MAAS Method (Minimal-flow Auto-control Anesthesia System) for the Administration of Desflurane and Sevoflurane

Summary

In the present work the investigators will study the accuracy of the MAAS (Minimal-flow Autocontrol Anesthesia System) method to estimate the percentage of halogenated anesthetic (HA) to be supplied to the anesthetic circuit based on the estimation of HA uptake during the maintenance phase. The investigators will evaluate the accuracy of sevoflurane and desflurane vaporizers to guarantee the administration of that amount of estimated HA, thus guaranteeing the maintenance of the target concentration of HA at the end of expiration: end-tidal target HA% (ettHA%). To do this, the investigators will quantify the number of adjustments that need to be made to each vaporizer to maintain ettHA%. As secondary objectives, the investigators will analyze the time to reach the target concentration of HA, the deviations that occur from that concentration despite the correct application of the method, and the consumption of HA during the procedure.

Through the entire procedure, all participants will be ventilated under a tailored open lung approach (tOLA) strategy.

Conditions

• Anesthesia
• Sevoflurane
• Desflurane
• Low Flow Anesthesia

Interventions

PROCEDURE

Sevoflurane uptake and supply

Phase sevo 1) * Moment 1 (M1): from OTI until end-tidal sevoflurane (etSEVO%) exceeds ettSEVO% by 10%. Deliver of sevoflurane to the system (SEVOdel) carried out by completely opening sevoflurane vaporizer (8%). * M2) once etSEVO% surpass ettSEVO% by 10%: turn off sevoflurane vaporizer and observe the progressive fall etSEVO%. When etSEVO% approaches ettSEVO% (0.1-0.2 points above ettSEVO%), the investigators will turn on the sevoflurane vaporizer following the MAAS method to ensure stability in inspired and expired concentrations of sevoflurane. Phase sevo 2) Objective: to maintain etSEVO% = ettSEVO% ±5% When the etSEVO% increases above the mentioned levels \>\> reduce SEVOdel by 0.25-0.5%. When the etSEVO% decreases below the mentioned levels\>\> increase SEVOdel by 0.25-0.5%.

PROCEDURE

Washout phase

The investigators will close the sevoflurane vaporizer and will start the administration of Propofol in intravenous perfusion; the investigators will then open the FGF sequentially at 2\>5\>10 liters per minute (LPM), until the etSEVO% is \<0.2 MAC.

PROCEDURE

Desflurane uptake and supply

Phase desflu 1) * Moment 1 (M1): from the end of Washout phase until end-tidal desflurane (etDESFLU%) exceeds ettDESFLU% by 10%. Deliver of desflurane to the system (DESFLUdel) carried out by completely opening the desflurane vaporizer (18%). * M2) once etDESFLU% surpass ettDESFLU% by 20%: turn off the desflurane vaporizer and observe the progressive fall etDESFLU%. When etDESFLU% approaches ettDESFLU% (0.8-1.2 points above ettDESFLU%), the investigators will turn on the desflurane vaporizer following the MAAS method to ensure stability in inspired and expired concentrations of desflurane. Phase desflu 2) Objective: to maintain etDESFLU% = ettDESFLU% ±5% When the etDESFLU% increases above the mentioned levels \>\> reduce DESFLUdel by 0.25-0.5%. When the etDESFLU% decreases below the mentioned levels\>\> increase DESFLUdel by 0.25-0.5%.

PROCEDURE

Final phase

From the end of Phase desflu 2 until the end of the intervention. Maintenance of anesthesia with desflurane following the principles of MAAS Method. Between 15-20 minutes before the end of the intervention, the investigators will stop the administration of desflurane, registering the time until the reaching etDESFLU% \< 0.2 MAC.

Sponsors & Collaborators

• Fundación Pública Andaluza para la gestión de la Investigación en Sevilla

  lead OTHER

Principal Investigators

• Manuel de la Matta, PhD · Hospitales Universitarios Virgen del Rocío

Study Design

Allocation

NA

Purpose

TREATMENT

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

18 Years

Max Age

99 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2024-04-03

Primary Completion

2025-06-30

Completion

2025-06-30

Countries

• Spain

Study Locations