Airway assessment between adult & paediatrics

Airway assessment between adult & paediatrics,
anaesthesia
airway
DAS , AIDAA

1. Difference between Adult And Paediatric Airway And Difficult Airway Assessment DR. ZIKRULLAH

2. DIFFERENCE BETWEEN PAEDIATRIC AND ADULT UPPER AIRWAY ?

3. Large head Large tongue in small oral cavity Mandibular angle 140 Narrow, floppy, relatively long and U-shaped epiglottis

4. Angled vocal cords More rostral Larynx at C3-C4 Funneled shaped larynx-narrowest part of pediatric airway is cricoid cartilage

5. Differently shaped epiglottis

6. What are the anaesthetic implication of large head?

7. HEAD :  Children have a large head , short neck and a prominent occiput .  So the head flexes forward onto the chest when the infant is lying supine with its head in the midline .

8. Extreme extension can also obstruct the airway, so a midposition of the head with slight extension is preferred for airway maintenance. This is accomplished by placing a small roll at the base of the neck and shoulders

9. Airway positioning for children <2yrs

10. NOSE & NASOPHARYNX : Neonates and young infants are obligate nose breathers until about 3 months of age Their narrow nasal passages are easily blocked by secretions and may be damaged by a nasogastric tube or a nasally placed endotracheal tube.

11. 50% of airway resistance is from the nasal passages.  The horizontal positioning of the eustachian tube places the infant at greater risk for ear infections from food or liquid that refluxes upward into the nasopharynx . They have prominent adenoids and tonsils.

12. OROPHARYNX : The tongue is relatively large.  The soft palate and epiglottis are in contact at rest, providing an additional valve at the back of the oral cavity.

13. What is the level of glottis in pediatric patient?

14. GLOTTIS : In the normal adult, the glottis is at the level of C5. In the fullterm infant, the glottis is at the level of C4. And in the premature infant, it is at the level of C3.

15. Children Adults

16. ANESTHETIC IMPLICATIONS : The combination of a large tongue and a relatively high glottis means that on laryngoscopic examination it is more difficult to establish a line of vision between the mouth and larynx; there is relatively more tissue in less distance. Therefore, the infant's larynx appears to be anterior.

17. When combined with the anterior-slanting vocal cords, the result is a more difficult laryngoscopic examination and intubation. Application of cricoid pressure by the anesthesiologist or an assistant improves visualization of the neonate's larynx.

18. What are the differences in adult and pediatric epiglottis?

19. EPIGLOTTIS : The epiglottis is long, stiff and U-shaped. It flops posteriorly . In newborn In adult

20.   ANESTHETIC IMPLICATIONS : Straight Magill blades are useful in neonates and infants. A size 0 blade is best in babies <4 kg. A curved blade is usually easier once the child is 6-10 kg.

21. Which is the narrowest part of airway in infants?

22. LARYNX :   The airway is narrowest at the level of the cricoid cartilage. Here, pseudo-stratified, ciliated epithelium is loosely bound to the underlying areolar tissue.

23. Narrowest point = cricoid cartilage in the child

24. Trauma to the airway easily results in oedema . One millimetre of oedema can narrow a baby’s airway by 60% . It is suggested that a leak be present around the endotracheal tube to prevent trauma resulting in subglottic oedema and subsequent post- extubation stridor . 

25. What is the effect of edema in airway?

26. Effect of Edema Poiseuille’s law If radius is halved , resistance increases 16fold R = 8 n l  r 4

27. AIRWAY EDEMA OF 1 MM MAY REDUCE THE AIRWAY BY 64% & THAT OF AN ADULT BY 35%

28. Because the airway is cone shaped, with the narrowest point at the cricoid cartilage, an uncuffed tube is adequate to seal the trachea. Using an uncuffed tube allows us to maximize the inner diameter of the tube, decreasing airway resistance and turbulence .

29. What is the shape and size of trachea in pediatric age groupe ?

30. TRACHEA :  The trachea is 4-5 cm long and funnel shaped.

31. In the adults, the airway from the vocal cords down the trachea is of equal dimensions and if the endotracheal tube passes comfortably through the vocal cords, it will not be tight within the cricoid cartilage.

32. However, since the neonate's laryngeal structures resemble a funnel, even though the endotracheal tube may pass through the vocal cords, which are at the midpoint of the funnel, the endotracheal tube may be tight within the cricoid ring.

33. The tracheal bifurcation is at T2 rather than at T4 as in the adult. Hence endobronchial intubation occurs easiIy . This is especially so using preformed endotracheal tubes with the head flexed.

34. Conversely, extension of the head may lead to accidental extubation . After intubation or a change in the patient’s position, the chest should be auscultated to check that the tube has, been placed correctly.

35. How the pediatric lung is different from the adult lung?

36.   LUNGS : The neonate and infant have limited respiratory reserve.   Horizontal ribs prevent the ‘bucket handle’ action seen in adult breathing and limit an increase in tidal volume.

37. Ventilation is primarily diaphragmatic. Bulky abdominal organs or a stomach filled with gases from poor bag mask ventilation can impinge on the contents of the chest and splint the diaphragm. 

38. The chest wall is significantly more compliant than that of an adult. Subsequently, the functional residual capacity (FRC) is relatively low. FRC decreases with apnea and anesthesia causing lung collapse. 

39. Minute ventilation is rate dependant as there is little means to increase tidal volume.  The ratio of minute ventilation to FRC is 5:1 in the neonate, whereas in adults it is 1.5:1 .

40. The clinical implication of the high ratio of minute ventilation to FRC is that there is a much more rapid induction of inhalational anesthesia, as well as more rapid awakening. The oxygen consumption of the infant is 7 to 9 mL /kg/min, whereas in the adult it is 3 mL /kg/min .

41. Therefore, varying degrees of airway obstruction have more impact on oxygen delivery and reserve in the neonate and in the infant in the mature state.

42.   The closing volume is larger than the FRC until 6-8 years of age. This causes an increased tendency for airway closure at end expiration.

43. Thus, neonates and infants generally need IPPV during anesthesia and would benefit from a higher respiratory rate and the use of PEEP. CPAP during spontaneous ventilation improves oxygenation and decreases the work of breathing. 

44.   Work of respiration may be 15% of oxygen consumption.  Muscles of ventilation are easily subject to fatigue due to low percentage of Type I muscle fibers in the diaphragm. This number increases to the adult level over the first year of life. 

45. Apneas are significant if they last longer than 15 seconds and are associated with desaturation or bradycardia .

46. What are the normal respiratory value in adult and infant?

47. Comparison of Normal Respiratory Values in Infants and Adults PARAMETER INFANT ADULT Respiratory frequency ( per minute ) 30 – 50 12 – 16 Tidal volume ( mL /kg) 7 7 Dead space ( mL /kg) 2.0 -2.5 2.2 Alveolar ventilation ( mL /kg/min) 100 – 150 60 Functional residual capacity ( mL /kg) 27 – 30 30 Oxygen consumption ( mL /kg/min) 7 - 9 3 Numbers of alveoli ( million ) 20-50 300

48. Essential Components of Airway Assessment - History - Examination - Specific tests & indices. Specific anomalies / pathologies affecting the upper & lower airway management.

49. Assessment of difficult Airway

50. Anatomically, airway is a passage through which air/gas passes during respiration. It can be divided into :- upper airway lower airway

51. UPPER AIRWAY

52. LOWER AIRWAY

53. INDICATION FOR AIRWAY INTERVENTION ?

54. Direct trauma to airway/ obstruction. Severely wounded (e.g. profound bleeding, head injury, comatose, etc.) Respiratory failure secondary to blast or inhalational injury, or exposure to chemical agents. Controlled airway during GA & surgery.

55. How will you define a difficult airway ?

56. ASA definition of difficult airway : “The clinical situation in which a conventionally trained anaesthetist experiences difficulty with mask ventilation, difficulty with tracheal intubation or both.”

57. What is the definition of difficult mask ventilation?

58. “It is not possible for the unassisted anaesthesiologist to maintain oxygen saturation > 90% using 100% oxygen and positive pressure mask ventilation in a patient whose oxygen saturation was > 90% before anaesthetic intervention.”

59. What is the definition of difficult laryngoscopy ?

60. “It is not possible to visualize any portion of the vocal cords with conventional laryngoscope.”

61. How would you define a difficult endotracheal intubation?

62. “ Proper insertion of the tracheal tube with conventional laryngoscopy requires >3 attempts or > 10 minutes.”

63. According to Canadian Airway Focus Group difficult intubation is defined as- An experienced laryngoscopist , using direct laryngoscopy , requires: >2 attempts with the same blade or a change in the blade or an adjunct to direct laryngoscope or use of an alternative device or technique following failed intubation with direct laryngoscopy .

64. Importance of airway assessment ?

65. To diagnose the potential for difficult airway for : Optimal patient preparation Proper selection of equipments and techniques Participation of personnel experienced in the difficult airway management.

66. Four pillars of airway management ?

67. 1) Mask Ventilation. 2) Tracheal intubation. 3) Placement of supraglottic device. 4) Creation of a surgical airway [Surgical Tracheostomy/PCT]. Any one or a combination of the above may be required.

68. What are essential components of airway assessment ?

69. History taking. General examination of the patient. Specific tests/indices to predict difficult airway.

70. I :History Documented history of difficult airway: - previous anaesthesia records, - previous surgery, - burn, - trauma or tumor in/around the oral cavity, - concurrent disease.

71. Factors predisposing difficult airway: Congenital: pierre Robin syndrome Treacher collins syndrome Downs syndrome Kipple Feil syndrome Goiter

72. Acquired: Infection- croup, abcess , ludwigs angina Sub mucus oral fibrosis Arthritis- RA, AS Benign tumor - cystic hygroma , lipoma , adenoma Malignant tumor

73. Facial injury Cervical spine injury Laryngeal or tracheal injury Obesity Acromegaly

74. II .General examination Should include recognition of the anatomical factors that cause difficult laryngoscopy and intubation. The airway may be assessed for difficult airway using :- -Individual indices. -Group indices(with and without scoring).

75. Components of Physical Examination of the Airway ?

76. Visual inspection of the face and neck • Assessment of mouth opening • Evaluation of oropharyngeal anatomy and dentition • Assessment of neck range of motion (ability of the patient to assume the sniffing position) • Assessment of the submandibular space.

77. III. Airway assessment tests/predictors Categorized as per the four pillars of Airway Management: Mask Ventilation Laryngoscopy & intubation Placement of supraglottic device Creation of a surgical airway[ SurgicalTracheostomy /PCT]

78. Predictors of difficult mask ventilation ?

79. INDIVIDUAL INDICES : presence of Beard Obesity Abnormality of teeth Elderly patient Snorers Hair bun Jewellery & facial piercing GROUP INDICES :

80. INDIVIDUAL INDICES : Beard: difficulty in creating an effective seal by mask leading to loss of ventilated volume Obesity: ( BMI > 26 kg/m 2 ) larger force during ventilation Decreased FRC Prone to quick desaturation.

81. 3 . No teeth/ abnormality of teeth: - Face tends to “cave in”, offers poor fit for BMV. - Consider leaving dentures in for BMV & remove for intubation 4. Elderly Age > 55 yrs. 5. Snorers

82. 6 . Hair bun: - prevents extension of atlanto -occipital joint. Advisable to undo the bun prior to positioning of the head & neck . 7. Jewelry & facial piercing

83. GROUP INDICES :

84. F – O – A – M F acial hairs, deformities such as burns, scarring, growth, emaciated face preclude adequate fit of face mask. O besity ( BMI > 26 ), O bstructed breathing (H/O of snoring) A ged > 60 years , Absence of teeth M ovement restriction of head and neck (Extension: Flexion) inability to slide the lower jaw incisors Presence of any 2 or more of these should alert the anaesthesiologist for difficult BMV.

85. Predictors of difficult laryngoscopy and tracheal intubation ?

86. INDIVIDUAL INDICES : Physical examination indices Radiological indices Advanced indices GROUP INDICES : wilson’s scoring. Benumof’s 11 parameter Arne’s simplified score. Rocke et al grading Rapid airway assessment

87. I : Assessment of cervical and a-o joint function Direct assessment - Flexion of the neck on the chest by 25-35 degrees is possible - Extension of the a-o joint by 85 degrees is possible( magill’s /sniffing position) ( 2/3 rd or complete reduction of extension at AO joint is a clear pointer to difficult rigid laryngoscopy.) 89

88. What is Delilkan’s test ?

89. Delilkan’s test: Assesses movement of the occiput on the atlas during extension. Assessed by asking the patient to look at the ceiling without raising the eyebrows.

90. Indirect Assessment PRAYER SIGN Esp. in long term juvenile diabetic pt. May indirectly predict the possibility of cervical spine involvement & limited a-o movement. PALM PRINT TEST

91. What is Palm Print test ?

92. Developed to assess difficult laryngoscopy in diabetic patients. The palm and fingers of the dominant hand of the patient is painted with black writing ink using a brush. The patient then presses the hand firmly against a white sheet of paper on a hard surface.

93. Scoring is done as:- Grade 0 - All phalangeal areas visible. Grade 1 - Deficiency in the inter-phalangeal areas of 4th and/or 5 th digit. Grade2 - Deficiency in the inter-phalangeal areas of 2nd to 5 th digit. Grade 3 - Only the tips of digits seen.

94. II: Assessment of TMJ function Rotation of condyles in the synovial cavity Forward displacement of condyles Rotation is responsible for the initial 2-3 cm of mouth opening and displacement for the later 2-3cm mouth opening. Suggests subluxation of the lower jaw.

95. III: Assessment of mandibular space ? a) Thyromental distance (thyroid notch & mentum in full extension)…. Patil’s test b) Hyomental distance ( mentum and hyoid bone)

96. a)Thyromental distance :- > 6.5 cm : no problem with laryngoscopy & intubation 6- 6.5 cm : difficult but possible <6 cm : may be impossible Tells the probability of alignment of pharyngeal &laryngeal axes and space for tongue.

97. b) Hyomental distance:- Distance between the mentum and hyoid bone. GRADE I: > 6 cm GRADE II: 4.0- 6.0 cm GRADE III: < 4.0 cm Grade III is associated with impossible laryngoscopy and intubation

98. Test for assessing the adequacy of the oropharynx ?

99. a)Modified Mallampatti Grading Indicates space to accommodate laryngoscope &ETT b) Narrowness of the palate Narrow and arched palate offers little space for laryngoscopy & intubation.

100. Modified Mallampati Grading ?

101. As per Samsoon & Young’s modification, GRADE I : Faucial pillars, uvula,soft and hard palate visible GRADE II : uvula, soft and hard palate visible GRADE III : base of uvula or none,soft and hard palate visible GRADE IV : only hard palate visible Grade I & II is associated with easy and grade III & IV with difficult laryngoscopic view.

102. Assessment of quality of glottic view during laryngoscopy ?

103. Three tests are available: Indirect mirror laryngoscopic view Direct laryngoscopic or awake look POGO scoring.

104. Indirect mirror laryngoscopic view Classification: Complete vocal cord visible Posterior commissure visible Epiglottis visible No glottic structure visible

105. Cormack and lehane grading ?

106. GRADE I: visualisation of the entire vocal cords GRADE II : visualisation of the posterior part of laryngeal aperture IIa : posterior part of vocal cord only IIb : arytenoids only GRADE III: visualisation of epiglottis IIIa : epiglottis liftable IIIb : epiglottis adherent/only tip visible GRADE IV : no glottic structure seen

107. What Is POGO scoring ?

108. Percentage of glottic opening seen while directly visualizing through the laryngoscope. Entire glottis visualized- 100% score No glottic stucture is visible- 0% score Only lower 1/3 rd of vocal cords and arytenoids visible- 33% score is given

109. STERNO-MENTAL DISTANCE WITH MOUTH CLOSED AND HEAD IN FULL EXTENSION , <12.5 cm -difficult laryngoscopic intubation Sensitivity of 0.82 & specificity of 0.89 Single best predictor of difficult laryngoscopy and intubation.

110. Modified measurement of sternomental distance: Distance from sternal notch to tip of chin with the patient in both neutral and maximally extended position. Increase of >5 cm : easy laryngoscopy Increase of <5 cm: difficult laryngoscopy

111. Group indices ?

112. Some of the important group indices far airway assessment WILSON’S SCORING SYSTEM BENUMOF’S 11 PARAMETER ANALYSIS ROCKE’S ASSESSMENT OF OBSTETRICS PATIENT RAPID AIRWAY ASSEESMENT(1-2-3 )

113. Wilson Scoring System ?

114. PARAMETER 1 2 Weight(kg) <90 90-110 >110 Head &Neck Movement >90 =90 <90 Jaw Movement (Int. insc . gap) >5 Cm =5 Cm <5cm slide mandible beyond maxilla >0 =0 <0 Receding Mandible None Moderate Severe Buck Teeth None Moderate Severe

115. Score - < 5 Easy Laryngoscopy 6-7 Moderate Difficulty 8-10 Severe difficulty during conventional laryngoscopy

116. Benumof’s 11 parameter analysis ?

117. C: Rocke et al (1992) Combined Mallampati Grading with factors such as Obesity Short neck Abnormality of the teeth Receding mandible facial oedema showed significant correlation b/w classification of airway and laryngoscopic grade

118. ≥ 2 risk factors, if present, are multiplied to give actual risk probability

119. Rapid airway assessment ?

120. To rapidly assess : TMJ function, mouth opening, and mandibular space 1-finger test 2-finger test 3- finger test This can be done in < 15 seconds.

121. Rapid airway assessment test tells us regarding the space in front of the larynx for the tongue to be compressed . Ease with which the pharyngeal and laryngeal axis will fall in line when the a-o joint is extended.

122. 2. Radiological indices a) Ratio of the effective mandibular length to its posterior depth < 3.6 b)Distance between occiput and the spinous process of C1 < 5 mm c)Posterior depth of mandible > 2.5cm d)Rostral mandibular angle and caudal hyoid bone. Points of measurements from skeletal films ; 1 = Effective mandibular length, 2 = Posterior mandibular depth, 3 = Anterior mandibular depth, 4 = Atlanto -occipital gap, 5 = C1 – C2 gap

123. Advanced indices for predicting difficult airway ?

124. a)Flow volume loops: Help in differentiating obstruction in small airways from the large airways and whether the obstruction is intra or extra thoracic. b) Acoustic response measurement c) MRI

125. b ) Acoustic response measurement : Erzi et al (2003) - Quantified the anterior neck soft tissue by USG . - Useful esp in obese pts. Distance from the skin to the anterior aspect of trachea is measured at 3 levels: zone1 : vocal cords zone2 : thyroid isthmus zone 3: suprasternal notch. - Amount of soft tissue at each zone is calculated by averaging the central axis of neck & 15mm to right & left.

126. Thickness > 25 mm in zone 1 , or Average of all 3 zones > 28 mm clear pointer to difficult laryngoscopy & intubation . c) MRI Sagittal MRI to diagnose complex airway disorders, not ascertainable by the more routinely employed tests.

127. What is LEMON law ?

128. GIVEN BY WALLS IN 2000 : L …Look for features suggestive of difficulty E Examine the anatomy M .. Mallampati grade O Obstruction- location, type, progression N Neck mobility

129. L ook for the anatomical features suggestive of difficulty Short neck Edentulous patient Obesity Buck teet Big tongue Facial trauma Facial/oral swelling tumour

130. E xamine the airway anatomy Assess the oral opening -should accommodate 3 fingers Assess the ability of the mandible to accommodate the tongue- 3 fingers b/w hyoid and mentum Externally assess for high larynx-should be able to accommodate 2 fingers between top of thyroid cartilage and the floor of the mouth

131. 3-3-2 Rule?

132. M allampati grading : 91.2% had MP grade 1 6.3% had MP grade 2 2.1% had MP grade 3 0.4% had MP grade 4 Nearly 2.5% may have moderate to difficult airway.

133. O bstruction Location of the obstruction ( above or below the glottis). Is the obstruction fixed( tumor) or mobile. How rapid is the obstruction progressing.

134. N eck mobility Can the pt. flex his neck (chin on the chest).. or can he extend his head at the atlanto -axial joint (look at the ceiling). Cervical spine immobilization is an obvious difficulty.

135. What are 4 D’s of difficult airway assessment ?

136. The following  Four D's  suggesting a difficult airway : D entition (prominent upper incisors, receding chin) D istortion (edema, blood, vomits, tumor, infection) D isproportion (short chin-to-larynx distance, bull neck, large tongue, small mouth) D ysmobility (TMJ and cervical spine)

137. What are magboul’s 4 M’s for assessing difficult airway ?

138. M allampati M easurement M ovement M alformation of skull, teeth.

139. What is upper lip bite test ?

140. Tests the range & freedom of mandibular movement & the architecture of teeth (khan et al in 2002) Class I : lower incisors can bite the upper lip above the level of vermilion line Class II : lower incisors can bite the upper lip below the level of vermillion line Class III : lower incisors cannot bite the upper lip. Class III are expected to have cormack and lehane grade III and IV laryngoscopic view of the larynx.

141. Prediction of Difficult placement of Supraglottic Airways ?

142. R : Restricted mouth opening (<2 cm) O : Obstruction of the upper airway mass, foreign body, edema D : Disrupted upper airway, trauma, ingestion of caustics. S : Stiff lung or poor thoracic compliance Presence of any of them alerts the attending anaesthesiologist for difficult supraglottic device placement and / or poor ventilation R-O-D-S

143. Prediction of Difficult Surgical Airway ?

144. B : Bleeding tendency (but not restricted to) inherent or as a result of anticoagulants. A : Agitated patient N : Neck scarring or neck flexion deformity G : Growth or vascular abnormalities in the region of surgical airway Presence of any of these BANG factors may predict difficult in performing the surgical airway. B – A – N – G

145. Anomaly/pathology that affect upper airway Facial anomaly: maxillary hypoplasia eg . Apert syndrome,crouzon disease mandibular hypoplasia eg.pierre robin syndrome, treacher collin syndrome, goldenhar syndrome mandibular hyperplasia eg . acromegaly

146. TMJ pathology Ankylosis or reduced movement Anomalies of mouth and tongue Microstomia Swelling of the tongue Tumours of the mouth or the tongue macroglossia

147. Pathology of the pharynx Hypertrophic tonsils and adenoid Tumours and abscesses Retropharyngeal and/or parapharyngeal abscess

148. Pathology of the larynx Supraglottic : Epiglotitis Glottis :Laryngomalacia , granuloma, FB, pappilomas Infraglottic : congenital stenosis, inflammatory oedema

149. A simple and rapid way of assessing airway in children developed by LANE. COPUR SCALE ?

150. COPUR : C- Chin Normal - 1 Small, moderately hypoplastic - 2 Markedly recessive - 3 Extremely hypoplastic - 4 O – Mouth opening >40 mm - 1 20 – 40 mm - 2 10 – 20 mm - 3 <10 mm - 4

151. P – Previous Intubation Easy previous attempt - 1 No prev. attempt.no h/o OSA - 2 OSA, prev. h/o diff. intubation - 3 Unable to lie supine, h/o tracheostomy - 4 U – Uvula Whole visible - 1 Partially visible - 2 Only soft palate visible - 3 Soft palate not visible - 4

152. R – Range of neck movement >120 - 1 60 – 120 - 2 30 – 60 - 3 <30 - 4

153. R – Range of neck movement >120 - 1 60 – 120 - 2 30 – 60 - 3 <30 - 4

154. PREDICTION POINTS : 5 – 7 : easy , normal intubation 8 – 10 : laryngeal pressure may help 12 : increased difficulty, fibreoptic may be preferred 14 : difficult intubation, fibreoptic/ other advanced technique should be preferred 16 : dangerous airway , awake intubation/ tracheostomy

155. Conclusion : No single airway test can provide a high index of sensitivity and specificity for prediction of difficult airway. Therefore it has to be a combination of multiple tests. Thus, anaesthesiologists must always be prepared with a variety of preformulated and practiced plans for airway management in the event of an unanticipated difficult airway.

156. Thank you…