LOW-FLOW ISOFLURANE-NITROUS OXIDE ANESTHESIA OFFERS SUBSTANTIAL ECONOMIC-ADVANTAGES OVER HIGH-FLOW AND MEDIUM FLOW ISOFLURANE-NITROUS OXIDEANESTHESIA

Isoflurane consumption was studied for three different fresh gas flows in patients scheduled for major elective abdominal, urological or gyn aecological surgery under general anaesthesia with an expected duratio n of 2 h or more. Thirty patients were randomly assigned to either hig h-flow anaesthesia using a partial rebreathing system without carbon d ioxide absorption (Mapleson D) or medium- or low-flow anaesthesia usin g a circle system with carbon dioxide absorption. Patients were anaest hetised with isoflurane in 40% oxygen and 60% nitrous oxide. The amoun t of isoflurane consumed was measured with a precision scale. The tota l consumption of liquid isoflurane (mean +/- s.d.) during the first 2 h was 40.8 +/- 12.2 ml in the high-flow group, 18.5 +/- 5.4 ml in the medium-flow group and 7.9 +/- 2.2 ml in the low-flow group. The corres ponding cost of isoflurane for the three groups was 214 Danish kroner (DKK) (19.5 Pound), 97 DKK (8.8 Pound) and 42 DKK (3.8 Pound), respect ively. The calculated total cost of anaesthetics was 286 DKK (26 Pound ), 155 DKK (14.1 Pound) and 91 DKK (8.3 Pound), respectively. In concl usion, low-flow isoflurane-nitrous oxide anaesthesia offers substantia l economic advantages over high- and medium-flow isoflurane-nitrous ox ide anaesthesia.