airway management in children - medIND

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However, rapid recovery is one of the features that can be of immense advantage in a child ..... neck, large tongue and long floppy epiglottis. Transtracheal jet ... Only limited data are available of their use in paediatric age group hence PDC is ...

ISSUE2005; : AIRWAY 300 Indian J.PG Anaesth. 49 (4) : MANAGEMENT 300 - 307

INDIAN JOURNAL OF ANAESTHESIA, AUGUST 2005 300

AIRWAY MANAGEMENT IN CHILDREN Dr. Pankaj Kundra1 Introduction Paediatric airway management remains the most daunting task before the anaesthesiologist. However, the laryngeal structures are so soft and pliable that external laryngeal manipulation of the airway makes the task much easier than expected. Often in the absence of a fibreoptic scope unconventional or alternative methods are used to secure the airway with success. Success of any such technique depends upon constant maintenance of an unobstructed airway and sufficient satisfactory depth of anaesthesia during the airway manipulation.1 Difference between adult and paediatric airway Understanding the anatomical and physiological features of paediatric airway facilitates the development of a rational set of strategies to manage normal and difficult paediatric airway patients. When the differences are understood it will be clear that paediatric airway is a different airway and not a difficult airway. Infants have small nares and nasal passages. In infants head is large compared to body size resulting in automatic sniffing position without elevation of occiput. Infants have a large tongue in relation to oral cavity. Base of tongue is situated in close proximity to laryngeal inlet. This caudal insertion is called glossoptosis. Tonsils are small in newborn but it grows to maximal size at 4 – 7 years of age. Enlarged tonsils may obscure laryngeal view or may interfere with mask ventilation. In infants epiglottis lies at the level of C1 (adults C3) touching the soft palate separating oesophageal inlet from laryngeal inlet2 hence infants are obligate nose breathers till 2 – 6 months of age, the ability to breath orally is age related and increases with postnatal age.3 The epiglottis in infants is large stiff and omega shaped compared to short broad and flat epiglottis of adults (fig. 1). Epiglottis sits at 45o angles to anterior pharyngeal wall (adults 20o), as a result of which epiglottis should be picked up with the blade for better visualization of glottis. Larynx lies in a 1. M.D.,MAMS, FIMSA, Prof. 2. M.B.B.S., Junior Resident Dept. of Anaesthesiology and Critical Care Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry 605006 Correspond to : Dr. Pankaj Kundra D – II/21, JIPMER Campus. Pondicherry 605006, India E- mail : [email protected], [email protected]

Dr. Hari Krishnan S.2 more cephalic position C3 – C4 at birth, C4 – C5 at 2 years of age, C5 – C6 by adulthood (fig. 1). A cephalic and superior position on larynx in infants creates more acute angulations between glottis and base of tongue hence posterior displacement is often necessary to improve the view. Larynx is funnel shaped (cylindrical in adults) till 6–8 years of age because cricoids cartilage (glottis in adults) is the narrowest part of airway. The vocal cords are bow shaped making an angle with anterior commissure, where as the plane of vocal cords is perpendicular to long axis of trachea and vocal cords are linear in adults (fig. 1). This angulations of vocal cords increase the chance of endotracheal tube (ETT) abutting the anterior commissure during blind intubation.

Fig. 1 : Schematic diagram showing the difference between adult and paediatric airway.

Trachea in infants is short narrow and angled posteriorly resulting in accidental endobronchial intubation or extubation with changes in head position. Ribs are horizontal with decreased anterior posterior and cephalic movements; hence the diaphragm is the mainstay of ventilation in neonates. The angle formed by abdominal wall and diaphragm is more acute in infants, which reduces the mechanical efficiency during contraction. In addition infants have higher percentage of type II fibres4 (fast twitch low oxidative) in their respiratory musculature leading to early appearance of respiratory fatigue. Congenital airway anomalies and airway management in these children Paediatric airway may be complicated by a number of syndromes involving head neck and cervical spine. These syndromes may result in difficulty in establishing or maintaining gas exchange via a mask, an artificial airway or both (table 1).

KUNDRA, KRISHNAN : AIRWAY MANAGEMENT IN CHILDREN

Table - 1 : Congenital syndromes associated with difficult airway.

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Table - 2 : Agents used for sedation Drugs

Advantages

Disadvantages

Anatomical Location

Syndrome

Anomaly

Midazolam

Amnesia, reversible

Airway reflexes not blunted

Head

Hydrocephalus

Macrocephaly

Opioids

Reversible

Risk of apnoea

Mandible

Pierre Robin Sequence and Treacher Collin’s Syndrome

Micrognathia & Mandibular Hypoplasia

Ketamine

Mid Facial

Apert’s Syndrome

Maxillary Hypoplasia

Adequate spontaneous ventilation. Prevents airway reflexes during airway manipulation

Post anaesthetic delerium, Sympathetic stimulation. Increased airway secretions. No reversal agent

Temporomandibular Joint

Arhrogryposis Cocayane Syndrome

Ankylosis

Mouth and Tongue

Down’s Syndrome

Macroglossia

Mucopolysaccharadosis

Macroglossia

Freeman Sheldon Syndrome

Microstomia

Neurofibromatosis

Masses obstructing airway

Struge Weber Syndrome

Masses obstructing airway

Dental

Cocayane Syndrome

Protruding Incisors

Cervical Spine

Klippel- Fiel Syndrome

Limited Mobility

Down’s Syndrome

Instability

Airway assessment Prediction of difficult airway by the Samsoon and Young modification of Mallampati classification in 476 children between 0 (new born) to 16 years of age suggested an inaccurate prediction of a poor view during direct laryngoscopy. The assessment is often hampered by lack of co-operation in infants and young children.5 No control trials are yet available for evaluation of mandibular space, neck mobility and jaw movements to predict difficult laryngoscopy in paediatric population. Thus measurement of mentohyoid, thyromental, mandibular and inter dental lengths have no value to predict difficult airway in paediatric patients. History of snoring,6 apnoea, daytime somnolence and stridor may be indicative of airway obstruction, which may be exaggerated after induction. Physical examination should include evaluation of the size and shape of head, gross facial features, size and symmetry of mandible, size of tongue, prominence of upper incisors and range of motion in jaw, head and neck. Anaesthetic techniques In patients with difficult airway an awake intubation is often the primary approach of airway management under sedation and adequate application of local anaesthetics to the airway. Various agents have been used for sedation. It is important to preserve spontaneous ventilation during sedation (table 2).

The advantages of awake intubation are preserving of normal airway tone and respiratory efforts. The disadvantages are a struggling child, increased haemodynamic responses and the risk of raise in intracranial pressure.7 We suggest a plan for airway management in anticipated difficult airway. Inhalational Induction In child with difficult but “uncompromised airway” inhalation induction is by far the preferred choice. The success of inhalation induction will depend upon the maintenance of airway patency throughout induction and ensuring adequate depth of anaesthesia before airway manipulation. Halothane is the agent of choice. Sevoflurane can also be used but because of its low solubility the depth of anaesthesia rapidly diminishes during laryngoscopy.8 However, rapid recovery is one of the features that can be of immense advantage in a child who develops airway obstruction following induction. The choice of an inhalational agent becomes irrelevant if a smaller size endotracheal tube is used as a nasopharyngeal airway in maintaining a patent upper airway and serve as a conduit to deliver uninterrupted anaesthetic agent.1,9 In the meanwhile, the mouth or the other nostril can be used for securing the airway.1 This facilitates control of the anaesthetic depth necessary for airway manipulation. The same endotracheal tube can be advanced into the glottis. The depth of anaesthesia can be maintained if inspired agent concentration is sufficient to offset the dilutional effects of room air. The advantage of this technique is that spontaneous ventilation is preserved during airway instrumentation. Intravenous induction Targeting an adequate plane of anaesthesia without compromising spontaneous ventilation is difficult with intravenous induction agents. Propofol provides rapid awakening and blunts airway reactivity. It is a good drug that permits a quick assessment of the laryngoscopic airway grade. In addition a better control of the airway can be achieved with laryngeal mask airway (LMA) insertion under propofol. The main disadvantage is the risk of apnoea, which warrants extremely careful titration of an effective dose.

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Table - 3

Fig. 2 : Different blades used for laryngoscopy in children A - Magill’s blade B - Macintosh blade C - Bizzari-guffirda blade D - Wisconsin blade

Topical anaesthesia Topical anaesthesia of airway improves child’s acceptance of an airway device and blocks airway reflexes. It can be used in conjunction with either inhalational or intravenous induction once sufficient anaesthetic depth is reached for the child to tolerate laryngeal stimulus. Lignocaine 10% spray is highly effective and care should be taken not to exceed the toxic dose limit. Except for translaryngeal block all techniques used in adults can be used in children. Nebulized lignocaine is particularly useful and can be used preoperatively or during induction with an inline attachment for nebulization to the anaesthetic circuit (table 3).

Patient weight

4% Lignocaine (ml)

Normal saline (ml)

10 – 14.9

0.5

0.5

15 – 19.9

1.0

1.0

20 – 24.9

1.5

0.5

25 – 29.9

2.0

30 – 34.9

2.5

35 – 39.9

3.0

Rigid laryngoscopy The keys for success with conventional rigid laryngoscopy includes age appropriate positioning, proper equipment selection, meticulous technique, minimal number of attempts and optimal external laryngeal manipulation (OELM) Ideal position for infants and children under 2 years of age is slight head extension without elevation of head with a roll under shoulders.10 A roll under the shoulders helps to keep both the head and the shoulders lie in the same horizontal line. OELM is particularly useful for children with limited mobility of cervical vertebrae and in infants.

Optimize child with premedication Inhalational Induction Assess airway patency on spontaneous ventilation (Airway obstruction despite oropharyngeal airway?)

No airway obstruction

Airway obstructi

Maintain anaesthesia

Use LMA

Intubation Success

Obstruction relieved

Awaken

Type of surgery

Aspiration likely

Aspiration unlikely

Failure

Intubation Choices

Non Surgical

Obstruction persists

Surgical

1. Direct Laryngoscopy 1. PNC & TTJV* η Special Blades 2. PDC** η Retromolar approach 3. Tracheostomy 2. Flexible Fibreoptic Scope o 3. 70 Rigid Nasendoscope

LMA as conduit Continue LMA 1. 2. 3. 4.

Blind intubation Fibreoptic assisted Guide wire assisted Fibrescope and Guide wire

3. Blind Techniques η Tactile η Light wand η Retrograde 4. Combined Technique η Retrograde wire and fibreoptic * PNC & TTJV = Percutaneous needle cricothyrotomy and transtracheal jet ventilation ** PDC = Percutaneous dilational cricothyrotomy

Fig. 3 : Laryngoscope blades

Choosing laryngoscopes In general straight blade laryngoscopes are easier to use in infants and small children because of better alignment of airway axis and reduced need for displacement of soft tissue structures. Depending on the clinical situation certain modified blades may be more effective for glottis visualization (table 4). Retromolar approach If difficulty is due to small mandible or a large tongue this approach helps. The blade is introduced from the extreme right corner between the tongue and lateral pharyngeal wall. The blade is advanced while staying to the right overlying the molars, until epiglottis or glottis is seen. The proximal end of the blade is then brought to the midline. If glottis is not visualized the head can be turned

KUNDRA, KRISHNAN : AIRWAY MANAGEMENT IN CHILDREN

to the left to improve visualization. The higher rate of success is due to bypassing of tongue, incisors and maxillary structures.11 Table - 4 Clinical situation

Modifications

Examples

Limited mouth opening

Reduced step height and area of flange

Miller blade (fig. 3)

Reduced mandibular space

Wide blade effectively compresses tongue in mandibular space

Bizzari-Guffirda blade (fig. 2C)

Macroglossia

Sides of tongue hindering vision, blades with adequate cross sectional area with a slight opening in vertical plane/tubular in cross section helps

Wisconsin blade (fig. 2D, 3) Magill’s blade (fig. 2A)

Anterior larynx

Blade with more pronounced terminal curve enables the hyoid cartilage to be reached via the vallecula effectively pushing it forward

Fink’s blade Philip’s blade

Blind nasal intubation A well lubricated softened endotracheal tube (ETT) is introduced into a naris. The left naris is preferred as the leading edge stays in midline in hypopharynx, if right naris is used the leading edge frequently hitches the right vallecula. The ETT is directed into glottis by hearing for breath sound, or by capnograph trace. Successful placement often will need manipulation of ETT, patients head and the larynx. A stylet with 30o angle can be placed into ETT after it is placed in nasopharynx.12 Posterior manipulation of stylet will displace the distal end of ETT anteriorly and into the glottis. Elective blind nasotracheal intubation in prone position for a neonate with Pierre-Robin sequence has also been described.13 Higher failure rates are found in patients with mid facial hypoplasia. Laryngeal mask airway LMA has revolutionized difficult airway management in children. LMA has been successfully used in paediatric patients in whom ventilation or intubation are extremely difficult or impossible. LMA has been used. •

In recognized difficult airway for awake tracheal intubation.14



In difficult intubation when mask ventilation is adequate, LMA is used as a definitive airway or as a conduit for intubation.15



When both mask ventilation and intubation becomes difficult, LMA can be used as ventilation device.16

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LMA is available in five sizes for use in paediatric patients. An LMA that is too large will be difficult do place. An LMA that is too small will not form a tight seal and may be difficult to use if positive pressure ventilation is required. Numerous methods are described for placing the LMA in infants and children. The overall success rate of insertion during first attempt ranges from 67–90%. Dubreil et al17 showed the first attempt success rate of LMA size 1 is 67% and size 2 to be 78%, however when mean attempts and complication rate are compared there was no significant difference. O’neil et al18 found partially inflating the cuff resulted in higher success rate and a shorter time of insertion. LMA can be placed while it is rotated 90o in the lateral oropharynx to bypass base of the tongue and then rotated to 90o back to its correct placement. Guedel’s method involved turning back the LMA with mask opening facing the palate once the base of tongue it bypassed it is rotated to 180o. Kundra et al,19 described a partially deflated lateral insertion technique with a better 1st attempt success rate than the classical technique described by Brain. The technique describes a partially inflated cuff by the lateral approach that is relatively free of mechanical hindrance and allows a free passage as used for insertion of the laryngoscope blade. The flexible reinforced LMA (RLMA) resists thinking and can be positioned to minimize interference with surgical procedures involving lead in neck. It is available in sizes 2–5. It is slightly difficult to insert compared to classical LMA. It is particularly useful in children with difficult airway undergoing Head and neck surgeries. LMA proseal specially designed for children (size 1.5–2.5) is now available. One of its main features is the lack of rear cuff. In children there is no difference in ease of insertion and seal pressure between proseal and classical LMA.20 In contrast to adult studies, greater sealing pressure and lower success rate of insertion in proseal LMA was not observed in children. Proseal LMA offers no great advantage against aspiration in children but the provision of drain tube may help to empty air insufflated stomach in paediatric patients with difficult mask ventilation. LMA has been used a conduit for in intubation.21-23 Intubation through LMA can be blind, fibreoptic assisted, light wand assisted or retrograde assisted. Blind techniques has variable success rate. Rowbothom et al24 evaluated the position of LMA (size 1 – 3) in 100 patients. 98% of cases had a patent airway but LMA was in perfect position in 49% of patients, further in 15% of patients impingement of epiglottis into aperture bars was noted hence the safest approach to place ETT through LMA is through fibreoptic scope. Kundra et al19 demonstrated that there occurs a

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direct correlation with the fibreoptic view grading of the glottis through the LMA and subtle airway obstruction. A higher grade was associated with a gradual rise in end tidal carbon dioxide in spontaneously breathing children though the oxygen saturation remains within normal limits in short surgical procedures lasting around half an hour. Blind insertion of ETT through an improperly positioned LMA will lead to airway trauma.

Fig. 4 : Differences in the field of vision between a zero degree endoscope and a 70-degree endoscope

LMA classic Mask size

Patients size

Maximum cuff volume

Largest ETT (ID)

1

Neonates up to 5 kg

4

3.5



Infant 5 – 10 kg

7

4.0

2

Children 10 – 20 kg

10

4.5

2.5

Children 20 – 30 kg

14

5.0

3

Children > 30 kg

20

6.0

Rigid nasendoscopic intubation Conventional laryngoscopy causes distortion of the supraglottic structures and creates difficult conditions for the glottis to be seen. If the airway anatomy is not distorted, glottis might be viewed with greater ease by an endoscope. The 70 degree lateral illumination of the rigid endoscope provides an excellent view of the larynx as soon as the endoscope is passed till the uvula under direct vision (fig. 4). Its oral introduction is atraumatic and does not require additional skills for viewing the larynx. The field of vision has suitable magnification with superior resolution as compared to the frontal/end-on vision of the flexible fibrescope.25 Separately introducing the endotracheal tube and the endoscope permits the use of an endotracheal tube of an appropriate size to be inserted into the glottis. The dynamics of endotracheal tube insertion can be viewed continuously on the screen till the whole process is completed. In the event of the endotracheal tube slipping or being caught at the glottis, it can be manipulated under visual control to negotiate the glottic aperture (fig. 5). Nevertheless, the technique requires co-ordination between both hands (one hand holds the endoscope and fixes the view of the glottis and the other manipulates the endotracheal tube) and one assistant, to stabilize the head and pull the tongue out and to monitor the child as the endoscopist has to constantly focus his attention on the monitor screen.21 Retrograde intubation This method has been used in anticipated or unanticipated difficult airway after convention intubation strategies failed. In children cricothyroid membrane puncture

is made with 20/22 g intravenous cannula. After confirmation of correct position 0.018 / 0.025 inch wire can be threaded in cephalic direction. In patients with limited mouth opening these wires can be retrieved using suction catheters.26 Subsequent tracheal intubation may be performed directly over a wire or the guide wire may be used as a stylet, passed through the suction port of larger fibreoptic bronchoscope. The preferred approach is a fibreoptic with retrograde wire the advantages being. -

Higher success rate Faster intubation Ability to insufflate oxygen through the suction port No hanging up of ETT in glottis No need to rely or anatomic landmarks.

Fig. 5 : Endoscopic views with the rigid nasendoscope used for tracheal intubation. 1. View of the glottis from a distance 2. Closer view of the glottis 3. View of glottis and tube together 4. Lifting the epiglottis with the tube 5. Manipulation of the tube into glottis 6. Final position of the tube

Tactile technique Nasal or oral intubation can be accomplished using this technique. It depends upon palpating epiglottis by second and third fingers inserted through child’s mouth. Once epiglottis is palpated the tube can be guided into the glottis by the fingers.

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Light wand Light wand can be used for orotracheal or nasotracheal intubation. Transillumination is used as a guide for intubation. Tracheal placement results in wellcircumscribed bright glow where as oesophageal placement results in diffuse glow. It is particularly useful in children with limited movement of cervical spine and in patients with limited mouth opening. With light wand for successful intubation there is no need for alignment of oral pharyngeal laryngeal axis. Ease of use is not related to difficulty in direct laryngoscopy or Mallampattii score. The basic construction of a light wand is a light source at the end of a malleable stylet connected to power source in handle.27 Light wands available for children include. • Trach light – Accommodates ETT down to 2.5 mm • Anaesthesia medical specialties – Accommodates ETT down to 3.5 mm • Aaron medical–Accommodates ETT down to 4.5 mm A preselected tube of appropriate size is loaded onto a lubricated light wand stylet. It is then bent to the shape of hockey stick with head in neutral position. Light wand is introduced in the midline, guided by transillumination the light wand is advanced in midline till a wellcircumscribed glow appears below the level of thyroid prominence. The key for successful placement is to stay in midline and anteriorly.28 Once the light wand is in trachea ETT is advanced off the light wand by railroad technique and light wand removed carefully. Complications of light wand include pharyngeal trauma, arytenoid dislocation. The anatomic features that make light wand intubation difficult include short thick neck, large tongue and long floppy epiglottis. Transtracheal jet ventilation (TTJV) TTJV is the percutaneous insertion of a catheter into the trachea through cricothyrorid membrane and ventilation is achieved using jet ventilation. The source gas pressure used for jet ventilation in adults is 50 psi and in children it is 30 psi.29 TTJV is employed as an emergency airway. In infants and children less than 5 yrs of age it has not been recommended because of high incidence of vasovagal events, subcutaneous emphysema, bilateral pneumothorax, inadvertent placement into oesophagus and submucosal false passage in trachea. In infants and children cricoid and thyroid carriages are soft and cricothyroid membrane is poorly defined. Successful placement of catheter into infant trachea is also more difficult to confirm.

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Major limitation of TTJV is the need to maintain patent airway cephalic to the catheter. If upper airway is obstructed life threatening barotraumas occurs. Cricothrotomy It is procedure of choice for emergency access of airway in all patients regardless of age, when conventional means of airway control fails.30 In infants and in small children the soft cartilages, ill defined cricothyroid membrane makes this technique difficult. Patient is positioned with optimal neck extension with rolls under the shoulders, so that larynx comes anteriorly. Cricothyriod membrane is identified. A horizontal incision is made over the skin overlying to membrane with 11 size blade. Incision is deepened and the membrane is punctured with tip of the blade pointing caudally to avoid injury to the oesophagus and vocal cards. Using a curved haemostat pointing caudally the entry point is widened and ETT or tracheostomy tube is inserted into the trachea. Percutaneous dilatational cricocthyrotomy (PDC) is a variation of this technique, which uses Seldinger method for insertion. Various kits are available (e.g. Pedia trake). Only limited data are available of their use in paediatric age group hence PDC is not recommended for paediatric patients. Complications include bleeding, barotraumas and oesophageal perforation. Postoperative airway problems in children Most commonly occurring post operative airway problems in children include 1. Inability to tolerate extubation. 2. Laryngospasm. 3. Post intubation croup. Other airways problems related to intubation are mucosal lacerations in airway, arytenoids dislocation, dental, temporomandibular joint trauma. They are rare with properly performed laryngoscopy and intubation. Inability to tolerate extubation Inability to tolerate extubation may occur commonly due to airway obstruction or due to hypoventilation syndromes. It should be borne in mind that extubation has a potential of leading to a reintubation. Reintubation may become a problem in children in whom securing the airway had been difficult or would now be difficult due to limited access following surgery. For such children it is wise to have a strategy that permits continued administration of oxygen or provision for ventilation. This is achieved by use of reintubation guides or tube exchangers. Catheters used as reintubation guides in paediatric practice include Cooks

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airway exchange catheter, Sheridan tracheal tube exchanger and Cardiomed endotracheal ventilation catheter, the outer diameters of which range from 2.0 – 5.8mm. The identification of patients with a high risk for post extubation complications is largely anecdotal. Children undergoing laryngoscopy, uvulopalato-pharyngoplasty, thyroid surgery, maxillofacial surgeries are more prone. Extubation in fully awake condition and/or with reintubation guides in situ avoids most of the catastrophic airway complications in the early postoperative period. Laryngospasm The incidence of perioperative laryngospasm is about 18/1000 patients in the age group of 0–9 years of age.31 Infant’s 1–3 mo of age have highest incidence. The factors associated with increased risk of laryngospasm are presence of nasogastric tube, oral endoscopy surgeries, during extubation. Inadequate anaesthetic depth is an important factor contributing to laryngospasm during extubation done in lighter planes. Laryngospasm occurs in response to glottis or supraglottic mucosal stimulation involving apposition of structures at three levels 1. Supraglottic folds. 2. False vocal cords. 3. True vocal cords. Fink32 proposed a dual mechanism for closure of larynx. Firstly, a shutter effect can be seen due to the closure of the vocal cords, which in turn leads to increase in translayrngeal pressure gradient. The soft tissues of the supraglottic region become rounded and redundant due to the shortening of thyrohyoid muscle, drawn into the laryngeal inlet (Ball valve effect). Stridor gets manifested due to intermittent closure of glottis. Prevention Prevention is the ideal remedy. Patients with known risk factors may be given intravenous lignocaine 2 mgkg-1 given slowly over a period of 30 sec, one min before extubation. To derive any benefit from lignocaine administration, extubation should be done before signs of swallowing activity appear.33 Another preventive measure proposed is application of local anaesthetic agents to the supraglottic mucosa. Lee and Downes34 suggested. “The infant or child before tracheal extubation should open his eyes or mouth spontaneously, move all extremities vigorously and resume a normal breathing pattern after a cough.” to prevent laryngospasm. Extubation under surgical depth of anaesthesia is advocated by some; however, no data are available to support this view. This practice may lead to premature transfer of children to the recovery room where

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they may be prone to hypoventilation or respiratory obstruction. Management Incomplete obstruction is associated with audible inspiratory or expiratory sound, if obstruction progresses tracheal tug, paradoxical respiratory movements of chest and abdomen develop. Once complete obstruction develops audible sounds cease. One must remember that the primary concern during laryngospasm is oxygenation of the patient and not intubation. Several therapeutic manoeuvres have been suggested. 1. Removal the irritant stimuli like debris from larynx. 2. Forward jaw thrust at the temporomandibular joint by applying pressure on the ascending rami of mandible. This manoeuvre lengthens the thyrohyoid muscle and unfolds the soft supraglottic tissue. 3. Facilitate ventilation by applying gentle continuous positive airway pressure with 100% oxygen by a tight feeling face mask. Any measure of laryngoscopy and intubation attempt may turn incomplete obstruction to complete one. If these methods do not help and if the child remains hypoxic Succinyl choline 0.5 mgkg-1 relieves laryngospasm. In the event of bradycardia, atropine should be administered concomitantly ensuring adequate oxygenation with 100% oxygen through a tight fitting face mask. Post intubation croup It is caused by inflammation of subglottic region due to mechanical irritation of ETT. Contribution factors are age (1–4 years), trauma during intubation, a tight fitting ETT with no leak at 25 – 40 cm H2O, surgery in neck region, children with previous history of croup and long duration of intubation (more than 1 hour). Table - 5 : Downes scoring system 0

1

2

Stridor

None

Inspiration

Inspiration & expiration

Cough

None

Hoarse cry

Bark

Retraction & nasal flaring

None

Flaring & suprasternal retraction

Flaring, suprasternal, subcostal, intercostal retractions.

Cyanosis

None

On air

On 40% oxygen

Inspiratory breath sound

Normal

Harsh with rhonchi

Delayed

Clinical features : Stridor occurs soon after extubation (within 1 hr). Maximum intensity is within 4 h

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and complete resolution occurs within 24 hr. In severe forms, subglottic oedema appears as a “steeple sign” in chest radiograph. A scoring system for post extubation croup is described by Downes and Raphaely35 used for classifying croup into mild, moderate and severe (table 5). Normal score is 0 and the maximum score is 10, patient with a score of 7 or more suggests prophylactic artificial ventilation (table 5).

15. Selim M, Mowafi H, AlGhamdi A et al. Intubation via LMA in pediatric patients with difficult airways. Can J Anaesth1999; 46: 891-93.

Treatment 1. Mild: Humidification, oxygen inhalation, hydration

19. Kundra P, R. Deepak and M. Ravishankar. Technique of laryngeal mask airway insertion in children: A rational approach. Paed Anaesth. 2003; 13(8): 685-90.

2.

20. Shimbhori H, Ono K, Miwa T et al. Comparison of LMA. ProsealTM and LMA classicTM in children. Br J Anaesth 2004; 93: 528-31.

3.

Moderate: Add epinephrine nebulization36 (0.25-0.5 ml racemic epinephrine in 2.5 ml normal saline) Severe: Repeat epinephrine nebulization up to three times. If score > 7, consider artificial ventilation

References

16. Denny M, Desilva KA, Webber PA. Laryngeal mask airway for emergency tracheostomy, in a neonate. Anaesthesia 1990; 45: 895. 17. Dubreil M, Laffon M Plaud B et al. Complications and fibreoptic assessment of size one laryngeal mask airway. Anesth Analg 1993; 76: 527-29. 18. O’Neil B, Templeton JJ. Caramico L, et al. The laryngeal mask airway in pediatric patients: Factors affecting ease of use during insertion and emergence. Anesth Analg 1994; 78: 659-62.

21. Hansen J, Joenson H, Hennebeig SW et al. Laryngeal mask airway guided intubation in a neonate with Pierre Robin Syndrome. Acta Anaesthesiol Scand 1995; 30: 129. 22. Heard CM, Caldicott, Fletcher JE et al. Fibreoptic guided tracheal intubation via the Laryngeal Mask Airway in a pediatric patient. A report of series of cases Anesth Analg 1996; 82:1287.

1.

Kundra P, A Vasudevan, M Ravishankar. Video assisted fibreoptic intubation for temporomandibular ankylosis. Ped Anesth 2005. Accepted for publication (4.6.2005).

23. Takafumi I, Kumikof F, Kazaya T et al. Orotracheal intubation through the laryngeal mask airway in paediatric patients with Treacher Collins Syndrome. Paed Anaesth 1995; 5: 129.

2.

Eckenhoff JE. Some anatomic considerations of infants influencing endotracheal anesthesia. Anesthesiology 1951; 12: 401.

3.

Miller MJ, Carlo WA, Strohl KP. Effect of maturation on oral breathing in sleeping premature infants. J Pediatr 1986; 109: 515-19.

24. Rowbothom SJ, Simpson DL, Grubb D. The laryngeal mask airway in children. A fibreoptic assessment of positioning. Anaesthesia 1991; 46: 489-91.

4.

Keens TG, Lanuzzo CD. Development of fatigue resistant muscle fibres in human ventilatory muscles. Am Rev Respir Dis 1979; 2: 139-41.

25. Ravishankar M, Kundra P, Agrawal K et al. Rigid nasendoscope with video camera system for intubation in infants with Pierre-Robin sequence. Br J Anaesth 2002; 88: 728-31.

5.

Koop VJ, Baily A, Vally RD et al. Utility of Mallampati classification for predicting difficult intubation in pediatric patients. Anesthesiology 1995; 83A: 1146.

26. Bhattacharya P, Biswas BK, Bainwal.S. Retrieval of catheter using suction in patients who cannot open their mouths, Br J Anaesth 2004; 92: 888-90.

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