1. Background
•Difficult visualization of the larynx
(DVL) is a major cause of difficult
intubation in many patients.
•Recently, Takenaka et al. defined
the ratio of the HMD in the neutral
position and at the extreme of
head extension as the hyomental
distance ratio (HMDR) and
demonstrated that it was a good
predictor of a reduced
occipitoatlantoaxial (OAA)
complex extension capacity in
patients with rheumatoid arthritis.
•An assessment of the extension
capacity of the OAA complex is an
important component of
preoperative tests for predicting
DVL.
•However, no study has quantified
its diagnostic validity for predicting
DVL.
To determine usefulness of
hyomental distance (HMD) ratio
(HMDR) in predicting
difficult laryngoscopy
in Emergency department (ED)
endotracheal intubation, by
examining following airway
predictors, the modified Cormack
and Lehane scale and HMDR.
Aims & Objectives
Methods Conclusion
Figure 1. Method for measuring
the hyomental distance ratio
(HMDR).
HYOMENTAL DISTANCE RATIO AS A DIAGNOSTIC PREDICTOR
OF DIFFICULT LARYNGOSCOPY IN EMERGENCY DEPARTMENT
ENDOTRACHEAL INTUBATION.
Dr. Maruteshwar Reddy; Dr. Nishanth Hiremath*; Dr. Srihari Cattamanchi;
Dr. T.V. Ramakrishnan.
Sri Ramchandra Medical College & Research Institute, Porur, Chennai – 600116. Tamil Nadu. India.
Results
Dr. Maruteshwar Reddy; Mobile: +91-9962936505; Email id: winsomedoctor@gmail.com
Study Design: A prospective
observational study.
Settings: Accident & Emergency
Department of Sri Ramachandra
Medical Centre, Chennai.
Duration: One Month - January
2010.
Inclusion Criteria: All non-
traumatic patients registered in ED
and undergoing endotracheal
intubation at ED were included in
the study.
Exclusion Criteria: All trauma
patients, gross anatomical
abnormality, recent surgery of the
head and neck, upper airway
disease (e.g., maxillofacial fracture
or tumors), loose teeth, or those
requiring a rapid sequence or
awake intubation were excluded
from the study.
Methodology: HMDR is defined
as ratio of HMD at extreme of
head extension to that in neutral
position.
•ED physician performing
endotracheal intubation graded
views using modified Cormack and
Lehane scale and were blinded to
results of airway evaluation.
•Difficult Visualization of Larynx
(DVL) was defined as Grade 3 or 4
views.
Sampling Technique: Convinient
sampling technique employed.
Instrument used: A proforma was
used.
Statistical analysis: performed
using SPSS ver.15.0.
•A total of 26 patients were included
in study, with 15 males (57.6%) and
mean age of 43.96.
•Mean height was 171.34 cms,
mean weight was 75.84 kgs and
mean BMI was 26.23.
•Mean HMD was 7.23 with SD of
2.121 and range of 6 to 9.
•Mean HMD with extreme extension
of head was 8.60 with SD of 2.828
and range of 7 to 11.
•Mean HMDR was 1.184 with SD of
0.183 and range of 1.07 to 1.33.
•Mean modified Cormack and
Lehane scale was 2.0 with SD of
2.121 and range of 1 to 4.
•Larynx was difficult to visualize in
10 (38.46%) patients.
•No failed intubations observed in
the study.
•HDMR was 83.3% sensitive, 100%
specific, positive predictive value of
100% and negative predictive value
of 87.5%.
In conclusion, we demonstrated
that HMDR is highly sensitive and
specific and clinically is a reliable
predictor of difficult visualization
of larynx in an ED & that value of
1.2 can be used as test threshold.