Thyromental Height Test as a New Method for Prediction of Difficult Intubation in Obese Patients

Medical University of Silesia

Status: Unknown

Conditions: Intubation, Intratracheal; Predictive Value of Tests; Obesity

Treatments: Other: Assesment of intubation parameters during induction of general anaesthesia; Diagnostic Test: Anthropometric measurements during routine preoperative visit

Study type: Observational

Funder types: Other

Identifiers

NCT04439487

TMHT-02

Details and patient eligibility

About

The main objective of this trial is to assess the clinical usefulness of thyromental height test (TMHT) in prediction of difficult intubation in obese patients scheduled for elective surgical procedures. The secondary aim is to evaluate usefulness of other commonly used predictive tests associated with difficult intubation in obese patients.

Full description

Successful and fast intubation are crucial for the safety of general anaesthesia. Failed intubation and acute hypoxia remain among the major contributing factors of anaesthesia related deaths. Difficult intubation prevalence in literature is very inconsistent and varies between 1.5-20% of cases in general population, to even 50% in obese Thai population.

Obesity remains a challenging problem in perioperative care. It is assumed that the airway access may be restricted due to anatomic changes resulting from excess body weight. There are factors like diagnosed obstructive sleep apnoea or large neck circumference that also relate to occurrence of difficult intubation in obese patients.

There is a number of anthropometric scales and tests used for predicting difficult intubation in obese patients. However, none of them appears to be sensitive and specific enough to effectively predict difficult intubation.

Recently, simple and non-invasive test predicting difficult intubation was introduced-thyromental height test (TMHT). It shows promise as a more effective substitution for frequently cited anthropometric measures. It is based on the height between the anterior border of the thyroid cartilage and the anterior border of the mentum, measured while the patient lies in the supine position with closed mouth.

The main objective of this trial is to assess the clinical usefulness of TMHT in prediction of difficult intubation in obese patients scheduled for elective surgical procedures. The secondary aim is to evaluate usefulness of other commonly used predictive tests associated with difficult intubation in obese patients.

Enrollment: 300 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• qualification for elective surgical procedures, requiring general anaesthesia, direct laryngoscopy and intubation
• consent for participation in the trail
• age ≥18 years
• BMI ≥30 kg/m2

Exclusion criteria

• BMI ≤30 kg/m2
• patients overweight due to ascites or tumor
• emergency procedures
• visible anatomic abnormalities
• patients scheduled for awake fibreoptic intubation
• intubation failure
• lack of consent for participation in the trail

Trial design

300 participants in 1 patient group

Obese patients requiring general anesthesia

Description:

Group consists of consecutive, adult, obese patients undergoing elective surgical procedures requiring general anaesthesia, direct laryngoscopy and intubation. All patients undergo general anesthesia according to a standardised protocol. They are preoxygenated with 100% oxygen breathed through a face mask for 3-5 minutes. Induction of general anaesthesia is achieved with propofol 1,5-2 mg·kg-1 (of Ideal Body Weight) and 0,1mg fentanyl or sufentanil 10µg. Muscle relaxation is accomplished with rocuronium 0.6 mg ·kg-1 (of Ideal Body Weight). Depth of muscular blockade is monitored using Train of Four (TOF) method. The first laryngoscopy attempt is performed at TOF 0. The patient is placed in an optimal, sniffing or ramped position as appropriate and a #3 or #4 Macintosh blade is used. Successful intubation is confirmed with bilateral auscultation and capnography.

Treatment:

Diagnostic Test: Anthropometric measurements during routine preoperative visit

Other: Assesment of intubation parameters during induction of general anaesthesia