Your SlideShare is downloading. ×
Airway manegement
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×

Introducing the official SlideShare app

Stunning, full-screen experience for iPhone and Android

Text the download link to your phone

Standard text messaging rates apply

Airway manegement

551
views

Published on

Published in: Business, Economy & Finance

0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
551
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
14
Comments
0
Likes
1
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. IntroductionWhen temporary mechanical ventilation is required, either in thetreatment of respiratory failure, or during surgery with muscularrelaxation, endotracheal intubation is usually the preferred methodof airway management.Why is this the preferred means of airway management?The primary reason is that it provides a "protected" airway.Protected from what you ask?Well, protected from introduction of foreign matter, particularlygastric contents.The accurate placement of an endotracheal tube requires skill.Usually the patient is rendered unconscious and immobile (includingparalysis of the muscles of respiration) for the placement. Obviouslyinability to rapidly obtain control of the patients airway in thissetting would be "bad" if not lethal.The airway examination is an effort to identify those patients inwhom conventional endotracheal intubation will be difficult. It isvitally important to recognize such patients BEFORE administeringmedications that induce apnea.( Lack of breathing)Endotracheal Intubationmohammad reza rajabi Page 1 4/3/2012
  • 2. Endotracheal Tube AcknowledgementsThis educational site was developed byTammy Euliano, MD, Associate Professor of Anesthesiologywith the assistance offuture doctor Amy Leeprogrammers Karthik Paladugu and Rick Lockwoodgraphic artist future doctor Christopher Hurt.Major contributions were provided byIlona Schmalfuss, MD, Assistant Professor of RadiologyJeremy Melker, MD, Otolaryngology Resident.Funding was provided by theUniversity of Florida College of Medicine Education Committee.mohammad reza rajabi Page 2 4/3/2012
  • 3. Aspiration of Gastric ContentsThe risk of passive reflux of gastric contents into the pharynx isincreased when the stomach is full. If the gag reflex has beenblunted (by alcohol ingestion, decreased mental status ormedications), the acidic volume can make its way into the tracheacausing potentially extensive damage. Aspiration PreventionIn this case, which of the following could reduce the risk ofaspiration and its consequences? Wait 6 hours before proceeding keeping the patient NPO Yes No(yes) Incorrect! - Nil per osWhile this will help for elective surgery patients, trauma patients andthose with acute GI problems will not empty their stomachs well. Inaddition this operation should not be postponed for any length oftime due to the risk of appendix rupture and/or sepsis.(no)Correct!While a 6-hour NPO period is ideal, this surgery should not bepostponed. Administration of a "non-particulate" antacid Yes No(yes)Correct ! - Non-particulate antacidMany would advocate having the patient drink 15-30cc sodiumcitrate or bicitra within 30 minutes of induction of anesthesia.Though this increases the stomach volume, it is actually protectivemohammad reza rajabi Page 3 4/3/2012
  • 4. as it raises the pH of the stomach contents, reducing injury to thelung in the event of an aspiration.(no)Incorrect ! - Non-particulate antacidMany would advocate having the patient drink 15-30cc sodiumcitrate or bicitra within 30 minutes of induction of anesthesia.Though this increases the stomach volume, it is actually protectiveas it raises the pH of the stomach contents, reducing injury to thelung in the event of an aspiration Administration of H2 blockers Yes No(yes)Correct ! - H2 BlockersThe onset time of these medications is 30+ minutes, and even thenthey do not affect the pH of the volume already in the stomach.However, new fluid will be secreted into the stomach at a higher pH,perhaps increasing the overall pH by the time of emergence fromanesthesia (the other time at which patients are at risk foraspiration).(no)Incorrect ! - H2 BlockersThe onset time of these medications is 30+ minutes, and even thenthey do not affect the pH of the volume already in the stomach.However, new fluid will be secreted into the stomach at a higher pH,perhaps increasing the overall pH by the time of emergence fromanesthesia (the other time at which patients are at risk foraspiration).Administration of metoclopramide Yes Nomohammad reza rajabi Page 4 4/3/2012
  • 5. (yes)Correct! - MetoclopramideMetoclopramide speeds gastric emptying and increases the loweresophageal sphincter (LES) pressure. While the latter is helpful atreducing the risk of aspiration within minutes, stomach volumereduction takes more time. This emptying should occur, however,and can reduce the risk of aspiration during emergence andextubation at the end of the operation. There are some risks tometoclopramide so, as with everything, a risk:benefit evaluationmust be performed.(no)Incorrect! - MetoclopramideMetoclopramide speeds gastric emptying and increases the loweresophageal sphincter (LES) pressure. While the latter is helpful atreducing the risk of aspiration within minutes, stomach volumereduction takes more time. This emptying should occur, however,and can reduce the risk of aspiration during emergence andextubation at the end of the operation. There are some risks tometoclopramide so, as with everything, a risk:benefit evaluationmust be performed. Rapid Sequence Induction Yes No(yes)Correct! - Rapid Sequence InductionFollowing pre-oxygenation, the patient is put to sleep with a rapidacting IV induction agent such as sodium thiopental, immediatelyfollowed by succinylcholine (or other rapid-acting agent), applicationof cricoid pressure , and intubation of the trachea.Positive pressure mask ventilation is not performed to avoidincreasing gastric volume. The purpose of this technique is tominimize the duration of impaired gag reflex prior to intubation Cricoid Pressure during intubation Yes Nomohammad reza rajabi Page 5 4/3/2012
  • 6. (no) Incorrect! - Cricoid Pressure during IntubationAn assistant identifies the cricoid ring and applies pressure,compressing the esophagus against the underlying vertebralbody. This prevents passive reflux of gastric contents into thelung. How much pressure to apply is a continuing question,current recommendations suggest approximately 10 Newtons(1 kg) of force (mild discomfort for the patient), as the inductionmedications are being administered. Once the patient losesconsciousness, the cricoid pressure should be increased toapproximately 30 Newtons (3 kg). It is possible for this pressureto make intubation more difficult and some reduction in forcemay be necessary.(yes)Correct! - Cricoid Pressure during IntubationAn assistant identifies the cricoid ring and applies pressure,compressing the esophagus against the underlying vertebralbody. This prevents passive reflux of gastric contents into thelung. How much pressure to apply is a continuing question,current recommendations suggest approximately 10 Newtons(1 kg) of force (mild discomfort for the patient), as the inductionmedications are being administered. Once the patient losesconsciousness, the cricoid pressure should be increased toapproximately 30 Newtons (3 kg). It is possible for this pressureto make intubation more difficult and some reduction in force Endotracheal IntubationIntubation is typically performed under direct visualization. That is,by looking through the mouth directly at the vocal cords (directlaryngoscopy), and watching the endotracheal tube pass through thecords and into the trachea. However, there is no direct line-of-sightfrom the mouth to the vocal cords.Check in a mirror or examine a friend (preferably one who has noteaten onions recently), even with the mouth maximally opened andtongue extended you cannot see the vocal cords, in fact only rarelycan you see the epiglottis.mohammad reza rajabi Page 6 4/3/2012
  • 7. Mallampati ClassificationActually, the amount of the posterior pharynx you can visualize isimportant and correlates with the difficulty of intubation.Visualization of the pharynx is obscured by a large tongue (relativeto the size of the mouth), which also interferes with visualization ofthe larynx on laryngoscopy. The Mallampati Classification is based onthe structures visualized with maximal mouth opening and tongueprotrusion in the sitting position (originally described withoutphonation, but others have suggested minimum MallampatiClassification with or without phonation best correlates withintubation difficulty).mohammad reza rajabi Page 7 4/3/2012
  • 8. Class I: soft palate, fauces, uvula, pillarsClass II: soft palate, fauces, portion of uvulaClass III: soft palate, base of uvulaClass IV: hard palate only Other Predictors of Difficult Intubation  Obesity – body weight > 110kg  Mouth opening – inter-incisor distance < 4cm in an adult  Ability to prognath – a large overbite, or the inability to shift the lower incisors in front of the upper incisors  Thyromental distance – The distance from the thyroid cartilage to the mentum (tip of the chin) should be > 6.5-7 cm.  Mentum-Hyoid distance – Similar to thyromental distance, and should be at least 3-4 finger-breadths.Many other factors have been investigated with variable results. Other factors that may indicate a difficult intubation  Sternomental distance – Similar to above, measured from the sternum to the tip of the mandible with the head extended. This measure is influenced by neck extension. Should be >12.5cm.  Mandibulohyoid distance – the vertical distance between the mandible and the hyoid bone, determined radiographically. This may be increased with a short mandibular ramus or a caudally located hyoid bone. Such an increase in this distance may be associated with difficult intubation {Chou 1993}  Thyrosternal distance – <8cm may suggest difficulty, probably related to the caudally located hyoid as above.mohammad reza rajabi Page 8 4/3/2012
  • 9.  Various radiographic measurements of the cervical spine, its alignment with airway structures and the atlanto-occipital joint. PositioningTo obtain a direct line of sight, the patient is positioned in the"sniffing position." The neck is flexed at the lower cervical spine andextended at the atlanto-occipital joint. This flexion and extension isamplified during laryngoscopy.The patient’s neck mobility should be assessed preoperatively byhaving them flex and extend their head maximally. The range ofmotion should be more than 90°. Motion less than 80° may triple therisk of a poor view at laryngoscopy.mohammad reza rajabi Page 9 4/3/2012
  • 10. Direct LaryngoscopyThen a laryngoscope is used to pull the lower jaw and tongue up andout of the way.The metal blade is passed into the mouth to the level of theepiglottis, then with an anterior and caudad motion (ie toward theedge of the ceiling across the room) , the lower jaw is elevated,allowing visualization of the glottic structures.( The glottis is thestructures of phonation including the vocal cords and surroundingstructures.) In most patients this results in a clear view of the larynxand the endotracheal tube is passed through the vocal cords underdirect visualization.mohammad reza rajabi Page 10 4/3/2012
  • 11. Laryngoscopy GradesIn most patients Direct Laryngoscopy results in a clear view of thelarynx. The laryngeal view has been classified by Cormack andLehane as follows:Grade 1: Full view of the glottisGrade 2: Only the posterior commissure is visibleGrade 3: Only the epiglottis is seenGrade 4: No epiglottis or glottis structure visible Airway ReviewWhat might make Direct Laryngoscopy and Intubation more difficult? Inability to open the mouth Yes No(yes)Correct!There must be room to place the laryngoscope in the mouth…usuallyat least 3 finger breadths in the adult.(no)Incorrect!There must be room to place the laryngoscope in the mouth…usuallyat least 3 finger breadths in the adult.mohammad reza rajabi Page 11 4/3/2012
  • 12. Inability to extend the neck Yes No(yes)Correct!The "sniffing position" requires significant neck extension.(no)Incorrect!The "sniffing position" requires significant neck extension. Inability to breathe through the nose Yes No(no)Correct!Unless a nasal intubation is planned.(yes)Incorrect!Unless a nasal intubation is planned. Large tongue Yes No(yes)Correct!Also if it is immobile, as from radiation therapy.(no)Incorrect!Also if it is immobile, as from radiation therapy. Redundant pharyngeal tissue Yes No(yes)Correct!!This occurs with obesity, and is often suggested by a history ofsnoring and/or obstructive sleep apnea.mohammad reza rajabi Page 12 4/3/2012
  • 13. (no)Incorrect!This occurs with obesity, and is often suggested by a history ofsnoring and/or obstructive sleep apnea. Case 2 : Abnormal ExamA healthy 25-year-old man is scheduled to have a shoulder repairrequiring general anesthesia.Lets review his airway examination.What would you like the patient to do: Open his mouth as wide as possible Extend his neck as far as possible without pain View from the sidemohammad reza rajabi Page 13 4/3/2012
  • 14. Open MouthThis patients mouth opening is 2 finger-breadths, the soft palate isbarely visible on maximal mouth opening.Neckmohammad reza rajabi Page 14 4/3/2012
  • 15. View from the side2 finger-breadths fit between the tip of the chin and the neck. Airway Examination Mouth opening Normal Reduced What is mouth opening? (normal)Incorrectit is less than 3 finger breadths.mohammad reza rajabi Page 15 4/3/2012
  • 16. (reduced)CorrectThe mouth opening is less than 3 finger-breadths.Open MouthThe inter-incisor distance on maximal mouth opening. Should be >4cm in an adult, or 3-4 of the patients finger-breadths.This patients mouth opening is 2 finger breadths, the soft palate isbarely visible on maximal mouth opening. Mallampati Score I II III IV What is Mallampati Score?mohammad reza rajabi Page 16 4/3/2012
  • 17. (I)IncorrectThe uvula cannot be seen. (II)IncorrectNot even the top of the uvula is visible. (III)YesAll structures visible up to the soft palate is a Mallampati Class III. (IV)IncorrectThe soft palate is visible. Mentum-Hyoid distance Normal Reduced What distance?(normal)Incorrect3 finger-breadths is normal, this patient has only 2.(reduced)Yesthis is less than the normal 3 finger-breadths.View from the side2 finger-breadths fit between the tip of the chin and the neck.mohammad reza rajabi Page 17 4/3/2012
  • 18. Neck Extension Normal Reduced What is neck extension?(normal)CorrectThe neck extends.(reduced)IncorrectThe neck motion is > 90 degrees.NeckThe range of motion should be more than 90°. Motion less than 80° may triple the riskof a poor view at laryngoscopy. Airway Evaluation SummaryBecause of the reduced mentum-hyoid distance, it may be difficult tovisualize the larynx with traditional direct laryngoscopy. There areother options, including other blades and techniques that do notrequire a direct line-of-sight, which are beyond the scope of this site.Perhaps the most conservative method of securing the airway of apatient who is anticipated to have a "difficult airway" is with awakefiberoptic intubation. This technique requires substantial skill, butallows intubation in an awake, spontaneously breathing patient. Thetrachea is identified with a flexible fiberscope, and then theendotracheal tube is advanced over the fiberscope like a stylet. Suchmohammad reza rajabi Page 18 4/3/2012
  • 19. a procedure requires blockade of the sensory innervation to theairway, and blunting of the gag reflex. Innervation of the Upper AirwayAwake fiberoptic intubation requires topical anesthesia for patientcomfort, as well as to blunt the gag reflex that would preventsuccessful intubation of the trachea.Several nerves are involved in the sensation of the upper airway:  Anterior 2/3 of the tongue - Trigeminal nerve (V).  Posterior 1/3 of tongue to epiglottis - Glossopharyngeal nerve (IX; afferent limb of gag reflex).  Epiglottis to vocal cords - Internal branch of Superior Laryngeal Nerve (Vagus, X)mohammad reza rajabi Page 19 4/3/2012
  • 20.  Trachea below vocal cords - Recurrent Laryngeal Nerve (Vagus, X)MOTOR INNERVATIONMotor innervation to the larynx is provided by the Vagus Nerve, butrecall there are two branches involved. The Recurrent LaryngealNerve innervates all the muscles of the larynx EXCEPT thecricothyroid muscle, which is innervated by the External Branch ofthe Superior Laryngeal Nerve. Because the function of thecricothyroid muscle is to stretch and tense the vocal cords,unopposed action of the cricothyroid, as may occur with bilateraldestruction of the recurrent laryngeal nerves, would lead to stridor,respiratory distress and possibly airway obstruction.GAG REFLEXSo the sensory, afferent limb of the gag reflex is theglossopharyngeal nerve (IX), while the motor, efferent limb is theVagus (X).Its not much of a mnemonic, but I remember this as a variant ofTGIF: "Thank God its Recurrent" I know, its lame, perhaps justlame enough to be memorable! Airway BlocksTopical application of local anesthetics is usually sufficient for thetongue and oro/nasopharynx, though glossopharyngeal blocks areperformed occasionally. Blunting of the gag reflex requiresTranstracheal (really translaryngeal) with or without bilateralSuperior Laryngeal Nerve blocks as shown below.mohammad reza rajabi Page 20 4/3/2012
  • 21. The superior laryngeal nerves are blocked by deposition of 1%lidocaine near where the nerves penetrate the thyrohyoidmembrane. The transtracheal block is accomplished with 4%lidocaine injected directly into the tracheal lumen. Often this blockalone, coupled with nebulized or atomized lidocaine is sufficient forawake intubation.mohammad reza rajabi Page 21 4/3/2012
  • 22. Airway Structures The right panel displays images seen during fiberoptic bronchoscopy. The corresponding level on CT is displayed on the middle panel. Place the cursor over structures to learn their identity.mohammad reza rajabi Page 22 4/3/2012
  • 23. mohammad reza rajabi Page 23 4/3/2012
  • 24. Review of Airway InnervationLets review the innervation of the upper airway:mohammad reza rajabi Page 24 4/3/2012
  • 25. Purple Facial (VII) Trigeminal (V) Glossopharyngeal (IX) Vagus (X)(VII)NoThe Facial Nerve supplies only taste to the tongue.(V)YesThe maxillary branch (V2) supplies the nasal cavity and palate, whilethe mandibular branch (V3) supplies the anterior 2/3 of the tongue.(IX)IncorrectThe glossopharyngeal nerve supplies sensation to the posterior 1/3of the tongue and its overlying structures including the soft palate.(X)NoThe vagus innervates the airway further distal. Green Facial (VII) Trigeminal (V) Glossopharyngeal (IX) Vagus (X)(VII)NoThe Facial Nerve supplies only taste to the tongue.(IX)YesThe glossopharyngeal nerve supplies sensation to the posterior 1/3of the tongue and its overlying structures including the soft palate.(V)NoThe maxillary branch (V2) supplies the nasal cavity and palate, whilethe mandibular branch (V3) supplies the anterior 2/3 of the tongue.(X)NoThe vagus innervates the airway further distal.mohammad reza rajabi Page 25 4/3/2012
  • 26. Blue Facial (VII) Trigeminal (V) Glossopharyngeal (IX) Vagus (X)(VII)NoThe Facial Nerve supplies only taste to the tongue.(IX)NoThe glossopharyngeal nerve supplies sensation to the posterior 1/3of the tongue and its overlying structures including the soft palate.(V)NoThe maxillary branch (V2) supplies the nasal cavity and palate, whilethe mandibular branch (V3) supplies the anterior 2/3 of the tongue. (x)Yes, but which branch Internal branch of superior laryngeal External branch of superior laryngeal Recurrent laryngeal(YesThe Internal Branch of the Superior Laryngeal Nerve providessensory innervation to the mucous membrane from the epiglottis toand including the vocal cords.IncorrectThe External Branch of the Superior Laryngeal nerve provides motorinnervation to the cricothyroid muscle only.IncorrectThe Recurrent Laryngeal Nerve supplies sensory innervation to thetrachea below the vocal cords, as well as motor innervation to all theintrinsic muscles of the larynx except the cricothyroid muscle.. )mohammad reza rajabi Page 26 4/3/2012
  • 27. Red Facial (VII) Trigeminal (V) Glossopharyngeal (IX) Vagus (X)(VII)NoThe Facial Nerve supplies only taste to the tongue.(IX)NoThe glossopharyngeal nerve supplies sensation to the posterior 1/3of the tongue and its overlying structures including the soft palate.(V)NoThe maxillary branch (V2) supplies the nasal cavity and palate, whilethe mandibular branch (V3) supplies the anterior 2/3 of the tongue. (x)Yes, but which branch Internal branch of superior laryngeal External branch of superior laryngeal Recurrent laryngeal(IncorrectThe Internal Branch of the Superior Laryngeal Nerve providessensory innervation to the mucous membrane from the epiglottis toand including the vocal cords.IncorrectThe External Branch of the Superior Laryngeal nerve provides motorinnervation to the cricothyroid muscle only.YesThe Recurrent Laryngeal Nerve supplies sensory innervation to thetrachea below the vocal cords, as well as motor innervation to all theintrinsic muscles of the larynx except the cricothyroid muscle..)mohammad reza rajabi Page 27 4/3/2012
  • 28. Case 3: Spine EvaluationA previously healthy 40-year-old male presents with an open femurfracture from a Motor Vehicle Accident (MVA) that needs to berepaired under general anesthesia. He is currently on a backboardwith a cervical collar in place and is hemodynamically stable.Examination of this patients airway is complicated by the presenceof the cervical collar, which both inhibits mouth opening and bydefinition prevents neck extension. As you have seen above, neckextension is required for direct laryngoscopy.So what shall we do? Remove the neck collar and intubate as usual. Intubate with a technique that does not require neck movement. Avoid general anesthesia and perform a regional block for theprocedure. Perform studies to "clear" the cervical spine.First a basic review of the anatomy is helpful.Recall that the cervical spine consists of 7 vertebrae, the first two ofwhich are highly specialized.(Should this patient have an unstable cervical spine, the movementresulting from laryngoscopy could permanently damage the spinalcord, likely resulting in quadriplegia.)(There are numerous techniques (retrograde intubation,…) purportedto involve less cervical spine motion, each of which requiressubstantial skill and experience. These should only be attempted byexperienced practitioners. Some advocate "in-line stabilization"where a second person attempts to hold the cervical spine still whilethe primary person attempts direct laryngoscopy. This techniquemakes intubation more difficult, and is inadequate for stabilization.)mohammad reza rajabi Page 28 4/3/2012
  • 29. (While an attractive option, many would argue that anytime aregional anesthetic is planned, immediate endotracheal intubationmust be possible. Complications may occur during the regional block,or it may be inadequate for the operation, or wear off before thesurgeons are done. Therefore, inability to emergently intubate apatient is a relative contraindication to regional anesthesia andshould be considered in this patient with a possible unstable neck.)(Great idea!) Cervical Spine Anatomy-AtlasC1: The Atlas is a ring that interacts with the skull base above andC2 shown on next page. It is unique in that it lacks a vertebral bodyand spinous process. The articulation of C1 with the occiput is verytight, providing little of the flexion of the cervical spine and onlyabout 20 degrees of extension.mohammad reza rajabi Page 29 4/3/2012
  • 30. Cervical Spine Anatomy-AxisC2: The Axis has an unusual thumb-like extension of its vertebralbody that passes through the arch of C1. This process is called thedens or odontoid. The odontoid process is normally held very tightlyagainst the anterior arch of C1 by the transverse ligament.Meanwhile the spinal cord travels behind the odontoid within thearch of C1.mohammad reza rajabi Page 30 4/3/2012
  • 31. Atlanto Axial JointThis atlanto-axial joint provides the majority of the rotational motionof the cervical spine. Meanwhile flexion and extension are primarilyaccomplished at C2 and below, and particularly between C4 and C6. Neck Movement with DLWhat happens to the neck during direct laryngoscopy andintubation?As you have seen, the sniffing position involves neck flexion in thelower cervical spine with extension superiorly. In the process ofdirect laryngoscopy this motion is accentuated. As the laryngoscopeis lifted upward, the occiput is extended primarily at the atlanto-occipital joint (occiput-C1), while flexion occurs at C2-3 and below.Therefore, any intervention that impedes this flexion and extensionwill make visualization of the glottis more difficult. In someone witha cervical fusion up to the occiput it is pretty much impossible toperform direct laryngoscopy. Similarly, a patient with externalstabilization such as a c-collar in this case will (SHOULD) have neckmovement reduced sufficient to make visualization difficult if notimpossible.mohammad reza rajabi Page 31 4/3/2012
  • 32. Clearing the C-SpineHow does one rule out damage to the cervical spine?At present history is our greatest ally. If the healthy patient has nohistory of neck problems and no symptoms on maximal flexion andextension, they are unlikely to have cervical spine disease.On the other hand there are many patients whose cervical spineSHOULD be radiographically evaluated pre-operatively includingcertain trauma patients, as well as those with disease states thataffect the cervical spine including rheumatoid arthritis and DownsSyndrome. These diseases may affect the transverse ligament andthus the stability at the atlanto-axial joint. Nexus CriteriaWhich trauma patients require cervical spine films prior to surgery orintubation?There is a set of criteria identified by the National Emergency X-Radiography Utilization Study (NEXUS) that attempt to identifypatients with a low probability of injury, thereby reducing thenumber of negative cervical spine radiographs taken.The criteria include No midline cervical tenderness No focal neurologic deficit Normal alertness No intoxication No painful, distracting injury that might make them ignore theirneck painFor those patients whose cervical spine is not cleared, theanesthesiologist must consider the risks of cervical spine damagethat can be worsened through direct laryngoscopy, versus the risk ofalternative techniques that may minimize neck motion, includingawake fiberoptic intubation. A description of these alternatetechniques is beyond the scope of this site at present.mohammad reza rajabi Page 32 4/3/2012
  • 33. Spine Film For the current case the following film is obtained. Patients Film Normal for Comparisonmohammad reza rajabi Page 33 4/3/2012
  • 34. ExplanationNote the large step-off between C6 and C7. This subluxation causesentrapment of the spinal cord and damage.Therefore this patient requires an intubation technique with minimalneck motion and awake positioning,as well as some externalstabilization or operative intervention to prevent damage to thespinal cord at the neck.mohammad reza rajabi Page 34 4/3/2012
  • 35. C-Spine ReviewSo which patients are at higher risk for neck injury duringintubation? Trauma patients Yes No (yes)Correct!They may have trauma to the cervical spine as well. (no)Incorrect!They may have trauma to the cervical spine as well. Rheumatoid arthritis patients Yes No (yes)Correct!Approximately 30% of patients with severe disease will have someinstability at C1-C2. All should have periodic flexion or extensionxrays, particularly prior to surgery. (no)Incorrect!Approximately 30% of patients with severe disease will have someinstability at C1-C2. All should have periodic flexion or extensionxrays, particularly prior to surgery. Downs Syndrome patients Yes No (yes)Correct!About 15% of these patients have laxity in the transverse ligamentthat holds the odontoid against the anterior arch of C1. Xrays arealso recommended in these patients prior to anticipated neckmanipulation including laryngoscopy.mohammad reza rajabi Page 35 4/3/2012
  • 36. (no)Incorrect!About 15% of these patients have laxity in the transverse ligamentthat holds the odontoid against the anterior arch of C1. Xrays arealso recommended in these patients prior to anticipated neckmanipulation including laryngoscopy. Osteoarthritic patients Yes No (yes)IncorrectThey are not at higher risk. (no)CorrectThey are not at higher risk Patient with a prior cervical spine fusion Yes No(yes)IncorrectAssuming the repair is stable and there is no further disease there islittle risk of damage. Such patients may be difficult to intubate,though, if their mobility is significantly limited.(no)CorrectAssuming the repair is stable and there is no further disease there islittle risk of damage. Such patients may be difficult to intubate,though, if their mobility is significantly limited.mohammad reza rajabi Page 36 4/3/2012
  • 37. Airway References Cricoid PressureVanner RG, Asai T. Safe use of cricoid pressure. Anaesthesia 1999: 54: 1-3. A review of literature with recommendations.Sellick BA. Cricoid pressure to control regurgitation of stomach contents during induction of anaesthesia. Lancet 1961; 2: 404-6. The original description. Views and GradesMallampati SR, Gatt SP, et al. A clinical sign to predict difficult tracheal intubation: a prospective study. Can Anaesth Soc J 1985;32(4):429-434. The original paper describing the classification system, but only 3 grades (III and IV combined).Samsoon GLT and Young JRB. Difficult tracheal intubation: a retrospective study. Anaesthesia 1987;42:487-490. Describes the addition of Mallampati class 4Cormack RS and Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia 1984;39:1105-1111. Describes the laryngoscopy grades and correlates with difficult intubation. Also proposes a technique of attempting to intubate while intentionally achieving a suboptimal (Class III) view.Studies of Predictive Indices There are many studies, some which counter others. One difficulty is defining a difficult airway. Most use a Cormack-Lehane laryngoscopy grade of III-IV. Some investigate specific radiographic measurements that are impractical in daily clinical practice. Below are a few useful references:El-Ganzouri AR, McCarthy RJ, et al. Preoperative airway assessment: Predictive value of a multivariate risk index. Anesth Analg 1996;82:1197-1204. A logistic regression comparing examination tests and developing a risk index.Chou HC, Wu TL, et al. Mandibulohyoid distance in difficult laryngoscopy. Br J Anaesth 1993; 71:335-339. A single article sighting this distance as an important factor in an analysis of only 11 patients.Frerk CM. Predicting difficult intubation. Anaesthesia 1991;46:1005-1008. A study suggesting that a Mallampati Class III or IV with thyromental distance of <7cm is sensitive and specific for difficult intubation (laryngoscopy grade 3 or 4). C-Spine Evaluation mohammad reza rajabi Page 37 4/3/2012
  • 38. Hoffman JR, Mower WR, et al. Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. N Engl J Med 2000;343:94- 99. Application of the NEXUS criteria. mohammad reza rajabi Page 38 4/3/2012