Channelled versus nonchannelled Macintosh videolaryngoscope blades in patients with a cervical collar: a randomized controlled noninferiority trial.

PURPOSE: Channelled blades have the advantage of avoiding stylet use and potential airway injury during videolaryngoscopic intubation. Nevertheless, the effectiveness of channelled Macintosh-type blades has not yet been fully established. We sought to assess the utility of channelled Macintosh-type blades for videolaryngoscopic intubation under cervical spine immobilization. METHODS: We conducted a randomized controlled noninferiority trial in neurosurgical patients with a difficult airway simulated by a cervical collar. Videolaryngoscopic intubation with a reinforced tracheal tube was performed using a channelled Macintosh-type blade without a stylet (channelled group, n = 130) or a nonchannelled Macintosh-type blade with a stylet (nonchannelled group, n = 131). The primary outcome was intubation success rate. Secondary outcomes included time to intubation and incidence or severity of intubation-related complications (subglottic, lingual, and dental injuries; bleeding; sore throat; and hoarseness). RESULTS: The initial intubation success rate was 98% and 99% in the channelled and nonchannelled groups, respectively, showing the noninferiority of the channelled group (difference in proportions -0.8%; 95% confidence interval [CI], -4.8% to 2.9%; predefined noninferiority margin, -5%; P = 0.62). Fewer participants in the channelled group had subglottic injuries than in the nonchannelled group (32% [32/100] vs 57% [54/95]; difference in proportions, -25%; 95% CI, -39% to -11%; P < 0.001). There were no significant differences between the two groups in the overall intubation success rate, time to intubation, and incidence or severity of other intubation-related complications. CONCLUSIONS: For videolaryngoscopic intubation in patients with a cervical collar, channelled Macintosh-type blades are an alternative to nonchannelled Macintosh-type blades, with a noninferior initial intubation success rate and a lower incidence of subglottic injury. STUDY REGISTRATION: CRIS.nih.go.kr ( KCT0005186 ); first submitted 29 June 2020.

RéSUMé: OBJECTIF: Les lames avec canal ont l'avantage de ne pas nécessiter l'utilisation d'un stylet et d'ainsi éviter les lésions potentielles des voies aériennes lors de l'intubation vidéolaryngoscopique. Néanmoins, l'efficacité des lames avec canal de type Macintosh n'a pas encore été pleinement établie. Nous avons cherché à évaluer l'utilité des lames avec canal de type Macintosh pour l'intubation vidéolaryngoscopique lorsque le rachis cervical était immobilisé. MéTHODE: Nous avons mené une étude randomisée contrôlée de non-infériorité chez des patient·es de neurochirurgie présentant des voies aériennes difficiles simulées par le port d'un collier cervical. L'intubation vidéolaryngoscopique avec une sonde trachéale renforcée a été réalisée à l'aide d'une lame Macintosh avec canal sans stylet (groupe avec canal, n = 130) ou d'une lame Macintosh sans canal avec stylet (groupe sans canal, n = 131). Le critère d'évaluation principal était le taux de réussite de l'intubation. Les critères d'évaluation secondaires comprenaient le temps d'intubation et l'incidence ou la gravité des complications liées à l'intubation (lésions sous-glottiques, linguales et dentaires, saignements, maux de gorge et enrouement). RéSULTATS: Le taux de réussite initial de l'intubation était de 98 % et 99 % dans les groupes avec et sans canal, respectivement, montrant la non-infériorité du groupe lame avec canal (différence de proportions −0,8 %; intervalle de confiance [IC] à 95 %, −4,8 % à 2,9 %; marge de non-infériorité prédéfinie, −5 %; P = 0,62). Les lésions sous-glottiques ont été moins nombreuses dans le groupe avec canal que dans le groupe sans canal (32 % [32/100] vs 57 % [54/95]; différence de proportions, −25 %; IC 95 %, −39 % à −11 %; P < 0,001). Il n'y avait pas de différences significatives entre les deux groupes en matière de taux global de réussite de l'intubation, de temps d'intubation et d'incidence ou de gravité des autres complications liées à l'intubation. CONCLUSION: Pour l'intubation vidéolaryngoscopique des patient·es portant un collier cervical, les lames avec canal de type Macintosh constituent une alternative aux lames sans canal de type Macintosh, avec un taux de réussite d'intubation initial non inférieur et une incidence plus faible de lésions sous-glottiques. ENREGISTREMENT DE L'éTUDE: CRIS.nih.go.kr ( KCT0005186 ); première soumission le 29 juin 2020.

A Randomized Crossover Study Comparing Cervical Spine Motion During Intubation Between Two Lightwand Intubation Techniques in Patients With Simulated Cervical Immobilization: Laryngoscope-Assisted Versus Conventional Lightwand Intubation.

BACKGROUND: In patients with cervical immobilization, jaw thrust can cause cervical spine movement. Concurrent use of a laryngoscope may facilitate lightwand intubation, allowing midline placement and free movement of the lightwand in the oral cavity without jaw thrust. We compared the effects of laryngoscope-assisted lightwand intubation (LALI) versus conventional lightwand intubation (CLI) on cervical spine motion during intubation in patients with simulated cervical immobilization. METHODS: In this randomized crossover study, the cervical spine angle was measured before and during intubation at the occiput-C1, C1-C2, and C2-C5 segments in 20 patients with simulated cervical immobilization who underwent intubation using both the LALI and CLI techniques. Cervical spine motion was defined as the change from baseline in angle measured at each cervical segment during intubation. RESULTS: Cervical spine motion at the occiput-C1 segment was 5.6° (4.3) and 9.3° (4.5) when we used the LALI and CLI techniques, respectively (mean difference [98.33% CI]; -3.8° [-7.2 to -0.3]; P = .007). At other cervical segments, it was not significantly different between the 2 techniques (-0.1° [-2.6 to 2.5]; P = .911 in the C1-C2 segment and -0.2° [-2.8 to 2.5]; P = .795 in the C2-C5 segment). CONCLUSIONS: The LALI technique produces less upper cervical spine motion during intubation than the CLI technique in patients with simulated cervical immobilization.

A randomized controlled trial of the effect of preoperative dexmedetomidine on the half maximal effective concentration of propofol for successful i-gel insertion without muscle relaxants.

BACKGROUND: Dexmedetomidine is a useful anesthetic adjuvant for general anesthesia. We determined whether preoperative dexmedetomidine administration could reduce the half maximal effective concentration (EC50) of propofol for successful i-gel insertion without muscle relaxants. METHODS: Thirty-seven patients were randomly allocated to one of two groups. In the dexmedetomidine group (n = 19), dexmedetomidine (1 µg/kg) was loaded for 10 min preoperatively. In the control group (n = 20), the same volume of 0.9% normal saline was administered in the same manner. The EC50 of propofol for successful i-gel insertion was determined using Dixon's up-and-down method. The EC50 of propofol was calculated as the midpoint concentration after at least six crossover points had been obtained. For successful i-gel insertion, all of the following four factors were required­(1) no major movement of the body within 1 min of insertion, (2) no significant resistance to mouth opening, (3) cough ≤2, and (4) visible square wave capnogram without air leakage at a peak airway pressure of <10 cmH2O. Mean blood pressure (MBP) and heart rate (HR) were monitored during the peri-insertion period of i-gel. RESULTS: The EC50 of propofol for successful i-gel insertion was 3.18 µg/mL in the dexmedetomidine group and 6.75 µg/mL in the control group (p < 0.001). The incidence of hypotension (MBP <80% of the baseline) during the peri-insertion period of i-gel was higher in the control group (p = 0.001), whereas the incidence of bradycardia (HR <80% of the baseline) was higher in the dexmedetomidine group (p = 0.001). CONCLUSIONS: Preoperative dexmedetomidine reduced the EC50 of propofol for successful i-gel insertion without muscle relaxants.

Optimal headrest height for the best laryngoscopic view: by anatomical measurements.

BACKGROUND: We hypothesized that the oro-pharyngolaryngeal axes, occipito-atlanto-axial extension (OAA) angle and intubation distance would be influenced by the height of headrests. METHODS: Twenty patients were enrolled. The Macintosh 3 blade was used for direct laryngoscopy without a headrest or with the headrest of 6 or 12 cm high in randomized order, whereas a lateral radiograph of the neck was taken when the best laryngoscopic view was obtained. The following measurements were made: (1) the axis of the mouth (MA), the pharyngeal axis (PA), the laryngeal axis (LA), and the line of vision (LV). The various angles between these axes were defined: α angle between MA and PA, ß angle between PA and LA, and δ angle between LV and LA. (2) Intubation distance, (3) mentovertebral distance, and (4) OAA angle. RESULTS: Compared with 12-cm and no headrest, the δ angle decreased significantly with 6-cm headrest (19.4°/29.2°/29.2° in 6-cm/12-cm/no headrest, respectively; P < .001), and the intubation distance increased significantly (46.2/37.3/38.7 mm in 6-cm/12-cm/no headrest, respectively; P < .001). Mentovertebral distance was smallest (107.0/106.7/98.5 mm; P < .05) at 12-cm headrest. Occipito-atlanto-axial extension angle was largest significantly (40.7°/35.2°/34.5°; P < .05) at 6-cm headrest. CONCLUSION: We conclude that compared with no or 12-cm headrest, 6-cm headrest could facilitate more alignment of these axes, increase the OAA angle, and enlarge the intubation distance.

The 90° rotation technique improves the ease of insertion of the ProSeal™ laryngeal mask airway in children.

BACKGROUND: A previous study using a 180° rotation to insert the ProSeal™ laryngeal mask airway (LMA ProSeal) in children did not show improvement over the standard technique. We used a 90° rotation technique to insert the LMA ProSeal in pediatric patients and compared ease of insertion and pharyngeal trauma with the standard technique. METHODS: This prospective randomized controlled study included 126 patients aged three to nine years. Anesthesia was induced with thiopental and rocuronium, and the LMA ProSeal used in the study ranged in size from 2 to 3 depending on the patient's body weight. In the control group (n = 63), the LMA ProSeal was inserted using the index finger. In the rotation group (n = 63), the entire cuff of the LMA ProSeal was placed in the patient's mouth without finger insertion and rotated 90° counter clockwise around the tongue. The LMA ProSeal was then advanced and rotated back until resistance was felt. The primary outcome was the insertion success rate at first attempt. RESULTS: The success rate of insertion at first attempt was higher with the rotation technique than with the standard technique (97% vs 70%, respectively; P < 0.001) and the insertion time was shorter (16 ± 6 sec vs 30 ± 24 sec, respectively; P < 0.001). Mean blood pressure after LMA ProSeal insertion increased significantly in the control group (62 ± 12 to 69 ± 17 mmHg; P = 0.01), but not in the rotation group. The incidence of blood staining was lower in the rotation group than in the control group (10% vs 25%, respectively; P = 0.03), but the incidence of sore throat was not significantly different (24% vs 22%, respectively; P = 0.9). CONCLUSIONS: The 90° rotation technique improves ease of insertion of the LMA ProSeal in children, and it decreases the risk of pharyngeal trauma. (ClinicalTrials.gov number, NCT01076725).

Insertion of the ProSeal laryngeal mask airway is more successful with the 90 degrees rotation technique.

PURPOSE: The 90 degrees rotation technique for inserting the ProSeal laryngeal mask airway (PLMA) in anesthetized paralyzed patients was compared with the index finger insertion technique. METHODS: One hundred twenty Asian adult patients were randomly allocated to either a standard technique group or a rotation technique group. A PLMA size 4 was used for women and size 5 was used for men. In the standard technique group (n = 60), the PLMA was inserted using the index finger. In the rotation technique group (n = 60), the entire cuff of the PLMA was placed in the patient's mouth in a midline approach without finger insertion, rotated 90 degrees counter clockwise around the patient's tongue, advanced and then rotated back until resistance was felt. The primary outcome was success at first insertion. Secondary outcome measures were insertion time and complications. RESULTS: The success rate at first insertion was greater for the rotation technique group than for the standard technique group (100% vs 83%, respectively; P = 0.003), and less time was required (11 +/- 3 sec vs 19 +/- 16 sec, respectively; P = 0.03). The incidence of postoperative sore throat was lower for the rotation technique group than for the standard technique group (12% vs 33%, respectively; P = 0.009), and blood staining on the PLMA was less (8% vs 40%, respectively; P < 0.001). CONCLUSION: The 90 degrees rotation technique for inserting the PLMA is more successful than the standard index finger insertion technique. It is associated with fewer side effects, such as blood on the PLMA and sore throat, which suggests it causes less pharyngeal trauma.

Comparison of two insertion techniques of ProSeal laryngeal mask airway: standard versus 90-degree rotation.

BACKGROUND: This study compared two insertion techniques of ProSeal laryngeal mask airway. METHODS: A total of 160 female patients (American Society of Anesthesiologists physical status I or II; age 18-80 yrs) undergoing gynecologic surgery were randomly allocated to the standard or rotational technique groups. In the standard technique group (n = 80), ProSeal laryngeal mask airway insertion was performed by a single experienced user using digital manipulation. In the rotational technique group (n = 80), the ProSeal laryngeal mask airway was rotated counter clockwise through 90 degrees in the mouth and advanced until the resistance of the hypopharynx was felt, and then straightened out in the hypopharynx (n = 80). The ease of insertion was assessed by the success rate at the first attempt. Heart rate and mean blood pressure were recorded 1 min before and 1 min after insertion. Postoperative complications were noted. RESULTS: The success rate of insertion at the first attempt was higher for the rotational technique (100% vs. 85%, P < 0.001). The overall success rate, i.e., successful insertion within three attempts, was 94% for the standard technique versus 100% for the rotational technique. There was no significant change in heart rate, but mean blood pressure increased significantly with the standard technique (P = 0.001). The incidence of blood staining (9% vs. 36%, P < 0.001) and sore throat (8% vs. 25%, P = 0.005) was lower with the rotational technique. CONCLUSION: The rotational technique is more successful than the standard technique and is associated with less pharyngeal mucosal trauma, as evidenced by a lower incidence of sore throat and mucosal bleeding.

Radiographic Predictors of Difficult Laryngoscopy in Acromegaly Patients.

BACKGROUND: Patients with acromegaly have a high risk of difficult laryngoscopy. However, clinical predictors, such as upper lip bite test or modified Mallampati class, show limited predictive performance for difficult laryngoscopy in such patients. In this retrospective study, we evaluated radiographic indices obtained from skull lateral x-ray and ostiomeatal unit computed tomography images to predict difficult laryngoscopy in acromegaly patients. MATERIALS AND METHODS: Data on demographics, preoperative serum levels of pituitary hormones, and radiographic indices were collected from 90 acromegaly patients that underwent transsphenoidal removal for pituitary tumor from January 2010 to December 2016. Difficult laryngoscopy was defined as Cormack-Lehane grade ≥III. RESULTS: Difficult laryngoscopy occurred in 21 (23%) patients. In univariate analysis, age and radiographic indices indicating tongue size, such as tongue area (TA) on ostiomeatal unit computed tomography, linear distance from the alveolar line of the mandible to the hyoid bone, and linear distance from the interior border of the mandible to the hyoid bone on skull lateral x-ray, were associated with difficult laryngoscopy. In multivariate analysis, age (odds ratio [95% confidence interval], 1.084 [1.037-1.190]; P=0.002) and TA (1.002 [1.000-1.003], P=0.014) were independent risk factors for difficult laryngoscopy. The area under the curve of the combined model of age and TA was 0.80. CONCLUSIONS: Old age and radiographic predictors indicating large tongue size (large TA, long alveolar line of the mandible to the hyoid bone and mandible to the hyoid bone) were associated with an increased rate of difficult laryngoscopy in acromegaly patients. Preoperative radiographic measurements of tongue size can be helpful for safe airway management in such patients.