Ya Chao Xu

Assessment of small-dose fentanyl and sufentanil blunting the cardiovascular responses to laryngoscopy and intubation in children.

Background:  The authors found no study assessing the efficacy of small‐dose narcotics on the cardiovascular response from intubation in children, so they observed the effects of fentanyl 2 μg·kg−1 and sufentanil 0.2 μg·kg−1 on the cardiovascular changes during laryngoscopy and intubation in children.

Airway anesthesia for awake fiberoptic intubation in management of pediatric difficult airways

1 Brett CM, Davis PJ, Bikhazi G. Anesthesia for neonates and premature infants. In: Motoyama EK, Davis PJ, eds. Smith’s Anesthesia for Infants and Children, 7th edn. St. Louis, USA: C.V. Mosby, 2006: 521–570. 2 Cote CJ. Pediatric anesthesia. In: Miller RD, ed. Miller’s Anesthesia, 6th edn. Philadelphia: Churchill Livingstone Inc., 2005: 2367–2407. 3 Boloker J, Bateman DA, Wung JT et al. Congenital diaphragmatic hernia in 120 infants treated consecutively with permissive hypercapnea ⁄ spontaneous respiration ⁄ elective repair. J Pediatr Surg 2002; 37: 357–366. 4 Paul O, Mely L, Viard L et al. Acute presentation of congenital diaphragmatic hernia past the neonatal period: a life threatening emergency. Can J Anaesth 1996; 43: 621–625. 5 Wilson WC, Benumof JL. Respiratory physiology and respiratory function during anesthesia. In: Miller RD, ed. Miller’s Anesthesia, 6th edn. Philadelphia: Churchill Livingstone Inc., 2004: 679–722.

An intraoral fixation method of endotracheal tube using the surgical suture in pediatric patients

tion of anaesthesia mask for fibreoptic intubation in children. Paediatr Anaesth 1999; 9: 119–122. 5 Holm-Knudsen R, Eriksen K, Rasmussen LS. Using a nasopharyngeal airway during fiberoptic intubation in small children with a difficult airway. Pediatr Anesth 2005; 15: 839– 845. 6 Paterson NA. Management of an unusual pediatric difficult airway using ketamine as a sole agent. Pediatr Anesth 2008; 18: 785–788. 7 Bryan Y, Chwals W, Ovassapian A. Sedation and fiberoptic intubation of a neonate with a cystic hygroma. Acta Anaesthesiol Scand 2005; 49: 122–123. 8 Smith JA, Santer LJ. Respiratory arrest following intramuscular ketamine injection in a 4-year-old child. Ann Emerg Med 1993; 22: 613–615. 9 Antila H, Laitio T, Aantaa R et al. Difficult airway in a patient with Marshall-Smith syndrome. Paediatr Anaesth 1998; 8: 429– 432. 10 Hostetler MA, Barnard JA. Removal of esophageal foreign bodies in the pediatric ED: is ketamine an option? Am J Emerg Med 2002; 20: 96–98.

Anesthesia and airway management for children with macroglossia

wire. Another modification to this technique is using an 8 Fr red rubber tube catheter attached to the insertion cord of the fiberscope (2). Unfortunately, no advanced airway aids of appropriate size were available to us. The operating laryngoscope, in contrast to the anesthesiologists’ conventional laryngoscope blades, Miller ⁄ Macintosh, which displace only anterior structures like tongue from the line of sight, is a hollow device that can displace posterior masses that intrude into the supraglottic region improving glottic view. In our case, the firm masses arising from the cartilaginous part of the larynx and intruding into the membranous part posed difficulty in tube negotiation .The hollow operating laryngoscope displaced the mobile masses to uncover a glottic chink resulting in successful intubation (Figure 3). The operating laryngoscope is a useful aid in the nonemergent limb of failed intubation. Rani A. Surender * Chakravarty Chandrashish* Kumud Kumar Handa† Subramaniam Rajeshwari* *Department of Anesthesiology and †Department of Otolaryngology, All India Institute of Medical Sciences, New Delhi, India (email: rani_kannan2000@yahoo.com)

Measures to decrease failed intubation with the pediatric Bonfils fiberscope by the obscure vision.

glottis. When the Bonfils fiberscope is positioned immediately in front of the glottis, the endotracheal tube (ETT) is advanced over it into the trachea. In children, the epiglottis adherent to the posterior pharyngeal wall may sometimes impede advancement of the Bonfils fiberscope’s tip to align with the glottis. This problem can be solved by following maneuvers in a stepwise progression: chin and tongue lift; external jaw thrust; jaw thrust with maximal neck extension; and finally assistance using a Macintosh laryngoscope. To decrease the risk of the laryngeal and tracheal trauma in pediatric patients, we do not recommend that the Bonfils fiberscope is advanced below the glottis before releasing the ETT (4). After the Bonfils fiberscope’s tip is positioned immediately superior to the glottis, an assistant helps to release the ETT from the tube adapter and advance it into trachea along the Bonfils fiberscope, while the operator carefully maintains the device in a correct position and observes the ETT placement. This can avoid loss of fiberoptic view of the larynx by position change of the device. A main shortcoming of the pediatric version Bonfils fiberscope is lack of a suction channel to allow oxygen insufflation, administration of local anesthetics and suctioning. We often use the two methods to overcome this shortcoming. The first requires attaching a triple stopcock to the tube adapter in order to connect oxygen tubing and a Luer-locked syringe prefilled with lidocaine (Figure 1a). Under direct vision through the Bonfils fiberscope, the supraglottic area and laryngeal aperture are sprayed with aliquots of 1–2 ml of 2% lidocaine via the ETT. The oxygen flow of 5–6 lÆmin allows for higher FiO2 delivery; keeps lens clean; disperses mucous secretions away from the lens and improves lidocaine spray in the airways. The second method involves placement of an end hole epidural catheter in the ETT’s lumina through the tube adapter. The proximal end of the epidural catheter is attached to a triple stopcock and an oxygen supply of 2 lÆmin (Figure 1b). By the triple stopcock, lidocaine is sprayed into the airway. Unlike the flexible FOB, the Bonfils fiberscope is not suitable for the nasotracheal intubation. In the children with severe limited neck extension or mouth opening, or an anterior larynx, moreover, a small fixed anterior curvature of this device (40 ) would make it difficult to negotiate the oro-tracheal angle and may decrease its efficacy for the intubation (5). Fu Shan Xue Xu Liao Yan Ming Zhang Mao Ping Luo Department of Anesthesiology, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100144, China (email: fruitxue@yahoo.com.cn)

Sedation and anesthesia for fiberoptic intubation in management of pediatric difficult airways

provide sufficient pulmonary blood flow to avoid severe cyanosis and protection of pulmonary circulation from excessive blood flow which may result in excessive volume overload of the single ventricle. Extreme care may be taken in avoiding hyperventilation or increasing inspired O2 concentration beyond baseline, as this can rapidly lead to excess pulmonary flow and cardiac failure. These patients may face with devastating consequences with too much oxygen (5). We preferred intravenous anesthesia with fentanyl, ketamin and midazolam as i.v. anesthesia may offer hemodynamic stability in children with single ventricle CHD (6–8). We also recruited high peak inspiratory pressure during pressure controlled ventilation aiming to hyperinflate the patient in order to avoid excessive blood flow in pulmonary circulation via increased pulmonary vascular resistance. Our patient well tolerated hypercarbia around levels of 50 mmHg throughout the operation. We did not have to use catecholamine infusion peroperatively as the patient did not have further hypotension beyond baseline values during the operation. This level of blood pressure was regarded as satisfactory as urinary output was well maintained during intraoperative and the early postoperative period. Blood pressure levels of our patient were consistent with a successfully managed prior single ventricle case presented recently (9). To summarize, we report the anesthetic management of a neonate with very low birth weight (i.e. <1500 g) who has TEF ⁄ EA together with hypoplastic right heart syndrome and tricuspid atresia. Presence of a cardiac anomaly is known to worsen the prognosis of TEF ⁄ EA (10) particularly in neonates with birth weight <1500 g (3). However, with i.v. fentanyl, ketamin, midazolam and rationale ventilatory management aiming to prevent excess pulmonary blood, it was possible to establish successful surgical anesthesia in our patient. Aysu Kocum* Mesut Sener* Halil Tolga Kocum† Esra Caliskan* Nesrin Bozdogan* Hatice Izmirli * Anis Aribogan* *Department of Anesthesiology and †Department of Cardiology, Baskent University Faculty of Medicine, Ankara Turkey (email: aysuinan@yahoo.com)

Safe and successful intubation using a Storz video laryngoscope in management of pediatric difficult airways

SIR—We read, with great interest, the recent letter written by Drs Wald et al. (1) regarding pediatric Storz video laryngoscope (SVL) (Karl Storz, Tuttlingen, Germany) rescue for a difficult intubation in a neonate with Desbuquois syndrome who has a poor glottic view by direct laryngoscopy. We agree with their view that the SVL may serve as a useful alternative when a pediatric difficult airway is encountered, but we would like to make one comment on the anesthesia scheme of this case, and offer a few suggestions on safe and successful intubation using the SVL in management of pediatric difficult airways. For neonates, infants and younger children with a difficult airway, sevoflurane inhalational anesthesia with maintenance of spontaneous ventilation is indeed preferred because child’s airway can be tested by a gradual onset of anesthesia during induction (2). This ensures that child’s airway can safely managed by facemask. In this case, however, 1.2 mgÆkg of propofol was supplemented i.v. after an equilibrated end-tidal concentration of sevoflurane equal to 1.5 minimum alveolar concentration was obtained (1). It puts the patient at increased risk of severe adverse incidents because the spontaneous breathing disappears and ‘cannot intubate–cannot ventilate’ situation occurs (3), especially when propofol is rapidly administered i.v. in pediatric patients. When our plan is to attempt laryngoscopy and intubation under sevoflurane anesthesia, therefore, the inspired concentration of sevoflurane is initially increased gradually to 8%. After the end-expired concentration of sevoflurane reaches 5% or the child’s spontaneous ventilation starts to become shallow, laryngoscopy and intubation are performed. We find that spontaneous breathing can not only be well maintained during anesthesia induction, but also no episodes of breath-holding and coughing are observed during laryngoscopy and intubation (2). As compared to the convenient laryngoscope, the SVL may indeed provide a better glottic view because it can capture images from beyond the tip of the blade and display them on monitors. Moreover, the operators experienced in the convenient laryngoscope can also use the SVL skillfully without any special training because the two devices share some common features. The operator needs only a few cases to become comfortable with the view on the monitor screen, appropriate eye-hand coordination, and the handling characteristics of the instrument. Therefore, it can be used as a primary intubation device or in case of emergency since it does not require extensive patient preparation or personnel assistance when urgent intubation is required. However, several key points for safe and successful intubation using a SVL must be emphasized. 1 When the intubation is performed using the SVL, a malleable intubating style and an adequate angulation of the endotracheal tube (ETT) are necessary for guidance of the ETT tip towards the glottis, especially in the pediatric patients with a micrognathia or an anterior larynx. To avoid airway trauma, a less traumatic and more flexible intubating stylet is preferred. Also the distal end of ETT and intubating stylet is usually bent anteriorly to an angle of 60–90 according to the anatomy of a child’s airway. 2 The SVL presented does not contain a port for suctioning or administering oxygen during intubation. This may not only shorten available time for intubation by apneic oxygenation, but also increases the susceptibility to problems inherent to endoscopes in general, such as fogging of the lens or interference with secretions and blood. Before intubation, therefore, sufficient preoxygenation is required, the SVL blade should be well pretreated with an anti-fog agents and the airway must be satisfactory suctioned. Additionally, the duration of each intubation attempt can not last too long, and SpO2 and ECG must be closely monitored, particular at the neonates and infants with high oxygen consumption relative to reserves. 3 Over-deep insertion of the SVL blade is a common problem, particularly when a Miller SVL blade is used in the infants and smaller children in whom the upper airway is very short. Inserting the SVL blade too deeply into the laryngopharynx may elevate the entire larynx so that the opening of esophagus will be visualized on the monitor rather than the glottis. This problem can be avoided by inserting the SVL blade gradually to make base of tongue, uvula and epiglottis being visualized sequentially on the monitor. 4 When a Macintosh SVL blade tip is placed into epiglottic vallecula, the epiglottis may occasionally obstructs the view to the glottis, especially if the epiglottis is large and floppy. To obtain the adequate exposure of the glottis, the epiglottis has to be gently lifted directly by the Macintosh SVL blade tip. When the laryngeal exposure is also done using the SVL, the external laryngeal manipulation is an effective measure to improve visualization of the vocal cords. 5 An adequate monitor view of the vocal cords can often be obtained rapidly using the SVL, but insertion of the ETT into the trachea may be significantly delayed due to the limited manoeuvrability of the ETT within the oropharynx, which makes it necessary to re-adjust the angle of the ETT tip. As compared to adults, this problem is easier to occur in children because of the smaller oropharyngeal space. It can be, partially, overcome by insertion and steering of the ETT from the angle of the mouth, which increases the sagittal manoeuvrability of the ETT tip. 6 For the patients who can be ventilated but have a failed laryngoscopic intubation, beside the SVL, the fiberCORRESPONDENCE 1251

The measures for assuring correct sizes and depths of uncuffed preformed endotracheal tubes in children with cleft lip and palate

was confirmed by fiberoptic bronchoscopy. The Draeger Apollo anesthesia machine (Draeger Medical, Telford, PA, USA) is equipped with both inspiratory and expiratory spirometers that are located where the breathing circuit connects to the machine. These spirometers provide the flow information necessary to generate flow-volume and pressure-volume loops (both inspiratory and expiratory) on a breath to breath basis. An advantage of this technology is that compliance compensation is used to correct the volume measurements for the circuit compliance which eliminates the need for a sensor mounted at the airway to obtain accurate data on inspiratory and expiratory volumes. Using the spirometer on the Draeger Apollo anesthesia machine, we have applied the principles described by Mahajan et al. to position tracheal tubes in infants and children using pressure controlled ventilation. Following tracheal intubation, the tube is advanced until the Murphy eye has passed 1 cm beyond the vocal cords. The tracheal tube depth relative to the maxillary incisors or alveolar ridge is then noted following careful removal of the laryngoscope. This depth is identified as the minimum tracheal tube insertion depth. Pressure controlled ventilation is initiated, and a reference flow-volume and pressurevolume loop is stored using the spirometer display controls. The tracheal tube is then advanced half a centimeter every two breaths as the flow-volume and pressurevolume display is observed. Based on the compliance changes described by Mahajan (1), the tracheal tube depth at which endobronchial intubation occurs is identified by a greater than 25% reduction in volume on the pressure and flow volume loops. The tube is then withdrawn half a centimeter every two breaths until tracheal positioning of the tip of the tube is identified by an increase in volume on the pressure and flow volume loops that matches the stored reference loops. The tube is then withdrawn an additional centimeter in infants and 2 cm in older children and secured after verifying this depth to be greater than the minimum insertion depth previously identified. This technique, although convenient, has some limitations. Endobronchial tube placement might occur if the compliance decrease observed is due to to lobar ventilation rather than single lung ventilation. The likelihood of this occurring can be limited by careful initial tube positioning and with final confirmatory visual chest inspection and auscultation. Also, an acute change in compliance would impair the utility of this method. Such a change might occur with bronchospasm or mucus plugging of the tube. Finally, the presence of a Murphy eye on the tube may allow for bilateral ventilation from an endobronchial position and confound exact identification of the carinal distance. The clinical impact of this is limited by withdrawal of the tracheal tube at least 1 cm above the identified depth of the carina. In summary, we have described the use of the built-in spirometer on the Draeger Apollo anesthesia machine as a tool for positioning tracheal tubes in infants and children. The technique is simple, requires no additional equipment, and does not add risk. It can also be performed with other ventilators that employ similar technology. Paul A. Stricker John E. Fiadjoe Jeffrey M. Feldman Department of Anesthesiology and Critical Care Medicine, The Children’s Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, PA, USA (email: strickerp@email.chop.edu)

Does an age-based formula predict the appropriate tracheal tube sizes in children?

of cricoid pressure in association with gentle ventilation. If ventilation proves difficult after the application of cricoid pressure, it should be released and gently reapplied to a point where ventilation is unaffected. Afterall, when Sellick introduced this concept in 1961, he stated that ‘during cricoid pressure the lungs may be ventilated by intermittent positive pressure ventilation without risk of gastric distention’ (3). This secondary effect of cricoid pressure may also be useful today. The principle of closing the postcricoid region to prevent against aspiration remains in our opinion sound and lack of evidence should not be cited as a reason for abandoning the practice. The use of suxamethonium also has its detractors. We believe that in terms of aspiration prevention the use of suxamethonium as a muscle relaxant to effect rapid relaxation remains useful. If the recommendations of WEISS and GERBER were followed we would potentially be inducing a child with bowel obstruction or full stomach, using mask ventilation (fair enough), not using cricoid pressure and waiting for a non-depolarising muscle relaxant to work, therefore, potentially leaving the airway unprotected for longer than necessary. Pulmonary aspiration can be catastrophic and aspiration prevention measures are almost as important as oxygenation measures. We must, therefore, do the best we can to reduce that risk. That means, in our opinion, the continued use of ‘careful’ cricoid pressure, the use of suxamethonium to minimise the time that the airway remains unprotected and other measures such as the use of head up tilt, in addition to naso gastric tubes of course. Whilst we agree with much of Weiss and Gerber’s sentiments we feel in this situation time does matter! Robert Walker Benoit Beauve Department of Anaesthesia, Manchester Children’s Hospital, UK (email: birobwalker@qol.com)

Safe oral to nasal tube exchange using the fiberoptic bronchoscope in management of pediatric difficult airway

0.3 mgÆkg. Patient was maintained on O2 and N2O mixture, relaxants, and ventilated with Jackson Rees circuit. Stable hemodynamics were maintained throughout the surgery with fluid management based on body weight. At the end of surgery, Inj.Glycopyrrolate and Inj.Neostigmine were given to reverse muscle relaxation. Patient was extubated after removal of throat pack having met the extubation criteria. Postoperative monitoring was done and the child was kept nil orally and maintained on intravenous fluids. Tongue flap surgery for cleft palate repair involves two surgeries. First, a tongue flap is created to close the palatal defect and it is constructed from the dorsum of the tongue to close a defect in the palate (1). Next, the flap is divided, freeing the tongue from the palate. Airway management for the second surgery is complicated by the flap between the tongue and the palate. Securing the airway for the tongue flap division, the surgery is more challenging (2). After palatoplasty it is advisable to avoid nasal intubation, as this may disrupt the recently constructed flap even after carefully visualized nasotracheal intubation (3). In adult patients, the tongue flap is divided under local anesthesia, by using two silk threads to tie the ends, which prevents bleeding. This requires patient compliance and it is not possible in children (4) and does not offer any protection against aspiration. The molar approach to laryngoscopy reduces the distance from the patients’ teeth to the larynx and prevents maxillary structures coming into the line of view and avoids a large volume of tongue remaining anterior to the blade. It improves glottic view and is recommended in cases with difficult laryngoscopy. The left-molar approach should be part of the anesthesiologist’s armamentarium in cases of difficult laryngoscopy (5). Awake fibreoptic intubation is the gold standard for difficult airway management but failures are reported in up to 13% of cases. In case of failure, a tracheotomy is indicated. This could not be used because of the unavailability of pediatric fibreoptic scope. We used a left molar approach to laryngoscopy and a left-sided intubation to avoid trauma to the midline flap. The Ryle’s tube in the right nostril interfered with the right-sided intubation. Hence, the throat pack was also done from the left side. Our approach to laryngoscopy is safe to the patient. Securing the airway is of utmost importance in this case to prevent aspiration of blood and secretions. This technique is recommended in all cases of difficult laryngoscopy. Shilpa Rao Rajendra Dayabhai Patel Department of Anesthesiology, Seth G.S. Medical College and K E M Hospital, Mumbai 400012, India (email: drshilparao@gmail.com) References