Difficult; Intubation, in Pregnancy Clinical Trial
Official title:
Does Neck Circumference Help to Predict Difficult Airway in Obstetric Patients?
Failed intubation and ventilation in obstetrics remains one of the most common causes of
death directly related to anesthesia. The reported incidence of failed intubation in
obstetrics is 1:300, which is significantly higher than that in the non-obstetric
population. A clinical screening test with high sensitivity and specificity for prediction
of difficult airway may help reduce morbidity and mortality from general anesthesia. Few
studies have identified increased neck circumference as the best single predictor of
problematic intubation. However the cutoff point of this test for identifying patients at
high risk of difficult intubation is not clear.
The aim of this study is to determine the optimal cutoff point, which validates prediction
of difficult ventilation and/or intubation for obstetric patients. Preoperative airway
assessment will be done including neck circumference. Intraoperative difficult ventilation
and/or intubation will be recorded. Optimal cutoff point of neck circumference will be
calculated by Receiver Operating characteristics (ROC) curve.
In this prospective study, patients will be assessed by the anaesthetist preoperatively and
asked about their medical history including detailed history of obstructive sleep apnea
(OSA) and snoring. Physical examination including weight,height &BMI .
Airway assessment will include:
1. Maximum mouth opening measured as interincisor gap (mm).
2. Sternomental distance measured as the straight distance between the upper border of
manubrium sterni and the bony point of the mentum with the head in full extension and
the mouth is closed (cm).
3. Hyomental distance measured from just above the hyoid bone to the tip to the
anterior-most part of the mentum in both neutral position and with maximum head
extension (cm). Hence, hyomental distance ratio (HMDR) will be calculated.
4. Thyromental distance measured as the distance from the thyroid notch to the inner
margin of the mental prominence when the head is fully extended (cm).
5. Extended Mallampati Score (EMS) in sitting position with full extension of
craniocervical junction with phonation (class I: Entire Uvula is clearly visible; class
II: Upper half of the uvula is visible; class III: soft and hard palate clearly
visible; and class IV: Only hard palate is visible).
6. Neck Circumference at the level of the thyroid cartilage (cm).
7. Condition of the teeth (Protrusion, loose, missing).
8. Mandibular protrusion test to detect temporomandibular joint mobility measured as
ability to move the lower teeth in front of the upper teeth.
Intubation will be considered difficult if the Intubation Difficulty Scale ( IDS) is equal
or more than 5 .
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Observational Model: Cohort, Time Perspective: Prospective