Emergency ventilation with the Ventrain® through an airway exchange catheter in a porcine model of complete upper airway obstruction

In the Nick of Time-Emergency Front-of-Neck Airway Access

Emergency front-of-neck access refers to all techniques that deliver oxygen into the airway lumen through the anterior neck structures and encompasses access both through the cricothyroid membrane and the tracheal wall. There has yet to be a universal agreement regarding the preferred technique. A surgical incision is currently the most common approach in prehospital and in-hospital care. This review intends to review and summarize the existing clinical, basic science, and societal guidelines for eFONA.

Innovations in the Management of the Difficult Airway: A Narrative Review

The difficult airway (DA) remains a perpetual challenge and its implications have led to multiple advances, technological and otherwise in this area. This article investigates the latest developments in the definition, prediction tools and diagnostics like airway and neck Ultrasonography (USG), Magnetic Resonance Imaging (MRI) and Computed tomography (CT) scans, preoperative Virtual endoscopy (VE) and 3D printing. Innovations in airway devices and adjuncts are analysed. Difficult airway society (DAS) guidelines, American Society of Anaesthesiologists (ASA) Practice Guidelines and Vortex approach for the management of DA are explored. Other breakthroughs include novel oxygen supplementation techniques throughout airway management and tools like Anaesthesia Information Management Systems (AIMS) and Clinical Decision Support (CDS) systems. The delivery of DA training and patient counselling has also undergone vast changes with emerging technology like Virtual Reality (VR), mobile applications and toolkits. The enormous, ever-evolving and endless possibilities in this area have only helped improve clinical standards and enhance patient safety.

Ventilation through small-bore airways in children by implementing active expiration

Management of narrowed airways can be challenging, especially in the smallest patients. This educational review focusses on active expiration through small-bore airways with the Ventrain (Ventinova Medical, Eindhoven, The Netherlands). Manual ventilation with the Ventrain establishes inspiratory and expiratory flow control: By setting an appropriate flow, the volume of gas insufflated over time can be controlled and expiration through a small-bore airway is expedited by jet-flow generated suction, coined "expiratory ventilation assistance" (EVA). This overcomes the inherent risks of emergency jet ventilation especially in pediatric airway emergencies. Active expiration by EVA has been clinically introduced to turn a "straw in the airway" into a lifesaver allowing not only for quick and reliable reoxygenation but also adequate ventilation. As well as managing airway emergencies, ventilating through small-bore airways by applying EVA implements new options for pediatric airway management in elective interventional procedures. Safe application of EVA demands a thorough understanding of the required equipment, the principle and function of the Ventrain, technical prerequisites, clinical safety measures, and, most importantly, appropriate training.

Cuffed versus uncuffed tracheal tubes in a rabbit training model for establishing an emergency front-of-neck airway in infants: a prospective trial

BACKGROUND

There is a paucity of evidence regarding the optimal type of tracheal tube to be advanced over a Frova catheter when performing a 'bougie' emergency front-of-neck airway (eFONA) technique in infants during a 'cannot intubate, cannot oxygenate' situation.

METHODS

A prospective non-inferiority trial in a rabbit cadaver surgical tracheotomy model to assess the performance of the eFONA technique with an uncuffed 3.5 mm ID tracheal tube vs a cuffed 3.0 mm ID tracheal tube. Queried outcomes include success rate, performance time, and severe secondary airway injuries among tracheal tube types.

RESULTS

In 60 tracheostomies performed by 30 participants, the overall success rate was 98%. Performance time was independent from tracheal tube choice (uncuffed: 61 s [95% confidence interval (CI), 52-76], cuffed: 64 s [95% CI, 55-79]; P = 0.82). No tracheal tube type was preferred in terms of usability by participants. The cuffed tracheal tube required increased force to be advanced over the Frova catheter and was associated with a risk ratio of 2.5 (95% CI, 0.53-11.9; number needed to harm, 10) for severe secondary airway injuries when compared with the uncuffed tracheal tube.

CONCLUSION

In performing eFONA in the rabbit cadaver model, an ID 3.5 uncuffed is non-inferior to an ID 3.0 cuffed tracheal tube regarding performance time and preference by the operator. Greater force application to advance the cuffed tube over the Frova catheter and more severe airway injuries may argue for the standardised performance of the eFONA technique with a uncuffed tracheal tube in infants.

A special oropharyngeal oxygenation device to facilitate apneic oxygenation in comparison to high flow oxygenation devices

Oxygen application and apneic oxygenation may reduce the risk of hypoxemia due to apnea during awake fiberoptic intubation or failed endotracheal intubation. High flow devices are recommended, but their effect compared to moderate deep oropharyngeal oxygen application is unknown. Designed as an experimental manikin trial, we made a comparison between oxygen application via nasal prongs at 10 L/min (control group), applying oxygen via oropharyngeal oxygenation device (at 10 L/min), oxygen application via high flow nasal oxygen with 20 L/min and 90% oxygen (20 L/90% group), oxygen application via high flow nasal oxygen with 60 L/min and 45% oxygen (60 L/45% group), and oxygen application via sealed face mask with a special adapter to allow for fiberoptic entering of the airway. We preoxygenated the lung of a manikin and measured the decrease in oxygen level during the following 20 minutes for each way of oxygen application. Oxygen levels fell from 97 ± 1% at baseline to 75 ± 1% in control group, and to 86 ± 1% in oropharyngeal oxygenation device group. In the high flow nasal oxygen group, oxygen level dropped to 72 ± 1% in the 20 L/90% group and to 44 ± 1% in the 60 L/45% group. Oxygen level remained at 98 ± 0% in the face mask group. In conclusion, in this manikin simulation study of apneic oxygenation, oxygen insufflation using a sealed face mask kept oxygen levels in the test lung at 98% over 20 minutes, oral oxygenation device led to oxygen levels at 86%, whereas all other methods resulted in the decrease of oxygen levels below 75%.

Ventilation strategies for front of neck airway rescue: an in silico study

BACKGROUND

During induction of general anaesthesia a 'cannot intubate, cannot oxygenate' (CICO) situation can arise, leading to severe hypoxaemia. Evidence is scarce to guide ventilation strategies for small-bore emergency front of neck airways that ensure effective oxygenation without risking lung damage and cardiovascular depression.

METHODS

Fifty virtual subjects were configured using a high-fidelity computational model of the cardiovascular and pulmonary systems. Each subject breathed 100% oxygen for 3 min and then became apnoeic, with an obstructed upper airway. When arterial haemoglobin oxygen saturation reached 40%, front of neck airway access was simulated with various configurations. We examined the effect of several ventilation strategies on re-oxygenation, pulmonary pressures, cardiovascular function, and oxygen delivery.

RESULTS

Re-oxygenation was achieved in all ventilation strategies. Smaller airway configurations led to dynamic hyperinflation for a wide range of ventilation strategies. This effect was absent in airways with larger internal diameter (≥3 mm). Intrapulmonary pressures increased quickly to supra-physiological values with the smallest airways, resulting in pronounced cardio-circulatory depression (cardiac output <3 L min^-1 and mean arterial pressure <60 mm Hg), impeding oxygen delivery (<600 ml min^-1). Limiting tidal volume (≤200 ml) and ventilatory frequency (≤8 bpm) for smaller diameter cannulas reduced dynamic hyperinflation and gas trapping, preventing cardiovascular depression.

CONCLUSIONS

Dynamic hyperinflation can be demonstrated for a wide range of front of neck airway cannulae when the upper airway is obstructed. When using small-bore cannulae in a CICO situation, ventilation strategies should be chosen that prevent gas trapping to prevent severe adverse events including cardio-circulatory depression.

Rabbit training model for establishing an emergency front of neck airway in children

BACKGROUND

A 'cannot intubate, cannot oxygenate' (CICO) situation is rare in paediatric anaesthesia, but can always occur in children under certain emergency situations. There is a paucity of literature on specific procedures for securing an emergency invasive airway in children younger than 6 yr. A modified emergency front of neck access (eFONA) technique using a rabbit cadaver model was developed to teach invasive airway protection in a CICO situation in children.

METHODS

After watching an instructional video of our eFONA technique (tracheotomy, intubation with Frova catheter over which a tracheal tube is inserted), 29 anaesthesiologists performed two separate attempts on rabbit cadavers. The primary outcome was the success rate and the performance time overall and in subgroups of trained and untrained participants.

RESULTS

The overall success rate across 58 tracheotomies was 95% and the median performance time was 67 s (95% confidence interval [CI], 56-76). Performance time decreased from the first to the second attempt from 72 s (95% CI, 57-81) to 61 s (95% CI, 50-81). Performance time was 59 s (95% CI, 49-79) for untrained participants and 72 s (95% CI, 62-81) for trained participants. Clinical experience and age of the participants was not correlated with performance time, whereas the length of the tracheotomy incision showed a significant correlation (P=0.006).

CONCLUSION

This eFONA training model for children facilitates rapid skill acquisition under realistic anatomical conditions to perform an emergency invasive airway in children younger than 2 yr.

Emerging trends, techniques, and equipment for airway management in pediatric patients

Pediatric patients present unique anatomic and physiologic considerations in airway management, which impose significant physiologic limits on safe apnea time before the onset of hypoxemia and subsequent bradycardia. These issues are even more pronounced for the pediatric difficult airway. In the last decade, the development of pediatric sized supraglottic airways specifically designed for intubation, as well as advances in imaging technology such that current pediatric airway equipment now finally rival those for the adult population, has significantly expanded the pediatric anesthesiologist's tool kit for pediatric airway management. Equally important, techniques are increasingly implemented that maintain oxygen delivery to the lungs, safely extending the time available for pediatric airway management. This review will focus on emerging trends and techniques using existing tools to safely handle the pediatric airway including videolaryngoscopy, combination techniques for intubation, techniques for maintaining oxygenation during intubation, airway management in patients at risk for aspiration, and considerations in cannot intubate cannot oxygenate scenarios.

Manual volume delivery via Frova Intubating Introducer: a bench research study

PURPOSE

Oxygen delivery through a Frova Intubating Introducer may be life-saving, and gas flow characteristics through this device have been described. Nevertheless, the feasibility of using a self-inflating resuscitation bag to deliver air or oxygen through this device has not been assessed. We compared volumes of air delivered and peak pressures generated with normal and maximal bimanual compression of a self-inflating resuscitation bag connected to a 70 cm Frova Intubating Introducer.

METHODS

In this bench research study, the proximal end of the 14-F Frova Intubating Introducer was connected to the self-inflating resuscitation bag, and the distal end was connected to a flow analyzer fitted with an adult test lung. Thirty-five anesthesia health care providers (staff/trainees) squeezed the self-inflating resuscitation bag with three normal and three maximal bimanual compressions. Endpoints of interest included the delivered volume of air and generated peak pressure.

RESULTS

Normal bimanual compression resulted in a smaller mean (standard deviation) volume of air and peak pressure compared with maximal bimanual compression [554 (131) vs 955 mL (121); mean difference - 400.4; 95% confidence interval [CI], - 441.8 to - 359.0; P < 0.001; and 22.0 (3.4) vs 41.8 cmH₂O (13.3); mean difference - 19.7; 95% CI, - 23.5 to - 15.9; P < 0.001, respectively].

CONCLUSION

Clinically useful, life-sustaining volumes of air can be delivered using normal and maximal bimanual compression of a self-inflating resuscitation bag connected to a 70 cm Frova Intubating Introducer.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT02786355); registered 27 January, 2016.

The Difficult Airway Trolley: A Narrative Review and Practical Guide

Death and severe morbidity attributable to anesthesia are commonly associated with failed difficult airway management. When an airway emergency develops, immediate access to difficult airway equipment is critical for implementation of rescue strategies. Previously, national expert consensus guidelines have provided only limited guidance for the design and setup of a difficult airway trolley. The overarching aim of the current work was to create a dedicated difficult airway trolley (for patients>12 years old) for use in anesthesia theatres, intensive care units, and emergency departments. A systematic literature search was performed, using the PubMed, Embase, and Google Scholar search engines. Based on evidence presented in 11 national or international guidelines, and peer-reviewed journals, we present and outline a difficult airway trolley organized to accommodate sequential progression through a four-step difficult airway algorithm. The contents of the top four drawers correspond to specific steps in the airway algorithm (A = intubation, B = oxygenation via a supraglottic airway device, C = facemask ventilation, and D = emergency invasive airway access). Additionally, specialized airway equipment may be included in the fifth drawer of the proposed difficult airway trolley, thus enabling widespread use. A logically designed, guideline-based difficult airway trolley is a vital resource for any clinician involved in airway management and may aid the adherence to difficult airway algorithms during evolving airway emergencies. Future research examining the availability of rescue airway devices in various clinical settings, and simulation studies comparing different types of difficult airway trolleys, are encouraged.

Transtracheal Use of the CriCath Cannula in Combination With the Ventrain Device for Prevention of Hypoxic Arrest due to Severe Upper Airway Obstruction: A Case Report

A patient recently treated with surgery and radiation for oropharyngeal cancer presented with impending hypoxic respiratory and cardiac arrest in a difficult airway scenario. A CriCath cannula in combination with the Ventrain device and its active expiratory ventilation technology enabled oxygenation and ventilation for 60 minutes until a surgical airway was established. This case report is the first to describe the intended use of Ventrain technology in an emergent "can't ventilate-can't intubate" scenario.

A prototype small-bore ventilation catheter with a cuff: cuff inflation optimizes ventilation with the Ventrain

Background

Ventilation through small‐diameter tubes typically precludes use of a cuff as this will impede the necessary passive outflow of gas alongside the tube's outer surface. Ventrain assists expiration and enables oxygenation and normoventilation through small‐bore cannulas or catheters, particularly in obstructed airways. A small‐bore ventilation catheter (SBVC; 40 cm long, 2.2 mm inner diameter) with a separate pressure monitoring lumen and a cuff was developed. Efficacy of oxygenation and ventilation with Ventrain through this catheter was investigated in sealed and open airways in a porcine cross‐over study.

Methods

Six pigs were ventilated with Ventrain (15 l/min oxygen, frequency 30 breaths per min, I : E‐ratio 1 : 1) through the SBVC, both with the cuff inflated and deflated. Prior to each test they were ventilated conventionally until steady state was achieved.

Results

With an inflated cuff, PaO₂ rose instantly and remained elevated (median [range] PaO₂ 61 [52–69] kPa after 30 min; P = 0.027 compared to baseline). PaCO₂ remained stable at 4.9 [4.2–6.2] kPa. After cuff deflation, PaO₂ was significantly lower (9 [5–28] kPa at 10 min, P = 0.028) and interventional ventilation had to be stopped prematurely in five pigs as PaCO₂ exceeded 10.6 kPa. Pulmonary artery pressures increased markedly in these pigs. Intratracheal pressures were kept between 5 and 20 cmH₂O with the cuff inflated, but never exceeded 2 cmH₂O after cuff deflation.

Conclusion

The SBVC combines the benefits of a small diameter airway and a cuff. Cuff inflation optimizes oxygenation and ventilation with Ventrain.

Ventilation via the 2.4 mm internal diameter Tritube® with cuff - new possibilities in airway management

BACKGROUND

A small tube may facilitate tracheal intubation and improve surgical access. We describe our initial experience with the Tritube^® that is a novel cuffed endotracheal tube with a 2.4 mm internal diameter.

METHODS

The Tritube^® was used in seven adult Ear-Nose-and Throat surgical patients with airway narrowing or whose surgical access was facilitated by this small-bore endotracheal tube. Ventilation through Tritube^® is performed with the manually operated Ventrain^® -ventilator that allows active suctioning during expiration, therefore facilitating normoventilation through small diameter airways.

RESULTS

The small diameter of Tritube^® seemed to improve glottis visualisation during intubations and gave excellent working conditions for surgery. Two patients were intubated awake with a flexible scope and a guide wire or with an angulated video laryngoscope. One patient had almost complete glottic occlusion that just allowed for passage of the Tritube^® . Adequate ventilation was achieved in all patients and intratracheal pressure was kept between 5 and 20 cm H₂ O. The tube was well tolerated after emergence from anaesthesia and kept intratracheally in five awake patients in the post-operative recovery unit, in one case for more than 1 h. Ventilating with Ventrain^® through Tritube^® demands meticulous breath by breath measurement and adjustment of the intratracheal pressure.

CONCLUSION

The 2.4 mm internal diameter Tritube^® seems to facilitate tracheal intubation and to provide unprecedented view of the intubated airway during oral, pharyngeal, laryngeal or tracheal procedures in adults. This technique has the potential to replace temporary tracheostomy, jet-ventilation or extra-corporal membrane oxygenation in selected patients.