Effects of head posture on the oral, pharyngeal and laryngeal axis alignment in infants and young children by magnetic resonance imaging

Management of the Difficult Airway

ABSTRACT

Airway management is a fundamental component of care during resuscitation of critically ill and injured children. In addition to predicted anatomic and physiologic differences in children compared with adults, certain conditions can predict potential difficulty during pediatric airway management. This review presents approaches to identifying pediatric patients in whom airway management is more likely to be difficult, and discusses strategies to address such challenges. These strategies include optimization of effective bag-mask ventilation, alternative approaches to laryngoscopy, use of adjunct airway devices, modifications to rapid sequence intubation, and performance of surgical airways in children. The importance of considering systems of care in preparing for potentially difficult pediatric airways is also discussed.

Prehospital Drug Assisted Airway Management: An NAEMSP Position Statement and Resource Document

Airway management is a critical intervention for patients with airway compromise, respiratory failure, and cardiac arrest. Many EMS agencies use drug-assisted airway management (DAAM) - the administration of sedatives alone or in combination with neuromuscular blockers - to facilitate advanced airway placement in patients with airway compromise or impending respiratory failure who also have altered mental status, agitation, or intact protective airway reflexes. While DAAM provides several benefits including improving laryngoscopy and making insertion of endotracheal tubes and supraglottic airways easier, DAAM also carries important risks. NAEMSP recommends:DAAM is an appropriate tool for EMS clinicians in systems with clear guidelines, sufficient training, and close EMS physician oversight. DAAM should not be used in settings without adequate resources.EMS physicians should develop clinical guidelines informed by evidence and oversee the training and credentialing for safe and effective DAAM.DAAM programs should include best practices of airway management including patient selection, assessmenct and positioning, preoxygenation strategies including apneic oxygenation, monitoring and management of physiologic abnormalities, selection of medications, post-intubation analgesia and sedation, equipment selection, airway confirmation and monitoring, and rescue airway techniques.Post-DAAM airway placement must be confirmed and continually monitored with waveform capnography.EMS clinicians must have the necessary equipment and training to manage patients with failed DAAM, including bag mask ventilation, supraglottic airway devices and surgical airway approaches.Continuous quality improvement for DAAM must include assessment of individual and aggregate performance metrics. Where available for review, continuous physiologic recordings (vital signs, pulse oximetry, and capnography), audio and video recordings, and assessment of patient outcomes should be part of DAAM continuous quality improvement.

Airway patency in children undergoing magnetic resonance imaging using neck collars: a single center, randomized, double-blind, prospective study

Background and objectives

Maneuvers precluding the downward shift of the mandibula and providing slight extension of the head have been shown to increase upper airway dimensions. This study aimed to investigate the role of Neck Collars (NC) in maintaining airway patency during Magnetic Resonance Imaging (MRI) examination in a pediatric population aged between 0 and 16 years.

Methods

One hundred twenty-five children were recruited in this prospective study. Subjects were randomly assigned to NC group (NC+) or standard imaging group (NC-). Measurements of anteroposterior and transverse dimensions and cross-sectional area were performed to determine the upper airway size at three distinct levels: soft palate, base of the tongue, and tip of the epiglottis.

Results

The anteroposterior diameter and cross-sectional area at the levels of base of the tongue and soft palate were significantly higher in NC+ patients compared to NC- patients. However, anteroposterior dimensions and cross-sectional areas at the epiglottis level were similar in the two groups. When patients were analyzed according to age groups of 0–2, 2–8, and 8–16 years, the anteroposterior diameter and cross-sectional area at the levels of base of the tongue and soft palate were significantly higher in NC+ patients compared to NC- patients in all age groups.

Conclusions

This study clearly demonstrates that the application of a NC may improve retropalatal end and retroglossal airway dimensions in a pediatric population undergoing MRI examination and receiving sedation in supine position.

Structural and functional development in airways throughout childhood: Children are not small adults

Children are not small adults and this fact is particularly true when we consider the respiratory tract. The anatomic peculiarities of the upper airway make infants preferential nasal breathers between 2 and 6 months of life. The pediatric larynx has a more complex shape than previously believed, with the narrowest point located anatomically at the subglottic level and functionally at the cricoid cartilage. Alveolarization of the distal airways starts conventionally at 36-37 weeks of gestation, but occurs mainly after birth, continuing until adolescence. The pediatric chest wall has unique features that are particularly pronounced in infants. Neonates, infants, and toddlers have a higher metabolic rate, and consequently, their oxygen consumption at rest is more than double that of adults. The main anatomical and functional differences between pediatric and adult airways contribute to the understanding of various respiratory symptoms and disease conditions in childhood. Knowing the peculiarities of pediatric airways is helpful in the prevention, management, and treatment of acute and chronic diseases of the respiratory tract. Developmental modifications in the structure of the respiratory tract, in addition to immunological and neurological maturation, should be taken into consideration during childhood.

The Effects of a Shoulder Roll During Laryngoscopy in Infants: A Randomized, Single-Blinded, Crossover Study

BACKGROUND

The use of a shoulder roll to view the glottic opening during direct laryngoscopy in infants has been recommended but is not evidence based.

METHODS

Twenty infants with normal airways, <6 months of age undergoing elective surgery under general anesthesia were randomized to undergo direct laryngoscopy first with a 2-inch vertical shoulder roll and then without, or vice versa. The primary outcome was the difference in the vertical distance between the angle of the laryngoscopist's eye and the operating room table in the 2 positions. Also, the views of the glottic opening in both positions were recorded for each infant and analyzed by a blinded investigator using the percent of glottic opening (POGO).

RESULTS

Twenty infants completed the study without complications. The vertical distance did not differ significantly whether the shoulder roll was placed first or second, and there was no evidence of a differential carryover effect in the crossover design (P = .268). The main effect of the shoulder roll on the mean (95% confidence interval [CI]) vertical distances without 47.8 cm (43.5-52.1) and with the shoulder roll 37.2 cm (33.3-41) yielded a mean (95% CI) vertical difference of 10.6 cm (9.3-11.79; P = .0001). The median (interquartile range [IQR]) POGO scores without 100 [86.2, 100] and with the shoulder roll 97.5 [80, 100] did not differ (median difference [95% CI]: 0 [-20 to 0]; P = .39).

CONCLUSIONS

A 2-inch shoulder roll lowers the line of sight of the glottic opening compared with no shoulder roll, without affecting the view of the glottic opening during laryngoscopy in infants.

The effect of placement of a support under the shoulders on laryngeal visualization with a C-MAC Miller Video Laryngoscope in children younger than 2 years of age

BACKGROUND

We aimed to evaluate glottis visualization and time to intubation in children younger than 2 years of age during laryngoscopy performed with a C-MAC Miller Video Laryngoscope in a position determined by placing a folded towel under the shoulders to align the oral-pharyngeal and laryngeal axes in the horizontal plane.

METHODS

Ninety-six children younger than 2 years of age, who were classified by the American Society of Anesthesiologists as having a physical status I or II and who were scheduled for elective surgery necessitating endotracheal intubation under general anesthesia, were included in the study. All patients were intubated with a C-MAC Miller Video Laryngoscope. The children intubated by placing a folded towel under the shoulders were categorized as Group 1 (n = 48), and the children intubated without placement of a folded towel were categorized as Group 2 (n = 48). The percentage of glottis opening and Cormack-Lehane Scores, values of visual analogue scale to determine the ease of using a C-MAC Miller Video Laryngoscope, time to intubation, number of intubation attempts, optimization procedures and complications were recorded for all children.

RESULTS

There was a statistically significant difference between Group 1 (mean ± SD; 97.71 ± 4.24) and Group 2 (mean ± SD; 94.17 ± 7.09) in terms of the percentage of glottis opening scores (P = 0.004). The mean difference in the percentage of glottis opening scores (95% confidence interval) between the groups was 3.54 (1.17-5.90).

CONCLUSION

We showed that a folded towel placed under the shoulders in children younger than 2 years of age improves glottis visualization provides ease of use of the C-MAC Miller Video Laryngoscope. Therefore, we think that the placement of a folded towel under the shoulders during the use of a C-MAC Miller Video Laryngoscope may be useful for airway management in children younger than 2 years of age.

Magnetic resonance imaging of the larynx in the pediatric population: A systematic review

BACKGROUND

Magnetic Resonance Imaging (MRI) techniques to image the larynx have evolved rapidly into a promising and safe imaging modality, without need for sedation or ionizing radiation. MRI is therefore of great interest to image pediatric laryngeal diseases. Our aim was to review MRI developments relevant for the pediatric larynx and to discuss future imaging options.

METHODS

A systematic search was conducted to identify all morphological and diagnostic studies in which MRI was used to image the pediatric larynx, laryngeal disease, or vocal cords.

RESULTS

Fourteen articles were included: three studies on anatomical imaging of the larynx, two studies on Diffusion Weighted Imaging, four studies on vocal cord imaging and five studies on the effect of anaesthesiology on the pediatric larynx. MRI has been used for pediatric laryngeal imaging since 1991. MRI provides excellent soft tissue contrast and good visualization of vascular diseases such as haemangiomas. However, visualization of cartilaginous structures, with varying ossification during childhood, and tissue differentiation remain challenging. The latter has been partly overcome with diffusion weighted imaging (DWI), differentiating between benign and malignant masses with excellent sensitivity (94-94.4%) and specificity (91.2-100%). Vocal cord imaging evolved from static images focused on vocal tract growth to dynamic images able to detect abnormal vocal cord movement.

CONCLUSION

MRI is promising to evaluate the pediatric larynx, but studies using MRI as diagnostic imaging modality are scarce. New static and dynamic MR imaging techniques could be implemented in the pediatric population. Further research on imaging of pediatric laryngeal diseases should be conducted.

Improvement of laryngoscopic view by hand-assisted elevation and caudad traction of the shoulder during tracheal intubation in pediatric patients

Pediatric patients have large heads and relatively small bodies, making it difficult to perform intubation even in the sniffing position. Therefore, this study was planned on the assumption that hand-assisted elevation and caudad traction of the shoulder (HA-ECTS) would compensate for the laryngoscopic view. In this observational study, 45 pediatric patients aged 0–36 months with an ASA physical status of I-III and scheduled for elective surgery under general anesthesia were enrolled. HA-ECTS was defined as hand-assisted personalized traction in the upper and caudad directions with both hands under the lower cervical area. The POGO (percentage of glottis opening) score, MO (mouth opening), and LHS (laryngoscopic handling score) were compared before and after HA-ECTS. The median [range] POGO score was 30[10–50]% and 60[15–80]% before and after HA-ECTS, respectively (median difference, 20; 95% confidence interval [CI] 10 to 25%; P = 0.002). MO was 1.0[0.8–1.9] cm and 1.8[1.3–2.0] cm before and after HA-ECTS, respectively (median difference, 0.45 cm; 95% CI 0.25 to 0.60; P < 0.001). The ease of laryngoscopic handling was improved after HA-ECTS(P < 0.001). The application of HA-ECTS to pediatric patients younger than 3 years improved POGO score, MO, and LHS and could prove to be an assistive technique for tracheal intubation.

Laryngeal mask airway Unique™ position in paediatric patients undergoing magnetic resonance imaging (MRI): prospective observational study

Background

Laryngeal mask UNIQUE® (LMAU) is supraglottic airway device with good clinical performance and low failure rate. Little is known about the ideal position of the LMAU on the magnetic resonance imaging (MRI) and whether radiological malposition can be associated with clinical performance (audible leak) in children. The primary aim of the study was to evaluate incidence of the radiologic malposition of the LMAU according to size. The secondary outcome was the clinical performance and associated complications (1st attempt success rate, audible leak) in LMAUs in correct position vs. radiologically misplaced LMAUs.

Methods

In prospective observational study, all paediatric patients undergoing MRI of the brain under general anaesthesia with the LMAU were included (1.9.2016–16.5.2017). The radiologically correct position: LMAU in hypopharynx, proximal cuff opposite to the C1 or C2 and distance A (proximal cuff end and aditus laryngis) ≤ distance B (distal cuff end and aditus laryngis). Malposition A: LMAU outside the hypopharynx. Malposition B: proximal cuff outside C1-C2. Malposition C: distance A ≥ distance B. We measured distances on the MRI image. Malposition incidence between LMAU sizes and first attempt success rate in trainees and consultant groups was compared using Fisher exact test, difference in incidence of malpositions using McNemar test and difference in leakage according to radiological position using two-sample binomial test.

Results

Overall 202 paediatric patients were included. The incidence of radiologically defined malposition was 26.2% (n = 53). Laryngeal mask was successfully inserted on the 1st attempt in 91.1% (n = 184) cases. Audible leak was detected in 3.5% (n = 7) patients. The radiologically defined malposition was present in 42.9% (n = 3) cases with audible leak. The rate of associated complications was 1.5% (n = 3): laryngospasm, desaturation, cough. In 4.0% (n = 8) the LMAU was soiled from blood.

Higher incidence of radiological malposition was in LMAU 1.0, 1.5 and LMAU 3, 4 compared to LMAU 2 or LMAU 2.5 (p < 0.001).

Conclusion

Malposition was not associated with impaired clinical performance (audible leak, complications) of the LMAU or the need for alternative airway management.

Trial registration

Clinicaltrials.gov  (NCT02940652) Registered 18 October 18 2016.

Analysis of the functionally-narrowest portion of the pediatric upper airway in sedated children

The narrowest portions of the pediatric larynx are the glottis and subglottic region. However, the pliable and paralyzed subglottic region, acting like a curtain, is no resistance when passing an endotracheal tube. Therefore, the 'functionally' portion of the pediatric upper airway, which may be the most vulnerable to damage during intubation, is the unyielding portion below the cricoid cartilage. We investigated the functionally-narrowest portion below the cricoid cartilage.Computed tomography (CT) was performed under deep sedation. CT images were used for measurement of dimensions and cross-sectional area (CSA) of the larynx at the level of the cricoid, subcricoid, and trachea. We analyzed the anteriorposterior (AP) diameter, transverse diameter, and CSA below the cricoid cartilage (at the cricoid, subcricoid, and tracheal levels).CT images of 46 children from 8 months to 96 months were reviewed from electric medical record (EMR). The mean ± SD of AP diameter was the shortest at the subcricoid level (cricoid, 105.7 ± 15.8 mm; subcricoid, 94.6 ± 15.3 mm; and trachea, 101.5 ± 15.7 mm; P < .001). The mean ± SD of transverse diameter was the shortest at the trachea level (cricoid, 99.8 ± 12.2 mm; subcricoid, 102.5 ± 13.7 mm; and trachea, 98.8 ± 10.7 mm; P = .01). The mean ± SD of CSA was the smallest at the subcricoid level (cricoid, 8781.5 ± 1963.3 mm; subcricoid, 8425.0 ± 2025.7 mm; and trachea, 8523.7 ± 1791.1 mm; P = .02). The AP diameter at the subcricoid level was narrower than the transverse diameter at trachea level (mean difference: 4.2 mm, 95% confidence interval [CI]: 0.7-7.7, P = .02).Since the most susceptible portion for airway damage is unyielding portion, our findings suggest that, functionally, the narrowest portion of the pediatric larynx is located in the subcricoid region.

Videographic Assessment of Pediatric Tracheal Intubation Technique During Emergency Airway Management

OBJECTIVES

To examine technical aspects of pediatric tracheal intubation using video recording and to determine the association between tracheal intubation technique and procedural outcomes.

DESIGN

Prospective observational study.

SETTING

Emergency department resuscitation bay in single tertiary pediatric center.

PATIENTS

Children undergoing emergent tracheal intubation under videorecorded conditions.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A published scoring tool for characterizing patient positioning, intubator kinematics, and adjunctive maneuvers during tracheal intubation was applied to videorecorded pediatric resuscitations when tracheal intubation was performed. Procedural outcomes were measured from video review. Seventy-one children underwent 109 tracheal intubation attempts with an overall first attempt success rate of 69% and a median laryngoscopy duration of 34 seconds (interquartile range, 24-47 s). A significant subset of tracheal intubation attempts were made with the patient's bed at a height below the level of intubator's umbilicus (61%), the patient in a supine position without head elevation (55%), the intubator bent at the waist to greater than 45° (66%), less than 1 cm of mouth opening by the intubator's right hand prior to laryngoscopy (46%), and with the intubator's face less than 12 inches away from the patient's mouth (65%). Adjunctive maneuvers were used in a minority of attempts (cricoid pressure 48%, external laryngeal manipulation 11%, retraction of the right corner of the patient's mouth 26%). On multivariate analysis, including controlling for patient age category and intubator background, retraction of the right corner of the patient's mouth by an assistant showed an independent association with successful tracheal intubation. No other technical aspects were associated with tracheal intubation success.

CONCLUSIONS

Intubators commonly exhibited suboptimal technique during tracheal intubation such as bending deeply at the waist, having their eyes close to the patient's mouth, failing to widely open the patient's mouth, and not elevating the occiput in older children. Retraction of the right corner of the patient's mouth by an assistant during laryngoscopy and intubation was associated with TI success.

Man behind the laryngoscopy is important

Tracheal intubation is the most fundamental and effective resuscitation skill in many emergency situations. It is also performed to facilitate various surgical procedures and mechanical ventilation in critically ill patients. Tracheal intubation is also one of the most commonly taught clinical skills.

Simple method for obtaining the optimal laryngoscopic view in children: A prospective observational study

BACKGROUND

Head and neck positioning has an important effect on laryngeal visualization during laryngoscopy. For small children and infants, a head-flat position is traditionally assumed; however, during laryngoscopy, the optimal head position may result in a superior laryngeal view in certain patients.

METHODS

We investigated whether the alignment of the external auditory meatus and the sternal notch with a pillow with an individualized height is associated with improved laryngeal visualization during direct laryngoscopy in pediatric patients. We enrolled 49 pediatric patients (3 to 6years old) receiving general anesthesia. The percentage of glottic opening score and ease of handling the laryngoscope (range 0-10) were recorded before and after head positioning with the pillow.

RESULTS

Most of the children, except two patients, needed a pillow beneath their head to align the external auditory meatus and the sternal notch. The percentage of glottic opening score was significantly higher after pillow adjustment compared to that in the neutral position (50 [20-80] vs. 90 [37.5-100]; p<0.0001). Handling of the laryngoscope improved with pillow adjustment (7 [6.0-8.0] vs. 9 [8.0-10.0]; p<0.0001). There were no significant complications during intubation.

CONCLUSIONS

Positioning of the head in order to align it with the external auditory meatus and sternal notch was associated with superior laryngoscopic visualization in pediatric patients. This resulted, in a more straightforward laryngoscopic procedure.

TRIAL REGISTRATIONS

http://cris.nih.go.kr identifier: KCT 0001156.

Upper airway modifications in head extension during development

BACKGROUND

One of the requirements of laryngoscopy is to determine which head position will result in optimal visualization. Our hypothesis was that parameters derived from magnetic resonance imaging (MRI) can help quantify the effect of age on airway modifications due to head extension during development.

METHOD

In children undergoing planned MRI, additional sequences on the upper airways were performed: one in a near-neutral position, the other with the head extended at 35°. The axis of the face, the pharynx, the larynx, the trachea, and the line of glottic visualization were determined. The following angles were calculated: the Visu-Lar angle, formed by the line of glottic visualization and the laryngeal axis, and the Phar-Lar angle, formed by the pharyngeal and laryngeal axes.

RESULTS

One hundred and fifty-five patients (1 to 222 months of age [25-145] months) were included and 54% were under general anaesthesia. Age had no effect on the variation in the Visu-Lar angle, which diminished as a function of head extension, nor on the variation in the Phar-Lar angle, which was minimal in the neutral position. During extension, anatomical axes rotated similarly, and the visualization axis rotated the most, followed by the pharyngeal and laryngeal axes. These results were not correlated with general anaesthesia.

CONCLUSION

Regardless of age, head extension diminished the Visu-Lar angle, and increased the Phar-Lar angle. This study supports that, as in adults, head extension is probably the key factor for good visualization conditions during laryngoscopy on children, but clinical data is needed to confirm this result.

Evaluation of effectiveness of the using a pillow in children for dental rehabilitation under general anesthesia in term for facilitate intubation

Background and Objective:

Airway safety may be provided with endotracheal intubation especially for oral procedures because of some potential risks such as aspiration of secretion or foreign bodies. In this study, we aimed to determine whether placing a pillow under the occiput may facilitate endotracheal intubation in non-cooperative children whose extensive dental treatments were planned to take place under general anesthesia.

Methods:

The study was performed in Erciyes University, Faculty of Dentistry between March-July 2014. A total 150 ASA I-II children, between 3-9 years were included in this study. Pillow was folded under the occiput in Group 1 (n=75), patients lay on a flat surface in Group 2 (n=75) during the anesthesia induction and intubation period.

Results:

There were no statistically significant differences between groups regarding the demographic data (age, weight, gender) (p>0.05). Operation times were similar in both groups (p=0.329). The number of intubation attempts was smilar in both groups (p=0.412). The intubation time was longer in group one than in group two (p= 0.025).

Conclusion:

We concluded that, placing a pillow under the patients occiput provided longer intubation time without changing the number of attempts in the normal airway in non-cooperative children whose extensive dental treatments were planned to take place under general anesthesia.

[The influence of airway supporting maneuvers on glottis view in pediatric fiberoptic bronchoscopy]

INTRODUCTION

Flexible fiber optic bronchoscopy is a valuable intervention for evaluation and management of respiratory diseases in both infants, pediatric and adult patients. The aim of this study is to investigate the influence of the airway supporting maneuvers on glottis view during pediatric flexible fiberoptic bronchoscopy.

MATERIALS AND METHODS

In this randomized, controlled, crossover study; patients aged between 0 and 15 years who underwent flexible fiberoptic bronchoscopy procedure having American Society of Anesthesiologists I-II risk score were included. Patients having risk of difficult intubation, intubated or patients with tracheostomy, and patients with reduced neck mobility or having cautions for neck mobility were excluded from this study. After obtaining best glottic view at the neutral position, patients were positioned jaw trust with open mouth, jaw trust with teeth prottution, head tilt chin lift and triple airway maneuvers and best glottis scores were recorded.

RESULTS

Total of 121 pediatric patients, 57 girls and 64 boys, were included in this study. Both jaw trust with open mouth and jaw trust with teeth prottution maneuvers improved the glottis view compared with neutral position (p<0.05), but we did not observe any difference between jaw trust with open mouth and jaw trust with teeth prottution maneuvers (p>0.05). Head tilt chin lift and triple airway maneuvers improved glottis view when compared with both jaw trust with open mouth and jaw trust with teeth prottution maneuvers and neutral position (p<0.05); however we found no differences between head tilt chin lift and triple airway maneuvers (p>0.05).

CONCLUSION

All airway supporting maneuvers improved glottic view during pediatric flexible fiberoptic bronchoscopy; however head tilt chin lift and triple airway maneuvers were found to be the most effective maneuvers.

Effect of a neck collar on upper airway size in children sedated with propofol-midazolam combination during magnetic resonance imaging

INTRODUCTION

Propofol and midazolam are widely used for pediatric magnetic resonance imaging (MRI) sedation. Increasing depth of sedation may be associated with airway obstruction. A neck collar supporting the mandible and maintaining the head in slight extension may be beneficial in maintaining airway patency.

AIM OF THE STUDY

Primary aim: To assess upper airway size with and without a neck collar during pediatric MRI sedation with propofol-midazolam. Secondary aim: To evaluate complications encountered during the procedure.

MATERIALS AND METHODS

Sixty patients aged 2-4 years scheduled for MRI of the brain were selected. They were sedated with intramuscular midazolam 0.1 mg·kg(-1) 30 min before the procedure. Patients were sedated with i.v. propofol 1 mg·kg(-1) and continued with 50-100 μg·kg(-1) ·min(-1) . T1 3D fast-field echo axial sequence from the nasopharyngeal roof to subglottic region was taken with and without application of a neck collar. Airway dimensions were measured and analyzed at the base of the tongue, soft palate, and at the epiglottis.

RESULTS

At the base of the tongue and soft palate, the cross-sectional area (CSA) and the anteroposterior diameter of the airway were respectively statistically significantly higher when the neck collar was applied. The CSA at the epiglottis was significantly less with application of the neck collar. Complications were not significantly different between the two sequences.

CONCLUSION

Application of a soft neck collar in children aged 2-4 years may enhance the retropalatal and retroglossal airway dimensions during pediatric sedation in the supine position.

Assessment of technique during pediatric direct laryngoscopy and tracheal intubation: a simulation-based study

OBJECTIVES

This study aimed to assess the feasibility of characterizing direct laryngoscopy (DL) and tracheal intubation (TI) technique based on videographic review and to determine the association between technical aspects of DL and TI with successful completion of intubation.

METHODS

Physicians in pediatrics, emergency medicine, pediatric emergency, pediatric critical care, and neonatology performed TI on simulators (newborn, infant, and adult). A video laryngoscope was used without a display (ie, as a direct laryngoscope), and video recordings were reviewed. A scoring instrument characterized technical aspects of DL and TI; outcomes related to procedural performance were recorded. Interrater reliability of the instrument was assessed by weighted κ; collinearity was assessed by a correlation matrix. Univariate analysis determined technical aspects of DL and TI associated with outcomes.

RESULTS

Seventy-three subjects performed 206 intubations. Significant differences existed between simulators with respect to the first-attempt success (newborn, 63%; infant, 80%; adult, 42%; P < 0.001), laryngoscopy time (27 seconds vs 31 seconds vs 42 seconds, P < 0.001), and percentage of glottic opening score (68% vs 65% vs 35%, P < 0.001). Interrater reliability for the instrument was good (κ = 0.68); no significant collinearity existed between data points. Position of the tip of the laryngoscope blade in the vallecula and under the proximal epiglottis was associated with improved first-attempt success.

CONCLUSIONS

Pediatric intubation technique can be reliably assessed using videography and video laryngoscopy. Future studies should examine video-based characterization of DL and TI technique in real patients outside the operating room, as well as whether technical aspects of intubation are associated with improved outcomes.

Sniffing position combined with mouth opening improves facemask ventilation in children with adenotonsillar hypertrophy

BACKGROUND

This study evaluates the influence of sniffing position combined with mouth opening on the effectiveness of facemask ventilation in paralyzed pediatric patients undergoing adenotonsillectomy during sevoflurane-N(2)O anesthesia.

METHODS

After Institutional Ethics Committee approval, 40 children 5-11 years of age who were scheduled for an elective adenotonsillectomy operation were enrolled in this prospective randomized study. After routine monitoring and pre-oxygenation, anesthesia was induced with sevoflurane 8% in a mixture of 50% N(2)O-O(2). Three minutes after the administration of vecuronium, the sequence of the positions was randomized. Three positions were applied during facemask ventilation: Position CN (closed mouth - neutral head and neck position), position CS (closed mouth-sniffing position) and position OS (opened mouth-sniffing position). Volume-controlled ventilation was started. Peak inspiratory pressure (PIP), tidal volume (V(T)), expired tidal volume (V(Texp)) and end-tidal CO(2) pressure were recorded. The percent of leakage was calculated. The primary endpoint of this study was the expired tidal volume (V(Texp)).

RESULTS

There was a statistically significant difference among the three positions for V(Texp) and PIP values. The OS resulted in higher V(Texp) values when compared with CN (P=0.022). The OS was significantly better than the other two positions, resulting in lower PIP values (P<0.001 and P=0.004, for CN and CS, respectively). The OS also resulted in less leakage during facemask ventilation when compared with CN and CS.

CONCLUSIONS

Sniffing position combined with mouth opening improves V(Texp) and PIP values during facemask ventilation during sevoflurane-N(2)O anesthesia in paralyzed pediatric patients with adenotonsillar hypertrophy.

Effect of head posture on pediatric oropharyngeal structures: implications for airway management in infants and children

PURPOSE OF REVIEW

Although head and neck posture has direct effects on the upper airway in infants and children, many of these effects remain unclear or not well established. As airway patency and airway access are critical in sedated and/or unconscious children, recent developments in this area should be made known to pediatric anesthesiologists, intensive care physicians and other emergency caregivers.

RECENT FINDINGS

All recent studies observed large interindividual variability in anatomical measurements, especially in trachea length. More evidence has been gained that lateral position improves upper airway patency in sedated children. Several studies brought indirect information on head posture for laryngoscopy and intubation.

SUMMARY

The site of obstruction of the airway in sedated children in different postures is now more clear. Implications of head flexion and extension in intubated children have been extensively studied, and clinical consequences have been detailed. Due to large interindividual anatomic variability, depth marks set on the tubes by their manufacturers and guidelines regarding calculations of insertion depth should be made with caution in infants and neonates. Despite several studies, there is still little scientific evidence regarding proper head posture for laryngoscopy and intubation.

Current world literature

This bibliography is compiled by clinicians from the journals listed at the end of this publication. It is based on literature entered into our database between 1 February 2008 and 31 January 2009 (articles are generally added to the database about two and a half months after publication). In addition, the bibliography contains every paper annotated by reviewers; these references were obtained from a variety of bibliographic databases and published between the beginning of the review period and the time of going to press. The bibliography has been grouped into topics that relate to the reviews in this issue.

Effect of oral appliances on genioglossus muscle tonicity seen with diffusion tensor imaging: a pilot study

OBJECTIVE

The purpose of this study was to examine whether the diffusion tensor imaging (DTI) technique can be used as a modality to represent the structural deformation in the in vivo genioglossus (GG) muscle fibers with oral appliances (OAs).

STUDY DESIGN

Three healthy subjects were recruited for the pilot study. A custom-made OA, which is modified from a tongue retaining device (TRD), was constructed for each subject before the DTI acquisitions. Recordings were made with and without OAs to compare the GG muscle fiber deformation.

RESULT

DTI provided good resolution of tongue muscle fibers in vivo and successful isolation of each muscle fiber bundle. In particular, the GG muscle fiber deformation due to OAs was clearly visualized.

CONCLUSIONS

This DTI technique may be used not only to identify the individual myoarchitecture, but also to assess muscle fiber deformations in vivo, such as constriction, dilatation, and rotation with OAs. Clinical studies for OSA patients will be the next step.