A laryngoscope with a straight blade ( size 1 for term infants, size 0 for premature infants or 00 for extremely low birth weight infants ) is preferred, although some experienced operators use curved blades.
Contents
- 0.1 What size laryngoscope blade should be used to intubate a newborn 32 weeks?
- 0.2 What size endotracheal tube for a 32 week baby?
- 1 How do I know what size laryngoscope blade I need?
- 2 How do I choose ETT size for neonates?
- 3 What is the best laryngoscope blade for infants?
- 4 Which laryngoscope is used for neonates?
- 5 What type of laryngoscope blade is used to intubate an infant and newborn?
- 6 Which laryngoscope blade is usually used for infant intubation?
- 7 What size tube for infant intubation?
What size laryngoscope blade should be used to intubate a newborn 32 weeks?
What is already known on this topic? –
Preterm infants <28 weeks' gestation frequently require tracheal intubation, and frequently undergo multiple unsuccessful intubation attempts. The Neonatal Resuscitation Program recommends the size-0 Miller laryngoscope blade for premature neonates and describes the size-00 Miller blade as optional. The actual dimensions of size-0 and size-00 laryngoscopes vary among different manufacturers.
What size endotracheal tube for a 32 week baby?
Endotracheal tube (ET) size – A rough guide for ET tube size by weight/gestation:
- < 1250 grams (<32 weeks) 2.5 mm ET tube
- 1250 – 3000 grams (32-38 weeks) a 3.0 ET tube
- > 3000 grams (>38weeks) a 3.5 ET tube.
Table 1 is a guide to ET tube size and depth of insertion, measured to the lip and to the ala of the nostril, depending on whether intubating orally or nasally respectively.
How do I know what size laryngoscope blade I need?
Laryngoscope Blades The proper size for a straight (Miller) blade size, according to patient age, is as follows: premature, blade size 0; neonate, 0–1; 1 month to 2 years, 1; 2–6 years, 1–2; 6–12 years, 2; and older than 12 years, 2–3.
What size laryngoscope blade for preterm baby?
Three sizes of blades are used when intubating newborns: 1, 0 and 00. The Newborn Life Support Course recommends using a size 1 blade for term infants, a size 0 for preterm infants and consideration of a size 00 blade for extremely preterm new- borns.
What size laryngoscope blade is recommended to intubate a preterm newborn with an EGA of 32 weeks?
CONCLUSION – In conclusion, C-MAC video laryngoscope Miller blade size 0 is suitable for intubation of preterm neonates. However, further prospective studies are required to corroborate our findings and recognise possible complications.
What is a size 4 laryngoscope blade used for?
4. Discussion – Our study aimed to investigate whether the size of the curved blade laryngoscope affects the outcomes of intubation performed by a novice clinician. The size 4 curved blade group demonstrated longer TSI, lower first-pass and overall success rates, and higher proximal esophagus visualization and esophageal intubation incidence rates than the size 3 curved blade group.
- These findings indicate that the outcomes of intubation performed by novice trainees may be affected by the blade size used.
- Furthermore, the fact that the participants from the size 4 curved blade group showed higher proximal esophagus visualization and esophageal intubation incidence rates and longer TSI than those from the size 3 curved blade group suggests that novice trainees do not fully understand the upper airway anatomy and do not have the skills to correct their mistake when they fail to find the anatomical landmarks in the upper airway.
Most clinicians prefer a Macintosh laryngoscope with a curved blade and typically use a size 3 or 4 blade during laryngoscopic orotracheal intubation on adult patients because it facilitates easy control of the tongue. In terms of the blade size choice, some clinicians mainly utilize size 3 blades and argue that the use of size 4 blades is necessary only in patients who are overweight or have a very long thyromental distance.
Other clinicians claim that size 4 blades are more suitable for tracheal intubation than size 3 blades considering the distance between the upper incisor and hyoid bone. Furthermore, some clinicians recommend the use of a size 4 blade first in all adult patients given that the vertical flange height is similar between size 3 and 4 blades.
Generally, experienced clinicians prefer the use of a specific blade size when performing tracheal intubation on adult patients, although they do not have a problem in performing intubation even when they are handed with a differently sized blade. However, in the present study, we found that novice clinicians performing intubation showed better performance with the use of a size 3 curved blade than a size 4 curved blade.
- The outcomes of tracheal intubation are influenced by interactions between patient factors, clinical settings, and clinician skills.
- In addition, clinicians should acquire cognitive, psychomotor, and affective skills relevant to airway management to perform tracheal intubation well.
- This study compared conventional laryngoscopes with similar shapes but different lengths.
Thus, these devices were not completely different, and the laryngoscopic approach was identical. Hence, the present findings reflect differences in the clinicians’ experiences and skill levels. In particular, considering that the size 4 curved blade group displayed a higher proximal esophagus visualization incidence rate than the size 3 curved blade group, the participants appeared to lack cognitive understanding of the upper airway anatomy, which is necessary for a successful tracheal intubation.
- In general, textbooks and conventional airway management trainings recommend the targeting of the vocal cords when performing tracheal intubation.
- However, they seldom mention the importance of the 3-dimensional anatomical structure of the larynx.
- The larynx inlet is an oblique circular opening, and the boundary is formed superiorly by the epiglottis, bilaterally by the arytenoid folds, and inferiorly by the arytenoid cartilage (i.e., posterior cartilage) and interarytenoid notch.
The vocal cords are deeply located in the larynx and lie inferior to the larynx inlet. Thus, the vocal cords are the ultimate destination when performing direct laryngoscopy and tracheal intubation, but to a limited extent. However, the vocal cords are generally the only landmark used by novice clinicians, which explains their struggle in finding this landmark during laryngoscopy.
- Even when the laryngoscope blade has been inserted too deeply, inexperienced clinicians will sometimes try to displace the larynx anteriorly to look for the vocal cord in the proximal esophagus without recognizing that an esophageal laryngoscopy has been performed.
- Thus, the recognition of the posterior cartilage and interarytenoid notch as the anatomical distinctions between the larynx and esophagus is important.
In addition to the recognition of the posterior anatomical landmarks of the larynx, novice clinicians should progressively visualize the anatomical landmarks during laryngoscopy. Proximal esophagus visualization can be prevented only if the clinician performs intubation by sequentially confirming that they have identified the epiglottis, posterior cartilage, and interarytenoid notch while advancing the laryngoscope and exposing the vocal cords.
- The esophagus is a cylindrical tube with no surrounding structures.
- It is located immediately posteriorly to the larynx, and its color is similar to that of the larynx, which easily causes novice clinicians to confuse it with the latter structure.
- The esophageal surface of the larynx is distinguishable from the larynx because it is convex posteriorly in both the sagittal and transverse planes.
However, considering that rapid identification of the differences between the esophagus and larynx based on the shape is difficult when any laryngeal landmark is not confirmed, clinicians should remove the laryngoscope and advance it again while sequentially confirming the landmarks.
The incoming interns who participated in the study received traditional training on how to perform intubation using mainly a manikin, and some interns received intubation training during their clerkship period. In such traditional teaching settings, only the trainee can see the larynx during laryngoscopy, and the instructor can only provide limited direct and subtle feedback.
However, during video laryngoscopy, laryngoscopic images are displayed on the monitor via a video system mounted on the blade. These images are shared with the instructor, thus eliminating the aforementioned drawback of traditional training. Training novice clinicians using video laryngoscopy enhances their recognition of the airway anatomy and skills in handling standard Macintosh laryngoscopes.
- The additional advantages of the training based on video laryngoscopy include the increased success rate, reduced TSI, and better learning curve.
- Accordingly, this approach is highlighted as an educational tool to augment training using a manikin.
- Thus, video-based laryngoscopy is believed to be an excellent approach to improving the novice clinicians’ recognition of the airway landmarks and training them on progressive visualization.
This study has several limitations to consider when interpreting the results. First, the participants’ past experiences with regard to the use of size 3 and 4 curved blades were not examined. We could not survey how many times participants had previously used each blade, because they did not remember the number of experiences owing to the similar shape of the blades.
- Hence, the present findings may have been biased because the participants may have more experience with the use of size 3 than size 4 curved blades.
- However, all participants had weak intubation experience before the trial, which can limit the effect of this methodological weakness.
- In addition, if the participants clearly recognized the upper airway anatomy and sequentially confirmed the landmarks like an experienced clinician, no significant differences in intubation performance would have been observed regardless of the experience with each blade size owing to the identical laryngoscopic approach.
Second, this study used only 1 manikin, which is not a perfect substitute for humans. The size and shape of a manikin model also does not represent those of all clinical encounters in emergency situations, although we used the best available manikin, which was already evaluated and had also been used in the previous tracheal intubation-related studies.
- Different results may have been obtained if the tracheal intubation was performed on other manikins or human patients.
- However, this is a kind of exploratory study proposing a hypothesis of whether the size of the curved blade laryngoscope affects the outcomes of tracheal intubation performed by novice clinicians in a controlled setting, where the only difference between groups is the blade size.
Thus, we chose 1 manikin and considered it to be adequate for the study on the tracheal intubation through appropriate anatomical recognition of the upper airway. Nevertheless, there might be limitations in generalizing the results to the general patient population, because we used only 1 manikin.
- Further studies with patients in real situations are needed.
- Third, this study did not use a crossover design.
- It would be the best study design, considering that it minimizes the potential for confounding because each participant serves as his or her own control.
- However, because this study was conducted within a 1-day boot camp dealing with many procedures and skills, we could not choose a crossover study design considering the washout period due to a time constraint.
Although it is not a crossover study, as an exploratory study, a randomized manikin study with a parallel design would be desirable to investigate the effect of the curved blade size on the outcomes of tracheal intubation in a controlled setting. Fourth, all participants were incoming interns of a medical center in an Asian country.
The intubation performance of novice clinicians from other countries may not be affected even when they use a size 4 curved blade. Orotracheal intubation may not even be an essential skill for such novice clinicians as those enrolled in this study. Thus, the generalization of the study findings to other populations would be difficult.
However, this study demonstrated that novice clinicians may not recognize the importance of anatomical landmarks and progressive visualization, which are critical in tracheal intubation, thus suggesting the need to address these issues during training.
How do I choose ETT size for neonates?
CONCLUSION – The age-based formula presented by Cole has long been used to select the appropriate ETT size in children. This formula is suitable for uncuffed ETTs; however, recent changes in the understanding of pediatric airway anatomy, redefined the use of cuffed ETTs.
Cuffed ETTs can reduce the number of endotracheal intubation attempts, and if cuff pressure can be maintained within a safe range, the risk of airway damage may not increase, compared to an endotracheal tube without a cuff. When estimating cuffed ETT size using an age-based formula, Duracher’s formula is more accurate.
However, a tube 0.5 mm larger or smaller than the calculated size should always be possible to use. Because age-based formulas in children are not always accurate, various methods for estimating ETT size, such as chest radiography, ultrasound, and three-dimensional airway models, have been investigated.
How is ETT size calculated in NICU?
The 7th edition Neonatal Resuscitation Program recommends using the gestation-based ‘initial endotracheal tube insertion depth’ table or measuring the newborn’s nasal–tragus length and adding 1 cm to determine the correct ET insertion depth.
What is the cuff size for an infant intubation?
Select an uncuffed tube with an internal diameter of 3.5 mm for infants up to 1 year of age. A cuffed ETT with an internal diameter of 3.0 mm may be used for infants more than 3.5 kg. and
How do I choose a laryngoscope blade?
The blade length excluding the base is measured by placing the proximal blade at the child’s upper incisor teeth with the blade tip extending to the angle of the mandible. If the blade tip is within 1 cm proximal or distal to the angle of the mandible, it is an appropriate blade length for intubation.
How do I choose a blade length?
Cart ( 0 products) Cart (1 product) – Total products Total shipping To be determined Total (tax incl.) Continue shopping Shopping cart Blog > How to choose your straight sword blade length Articles déc.28, 2010 Beginners and newbies will prefer to choose a short blade because it will be easier to mainpulate. But most of the time to choose a blade length, people measure their arm (from wrist to shoulder) and add 5 cm. Then when you stand up start a serie, holding your sword at the handle, the blade will exceed from your shoulder of about 5cm.
What is the best laryngoscope blade for infants?
Results – A total of 50 children were enrolled and completed the study ( Fig.2). Patient characteristics and surgical procedures for the two groups were comparable ( Table 1). The laryngoscopist experienced no difficulty in visualizing the larynx in any child. Table 1. Patient characteristics. Age is median (range) and weight is mean ( sd )
| Miller | Macintosh | |
|---|---|---|
| Age (months) | 14 (5–23) | 15 (4–23) |
| Weight (kg) | 9.9 (1.7) | 10.7 (1.8) |
| Sex (male/female) | 19/6 | 16/9 |
| Surgery | ||
| Otolaryngology | 15 | 9 |
| Urology/gen. surgery | 10 | 9 |
| Dental/eye/others | 0 | 7 |
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Table 1. Patient characteristics. Age is median (range) and weight is mean ( sd )
| Miller | Macintosh | |
|---|---|---|
| Age (months) | 14 (5–23) | 15 (4–23) |
| Weight (kg) | 9.9 (1.7) | 10.7 (1.8) |
| Sex (male/female) | 19/6 | 16/9 |
| Surgery | ||
| Otolaryngology | 15 | 9 |
| Urology/gen. surgery | 10 | 9 |
| Dental/eye/others | 0 | 7 |
table>
Fig 2. Consort diagram. The POGO scores for the Miller size 1 blade lifting the epiglottis and the MAC size 1 blade lifting the tongue base were similar ( Fig.3). The POGO scores for the Miller blade lifting the epiglottis and the tongue base were also similar ( Fig.3).
- In contrast, the POGO scores for the MAC blade lifting the tongue base were greater than the scores lifting the epiglottis ( Fig.3) ( P =0.0004).
- The laryngeal views in five children were poor (POGO score ≤25) ( Fig.3).
- In one child in whom the Miller blade was used to lift the tongue base, the epiglottis could not be displaced from view.
In two children in whom the MAC blade was used to lift the epiglottis, the curve of the MAC blade obstructed the laryngeal view. In one child in whom the Miller blade was used to lift the epiglottis and in another in whom the MAC blade was used to lift the tongue base, the views were poor.
- Post hoc, three additional analyses were performed.
- In the first, the frequency of POGO scores ≥80 was compared: Miller blade lifting the epiglottis 16/25; Miller blade lifting the tongue base17/25; MAC blade lifting the tongue base 21/25; MAC blade lifting the epiglottis 14/25 ( P =NS).
- In the second, the POGO scores=100 were 9/25; 6/25; 11/25; 4/25, respectively ( P =NS).
In the third, the POGO scores in infants Fig 3. The POGO scores for the Miller and MAC blade views for each child are displayed. The solid symbols are the scores lifting the epiglottis and the open symbols are the scores lifting the tongue base. *The mean POGO scores for lifting the epiglottis with the MAC blade, 67.2 (56.1–78.3), were significantly less than those for lifting the tongue base, 84.4 (76.5–92.3) ( P =0.0004).
The mean POGO scores for lifting the epiglottis with the Miller blade, 78.4 (70.0–87.0), did not differ from those lifting the tongue base, 76 (67.1–84.9). Data are means (95% CI). The times to first and second laryngoscopies and to tracheal intubation were similar between the two blades ( Table 2). The minimum S a O 2 values during laryngoscopy with the two blades were similar.
Heart rate increased ∼10% and systolic arterial pressure decreased ∼10% with both blades during the 5 min study. There were no episodes of bradycardia or arrhythmias. Table 2. Procedural times and S a O 2 measurements. Data are summarized as medians (ranges).
| Miller | Macintosh | |
|---|---|---|
| Time to first laryngoscopy (s) | 180 (180–300) | 180 (180–300) |
| Time to second laryngoscopy (s) | 20 (10–30) | 30 (10–60) |
| Time to tracheal intubation (s) | 20 (10–50) | 30 (10–40) |
| Minimum S a O 2 during the study | 94 (93–97) | 95 (92–98) |
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Table 2. Procedural times and S a O 2 measurements. Data are summarized as medians (ranges). Time to first laryngoscopy was the time from administration of rocuronium until laryngoscopy. Time to second laryngoscopy was the time interval between the first and second laryngoscopy. Time to tracheal intubation was the time interval between the second laryngoscopy and tracheal intubation
| Miller | Macintosh | |
|---|---|---|
| Time to first laryngoscopy (s) | 180 (180–300) | 180 (180–300) |
| Time to second laryngoscopy (s) | 20 (10–30) | 30 (10–60) |
| Time to tracheal intubation (s) | 20 (10–50) | 30 (10–40) |
| Minimum S a O 2 during the study | 94 (93–97) | 95 (92–98) |
table>
The blade assigned to each child was used to successfully complete the laryngoscopy and tracheal intubation in every child. No blades were exchanged or replaced. There were no complications associated with participating in this investigation.
Which laryngoscope is used for neonates?
Neonatal Laryngoscope | A neonatal laryngoscope for. Background Each year in developed countries worldwide, more than 14 million babies are born preterm (The Lancet: Vol 379 June 9, 2012) with approximately 6-7% (or close to 1 million) requiring intubation.
Currently neonatal intubation is performed using a miniature adult laryngoscope which is marketed as a pediatric laryngoscope. However, the miniature adult laryngoscope is not optimally designed for neonatal anatomy, which can result in challenges to properly insert the device, obstructed view of the larynx and injury to the patient.
There is currently no laryngoscope exclusively designed for neonates themselves. Technology Overview A neonatal laryngoscope has been designed specifically for the anatomy of neonates, making intubation significantly simpler and more efficient. Importantly, the neonatal laryngoscope addresses the need to reduce the trauma associated with the existing laryngoscopes in the market (Figure 1).
• Eliminates the chances of trauma to the upper lip and jaw caused by the present laryngoscope blade – an essential advantage • Less bulky than the current laryngoscope making it easier for the physician to handle • The ergonomics are such that the device does not require health care providers intubating the newborn to learn a new technique but facilitates the intubation procedure • Provides unobstructed vision of the larynx (opening of the windpipe) against the partial obstructed vision of current laryngoscope
• Utility for clinical trials and patient care: safe and effective intubation of neonates : Neonatal Laryngoscope | A neonatal laryngoscope for.
What blade for infant intubation?
The straight Miller laryngoscope blade is traditionally recommended for intubation in infants, due to the large size and flexibility of the infant epiglottis.
What blade is on a child laryngoscope?
It is an instrument used for intubation and direct laryngoscopy. It consists of two parts – the blade and the handle. The handle contains the battery container, which acts as an energy source for the light source. The blades are of two varieties: 1) Straight blade 2) Curved blade Straight blade is used to depress the tongue whereas the curved blade pushes the epiglottis to one side to visualize the glottis. In infants, the straight blade is preferred whereas in older children (more than 8 years), the curved blade is preferred. There are various sizes of the laryngoscope available in different numbers e.g.0,1,2,3,4. The numbers increases with the size of the blade. Care has to be taken while doing laryngoscopy to prevent injury to the oral structures especially dislocation and aspiration of the tooth. Maximum trauma is caused by utilization of upper anterior teeth or gums as a fulcrum point. Laryngoscopy is also used to pick up any foreign body in the larynx, for passing a bronchoscope / esophagoscope and also for throat packing. The various parts of the laryngoscope are sterilized separately. The blade is washed under running tap water with detergent giving special attention to cleaning around the light bulb and then boiled/autoclaved/gas sterilized or chemically sterilized with alcohol/glutaraldehyde.What size laryngeal mask for neonates?
RANGE, SIZES, AND INSERTION TECHNIQUES OF THE LMA – The standard version, made of medical grade silicone, consists of an oval shaped mask with an inflatable outer rim; a wide bore airway tube, which originates from the back plate, is joined at the proximal end with a 15 mm standard connector.
- The two aperture bars in the middle of the mask lumen, opposite to the distal end of the airway tube, are intended to prevent obstruction of the tube by the epiglottis.
- The black line running along the shaft helps to detect any subsequent rotation of the mask on the tube axis (fig 1).
- Figure 1 Basic laryngeal mask airway design.
Reproduced by permission from Dr A I J Brain. Laryngeal mask instructor manual, 2000. Courtesy of The Laryngeal Mask Company Limited. Although alternative insertion techniques have been reported, 10 that described by Brain 8 is the one that we favour. This technique mimics the action of swallowing a bolus of food with the index finger pressing the mask against the hard palate, and posterior pharyngeal wall mimics the action of the tongue.
- Use the correct size of LMA for the patient. Size 1 is suitable for neonates weighing 2.5–5 kg.11 It has been postulated that a smaller size (0.5) could be useful in preterm newborns. However, there are reports of successful use of size 1 in preterm neonates weighing 0.8–1.5 kg.12– 15
- Fully deflate the cuff as described in the manual, and lubricate the back of the mask tip (for neonates in the labour ward, lubrication may not be necessary, as oral and pharyngeal secretions may reproduce this function).
- Press (flatten) the tip of the LMA against the hard palate. During this manoeuvre, the operator should grasp the LMA like a pen with the index finger at the junction between the mask and the distal end of the airway tube.
- Gently advance the LMA with one single movement, applying continuous pressure against the palatopharyngeal curvature with the index finger. The vector of the force applied must be directed cranially and not caudally.
- Continue pushing the LMA against the soft palate so that the cuff passes along the posterior pharyngeal wall and the tip locates itself in the hypopharynx—that is, it cannot be pushed further inwards.
- Inflate the mask to the minimum air volume necessary to establish an adequate seal. The maximum recommended volume for each size is rarely required. Do not hold the shaft of the LMA during cuff inflation, as the shaft may be observed to move outwards during cuff inflation allowing correct positioning.
- Connect the proximal end of the airway tube to a device (bag, ventilator) for PPV.
- Correct LMA positioning (fig 2) can be evaluated by observing synchronous movements of the chest and by neck auscultation.
Figure 2 Demonstration of correct anatomical positioning of the laryngeal mask airway cuff around laryngeal inlet. Reproduced by permission from Dr A I J Brain. Laryngeal mask instructor manual, 2000. Courtesy of The Laryngeal Mask Company Limited. The most common problem encountered during this manoeuvre is obstruction at the base of the tongue.
In this case, the mask must be removed and the procedure reviewed in all its phases. Failure to follow the recommended insertion technique strictly may result in malposition of the LMA. Specifically, the epiglottis may be “downfolded”, the mask lumen may not be correctly aligned with the laryngeal inlet, or the cuff may fold inwards or lie too high in the pharynx.16– 18 After correct insertion and use, the LMA is left in place, until spontaneously ejected by the patient.
The overall incidence of complications after removal of the LMA is about 10–13%, including coughing, laryngospasm, retching, breath holding, vomiting, stridor, desaturation, and excessive salivation.19 Many of these complications are caused by overinflation of the LMA cuff and inadequate analgesia.
A survey of almost 12 000 patients of all ages managed with the LMA over a two year period reported only 18 (0.15%) critical incidents related to airway management, and none required intensive care management.20 Since its first commercialisation in the United Kingdom in 1988 and in the United States in 1991, the LMA has gained widespread popularity, initially in adult and then in paediatric patients.16– 19 The American Society of Anaesthesiologists has included the LMA in the algorithm for difficult airway management.21 Over the last 10 years, the original prototype, LMA-Classic, which has been used in thousands/millions of patients, has been modified and improved.
There are currently five different versions of the LMA, although only the classic model is currently available in a neonatal size.19, 22– 24 LMA-ProSeal is shortly to be made available in paediatric sizes and awaits evaluation (A I J Brain, personal communication).
What size is a Mac 4 blade?
4074; MacIntosh; Size 4, Large Adult; Overall Length:159 mm; Inside Base to Tip:137 mm.
Which laryngoscope blade is preferred for intubating infants and children?
An infant’s airway: A difficult terrain And now, by all the words the preacher saith,I know that time for me, is but a breath,And all of living but a passing sigh,A little wind that stirs the calm of death. Hakim Omar Khayam (1048-1131 CE). In this issue of the journal Golzari et al, report the successful anesthetic management of a 4 months old infant undergoing vallecular cyst excision. An inhalational induction with sevoflurane was initiated followed by succinylcholine and endotracheal intubation. There are some points that need scientific clarification which would finally unveil this issue as to whether this case could have been managed otherwise or not. After the loss of skeletal muscle tone, a trial laryngoscopy was performed and a cyst visualized at the base of the tongue. However, the epiglottis was not seen meaning thereby that a Cormak–Lehane grade was encountered. Despite the fact that under such circumstances, a difficult intubation drill is advocated, the authors decided to give succinylcholine. What prompted them to use succinylcholine when they report an adequate skeletal muscle relaxation and a gentle laryngoscopy under an umbrella of high concentration of sevoflurane? If they could conduct gentle laryngoscopy and at the same time navigated the blade of the laryngoscope as far as to get a sneak at the base of the tongue and confirm that a cyst was residing at the vallecular without precipitating a laryngospasm which is so common in infants, a rational approach would have been to advance the blade a little farther with an intention of loading up the epiglottis with the tip of the blade thereby unfolding the entrance of the larynx and conducted intubation. Perhaps the use of succinylcholine was not justified as if could have ended up in a difficult mask ventilation and thus ushered in disastrous complications. When the authors could figure out the cyst at the vallecular region during their initial laryngoscopy, it is highly possible that the cyst had pushed forward the epiglottis obscuring its view, and a gentle advancement of the blade would have unfolded the entrance of the laryngeal inlet without necessitating the administration of succinylcholine. From the case report, it cannot be discerned whether a straight Miller blade or a Macintosh blade was used. The authors seemingly avoided the midline terrain during laryngoscopy and managed to intubate the patient by applying a cricoid pressure. Intuitively, we can assume that the authors used a straight Miller blade and advanced it to avoid the midline structures superior to the vallecula. The charade worked well and they could intubate the infant. The Miller straight laryngoscope blade is regarded as the preferred blade to expose the laryngeal inlet in infants and children. However, there is a dearth of evidence to support the superiority of the Miller blade in exposing the laryngeal inlet compared to the Macintosh blade in infants. Likewise, Passi et al, found similar laryngeal views with the Miller blade lifting the epiglottis and the Macintosh blade lifting the base of the tongue. The paraglossal intubation using a straight blade can be helpful in micrognathia. This approach wherein the laryngoscope blade is advanced in the space between the tongue and the lateral pharyngeal wall thus bypassing the tongue and shortening the distance to access the larynx could have been of value in this particular case as it would have obviated an impingement of the cyst in contrast to using the Miller or the Macintosh blade cruising the classical midline terrain traversing the tongue, its base, the vallecula and the epiglottis. The cyst in this particular case might have pushed forward the epiglottis obscuring its view and this view was exactly what the authors could capture during gentle laryngoscopy. The authors have erroneously used the phraseology, “cricoid pressure” while attempting intubation. Cricoid pressure was initially described by Sellick as a method to protect the patients from regurgitation of gastric contents during intubation, and this maneuver was not at all intended to facilitate intubation. The authors state that a cricoid pressure was applied along with laryngeal pressure which helped them in visualizing the laryngeal inlet. It could be construed that the assistant applied external laryngeal pressure to better visualize the glottis, or else perhaps applied a backward, upward, rightward pressure (BURP), and initially forwarded by Knill. The BURP maneuver, however, should not be combined with the Sellick maneuver (cricoid compression) because it would make the performance of the laryngoscopy difficult and visualization of the vocal cords highly impossible. At times, anesthesiologists use different combinations such as applying external laryngeal pressure and positioning of the head and neck to execute intubation in difficult cases but the cricoid pressure has never been mentioned to provide a better look of the glottis and to work as a substitute for BURP. Cricoid pressure and BURP are totally different maneuvers and are exclusively and explicitly used for altogether different targets and different goals and are not to be confused. Finally, I may conclude that before an anesthetic is administered, it is of paramount importance to correctly diagnose the potential airway problems so as to choose the alternative modalities of airway management.1. Golzari SE, Khan ZH, Ghabili K, Hosseinzadeh H, Soleimanpour H, Azarfarin R, et al. Contributions of medieval islamic physicians to the history of tracheostomy. Anesth Analg.2013; 116 :1123–32.2. Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anesthesia.1984; 39 :1105–11.3. Miller RA. A new laryngoscope for intubation of infants. Anesthesiology.1946; 7 :205.4. Jones RM, Jones PL, Gildersleve CD, Hall JE, Harding LJ, Chawathe MS. The Cardiff paediatric laryngoscope blade: A comparison with the Miller size 1 and Macintosh size 2 laryngoscope blades. Anesthesia.2004; 59 :1016–9.5. Passi Y, Sathyamoorthy M, Lerman J, Heard C, Marino M. Comparison of the laryngoscopy views with the size 1 Miller and Macintosh laryngoscope blades lifting the epiglottis or the base of the tongue in infants and children <2 yr of age. Br J Anaesth.2014; 113 :869–74.6. Bonfils P. Difficult tracheal intubation in Pierre Robin children, a new method: The retromolar route. Anesthesia.1983; 32 :363–7.7. Sellick BA. Cricoid pressure to control regurgitation of stomach contents during induction of anesthesia. Lancet.1961; 2 :404–6.8. Knill RL. Difficult laryngoscopy made easy with a "BURP" Can J Anaesth.1993; 40 :279–82.9. Snider DD, Clarke D, Finucane BT. The "BURP" maneuver worsens the glottic view when applied in combination with cricoid pressure. Can J Anaesth.2005; 52 :100–4.10. Khan ZH, editor. Airway Management.1st ed. Switzerland: Springer International Publishing; 2014. Airway management: A critical appraisal; pp.15–32. : An infant's airway: A difficult terrain
What laryngoscope blade to use?
Comparison of the Laryngoscopic View using Macintosh and Miller Blades in Children Less than Four Years Old Received 2020 Feb 22; Accepted 2020 Aug 28. ©Carol Davila University Press This article is distributed under the terms of the Creative Commons Attribution License (), which permits unrestricted use and redistribution provided that the original author and source are credited.
This study aimed to compare Miller and Macintosh laryngoscopes in zero to 4-year-old children. A total of 72 children with a score of I and II, according to the American Society of Anesthesiologists (ASA) physical status classification, who were candidates for elective surgery with general anesthesia and tracheal intubation were enrolled in the study.
The children were divided into two equal groups (36 persons) according to used laryngoscope: Miller laryngoscope (group 1) and Macintosh laryngoscope (group 2). Observations and all laryngoscopies were performed by a single experienced anesthesiologist.
Heart rate, systolic blood pressure, non-invasive arterial blood pressure, and hemoglobin saturation were measured and recorded. The number of endotracheal intubation attempts and complications were also recorded for both groups. In terms of gender, the first group consisted of 88.9% boys and 11.1% girls, and the second group consisted of 66.6% boys and 33.3% girls (p-value=0.05).
The mean age was 16.7 months in the first group and 17.7 months in the second group (p-value=0.5). The mean weight of the children was 16988.5 g and 16300 g in the Miller and Macintosh groups, respectively (p-value=0.9). Regarding the Cormack-Lehane classification system, 5 patients were classified as grade 1 (13.9%), 14 patients as grade 2 (38.9%), 15 patients as grade 3 (41.7%), and 2 patients as grade 4 (5.6%) in the Macintosh group.
- In contrast, in the Miller group, 5 patients were classified as grade 1 (13.9%), 27 patients as grade 2 (75%), and 4 patients as grade 3 (11.1%) (p-value=0.004).
- These results can provide more data about the tracheal intubation method with the Macintosh and Miller laryngoscopes, the ease of intubation, and the best laryngoscopic view with each blade.
Keywords: Laryngoscopes, Miller blade, Macintosh blade, children, surgery Proper airway management by laryngoscopy and tracheal intubation is essential, Laryngoscopy and endotracheal intubation can cause pain and severe sympathoadrenal response, which can result in increased plasma concentrations of catecholamines, blood pressure, heart rate, intracranial pressure, and intraocular pressure, as well as impaired heart rhythm.
These changes usually appear within seconds, while sinus tachycardia peaks within two minutes and lasts for five minutes. These variations may be well tolerated in young people without underlying diseases, but they can cause serious complications in patients with cardiovascular diseases, hypertension, high intracranial pressure, and cerebrovascular diseases.
Moreover, due to the increased need for oxygen, they can lead to myocardial ischemia, myocardial infarction, cardiac arrhythmia, stroke, and increased morbidity and mortality, A laryngoscope is a device for observing the larynx, the vocal cords, and the duct between them, which has various types.
A laryngoscope consists of a long handle and a blade with a small light source at the top. The laryngoscope blade’s design has many forms, and the two most commonly used blades are the Macintosh and Miller blades, which are curved and straight, respectively. The Macintosh blade is easier to operate, while the Miller blade provides a better view of the vocal cords.
The use of each of these blades depends on the habit and experience of anesthesiologists, In laryngoscopy with a Macintosh blade, the blade enters the vallecula, and the hyoepiglottic ligament is elevated without affecting the epiglottis, requiring the maximum extension of the neck while the tongue is pulled leftward and then subjected to a strong force pulling upward.
- However, the blade of the Miller laryngoscope is straight, and the epiglottis is lifted during laryngoscopy.
- In most cases, when the Macintosh laryngoscope cannot be used, the Miller laryngoscope is utilized because it requires less force and less neck extension.
- It is used in people with irregular teeth, especially those with missing right upper teeth,
The Miller blade is straight without any curvature, and due to the anatomy of the mouth and tongue and the large epiglottis in children, the Miller blade provides a clearer view of the larynx inlet, Since children are sensitive and laryngoscopy is a difficult and painful action, the purpose of this study was to select a blade that would minimize injury to the patient.
- Therefore, this study was designed to compare two Macintosh and Miller blades for laryngoscopy in children less than 4-year-old.
- A total of 72 children with a score of I and II, according to the American Society of Anesthesiologists (ASA) physical status classification, who were candidates for elective surgery with general anesthesia requiring intubation were enrolled in the study after obtaining written consent from their parents.
Exclusion criteria were abnormal airway anatomy, history of active respiratory infections or cold in the past three weeks, history of chronic respiratory asthma, and allergies. The children were randomly divided into two groups. Laryngoscopy and intubation were performed with a Miller blade (group I) and with a Macintosh blade (group II).
In both groups, children received oral premedication: midazolam 0.5 mg/kg and ketamine 2.5 mg/kg. Half an hour after sedation, EMLA anesthetic ointment was applied and venipuncture was performed with a 22-gauge angiocath. After entering the operating room, the standard monitoring system for pulse oximetry, electrocardiogram (ECG), and non-invasive blood pressure (NIBP) was installed.
Anesthesia was induced through inhalation of sevoflurane (8%) and 100% oxygen at a gas flow rate of 3 L/min. Laryngoscopy and endotracheal intubation were performed after appropriate anesthesia and injection of 5 mg/kg sodium thiopental and 1 μg/kg fentanyl.
• grade 1 – full view of glottis; • grade 2 – only posterior extremity of glottis can be seen; • grade 3 – only epiglottis can be seen; • grade 4 – neither glottis nor epiglottis can be seen.
The larynx was observed by positioning the head and using external pressure on the larynx to obtain the best view. In this study, the time interval between laryngoscopy and endotracheal intubation, heart rate, systolic blood pressure, non-invasive arterial blood pressure, and hemoglobin saturation were measured and the number of endotracheal intubation attempts and complications were recorded for both groups.
| Variable | Miller | Macintosh | p-value* | ||
|---|---|---|---|---|---|
| Gender | Male | Number | 32 | 30 | 0.7 |
| Percent | 88.9 | 83.33 | |||
| Female | Number | 4 | 6 | ||
| Percent | 11.1 | 16.67 | |||
| Age Mean ± SD (months) | 16.75 ± 4.99 | 17.78 ± 9.19 | 0.5 | ||
| Weight Mean ± SD (gram) | 16988.57 ± 2431.99 | 16300 ± 4950.04 | 0.9 |
A comparison of the mean heart rate in the two groups showed that the p-value was 0.4 before laryngoscopy and 0.06 after laryngoscopy. In the Miller group, the heart rate was 131.4 before laryngoscopy and 137.4 after laryngoscopy (p-value=0.04). In the Macintosh group, the heart rate was 124.2 before laryngoscopy and 127.9 after laryngoscopy (p-value=0.047).
| Variable | Group | Mean ± SD | p-value* |
|---|---|---|---|
| Mean systolic/diastolic pressure before laryngoscopy | Miller | 131.92±17.12 | 0.4 |
| Macintosh | 124.28±17.63 | ||
| Mean systolic/diastolic pressure after laryngoscopy | Miller | 137.44±19.66 | 0.06 |
| Macintosh | 127.97±18.9 |
The mean oxygen saturation (SaO2) in minutes 1, 2, 3, 4, and 5 in the Miller and Macintosh group are shown in, According to the results, there was a significant difference between the two groups in terms of SaO2 only at minute 4, while the difference was not significant at other times. Mean SaO2 at different times in the Miller and Macintosh groups.
| Variable | Minute | Group | Mean ± SD | p-value* |
|---|---|---|---|---|
| SaO 2 | 1 | Miller | 99.81±0.47 | 0.5 |
| Macintosh | 99.72±0.61 | |||
| 2 | Miller | 99.75±0.60 | 0.2 | |
| Macintosh | 99.56±0.69 | |||
| 3 | Miller | 97.44±1.23 | 0.6 | |
| Macintosh | 97.56±0.97 | |||
| 4 | Miller | 98.81±0.82 | 0.003 | |
| Macintosh | 99.33±0.63 | |||
| 5 | Miller | 99.64±0.49 | 0.3 | |
| Macintosh | 99.75±0.50 |
The mean saturation decrease was 1.26 in the Miller group and 1.54 in the Macintosh group (p=0.3). Regarding the Cormack-Lehane classification system, 5 patients were classified as grade 1 (13.9%), 14 patients as grade 2 (38.9%), 15 patients as grade 3 (41.7%), and 2 patients as grade 4 (5.6%) in the Macintosh group. In contrast, 5 patients were classified as grade 1 (13.9%), 27 patients as grade 2 (75%), and 4 patients as grade 3 (11.1%) in the Miller group (p-value=0.004). Management of airways during general anesthesia is the responsibility of anesthesiologists. Various methods, such as face mask, laryngeal mask, and endotracheal intubation, are used in this regard, Endotracheal intubation requires the use of a laryngoscope, which is available with different blades such as Macintosh and Miller, The aim of all of these devices is to provide a convenient view of the patient’s larynx for easy intubation, In a study conducted in India in 2014, Kundu et al. compared the Miller and Macintosh blades in children under 5 months under general anesthesia in terms of laryngoscopic view and ease and success of intubation. The authors found a similar view of the glottis in 43% of cases and a better view in 29% and 28% of cases when using the Miller and Macintosh blades, respectively. In addition, laryngoscopy was easily performed in 54% of cases, whereas it was performed difficultly in 27 children with both blades, in 15 children with the Miller blade, and in 13 children with the Macintosh blade, There was a significant difference between the two groups in the mean heart rate at minute 3 (p-value=0.03), the mean systolic/diastolic pressure at all minutes, and the mean SaO2 at minute 4 (p-value=0.003). In a study by Bhardwaj conducted in 2013 to evaluate cervical spine motion with a Macintosh laryngoscope and a Trueview laryngoscope, the authors found that the latter offered a better laryngoscopic view of the glottis and less cervical spine motion, In a study by Lu Yi that compared the Airtraq laryngoscope with the conventional Macintosh laryngoscope, the intubation time was reduced using the former (p<0.0001). Intubation was performed by both experienced and novice anesthesiologists (relative risk 1.25, p-value=0.07); therefore, the Airtraq laryngoscope facilitates and accelerates intubation, Bein et al. compared the conventional curved blade laryngoscope and GlideScope laryngoscope in difficult airways and showed that the latter was significantly better than straight laryngoscope, In a study from Singapore, Lye Sti compared endotracheal intubation with Macintosh laryngoscopy and indirect laryngoscopy and showed that the rate of successful intubation with indirect laryngoscopy (85%) was higher than Macintosh laryngoscopy (69%), In the present study, there was no significant difference between the two groups regarding the demographic variables (age, gender, and weight). Therefore, it seems that randomization and matching were appropriate, and there were no confounding factors in this regard in the study. Also, there was no significant difference in the mean blood pressure before and after laryngoscopy between the groups. There was a significant increase in the heart rate before and after laryngoscopy due to stress in response to laryngoscopy. There was a statistically significant difference in the heart rate increase before and after laryngoscopy in the Miller group. Although changes in the heart rate were statistically significant, the increase in the heart rate was clinically less than 10% in the two groups and, therefore, did not require any special treatment. There was no decrease in saturation in neither of the groups, and it seems that the laryngoscopy blades had no effect on the oxygen saturation of hemoglobin. The Cormack-Lehane classification of the laryngoscopic view was the most important variable in this study. In the Macintosh group, 5 patients were classified as grade 1, 14 patients as grade 2, 15 patients as grade 3, and 2 patients as grade 4. In contrast, in the Miller group, 5 patients were classified as grade 1, 27 patients as grade 2, and 4 patients as grade 3 (p-value=0.004). In general, the Cormack-Lehane system of the Miller blade was better than the Macintosh blade, giving a better laryngoscopic view. One finding of interest in this study is that older children had a better Cormack-Lehane grade. It seems that the laryngoscopic view improves as the age increases, and younger age is associated with a worse laryngoscopic view. This can be justified by the anatomy of the airway in children - their larynx is located anterior and superior, and their epiglottis is larger. As a result, there is a direct relationship between the improved laryngoscopic view and the Cormack-Lehane grade with age. However, there was no significant relationship between the two groups in terms of gender, and it seems that gender has no effect on the Cormack-Lehane grade. The authors declare that there is no conflict of interest.1. Magill I. Technique in endotracheal anaesthesia. British medical journal.1930; 2 (3645):817.2. Macintosh R. A new laryngoscope. Lancet.1943:205.3. Arino J.J., et al. Straight blades improve visualization of the larynx while curved blades increase ease of intubation: a comparison of the Macintosh, Miller, McCoy, Belscope and Lee-Fiberview blades. Canadian Journal of Anesthesia.2003; 50 (5):501.4. Ray D., et al. A comparison of McGrath and Macintosh laryngoscopes in novice users: a manikin study. Anaesthesia.2009; 64 (11):1207–1210.5. Orebaugh S.L., Bigeleisen P.E. Lippincott Williams & Wilkins; 2012. Atlas of airway management: techniques and tools.6. Benumof J. Conventional (laryngoscopic) orotracheal and nasotracheal intubation (single-lumen tube) Airway management. Principles and Practice.1996:261–276.7. Rubio F.Q., et al. Magill forceps: a vital forceps. Pediatric emergency care.1995; 11 (5):302–303.8. Suzuki A., et al. Use of a new curved forceps for McGrath MAC TM video laryngoscope to remove a foreign body causing airway obstruction. Saudi journal of anaesthesia.2013; 7 (3):360.9. Soroudi A., et al. Adult foreign body airway obstruction in the prehospital setting. Prehospital emergency care.2007; 11 (1):25–29.10. Koomson A.K., Lavoie J. Broken fragment from a Magill forceps in the airway of a neonate. Canadian Journal of Anesthesia.2005; 52 (10):1105–1106.11. Mattu A., et al. Lippincott Williams & Wilkins; 2012. Avoiding common errors in the emergency department.12. Asai T., et al. Comparison of two Macintosh laryngoscope blades in 300 patients. British journal of anaesthesia.2003; 90 (4):457–460.13. Smith C.E., et al. Evaluation of tracheal intubation difficulty in patients with cervical spine immobilization: fiberoptic (WuScope) versus conventional laryngoscopy. Anesthesiology.1999; 91 (5):1253–1259.14. Asai T., et al. Evaluation of the disposable Vital View™ laryngoscope: apparatus. Anaesthesia.2001; 56 (4):342–345.15. Bhardwaj N., et al. Assessment of cervical spine movement during laryngoscopy with Macintosh and Truview laryngoscopes. Journal of anaesthesiology, clinical pharmacology.2013; 29 (3):308.16. Lu Y., Jiang H., Zhu Y. Airtraq laryngoscope versus conventional Macintosh laryngoscope: a systematic review and meta-analysis. Anaesthesia.2011; 66 (12):1160–1167.17. Serocki G., et al. Management of the predicted difficult airway: a comparison of conventional blade laryngoscopy with video-assisted blade laryngoscopy and the GlideScope. European Journal of Anaesthesiology (EJA) 2010; 27 (1):24–30.18. Lye S.T., et al. Comparison of results from novice and trained personnel using the Macintosh Laryngoscope, Pentax AWS®, C-MACTM, and Bonfils Intubation Fibrescope: a manikin study. Singap Med J.2013; 54 :64–8. : Comparison of the Laryngoscopic View using Macintosh and Miller Blades in Children Less than Four Years Old
What type of laryngoscope blade is used to intubate an infant and newborn?
An infant’s airway: A difficult terrain And now, by all the words the preacher saith,I know that time for me, is but a breath,And all of living but a passing sigh,A little wind that stirs the calm of death. Hakim Omar Khayam (1048-1131 CE). In this issue of the journal Golzari et al, report the successful anesthetic management of a 4 months old infant undergoing vallecular cyst excision. An inhalational induction with sevoflurane was initiated followed by succinylcholine and endotracheal intubation. There are some points that need scientific clarification which would finally unveil this issue as to whether this case could have been managed otherwise or not. After the loss of skeletal muscle tone, a trial laryngoscopy was performed and a cyst visualized at the base of the tongue. However, the epiglottis was not seen meaning thereby that a Cormak–Lehane grade was encountered. Despite the fact that under such circumstances, a difficult intubation drill is advocated, the authors decided to give succinylcholine. What prompted them to use succinylcholine when they report an adequate skeletal muscle relaxation and a gentle laryngoscopy under an umbrella of high concentration of sevoflurane? If they could conduct gentle laryngoscopy and at the same time navigated the blade of the laryngoscope as far as to get a sneak at the base of the tongue and confirm that a cyst was residing at the vallecular without precipitating a laryngospasm which is so common in infants, a rational approach would have been to advance the blade a little farther with an intention of loading up the epiglottis with the tip of the blade thereby unfolding the entrance of the larynx and conducted intubation. Perhaps the use of succinylcholine was not justified as if could have ended up in a difficult mask ventilation and thus ushered in disastrous complications. When the authors could figure out the cyst at the vallecular region during their initial laryngoscopy, it is highly possible that the cyst had pushed forward the epiglottis obscuring its view, and a gentle advancement of the blade would have unfolded the entrance of the laryngeal inlet without necessitating the administration of succinylcholine. From the case report, it cannot be discerned whether a straight Miller blade or a Macintosh blade was used. The authors seemingly avoided the midline terrain during laryngoscopy and managed to intubate the patient by applying a cricoid pressure. Intuitively, we can assume that the authors used a straight Miller blade and advanced it to avoid the midline structures superior to the vallecula. The charade worked well and they could intubate the infant. The Miller straight laryngoscope blade is regarded as the preferred blade to expose the laryngeal inlet in infants and children. However, there is a dearth of evidence to support the superiority of the Miller blade in exposing the laryngeal inlet compared to the Macintosh blade in infants. Likewise, Passi et al, found similar laryngeal views with the Miller blade lifting the epiglottis and the Macintosh blade lifting the base of the tongue. The paraglossal intubation using a straight blade can be helpful in micrognathia. This approach wherein the laryngoscope blade is advanced in the space between the tongue and the lateral pharyngeal wall thus bypassing the tongue and shortening the distance to access the larynx could have been of value in this particular case as it would have obviated an impingement of the cyst in contrast to using the Miller or the Macintosh blade cruising the classical midline terrain traversing the tongue, its base, the vallecula and the epiglottis. The cyst in this particular case might have pushed forward the epiglottis obscuring its view and this view was exactly what the authors could capture during gentle laryngoscopy. The authors have erroneously used the phraseology, “cricoid pressure” while attempting intubation. Cricoid pressure was initially described by Sellick as a method to protect the patients from regurgitation of gastric contents during intubation, and this maneuver was not at all intended to facilitate intubation. The authors state that a cricoid pressure was applied along with laryngeal pressure which helped them in visualizing the laryngeal inlet. It could be construed that the assistant applied external laryngeal pressure to better visualize the glottis, or else perhaps applied a backward, upward, rightward pressure (BURP), and initially forwarded by Knill. The BURP maneuver, however, should not be combined with the Sellick maneuver (cricoid compression) because it would make the performance of the laryngoscopy difficult and visualization of the vocal cords highly impossible. At times, anesthesiologists use different combinations such as applying external laryngeal pressure and positioning of the head and neck to execute intubation in difficult cases but the cricoid pressure has never been mentioned to provide a better look of the glottis and to work as a substitute for BURP. Cricoid pressure and BURP are totally different maneuvers and are exclusively and explicitly used for altogether different targets and different goals and are not to be confused. Finally, I may conclude that before an anesthetic is administered, it is of paramount importance to correctly diagnose the potential airway problems so as to choose the alternative modalities of airway management.1. Golzari SE, Khan ZH, Ghabili K, Hosseinzadeh H, Soleimanpour H, Azarfarin R, et al. Contributions of medieval islamic physicians to the history of tracheostomy. Anesth Analg.2013; 116 :1123–32.2. Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anesthesia.1984; 39 :1105–11.3. Miller RA. A new laryngoscope for intubation of infants. Anesthesiology.1946; 7 :205.4. Jones RM, Jones PL, Gildersleve CD, Hall JE, Harding LJ, Chawathe MS. The Cardiff paediatric laryngoscope blade: A comparison with the Miller size 1 and Macintosh size 2 laryngoscope blades. Anesthesia.2004; 59 :1016–9.5. Passi Y, Sathyamoorthy M, Lerman J, Heard C, Marino M. Comparison of the laryngoscopy views with the size 1 Miller and Macintosh laryngoscope blades lifting the epiglottis or the base of the tongue in infants and children <2 yr of age. Br J Anaesth.2014; 113 :869–74.6. Bonfils P. Difficult tracheal intubation in Pierre Robin children, a new method: The retromolar route. Anesthesia.1983; 32 :363–7.7. Sellick BA. Cricoid pressure to control regurgitation of stomach contents during induction of anesthesia. Lancet.1961; 2 :404–6.8. Knill RL. Difficult laryngoscopy made easy with a "BURP" Can J Anaesth.1993; 40 :279–82.9. Snider DD, Clarke D, Finucane BT. The "BURP" maneuver worsens the glottic view when applied in combination with cricoid pressure. Can J Anaesth.2005; 52 :100–4.10. Khan ZH, editor. Airway Management.1st ed. Switzerland: Springer International Publishing; 2014. Airway management: A critical appraisal; pp.15–32. : An infant's airway: A difficult terrain
What is the cuff size for an infant intubation?
Select an uncuffed tube with an internal diameter of 3.5 mm for infants up to 1 year of age. A cuffed ETT with an internal diameter of 3.0 mm may be used for infants more than 3.5 kg. and
Which laryngoscope blade is usually used for infant intubation?
Miller vs Macintosh Size 0 Blades for Tracheal Intubation of Infants – Full Text View Miller blades are commonly used in pediatric anesthesia; however, there is less evidence-based information on the superiority of Miller blades in the visualization of the laryngeal inlet to Macintosh blades (1,2).
Therefore prospective randomized comparative studies on this field is required. Passi et al. (3) have demonstrated that, in 50 children aged between 6 months and 2 years, optimal laryngeal views could be obtained with either the Miller size 1 blades lifting the epiglottis or with Macintosh size 1 blades lifting the tongue base.
Another clinical trial compared the laryngoscopic views and tracheal intubation conditions with Macintosh and Miller blades in children from 1 month to 24 months. In this study involving 120 children, similar glottic views were obtained with both blades in 43% of the children while a better view was observed with the Miller blade in 29% of the children and with the Macintosh blade in 28% (4).
- Direct laryngoscopy for tracheal intubation in neonates is a procedure that mostly requires experience and constant practice (5).
- Neonates have a number of distinctive airway characteristics.
- These characteristics include the large tongue and head, the floppy, narrow U-shaped epiglottis, the larynx that is located more cephalad, and the vocal cords that are angled in an anterior-caudal position (4).
Therefore, straight laryngoscope blades are recommended for use in children and infants under 2 years of age. In neonatal tracheal intubations, Miller blade is the most frequently utilized blade (6). The reasons for this include the effective displacement of the tongue to the left of the laryngoscope with the Miller blade and the effective lifting of the long and floppy epiglottis during laryngoscopy (3).
- However, there is no prospective randomized and blinded comparative clinical study on this subject.
- The aim of the present study is to compare the glottic views with the size 0 Macintosh and Miller laryngoscope blades above and below the epiglottis.
- Methods: For the present study, the Ethics Committee approval was be obtained from the Faculty of Medicine, Istanbul Science University.
Written informed consent will be obtained from the parents of patients undergoing elective surgery. The study will involve ASA I or II patients under 1 month. Infants with a history of a difficult airway or diagnosed congenital syndrome, premature infants less than 37 weeks gestational age at birth, and those with acute or chronic pulmonary or neuromuscular diseases will be excluded from the study.
- Twenty five children undergoing elective surgery will be enrolled in the study.
- Infants will be randomized (using www.random.com) into two groups, the Miller and Macintosh blade groups, and whether the assigned blade is inserted above or below the epiglottis first, with allocation stored within sealed opaque envelopes until consent is obtained.
In a standard monitoring process, electrocardiogram (ECG), oxygen saturation, non-invasive blood pressure (NIBP), temperature and end-tidal CO2 pressure (EtCO2) will be monitored. Following the monitoring, anesthesia will be induced with 50% air, 50% oxygen and 8% sevoflurane.
- Once intravenous access is obtained, 0.5 mg/kg rocuronium will be administered.
- After preoxygenating with 100% oxygen and sevoflurane for 3 minutes, the assigned blade will be inserted into the mouth.
- All laryngoscopies will be performed by one of three paediatric anesthetists.
- The Miller blade will be inserted into the mouth at the right commissure and the tongue swept gently to the left.
The best laryngeal view will be achieved by optimizing the head position and applying external pressure to the larynx. As described by Passi et al. (3), two laryngeal views will be obtained with the same blade in each patient: lifting the epiglottis or the tongue base.
- The order of the views (lifting the epiglottis or the tongue base) will be determined by randomization immediately before laryngoscopy.
- The laryngeal views will be photographed each time by an anesthetist using a digital Olympus camera without using flash.
- The camera will be optimally positioned before laryngoscopy in order to capture the best possible views.
The photos will be reviewed by a blinded anesthetist using the percentage of glottic opening (POGO) score (7,8). This anesthetist will be blinded to the study hypothesis as well as which blade was used and where it was placed. We will photo the child’s name and the randomization code-blade type and which view was taken before and after each photo of the larynx.
- Then the photos will be uploaded and the number of the photo will be recorded in the study record for the child so we will know which photo corresponds to which blade and position for each child.
- After all the photos are taken, they will be randomized and given to the blinded observer to measure the vocal cord span.
: Miller vs Macintosh Size 0 Blades for Tracheal Intubation of Infants – Full Text View
What size tube for infant intubation?
Use 3.5 mm internal diameter cuffed endotracheal tube for children 1 to and a 3.0 mm internal diameter cuffed endotracheal tube for children