A multicentre randomised controlled trial of the McGrath™ Mac videolaryngoscope versus conventional laryngoscopy

Before completion of this study, there was insufficient evidence demonstrating the superiority of videolaryngoscopy compared with direct laryngoscopy for elective tracheal intubation. We hypothesised that using videolaryngoscopy for routine tracheal intubation would result in higher first-pass tracheal intubation success compared with direct laryngoscopy. In this multicentre randomised trial, 2092 adult patients without predicted difficult airway requiring tracheal intubation for elective surgery were allocated randomly to either videolaryngoscopy with a Macintosh blade (McGrath™) or direct laryngoscopy. First-pass tracheal intubation success was higher with the McGrath (987/1053, 94%), compared with direct laryngoscopy (848/1039, 82%); absolute risk reduction (95%CI) was 12.1% (10.9–13.6%). This resulted in a relative risk (95%CI) of unsuccessful tracheal intubation at first attempt of 0.34 (0.26–0.45; p < 0.001) for McGrath compared with direct laryngoscopy. Cormack and Lehane grade ≥ 3 was observed more frequently with direct laryngoscopy (84/1039, 8%) compared with McGrath (8/1053, 0.7%; p < 0.001) No significant difference in tracheal intubation-associated adverse events was observed between groups. This study demonstrates that using McGrath videolaryngoscopy compared with direct laryngoscopy improves first-pass tracheal intubation success in patients having elective surgery. Practitioners may consider using this device as first choice for tracheal intubation.     

Peak intratracheal pressure during controlled ventilation in infants and children

The mathematical relationship between peak ventilator breathing system pressure displayed on the digital meter of the Siemens SV900C ventilator, and peak intratracheal pressure measured at the distal end of the tracheal tube, was defined and incorporated into a computer program. The mean difference between peak airway pressure calculated by the computer and directly measured peak intratracheal pressure was 0.02 kPa (SD 0.10) in 18 infants and children. The mean difference between ventilator breathing system pressure and intratracheal pressure in the same group was 0.82 kPa (SD 0.91). Bench tests established that the decrease in peak pressure displayed by the ventilator (from 1.36 to 0.38 kPa) while inspiratory time was increased from 20 to 80% of the respiratory period, concealed an increase (from 0.2 to 0.38 kPa) in intratracheal pressure which occurs during this process; and that the large increase in pressure displayed by the ventilator (from 0.3 to 6 kPa) while respiratory frequency was increased from 20 to 120 breaths/minute, concealed a small increase in peak intratracheal pressure (0.2-0.3 kPa) which occurs during this process. These changes were accurately predicted by the computer program. The increase in intratracheal pressure associated with prolonged inspiratory times explains the high incidence of barotrauma which has recently been associated with this procedure in infants.     

Measurement of airway pressure during high-flow nasal therapy in apnoeic oxygenation: a randomised controlled crossover trial*

It is recognised that high-flow nasal therapy can prevent desaturation during airway management. Studies in spontaneously breathing patients show an almost linear relationship between flow rate and positive airway pressure in the nasopharynx. Positive airway pressure has been suggested as one of the possible mechanisms explaining how high-flow nasal therapy works. However, data on pressures generated by high-flow nasal therapy in apnoeic adults under general anaesthesia are absent. This randomised controlled crossover trial investigated airway pressures generated by different flow rates during high-flow nasal therapy in anaesthetised and paralysed apnoeic patients, comparing pressures with closed and open mouths. Following induction of anaesthesia and neuromuscular blockade, a continuous jaw thrust was used to enable airway patency. Airway pressure was measured in the right main bronchus, the middle of the trachea and the pharynx, using a fibreoptically-placed catheter connected to a pressure transducer. Each measurement was randomised with respect to closed or open mouth and different flow rates. Twenty patients undergoing elective surgery were included (mean (SD) age 38 (18) years, BMI 25.0 (3.3) kg.m^-2, nine women, ASA physical status 1 (35%), 2 (55%), 3 (10%). While closed mouths and increasing flow rates demonstrated non-linear increases in pressure, the pressure increase was negligible with an open mouth. Airway pressures remained below 10 cmH₂O even with closed mouths and flow rates up to 80 l.min⁻¹; they were not influenced by catheter position. This study shows an increase in airway pressures with closed mouths that depends on flow rate. The generated pressure is negligible with an open mouth. These data question positive airway pressure as an important mechanism for maintenance of oxygenation during apnoea.     

Comparison of the CobraPLA (Cobra Perilaryngeal Airway) and the Laryngeal Mask Airway Unique in children under pressure controlled ventilation

Background: The Laryngeal Mask Airway‐Unique (LMAU) and CobraPLA^TM (Cobra Perilaryngeal Airway) are supraglottic airway devices. There are no published studies comparing these devices in children breathing with pressure controlled ventilation (PCV). Methods: Eighty pediatric patients, scheduled for elective general surgery of short duration, were randomly assigned to have either a CobraPLA^TM or a LMAU used for airway management using PCV. We compared the devices with respect to (i) ability to form an effective cuff seal, (ii) oxygenation, (iii) endtidal carbon dioxide level, (iv) time to achieve an effective airway, (v) airway interventions required for insertion, (vi) fiberoptic score, (vii) respiratory variables and (vii) adverse events. Results: Cuff seal pressure was significantly higher for CobraPLA^TM (27.08 ± 4.15 cmH₂O) than for LMAU (20.91 ± 2.47 cmH₂O). Oxygenation was similar in both groups while the mean endtidal CO₂ in the CobraPLA^TM group was significantly higher than in the LMAU group (36.47 ± 1.93 mmHg vs 34.71 ± 3.05 mmHg, P = 0.021). Time and ease of insertion were similar, with CobraPLA^TM requiring more frequent jaw lift and LMAU requiring more frequent adjustment of the head and neck to achieve a proper position. Fiberoptic scores were excellent with both devices. Respiratory variables were similar with the exception that the plateau pressure and mean peak pressures were significantly lower with CobraPLA^TM. There was a low rate of blood mucosal staining of the devices. No patient in either group reported a sore throat. Conclusions: Both devices appear to be safe and effective in establishing an adequate airway in healthy children undergoing surgery of short duration with PCV.     

Evaluating the ventilatory effect of transnasal humidified rapid insufflation ventilatory exchange in apnoeic small children with two different oxygen flow rates: a randomised controlled trial*

Transnasal humidified rapid insufflation ventilatory exchange prolongs safe apnoeic oxygenation time in children. In adults, transnasal humidified rapid insufflation ventilatory exchange is reported to have a ventilatory effect with PaCO₂ levels increasing less rapidly than without it. This ventilatory effect has yet to be reproduced in children. In this non-inferiority study, we tested the hypothesis that children weighing 10–15 kg exhibit no difference in carbon dioxide clearance when comparing two different high-flow nasal therapy flow rates during a 10-min apnoea period. Following standardised induction of anaesthesia including neuromuscular blockade, patients were randomly allocated to high-flow nasal therapy of 100% oxygen at 2 or 4 l.kg⁻¹.min⁻¹. Airway patency was ensured by continuous jaw thrust. The study intervention was terminated for safety reasons when SpO₂ values dropped < 95%, or transcutaneous carbon dioxide levels rose > 9.3 kPa, or near-infrared spectroscopy values dropped > 20% from their baseline values, or after an apnoeic period of 10 min. Fifteen patients were included in each group. In the 2 l.kg⁻¹.min⁻¹ group, mean (SD) transcutaneous carbon dioxide increase was 0.46 (0.11) kPa.min⁻¹, while in the 4 l.kg⁻¹.min⁻¹ group it was 0.46 (0.12) kPa.min⁻¹. The upper limit of a one-sided 95%CI for the difference between groups was 0.07 kPa.min⁻¹, lower than the predefined non-inferiority margin of 0.147 kPa.min⁻¹ (p = 0.001). The lower flow rate of 2 l.kg⁻¹.min⁻¹ was non-inferior to 4 l.kg⁻¹.min⁻¹ relative to the transcutaneous carbon dioxide increase. In conclusion, an additional ventilatory effect of either 2 or 4 l.kg⁻¹.min⁻¹ high-flow nasal therapy in apnoeic children weighing 10–15 kg appears to be absent.     

Flexible nasal bronchoscopy vs. Airtraq® videolaryngoscopy for awake tracheal intubation: a randomised controlled non-inferiority study

Videolaryngoscopy is a suitable alternative to flexible bronchoscopy to facilitate awake tracheal intubation. The relative effectiveness of these techniques in clinical practice is unknown. We compared flexible nasal bronchoscopy with Airtraq^® videolaryngoscopy in patients with an anticipated difficult airway scheduled for awake tracheal intubation. Patients were allocated randomly to flexible nasal bronchoscopy or videolaryngoscopy. All procedures were performed with upper airway regional anaesthesia blockade and a target-controlled intravenous infusion of remifentanil. The success rate with the allocated technique was the primary outcome. A non-inferiority analysis with a predefined limit of 8% was planned. Seventy-eight patients were recruited, allocated randomly and analysed. The rate of successful intubation was 97% and 82% in the flexible bronchoscopy and videolaryngoscopy groups, respectively, p = 0.032. The median (IQR [range]) time to tracheal intubation was shorter with the Airtraq, 163 (105–332 [40–1004]) vs. 217 (180–364 [120–780]) s, p = 0.030. There were no significant differences for complications found between the groups. The median visual analogue scale for ease of intubation was 8 (7–9 [0–10]) for Airtraq vs. 8 (7–9 [0–10]) for flexible bronchoscopy, p = 0.710. The median visual analogue scale for patient comfort for Airtraq was 8 (6–9 [2–10]) vs. 8 (7–9 [3–10]) for flexible bronchoscopy, p = 0.370. The Airtraq videolaryngoscope is not non-inferior to flexible bronchoscopy for awake tracheal intubation in a clinical setting when awake tracheal intubation is indicted. It may be a suitable alternative when judged on a case-by-case basis.     

The performance of rigid scopes for tracheal intubation: a randomised,controlled trial in patients with a simulated difficult airway

We compared the Bonfils^? and SensaScope^? rigid fibreoptic scopes in 200 patients with a simulated difficult airway randomised to one of the two devices. A cervical collar inhibited neck movement and reduced mouth opening to a mean (SD) of 23 (3) mm. The primary outcome parameter was overall success of tracheal intubation; secondary outcomes included first‐attempt success, intubation times, difficulty of intubation, fibreoptic view and side‐effects. The mean (95% CI) overall success rate was 88 (80–94)% for the Bonfils and 89 (81–94)% for the SensaScope (p = 0.83). First‐attempt intubation success rates were 63 (53–72)% for the Bonfils and 72 (62–81)% for the SensaScope (p = 0.17). Median (IQR [range]) intubation time was significantly shorter with the SensaScope (34 (20–84 [5–240]) s vs. 45 (25–134 [12–230]) s), and fibreoptic view was significantly better with the SensaScope (full view of the glottis in 79% with the SensaScope vs. 61% with the Bonfils). This might be explained by its steerable tip and the S‐formed shape, contributing to better manoeuvrability. There were no differences in the difficulty of intubation or side‐effects.     

Evaluation of three unchannelled videolaryngoscopes and the Macintosh laryngoscope in patients with a simulated difficult airway: a randomised,controlled trial

This prospective randomised, controlled trial compares the performance of three unchannelled videolaryngoscopes (KingVision^?, Airtraq^?, A.P. Advance^? MAC ) and the standard Macintosh laryngoscope. With ethics committee approval and written informed consent, 480 patients were included. A difficult airway was created with a cervical collar, limiting mouth opening and neck movement. Primary outcome was first‐attempt orotracheal intubation success. Overall success, laryngeal view, intubation difficulty scale, handling, intubation times and side‐effects were secondary outcomes. First‐attempt success rates were: KingVision 90% (95% CI 83–94%), Airtraq 82% (74–88%), A.P. Advance MAC 49% (40–58%), Macintosh 44% (35–53%; p < 0.001). The 95% confidence interval of first‐attempt success rate was thus below 90% for all devices, but the KingVision and the Airtraq performed better than the A.P. Advance MAC and the Macintosh laryngoscope. Also, performance was better with the KingVision and the Airtraq in terms of overall success, laryngeal view, intubation difficulty scale and quality of view. Problems with tube advancement were a frequent cause of intubation failure. In summary, the KingVision and the Airtraq performed better than the A.P. Advance MAC and the Macintosh laryngoscope. Success rates of the unchannelled KingVision and Airtraq were similar to those of their channelled versions reported previously, indicating that performance largely depends on blade design rather than the presence of a channel for tube advancement.     

A randomised,controlled trial evaluating a low cost, 3D‐printed bronchoscopy simulator

Low‐fidelity, simulation‐based psychomotor skills training is a valuable first step in the educational approach to mastering complex procedural skills. We developed a cost‐effective bronchial tree simulator based on a human thorax computed tomography scan using rapid‐prototyping (3D‐print) technology. This randomised, single‐blind study evaluated how realistic our 3D‐printed simulator would mimic human anatomy compared with commercially available bronchial tree simulators (Laerdal^® Airway Management Trainer with Bronchial Tree and AirSim Advance Bronchi, Stavanger, Norway). Thirty experienced anaesthetists and respiratory physicians used a fibreoptic bronchoscope to rate each simulator on a visual analogue scale (VAS) (0 mm = completely unrealistic anatomy, 100 mm = indistinguishable from real patient) for: localisation of the right upper lobe bronchial lumen; placement of a bronchial blocker in the left main bronchus; aspiration of fluid from the right lower lobe; and overall realism. The 3D‐printed simulator was rated most realistic for the localisation of the right upper lobe bronchial lumen (p = 0.002), but no differences were found in placement of a bronchial blocker or for aspiration of fluid (p = 0.792 and p = 0.057) compared with using the commercially available simulators. Overall, the 3D‐printed simulator was rated most realistic (p = 0.021). Given the substantially lower costs for the 3D‐printed simulator (£85 (€100/US$110) compared with > ~ £2000 (€2350/US$2590) for the commercially available simulators), our 3D‐printed simulator provides an inexpensive alternative for learning bronchoscopy skills, and offers the possibility of practising procedures on patient‐specific models before attempting them in clinical practice.     

Incidence and predictors of difficult laryngoscopy in 11.219 pediatric anesthesia procedures

Objective: Difficult laryngoscopy in pediatric patients undergoing anesthesia. Aim: This retrospective analysis was conducted to investigate incidence and predictors of difficult laryngoscopy in a large cohort of pediatric patients receiving general anesthesia with endotracheal intubation. Background: Young age and craniofacial dysmorphy are predictors for the difficult pediatric airway and difficult laryngoscopy. For difficult laryngoscopy, other general predictors are not yet described. Methods: Retrospectively, from a 5‐year period, data from 11.219 general anesthesia procedures in pediatric patients with endotracheal intubation using age‐adapted Macintosh blades in a single center (university hospital) were analyzed statistically. Results: The overall incidence of difficult laryngoscopy [Cormack and Lehane (CML) grade III and IV] was 1.35%. In patients younger than 1 year, the incidence of CML III or IV was significantly higher than in the older patients (4.7% vs 0.7%). ASA Physical Status III and IV, a higher Mallampati Score (III and IV) and a low BMI were all associated (P < 0.05) with difficult laryngoscopy. Patients undergoing oromaxillofacial surgery and cardiac surgery showed a significantly higher rate of CML III/IV findings. Conclusion: The general incidence of difficult laryngoscopy in pediatric anesthesia is lower than in adults. Our results show that the risk of difficult laryngoscopy is much higher in patients below 1 year of age, in underweight patients and in ASA III and IV patients. The underlying disease might also contribute to the risk. If the Mallampati score could be obtained, prediction of difficult laryngoscopy seems to be reliable. Our data support the existing recommendations for a specialized anesthesiological team to provide safe anesthesia for infants and neonates.     

Randomized controlled trial comparing the laryngeal tube and the laryngeal mask in pediatric patients

BACKGROUND: The laryngeal tube (LT) is a supraglottic ventilatory device used in adults. However, there is limited information about LT use in pediatric patients. This randomized controlled study compares LT with laryngeal mask (LMA) for airway management during spontaneous or assisted ventilation and during fiberoptic laryngoscopy in children. METHODS: Thirty children under 10-years old, ASA I-II, scheduled for minor general surgery, Mallampati score I-II, fasted and premedicated were included. Patients with upper respiratory infection, craniofacial malformation, intracranial hypertension, emergency surgery were excluded. The primary outcome measure was the proportion of patients in whom effective spontaneous or assisted ventilation [Vt > or = 4 ml.kg(-1), SpO2 > or = 95% with FiO2 0.4, P(E)CO2 < or = 7.2 kPa (55 mmHg)] was achieved after 3 min of LT or LMA cuff inflation. The secondary endpoint was the proportion of patients in whom fiberoptic laryngoscopy resulted in identification of the vocal cords. RESULTS: Eleven children with LMA and two children in LT group had adequate spontaneous or assisted ventilation after initial positioning (P < 0.01). After head extension or device repositioning 15 of 15 patients in LMA group had adequate ventilation compared with 11 of 15 patients in LT group (P < 0.05). The vocal cords could be observed with fiberoptic laryngoscopy in 11 LMA group patients compared with no patients in the LT group (P < 0.001). CONCLUSIONS: The LT is less effective than the LMA to allow adequate spontaneous or assisted ventilation and for fiberoptic evaluation of the airway in children under 10 years old.     

Non-invasive positive-pressure ventilation with positive end-expiratory pressure counteracts inward air leaks during preoxygenation: a randomised crossover controlled study in healthy volunteers

Background

During preoxygenation, the lack of tight fit between the mask and the patient's face results in inward air leak preventing effective preoxygenation. We hypothesized that non-invasive positive-pressure ventilation and positive end-expiratory pressure (PEEP) could counteract inward air leak.

Description and function of a difficult airway service

The goal of the Pediatric Difficult Airway Service (DAS) is to improve the care of children with airway abnormalities primarily through identification of children at risk for failed airway management. The airway service encourages early recognition and provides consultation, a plan for airway management, expertise in airway management, and follow‐up care for children who have a difficult airway. The service has improved the education of healthcare professionals and heightened awareness about the consequences of failed airway management.     

Anesthesia for shared airway surgery in children

Shared airway surgery in children is a complex, high‐risk undertaking that requires continuous communication and cooperation between the anesthetic and surgical teams. Airway abnormalities commonly seen in children, the surgical options, and the anesthetic techniques that can be used to care for this vulnerable population are discussed. Many of these procedures were traditionally carried out using jet ventilation, or intermittent tracheal intubation, but increasingly spontaneously breathing “tubeless” techniques are being used. This review has been written from both the surgical and anesthetic perspective, highlighting the concerns that both specialties have in relation to the maintenance of surgical access and operating conditions, and the need for the provision of anesthesia, oxygenation, and ventilation where the airway is the primary site of operation.     

The normal and the challenging pediatric airway

Management of a child’s airway is one of the main sources of stress for anesthetists who do not routinely anesthetize children. Unfortunately, trainees are gaining less experience in pediatric airway management than in the past, which is particularly difficult at a time when some beliefs about airway management are being challenged and airway management is less standardized. Fortunately, most children have an easily managed, normal airway. Nevertheless, it is of vital importance to teach our trainees the basic airway skills that are probably the most important skill in an anesthetists’ repertoire when it comes to a difficult airway situation. This review focuses on the airway management in children with a normal and a challenging airway. Different choices of airway management in children, and their advantages and disadvantages are discussed. Furthermore, the three broad causes of a challenging airway in children and infants are highlighted – the difficulty obtaining a mask seal, difficulty visualizing the vocal cords, and the third cause in which the larynx can be visualized but the difficulty lies at or beyond that level. Guidelines are given how to deal with these patients as well as with the feared but rare scenario of ‘cannot ventilate, cannot intubate’ in children.