Comparison of Mucosal Pressures Induced by Cuffs of Different Airway Devices

Background: High pressures exerted by balloons and cuffs of conventional endotracheal tubes, the Combitube(R) (Tyco Healthcare Nellcor Mallinckrodt, Pleasanton, CA), the EasyTube(R) (Teleflex Ruesch, Kernen, Germany), the Laryngeal Mask Airway (TM) (LMA North America, San Diego, CA), the Intubating Laryngeal Mask Airway (TM) (Fastrach(R); LMA North America), the ProSeal (TM) (LMA North America), and the Laryngeal Tube (LT; VBM Medizintechnik, Sulz, Germany) may traumatize the pharyngeal mucosa. The aim of this study was to compare pressures exerted on the pharyngeal, tracheal, and esophageal mucosa by different devices designed for securing the patient's airways.

Methods: Nineteen fresh cadavers were included. To measure mucosal pressures, microchip sensors were fixed on the anterior, lateral, and posterior surfaces of the proximal balloon and the distal cuff of the investigated devices. Depending on the respective airway device, the cuff volume was increased in 10-ml increments at the proximal balloon starting from 0 to a maximum of 100 ml, and in 2-ml increments at the distal cuff starting from 0 up to 12 ml.

Results: Tracheal mucosal pressures were significantly higher using the Combitube(R) compared with the endotracheal tube and the EasyTube(R). Maximal esophageal pressures were significantly higher using the EasyTube(R) compared with the Combitube(R). Using cuff volumes according to the manufacturers' guidelines, we found the highest pharyngeal pressures with the Intubating Laryngeal Mask Airway (TM) versus all other devices. At maximal volumes, the Laryngeal Mask Airway (TM), the Intubating Laryngeal Mask Airway (TM), and the ProSeal (TM) induced significantly higher pharyngeal pressures compared with all other devices. Using a pharyngeal cuff volume of 40 ml, the Intubating Laryngeal Mask Airway (TM) followed by the Laryngeal Mask Airway (TM) exerted significantly higher pressures compared with the other devices.     

Comparison of mucosal pressures induced by cuffs of different airway devices

BACKGROUND: High pressures exerted by balloons and cuffs of conventional endotracheal tubes, the Combitube (Tyco Healthcare Nellcor Mallinckrodt, Pleasanton, CA), the EasyTube (Teleflex Ruesch, Kernen, Germany), the Laryngeal Mask Airway (LMA North America, San Diego, CA), the Intubating Laryngeal Mask Airway (Fastrach; LMA North America), the ProSeal (LMA North America), and the Laryngeal Tube (LT; VBM Medizintechnik, Sulz, Germany) may traumatize the pharyngeal mucosa. The aim of this study was to compare pressures exerted on the pharyngeal, tracheal, and esophageal mucosa by different devices designed for securing the patient's airways. METHODS: Nineteen fresh cadavers were included. To measure mucosal pressures, microchip sensors were fixed on the anterior, lateral, and posterior surfaces of the proximal balloon and the distal cuff of the investigated devices. Depending on the respective airway device, the cuff volume was increased in 10-ml increments at the proximal balloon starting from 0 to a maximum of 100 ml, and in 2-ml increments at the distal cuff starting from 0 up to 12 ml. RESULTS: Tracheal mucosal pressures were significantly higher using the Combitube compared with the endotracheal tube and the EasyTube. Maximal esophageal pressures were significantly higher using the EasyTube compared with the Combitube. Using cuff volumes according to the manufacturers' guidelines, we found the highest pharyngeal pressures with the Intubating Laryngeal Mask Airway versus all other devices. At maximal volumes, the Laryngeal Mask Airway, the Intubating Laryngeal Mask Airway, and the ProSeal induced significantly higher pharyngeal pressures compared with all other devices. Using a pharyngeal cuff volume of 40 ml, the Intubating Laryngeal Mask Airway followed by the Laryngeal Mask Airway exerted significantly higher pressures compared with the other devices. CONCLUSIONS: Although some devices exhibit a somewhat higher mucosal pressure when compared with others, the authors believe that the observed differences of the cuff pressures do not suggest a clinically relevant danger, because the investigated devices, except the endotracheal tubes, are not intended for prolonged use.     

An evaluation of the flexiguide introducer with the flexible laryngeal mask airway

Insertion of the flexible Laryngeal Mask Airway has been achieved by a variety of techniques. We have evaluated the Flexiguide for aiding introduction of a flexible Laryngeal Mask Airway in 100 anaesthetised patients. We were successful in establishing a clear airway on the first attempt on 84 (84%) occasions and within two attempts in 97 (97%). The positioning of the laryngeal mask airway was assessed by five measures and was optimally placed in 85% of cases and good in 96%. A clear airway was achieved in 92% of cases. Insertion of the flexible Laryngeal Mask Airway with the Flexiguide was easy in 82 (82%) and slightly difficult in 15 (15%) of cases. Removal of the Flexiguide from the device was easy in 95 (95%) of cases. Airway manoeuvres were used to assist airway placement in 55% of cases with jaw thrust being most common. Minor complications occurred in three (3%) patients: two coughed and one experienced minor tissue trauma during mask insertion. There were no complications associated with use of the Flexiguide during the procedure or after anaesthesia. The Flexiguide is a useful tool to assist insertion of the flexible Laryngeal Mask Airway and is associated with few complications.     

The laryngeal mask simplifies airway management during percutaneous dilational tracheostomy

The Laryngeal Mask Airway (LMA) is used for many procedures which previously required endotracheal intubation. Percutaneous Dilational Tracheostomy (PCT) facilitates the bedside insertion of a tracheostomy tube in the Intensive Care Unit. Most patients requiring this procedure are intubated with a conventional endotracheal tube. Insertion of a LMA has advantages over tracheal intubation for PCT mainly because the artificial airway lies remote from the operating field. Three cases are reported to illustrate these advantages.     

Successful pre-emptive emergency management of a compromised airway with a Proseal™ Laryngeal Mask Airway followed by tracheostomy

Following hemi-glossectomy and right neck dissection a 63-year-old female patient presented as an emergency with a large neck hematoma. There were significant concerns over difficulty in intubation and mask ventilation leading to deterioration into a cannot intubate cannot ventilate (CICV) situation. After careful discussion and planning with the surgical team, who planned a tracheostomy, the situation was salvaged using a ProSealTM Laryngeal Mask Airway (PLMA). The PLMA enabled rapid establishment of a clear airway early in anesthetic induction, controlled ventilation and safe airway maintenance during a difficult tracheostomy.     

Tracheal intubation and alternative airway management devices used by healthcare professionals with different level of pre‐existing skills: a manikin study*

The classic Laryngeal Mask Airway (cLMA^?), ProSeal Laryngeal Mask Airway (PLMA^?), Intubating Laryngeal Mask Airway^? (ILMA^?), Combitube (CT^?), Laryngeal Tube (LT^?) and tracheal intubation (TI) were compared in a manikin study. Nurses, anaesthetic nurses, paramedics, physicians and anaesthetists inserted the devices three times in a randomised sequence. Time taken for successful insertion, success rates and ease of insertion were evaluated. Anaesthetists performed tracheal intubation significantly faster than other healthcare professionals (p < 0.05). Insertion times for the cLMA, PLMA, LT and CT were not significantly different between the groups. Insertion of the CT, ILMA and TI was associated with a significant learning effect in all groups. This was not observed with the cLMA, PLMA or LT. All non‐anaesthetists were able to insert the cLMA, PLMA and LT within two attempts with a > 90% success rate on the first attempt. The ILMA and TI were the only devices where more than one subject experienced some difficulty in insertion. The cLMA, PLMA and LT should be evaluated for use in situations where only limited airway training is possible.     

In vitro study of magnetic resonance imaging artefacts of six supraglottic airway devices

We investigated the artefacts created during magnetic resonance imaging by five different laryngeal mask airways: the Classic (cLMA?); the LMA ProSeal?; the LMA Unique?; the Ambu^® Disposable Laryngeal Mask; the LMA Supreme?; and one other supraglottic airway device, the i‐gel supraglottic airway. The devices were placed on top of and inside a phantom simulator to resemble the position in vivo. The artefacts with the cLMA, Unique and Supreme were similar and related to ferromagnetic material in the pilot balloon valve. Artefacts were more prominent with the ProSeal. There were no artefacts with the Ambu Disposable Laryngeal Mask or the i‐gel.     

Gum elastic bougie-guided insertion of the ProSeal Laryngeal Mask Airway

We tested the hypothesis that gum elastic-bougie-guided insertion of the ProSeal Laryngeal Mask Airway is more frequently successful than introducer tool guided insertion after failed digital insertion. One hundred anaesthetized patients (ASA 1-2, aged 18 to 80 years) were randomized for the second insertion attempt using either the gum elastic bougie-guided or introducer tool techniques. The bougie-guided technique involved priming the drain tube with the bougie, placing the bougie in the oesophagus using laryngoscope guidance, digital insertion along the palato-pharyngeal curve, and bougie removal. The introducer tool technique involved attaching the introducer tool, single-handed rotation along the palatopharyngeal curve, and introducer tool removal. Failed insertion was classified as (i) failed passage into the pharynx, (ii) malposition, or (iii) ineffective ventilation. Any blood staining was documented. Insertion was more frequently successful (50/50 vs 15/50, P=0.0002) and faster (35+/-17 s vs 54+/-45 s, mean+/-SD, P=0.006) with the bougie-guided technique. All failed insertions with the introducer tool technique were successful with the bougie-guided technique. The aetiology of failed insertion was similar for the digital and introducer tool techniques in 94% (33/35) of patients. There was no blood staining on the bougie, laryngoscope or introducer tool at removal, but blood staining was more common on the ProSeal Laryngeal Mask Airway with the introducer tool technique (9/50 vs 2/50, P=0.03). We conclude that the gum elastic bougie-guided insertion has a higher success rate and causes less trauma than the insertion tool insertion technique after failed digital insertion of the ProSeal Laryngeal Mask Airway.     

Haemodynamic and catecholamine stress responses to the Laryngeal Tube-Suction Airway and the Proseal Laryngeal Mask Airway

Supraglottic airway devices such as the ProSeal Laryngeal Mask Airway (PLMA) and Laryngeal Tube-Suction Airway (LTS) that provoke the least stress responses could be beneficial in many situations, especially in patients with cardiovascular disease. We compared the haemodynamic and catecholamine stress response of the LTS and PLMA in a randomised study of 36 patients. Mean arterial pressure, heart rate, epinephrine and norepinephrine levels were all reduced following induction of anaesthesia with no significant differences between the two groups. Following insertion of LTS, mean arterial pressure, heart rate, epinephrine and norepinephrine levels increased to pre-induction levels. However, following the insertion of the PLMA, mean arterial pressure, heart rate, epinephrine and norepinephrine levels remained significantly lower than pre-induction values. Mean arterial pressure, heart rate and epinephrine were significantly greater in the LTS group than in the PLMA group. We conclude that the LTS produces a greater and more sustained haemodynamic and catecholamine stress response than does the PLMA.     

Protein contamination of the Laryngeal Mask Airway and its relationship to re-use

The Laryngeal Mask Airway is a reusable device for maintaining the patency of a patient's airway during general anaesthesia. The device can be reused after it has been cleaned and sterilized. Protein contamination of medical instruments is a concern and has been found to occur despite standard sterilization techniques. The reason for the concern relates to the possibility of the transmission of prions and the risk of developing a neurodegenerative disorder such as Creutzveldt-Jacob disease. The purpose of this study was to quantify the amount of protein contamination that occurs, and to relate this to the number of times the Laryngeal Mask Airway has been used. Fifty previously used Classic Laryngeal Masks were collected after routine sterilization and packaging. The devices were immersed in protein detecting stain and then visual inspection performed to assess the degree and distribution of the staining. The researcher was blinded to the number of times the Laryngeal Mask Airway had been used. Linear regression analysis of the degrees of staining of the airway revealed that protein contamination occurs after the first use of the device and this increases with each subsequent use. This finding highlights the concern that the currently used cleaning and sterilization methods do not prevent the accumulation of proteinaceous material on Laryngeal Mask Airways. Consideration should be given to the search for more efficient cleaning and sterilization techniques or the use of disposable devices.     

Ultrasound-guided percutaneous dilatational tracheostomy with laryngeal mask airway control in a morbidly obese patient

Percutaneous dilatational tracheostomy (PDT) is a widely used and accepted method of long-term ventilation of critically ill patients in many intensive care units. However, it has certain contraindications that must be taken into account; for example, difficult anatomy and short, bull neck that are so often seen in morbidly obese persons. We present a case of a morbidly obese female patient in whom ultrasound-guided PDT was performed and in whom the airway was controlled by Laryngeal Mask Airway (LMA) during the procedure. Possible advantages of an ultrasonography-guided method and LMA control in morbidly obese patients also are discussed.     

A Randomized Controlled Trial Comparing the ProSeal™ Laryngeal Mask Airway with the Laryngeal Tube Suction in Mechanically Ventilated Patients

Background: The ProSeal(TM) Laryngeal Mask Airway (PLMA) (Laryngeal Mask Company, Henley-on-Thames, United Kingdom) is a new laryngeal mask with a modified cuff designed to improve its seal and a drain tube for gastric tube placement. Similarly, the Laryngeal Tube Suction (LTS) (VBM Medizintechnik Gmbh, Sulz a.N, Germany) is a new laryngeal tube that also has an additional channel for gastric tube placement. This study compared the placement and functions of these two devices.

Methods: One hundred fifty patients undergoing general anesthesia for elective surgery were randomly allocated to the PLMA (n = 75) or LTS (n = 75). Oxygenation and ventilation, ease of insertion, fiberoptic view, oropharyngeal leak pressure, ventilatory data, ease of gastric tube insertion, and postoperative airway morbidity were determined.

Results: After successful insertion of the devices in 96% of patients with the PLMA and in 94.4% with the LTS it was possible to maintain oxygenation, ventilation, and respiratory mechanics during the entire duration of surgery. Successful first and second attempt insertion rates were 57 patients (76%) and 15 patients (20%), respectively, for the PLMA and 60 patients (80%) and 11 patients (14.6%), respectively, for the LTS. Airway placement was unsuccessful with the PLMA in three patients and with the LTS in four patients. Time to achieve an effective airway was 36 +/- 24 s with the PLMA versus 34 +/- 25 s with the LTS. Gastric tube insertion was possible in 97.3% of patients with the PLMA and in 96% with the LTS.     

A comparison of the laryngeal tube-S and Proseal laryngeal mask during outpatient surgical procedures

BACKGROUND AND OBJECTIVE: The Laryngeal Tube Sonda (LTS) and the ProSeal Laryngeal Mask Airway (PLMA) are two new devices introduced for maintaining the airway during controlled ventilation under general anaesthesia. The present investigation compared their performance in a randomized controlled study. METHODS: One hundred ASA I-II patients, aged 18-60 yr undergoing elective minor surgery, were randomized to receive either an LTS (n = 50) or PLMA (n = 50) for airway management. After induction of general anaesthesia, the devices were inserted, its correct placement was verified and airway leak pressure was measured. Ease of insertion, quality of airway seal, fibre-optic view and postoperative pharyngeal morbidity were examined. RESULTS: There were no differences in patient characteristics for both groups. First-time and second-time success rates were comparable for both groups (86 vs. 88% and 96 vs. 98% in LTS and PLMA groups, respectively). The airway of one patient in each group could not be managed with these devices after three attempts. Time until delivery of first tidal volume for LTS and PLMA was 24.5 +/- 6.9 and 28.8 +/- 10.3 s. Fixation and manipulation time was 54.9 +/- 15.2 and 73.2 +/- 25 s, respectively (P < 0.05). Airway seal pressure (cm H(2)O) for LTS and PLMA was 20 +/- 8.6 and 24.1 +/- 10.8, respectively (P = 0.04). Patients were questioned on a variety of postoperative pharyngeal morbidities. Only hoarseness was more frequent in the LTS group. CONCLUSIONS: Both devices provide a secure airway, are similar in clinical utility and are easy to insert. Better airway seal was detected in the PLMA group.     

Failed tracheal intubation with the LMA-CTrach in two patients with lingual tonsil hyperplasia

The LMA-CTrach combines the features of the Intubating Laryngeal Mask Airway with a fiberoptic system and a screen for visualization of the airway. Local pathology, such as lingual tonsillar hyperplasia, may obstruct the view of the airway leading to unanticipated difficult intubation. We present two cases of failed intubation with the LMA-CTrach in patients with lingual tonsillar hyperplasia. In both cases, the LMA-CTrach maintained adequate ventilation, giving time to prepare alternative strategies.     

Laryngeal Reflex before and after Placement of Airway Interventions: Endotracheal Tube and Laryngeal Mask Airway™

Background: Previous reports indicate that detrimental laryngeal function persists over several hours after tracheal extubation even in patients who have regained full consciousness from anesthesia. The authors hypothesize that even after minor surgery, the presence of an endotracheal tube (ETT) impairs the receptors at the vocal cord and diminishes the defensive laryngeal function. The hypothesis was tested by comparing types of experimentally induced laryngeal airway reflexes before and after surgery in anesthetized patients with use of either an ETT or a Laryngeal Mask Airway(TM).

Methods: Twenty adult patients undergoing elective minor surgeries were randomly allocated into two groups, the ETT and Laryngeal Mask Airway(TM) groups, depending on the airway management method used during surgery. While maintaining sevoflurane at 1 minimum alveolar concentration, laryngeal and respiratory responses were elicited by instillation of distilled water on the vocal cords immediately before and after surgery. Furthermore, the vocal cord angles were endoscopically measured under complete paralysis.

Results: Some laryngeal reflex responses of both groups, particularly the cough reflex, were significantly attenuated after minor surgery. Significant narrowing of the glottic aperture was evident in patients with ETT placement but not in patients with Laryngeal Mask Airway(TM) placement.     

A randomized controlled trial comparing the ProSeal Laryngeal Mask Airway with the Laryngeal Tube Suction in mechanically ventilated patients

BACKGROUND: The ProSeal Laryngeal Mask Airway (PLMA) (Laryngeal Mask Company, Henley-on-Thames, United Kingdom) is a new laryngeal mask with a modified cuff designed to improve its seal and a drain tube for gastric tube placement. Similarly, the Laryngeal Tube Suction (LTS) (VBM Medizintechnik Gmbh, Sulz a.N, Germany) is a new laryngeal tube that also has an additional channel for gastric tube placement. This study compared the placement and functions of these two devices. METHODS: One hundred fifty patients undergoing general anesthesia for elective surgery were randomly allocated to the PLMA (n = 75) or LTS (n = 75). Oxygenation and ventilation, ease of insertion, fiberoptic view, oropharyngeal leak pressure, ventilatory data, ease of gastric tube insertion, and postoperative airway morbidity were determined. RESULTS: After successful insertion of the devices in 96% of patients with the PLMA and in 94.4% with the LTS it was possible to maintain oxygenation, ventilation, and respiratory mechanics during the entire duration of surgery. Successful first and second attempt insertion rates were 57 patients (76%) and 15 patients (20%), respectively, for the PLMA and 60 patients (80%) and 11 patients (14.6%), respectively, for the LTS. Airway placement was unsuccessful with the PLMA in three patients and with the LTS in four patients. Time to achieve an effective airway was 36 +/- 24 s with the PLMA versus 34 +/- 25 s with the LTS. Gastric tube insertion was possible in 97.3% of patients with the PLMA and in 96% with the LTS. CONCLUSIONS: With respect to both physiologic and clinical function, the PLMA and LTS are similar and either device can be used to establish a safe and effective airway in mechanically ventilated anesthetized adult patients.     

Resistive load of laryngeal mask airway and ProSeal laryngeal mask airway in mechanically ventilated patients

BACKGROUND: The ProSeal Laryngeal Mask Airway (PLMA) ventilation tube is narrower and shorter than the standard Laryngeal Mask Airway (LMA) and is without the vertical bars at the end of the tube. In this randomized, crossover study, PLMA and LMA resistances were compared. METHODS: Respiratory mechanics was calculated in 26 anesthetized, mechanically ventilated patients with both LMA and PLMA. The laryngeal mask positioning was fiberoptically evaluated. Differences in the respiratory mechanics of the LMA and the PLMA were attributed to the differences between the laryngeal masks. RESULTS: In the total study population the airway resistance was 1.5 +/- 2.6 hPa.l-1.s-1 (P = 0.005) higher with the PLMA than with the LMA. During the PLMA use, the peak expiratory flow reduced by 0.02 +/- 0.05 l min-1 (P = 0.046), the expiratory resistance increased by 0.6 +/- 1.3 hPa.l-1.s-1 (P = 0.022), and the time constant of respiratory system lengthened by 0.09 +/- 0.18 s (P = 0.023). These differences doubled when the LMA was better positioned than the PLMA, whereas they disappeared when the PLMA was positioned better than the LMA. CONCLUSIONS: The standard LMA offers a lower resistive load than the PLMA. Moreover, the fitting between the laryngeal masks and the larynx, as fiberoptically evaluated, plays a major role in determining the resistive properties of these devices.     

Laryngeal reflex before and after placement of airway interventions: endotracheal tube and laryngeal mask airway

BACKGROUND: Previous reports indicate that detrimental laryngeal function persists over several hours after tracheal extubation even in patients who have regained full consciousness from anesthesia. The authors hypothesize that even after minor surgery, the presence of an endotracheal tube (ETT) impairs the receptors at the vocal cord and diminishes the defensive laryngeal function. The hypothesis was tested by comparing types of experimentally induced laryngeal airway reflexes before and after surgery in anesthetized patients with use of either an ETT or a Laryngeal Mask Airway. METHODS: Twenty adult patients undergoing elective minor surgeries were randomly allocated into two groups, the ETT and Laryngeal Mask Airway groups, depending on the airway management method used during surgery. While maintaining sevoflurane at 1 minimum alveolar concentration, laryngeal and respiratory responses were elicited by instillation of distilled water on the vocal cords immediately before and after surgery. Furthermore, the vocal cord angles were endoscopically measured under complete paralysis. RESULTS: Some laryngeal reflex responses of both groups, particularly the cough reflex, were significantly attenuated after minor surgery. Significant narrowing of the glottic aperture was evident in patients with ETT placement but not in patients with Laryngeal Mask Airway placement. CONCLUSIONS: With either airway intervention, laryngeal defensive reflexes are depressed immediately after surgery even without visible laryngeal swelling. The sensory impairment attributable to the presence of an ETT cannot be the solo factor responsible for the modification of the defensive airway reflexes elicited from the larynx.     

An evaluation of the Cobra Perilaryngeal Airway: study halted after two cases of pulmonary aspiration

The Cobra Perilaryngeal Airway (Engineered Medical Systems, Indianapolis, IN) is a new supraglottic airway designed for spontaneous and controlled ventilation. It is not yet commercially available in the UK. Our aim was to evaluate the performance of the Cobra Perilaryngeal Airway in a cohort study and in a randomised, controlled, crossover comparison study with the Classic Laryngeal Mask Airway. After studying 29 patients, both studies were suspended and later stopped after two cases of significant pulmonary aspiration had occurred in patients whilst using the Cobra Perilaryngeal Airway. These cases raised concern about both the design and the safety of the Cobra Perilaryngeal Airway, particularly during controlled ventilation. We suggest that the Cobra Perilaryngeal Airway should not be marketed for controlled ventilation until more safety data are available.     

Airway management in a 980-lb patient: use of the Aintree intubation catheter

We report a 22-year-old, 980-lb (445 kg) man with a body mass index of 163 kg/m(2), who needed intubation for tracheotomy surgery, as he was profoundly hypercarbic and reliant on a tight-fitting continuous positive airway pressure mask. Attempts at oral and nasal fiberoptic intubation during topical anesthesia were unsuccessful because of poor patient cooperation and epistaxis. Thus, after awake placement of a size 5 Laryngeal Mask Airway ProSeal LMA; (LMA North America, San Diego, CA), we induced anesthesia using sevoflurane. Then we placed an Aintree stylet (Cook Critical Care, Bloomington, IN) over a fiberoptic bronchoscope, and both were introduced through the LMA into the trachea. We then removed the fiberoptic bronchoscope followed by the LMA. A Parker size 7.5 endotracheal tube was then "railroaded" over the Aintree catheter into the trachea.