Andrew D. Milne

Airway management using the pediatric GlideScope in a child with Goldenhar syndrome and atypical plasma cholinesterase.

We report a case of difficult intubation in a child with Goldenhar syndrome and atypical plasma cholinesterase. Intubation attempts by direct laryngoscopy and the TrachlightTM were unsuccessful. The airway was ultimately secured using the pediatric GlideScope® in conjunction with external laryngeal manipulation.

What is an unacceptable light level for direct laryngoscopy

To the Editor,Optimal lighting level may be crucial to successfultracheal intubation. However, the minimum light levelrequired for direct laryngoscopic intubation has not beenclearly defined using a standardized method of testing. Twoprior studies have reported that the minimum luminance orilluminance level required for intubation is approximately100 candela m

The effect of sterilisation on the light intensity of the reusable Trachlight

We examined the light intensity delivered by the Trachlight™ reusable lightwand and the effect of repeated sterilisation on this light intensity. Using a light meter and test chamber, the light intensity of 12 new Trachlights and 31 Trachlights available in operating theatres was measured. In addition, five new devices underwent 30 repeated sterilisations with light intensity measurement after each cleaning. There was no difference between the light intensity of new Trachlights (median (IQR [range]) 2282 (2202–2780 [1970–4400])) lux and the devices currently in service (2295 (2018–2796 [1649–3280]) lux (p = 0.27)). The median (range) number of uses for devices currently in service was only 3 (0–9). There was, however, significant light intensity loss after 10, 20 and 30 cleanings (p = 0.001). After 10 cleanings, the mean light intensity was 75% of initial output, and after 30 cycles, light intensity was 59% of initial output.

Effects of laryngoscope handle light source on the light intensity from disposable laryngoscope blades.

A bench‐top study was performed to assess the effects of different laryngoscope handles on the light intensity delivered from disposable metal or plastic laryngoscope blades. The light intensity from both the handle light sources themselves and the combined handle and laryngoscope blade sets was measured using a custom‐designed testing system and light meter. Five samples of each disposable blade type were tested and compared with a standard re‐usable stainless steel blade using three different handle/light sources (Vital Signs LED, Heine 2.5 V Xenon and 3.5 V Xenon). The light intensity delivered by the disposable blades ranged from 790 to 3846 lux for the different handle types. Overall, the 3.5 V Heine handle delivered the highest light output (p < 0.007) in comparison with the other handles. For the disposable blades, the overall light output was significantly higher from the plastic than the metal blades (p < 0.001).

Three-Dimensional Morphologic Nasal Surface Characteristics That Predict the Extremes of Esthetics in Patients With Repaired Cleft Lip and Palate

Objective The purposes of this study were (1) to develop imaging methods and objective numeric parameters to describe nose morphology, and (2) to correlate those parameters with nasal esthetics for patients with clefts. Methods A total of 28 patients with repaired complete unilateral cleft lip and palate (CUCLP) and 20 age- and gender-matched individuals without clefts were identified. A panel of orthodontists rated and ranked nasal esthetics from nose casts for the cleft group. Best and worst esthetic cleft groups were established from the cast assessments. Three-dimensional surface coordinates of the casts were digitally mapped with an electromagnetic tracking device. Digitized nasal images were oriented, voxelated, sliced, and mathematically curve-fitted. Maximum difference, percent area difference, and maximum and minimum derivative differences between cleft and noncleft and between right and left nose sides were calculated. Differences in parameters between groups were assessed with the use of analysis of variance (ANOVA) and t tests, and correlations with esthetics were assessed with the Spearman rank correlation test. Results Differences were seen between cleft and noncleft and best and worst esthetic groups for all four parameters (p < .05). The best esthetic cleft group had (1) lower percent area difference (p < .0001), (2) lower maximum difference (p < .001), and (3) smaller differences in slope of the nose in the coronal plane (p < .0001) than the worst esthetic cleft group. Conclusions Maximum difference and maximum derivative difference and, to a lesser degree, percent area difference can be used to identify differences between cleft and noncleft nasal morphology and to assess levels of nasal esthetics for patients with CUCLP.

Prevalence of difficult airway in obstructive sleep apnea patients

INTRODUCTION: Obstructive sleep apnea syndrome (OSA) is a common condition (2-4% of adults) that has been associated with an increased risk of difficult intubation. Two smaller studies (n=15-36) and one larger study (n=90) have estimated the rate of difficult intubation to be 16.753% in OSA patients[1-3]. The purpose of this retrospective study was to determine the prevalence of difficult intubation in a large cohort of OSA patients. METHODS: After obtaining IRB approval, OSA patients undergoing surgical procedures were identified by combining a database of polysomnography patients with our surgical booking database (Jan 2003-Dec 2005). Sleep lab charts were reviewed for height, weight, apneahypopnea indices, lowest nocturnal oxygen saturation and self-reported scores of sleep disturbance. Anesthetic records were reviewed for type of surgery and anesthetic method. The lowest oxygen saturation at induction (LSAT) and pertinent airway data were also extracted. Difficult intubation was defined as Cormack-Lehane Grade 3 or 4 direct laryngoscopy, fibreoptic intubation (FOB) or more than 2 intubation attempts by any method[3]. RESULTS: A total of 215 OSA patients (147/68 Male/Female) underwent 297 anesthetic procedures over a 3-year period. Lefort-BSSO surgeries were the most common procedure (11%). The anesthetic and airway techniques employed were: direct laryngoscopy 52.9% (n=157), awake/asleep FOB 6.1% (n=18), Lightwand 6.1% (n=18), Bullard/Glidescope 1.3% (n=4), LMA 11.8% (n=35), spinal/regional 5.1% (n=15), sedation/local 12.5% (n=37) and other 1.0% (n=3). An endotracheal tube was already in-situ for 10 procedures. Table 1 summarizes the airway grades, BMI, and LSAT at induction (mean ± SD). Three patients with Grade 1-2 laryngeal view required 3 laryngoscopic intubation attempts. Based on these results the overall prevalence of difficult intubation was calculated to be 38/197 (19.3%).

Unilateral hypoplasia of the trigeminal ganglion

CASE REPORT We report a case of unilateral anaesthesia of the V1 (ophthalmic) division of the trigeminal cranial nerve presenting with persistent corneal erosions and ulceration secondary to trigeminal ganglion hypoplasia. The patient had a lifelong history of unexplained left-sided ophthalmic symptoms for which numerous diagnoses were provided. Cranial nerve testing demonstrated partial trigeminal dysfunction on the left side. Further investigation eliminated viral etiologies, and subsequent magnetic resonance imaging determined that the patient had a hypo-plastic left trigeminal ganglion. COMMENTS We present the case to alert clinicians to the possibility of this rare condition.

Shelf life of rechargeable laryngoscope batteries without recharging

To the Editor, Proper laryngeal illumination is a crucial component of providing optimal conditions for tracheal intubation under direct laryngoscopy. Intubating equipment is often used and checked on a daily basis in the operating room; however, laryngoscopes often lie inactive for prolonged periods in emergency airway kits for the general wards, the emergency room, critical care units, or out-of-hospital use. Limited data are published on the life span of laryngoscope batteries or the safe storage period for emergency airway kits. We undertook to evaluate the useful ‘‘shelf life’’ of a commonly used laryngoscope device without battery recharging between uses. Institutional research ethics board approval was unnecessary for this simple bench test of a single laryngoscope to evaluate battery life between full charges. A new Heine 3.5 volt Xenon laryngoscope handle with a new nickel metal hydride (NiMH) battery and a new Heine Macintosh #3 Classic reusable fibreoptic stainless steel blade (Herrsching, Germany) was evaluated. The rechargeable battery was fully charged at the start of this study. The light intensity delivered from the handle and blade unit was tested daily using a previously described testing chamber and light meter. Light output was recorded after 30 sec of usage on each day (Figure). Testing was stopped on day 181 after the light output had dropped to 2,000 lux. This bench-top test shows that new NiMH battery sets can hold their charge for prolonged periods of time without requiring recharging. Testing was stopped arbitrarily once the light output had reached 2,000 lux as this is the threshold level that our institution had deemed as a minimum safe light requirement prior to introduction of the new International Organization for Standardization (ISO) guidelines of 500 lux. Our observations are limited by the fact that we tested a single new device with only one type of rechargeable battery (i.e., NiMH vs lithium or nickel cadmium batteries), and we did not examine battery ‘‘memory’’ effects. Despite these limitations, these observations over 181 days do help to characterize performance of these new laryngoscopes over prolonged storage periods under minimal usage conditions. These data should be useful to other institutions for equipment life cycle management and planning and for establishing quality control testing protocols for emergency airway equipment.

Laryngoscope brightness determined by visual inspection and during mannequin laryngoscopy

To the Editor, Adequate light intensity is crucial for visualization during laryngoscopy. This can be problematic as light intensity of laryngoscope blades deteriorates with repeated use and cleaning. Typically, laryngoscope function is checked by simple visual assessment of blade light brightness prior to induction. While the Canadian Guidelines to the Practice of Anesthesia stipulate that laryngoscopes must be checked prior to use, they do not specify a method. The aim of this present study was to compare the adequacy of laryngoscope blade light brightness, as perceived by simple visual inspection, with the adequacy of illumination during direct laryngoscopy performed on a mannequin. After institutional research ethics board approval (CDHA-RS2014-074, July 2013), a convenience sample of 35 anesthesia staff and residents (n = 25 and 10, respectively) provided written informed consent to participate. A laryngoscope brightness testing chamber was employed to identify ten used laryngoscope blades with light intensities ranging from approximately 140– 2,200 lux (Table). This range encompasses previously proposed minimum light intensity requirements for laryngoscopy. Ten baseline illumination measurements were obtained for each blade using a single new 3.5 volt rechargeable handle fitted with a xenon bulb (Heine, Herrsching, Germany) prior to assessment by study participants. Participants were blinded to the measured brightness intensity of each blade. Each participant was given the ten laryngoscope blades in random order (computer generated random number sequence) and asked to visually assess the blades for their brightness as they would do during their routine preinduction check. The rating of the blade brightness was recorded as either ‘‘acceptable’’ or ‘‘unacceptable’’. After completing visual inspection of all ten blades, the participant was then asked to assess the light intensity of the blades (acceptable/unacceptable) during laryngoscopy on a mannequin (Laerdal, Stavanger, Norway). As before, the order of blade testing was randomized. The mean ambient room lighting for all testing sessions was 406 ± 84 lux (1 standard deviation). The laryngoscope handle was recharged for ten minutes after each participant’s assessment and the brightness of each blade was rechecked after each test to ensure no inadvertent changes in light intensity. The proportion of participants rating each blade as ‘‘acceptable’’ was calculated along with the 95% confidence interval (CI). Blade acceptance was compared using the Fisher exact test and Bonferroni correction. Acceptability of blade brightness during visual inspection vs mannequin laryngoscopy was analyzed for each individual blade. The proportion of participants accepting a given blade compared with the brightest blade (blade # 10) was also analyzed for both visual inspection and mannequin laryngoscopy. Given our sample size, we Presented in part at the Canadian Anesthesia Society Annual Meeting, Ottawa, Ontario, Canada, June 2015. (Amended data.)

In reply: No reduction in fibreoptic intubation rates with universal video laryngoscopy

To the Editor, We thank Drs. Thomas, Kelly, and Cook for their interest in our publication and for sharing their experience. As they point out, in spite of a significant increase in the rate of using video laryngoscopy (VL) at our institution over the studied time period of 2002-2013, we use VL to facilitate only a small percentage of tracheal intubations (810% from 2012 to 2013). Granted, that figure rises slightly to 10-12% when other alternatives to direct laryngoscopy, e.g., lighted stylet, are also considered. We continue to use VL chiefly for anticipated or known situations of difficult direct laryngoscopy or for teaching purposes. It was interesting to learn that Dr. Thomas et al. reported an overall incidence of awake tracheal intubation (about 1%) which is similar to ours. We look forward to a report from Dr. Thomas et al. some years hence that will clarify whether their universal use of VL has had an impact on the incidence of awake tracheal intubation over a longer time period, or, as with our results, the need for awake tracheal intubation appears to remain relatively fixed.