Current Preoperative Current Preoperative
Airway AssessmentAirway Assessment
Scott Rigdon CRNA MPHScott Rigdon CRNA MPH
Staff CRNA Three Rivers Community Hospital Staff CRNA Three Rivers Community Hospital
Grants Pass, ORGrants Pass, OR
Associate Clinical Faculty Oregon Health Science UniversityAssociate Clinical Faculty Oregon Health Science University
If it were only this easy!!If it were only this easy!!
The Goal of all Preoperative The Goal of all Preoperative Airway AssessmentsAirway Assessments
“From little Acorns Mighty Oaks Do Grow“From little Acorns Mighty Oaks Do Grow””
Why we continually revisit the art Why we continually revisit the art
and science of airway assessmentand science of airway assessment
�� Difficult laryngoscopy / intubation 1.5% to 13% (Various)Difficult laryngoscopy / intubation 1.5% to 13% (Various)
�� The incidence of 24The incidence of 24--h postoperative death: 8.8 per h postoperative death: 8.8 per
10,000. (95’10,000. (95’--97’) (869,483 pt. cohort.) 97’) (869,483 pt. cohort.) AnesthAnesth Feb 05’Feb 05’
�� Anesthesia mortality rates have fallen from two deaths Anesthesia mortality rates have fallen from two deaths
per 10,000 in the 1980s to 1 per 200,000 today.per 10,000 in the 1980s to 1 per 200,000 today.per 10,000 in the 1980s to 1 per 200,000 today.per 10,000 in the 1980s to 1 per 200,000 today.
--Money Magazine, 10/06/09 Money Magazine, 10/06/09 http://money.cnn.com/galleries/2009/moneymag/0910/gallery.bestjobs_highestpaid.moneymag/4.htmlhttp://money.cnn.com/galleries/2009/moneymag/0910/gallery.bestjobs_highestpaid.moneymag/4.html
We are what we repeatedly do. Excellence, then, is not an act, but a habit. We are what we repeatedly do. Excellence, then, is not an act, but a habit.
--AristotleAristotle
Potentially Difficult AirwaysPotentially Difficult Airways
ObjectivesObjectives
1.1. Review and understand modern airway Review and understand modern airway assessment techniques.assessment techniques.
2.2. Review basic statistical terms used to assess Review basic statistical terms used to assess the strength of data. the strength of data. the strength of data. the strength of data.
3.3. Define and discuss the use of the Upper Lip Define and discuss the use of the Upper Lip Bite Test (ULBT). Bite Test (ULBT).
4.4. Understand modern evidenceUnderstand modern evidence--based based implementation of current airway assessment implementation of current airway assessment toolstools. .
Modern Preoperative Airway Modern Preoperative Airway
Assessment toolsAssessment tools
��Modified Mallampati (MMT)Modified Mallampati (MMT)
�� InterInter--incisor distance (IIC)incisor distance (IIC)
Sternomental distance (SMD)Sternomental distance (SMD)�� Sternomental distance (SMD)Sternomental distance (SMD)
�� Thyromental distance (TMD)Thyromental distance (TMD)
**Upper Lip Bite Test (ULBT)****Upper Lip Bite Test (ULBT)**
Modified MallampatiModified Mallampati
Upright, maximal jaw opening, tongueUpright, maximal jaw opening, tongue
protrusion without phonation protrusion without phonation
1. Fauces, pillars, soft palate and uvula visualized1. Fauces, pillars, soft palate and uvula visualized1. Fauces, pillars, soft palate and uvula visualized1. Fauces, pillars, soft palate and uvula visualized
2. Fauces, soft palate, uvula2. Fauces, soft palate, uvula
3. Soft palate, base of uvula3. Soft palate, base of uvula
4. Soft palate not visible4. Soft palate not visible
34,523 pt. meta34,523 pt. meta--analysis. “Used alone, the MMP testanalysis. “Used alone, the MMP test
has limited accuracy for predicting the difficult airwayhas limited accuracy for predicting the difficult airway
and thus is not useful as a single screening test.and thus is not useful as a single screening test.
(Anesth Analg(Anesth Analg 2006;102:18672006;102:1867--78)78)
Interincisor distance (IID)Interincisor distance (IID)
�� Less than or equal to 4.5 cm is Less than or equal to 4.5 cm is
considered a potentially considered a potentially
difficult intubation. difficult intubation.
�� Generally greater than 2.5 to 3 Generally greater than 2.5 to 3
fingerbreadths (depending on fingerbreadths (depending on fingerbreadths (depending on fingerbreadths (depending on
observers fingers) observers fingers)
�� **There is some variation **There is some variation
among studies. among studies.
Thyromental and Sternomental Thyromental and Sternomental
DistanceDistance
TMDTMD
1.1. UprightUpright
SMDSMD
1.1. Supine with neck fully extendedSupine with neck fully extended
2.2. Full neck extensionFull neck extension
3.3. Distance from upper boarder of Distance from upper boarder of
thyroid cartilage (laryngeal thyroid cartilage (laryngeal
prominence), to the boney point prominence), to the boney point
of the mentum. of the mentum.
4.4. Distance < 6.5cm may be Distance < 6.5cm may be
difficultdifficult
**some inter**some inter--study variationstudy variation
2.2. Measure from sternum to boney Measure from sternum to boney
point of mentum. point of mentum.
3.3. <12.5cm is potentially a difficult <12.5cm is potentially a difficult
intubation intubation
**Some inter**Some inter--study variationstudy variation
Cormack & Lehane GradesCormack & Lehane Grades
Class I: the vocal cords are visibleClass I: the vocal cords are visible
Class II the vocals cords are only partly visibleClass II the vocals cords are only partly visible
Class III only the epiglottis is seen Class III only the epiglottis is seen
Class IV the epiglottis cannot be seen. Class IV the epiglottis cannot be seen.
Cormack & Lehane grade 3 and 4 are Cormack & Lehane grade 3 and 4 are
considered Difficult Intubation in the ULBT considered Difficult Intubation in the ULBT
studies reviewed. **Some interstudies reviewed. **Some inter--study study
variation.variation.
Statistical Terms Statistical Terms �� Specificity: Specificity: The percentage of The percentage of correctly predictedcorrectly predicted easy easy laryngoscopieslaryngoscopies as a proportion of as a proportion of
all all laryngoscopieslaryngoscopies that were truly easythat were truly easy. .
�� Sensitivity: Sensitivity: The percentage of The percentage of correctly predicted correctly predicted difficult difficult laryngoscopieslaryngoscopies as a proportion as a proportion of all of all laryngoscopieslaryngoscopies that were truly difficult.that were truly difficult.
�� Positive Predictive Value (PPV): Positive Predictive Value (PPV): The percentage of The percentage of correctly predictedcorrectly predicted difficult difficult laryngoscopieslaryngoscopies as a proportion of all as a proportion of all predicted difficultpredicted difficult laryngoscopieslaryngoscopies. .
�� Negative Predictive Value (NPV): Negative Predictive Value (NPV): The percentage of The percentage of correctly predictedcorrectly predicted easy easy �� Negative Predictive Value (NPV): Negative Predictive Value (NPV): The percentage of The percentage of correctly predictedcorrectly predicted easy easy laryngoscopieslaryngoscopies as a proportion of all as a proportion of all predicted easypredicted easy laryngoscopieslaryngoscopies
�� AccuracyAccuracy: The proportion of correctly predicted : The proportion of correctly predicted easy or difficulteasy or difficult laryngoscopieslaryngoscopies as a as a proportion of all proportion of all laryngoscopieslaryngoscopies. .
�� True Positive: True Positive: A difficult laryngoscopy that had been predicted to be difficult.A difficult laryngoscopy that had been predicted to be difficult.
�� False Positive: False Positive: An easy laryngoscopy that had been predicted to be difficult. An easy laryngoscopy that had been predicted to be difficult.
�� True Negative: True Negative: An easy laryngoscopy that had been predicted to be easy.An easy laryngoscopy that had been predicted to be easy.
�� **False Negative: **False Negative: An difficult laryngoscopy that has been predicted to be easy. An difficult laryngoscopy that has been predicted to be easy.
InterInter--rater Reliabilityrater Reliability
�� Trained raters agree with the "official" or “known” Trained raters agree with the "official" or “known”
assessment tool.assessment tool.
�� Trained raters agree with each otherTrained raters agree with each other..
““A Mallampati 4, is a Mallampati 4, is a Mallampati 4”A Mallampati 4, is a Mallampati 4, is a Mallampati 4”
A Comparison of the Upper Lip Bite Test (a Simple New A Comparison of the Upper Lip Bite Test (a Simple New Technique) with Modified Mallampati Classification in Technique) with Modified Mallampati Classification in Predicting Difficulty in Endotracheal Intubation: A Prospective Predicting Difficulty in Endotracheal Intubation: A Prospective Blinded StudyBlinded Study
�� 300 adult patients300 adult patients
�� Modified Mallampati Vs. ULBTModified Mallampati Vs. ULBT
�� Inclusion Criteria: (>15 yrs)Inclusion Criteria: (>15 yrs)
�� Exclusion Criteria: (<16 yrs), endentulous, unable to open mouth, Exclusion Criteria: (<16 yrs), endentulous, unable to open mouth, laryngeal mass, limitation of cervical movementlaryngeal mass, limitation of cervical movement. .
FindingsFindings
1.1. ULBT significantly higher specificity and accuracy (P < 0.001)ULBT significantly higher specificity and accuracy (P < 0.001)
2.2. Sensitivity, Positive/Negative Predictive Value, no significant differenceSensitivity, Positive/Negative Predictive Value, no significant difference
ConclusionConclusion
“ULBT is an acceptable option for predicting difficult intubation as a “ULBT is an acceptable option for predicting difficult intubation as a
simple, single testsimple, single test.” .”
Upper Lip Bite TestUpper Lip Bite Test
�� Class 1: Class 1: Lower incisors can bite Lower incisors can bite upper lip above vermillion upper lip above vermillion line.line.
�� Class 2:Class 2:�� Class 2:Class 2:Lower incisors can bite Lower incisors can bite upper lip below vermillion upper lip below vermillion line.line.
�� Class 3: Class 3: Lower incisors cannot Lower incisors cannot bite the upper lip.bite the upper lip.
ULBTULBT
�� Class 1Class 1
Class 2Class 2�� Class 2Class 2
�� Class 3Class 3
Poor Visualization During Direct Laryngoscopy and High Upper Lip Bite Poor Visualization During Direct Laryngoscopy and High Upper Lip Bite
Score Are Predictors of Difficult Intubation with the Score Are Predictors of Difficult Intubation with the GlideScopeGlideScope
VideolaryngoscopyVideolaryngoscopy
�� 400 patients. 400 patients.
�� 2 Experienced Anesthesia Residents with at least 30 2 Experienced Anesthesia Residents with at least 30 GlideScopeGlideScope
IntubationsIntubations
�� First attempt DL with MAC Blade and obtain First attempt DL with MAC Blade and obtain LehaneLehane & Cormack Grade& Cormack Grade
�� Second Second GlideScopeGlideScope VideolayrngoscopyVideolayrngoscopy obtain obtain LehaneLehane & Cormack Grade, & Cormack Grade,
then attempt intubationthen attempt intubation
�� First Attempt 342, Second Attempt 48, Third Attempt 9, Failed intubation 1First Attempt 342, Second Attempt 48, Third Attempt 9, Failed intubation 1�� First Attempt 342, Second Attempt 48, Third Attempt 9, Failed intubation 1First Attempt 342, Second Attempt 48, Third Attempt 9, Failed intubation 1
�� ConclusionsConclusions: : High ULBT score (3), High High ULBT score (3), High LehaneLehane & Cormack grade (3,4), & Cormack grade (3,4),
short short sternothyroidsternothyroid distance. May result in “challenging” distance. May result in “challenging” videolaryngoscopyvideolaryngoscopy..
��
�� **Recent significant **Recent significant palatopharyngealpalatopharyngeal injury has been reported with the injury has been reported with the use of use of GlideScopeGlideScope VideolaryngoscopyVideolaryngoscopy. .
�� ChooChoo MK, MK, YeoYeo VS, See JJ. Another Complication associated with VS, See JJ. Another Complication associated with videolayngoscopyvideolayngoscopy. Can J . Can J AnaesthAnaesth 2007;54:3222007;54:322--44
�� Cooper RM. Complications Associated with the use of the Cooper RM. Complications Associated with the use of the GlideScopeGlideScope VideolaryngoscopeVideolaryngoscope. Can J . Can J AnaesthAnaesth2007;54:542007;54:54--7.7.
�� Tremblay MH, et al. Poor Visualization During Direct Laryngoscopy and High Upper Lip Bite Score Are Predictors Tremblay MH, et al. Poor Visualization During Direct Laryngoscopy and High Upper Lip Bite Score Are Predictors
of Difficult Intubation with the of Difficult Intubation with the GlideScopeGlideScope VideolaryngoscopyVideolaryngoscopy. Anesth Analg 2008;106:1495. Anesth Analg 2008;106:1495--1500.1500.
Current ULBT StudiesCurrent ULBT Studies�� Khan HZ, Et al. The Diagnostic Value of the Upper Lip Bite Test combined with Sternomental Distance, Thyromental Khan HZ, Et al. The Diagnostic Value of the Upper Lip Bite Test combined with Sternomental Distance, Thyromental
Distance, and Distance, and InterincisorInterincisor Distance for Prediction of Easy Laryngoscopy and Intubation: A Prospective Study. Anesth Distance for Prediction of Easy Laryngoscopy and Intubation: A Prospective Study. Anesth Analg 2009;109:822Analg 2009;109:822--4. 4. Conclusion:Conclusion: Specificity and Accuracy of ULBT is significantly higher than other single tests. Specificity and Accuracy of ULBT is significantly higher than other single tests. However, ULBT combined with the other tests “could” more reliably predict easy laryngoscopy or intubation. However, ULBT combined with the other tests “could” more reliably predict easy laryngoscopy or intubation.
�� Jang JH, Shin OY, Kang HJ. Prediction of Difficulty in Endotracheal Intubation in Patients with Obstructive Sleep Apnea: Jang JH, Shin OY, Kang HJ. Prediction of Difficulty in Endotracheal Intubation in Patients with Obstructive Sleep Apnea: Comparison of Modified Mallampati Test and Upper Lip Bite Test.Comparison of Modified Mallampati Test and Upper Lip Bite Test. Korean J Korean J AnesthesiolAnesthesiol. 2006 Apr;50(4):367. 2006 Apr;50(4):367--372. 372.
ConclusionConclusion: MMT and ULBT have a poor diagnostic accuracy for predicting difficult intubation in OSA patients as a : MMT and ULBT have a poor diagnostic accuracy for predicting difficult intubation in OSA patients as a single bedside screening test. single bedside screening test.
�� BhatBhat RR, RR, MIshraMIshra SK, SK, BadheBadhe A. Comparison of Upper Lip Bite Test and Modified Mallampati Classification in Predicting A. Comparison of Upper Lip Bite Test and Modified Mallampati Classification in Predicting Difficult Intubation. The Interne Journal of Anesthesiology. 2007; Volume 13 (1). Difficult Intubation. The Interne Journal of Anesthesiology. 2007; Volume 13 (1). Conclusion:Conclusion: A combination of Upper A combination of Upper Lip Bite Test and Modified Mallampati Test in parallel is more sensitive, specific and has a higher discriminative power Lip Bite Test and Modified Mallampati Test in parallel is more sensitive, specific and has a higher discriminative power which is clinically relevant than Modified Mallampati Test or ULBT alone. Upper Lip Bite Test and Modified Mallampati which is clinically relevant than Modified Mallampati Test or ULBT alone. Upper Lip Bite Test and Modified Mallampati which is clinically relevant than Modified Mallampati Test or ULBT alone. Upper Lip Bite Test and Modified Mallampati which is clinically relevant than Modified Mallampati Test or ULBT alone. Upper Lip Bite Test and Modified Mallampati Test alone, in parallel and series are good predictors of possible easy intubation rather than difficult intubation.Test alone, in parallel and series are good predictors of possible easy intubation rather than difficult intubation.
�� Leopold H.J, Leopold H.J, EberhartEberhart, Christian Arndt: The Reliability and Validity of the Upper Lip Bite Test Compared with the , Christian Arndt: The Reliability and Validity of the Upper Lip Bite Test Compared with the Mallampati Classification to Predict Difficult Laryngoscopy: An external Prospective Evaluation. Anesth Analg 2005; Mallampati Classification to Predict Difficult Laryngoscopy: An external Prospective Evaluation. Anesth Analg 2005; 101:284101:284--9. 9. Conclusion:Conclusion: 1425 patients, Both MMT & ULBT are poor predictors of Difficult intubation as single tests. 1425 patients, Both MMT & ULBT are poor predictors of Difficult intubation as single tests.
�� Khan HZ, Et al. The Diagnostic Value of the Upper Lip Bite Test combined with Sternomental Distance, Thyromental Khan HZ, Et al. The Diagnostic Value of the Upper Lip Bite Test combined with Sternomental Distance, Thyromental Distance, and Distance, and InterincisorInterincisor Distance for Prediction of Easy Laryngoscopy and Intubation: A Prospective Study. Anesth Distance for Prediction of Easy Laryngoscopy and Intubation: A Prospective Study. Anesth Analg 2009;109:822Analg 2009;109:822--4. 4. Conclusion:Conclusion: Specificity and Accuracy of ULBT is significantly higher than other single tests. Specificity and Accuracy of ULBT is significantly higher than other single tests. However, ULBT combined with the other tests “could” more reliably predict easy laryngoscopy or intubation. However, ULBT combined with the other tests “could” more reliably predict easy laryngoscopy or intubation.
�� Khan HZ, et al. Easy Endotracheal Intubation of a Patient Suffering from Both Cushing’s and Nelson’s Syndromes Khan HZ, et al. Easy Endotracheal Intubation of a Patient Suffering from Both Cushing’s and Nelson’s Syndromes Predicted by the Upper Lip Bite Test Despite a Mallampati Class 4 Airway. Anesth Analg 2007;105:786Predicted by the Upper Lip Bite Test Despite a Mallampati Class 4 Airway. Anesth Analg 2007;105:786--77
Conclusion:Conclusion: Achieved L&C Grade 1 and all went well with case. However, letter backlash for lack of best practice Achieved L&C Grade 1 and all went well with case. However, letter backlash for lack of best practice application for the patient as patient was induced and direct laryngoscopy rather than a safer awake induction. application for the patient as patient was induced and direct laryngoscopy rather than a safer awake induction.
Current ULBT StudiesCurrent ULBT Studies
�� Hester CE, et al. A comparison of preoperative airway assessment techniques: the modified Mallampati and the Hester CE, et al. A comparison of preoperative airway assessment techniques: the modified Mallampati and the
upper lip bite test AANA Journal. 2007 75(3):177upper lip bite test AANA Journal. 2007 75(3):177--82. 82. Conclusion:Conclusion: ULBT appears valuable bedside test, further ULBT appears valuable bedside test, further
research needed.research needed.
�� Tremblay MH, et al. Poor Visualization During Direct Laryngoscopy and High Upper Lip Bite Score Are Predictors Tremblay MH, et al. Poor Visualization During Direct Laryngoscopy and High Upper Lip Bite Score Are Predictors
of Difficult Intubation with the of Difficult Intubation with the GlideScopeGlideScope VideolaryngoscopyVideolaryngoscopy. Anesth Analg 2008;106:1495. Anesth Analg 2008;106:1495--1500. 1500. Conclusion:Conclusion:
Despite Despite GlideScopeGlideScope high success rate, increased ULBT, high success rate, increased ULBT, sternothyroidsternothyroid distance or distance or LehaneLehane / Cormack score is / Cormack score is
likely to be more “challenging” with likely to be more “challenging” with GlideScopeGlideScope. (. (EgEg.) Attempts: 400 pt.’s, 342 1.) Attempts: 400 pt.’s, 342 1stst attempt, 48 2attempt, 48 2ndnd attempt, 9 3attempt, 9 3rdrd
attempt, 1 failure to attempt, 1 failure to intubateintubate. Study also cited other studies with significant . Study also cited other studies with significant palatopharyngealpalatopharyngeal injury from injury from
VideolaryngoscopyVideolaryngoscopy. . VideolaryngoscopyVideolaryngoscopy. .
�� SalimiSalimi A, A, FarzaneganFarzanegan B, B, RastegarpourRastegarpour A, A, KolahiKolahi AA. Comparison of the upper lip bite test with measurement of AA. Comparison of the upper lip bite test with measurement of
thyromentalthyromental distance for prediction of difficult intubations. distance for prediction of difficult intubations. ActaActa AnaesthesiologicaAnaesthesiologica TaiwanicaTaiwanica. 46(2):61. 46(2):61--5, 2008 5, 2008
Jun. Jun. Conclusion:Conclusion: The findings suggest that the sensitivity of the ULBT and TMD for predicting difficult intubations The findings suggest that the sensitivity of the ULBT and TMD for predicting difficult intubations
may not be significantly different, but the specificity of the ULBT is significantly higher. The positive predictive may not be significantly different, but the specificity of the ULBT is significantly higher. The positive predictive
value of the ULBT was significantly higher than that of TMD, signifying that a positive ULBT is more predictive of a value of the ULBT was significantly higher than that of TMD, signifying that a positive ULBT is more predictive of a
difficult airway than is a positive TMD.difficult airway than is a positive TMD.
Current Literature FindingsCurrent Literature Findings
�� Modern Efficacious Airway assessments include: MMP, ULBT, TMD, SMD, IID.Modern Efficacious Airway assessments include: MMP, ULBT, TMD, SMD, IID.
�� ULBT is as good or better than any single bedside airway assessment tool for ULBT is as good or better than any single bedside airway assessment tool for predicting predicting easyeasy intubation.intubation.
�� ULBT appears to be statistically best at predicting ULBT appears to be statistically best at predicting easyeasy intubation or laryngoscopy as intubation or laryngoscopy as a single test. a single test.
�� Using a combination of airway assessment tools appears to be the best method for Using a combination of airway assessment tools appears to be the best method for predicting easy and difficult intubation / laryngoscopy. predicting easy and difficult intubation / laryngoscopy.
�� There is still no preoperative airway assessment which reliably (statistically) predicts There is still no preoperative airway assessment which reliably (statistically) predicts difficult intubation. difficult intubation.
~~Anesthesia practice is as much art as scienceAnesthesia practice is as much art as science~~
Personal Conjecture: “Personal Conjecture: “the formation or expression of an opinion or theory without sufficient evidence for proof.” the formation or expression of an opinion or theory without sufficient evidence for proof.”
--dictionary.comdictionary.com
Want to be involved in a study?Want to be involved in a study?
�� We are looking for CRNAs who want to participate in a We are looking for CRNAs who want to participate in a
prospective clinical study involving the use of the ULBT prospective clinical study involving the use of the ULBT
for preoperative airway assessment. for preoperative airway assessment.
�� Easy data collection, I will collaborate with the IRB Easy data collection, I will collaborate with the IRB �� Easy data collection, I will collaborate with the IRB Easy data collection, I will collaborate with the IRB
paperwork. (exempt study with no patient identifiers). paperwork. (exempt study with no patient identifiers).
�� If you provide general anesthesia services as a part of If you provide general anesthesia services as a part of
your practice and would like to be involved or have any your practice and would like to be involved or have any
questions, please contact me at:questions, please contact me at:
[email protected]@hotmail.com
In Addition to ORANA In Addition to ORANA
Consider Supporting Consider Supporting
“Champions of Research and Development”“Champions of Research and Development”
Questions ??Questions ??
The Quality of a person’s life is in direct proportion to their commitment to excellence, The Quality of a person’s life is in direct proportion to their commitment to excellence, regardless of their chosen field or endeavor.regardless of their chosen field or endeavor.
--Vince LombardiVince Lombardi
