[Implementation of the laryngeal tube for prehospital airway management: training of 1,069 emergency physicians and paramedics]

[Manikin-based comparison of the use of different supraglottic airways by laypersons]

BACKGROUND

Supraglottic airways (SGA) are an established method of airway management both in prehospital medicine and clinical settings. Endotracheal intubation is the gold standard, but SGA offer advantages in terms of faster application learnability.

OBJECTIVES

In the present study it was investigated whether the time until the first sufficient ventilation in the three examined SGAs applied by bystander differed significantly.

MATERIALS AND METHODS

A total of 160 visitors to a shopping mall were assigned to one of the three SGA after permutative block randomization. The primary endpoint of the present study was the required placement time until the first sufficient ventilation.

RESULTS

Participants managed to place the i‑gel laryngeal mask airway (i-gel, Intersurgical Beatmungsprodukte GmbH, Sankt Augustin, Germany) after a median time of 11 s, whereas the median time until the first sufficient ventilation using a classic laryngeal mask airway (LMA; 26 s) or a laryngeal tube (LT; 28 s) was significantly longer. Thus, the time savings when using the i‑gel compared to the LT and LMA were each significant (p < 0.001), whereas the times between LT and LMA did not differ significantly (p 0.65).

CONCLUSION

The results show that laypersons are able to successfully apply various supraglottic airways to the phantom after a short learning period. The i‑gel laryngeal mask could be placed with the highest success rate and speed.

Impact of the laryngeal tube as supraglottic airway device on blood flow of the internal carotid artery in patients undergoing general anaesthesia

INTRODUCTION

Laryngeal tubes (LT) are supraglottic airway devices routinely used in emergency airway management. During cardiac arrest in a swine model, the carotid artery blood flow is reduced after insertion of a LT. A compression of the internal carotid (ICA) artery by the inflated cuff was shown. Up to now there is no information if the LT has similar effects in humans with possible negative implications for use of the LT in case of cardiac arrest.

OBJECTIVE

We hypothesized that the use of a LT in humans significantly reduces the blood flow in the ICA compared facemask ventilation. A significant reduction was defined as a 25% reduction from baseline values.

MATERIAL AND METHODS

After induction of general anaesthesia and reaching a haemodynamic steady state (stable heart rate >50/min and mean arterial pressure >60 mmHg), blood flow within the ICA was measured via doppler sonography during pressure-controlled ventilation with facemask-, laryngeal tube- and laryngeal mask.

RESULTS

We found no differences in the carotid blood flow. Neither between the facemask ventilation (right side 419 ± 159 ml min^-1, left side 355 ± 120 ml min^-1) and the laryngeal tube ventilation (right side 400 ± 131 ml min^-1, left side 384 ± 124 ml min^-1. p = 0.86 and p = 0.12), nor the facemask-ventilation and the laryngeal mask ventilation (right ICA 415 ± 150 ml min^-1, left ICA 485 ± 274 ml min^-1, p = 0.49 and 0.26).

CONCLUSIONS

In humans the LT does not impair blood flow of the internal carotid artery during ventilation in general anaesthesia. Further studies are needed to confirm our findings under the conditions of cardiac arrest.

Airway management techniques in a restricted-access situation: a manikin study

BACKGROUND

Access to patients can be restricted in emergency situations. A variety of techniques and devices are available for use in patients who require oxygenation in a restricted-access situation.

OBJECTIVES

The aim of this study was to investigate whether there is one ventilation technique that is superior to others.

MATERIALS AND METHODS

Fifty-four emergency medical services providers including emergency medical technicians, paramedics and physicians were asked to use a bag-valve mask (BVM), a laryngeal mask airway (LMA), and a laryngeal tube (LT) to ventilate a full-scale manikin sitting upright in the driver's seat of a motor vehicle. Access to the manikin was gained through the side window and from the backseat.

RESULTS

There were significant differences in time to first successful ventilation between the two approaches for access to the airway. The fastest median time to ventilation was obtained with the BVM (7 and 8 s), followed by the LT (13 and 14 s) and the LMA (15 s for both types of access). Overall success rates were 97.2% for the BVM, 96.3% for the LMA, and 100% for the LT. Most participants needed two attempts for each device. There were no significant differences between participants depending on the level of qualification or professional experience. The BVM was rated the lowest and the LT was rated the highest for ease of use.

CONCLUSION

Supraglottic airway devices appear to offer advantages in restricted-access situations.

Laryngeal tube suction for airway management during in-hospital emergencies

OBJECTIVE:

The role of supraglottic airway devices in emergency airway management is highlighted in international airway management guidelines. We evaluated the application of the new generation laryngeal tube suction (LTS-II/LTS-D) in the management of in-hospital unexpected difficult airway and cardiopulmonary resuscitation.

METHODS:

During a seven-year period, patients treated with a laryngeal tube who received routine anesthesia and had an unexpected difficult airway (Cormack Lehane Grade 3-4), who underwent cardiopulmonary resuscitation, or who underwent cardiopulmonary resuscitation outside the operating room and had a difficult airway were evaluated. Successful placement of the LTS II/LTS-D, sufficient ventilation, time to placement, number of placement attempts, stomach content, peripheral oxygen saturation/end-tidal carbon dioxide development (SpO2/etCO2) over 5 minutes, subjective overall assessment and complications were recorded.

RESULTS:

In total, 106 adult patients were treated using an LTS-II/LTS-D. The main indication for placement was a difficult airway (75%, n=80), followed by cardiopulmonary resuscitation (25%, n=26) or an overlap between both (18%, n=19). In 94% of patients (n=100), users placed the laryngeal tube during the first attempt. In 93% of patients (n=98), the tube was placed within 30 seconds. A significant increase in SpO2 from 97% (0-100) to 99% (5-100) was observed in the whole population and in cardiopulmonary resuscitation patients. The average initial etCO2 of 39.5 mmHg (0-100 mmHg) decreased significantly to an average of 38.4 mmHg (10-62 mmHg) after 5 minutes. A comparison of cardiopulmonary resuscitation patients with non-cardiopulmonary resuscitation patients regarding gastric contents showed no significant difference.

CONCLUSIONS:

LTS-D/LTS-II use for in-hospital unexpected difficult airway management provides a secure method for primary airway management until other options such as video laryngoscopy or fiber optic intubation become available.

The laryngeal tube - a helpful tool for cardiopulmonary resuscitation in the dental office?

BACKGROUND

Supraglottic airway adjuncts such as the laryngeal tube (LT) have been recommended to be used by cardiopulmonary resuscitation (CPR) first responders.Objective This study aims to evaluate the performance characteristics of dental students and dentists using the LT in comparison to a conventional bag valve mask device (BVM) within manikin CPR training.

METHOD

A group of eight dentists and 12 dental students performed randomised crossover CPR training using LT and BVM. Time intervals needed to perform five CPR cycles were recorded, as well as tidal and total gastric inflation volumes.

RESULTS

Median tidal volumes 0-1025 ml (median 462.5 ml) were observed using BVM and 100-500 ml (median 237.5 ml) with LT (p = 0.02). Total gastric inflation of 0-2900 ml was measured using BVM, no gastric inflation using LT (p = 0.0005). Time intervals needed to perform five CPR cycles did not differ between BVM (range 87.5-354.5 s, median 112 s) and LT (range 84.7-322.3 s, median 114 s) (p = 0.55). A median delay of 37.6 s (range 0-82.1 s) before starting CPR was observed using LT.

CONCLUSIONS

Lower tidal volumes but also lower or even no gastric inflation may be observed when dentists use a laryngeal tube during CPR. Respective training must focus on chest compressions. These must be started before inserting the LT or a different supraglottic airway adjunct and be delivered continuously during insertion. It is recommended to use a supraglottic airway such as an LT only after having been trained in its use.

Insertion Success of the Laryngeal Tube in Emergency Airway Management

Background. Emergency airway management (AM) is a priority when resuscitating critically ill or severely injured patients. The goal of this study was to determine the success rates of LT insertion during AM. Methods. Studies that included LT first-pass insertion (FPI) and overall-pass insertion (OPI) success by emergency medical services and in-hospital providers performing AM for emergency situations as well as for scheduled surgery published until July 2014 were searched systematically in Medline. Results. Data of 36 studies (n = 1,897) reported a LT FPI success by physicians of 82.5% with an OPI success of 93.6% (p < 0.001). A cumulative analysis of all 53 studies (n = 3,600) led to FPI and OPI success of 80.1% and 92.6% (p < 0.001), respectively. The results of 26 studies (n = 2,159) comparing the LT with the laryngeal mask airway (LMA) demonstrated a FPI success of 77.0 versus 78.7% (p = 0.36) and an OPI success of 92.2 versus 97.7% (p < 0.001). Conclusion. LT insertion failed in the first attempt in one out of five patients, with an overall failure rate in one out of 14 patients. When compared with the LT, the LMA had a cumulative 5.5% better OPI success rate.

Difficult intubation and outcome after out-of-hospital cardiac arrest: a registry-based analysis

Background

Airway management during resuscitation attempts is pivotal for treating hypoxia, and endotracheal intubation is the standard procedure. This German Resuscitation Registry analysis investigates the influence of airway management on primary outcomes after out-of-hospital cardiac arrest, in a physician-based emergency system.

Methods

A total of 8512 patients recorded in the German Resuscitation Registry (2007–2011) were analyzed. The Return of Spontaneous Circulation After Cardiac Arrest (RACA) score was used to compare observed return of spontaneous circulation (ROSC) rates with the ROSC predicted by the score and to analyze factors influencing the primary outcome. Patients were classified into three groups: difficult intubation, impossible intubation, and a control group with normal airways.

Results

The observed ROSC matched the predicted ROSC in the group with difficult airways. The impossible intubation group had lower ROSC rates (31.3 % vs. 40.5 %; P < 0.05). Impossible intubation was more frequent in men (OR 2.28; 95 % CI, 1.43–3.63; P = 0.001), young patients (OR 2.18; 95 % CI, 1.26–3.76; P = 0.005) and those with trauma (OR 2.22; 95 % CI, 1.01–4.85; P = 0.046). Fewer impossible intubations were reported when the emergency physicians were anesthesiologists (OR 0.65; 95 % CI, 0.44–0.96; P = 0.028). If a supraglottic airway device was not used in the impossible intubation group, the observed ROSC (18.0 %; 95 % CI, 7.4–28.6 %) was poorer than predicted (38.2 %) (P < 0.05).

Conclusions

Outcomes after resuscitation attempts are poorer when endotracheal intubation is not possible. Predictive factors for impossible intubation are male gender, younger age, and trauma. Supraglottic airway devices should be used at an early stage whenever these negative factors are present.

Electronic supplementary material

The online version of this article (doi:10.1186/s13049-015-0124-0) contains supplementary material, which is available to authorized users.

Complications associated with the prehospital use of laryngeal tubes--a systematic analysis of risk factors and strategies for prevention

OBJECTIVE

With the increasing spread of laryngeal tubes (LT) in emergency medicine, complications and side-effects are observed. We sought to identify complications associated with the use of LTs in emergency medicine, and to develop strategies to prevent these incidents.

METHODS

In a prospective clinical study, all patients who had their airways managed in the field with a LT and who were admitted through the emergency department of the Frankfurt University Hospital during a 6 year period were evaluated using anonymised data collection sheets. A team of experts was available 24/7 and was requested whenever a patient was admitted with a LT in place. This team evaluated the condition of the patients with respect to prehospital airway management and was responsible for further advanced airway management. All complications were analysed, and strategies for prevention developed.

RESULTS

One hundred eighty nine patients were included and analysed. The initial cuff pressure of the LTs was 10 0 cm H₂O on the median. Complications consisted of significant tongue swelling (n=73; 38.6%), resulting in life-threatening cannot ventilate, cannot intubate scenarios in two patients (1.0%) and the need for surgical tracheostomy in another patient, massive distension of the stomach (n=20, 10.6%) with ventilation difficulties when LTs without gastric drainage were used; malposition of the LT in the piriform sinus (n=1, 0.5%) and significant bleeding from soft tissue injuries (n=4, 2.1%).

CONCLUSIONS

The prehospital use of LTs may result in severe and even life-threatening complications. Likely, such complications could have been prevented by using gastric drainage and cuff pressure adjustment. Both, prehospital health care providers and emergency department staff should develop a greater awareness of such complications to best avoid them in the future.

[Taking over a patient with preclinical laryngeal tube]

Endotracheal intubation (ETI) is the most effective method for securing the airway. However, the practice and theory of ETI differ considerably. There is a wide gap between reality and the optimum of quality and quantity required by many specialist organizations, e.g., the European Resuscitation Council. Alternative airway devices, such as a laryngeal tube, can be useful provided the hospital staff know how the device functions and how to avoid or control complications.

Laryngeal tube use in out-of-hospital cardiac arrest by paramedics in Norway

Background

Although there are numerous supraglottic airway alternatives to endotracheal intubation, it remains unclear which airway technique is optimal for use in prehospital cardiac arrests. We evaluated the use of the laryngeal tube (LT) as an airway management tool among adult out-of-hospital cardiac arrest (OHCA) patients treated by our ambulance services in the Haukeland and Innlandet hospital districts.

Methods

Post-resuscitation forms and data concerning airway management in 347 adult OHCA victims were retrospectively assessed with regard to LT insertion success rates, ease and speed of insertion and insertion-related problems.

Results

A total of 402 insertions were performed on 347 OHCA patients. Overall, LT insertion was successful in 85.3% of the patients, with a 74.4% first-attempt success rate. In the minority of patients (n = 46, 13.3%), the LT insertion time exceeded 30 seconds. Insertion-related problems were recorded in 52.7% of the patients. Lack of respiratory sounds on auscultation (n = 100, 28.8%), problematic initial tube positioning (n = 85, 24.5%), air leakage (n = 61, 17.6%), vomitus/aspiration (n = 44, 12.7%), and tube dislocation (n = 17, 4.9%) were the most common problems reported. Insertion difficulty was graded and documented for 95.4% of the patients, with the majority of insertions assessed as being “Easy” (62.5%) or “Intermediate” (24.8%). Only 8.1% of the insertions were considered to be “Difficult”.

Conclusions

We found a high number of insertion related problems, indicating that supraglottic airway devices offering promising results in manikin studies may be less reliable in real-life resuscitations. Still, we consider the laryngeal tube to be an important alternative for airway management in prehospital cardiac arrest victims.

[Comparison of ready-to-use devices for emergency cricothyrotomy : randomized and controlled feasibility study on a mannequin]

BACKGROUND

According to various algorithms of airway management, emergency cricothyrotomy (coniotomy) represents the ultimate step for managing the difficult airway. As most physicians have limited experience with this technique several ready-to-use devices have emerged on the market with the aim of simplifying the procedure. However, they differ in details, such as configuration or the order of particular steps. Therefore, the intention of this randomized and controlled feasibility study was to test various sets and compare them to the classical surgical approach.

METHODS

After obtaining informed consent German anesthesiologists who were also board-certified emergency physicians were asked to perform the cricothyrotomy procedure in a cervical mannequin (Frova Crico-Trainer, VBM Medizintechnik) in a randomized order using a scalpel, peripheral intravenous cannula and the commercial devices TracheoQuick, Airfree, Portex-Crico-Kit, Quicktrach I and Quicktrach II. Handling and duration of the procedures were analyzed utilizing the Wilcoxon signed-rank test. A p-value  < 0.05 was considered significant.

RESULTS

A total of 20 anesthesiologists (11 residents and 9 specialists) with a mean age of 34 years were included in this study and all had the additional qualification of emergency physician, which enabled them to work in prehospital emergency medicine in Germany. Participants had been working in this field for an average of 29.9 months (range 6-84 months) performing a mean of 1.9 24 h shifts per month (range 1-6 shifts/month). Of the participants only 2 (10%) had performed a coniotomy in reality before. In this study surgical coniotomy required a median time of 35.4 s (range 30.0-61.8 s). No significant differences were seen when the cuffed devices Quicktrach II (median: 29.9 s, range 25.0-50.5 s) and Portex-Crico-Kit (median: 46.7 s, range 37.0-67.3 s) were used. A significantly faster airway was established using the non-cuffed devices TracheoQuick (median: 20.2 s, range 11.4-44.7 s), Airfree (median: 22.8 s, range 14.3-33.2 s), Quicktrach I (median: 21.1 s, range 14.5-32.4 s) and the peripheral intravenous cannula (median: 19.2 s, range 10.8-27.8 s). Incorrect tube placements were not observed.

CONCLUSION

This study allowed the comparison of surgical coniotomy to several ready-to-use devices in a standardized setting utilizing a reusable plastic mannequin. The interpretation for real emergency conditions is limited as individual anatomy, traumatic alterations of the neck or complications, such as bleeding or damage of important structures were not part of the study objectives. However, all participating emergency physicians successfully used the coniotomy sets provided at the first attempt. No device required significantly more time than the surgical approach. The procedures using cuffed devices lasted longer in comparison to procedures using uncuffed ones; however, this difference would only play a minor role in reality as effective ventilation with minute volumes greater than 7 l/min will only be achieved by a cuffed cannula with a minimum internal diameter of 4 mm. Devices with no cuff or with tube diameters smaller than 4 mm will only allow oxygenation of the patient, which in turn requires an inspiratory oxygen concentration of 100% and a relatively high ventilation frequency.