Influence of the inflated cuff balloon of a laryngeal tube on carotid artery blood flow

ISRCTN ISRCTN18341153
DOI https://doi.org/10.1186/ISRCTN18341153
Secondary identifying numbers 3
Submission date
02/07/2017
Registration date
19/07/2017
Last edited
21/02/2018
Recruitment status
No longer recruiting
Overall study status
Completed
Condition category
Other
Prospectively registered
Protocol
Statistical analysis plan
Results
Individual participant data
Record updated in last year

Plain English summary of protocol

Background and study aims
Endotracheal intubation is a medical procedure in which a tube is placed into the windpipe (trachea) through the mouth or nose. It is accepted as the “gold standard” to maintain an open airway. However, the laryngeal tube (LT) is an alternative technique that is gaining more importance in the daily clinical routine of emergency and intensive care medicine. The advantage of this new airway device is that it can be inserted blindly through the oropharynx (throat) which enables emergency care personnel to secure a patients’ airway even if they are not in regular use of endotracheal intubation. The LT has been successfully tested in several clinical situations. Little is known about the effects of using the LT on the heart and blood vessels. One study measuring carotid artery blood flow in pigs suggests that there is decreased blood flow when an airway device including the LT is used. For the LT, this might be caused by the extensive volume of the cuff balloon decreasing blood flow in the carotid arteries. The aim of this study is to assess the effects of the different airway devices on carotid artery blood flow during general anaesthesia for routine surgery.

Who can participate?
Healthy patients aged 18 or over scheduled for any kind of surgery

What does the study involve?
Participants are randomly allocated to either the endotracheal tube (ET) or laryngeal tube (LT) group. Once the participants have been anesthetized the allocated airway device is used. After securing the airway an ultrasound examination of carotid artery blood flow is carried out. After this has been done, the participant is intubated using the other airway device. After re-intubation, the ultrasound examination is repeated. These measurements are then used to compare the LT with the ET.

What are the possible benefits and risks of participating?
There are no expected benefits for the participants. Participating might result in a slightly increased risk due to one additional intubation procedure.

Where is the study run from?
University Hospital Krems, Karl Landsteiner University of Health Sciences (Austria)

When is the study starting and how long is it expected to run for?
July 2017 to December 2018

Who is funding the study?
Karl Landsteiner University of Health Sciences (Austria)

Who is the main contact?
Dr Raphael van Tulder
raphael.van-tulder@meduniwien.ac.at

Contact information

Dr Raphael van Tulder
Scientific

Mitterweg 10
Krems
3500
Austria

ORCiD logoORCID ID 0000-0002-0929-8988
Phone +43 (0)273 290 044 610
Email raphael.van-tulder@meduniwien.ac.at

Study information

Study designProspectively randomized controlled cross over study
Primary study designInterventional
Secondary study designRandomised cross over trial
Study setting(s)Hospital
Study typeNot Specified
Participant information sheet Not available in web format, please use the contact details to request a patient information sheet
Scientific titleThe influence of the inflated cuff balloon of the laryngeal tube compared to the endotracheal tube on carotid artery blood flow in anaesthetized patients: a randomized cross over study
Study acronymLT-CBF-Study
Study objectivesThere is a difference in the peak systolic velocity (measured with carotid ultrasound) in the carotid artery comparing the laryngeal tube versus the endotracheal tube.
Ethics approval(s)The ethics committee of Lower Austria, 06/07/2017
Health condition(s) or problem(s) studiedEmergency medicine, anesthesiology
InterventionAdult patients scheduled for elective surgery for any reason will be asked to take part in this study. Informed consent will be obtained after intensive education and during regular pre-anaesthesiological education before surgery. In advance of the study all patients will receive a standard carotid ultrasound. The extracranial carotid arteries will be carefully scanned by duplex ultrasound to exclude >25% stenosis, dissections or aneurysms. After ruling out carotid pathologies regular pre-surgery evaluation will be performed according to local standards.

A non-involved statistician will perform 1:1 randomization before the study starts. Concealment will be achieved with sequentially numbered, opaque and sealed envelopes. At the time the patient is brought to the operational room, a member of the study team will open the dedicated envelope. The patient will then be randomized to either the primary endotracheal tube (ET) or laryngeal tube (LT) group. For airway management procedures regular ETs sized 7.5 mm I.D. for female patients and 8.5 mm I.D. for male patients, as well as LTs sized 4 for all patients (of 155-180 cm height) will be used. Both airway devices are CE marked and in regular use for securing the airway under several circumstances.

During the pre-surgery preparation every patient will be monitored with a standard anaesthesia/operational room setting containing peripheral oxygen saturation (SpO2), a 4-lead electrocardiogram (ECG) and a non-invasive arterial blood pressure monitoring. Arterial blood pressure will then be obtained continuously every minute. Furthermore, a near infrared spectroscopy (NIRS) pulsoxymetry detector will be attached to the forehead of the patient to enable monitoring of the oxygen saturation in the frontal region of the brain throughout the study procedures.
Induction of anaesthesia for surgery will be done according to the local standard operation procedures. No additional medications will be given for this study. Once the patient is anesthetized, according to the randomization either an ET or a LT will be introduced by the attending anaesthetist. Cuff balloons will be filled according to manufacturers recommendation. The pressure of the cuff balloon will be measured and recorded by using a regular cuff pressure manometer. After securing the airway and maintaining anaesthesia the patient will be included to the ultrasound protocol. Ultrasound of the carotid arteries will now be performed. After the ultrasound protocol has been performed, the patient will be re-intubated using the opposite airway device (ET or LT according to the initial airway device), and the ultrasound examination will be performed again for determining differences in carotid artery blood flow. To minimize inter-observer variability the ultrasound protocol will be performed by only one trained radiologist. Ultrasound examinations will be performed as soon as feasible after patients has been monitored, intubated and anaesthetized. Colour flow and spectral Doppler waveform ultrasound images will be obtained from the common carotid arteries. The radiologist performing the ultrasound will be instructed to record blood flow in the carotid arteries using a commercially available portable ultrasound machine. Therefore, a 11- MHz linear array transducer will be placed on the side of the subject’s neck in the transverse orientation using visible anatomic landmarks to identify the carotid artery. In the longitudinal orientation, a pulse-wave tracing of the common carotid artery in the longitudinal orientation will be acquired after the smallest possible sample gate was positioned directly over the center of the common carotid artery 2 cm proximal of the carotid bifurcation. The angle between the ultrasound beam and the longitudinal vessel axis will be kept between 45 and 60°. Images will be acquired from the left and right side. All images and video clips will be stored directly on the ultrasound machine for later retrieval. Pulse-wave measurements will be recorded of both (left/right) common carotid arteries determining peak systolic velocity (PSV), end-diastolic velocity (EDV), and mean diastolic velocity (MDV). Then, in patients with LT, PSV, EDV and MDV will be measured three times (next to one another). After changing the LT to the ET, PSV, EDV and MDV measurements will be repeated three times (next to one another). For further analyses the mean of the respective three measurements (PSV, EDV, MDV) will be used. Standardized forms will be used to collect patient data. Only one, trained physician not involved in the clinical care of the patient will acquire all images. Aiming to keep the time period of duplex scans as short as possible, the duration of duplex examinations will be limited to 15 minutes per patient. Duplex clips and images will be stored on the respective duplex ultrasound machine and all analyses will be performed offline.
Intervention typeDevice
Pharmaceutical study type(s)
Phase
Drug / device / biological / vaccine name(s)
Primary outcome measurePeak systolic velocity, measured using ultrasound 5 min after intubation
Secondary outcome measures1. Mean diastolic velocity (MDV), measured using ultrasound 5 min after intubation
2. Enddiastolic velocity (EDV), measured using ultrasound 5 min after intubation
3. Oxygen saturation, measured using near infrared spectroscopy (NIRS) pulsoxymetry detector 5 min after intubation
Overall study start date07/07/2017
Completion date31/12/2018

Eligibility

Participant type(s)Patient
Age groupAdult
Lower age limit18 Years
SexBoth
Target number of participants20
Key inclusion criteria1. Adult patients with an age of >18 years
2. Informed consent
3. ASA I-II
4. Mallampati Score classification I-II
5. Scheduled for elective surgery for any reason
Key exclusion criteria1. Prior intubation or anaesthesia related adverse events
2. >25% stenosis of the extracranial common and internal carotid arteries
3. Carotid dissections
4. Carotid aneurysms
5. Pre-existing surgeries at carotid arteries or in the area of the neck, throat or laryngeal structures
6. Laparoscopic surgery requiring gas inflation of the abdomen
7. Pregnancy
8. Ward of the state/prisoner
Date of first enrolment24/07/2017
Date of final enrolment31/07/2018

Locations

Countries of recruitment

  • Austria

Study participating centre

University Hospital Krems, Karl Landsteiner University of Health Sciences
Mitterweg 10
Krems
3500
Austria

Sponsor information

Karl Landsteiner University of Health Sciences
Hospital/treatment centre

Dr-Karl-Dorrek-Straße 30
Krems
3500
Austria

Phone +43 (0)2732 / 720 90 - 0
Email office@kl.ac.at
Website http://www.kl.ac.at
ROR logo "ROR" https://ror.org/04t79ze18

Funders

Funder type

University/education

Karl Landsteiner University of Health Sciences

No information available

Results and Publications

Intention to publish date30/06/2019
Individual participant data (IPD) Intention to shareYes
IPD sharing plan summaryAvailable on request
Publication and dissemination planPublication is planned within 12-18 months after the study has started.
IPD sharing planThe datasets generated during and/or analysed during the current study are/will be available upon request from Dr Raphael van Tulder (raphael.van-tulder@meduniwien.ac.at).

Editorial Notes

21/02/2018: The following changes were made:
1. Recruitment end date was changed from 31/01/2018 to 31/07/2018
2. Overall trial end date was changed from 31/01/2018 to 31/12/2018
3. Intention to publish date was changed from 01/12/2018 to 30/06/2019