Jan 30, 2011 By age 10, all fingers are on the handle. No damage is caused to the airway from the larger blade. The theory behind it is that the larger blade of the Size 4, gives greater control of the tongue for all ages, and despite it's size, does not obsure views in any age.
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To compare the laryngoscopy view using two standard clinical devices, the Macintosh and Miller laryngoscopy blades, in infants between one day and two years of age.
Miller blades (straight blades) are more commonly used than MacIntosh blades (curved) in pediatric clinical practice in some institutions especially in infants. The anatomy of infant airway has traditionally been considered to lend itself to advantages of the Miller blade. Some argue that the Miller blade offers a superior view of the laryngeal inlet because it lifts the epiglottis. However, others use the Miller blade to expose the larynx without lifting the epiglottis, supposedly to avoid traumatizing it. Despite the long-standing use of these blades, more than 50 years, no systematic study has ever compared the laryngoscopy views of the Miller and Macintosh blades in infants.
Condition or disease | Intervention/treatment | Phase |
---|---|---|
Percent of Glottic Opening | Device: Laryngoscope blade | Not Applicable |
- After Institutional Review Board approval, the patients meeting inclusion criteria will be selected from the Operating room elective surgical list.
- They will be randomized to one of the two groups: a #1 Miller or Macintosh blade.
- After obtaining informed consent from the parent or the legal guardian, monitors (electrocardiogram, non-invasive blood pressure monitor and pulse oximeter) that are routine induction of anesthesia will be applied and anesthesia will be induced using an inhalation technique with sevoflurane, nitrous oxide and oxygen. An intravenous cannula will then be placed. The child will then receive a standard intubating dose of a muscle relaxant (rocuronium 0.5-1 mg/kg). The lungs will be mask ventilated using 100% oxygen in Sevoflurane for 3 minutes to allow appropriate time for the muscle relaxant to be fully effective. At that time, the randomized code for that child will be opened and laryngoscopy will be performed with either a Miller or MacIntosh blade as indicated by the code.
- The best possible glottic view will be obtained by ensuring the following steps. The child's head will be positioned in the Magill position, muscle relaxant will be administered, firm forward traction will be applied to the laryngoscope handle, and if needed, external laryngeal manipulation will be applied.
- During the same laryngoscopy, the best glottic visualization will be obtained with the blade lifting the epiglottis and not lifting the epiglottis, in random order (by flipping a coin). This difference is a matter of moving the position of the blade back without removing the blade from the larynx.
- The two views will be recorded by a second doctor using a SONY camera at the mouth adjacent to the laryngoscope handle.
- Photos of the glottic opening will be graded using the POGO scale (Ref1) by a third (blinded) anesthesiologist.
- All of the intubations and image acquisition will be performed by Drs. Yuvesh Passi, Jerrold Lerman or Chris Heard.
- The images obtained will not have patient identifiers included. They will be stored in a secure file once the study is completed that will be accessed only by investigators involved in the study.
- No patient identifiers will be included on any documentation apart from the source documents.
- The research data will be stored in a locked office of Dr. Lerman (Room 251) in Department of Anesthesia, Women and Children's Hospital of Buffalo during and after the study for security to protect subject privacy and confidentiality.
- There will be no payments or compensation to the study subjects
The primary hypothesis of this study is to compare the view of the larynx with Miller blade while lifting the epiglottis to the Macintosh blade lifting the tongue, in infants and children <2 years of age. However, views will be obtained with the Miller and Macintosh blades both lifting and not lifting the epiglottis and comparisons between pairs of measurements will be performed. In order for to detect superiority of one technique over the other, we will need a difference in the POGO scores of 25 points with a standard deviation of 25 points, yielding a sample size of 15 children in each group. To account for photographic difficulties, unreadable photos as well as dropouts, we will enroll 25 children in each group. Therefore a total of 50 children will be enrolled.
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Study Type : | Interventional (Clinical Trial) |
Actual Enrollment : | 50 participants |
Allocation: | Randomized |
Intervention Model: | Parallel Assignment |
Masking: | Single (Outcomes Assessor) |
Primary Purpose: | Treatment |
Official Title: | Comparing the Laryngoscopy View Using Miller and Macintosh Laryngoscopy Blades in Infants Under Two Years of Age |
Study Start Date : | October 2012 |
Actual Primary Completion Date : | July 2013 |
Actual Study Completion Date : | July 2013 |
Correspondence
Following the paucity of data highlighted by Oakes et al. 1 regarding videolaryngoscopy in paediatrics, we would like to report our experience of using a new size‐1 blade for the McGrath® MAC videolaryngoscope (Aircraft Medical, Edinburgh, UK) to facilitate intubation in neonates.
The potential merits of videolaryngoscopy over conventional direct laryngoscopy in children have been discussed in the meta‐analysis by Sin and colleagues last year 2. In addition, two recent studies highlighted the challenges of neonatal intubation comparing direct laryngoscopy with the size‐1 Miller and Macintosh blades in children under two years of age 3, 4 and were followed by much comment and controversy 5, 6. The McGrath MAC 1 blade has only recently been developed and we were given a selection of these disposable blades to trial in our unit. This is the first reported use of this blade in clinical practice.
We used this new blade in a 36‐week‐old neonate weighing 2.4 kg. We passed the videolaryngoscope blade to the right of the tongue and inserted the tip into the vallecula to depress the hypoepiglottic ligament and lift the epiglottis. We scored the direct laryngoscopy view before scoring the indirect video image. In our limited experience, the videolaryngoscopy view was improved over that obtained under direct laryngoscopy (Fig. 3).
We have since used this blade for intubation in the following infants and neonates:
- 0.8‐kg, 25‐week‐old neonate
- 2.3‐kg, 36‐week‐old neonate
- 2.4‐kg, 38‐week‐old neonate
- 4.0‐kg, 2‐week‐old (42 weeks corrected) neonate
- 5.4‐kg, 6‐week‐old (48 weeks corrected) infant
As with any anterior and cephalad larynx, we felt that facilitating intubation in this age group was best achieved with a pre‐loaded stylet inside the tracheal tube, which is common practice in our unit.
We felt the greatest advantage of this new small videolaryngoscope blade was in the magnification of the view of the laryngeal inlet. There is a further advantage in the demonstration and training of neonatal intubation. The device emulates the traditional Macintosh laryngoscope in both design and the application of an appropriately sized blade to a standard handle.
There remains a paucity of data regarding the McGrath MAC 1 videolaryngoscope in neonates and infants and we look forward to compiling a case series of our further experience with this new equipment.
Acknowledgement
We are grateful to Aircraft Medical for the use of the McGrath MAC 1 videolaryngoscope blade. Published with the written consent of the parents of the patients described.
Competing Interests
AB has assisted Aircraft Medical in the development of the McGrath videolaryngoscope on a consultative basis. AB did not receive a fee for this advice and has/has never had a financial interest in this or any anaesthetic equipment company.
- 1, , . Difficulties using the C‐MAC paediatric videolaryngoscope. Anaesthesia2013; 68: 653– 4. Wiley Online LibraryPubMedWeb of Science®Google Scholar
- 2, , , . Pediatric video laryngoscope versus direct laryngoscope: a meta‐analysis of randomized controlled trials. Pediatric Anesthesia2014; 24: 1056– 1065. Wiley Online LibraryPubMedWeb of Science®Google Scholar
- 3, , , et al. 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. British Journal of Anaesthesia2014; 113( 5): 869– 74.
- 4, . Does the Miller blade truly provide a better laryngoscopic view and intubating conditions than the Macintosh blade in small children?Pediatric Anesthesia2014; 24: 825– 829. Wiley Online LibraryCASPubMedWeb of Science®Google Scholar
- 5, . Comment on Varghese and Kundu, does the Miller blade truly provide a better laryngoscopic view and intubating conditions than the Macintosh blade in small children?Pediatric Anesthesia2014; 24: 1188– 1198. Wiley Online LibraryPubMedWeb of Science®Google Scholar
- 6, . Reply to comments on our paper ‘Does the Miller blade truly provide a better laryngoscopic view and intubating conditions than the Macintosh blade in small children?’Pediatric Anesthesia2014; 24: 1305– 1314.