Intubating laryngeal mask airway, laryngeal tube, 1100 ml self-inflating bag-alternatives for basic life support?

Impact of laryngeal tube use on chest compression fraction during out-of-hospital cardiac arrest. A prospective alternate month study

AIM

Supraglottic devices are thought to allow efficient ventilation and continuous chest compressions during cardiac arrest. Therefore, the use of supraglottic devices could increase the chest compression fraction (CCF), a critical determinant of patient survival. The aim of this study was to assess the CCF in out-of-hospital cardiac arrest (OHCA) patients ventilated with a supraglottic device.

METHODS

We conducted an open prospective multicenter study with temporal clusters. OHCA patients treated by emergency nurses received either intermittent chest compressions with bag-valve mask ventilations (30:2 rhythm; BVM group); or continuous chest compressions with asynchronous ventilations by laryngeal tube (LT group). The primary endpoint was the CCF assessed using an accelerometer connected to the defibrillator. We also investigated the ease of use of the laryngeal tube.

RESULTS

Eighty-two patients were included (41 in each group); 68% were male and the median age was 68 (54-80) years. Patients and cardiac arrest characteristics did not differ between groups. The CCF was 75% (68-79%) in the LT group and 59% (51-68%) in the BVM group (p<0.01). LT insertion failed in nine out of 40 cases (23%). The median time of LT insertion was 26s (11-56 s). CCF was significantly lower when LT insertion failed (58% (48-74%) vs. 76% (72-80%) when LT insertion succeeded; p=0.01).

CONCLUSION

The use of the LT during OHCA increases the CCF when compared to standard BVM ventilation. However, the impact of LT use on mortality remains unclear.

Influence of airway management strategy on "no-flow-time" during an "advanced life support course" for intensive care nurses - a single rescuer resuscitation manikin study

Background

In 1999, the laryngeal tube (VBM Medizintechnik, Sulz, Germany) was introduced as a new supraglottic airway. It was designed to allow either spontaneous breathing or controlled ventilation during anaesthesia; additionally it may serve as an alternative to endotracheal intubation, or bag-mask ventilation during resuscitation. Several variations of this supraglottic airway exist. In our study, we compared ventilation with the laryngeal tube suction for single use (LTS-D) and a bag-mask device. One of the main points of the revised ERC 2005 guidelines is a low no-flow-time (NFT). The NFT is defined as the time during which no chest compression occurs. Traditionally during the first few minutes of resuscitation NFT is very high. We evaluated the hypothesis that utilization of the LTS-D could reduce the NFT compared to bag-mask ventilation (BMV) during simulated cardiac arrest in a single rescuer manikin study.

Methods

Participants were studied during a one day advanced life support (ALS) course. Two scenarios of arrhythmias requiring defibrillation were simulated in a manikin. One scenario required subjects to establish the airway with a LTS-D; alternatively, the second scenario required them to use BMV. The scenario duration was 430 seconds for the LTS-D scenario, and 420 seconds for the BMV scenario, respectively. Experienced ICU nurses were recruited as study subjects. Participants were randomly assigned to one of the two groups first (LTS-D and BMV) to establish the airway. Endpoints were the total NFT during the scenario, the successful airway management using the respective device, and participants' preference of one of the two strategies for airway management.

Results

Utilization of the LTS-D reduced NFT significantly (p < 0.01). Adherence to the time frame of ERC guidelines was 96% in the LTS-D group versus 30% in the BMV group. Two participants in the LTS-D group required more than one attempt to establish the LTS-D correctly. Once established, ventilation was effective in 100%. In a subjective evaluation all participants preferred the LTS-D over BMV to provide ventilation in a cardiac arrest scenario.

Conclusion

In our manikin study, NFT was reduced significantly when using LTS-D compared to BMV. During cardiac arrest, the LTS-D might be a good alternative to BMV for providing and maintaining a patent airway. For personnel not experienced in endotracheal intubation it seems to be a safe airway device in a manikin use.

New airways for resuscitation?

Over the last 15 years supraglottic airway devices (SADs), most notably the classic laryngeal mask airway (LMA) have revolutionised airway management in anaesthesia. In contrast for resuscitation, both in and outside hospital, facemask ventilation and tracheal intubation remain the mainstays of airway management. However there is evidence that both these techniques have complications and are often poorly performed by inexperienced personnel. Tracheal intubation also has the potential to cause serious harm or death through unrecognised oesophageal intubation. SADs may have a role in airway management for resuscitation as first responder devices, rescue devices or for use during patient extraction. In particular they may be beneficial as the level of skill required to use the device safely may be less than for the tracheal tube. Concerns have been expressed over the ability to ventilate the lungs successfully and also the risk of aspiration with SADs. The only SADs recommended by ILCOR in its current guidance are the classic LMA and combitube. Several SADs have recently been introduced with claims that ventilation and airway protection is improved. This pragmatic review examines recent developments in SAD technology and the relevance of this to the potential for using SADs during resuscitation. In addition to examining research directly related to resuscitation both on bench models and in patients the review also examines evidence from anaesthetic practice. SADS discussed include the classic, intubating and Proseal LMAs, the combitube, the laryngeal tube, laryngeal tube sonda mark I and II and single use laryngeal masks.

Vergleich zwischen Larynxtubus-S und endotrachealer Intubation

BACKGROUND

The value of the laryngeal tube S (LTS) for emergency airway management was evaluated in comparison to endotracheal intubation (ETI).

METHODS

Physicians were asked to perform simulated airway management in an airway mannequin. The physicians were allocated into three groups according to their experience in intubation (1: <50, 2: >50, 3: >500 intubations). The success rate using LTS and ETI, the time needed for securing the airway, and the rating of both techniques by the participants were recorded.

RESULTS

A correct position was achieved with the LTS in 99.39% of attempts (n=325), and with the endotracheal tube in 92.35% (n=302). Using the LTS it took an average time of 10.85 s to achieve the first successful ventilation, as compared to 17.75 s in ETI (p<0.0001). Participants from group 1 needed longer to achieve ETI in the 2nd (18.4 s vs. 16.4 s, p<0.0001) and 3rd attempts (16.9 s vs. 15.8 s, p<0.0001) compared to those from group 3.

CONCLUSIONS

The LTS represents a fast and reliable method to secure the airway and to achieve ventilation in the mannequin model described. The success rate, the time until successful ventilation and the rating by the participants indicates that the LTS is an important alternative to ETI. The LTS offers special benefits for the less experienced users.

Comparison of airway management with the intubating laryngeal mask, laryngeal tube and CobraPLA by paramedical students in anaesthetized patients

BACKGROUND

Because of the importance of airway management in emergency care, alternative methods with shorter learning curves for inexperienced personnel have been looked for as a substitute for endotracheal intubation (ETI).

METHODS

We compared the success of insertion, oxygenation and ventilation of the intubating laryngeal mask (ILMA), laryngeal tube (LT) and CobraPLA (COB) in anaesthetized patients when used by paramedical students. After informed consent, 96 patients were monitored and anaesthetized for general surgery without the use of a muscle relaxant. After the induction of anaesthesia, 32 paramedical students inserted the ILMA, LT or COB in a random order and ventilated the patient for a 60-s period. The number of insertion attempts, the time needed for insertion, and oxygenation and ventilation parameters were recorded. The students gave a subjective evaluation of the airway devices after the test.

RESULTS

Twenty-four of the 32 students (75%) successfully inserted ILMA at the first attempt, compared with 14 of 32 (44%) for LT and seven of 32 (22%) for COB (P<0.001, ILMA vs. COB). One student failed to insert ILMA after all three attempts, compared with seven of 32 (21%) using LT and seven of 32 (21%) using COB (P=not significant). Oxygenation and ventilation parameters did not differ between the groups after successful insertion.

CONCLUSION

Clinically inexperienced paramedical students can successfully use ILMA in anaesthetized patients. Further investigations are warranted to study whether ILMA or LT can replace ETI in emergency airway management when used by inexperienced medical or paramedical staff.

A Comparison of the Laryngeal Tube and Bag-Valve Mask Ventilation by Emergency Medical Technicians: A Feasibility Study in Anesthetized Patients

Airway management is of major importance in emergency care. The basic technique for all health care providers is bag-valve mask (BVM) ventilation, which requires skill and may be difficult to perform. Endotracheal intubation, which is the advanced method for securing the airway, is a demanding technique that has been shown to be associated with infrequent success, even when used by experienced paramedical personnel. Therefore, alternative airway devices have been sought. The use of the laryngeal tube (LT) by experienced anesthesia personnel had been studied in anesthetized patients and manikins in emergency medical training. We decided to evaluate the ability of inexperienced firefighter-emergency medical technician students (fire-EMT) to insert the LT or perform BVM in anesthetized patients. Thirty fire-EMTs randomly inserted the LT (n = 15) and performed 1 min of ventilation or used the BVM (n = 15). We found that all students successfully (100%) inserted the LT. Those who inserted the LT on the first attempt (73%) required 48.2 +/- 14.7 s for the insertion. Both the LT and BVM provided adequate oxygenation and ventilation. In this study, we found that inexperienced fire-EMT students inserted LT and performed 1-min ventilation with a reasonable success rate and insertion time in anesthetized patients.

A comparison of the proseal laryngeal mask airway, the laryngeal tube S and the oesophageal-tracheal combitube during routine surgical procedures

BACKGROUND AND OBJECTIVE

This study was performed to compare three supraglottic airway devices: the ProSeal laryngeal mask airway (PLMA), the laryngeal tube S (LTS) and the oesophageal-tracheal combitube (OTC) during routine surgical procedures.

METHODS

Ninety American Society of Anesthesiologists (ASA) I-III patients scheduled for routine minor obstetric surgery were randomly allocated to the PLMA (n = 30), the LTS (n = 30) or the OTC (n = 30) group, respectively. The overall success rate, insertion time, cuff pressures and resulting airway leak pressures were determined as well as a subjective assessment of handling and the incidence of sore throat, dysphagia and hoarseness were performed.

RESULTS

Insertion time until the first adequate ventilation was significantly (P < 0.0001) shorter in the PLMA (median 29 s; 25-75th percentile 25-48 s; range 10-161 s; success rate 100%) and in the LTS group (38 s; 30-44 s; 13-180 s; 100%) compared to the OTC group (75 s; 48-98 s; 35-180 s; 90%). In vivo cuff pressures and airway leak pressures increased with the inflating cuff volume in all devices and were highest in the OTC group. Postoperatively, patients in the PLMA and the LTS group complained significantly less about sore throat (P < 0.001 and 0.05) and dysphagia (P < 0.001 and 0.02) compared to the OTC group, while there was no difference regarding the incidence of hoarseness. Subjective assessment of handling was comparable with the PLMA and the LTS, but inferior with the OTC.

CONCLUSIONS

In conclusion, both PLMA and LTS proved to be suitable for routine surgical procedures and proved to be superior to the OTC which cannot be recommended for routine use.

Effects of decreasing peak flow rate on stomach inflation during bag-valve-mask ventilation

Reducing inspiratory flow rate and peak airway pressure may be important in order to minimise the risk of stomach inflation when ventilating an unprotected airway with positive pressure ventilation. This study was designed to yield enough power to determine whether employing an inspiratory gas flow limiting bag-valve device (SMART BAG, O-Two Medical Technologies Inc., Ontario, Canada) would also decrease the likelihood of stomach inflation in an established bench model of a simulated unintubated respiratory arrest patient. The bench model consists of a training lung (lung compliance, 50 ml/cm H2O; airway resistance, 4 cm H2O/l/s) and a valve simulating lower oesophageal sphincter opening at a pressure of 19 cm H(2)O. One hundred and ninety-one emergency medicine physicians were requested to ventilate the manikin utilising a standard single-person technique for 1 min (respiratory rate, 12/min; Vt, 500 ml) with both a standard adult bag-valve-mask and the SMART BAG. The volunteers were blinded to the experimental design of the model until completion of the experimental protocol. The SMART BAG versus standard bag-valve-mask resulted in significantly (P < 0.001) lower (mean +/- S.D.) mean airway pressure (14 +/- 2 cm H2O versus 16 +/- 3 cm H2O), respiratory rates (13 +/- 3 breaths per min versus 14 +/- 4 breaths per min), incidence of stomach inflation (4.2% versus 38.7%) and median stomach inflation volumes (351 [range, 18-1211 ml] versus 1426 [20-5882 ml]); lung tidal volumes (538 +/- 97 ml versus 533 +/- 97 ml) were comparable. Inspiratory to expiratory ratios were significantly (P < 0.001) increased (1.7 +/- 0.5 versus 1.5 +/- 0.6). In conclusion, the SMART BAG reduced inspiratory flow, mean airway pressure and both the incidence and actual volume of stomach inflation compared with a standard bag-valve-mask device while maintaining delivered lung tidal volumes and increasing the inspiratory to expiratory ratio.

A comparison of the intubating laryngeal mask airway and the Bonfils intubation fibrescope in patients with predicted difficult airways*

Tracheal intubation with the intubating laryngeal mask airway or the Bonfils intubation fibrescope was performed in 80 patients with predicted difficult airways. Mallampati score, thyromental distance, mouth opening and mobility of the atlanto-occipital joint were used to predict difficult airways. The overall success rate, time to the first adequate lung ventilation and time taken for the successful placement of the tracheal tube were recorded, as well as a subjective assessment of the handling of the device and the incidence of postoperative sore throat and hoarseness. The median [range] time to the first adequate ventilation was significantly shorter with the intubating laryngeal mask airway than with the Bonfils intubation fibrescope (28 [6-85] s vs. 40 [23-77] s, p < 0.005). Tracheal intubation was significantly slower with the intubating laryngeal mask airway than with the Bonfils intubation fibrescope (76 [45-155] s vs. 40 [23-77] s, p < 0.0001. Patients in the Bonfils group suffered less sore throat and hoarseness than those in the other group.

Airway management in cardiac arrest—comparison of the laryngeal tube, tracheal intubation and bag-valve mask ventilation in emergency medical training

Tracheal intubation (ETI) is considered the method of choice for securing the airway and for providing effective ventilation during cardiac arrest. However, ETI requires skills which are difficult to maintain especially if practised infrequently. The laryngeal tube (LT) has been successfully tested and used in anaesthesia and in simulated cardiac arrest in manikins. To compare the initiation and success of ventilation with the LT, ETI and bag-valve mask (BVM) in a cardiac arrest scenario, 60 fire-fighter emergency medical technician (EMT) students formed teams of two rescuers at random and were allocated to use these devices. We found that the teams using the LT were able to initiate ventilation more rapidly than those performing ETI (P < 0.0001). The LT and ETI provided equal minute volumes of ventilation, which was significantly higher than that delivered with the BVM (P < 0.0001). Our data suggest that the LT may enable airway control more rapidly and as effectively as ETI, and compared to BVM, may provide better minute ventilation when used by inexperienced personnel.

The use of modified VBM laryngeal tube compared to Laryngeal Mask Airway during spontaneous ventilation

We have compared the use of the laryngeal mask airway with the new modified laryngeal tube in a prospective randomized controlled study. Sixty ASA 1 or 2 patients, aged 18 to 65 years, scheduled for elective surgery and breathing spontaneously under general anaesthesia, were studied. After preoxygenation, anaesthesia was induced with fentanyl and propofol. The patients were randomized to receive either a laryngeal mask airway or a laryngeal tube. Anaesthesia was maintained with nitrous oxide, oxygen and isoflurane. We recorded the speed and the ease of insertion, the number of attempts needed to successfully secure the airway and intraoperative complications, such as partial airway obstruction needing airway manipulation. The airway devices were removed with the patients fully awake at the end of surgery. Systolic arterial blood pressure, heart rate and end-tidal CO2 were recorded at various time intervals. Postoperative complications were recorded. We found that the incidence of partial airway obstruction needing intraoperative airway manipulation was higher with the laryngeal tube than with the laryngeal mask airway. We conclude that during spontaneous ventilation the modified laryngeal tube is not as reliable in providing a satisfactory airway and we consider it is not a suitable alternative to the laryngeal mask airway.