Management of Failed Spinal Anesthesia

Management of Failed Spinal Anesthesia

➧ Failure of a spinal anesthetic is an event of significant concern for both patient and anesthetist when it is immediately apparent, but it can have serious consequences (clinical and medico-legal) if the problem only becomes evident once surgery has started.

➧ This can be a source of pain, anxiety, and psychological trauma to the patient and a cause of stress, complaints, and medico-legal sequelae to the anesthetist.

Prevention is better than cure:

➧ The spinal block should be performed with meticulous attention to detail. 

➧ If there is any doubt about the nature or duration of the proposed surgery, a method other than standard spinal anesthesia should be used.

Management of failed spinal block:

-The precise management of failed spinal block will depend on the nature of the inadequacy and the time at which it becomes apparent. 

-The slower the onset of either motor or sensory block, the more likely is the block to be inadequate, so the more detailed assessment should be. 

-While the onset of spinal anesthesia is rapid in most patients, it can be slow in some; so, ‘transient time’ should always be allowed. 

-However, if the expected block has not developed within 15 min., some additional maneuver is needed, as follows:

1-No block:

Causes:

-Incorrect or ineffective solution was injected. 

-Solution has been deposited in the wrong place. 

Management: 

-Repeating the block or conversion to general anesthesia is the only option.

2-Spinal block of inadequate height:

Causes:

-Some injectate has been lost or misplaced. 

-The level of injection was too low.

-Anatomical abnormality has restricted spread.

Management:

-If a hyperbaric solution was used, flex the patient’s hips and knees and tilt the table head down (Trendelenburg position). This straightens out the lumbar lordosis, but maintains a cephalad ‘slope’ and allows any solution ‘trapped’ in the sacrum to spread further. 

-In an obstetric situation, turn the patient to the full lateral position with a head-down tilt and reverse the side after 2–3 min.

-If a plain (and usually slightly hypobaric) solution has been used, it may help to sit the patient up but beware of peripheral pooling of blood.

-If an intrathecal catheter injection results in an inadequate spread, do not inject more of the same solution because the dose has minimal effect on the intrathecal spread. 

-Either posture should be manipulated as above, or a different baricity of solution should be tried, or the catheter should be withdrawn before the injection is repeated.

3-Unilateral block:

Causes: 

-This is most likely because of positioning. 

-The longitudinal ligaments supporting the cord have blocked spread. 

Management:

-If the operation is on the anesthetized limb, the surgeon should know that the other leg has sensation, and the patient should be reassured and closely monitored. 

-Otherwise, turning the patient onto the unblocked side if a hyperbaric solution was used (or the reverse for plain solutions) may facilitate spread.

4-Patchy block:

The block appears adequate in extent, but the sensory and motor effects are incomplete. 

Causes: 

-The local anesthetic (LA) dose was inadequate.

-The LA was partially misplaced.

Management:

-If this becomes apparent before surgery starts, the options are to repeat the spinal injection or to use IV analgesia, the latter being the only option after skin incision.

-It may not be necessary to recourse to general anesthesia, as sedation or analgesic drugs are often sufficient especially when patient anxiety is a major factor. 

-Infiltration of the wound and other tissues with LA by the surgeon may also be useful in such situations.

5-Inadequate duration:

Causes:

-An inadequate dose of LA was delivered to the CSF. 

-Syringe swap; Lidocaine (intended for skin infiltration) was confused for bupivacaine. 

-The operation has taken longer than expected.

Management: 

-Sedation, IV analgesia, or infiltration of LA may be adequate, but often the only option is to convert to general anesthesia.

Repeating the spinal block:

➧ If no effect at all was seen 15-20 min. following the injection, it seems reasonable to repeat the block, paying close attention to avoiding the potential pitfalls. 

➧ In all other situations besides total failure, there must be some LA already in the CSF, and anxieties relating to several issues have to be taken into account: 

1-A restricted block may be due to an anatomical factor, impeding the physical spread of the solution, and it may have the same impact on a second injection, resulting in a high concentration of LA at or close to the site of injection leading to neurotoxicity.

2-Barriers to spread within the subarachnoid space may also affect epidural spread (and vice versa), so an attempt at epidural block may not succeed either.

3-Repeated injection in response to a poor quality block may lead to excessive cephalad spread with the potential for cardiovascular instability, respiratory embarrassment, or total spinal anesthesia, so a lower dose should be used to reduce this risk. 

4-A good quality, but unilateral block, might lead to an attempt to place a second injection into the ‘other’ side of the theca, but the risk of placing the second dose on the same side must be significant. 

5-A block of inadequate cephalad spread might be overcome by repeating the injection at a higher level, but should only be attempted when there is a considerable indication for a regional technique.

6-When a repeat block is considered, the adjacent nerve tissue is already affected by LA action, so the risk of direct needle trauma is increased.

Recourse to general anesthesia:

➧ There are many ways in which an inadequate block might be ‘rescued’: 

-General anesthesia must be considered if one or two simple measures have not rectified matters. 

-Common sense and clinical experience are usually the best indicators of exactly when to convert to general anesthesia. 

-If general anesthesia is induced to supplement a partially effective spinal anesthesia, any degree of sympathetic nerve block will make hypotension more likely.

Postoperative Management:

1-Documentation and follow-up:

-The anesthetic complication details should be fully documented in the notes. 

-The patient should be provided with an apology and a full explanation after the operation. 

-Giving the patient a written summary of events for presentation to a future anesthetist can be very helpful, although care should be taken to prevent medico-legal recourse.

-Rarely, the inadequate spread has been the first indication of pathology within the vertebral canal, so if there is any suspicion, look for symptoms and signs of neurological disease, and consult a neurologist. 

-During follow-up of a patient in whom no block was obtained, the possibility of LA ‘resistance’ may seem an attractive explanation.

2-Investigating LA effectiveness:

-Performing skin infiltration with some of the solutions intended for the spinal injection should demonstrate that it is effective. 

-If the concern continues the operating theater, pharmacy, and anesthetic department records should be cross-checked to see whether other practitioners in the hospital have experienced any problems. 

-Similarly, distributors should be able to check whether other hospitals, which have been supplied with material from the same batch, have reported difficulty.

Read more ☛ Failed Spinal Anesthesia

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Failed Spinal Anesthesia

Failed Spinal Anesthesia

Introduction:

➧ Spinal (intrathecal) anesthesia is one of the most reliable regional block methods: the needle insertion technique is relatively straightforward, with cerebrospinal fluid (CSF) providing both a clear endpoint of successful needle placement and a medium for carriage of local anesthetic (LA) within subarachnoid space. However, the possibility of failure has long been recognized, with an incidence of less than 1% in experienced hands.

➧ Literally, the word failure implies that spinal anesthesia was attempted, but no block resulted or a block results, but is inadequate for the proposed surgery. 

➧ Such inadequate block may be related to the three components of the block: the extent, the quality, or the duration of local anesthetic action, often with more than one of these being inadequate.

➧ The intrathecal injection can go astray within each of the five phases of an individual spinal anesthetic, leading to blocking failure, these being, in sequence: 

1-Lumbar puncture 

2-Solution injection 

3-Spreading of the drug through CSF 

4-Drug action on the spinal nerve roots and cord 

5-Subsequent patient management

Causes and prevention of failure:

1-Unsuccessful Lumbar Puncture (Dry Tap):

-Inability to obtain CSF ‘Dry Tap’, is the only cause of failure which is immediately obvious. 

Causes:

a) Incorrect needle insertion or Poor patient positioning:

Prevention: 

➧ A calm, relaxed patient is more likely to assume and maintain the correct position, so: 

-Explanation (before and during the procedure) and gentle, unhurried patient handling are vital.

-Premedication with light anxiolytic for relaxing the patient. 

-Local anesthetic infiltration at the puncture site is effective without obscuring the landmarks.

-Systemic analgesia (IV or inhalation) helps in achieving the correct position for patients in pain (e.g. from a fractured hip).

b) Anatomical abnormalities of the spine:

-Kyphosis, scoliosis, calcification of ligaments, consequences of osteoporosis, obesity, and patient anxiety, make both positioning the patient and needle insertion more difficult, especially in the elderly. 

Prevention: 

-Good clinical training is the key to success.

-Adherence to the basic rules of positioning, needle insertion, and use of adjuncts.

-Lateral or paramedian approach, especially if the mid-line ligaments are heavily calcified. 

-Ultrasound guidance: a pre-procedure scan can be useful in patients with anatomical abnormality to identify the midline and level of injection and to assess the depth of dura from the skin.

c) Equipment-related factors: A blocked needle lumen:

Prevention: 

-Both needle and stylet must be checked for correct fitness before use.

-The needle should not be advanced without the stylet in place, because tissue or blood clots can easily obstruct the fine bore needles used now.

-Prompt needle withdrawal and 'flush test' to assure patency.

2-Pseudo-successful Lumbar Puncture:

-The appearance of clear fluid at the needle hub is usually the final confirmation that the subarachnoid space has been entered.

a) Epidural 'Top-up' dose:

-Rarely, the clear fluid is not CSF, but LA injected as an epidural ‘top-up’ dose or spreading from the lumbar plexus.

Prevention:

-Unfortunately, a positive test for glucose in the fluid does not confirm that this fluid is definitely CSF because extracellular fluid constituents diffuse rapidly into fluids injected into the epidural space.

b) Congenital arachnoid cyst:

-Another, rarer cause is a congenital arachnoid cyst (Tarlov cyst), which are meningeal dilatations of the posterior spinal nerve root, present in 4.5-9% of the population.

3-Solution Injection Errors:

1. Dose selection:

-The dose injected, within the normal range, has only a small effect on the height of a spinal block but is important in determining the quality and duration of the block. 

➧ The dose chosen will depend on: 

-The specific LA used

-The baricity of LA solution

-The patient’s subsequent posture

-The type of block intended

-The extent and duration of planned surgery

Causes: 

➧ Some anesthetists use lower doses than is traditional, in attempts to either: 

-Minimize hypotension, by producing a unilateral block. 

-Decrease block duration which speeds postoperative mobilization and decreases the need for bladder catheterization.

➧ Such lower doses will increase the margin for error and exaggerate the consequences of other problems such as: 

-Loss of injectate and so risk an inadequate block.

-The ‘dead space’ of the needle and hub will contain a significant proportion of what is a small volume to start with.

2. Loss of injectate:

Causes: 

-Leakage of LA solution through the Luer connection between syringe and needle. 

-Leakage through a defect at the junction of needle hub and shaft. 

➧ Given the small volumes involved, the loss of a few drops can cause a significant decrease in the mass of the drug reaching the CSF, and thus in its effectiveness. 

Prevention: 

-Insert the syringe containing the injectate firmly into the hub of the needle, and check that no leakage occurs.

3. Misplaced injection:

Causes: 

➧ Anterior or posterior displacement of the needle tip from subarachnoid to epidural space:

a) During connection of the syringe to the needle, where deposition of a spinal dose of LA will have little or no effect. 

b) During fluid aspiration for confirmation that the needle tip is still in the correct space, may displace the tip unless performed carefully, as may the force of the injection of the syringe contents. 

Prevention:

-The dorsum of one hand should be anchored firmly against the patient’s back and the fingers are used to immobilize the needle, while the other hand is used to manipulate the syringe.

-After attachment of the syringe, aspirate 0.5-1 ml to confirm the free flow of CSF, and at the end of spinal injection, aspirate 0.5-1 ml, to confirm that the needle tip is still in the subarachnoid space, the aspirated volume is re-injected before the needle is withdrawn. Some anesthetists advocate that this is done halfway through as well, 

c) Tip displacement is an important issue with the ‘Pencil point’ needles, as the opening at the end of these needles is proximal to the tip, so only a minor degree of ‘backward’ movement during syringe attachment may result in epidural injection. 

-Also, the opening of these needles may ‘straddle’ the dura so that some solution reaches the CSF, and some of the epidural space. 

-This may be exaggerated by the dura acting as a ‘flap’ valve across the needle opening. Initially, CSF pressure pushes the dura outwards so that aspiration is successful, but subsequent injection pushes the dura forward and the solution is misplaced. 

-A variant is that the needle tip penetrates the dura, but it is the arachnoid mater that acts as the flap valve so that accidental subdural injection results. 

Prevention: 

-Rotation of the needle through 360 degrees after the initial appearance of CSF, and before check aspiration, as the rotation reduces the risk of the membrane edges catching on the opening.

4. Inadequate intrathecal spread:

➧ Factors affecting the intrathecal spread of a local anesthetic solution: 

-Anatomy of the vertebral canal.

-Solution physical characteristics.

-Gravity.

a) Anatomical abnormality: 

-Abnormalities of the curves of the vertebral column as kyphosis or scoliosis, may interfere with the solution spread.

Examination of the patient should reveal whether this might occur, but it is not possible to predict whether the effect will be excessive spread or failure. 

-A rare possibility, is that the ligaments supporting the spinal cord within the theca, form complete septae which act as longitudinal or transverse barriers to LA spread. This can result in a block that is entirely unilateral or limited cephalad spread.

-Spinal stenosis or other pathological lesions can limit spread, effectiveness, or both.

-Previous spinal surgery or intrathecal chemotherapy may result in adhesions that interfere with LA spread. 

-Increased CSF volume in the lumbar theca can cause restricted cephalad spread of intrathecal injection.

-A variation of this factor is dural ectasia, which is a pathological enlargement of the dura seen in most patients with Marfan’s syndrome and in some other connective tissue disorders. 

b) Solution density (baricity):

-Isobaric solutions, with a density within the normal range of CSF, will block the lower limbs with little risk of thoracic nerve block and thus less hypotension. 

-Plain solutions of bupivacaine, although referred to as isobaric, are actually of lower density to be hypobaric at body temperature (37ºC). They have a less predictable spread than that of a truly isobaric preparation, and the block may be not higher than the second lumbar dermatome with slow onset. 

-Hyperbaric solutions, with a density greater than that of CSF, move under the combined influence of gravity and the curves of the vertebral canal. If the patient is placed supine after the injection of a hyperbaric preparation at the mid-lumbar level, the solution will spread ‘down’ the slope under the effect of gravity to pool at the ‘lowest’ point of the thoracic curve, so exposing all nerve roots up to that level to an effective concentration of LA. (Figure 1)

-However, if a lumbar puncture is performed at the fourth lumbar or the lumbosacral interspace, LA may be ‘trapped’ below the lumbar curve, especially if the patient is in the sitting position during injection and maintained in that position for a period thereafter. This results in a block that is restricted to the sacral segments.

Figure 1: Effects of drug baricity

Prevention:

-Avoiding too low injection level unless a deliberate ‘saddle’ block is intended.

5. Ineffective drug action:

➧ The solution injected reaches the target nerves, but it is ineffective or inactive, with a variety of possibilities: 

a) Incorrect drug injection (Identification error): 

-Using LA for skin infiltration or analgesic adjuvants, used from the same sterile preparation area, instead of spinal LA, may lead to an ineffective block. 

Prevention:

-The use of labeled syringes, but this is not easy within a sterile field. 

-The use of syringes with different sizes for each component of the procedure.

-Minimizing the number of ampoules on the block tray (such as using the same LA for both skin infiltration and spinal anesthesia).

b) Physico-chemical incompatibility: 

-The mixing of two different pharmaceutical preparations raises the possibility of ineffectiveness as a result of interaction between LA and adjuvant.

-Chemical reaction can generate an obvious precipitate, or lower the pH of the LA solution which will decrease the concentration of the unionized fraction which diffuses into nerve tissue resulting in a decreased effect.

-Local anesthetics are compatible with most opioids, but the situation is less definitive with other adjuvants such as clonidine, midazolam, ketamine, and other substances. 

-The stability is unknown when mixing three or more substances together for intrathecal use. 

-The incidence of failure is greater after the addition of a vasoconstrictor solution. 

c) Inactive LA solution: 

-Ester-type LAs, are chemically labile so that heat sterilization and prolonged storage, particularly an aqueous solution, can make them ineffective because of hydrolysis, and hence they need very careful handling. 

-Amide-type LAs (e.g. lidocaine, bupivacaine, etc.) are more stable and can be heat sterilized and stored for several years without loss of potency. 

d) Local anesthetic resistance: 

-Very rarely, failed spinal block has been attributed to physiological resistance to the actions of LA drugs.

-This problem is due to mutation of sodium channels (channelopathy) which is associated with significant neurological diseases such as; intractable epilepsy and chronic pain, however, this does not exist in asymptomatic individuals.

-A history of repeated failure of dental or other LA techniques is accompanied by speculation that the problem is due to sodium channel mutation that renders the drugs ineffective. 

4-Failure of Subsequent management:

➧ Not all of a patient’s claims of discomfort, or pain, during spinal anesthesia, are due to inadequate block.

Causes:

-Lying awake during surgery is not a pleasant experience for most patients, and anxiety alone can cause patient discomfort. 

-Furthermore, operating tables are designed for surgical access, not patient comfort; and intra-abdominal stimuli can result in afferent impulses in unblocked parasympathetic nerve fibers causing unpleasant sensations. 

Prevention: 

-Good preoperative patient counseling followed by a supportive approach from the anesthetist during the operation is important in avoiding such problems. 

-Judicious, and proactive use of systemic analgesic drugs. 

-Sufficient sedation to produce drowsiness, or even sleep (with appropriate monitoring), is indicated except in obstetric situations, where small doses may be useful.

-Distraction techniques such as listening to music.

5-Testing the block:

-It is mandatory to test the level of the block before surgery commences

-Most patients will have some anxiety about the effectiveness of the injection, and this will be increased if testing is started too soon. 

-Conventional practice is to check motor block by testing the ability to lift the legs, followed by testing of sensory block to stimuli such as light touch, cold, or pin-prick.

-It is advisable to start testing in the lower segments, where onset will be fastest, and work upwards. Proving early that there is some effect encourages patient confidence; testing too soon does the opposite. 

-Establishing that the level of block is appropriate for the projected surgery is often taken to demonstrate that the quality of block is adequate also. 

-A covert pinch of the site of the proposed surgical incision may be a better indicator of skin analgesia and can be reassuring if the block has been slow in onset. Asking the surgeon to do the same with toothed surgical forceps after distracting the patient with conversation.

6-Catheter and Combined Techniques:

-The majority of spinal anesthetics involve a single shot of LAs. 

-To take advantage of the rapid onset and profound block of spinal anesthesia, both continuous and combined spinal-epidural techniques have been introduced to increase flexibility. 

-If the catheters are correctly placed, problems of inadequate spread, quality, and duration of effect can be dealt with. 

-However, insertion of an intrathecal catheter can be difficult to achieve in some patients and can result in the misdirection of the LA solution, with the risk of neurotoxicity.

Read more ☛ Management of Failed Spinal Anesthesia

Read more: ☛ Failed Epidural Block

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Pierre Robin syndrome

Pierre Robin syndrome:

Manifestations:

➧ A rare syndrome in which there is a combination of:

-Severe micrognathia

-Posterior prolapse of the tongue

Other congenital abnormalities:

-Cleft palate

-Esophageal atresia

➧ The term syndrome is now reserved for those errors of morphogenesis with the simultaneous presence of multiple anomalies caused by a single etiology.

➧ The term sequence has been introduced to include any condition that includes a series of anomalies caused by a cascade of events initiated by a single malformation.

Pierre Robin sequence:

➧ The common features of which include:

1-Mandibular hypoplasia

2-Glossoptosis (Figure 1)

3-Incomplete cleft palate (Figure 2)

Although all three are not necessarily present.

This results in:

-Respiratory obstruction in infancy

-Failure to thrive

-Occasionally cor-pulmonal

Figure 1: Glossoptosis

Figure 2: Incomplete cleft palate

➧ The Robin sequence may be an isolated abnormality, or it may be part of a syndrome. There may be airway and intubation problems in any of these patients.

Associated syndromes:

➧ Pierre Robin sequence has been reported as occurring in association with:

-Stickler syndrome (20%-25% of these cases)

-Campomelic dysplasia

-Trisomy 11q syndrome

-Deletion 4q syndrome

-CHARGE syndrome

-Velocardiofacial syndrome

-Treacher-Collins syndrome.

➧ These patients frequently require anesthesia at a young age.

➧ Management of long-term airway obstruction is a matter of debate, but at present tracheostomy seems to be back in favor. The mortality from pediatric tracheostomy has declined and it increases the safety of subsequent anesthetics.

Etiology:

➧ The exact causes of the Pierre Robin sequence are unknown. Possible mechanisms include:

-Genetic causes.

-Oligohydramnios, which may limit chin growth.

-Weakness of the facial muscles (myotonia).

-Connective tissue disease.

➧ The genetic causes for some of the isolated cases (Pierre Robin sequence without any associated malformations) may include mutations or deletions of parts of the DNA neighboring the SOX9 gene (located in chromosome 17 (17q24)). This gene provides instructions for making protein SOX9 that regulates the activity of other genes, especially those involved in the development of the skeleton, including the jaw during embryonic development.

Preoperative abnormalities:

1. Many present as difficult or failed intubation during resuscitation at delivery. Hypoxic brain damage may be sustained at this stage.

2. The remainder usually presents within a few hours of birth when the micrognathia and glossoptosis cause breathing and feeding difficulties, with episodes of cyanosis when the child is in the supine position. Feeding difficulties correlate with the severity of airway obstruction. Subsequently, there is a failure to thrive.

3. There was a high incidence of concomitant problems, which included gastroesophageal reflux, congenital heart disease, and pulmonary disease.

4. Jaw index: A new index for defining micrognathia by measurement of three facial dimensions; children with Pierre Robin have an average index of more than 3.6 times the normal value.

5. Cleft palate occurs in 60%, and eye problems in 40% of Pierre Robin patients.

6. Chronic upper airway obstruction can result in cor-pulmonale. An increased pulmonary artery pressure may produce right to left shunting through a patent foramen ovale or a persistent ductus arteriosus.

7. Obstructive sleep apnea may occur and managed by the use of nasal CPAP.

Airway obstruction management:

➧ A sequence of strategies is recommended in an attempt to minimize airway obstruction and allow safe feeding. The treatment required depends upon severity:

-Initially, the neonate is nursed in the prone position. If this fails, prolonged nasopharyngeal intubation may help to protect the airway.

-If respiratory distress and failure to thrive persists, and a lateral X-ray of the neck in the supine position shows upper airway obstruction, suturing of the tongue to the lower gum or lip (tongue to lip adhesion) may be needed. Modified nasopharyngeal tubes or splints have been described. Feeding may be undertaken via a nasogastric or a gastrostomy tube.

-Respiration and oxygen saturation are monitored, and appropriate oxygen supplementation is given. Sometimes tracheostomy may be required, although previously there has been a reluctance to resort to this.

-Benjamin and Walker (1991), classified them into three groups according to the treatment required:

1-Mild group (needing posture alone)

2-Moderate group (needing nasopharyngeal tube)

3-Severe group (needing tracheal intubation or tracheostomy).

-All deaths can occur in the latter group, from hypoxic brain damage at birth.

-As the child grows, the obstruction tends to improve, partly from the growth of the mandible and the size of the airway, and partly as a result of better neurological control of the tongue muscles.

-Problems mainly seem to resolve by the time the child is 6 months old:

-Mild cases could be nursed supine from 3 to 6 months.

In-Moderate group, nasopharyngeal intubation is required for between 14 days and 14 weeks, after which they were nursed prone.

-All could sleep supine by 6 months.

Anesthetic problems:

1. Even in the un-anesthetized infant, during the first few months of life, respiratory obstruction occurs in the supine position. The main mechanism for this is thought to be glossoptosis, prolapse of the tongue backward, but it is now realized that there are multiple factors.

➧ It is believed that obstruction is related to a combination of the anatomical abnormalities of the mandible with functional impairment of the genioglossus and other pharyngeal muscles, that are concerned with the maintenance of the airway.

➧ Varying degrees of obstruction exists, ranging from none at all, to obstruction when the neonate is asleep and, in the worst cases, obstruction in the awake state. In any neonate, obstruction worsens during an upper respiratory tract infection, feeding, and crying.

➧ It is suggested that the site of obstruction varies from patient to patient. From endoscopic observations, these have been classified into:

-Type 1: A true glossoptosis in which the dorsum of the tongue is as opposed to the posterior pharyngeal wall.

-Type 2: The tongue compresses the soft palate against the posterior pharyngeal wall so that all three structures meet in the upper oropharynx.

-Type 3: Medial apposition of the lateral pharyngeal walls.

-Type 4: A sphincteric constriction of the pharynx.

2. Oxygen desaturation and obstructive sleep apnea, detected by pulse oximetry and polysomnography, occur in the majority of neonates and contribute to mortality from obstruction.

3. Gastro-esophageal reflux may be present.

4. The unusual facial configuration, in particular the receding lower jaw, makes it difficult to maintain an airtight fit with an anesthetic mask.

5. Difficult or failed intubation results from a combination of micrognathia, and prolapse or inward sucking of the posteriorly attached, and often enlarged, tongue. This may be compounded by the presence of a tongue tie which, paradoxically, may prevent airway obstruction.
So, intubation problems can be underestimated because of the lack of preoperative airway obstruction. However, once the tongue tie had been corrected, subsequent intubation become easy.

6. Pulmonary edema can occur after relief of airway obstruction following palatal repair of cleft palate.

Airway management:

➧ Monitoring by pulse oximetry, to detect airway obstruction, is crucial.

➧ Several methods have been proposed to overcome the problem of difficult intubation, some under general anesthesia, and some in awake patients. The consensus of opinion now seems to favor awake techniques.

1-Asleep technique with 'Jackson anterior commissure laryngoscope': (Figure 3)

➧ Handler and Keon (1983) described a technique for intubation for the anesthetized spontaneously breathing patient, using 'Jackson anterior commissure laryngoscope':

Figure 3: Jackson anterior commissure laryngoscope

-The head is elevated above the shoulders, with flexion of the lower cervical vertebrae and extension at the atlanto-occipital joint.

-The laryngoscope is introduced into the right side of the mouth. Only the tip is directed towards the midline, the proximal end remaining laterally so that a further 30 degrees of anterior angulation can be obtained.

-The narrow, closed blade prevents the tongue from falling in and obscuring the view of the larynx. When visualized, the epiglottis is elevated, and the larynx entered.

-Intubation is then achieved by passing a lubricated tube, without its adaptor, down the laryngoscope. It is held in place with 'alligator forceps' whilst the laryngoscope is withdrawn.

2-Asleep technique with blind nasal intubation in the prone position:

➧ The prone position avoids the problems in the supine position, this position allows the tongue and mandible to fall forward under the effect of gravity and leave the larynx exposed.

3-Fibreoptic bronchoscopic techniques:

➧ In small infants, the 'tube over bronchoscope' technique is not always possible because of the small size of the tube, therefore a 'Seldinger technique' may be necessary:

-After the administration of atropine, ketamine IM, and topical lidocaine, a fibreoptic bronchoscope (OD 3.6 mm, L 60 cm, and suction channel 1.2 mm) is passed through one nostril.

-The tongue is held forward with 'Magill forceps', until the vocal cords are seen, but not entered, because of the risk of total obstruction.

-Under direct vision, a 'Teflon-coated guidewire' with a flexible tip is passed via the suction channel into the trachea.

-The bronchoscope is carefully removed leaving the wire in place, and an ID 3 mm nasotracheal tube is then passed over it into the trachea.

➧ Pediatric bronchoscopes of 2.5 mm diameter are now available, but their very fineness makes them less easy to handle than the 4 mm bronchoscopes).

4-Awake techniques using 'Holiger pediatric anterior commissure laryngoscope': (Figure 4)

Figure 4: Holiger anterior commissure laryngoscope

5-Laryngeal mask airway (LMA) techniques:

➧ Placement of LMA following topical anesthesia in awake infants and the use of LMA to guide an introducer for subsequent intubation can be used in an emergency, and electively.

6-The use of a lighted stylet:

Read more ☛ Treacher Collins Syndrome

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