The Effect of Supraglottic Airway Insertion on the Accuracy of Cricothyroid Membrane Identification in Females

The Effect of Supraglottic Airway Insertion on the Accuracy of Cricothyroid Membrane Identification in Females- a Prospective Observational Study.

Prospective, observational, study that will examine if a sited supraglottic airway (the igel) will increase the accuracy of identifying the cricothyroid membrane in female patients.

Consented patients that meet inclusion criteria are assessed by clinicians under general anaesthesia with and without a supraglottic airway in situ. The accuracy of CTM identification by palpation will be evaluated using ultrasound.

Study Overview

• Status: Completed
• Conditions: Airway Obstruction

Detailed Description

Palpation of the airway structures results in misidentification of the cricothyroid membrane (CTM) in a high proportion of women. Female front of neck anatomy is less distinct compared to males with reduced angulation of the laryngeal cartilages making it harder to distinguish the relevant landmarks. In obese patients, overlying subcutaneous tissue compounds this problem and several studies have demonstrated poor success identifying the CTM by palpation in this population. Supraglottic airway device (SAD) insertion precedes emergency front of neck access attempts in the stepwise progression from failed intubation to cricothyroidotomy. The nature and clinical implication of SAD insertion on cricothyroidotomy remain unstudied.

Sixty four patients will undergo front of neck airway assessment by volunteer clinicians with and without a SAD in situ (control and SAD assessments, within-subjects design). The patients are fasting women presenting for routine gynaecological surgery. Eight anaesthetists, at different levels of training, will perform eight individual CTM assessments with and without the SAD in situ.

Ultrasound images will be captured in the sagittal plane immediately before and after supraglottic airway insertion. Images are then downloaded, anonymised and randomised for blinded digital analysis.

• Study Type: Observational
• Enrollment (Actual): 64

Contacts and Locations

Study Locations

• Ireland
  • Dublin, Ireland
    • The Rotunda Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: N/A
• Genders Eligible for Study: Female

• Sampling Method: Non-Probability Sample

Study Population

women attending for routine gynaecological surgery

Description

Inclusion Criteria:

• Women attending for routine surgery

Exclusion Criteria:

• unable to give informed consent
• abnormal neck anatomy
• history of gastroesophageal reflux
• history of neck surgery or radiotherapy
• contraindication to supraglottic airway device insertion

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Study group; CTM assessed with supraglottic airway in situ and without

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
accurate identification of the cricothyroid membrane	accuracy of cricothyroid membrane identification, measured as either successful identification or unsuccessful (binary outcome). A successful identification is within 5mm of the midline and within the upper and lower borders of the cricothyroid membrane as measured using ultrasound.	At clinician assessment, on the day of patient recruitment.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Accurate identification of the midline of the neck	Accurate identification of the midline of the neck, binary outcome. A successful identification is within 5mm of the midline of the cricothyroid membrane as measured using ultrasound.	At clinician assessment, on the day of patient recruitment.
Difficulty of cricothyroid membrane assessment	Difficulty of assessing the cricothyroid membrane as graded subjectively by the clinician using a visual analogue scale (VAS) where '0' is the easiest possible assessment of the location of the cricothyroid membrane and '10' is the most difficult possible assessment of the location of the cricothyroid membrane.	At clinician assessment, on the day of patient recruitment.
Time taken to attempt localisation of the cricothyroid membrane	The time taken in seconds to attempt localisation of the cricothyroid membrane	At clinician assessment, on the day of patient recruitment.
Distance from clinician assessment to actual cricothyroid membrane location	The distance measured from the clinicians estimate of where the cricothyroid membrane is to where the actual location of the CTM is using ultrasound and measured in millimetres	On blinded, retrospective ultrasound analysis of images captured at the time of clinician assessment of the cricothyroid membrane. Blinded retrospective ultrasound assessment is to take place within 3 months of patient recruitment
The distance from the skin to the first tracheal ring	The distance from the skin to the superficial surface of the first tracheal ring measured in millimetres using digital analysis of ultrasound images	On blinded, retrospective ultrasound analysis of images captured at the time of clinician assessment of the cricothyroid membrane. Blinded retrospective ultrasound assessment is to take place within 3 months of patient recruitment
The distance from the skin to the cricoid cartilage	The distance from the skin to the superficial surface of the first tracheal ring measured in millimetres using digital analysis of ultrasound images	On blinded, retrospective ultrasound analysis of images captured at the time of clinician assessment of the cricothyroid membrane. Blinded retrospective ultrasound assessment is to take place within 3 months of patient recruitment
The angle between the surface tissue interface of the cricothyroid membrane and the trachea	The angle between the surface tissue interface of the cricothyroid membrane and the trachea measured in degrees using digital analysis of ultrasound images	On blinded, retrospective ultrasound analysis of images captured at the time of clinician assessment of the cricothyroid membrane. Blinded retrospective ultrasound assessment is to take place within 3 months of patient recruitment

Collaborators and Investigators

• Sponsor: The Rotunda Hospital
• Investigators: Study Director: Conan McCaul, Prof

Study record dates

Study Major Dates

• Study Start (Actual): January 31, 2017
• Primary Completion (Actual): March 31, 2017
• Study Completion (Actual): March 31, 2017

Study Registration Dates

• First Submitted: March 25, 2017
• First Submitted That Met QC Criteria: April 3, 2017
• First Posted (Actual): April 7, 2017

Study Record Updates

• Last Update Posted (Actual): September 25, 2018
• Last Update Submitted That Met QC Criteria: September 23, 2018
• Last Verified: September 1, 2018

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Respiration Disorders; Respiratory Insufficiency; Airway Obstruction
• Other Study ID Numbers: REC-2017-001

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No