Closed Loop Isoflurane Administration With Bispectral Index in Open Heart Surgery

Summary

With the advancement in microprocessor technology and better understanding of pharmacodynamics and pharmacokinetics of anaesthetic agents, computer facilitated closed loop control of anaesthesia using propofol has been shown to be accurate with better performance than manual control. Literature on computer controlled administration of inhalational anaesthetics is few, as it requires the computer to control the dial setting on the vapouriser. The investigators intend to compare the computer controlled closed loop administration of isoflurane by infusing it into the anaesthetic circuit with conventional vaporiser control in elective open heart surgery.

40 patients (ASA (American Society of Anesthesiology) class II-IV; 18- 65 years) undergoing elective cardiac surgery requiring cardiopulmonary bypass (CPB) will be randomly divided into manual or closed loop groups. Propofol will be used for induction of anaesthesia in both groups followed by isoflurane for maintenance. In the manual group, isoflurane will be administered through the Tech 7 vapouriser during pre and post CPB periods to target bispectral index (BIS) of 50. In closed loop group, isoflurane will be administered using infusion of liquid isoflurane into expiratory limb of the closed circuit. This rate of infusion though a conventional syringe pump will be controlled by algorithm termed 'Improvised Anaesthetic Agent Delivery System' (IAADS) to maintain BIS of 50. Patients in both groups will receive 500ml of 100 % oxygen as fresh gas flow. The % of time bispectral index (BIS) is within the 10 of set target BIS of 50 will be the primary outcome measure. The secondary outcome measures will be median performance error (MDPE)(2), median absolute performance error (MDAPE)(2), wobble(2), divergence(2), amount of isoflurane used and hemodynamic parameters will be secondary outcome measures.

Conditions

• Open Heart Surgery

Interventions

OTHER

Conventional control

The isoflurane administration to deliver anesthesia will be done conventionally through a Tec 7 vaporiser to maintain the bispectral index at 50.

OTHER

Closed loop control

The isoflurane administration to maintain anesthesia will be by infusion to the anesthesia circuit using syringe pump (injection technique). The rate of delivery of isoflurane will be regulated by computer that uses a control algorithm.

Sponsors & Collaborators

• Post Graduate Institute of Medical Education and Research, Chandigarh

  lead OTHER

Principal Investigators

• Puri GD, MBBS MD PhD · Post Graduate Institute of Medical Education and Research, Chandigarh

• Sethu Madhavan, MBBS · Post Graduate Institute of Medical Education and Research, Chandigarh

• Preethy J Mathew, MBBS, MD · Post Graduate Institute of Medical Education and Research, Chandigarh

Study Design

Allocation

RANDOMIZED

Masking

SINGLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

65 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2009-01-31

Primary Completion

2010-06-30

Completion

2010-06-30

Countries

• India

Study Locations