Randomised comparison of Enk™ and Manujet™ for emergency tracheal oxygenation with a high-fidelity full-scale simulation

BACKGROUND

We aimed to compare time and difficulties of emergency tracheal oxygenation with Enk™ or Manujet™ by anaesthesiologists or intensivists, in a full-scale cannot ventilate and intubate scenarios on a SimMan3G™ high-fidelity patient simulator.

METHODS

After ethical committee approval and written informed consent, teams (two to three learners with at least one physician senior) participating at a difficult airway training with a massive sublingual haematoma scenario, were randomised in Enk™ (E) group (29 teams, 76 learners) and Manujet™ (M) group (31 teams, 84 learners) according to the device at disposal. Main criterion was time between taking device in hand and first insufflation delay. Data were medians [25-75%].

RESULTS

The handling-insufflation time was shorter with Enk™ than with Manujet™ (74 [54-87] seconds versus 95 [73-123] seconds (s), P=0.0112). The team number performing insufflation within one minute after device handling was higher in the E group (8, 27.6%) than in the M group (2, 6.4%) (P=0.0392) as well as the team number performing insufflation within 90s in the E group (22, 75.09%) than in the M group (12, 38.7%) (P=0.0047). In E group, 75% of learners reported no difficulty versus 58.8% in M group (P=0.0443). Insufflation frequency was high in both groups and higher than 12min^-1 in 51.7% of the teams.

CONCLUSION

In a simulation context, Enk™ use is faster and easier. A high insufflation rate was also in favour of Enk™ that generates lower airway pressures.

Rescue oxygenation success by cannula or scalpel-bougie emergency front-of-neck access in an anaesthetised porcine model

In the obese, the evidence for the choice of the optimal emergency front-of-neck access technique is very limited and conflicting. We compared cannula and scalpel-bougie emergency front-of-neck access techniques in an anaesthetised porcine model with thick pretracheal tissue. Cannula and scalpel-bougie cricothyroidotomy techniques were performed in 11 and 12 anaesthetised pigs, respectively. Following successful tracheal access, oxygenation was commenced and continued for 5 min using Rapid-O2 device for cannula and circle breathing system for scalpel-bougie study groups. The primary outcome was a successful rescue oxygenation determined by maintenance of arterial oxygen saturation >90% 5 min after the beginning of oxygenation. Secondary outcomes included success rate of airway device placement, time to successful airway device placement, and trauma to the neck and airway. The success rate of rescue oxygenation was 18% after cannula, and 83% after scalpel-bougie technique (P = 0.003). The success rate of airway device placement was 73% with cannula and 92% with scalpel-bougie technique (P = 0.317). Median (inter-quartile-range) times to successful airway device placement were 108 (30–256) and 90 (63–188) seconds (P = 0.762) for cannula and scalpel-bougie emergency front-of-neck access, respectively. Proportion of animals with iatrogenic trauma additional to the procedure itself was 27% for cannula and 75% for scalpel-bougie technique (P = 0.039). Thus, in the porcine model of obesity, the scalpel-bougie technique was more successful in establishing and maintaining rescue oxygenation than cannula-based technique; however, it was associated with a higher risk of severe trauma.

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.

Use of a trans-tracheal rapid insufflation of oxygen device in a "cannot intubate, cannot oxygenate" scenario in a parturient -a case report

Background

The trans-tracheal rapid insufflation of oxygen (TRIO) device is less commonly used and is an alternative to trans-tracheal jet ventilation for maintaining oxygenation in a "cannot intubate, cannot oxygenate" (CICO) scenario.

Case

We report the successful use of this device to maintain oxygenation after jet ventilator failure in a parturient who presented with the CICO scenario during the procedure for excision of laryngeal papilloma.

Conclusions

A stepwise approach to the airway plan and preparation for an event of failure is essential for good materno-fetal outcomes. The TRIO device may result in inadequate ventilation that can lead to hypercarbia and respiratory acidosis. Hence, it should only be used as a temporizing measure before a definitive airway can be secured.

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.

Improved lung recruitment and oxygenation during mandatory ventilation with a new expiratory ventilation assistance device: A controlled interventional trial in healthy pigs

BACKGROUND

In contrast to conventional mandatory ventilation, a new ventilation mode, expiratory ventilation assistance (EVA), linearises the expiratory tracheal pressure decline.

OBJECTIVE

We hypothesised that due to a recruiting effect, linearised expiration oxygenates better than volume controlled ventilation (VCV). We compared the EVA with VCV mode with regard to gas exchange, ventilation volumes and pressures and lung aeration in a model of peri-operative mandatory ventilation in healthy pigs.

DESIGN

Controlled interventional trial.

SETTING

Animal operating facility at a university medical centre.

ANIMALS

A total of 16 German Landrace hybrid pigs.

INTERVENTION

The lungs of anaesthetised pigs were ventilated with the EVA mode (n=9) or VCV (control, n=7) for 5 h with positive end-expiratory pressure of 5 cmH2O and tidal volume of 8 ml kg. The respiratory rate was adjusted for a target end-tidal CO2 of 4.7 to 6 kPa.

MAIN OUTCOME MEASURES

Tracheal pressure, minute volume and arterial blood gases were recorded repeatedly. Computed thoracic tomography was performed to quantify the percentages of normally and poorly aerated lung tissue.

RESULTS

Two animals in the EVA group were excluded due to unstable ventilation (n=1) or unstable FiO2 delivery (n=1). Mean tracheal pressure and PaO2 were higher in the EVA group compared with control (mean tracheal pressure: 11.6 ± 0.4 versus 9.0 ± 0.3 cmH2O, P < 0.001 and PaO2: 19.2 ± 0.7 versus 17.5 ± 0.4 kPa, P = 0.002) with comparable peak inspiratory tracheal pressure (18.3 ± 0.9 versus 18.0 ± 1.2 cmH2O, P > 0.99). Minute volume was lower in the EVA group compared with control (5.5 ± 0.2 versus 7.0 ± 1.0 l min, P = 0.02) with normoventilation in both groups (PaCO2 5.4 ± 0.3 versus 5.5 ± 0.3 kPa, P > 0.99). In the EVA group, the percentage of normally aerated lung tissue was higher (81.0 ± 3.6 versus 75.8 ± 3.0%, P = 0.017) and of poorly aerated lung tissue lower (9.5 ± 3.3 versus 15.7 ± 3.5%, P = 0.002) compared with control.

CONCLUSION

EVA ventilation improves lung aeration via elevated mean tracheal pressure and consequently improves arterial oxygenation at unaltered positive end-expiratory pressure (PEEP) and peak inspiratory pressure (PIP). These findings suggest the EVA mode is a new approach for protective lung ventilation.

Ventrain: from theory to practice. Bridging until re-tracheostomy

Imminent upper airway obstruction due to life-threatening tracheal stenosis of any cause is challenging. A 77-year-old woman, with a history of temporal tracheostomy for prolonged mechanical ventilation, presented with life-threatening tracheal stenosis to the emergency department. After failed intubation with a 5.0 mm internal diameter endotracheal tube, the patient was ventilated via a tube exchanger using Ventrain. Ventrain is a manual ventilation device that, in addition to oxygen supply during inspiration, initiates expiration by actively removing gas from the lungs by suction. Despite the nearly obstructed airway the patient was adequately ventilated with 'permissive' hypercarbia of 50 mm Hg and Saturation of peripheral Oxygen (SpO₂) 95%-98% until surgical re-tracheostomy was performed. The haemodynamic stability of the patient indicated that the active expiration prevented intrapulmonary pressure build-up by air trapping and subsequent barotrauma and/or haemodynamic deterioration, which may well be observed during traditional jet ventilation especially in case of a completely obstructed airway.

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.

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

Purpose

During difficult airway management, oxygen insufflation through airway-exchange and intubating catheters (AEC/IC) can lead to life-threatening hyperinflation. Ventrain^® was originally designed to facilitate emergency ventilation using active expiration through short, small-bore cannulas. Herein, we studied its efficacy (oxygenation and ventilation) and safety (avoidance of hyperinflation) in a long, small-bore AEC.

Methods

In six anesthetized pigs, the upper airway was obstructed, except for a 100 cm long, 3 mm internal diameter AEC. After apneic desaturation to a peripheral oxygen saturation (SpO₂) of < 70%, ventilation through the AEC was started with Ventrain at an oxygen flow of 15 L·min⁻¹, a frequency of 30 breaths·min⁻¹, and an inspiration/expiration ratio of approximately 1:1. It was continued for ten minutes.

Results

Within one minute, severe hypoxia was reversed from a median [interquartile range] arterial saturation (SaO₂) of 48 [34-56] % before initiation of Ventrain ventilation to 100 [99-100] % afterward (median difference 54%; 95% confidence interval [CI] 44 to 67; P = 0.028). In addition, hypercarbia was reversed from PaCO₂ of 59 [53-61] mmHg to 40 [38-42] mmHg (median difference of −18 mmHg; 95% CI −21 to −15; P = 0.028). After ten minutes of Ventrain use, peak inspiratory and end-expiratory pressures were lower than during baseline pressure-controlled ventilation (8 [7-9] mmHg vs 12 [10-14] mmHg and −2 [−3 to +1] mmHg vs 4 [2 to 4] mmHg, respectively; P = 0.027 for both). No hemodynamic deterioration occurred.

Conclusion

Ventrain provides rapid reoxygenation and effective ventilation through a small-bore AEC in pigs with an obstructed airway. In clinical emergency situations of obstructed airways, this device may be able to overcome problems of unintentional hyperinflation and high intrapulmonary pressures when ventilating through long, small-bore catheters and could therefore minimize the risks of barotrauma and hemodynamic instability.

[Monitoring tidal volumes when using the Ventrain® emergency ventilator]

BACKGROUND

The Ventrain® emergency ventilation device allows active inspiration and expiration through transtracheal catheters or the lumen of an airway exchange catheter. This single-use handheld device is manually operated and driven by an external pressurized oxygen source. The Ventrain® may be used to ventilate patients with a complete or pending upper airway obstruction reducing the risk of barotrauma due to the possibility of active expiration. However tidal volumes (V T) applied and withdrawn with the Ventrain® can only be controlled by visual inspection of chest movements; V T monitoring is not provided. Excessive inspiratory volumes or air trapping due to insufficient expiration may remain clinically undetected until pulmonary trauma and/or cardio-respiratory deterioration occur. Active expiration itself carries the risk of overwhelming lung deflation with the formation of atelectasis. Thus, an inspiratory and expiratory tidal volume monitor is urgently required. The aim of this study was to evaluate efficacy and precision of the Florian respiratory function monitor (RFM) to monitor in- and expiratory V T administered by the Ventrain® emergency ventilation device through a small cannula to the ASL 5000 test lung (ASL).

METHODS

In an in-vitro setting the RFM was used with its neonatal flow sensor to monitor inspiratory and expiratory V T applied by the Ventrain® emergency ventilation device through a 2 mm internal diameter (ID) transtracheal catheter to the ASL. Driving flows of 6, 9, 12 and 15 l min(-1) were chosen to vary tidal volumes at a constant respiratory rate of 15 min(-1) and an I:E ratio of 1:1. Experiments were repeated five times with two flow sensors. An initial set-up calibration run was performed to calculate a bias correction factor for inspiratory and expiratory V T measured by the RFM. This bias correction factor was used to simulate a correction of the in the RFM programmed linearization table. In a second, identical setting the experiments were repeated five times with two flow sensors. V T measured by the adjusted RFM were compared with those obtained from the ASL 5000 in this second run and the percentage differences were calculated. Bland Altman analysis was used to investigate the agreement of inspiratory or expiratory VT measured by both methods (ASL and RFM). Calculation of the mean of differences between both methods is given as bias and the 95 % agreement interval as precision.

RESULTS

Tidal volumes measured by the ASL ranged from 140 to 675 ml. The percentage correction factor was 16.27 % (2.60 %) during inspiration for V T ranged from 0 to 700 ml and 11.51 % (2.56 %) during expiration for V T of 0 to 225 ml, 7.41 % (2.94 %) for VT 226 to 325 ml and 5.35 % (3.57 %) for TV e > 325 ml. Inspiratory and expiratory tidal volumes measured by the adjusted RFM demonstrated a percentage deviation (mean [SD]) of 2.59 % (1.86 %) during inspiration and 1.66 % (1.14 %) during expiration when compared with the ASL 5000. Bias (precision) of the Bland Altman plot for the adjusted RFM is 2.05 ml (23.20) during inspiration and 4.62 ml (10.40) for expiration.

CONCLUSION

The tested respiratory function monitor using hot-wire anemometer technology has the potential to monitor tidal volumes applied by the Ventrain®. With the software thus adapted, the RFM measures precise inspiratory and expiratory tidal volumes within common technical tolerance. This could help perform adequate patient ventilation with Ventrain® and reduce the potential risk of patient trauma.

Impact of oxygen sources on performance of the Ventrain(®) ventilation device in an in vitro set-up

BACKGROUND

The Ventrain(®) (Dolphys Medical, Eindhoven, The Netherlands) is a disposable handheld ventilation device allowing active inspiration and expiration through a transtracheal catheter. This study investigated Ventrain(®) 's performance when used with different clinical oxygen sources in an in vitro set-up.

METHODS

Three anesthesia oxygen sources (wall-mounted flowmeter, respirator oxygen outlet port, and anesthesia ventilator circuit) were used at gas flow rates of 6, 9, 12, and 15 l/min. First, the sources' driving pressures (DP), the insufflation pressure (IP), and the flow at the catheter tip were measured using a gas flow analyzer. Tidal volumes (VT) delivered by the Ventrain(®) were assessed by the ASL5000 test lung (respiratory rate: 15 min(-1), I:E = 1:1, compliance: 100 ml/cmH2O, resistance: 3.06 cmH2O/l/s).

RESULTS

VT ranged from 82 to 483 ml for inspiration and 82 to 419 ml for expiration. Measured IP, flow, and VT were less dependent on the set gas flow rate but more on the source's DP. With rising DP the IP, the flow at the catheter tip and consequently VT increased. At an approximate target I:E ratio of 1:1, the ratio of inspiratory to expiratory VT increased with higher DP and gas flow rates.

CONCLUSION

The oxygen sources resulted in clinically different IP, flows, and VT delivered by the Ventrain(®) at given gas flow rates. This needs to be considered in a clinical emergency situation. Integrating an adjustable pressure valve into Ventrain(®) to allow regulation of the lowest necessary IP would make its use safer.

Pulmonary effects of expiratory-assisted small-lumen ventilation during upper airway obstruction in pigs

Novel devices for small-lumen ventilation may enable effective inspiration and expiratory ventilation assistance despite airway obstruction. In this study, we investigated a porcine model of complete upper airway obstruction. After ethical approval, we randomly assigned 13 anaesthetised pigs either to small-lumen ventilation following airway obstruction (n = 8) for 30 min, or to volume-controlled ventilation (sham setting, n = 5). Small-lumen ventilation enabled adequate gas exchange over 30 min. One animal died as a result of a tension pneumothorax in this setting. Redistribution of ventilation from dorsal to central compartments and significant impairment of the distribution of ventilation/perfusion occurred. Histopathology demonstrated considerable lung injury, predominantly through differences in the dorsal dependent lung regions. Small-lumen ventilation maintained adequate gas exchange in a porcine airway obstruction model. The use of this technique for 30 min by inexperienced clinicians was associated with considerable end-expiratory collapse leading to lung injury, and may also carry the risk of severe injury.

Transtracheal ventilation with a novel ejector-based device (Ventrain) in open, partly obstructed, or totally closed upper airways in pigs

BACKGROUND

Transtracheal access and subsequent jet ventilation are among the last options in a 'cannot intubate-cannot oxygenate' scenario. These interventions may lead to hypercapnia, barotrauma, and haemodynamic failure in the event of an obstructed upper airway. The aim of the present study was to evaluate the efficacy and the haemodynamic effects of the Ventrain, a manually operated ventilation device that provides expiratory ventilation assistance. Transtracheal ventilation was carried out with the Ventrain in different airway scenarios in live pigs, and its performance was compared with a conventional jet ventilator.

METHODS

Pigs with open, partly obstructed, or completely closed upper airways were transtracheally ventilated either with the Ventrain or by conventional jet ventilation. Airway pressures, haemodynamic parameters, and blood gases obtained in the different settings were compared.

RESULTS

Mean (SD) alveolar minute ventilation as reflected by arterial partial pressure of CO2 was superior with the Ventrain in partly obstructed airways after 6 min in comparison with traditional manual jet ventilation [4.7 (0.19) compared with 7.1 (0.37) kPa], and this was also the case in all simulated airway conditions. At the same time, peak airway pressures were significantly lower and haemodynamic parameters were altered to a lesser extent with the Ventrain.

CONCLUSIONS

The results of this study suggest that the Ventrain device can ensure sufficient oxygenation and ventilation through a small-bore transtracheal catheter when the airway is open, partly obstructed, or completely closed. Minute ventilation and avoidance of high airway pressures were superior in comparison with traditional hand-triggered jet ventilation, particularly in the event of complete upper airway obstruction.