Difficult airway management for the anaesthetist

Identification of difficult laryngoscopy using an optimized hybrid architecture

BACKGROUND

Identification of difficult laryngoscopy is a frequent demand in cervical spondylosis clinical surgery. This work aims to develop a hybrid architecture for identifying difficult laryngoscopy based on new indexes.

METHODS

Initially, two new indexes for identifying difficult laryngoscopy are proposed, and their efficacy for predicting difficult laryngoscopy is compared to that of two conventional indexes. Second, a hybrid adaptive architecture with convolutional layers, spatial extraction, and a vision transformer is proposed for predicting difficult laryngoscopy. The proposed adaptive hybrid architecture is then optimized by determining the optimal location for extracting spatial information.

RESULTS

The test accuracy of four indexes using simple model is 0.8320. The test accuracy of optimized hybrid architecture using four indexes is 0.8482.

CONCLUSION

The newly proposed two indexes, the angle between the lower margins of the second and sixth cervical spines and the vertical direction, are validated to be effective for recognizing difficult laryngoscopy. In addition, the optimized hybrid architecture employing four indexes demonstrates improved efficacy in detecting difficult laryngoscopy.

TRIAL REGISTRATION

Ethics permission for this research was obtained from the Medical Scientific Research Ethics Committee of Peking University Third Hospital (IRB00006761-2015021) on 30 March 2015. A well-informed agreement has been received from all participants. Patients were enrolled in this research at the Chinese Clinical Trial Registry ( http://www.chictr.org.cn , identifier: ChiCTR-ROC-16008598) on 6 June 2016.

The Heimlich maneuver and chest compression relieve mask ventilation difficulties caused by asymptomatic laryngeal mass: A case report and review of literature

RATIONALE

Some laryngeal masses are typically asymptomatic and easily ignored. However, they can be rare causes of unanticipated difficult airway, leading to critical situations such as "cannot ventilate" or "cannot ventilate and cannot intubate" during anesthesia induction. Inappropriate airway management in such scenarios can have catastrophic consequences for an anesthetized patient. Here we report a case of sudden, unanticipated difficult mask ventilation caused by an asymptomatic supraglottic mass during sedative induction, which was quickly and effectively relieved by the Heimlich maneuver and chest compression.

PATIENT CONCERNS

We report a rare case of airway crisis occurred during sedative induction in a 63-year-old patient scheduled for a routine flexible bronchoscopy, and no evidence of respiratory difficulty or signs of obstruction was found in preoperative evaluation.

DIAGNOSES

A detailed examination of laryngopharyngeal structure under bronchoscopy revealed a supraglottic soft-tissue mass with a size of 1.6 × 0.8 cm covering the membranous part of the glottic area, which was the true cause of difficult mask ventilation in this patient during sedative induction.

INTERVENTIONS

As the unanticipated difficult mask ventilation occurred, 2-handed mask ventilation was initiated immediately for 9 attempts but failed. Fortunately, the airway crisis was successfully relieved with 2 Heimlich attempts and 3 chest compressions, and no need for a laryngeal mask airway.

OUTCOMES

Once the airway crisis was relieved and the supraglottic mass was confirmed, the patient underwent a second sedative anesthesia and a successful laryngeal mask airway-assisted bronchoscopy, with no post-bronchoscopy adverse events.

LESSONS

Asymptomatic supraglottic masses can cause valve-like upper airway obstruction and lead to unanticipated difficult mask ventilation. The Heimlich maneuver and chest compression may be effective in such critical situations and can serve as an emergency intervention.

Utilization of submandibular ultrasound to measure oral cavity changes with interventions in routine airway management

Ultrasound is a quick, noninvasive, inexpensive tool that can provide an accurate airway assessment. Tongue thickness, oral cavity height, and their relationship were measured using submandibular ultrasonography with and without oral airway interventions during intubation in 26 patients. The mean tongue thickness to oral cavity height ratio was 0.83 ± 0.03. The percent change of tongue thickness to oral cavity height decreased significantly by 36.47% with an oral airway and by 43.49% with laryngoscope interventions (P < 0.01). This study demonstrates how ultrasound-measured oral cavity ratios change with the placement of airway equipment, and application of these findings may advance our understanding of advanced airway management among diverse patient populations.

Conversion of an oral to nasal intubation in difficult nasal anatomy patients: two case reports

Background

Nasal intubation is indispensable for some cases that require intraoral surgical access, and the fiberoptic bronchoscope is the best tool for difficult airways. However, fiberoptic bronchoscopy is not always possible in cases with altered pharyngeal anatomy.

Case presentation

In this report, we introduce a novel technique for retrograde endotracheal oral-to-nasal conversion with an ordinary endotracheal tube exchange catheter. A 49-year-old male with a fractured mandible angle and symphysis was scheduled to undergo mandible reconstruction. Secondly, a 45-year-old male who had a bone defect in the mandible angle and ramus was scheduled for mandible and oral cavity reconstruction. We chose to intubate orally first and successfully converted the endotracheal tube from oral to nasal retrogressively using a tube exchange catheter.

Conclusions

Our simple and safe technique, which use a tube exchange catheter retrogressively, provides an alternative method for a difficult airway in which the fiberscope is not helpful.

Radiological indicators to predict the application of assistant intubation techniques for patients undergoing cervical surgery

Background

We aimed to distinguish the preoperative radiological indicators to predict the application of assistant techniques during intubation for patients undergoing selective cervical surgery.

Methods

A total of 104 patients were enrolled in this study. According to whether intubation was successfully accomplished by simple Macintosh laryngoscopy, patients were divided into Macintosh laryngoscopy group (n = 78) and Assistant technique group (n = 26). We measured patients’ radiographical data via their preoperative X-ray and MRI images, and compared the differences between two groups. Binary logistic regression model was applied to distinguish the meaningful predictors. Receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to describe the discrimination ability of indicators. The highest Youden’s index corresponded to an optimal cut-off value.

Results

Ten variables exhibited significant statistical differences between two groups (P <  0.05). Based on logistic regression model, four further showed correlation with the application of assistant techniques, namely, perpendicular distance from hard palate to tip of upper incisor (X2), atlanto-occipital gap (X9), angle between a line passing through posterior-superior point of hard palate and the lowest point of the occipital bone and a line passing through the anterior-inferior point and the posterior-inferior point of the second cervical vertebral body (Angle E), and distance from skin to hyoid bone (MRI 7). Angle E owned the largest AUC (0.929), and its optimal cut-off value was 19.9° (sensitivity = 88.5%, specificity = 91.0%). the optimal cut-off value, sensitivity and specificity of other three variables were X2 (30.1 mm, 76.9, 76.9%), MRI7 (16.3 mm, 69.2, 87.2%), and X9 (7.3 mm, 73.1, 56.4%).

Conclusions

Four radiological variables possessed potential ability to predict the application of assistant intubation techniques. Anaesthesiologists are recommended to apply assistant techniques more positively once encountering the mentioned cut-off values.