intoxication increases and acute intoxication decreases MAC.3. Temperature: - Both hypothermia and hyperthermia decrease MAC.4. Electrolyte: - Hypercalcemia, Hypermagnesemia Hyponatremia decrease. Whereas hypernatremia increases MAC.5. Anemia : - Decrease MAC6. Hypoxia pO2 40, and hypercarbia pCO2 95 decrease MAC.7. Pregnancy: - Decreases MAC8. Drugs: -A. Decreasing MAC - Local anaesthetics except cocaine Opioids, Ketamine, Barbiturates, Benzodiazepines, Verapamil, Lithium, Sympatholytics Methyldopa, reserpine, Clonidine, Dexmedetomidine, Chronic amphetamine use.B. Increasing MAC: - Acute amphetamine intake, Cocaine, ephedrine. 