Isoflurane During Cardiopulmonary Bypass

Cardiopulmonary Bypass Clinical Trial

Official title:

The Depth of Anaesthesia Associated With the Use of 2.5% Isoflurane During Cardiopulmonary Bypass

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT02471950
• Other study ID #: 15 LO 0366
• Secondary ID: 2015/0199
• Status: Completed
• Start date: April 2015
• Est. completion date: January 2019

Study information

• Verified date: June 2021
• Source: University of Edinburgh
• Contact: n/a
• Is FDA regulated: No
• Study type: Observational

Clinical Trial Summary

There is no clinical way of assessing the depth of anaesthesia while patients are on the heart-lung machine. A new method of measuring the depth of anaesthesia using brainwaves called the Bispectral index (BIS) has been developed and its use in cardiac surgery is now widespread. However BIS is also altered by patients body temperature. As cooling is common during heart surgery the use of BIS to measure the depth of anaesthesia during heart-lung bypass remains controversial. This study aims to find out what depth of anaesthesia is produced according to BIS during heart lung bypass using a standard anaesthetic technique that utilises the anaesthetic isoflurane.

Description:

There is no clinical way of assessing patients' depth of anaesthesia on the heart-lung machine. For this reason, the amount of volatile anaesthetic agent like isoflurane, that is administered has traditionally been determined by anaesthetists' clinical experience. Recently, a device that assesses depth of anaesthesia by analysing the electrical brain waves called the Bispectral index (BIS) has been introduced. The study aims to determine whether the level of anaesthesia produced by isoflurane using the traditional approach is more than required simply to maintain unconsciousness according to BIS. In addition, the study will determine whether the concentration of isoflurane in exhaust gases from the heart-lung machine can be used as an estimate arterial blood concentration and so, depth of anaesthesia.

The study will recruit patients who are scheduled for heart surgery using a heart-lung machine. Patients will be anaesthetised using a long established balanced technique including the administration of isoflurane 2.5% whilst supported on the heart-lung machine. Measurements of exhaust gas concentration of isoflurane from the heart-lung machine and level of BIS will be recorded at three time points. Simultaneously, three arterial blood samples will be taken and the isoflurane concentration measured in these samples. The BIS levels will be averaged and the proportion of patients with a BIS below 40 (lower limit of normal) will be calculated. Concentrations of isoflurane in the exhaust gas of the heart-lung machine will be compared with blood concentrations of isoflurane and the both concentrations will be compared with the level of BIS to establish whether they can be used to assess depth of anaesthesia.

If this study finds that a large proportion of patients have more than adequate levels of anaesthesia, then future studies could explore whether administering lower concentrations of isoflurane improves outcome whilst maintaining anaesthesia.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 22
• Est. completion date: January 2019
• Est. primary completion date: January 2019
• Accepts healthy volunteers: No
• Gender: All
• Age group: 18 Years and older

Eligibility

Inclusion Criteria:

• Participants over the age of 18

• Scheduled for elective cardiac surgery under the care of trial anaesthetists

• Patient has provided informed consent to participate

Exclusion Criteria:

• Patients presenting for emergency cardiac surgery

• Patients who will have cardiac surgery that does not require cardiopulmonary bypass

• Unwilling/unable to provide informed consent

• Patients under the age of 18

• Anaesthesia undertaken by anaesthetists not involved in trial

Related Conditions & MeSH terms

• Cardiopulmonary Bypass
• Consciousness Monitors
• Isoflurane

Intervention

Procedure:
• 2.5 % Isoflurane administration
Anaesthesia maintained during cardiopulmonary bypass with 2.5% isoflurane administered via the oxygenator of the bypass circuit.

Locations

Country	Name	City	State
United Kingdom	Royal Infirmary of Edinburgh	Edinburgh	Scotland

Sponsors (1)

Lead Sponsor	Collaborator
University of Edinburgh

Country where clinical trial is conducted

United Kingdom, 

References & Publications (1)

Alston RP, Connelly M, MacKenzie C, Just G, Homer N. The depth of anaesthesia associated with the administration of isoflurane 2.5% during cardiopulmonary bypass. Perfusion. 2019 Jul;34(5):392-398. doi: 10.1177/0267659118822946. Epub 2019 Jan 12. — View Citation

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Depth of anesthesia according to BIS	BIS reading will be recorded at three time points during cardiopulmonary bypass	Intraoperative
Secondary	Comparison of exhaust gas and blood concentration of isoflurane	Exhaust gas and blood concentrations of isoflurane will be recorded at three time points during the operation. These values will be compared to see if their values are are related.	Intraoperative
Secondary	Comparison of blood isoflurane concentration and BIS score	Blood isoflurane concentration and BIS will be recorded at three time points and compared to see if they are related	Intraoperative
Secondary	Comparison of exhaust isoflurane Concentration and BIS score	Exhaust isoflurane and BIS will be recorded at three time points and compared to see they are related.	Intraoperative