Pharyngeal mucosal pressures with the laryngeal tube airway versus ProSeal laryngeal mask airway

We tested the hypothesis that mucosal pressures are higher for the laryngeal tube airway trade mark than the ProSeal laryngeal mask airway. Fifteen fresh cadavers were studied. Microchip pressure sensors were attached to the laryngeal tube airway and ProSeal laryngeal mask airway at four similar anatomical locations (base of tongue, lateral pharynx, posterior pharynx and posterior hypopharynx) and three dissimilar locations (laryngeal tube airway trade mark, anterior and lateral hypopharynx; ProSeal laryngeal mask airway, pyriform fossa). The cuff volume (laryngeal tube airway, < or = 140 ml; ProSeal laryngeal mask airway, < or = 30 ml) was adjusted until the oropharyngeal leak pressure was 15 cm H2O and the mucosal pressures recorded. This was repeated at an oropharyngeal leak pressure of 20, 25 and 30 cm H2O. Mucosal pressures in the lateral pharynx were always similar. Mucosal pressures at the base of tongue and posterior pharynx were similar for the laryngeal tube airway and ProSeal laryngeal mask airway at 15 and 20 cm H2O, but were higher for the laryngeal tube airway at 25 cm H2O at 30 cm H2O. Mucosal pressures in the posterior hypopharynx were always higher for the laryngeal tube airway (all: p < 0.03). Mean mucosal pressures for the laryngeal tube airway ranged from 8-31, 2-13 and 15-41 cm H2O for the base of tongue, lateral pharynx and posterior pharynx (proximal cuff) respectively and 3-7, 3-7 and 7-18 cm H2O for the anterior, lateral and posterior hypopharynx (distal cuff) respectively. Mean mucosal pressures for the ProSeal laryngeal mask airway ranged from 6-23, 3-10, 8-25, 6-17 and 2-8 cm H2O for the base of tongue, lateral pharynx, posterior pharynx, pyriform fossa and posterior hypopharynx respectively. We conclude that mucosal pressures are higher for the laryngeal tube airway, particularly when oropharyngeal leak pressure greater than 25 cm H2O. This suggests that mucosal ischemic injury will be more common with the LTA than the PLMA.     

Esophageal aspiration of air through the drain tube of the ProSeal laryngeal mask.

IMPLICATIONS: Two patients experienced partial upper airway obstruction while breathing spontaneously with the ProSeal laryngeal mask airway. This resulted in esophageal aspiration of air through the drain tube.     

ProSeal laryngeal mask airway for cardiac surgery after airway rescue

We present the case of the successful use of a ProSeal laryngeal mask airway in a severe obese 41-year-old women with a difficult airway, scheduled to undergo cardiac surgery (off-pump coronary artery bypass). Two intubation attempts failed and face mask ventilation became impossible with rapidly falling peripheral oxygen saturation. A ProSeal laryngeal airway was railroaded over a tracheal tube guide, a gastric tube was inserted along the drain tube and the patient underwent positive pressure ventilation, resulting in normal gas exchange and an oropharyngeal leak pressure > 40 cm H2O. The decision was taken to proceed with the ProSeal as the airway during the surgical intervention. Surgery was uneventful and the ProSeal was removed on the ICU three hours later. This case reports illustrates the successful use of a guided insertion of the ProSeal laryngeal mask for airway rescue in cardiac surgery.     

Comparison of the standard laryngeal mask airway and the ProSeal laryngeal mask airway in obese patients

Background. The ProSeal^TM laryngeal mask airway (PLMA) may haveadvantages over the laryngeal mask airway (LMA     

The ProSeal laryngeal mask airway and the laryngeal tube Suction for ventilation in gynaecological patients undergoing laparoscopic surgery

BACKGROUND AND OBJECTIVE: ProSeal Laryngeal Mask Airway (PLMA) and Laryngeal Tube Suction (LTS), supraglottic airway devices allowing gastric drainage, were compared in this prospective, randomized study for airway management under conditions with elevated intra-abdominal pressure induced by capnoperitoneum. METHODS: Fifty patients undergoing elective gynaecological laparoscopic surgery were randomized to two groups of 25 each. After induction of general anaesthesia, devices were inserted, correct placement was verified, airway leak pressure was measured, and a gastric tube was inserted. Ease of insertion, quality of airway seal, risk of gastric insufflation and patient comfort were investigated. RESULTS: There were no differences in patient characteristics data for both groups. First-time insertion success rates were comparable for both groups: 92%--first attempt, 8%--second attempt for PLMA and LTS. Time until delivery of the first tidal volume for PLMA and LTS was 23.2 +/- 6.1 and 23.5 +/- 6.6s, airway leak pressure was 45.4 +/- 4.9 cmH2O and 45.6 +/- 6.7 cmH2O with cuff pressures adjusted to 60 cmH2O. No gastric insufflation, gas loss or signs of regurgitation were detected. Placement of a gastric tube was successful in all patients. Patients were questioned for sore throat and dysphagia after removal of devices. Sore throat was stated in 1%/0% (PLMA) and 8%/4% (LTS) after 6/24 h, dysphagia in 4%/4% (PLMA) and 12%/4% (LTS). CONCLUSIONS: Both devices provide a secure airway even under conditions of elevated intra-abdominal pressure. In this pilot study, no differences concerning handling or quality of airway seal were detected between PLMA and LTS.     

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.     

Maximum minute ventilation test for the ProSeal laryngeal mask airway

One of the distinguishing features of the ProSeal laryngeal mask airway (PLMA) is that it can cause upper airway obstruction, even when it is correctly inserted behind the cricoid cartilage. We used a hyperventilation test, the maximum minute ventilation test (MMV test), to aid in the diagnosis of upper airway obstruction after PLMA insertion. The patient was briefly hyperventilated for 15 s yielding a MMV value equal to 4 x (breaths/15 s) x (exhaled tidal volume). MMV values were collected in 317 adult women and men over 6 mo. Critical MMV values were obtained in 17 of 317 patients, 15 of 317 (4.7%) of which were due to insertion of the PLMA. The PLMA was removed in seven of 317 (2.2%) patients. The most common cause of upper airway obstruction due to the PLMA was laryngeal obstruction. This refers to compression of supraglottic and glottic structures with resulting narrowing and compromise of the airway. A second, much less common, form of airway obstruction was bilateral cuff infolding with or without downfolding of the epiglottis. Finally, we discuss the margin of safety for minute ventilation, defined as the excess of the MMV over and above basal minute ventilation requirements for the patient. With critical MMV, the margin of safety is drastically reduced or nonexistent. IMPLICATIONS: One of the distinguishing features of the ProSeal laryngeal mask airway (PLMA) is that it can cause upper airway obstruction, even when it is correctly inserted behind the cricoid cartilage. We used a hyperventilation test, the maximum minute ventilation test, to aid in the diagnosis of upper airway obstruction after PLMA insertion.     

The effects of head flexion on airway seal, quality of ventilation and orogastric tube placement using the ProSeal laryngeal mask airway

This prospective self-controlled study was designed to evaluate the influences of head flexion on airway seal, quality of ventilation, and orogastric tube placement through the ProSeal laryngeal mask airway (ProSeal LMA) in 80 anaesthetised, paralysed adult patients. After the ProSeal LMA was inserted and the cuff pressure was set at 5.9 kPa, ventilation quality, airway seal pressure, fibreoptic positions of the cuff and the drainage tube, orogastric tube placement and efficacy of intermittent positive pressure ventilation (IPPV) were assessed in two randomly selected positions: neutral and flexed position. When compared to the neutral head position, the head flexed significantly improved the airway seal pressure and the quality of ventilation of the ProSeal LMA (p < 0.05). Fibreoptic scores of the cuff position did not correlate with either the ability to obtain excellent or adequate ventilation through the ProSeal LMA or the ability to generate an airway seal pressure of >or= 2 kPa. Orogastric tube placement via the drainage tube was successful on the first attempt in all patients in the neutral position compared with seven failures following three attempts in the flexed position (p < 0.05). There were no significant differences between the two head positions in the volume of air required to obtain an intracuff pressure of 5.9 kPa, fibreoptic score of the drainage tube position, and expiratory tidal volume and peak inspiratory pressure during IPPV (p > 0.05). In conclusion, head flexion improves airway seal and ventilation quality of the ProSeal LMA. However, placement of an orogastric tube via the drainage tube is impaired in the flexed position compared to the neutral position. Fibreoptic scoring of the ProSeal cuff position is not an accurate test to assess the airway seal and ventilation function.