Blood Propofol Concentrations in Children During Spinal Surgery

NHS Foundation Trust

Status and phase: Completed; Phase 4

Conditions: Idiopathic Scoliosis; Spine Deformities; Neuromuscular Dystrophy

Treatments: Device: Pelorus 1500; Drug: Propofol 2% (Diprivan 2%, Astra Zeneca UK)

Study type: Interventional

Funder types: Other

Identifiers

NCT01932424

12AR04

Details and patient eligibility

About

During major spinal surgery evoked potential monitoring is performed to detect spinal cord damage. Intra-venous anaesthesia is the preferred anaesthetic technique because volatile anaesthetic agents supress the evoked potentials. Total Intra-Venous Anaesthesia (TIVA) with propofol is commonly administered as a Target Controlled Infusion (TCI). The TCI is an automated drug delivery system which administers propofol to achieve a desired blood concentration, based on an in built pharmaco-kinetic data (TCI model) derived from previous studies. The TCI model also provides a real time predicted blood concentration to facilitate the anaesthetist to adjust the target concentration of propofol.

The TCI algorithm is based on pharmaco-kinetic data derived from previous studies in a relatively small number of patients, by a "best fit" relationship between blood levels, infusion rates and other factors (such as age and weight). Several factors make it possible for a wide discrepancy between the predicted and the true blood concentrations. This difference can be higher in children compared to adults. Also blood loss and administration of large volumes of intravenous fluids can affect the blood concentrations. This study aims to identify the difference between the predicted and true blood concentrations by using Pelorus 1500, a bedside blood propofol measurement device, in children undergoing major spinal surgery under TIVA.

Enrollment: 20 patients

Sex: All

Ages: 5 to 18 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Children undergoing major spinal surgery under propofol TCI
• Surgery expecting to last more than 3 hours.

Exclusion criteria

• Major hepatic or renal disease

Trial design

20 participants in 1 patient group

Single arm

Experimental group

Description:

The intervention in this study involves taking blood sample from an existing arterial line for measurement of blood propofol levels. The drug in evaluation is Propofol 2% (Diprivan 2%, Astra Zeneca UK) administered as a target controlled infusion using the commercially available paediatric TCI models (Paedfusor and Marsh models). The dose range is usually between a target concentration of 3-8 mcg/ml. However the anaesthetic management is not changed for the study. The blood concentrations of propofol will be measured using Pelorus 1500 (Sphere Medical, UK), a CE marked device. The anaesthetist will be blinded from the measurements, unless the measured value was outside the safe limit ( \< 3 mcg/ml or \> 10mcg/ml).

Treatment:

Drug: Propofol 2% (Diprivan 2%, Astra Zeneca UK)

Device: Pelorus 1500