A Comparative Study on Minimal Flow Anaesthesia in Geriatric and Middle-aged Patients.

Abstract

Objective: Minimal flow anaesthesia reduces costs and environmental pollution, and has a protective effect on the respiratory tract. This study aimed to compare the ease and tolerability of minimal flow anaesthesia in the geriatric and middle-aged patient populations.

Methods: In this prospective study, we enrolled 40 patients between 18 and 50 years (Group Y) and 40 patients 65 years or older (Group E), scheduled for abdominal surgery under general anaesthesia. Following a period of high flow with desflurane in O₂/air, the fresh gas flow was reduced to 350 mL min^-1. Desflurane concentration was adjusted to maintain a bispectral index between 40 and 50. The oxygen concentration in fresh gas flow was titrated by ±10%. Throughout the surgery, gas concentrations, oxygenation parameters, hemodynamic data, and the depth of anaesthesia were monitored. The number of alterations in fresh gas oxygen and desflurane concentrations was recorded.

Results: The depth of anaesthesia and oxygenation parameters were adequately sustained within safe limits among all patients, while the number of changes in the fresh gas flow oxygen levels was found to be significantly lower in geriatric patients. The increase in the number of oxygen level was 1.1±0.8 in Group E and 1.8±1.2 in Group Y (P=0.006). Total alteration in oxygen was 1.2±1 in Group E and 1.9±1.3 in Group Y (P=0.01). Oxygenation parameters consistently remained within clinically acceptable ranges in both groups, and the amount of change in desflurane concentration showed no intergroup difference.

Conclusion: Administering minimal flow anaesthesia at a rate of 350 mL min^-1 in the geriatric population, compared to the younger population, can be performed requiring less manipulation, without inducing hypoxia or inadvertent awareness.