LMA ProSealTM Research Articles

Long Lasting Surgery Performed Under Regional Anaesthesia, Total Intravenous Anaesthesia and Prosealtm Laryngeal Mask Airway: A Series of Case Reports

Long Lasting Surgery Performed Under Regional Anaesthesia, Total Intravenous Anaesthesia and Prosealtm Laryngeal Mask Airway: A Series of Case Reports

125. Long Lasting Surgery Performed Under Regional Anaesthesia, Total Intravenous Anaesthesia and Prosealtm Laryngeal Mask Airway: A Series of Case Reports

125. Long Lasting Surgery Performed Under Regional Anaesthesia, Total Intravenous Anaesthesia and Prosealtm Laryngeal Mask Airway: A Series of Case Reports

This Month in Anesthesiology

The change from earth's anoxic to oxic atmosphere in relation to the development of life is discussed. See the accompanying Editorial View on page 1 Total intravenous anesthesia was not associated with improved neurologic outcome in traumatic brain injury.Orally administered cannabis extract did not show analgesic efficacy.The need for large randomized trials to determine whether treatment strategies aimed at glucose control will improve patient outcomes is reviewed. See the accompanying Editorial View on page 1 1 Obesity is a major cause of type 2 diabetes, clinically evidenced as hyperglycemia. The altered glucose homeostasis is caused by faulty signal transduction via the insulin signaling proteins which results in decreased glucose uptake by the muscle, altered lipogenesis, and increased glucose output by the liver. The etiology of this derangement in insulin signaling is related to a chronic inflammatory state, which modifies the insulin signaling proteins' functions. There are substantial differences in the molecular mechanisms of insulin resistance among different organs. Multipronged therapies aimed at rectifying obesity-induced anomalies in the central nervous system and peripheral tissues may be beneficial in obesity-induced insulin resistance.The Laryngeal Tube Suction II (LTSII) is a recent revision of the Laryngeal Tube Suction. This study compared insertion and ventilation profiles of LTSII and ProSeal ™ Laryngeal Mask Airway (PLMA™) in anesthetized patients. The rate of successful insertion, insertion time, airway leak pressure, tidal volume, and postoperative airway morbidity were among many parameters measured. Insertion was successful in 37 and 48 of 50 patients with LTSII and PLMA™, respectively. The PLMA™ was superior to the LTSII in most measures of ventilation performance. Airway management with LTSII is inferior to that with PLMA™.In this editorial, Hogan reviews and comments on the implications of a pharmacogenomics study of nitrous oxide by Nagele et al. In Nagele et al. 's study, patients with a certain genetic mutation develop higher plasma homocysteine levels after nitrous oxide anesthesia than normal patients. The study suggests that deleterious events after nitrous oxide exposure may be enriched in a subset of patients with certain genetic predisposition. Hogan states that trials of nitrous oxide exposure in the clinical setting will be substantially strengthened by inclusion of single-carbon genotyping. Furthermore, knowing in advance who can breathe nitrous oxide without fear of clinically relevant hyperhomocysteinemia may help to sustain its safe use in the future.Recent investigations have focused on increased operating room (OR) throughput without increasing total OR time. The authors examined if a system of parallel processing for lower extremity joint arthroplasties sustainably reduces nonoperative time and increases throughput. The high-throughput parallel processing strategy included neuraxial anesthesia, an induction room, patient selection, an additional circulating nurse, and specific end-of-case transfer to recovery. Throughput increased from 2.6 to 3.4 arthroplasties per day per room. Both nonoperative time and operative time decreased. Because joint arthroplasties generated a positive margin greater than the incremental cost, the high-throughput system improved financial performance. See the accompanying Editorial View on page 3

Protection Against Large-volume Regurgitated Fluid Aspiration by the ProSeal™ Laryngeal Mask Airway

The ProSeal laryngeal mask airway (PLMA) is designed to protect the airway from regurgitated fluid. However, successful channeling of large volumes of regurgitated fluid by PLMA is rarely reported. This case report states that a large volume of regurgitated fluid was successfully channeled by a PLMA. The patient was a healthy 43-year-old male, properly fasted, undergoing transurethral cystolithotomy under general anesthesia with a correctly-placed PLMA. Unexpectedly, a large volume of regurgitated fluid (> 500 mL) spurted out from the PLMA esophageal drainage tube 2 hours after surgery. Careful gastric decompression was performed and airway toilet showed no evidence of aspiration of gastric contents. An endotracheal tube was then placed in lieu of the PLMA for airway maintenance. By the end of surgery, 1300 mL of fluid was drained through the gastric tube. Extubation was smooth and the patient had an uneventful recovery. Further radiological examination revealed the existence of an unrecognized vesicorectal fistula, which allowed the cystoscopic irrigation fluid to escape to the GI tract, resulting in massive gastric regurgitation. The patient underwent fistula repair a week later and was discharged without further difficulty. This is a unique clinical case report to show PLMA can be effective in preventing aspiration when massive passive regurgitation occurs. Strategies in the management of massive regurgitation during PLMA use are discussed.

Brief review: The Cobra Perilaryngeal Airway (CobraPLA®) and the Streamlined Liner of Pharyngeal Airway (SLIPA™) supraglottic airways

To summarize the published literature related to two, new supraglottic airways (SGAs): the Cobra Perilaryngeal Airway (CobraPLA) and the Streamlined Liner of Pharyngeal Airway (SLIPA). We identified original articles, through searches on Medline and PubMed, using the keywords 'Cobra', 'CobraPLA', 'Cobra-PLA', 'PLA', and 'SLIPA'. Searches identified 28 publications evaluating the CobraPLA, six of which were randomized, controlled trials. Five publications evaluated the SLIPA, two of which were randomized, controlled trials. Studies compared the CobraPLA with a number of SGAs, in regards to both efficacy and safety. While the CobraPLA is comparable to the laryngeal mask airway (LMA) Classic, with respect to insertion times and the incidence and severity of sore throat, the CobraPLA is superior, with respect to airway sealing pressure, and has been used successfully in patients with limited mouth opening and limited head extension. Insertion times, first insertion success rates, recovery times, and hemodynamic responses, associated with insertion of the SLIPA, are similar to those of the LMA Proseal. Although the SLIPA has a unique reservoir chamber to contain regurgitated fluid, the extent of its protection against pulmonary aspiration has not been established in the clinical setting. Both the CobraPLA and the SLIPA are intended for use during short procedures under general anesthesia, and have comparable efficacy and complication rates in comparison to the LMA Classic. Both airways may be considered as primary SGA devices, and the CobraPLA may be also be used as a rescue airway device.

A Comparison of Seal in Seven Supraglottic Airway Devices Using a Cadaver Model of Elevated Esophageal Pressure

Supraglottic airway devices are increasingly important in clinical anesthesia and prehospital emergency medicine, but there are only few data to assess the risk for aspiration. We designed this study to compare the seal of seven supraglottic airway devices in a cadaver model of elevated esophageal pressure. The classic laryngeal mask airway, laryngeal mask airway ProSeal, intubating laryngeal mask airway Fastrach, laryngeal tube, laryngeal tube LTS II, Combitube, and Easytube were inserted into unfixed human cadavers with an exposed esophagus that had been connected to a water column of 130 cm height. Slow and fast increases of esophageal pressure were performed and the water pressure at which leakage appeared was registered. The Combitube, Easytube, and intubating laryngeal mask Fastrach withstood the water pressure up to more than 120 cm H2O. The laryngeal mask airway ProSeal, laryngeal tube, and laryngeal tube LTS II were able to block the esophagus until 72-82 cm H2O. The classic laryngeal mask airway showed leakage at 48 cm H2O, but only minor leakage was found in the trachea. Devices with an additional esophageal drain tube drained fluid sufficiently without pulmonary aspiration. Concerning the risk of aspiration, the use of devices with an additional esophageal drainage lumen might be superior for use in patients with an increased risk of aspiration. The Combitube, Easytube, and intubating laryngeal mask Fastrach showed the best capacity to withstand an increase of esophageal pressure.

The effect of ultrasonic cleaning on the elimination of postoperative residual protein from the proseal™ laryngeal mask airway

Background: Reusable ProsealTM laryngeal mask airways (PLMAs) can act as a vector for the transmission of prion diseases such as variant Creutzfeldt-Jacob disease. This study tested the hypothesis that supplementary ultrasonic cleaning facilitates the removal of protein deposits on PLMAs after anesthesia. Methods: After clinical use, 40 PLMAs were randomly allocated into two groups. In the first group, the PLMAs were washed by hand and were then subsequently placed in an autoclave at 134oC for 40 min (Group 1, n = 20). In the second group, the PLMAs were washed by hand and ultrasonic cleaning using an enzymatic solution for 5 min, and were then subsequently placed in an autoclave (Group 2, n = 20). In both groups, protein deposits were detected on PLMAs by erythrosin staining. A staining score designated as none (0%), mild (0−20%), moderate (20−80%) and severe (80−100%), was assigned to each site (outer surface, inner surface and edges of the cuff, airway and drain tube, finger strap) according to the percentage of the stained surface area. Results: Despite the cleaning of the masks, residual protein was found on the outer surface, inner surface and edge of the cuff, airway and drain tube, and finger strap of the PLMAs in both groups. Similar scores were observed for each part of the cleaned PLMAs in both groups, except for the outer surface of the PLMAs in Group 2 (P ＜ 0.05). Conclusions: We conclude that the use of an ultrasonic cleaner with an enzymatic solution may be effective to cleanse the outer surface of the PLMAs, but there were no differences in the total scores for both groups.

The Influence of Head Rotation on Proseal™ Laryngeal Mask Airway Sealing during Paediatric Myringotomy

Myringotomy with ventilation tube insertion in children involves turning the head from neutral to allow surgical access to the ear. In adults, rotation of the head from the mid-line generally increases the oropharyngeal leak pressure when a ProSeal laryngeal mask airway (PLMA) is used to manage the airway. There are concerns that these manoeuvres may distort or obstruct the paediatric airway. Paediatric sizes (1.5, 2.0 and 2.5) of the PLMA differ from the adult versions in that they do not have a dorsal cuff. This study examines the effect of these head position changes on the seal of the PLMA in children. Twenty-nine children (ASA 1-2, aged 0.9 to 7.5 years) scheduled for myringotomy were recruited. After PLMA insertion, oropharyngeal leak pressure and fibreoptic determined PLMA position scores were measured in the neutral position and with head rotation of 45 degrees to the left or right. Fibreoptic positioning scores were similar in all positions. Head rotation was associated with a statistically significant but modest increase in oropharyngeal leak pressure versus the neutral position (P < 0.05). After rotating the head from neutral, 38% (11 of 29) of subjects had an increase of oropharyngeal leak pressure of at least 2 cmH2O. Only 7% (2 of 29) of subjects had a decrease in oropharyngeal leak pressure with head rotation, the maximum decrease being 2 cmH2O. Airway obstruction did not occur in any of the positions. We conclude that the efficacy of the seal for the pediatric sizes PLMA is improved by head rotation for myringotomy.

A comparison of the Laryngeal Tube S and the LMA ProSeal laryngeal mask airway

Because the laryngeal mask technique is so essential to our specialty, we are frequently surprised by lack of appreciation for the newer LMA ProSeal™ (Laryngeal Mask Company, Henley-on-Thames, UK) [1]. We credit Dr Brimacombe and colleagues for describing an important malposition of the LMA ProSeal in 2001 [2]. They described how the LMA ProSeal can ‘fold over backwards’. In this position ventilation may be adequate and the practitioner gains a false sense of security that the position is satisfactory. The drain tube is also folded backward however, and cannot function as intended because it does not enter the oesophageal inlet. While folded backward, the LMA ProSeal does not provide any protection from the risk of regurgitation. A folded over LMA ProSeal may, in fact, act as a hypopharyngeal spring and pry open the upper oesophageal sphincter. We were surprised, therefore, by the publication of a study where the definition of ‘successful insertion attempt’ of the LMA ProSeal consisted simply of checking airway patency [3]. Among the 74 ‘successful’ insertions there were 12 patients in whom it was impossible to insert the orogastric tube. Evidently in these 12 patients the LMA ProSeal was folded backward. The purpose of the LMA ProSeal is to expand use of laryngeal mask technology to encompass patients at increased risk for aspiration. When the device is folded backward, as occurred in these 12 patients, this enhanced capability is completely defeated. The only proven technique to insert the LMA ProSeal into the oesophageal inlet with near complete success is by using a bougie-guided insertion method pioneered by Brimacombe and colleagues [4]. Another technique to verify correct positioning behind the larynx is to pass a well-lubricated orogastric tube through the drain tube and suction gastric fluid. A semiqualitative technique to test for foldover is the suprasternal notch test [5, 6]. This involves placing a membrane of children's bubble solution on the drain tube port. Tapping the suprasternal notch causes the membrane to bounce up and down when the LMA ProSeal is behind the cricoid cartilage (normal). If the membrane remains stationary, it can be assumed that the LMA ProSeal is folded backward. The device should be removed and reinserted. After using the suprasternal notch test to screen for foldover in over 3000 patients, we have always been able to pass an orogastric tube. However, there has been no prospective study to verify this simple and inexpensive test. In summary, just as it is automatic and prudent to exclude oesophageal intubation following every insertion of a tracheal tube, it should be automatic to exclude foldover following every insertion of the LMA ProSeal.

LMA ProSealTM in the veterinary anaesthesia - the animal is patient as well

LMA ProSealTM in the veterinary anaesthesia - the animal is patient as well

The Effect of Compressed Air Jet Cleaning on the Elimination of Postoperative Residual Protein from a ProSeal™ Laryngeal Mask Airway

TM laryngeal mask airways (PLMA's) have the potential to act as a vector for the transmission of prion diseases such as variant Creutzveldt-Jacob disease. This study tested the hypothesis that supplementary compressed air jet cleaning facilitates the removal of protein deposits on PLMA's after surgery. Methods: After clinical use, thirty PLMA's were randomly allocated to be washed by hand and with an autoclave (134 o C for 40 min) (group 1, n = 15), or by hand, autoclave and compressed air jet cleaning (1 min) (group 2, n = 15). In both groups, protein deposits were detected on PLMA's by erythrosine staining. A staining score designated as nil, mild, moderate, and severe was given to each site (outer, inner surface and edges of the cuff, airway and drain tube, finger strap) according to the percentage of stained surface area. The severity of staining was compared for masks prior to use and after cleaning the mask. Results: Despite the cleaning of masks, the staining score worsened on the outer, inner surface and edge of PLMA’s in both groups (P ＜ 0.05); however, a similar pattern was observed on each part of a cleaned PLMA for both groups. Conclusions: We conclude that compressed air jet cleaning for 1 min did not improve the removal of protein deposits on PLMA's after surgery. (Korean J Anesthesiol 2007; 53: 430～4)

Size 1 ProSeal??? Laryngeal Mask Airway in Neonates

To the Editor: As anesthesiologists who assess neonatal airways, both for resuscitation and anesthesia, we are involved in evaluating the safety and efficacy of devices for airway control (1). Goldmann et al. (2) states that the ProSeal Laryngeal Mask Airway (PLMA) size 1½ facilitates gastric tube placement in infants and forms a more effective seal than the same size Classic LMA (cLMA), allowing higher peak airway pressure during positive pressure ventilation (PPV). In previous articles, Goldmann et al., (3,4) Lopez-Gil et al., (5,6) and Wheeler (7) assess pediatric PLMA sizes (1½, 2, and 2½) with similar conclusions. Although the results with the size 1½ PLMA were encouraging for patients weighing 5–6 kg or more, Goldmann et al. found that the 1½ PLMA is too large for neonates. In a manikin-based comparative study, we recently tested the neonatal size 1 PLMA and size 1 cLMA (8). With IRB approval, we recently summarized our clinical experience in seven neonates who required PPV at birth, in whom we used the size 1 PLMA (Table 1). Their median (range) weight was 3.455 g (2.210–4.190 g), and their median gestational age was 39 wk (35–40). In all cases, a PLMA size 1 was easily inserted on the first attempt. Because the introducer strap is small and the absence of an integral bite-block renders the device very flexible, we could not position the device using the fingertip technique which we traditionally used with adult-sized PLMAs. Instead, we used the specific introducer provided by the manufacturer. We inflated the PLMA cuff and connected the device to a self-inflating bag, allowing effective PPV. We recorded the time elapsed from insertion of the PLMA into the newborn's mouth to the first inflation of the infants' lungs. We successfully placed an 8 or 10F gastric tube in all cases. Pulmonary auscultation and chest movement demonstrated good bilateral ventilation in all cases. Stethoscopic auscultation of the neck, just lateral to the thyroid cartilage, revealed only a single case with an audible leak, which did not compromise ventilation. We removed the PLMA when the neonate no longer tolerated it.Table 1: Performances of the Size 1 ProSeal™ Laryngeal Mask Airway in NeonatesThese are the first experiences with the size 1 PLMA. More data are needed, but these clinical impressions are encouraging. Further research will establish whether a size 1 PLMA will be useful for neonates who need high airway pressures for ventilation, which cannot be reliably achieved with the cLMA. Massimo Micaglio, MD Matteo Parotto, MD Department of Pharmacology and Anesthesiology [email protected] Daniele Trevisanuto, MD Vincenzo Zanardo, MD Department of Pediatrics University of Padova Padova, Italy

Airway Management with ProSeal LMA in a Patient with Osteogenesis Imperfecta

To the Editor: Osteogenesis imperfecta (OI) is a disease of connective tissue caused by mutations in one of the two genes encoding collagen type 1 (1). Its clinical features include susceptibility to bone fractures and retarded growth, as well as variable involvement of other connective tissues (1–3). Patients with OI often undergo surgery, most frequently orthopedic. There are several reports of hyperthermia during general anesthesia in these patients, although a direct relationship of OI to malignant hyperthermia is not substantiated (2). Difficult endotracheal intubation is common in patients with OI. The literature refers to the successful use of the laryngeal mask airway (LMA) and intubating LMA in these patients (3–5). In this letter we report a case of a 12-yr-old, 33-kg boy who was admitted for surgery because of right olecranon epiphysiolysis. He had OI, and he had experienced several previous fractures requiring surgical repair. Dantrolene sodium, sodium bicarbonate and cold IV solutions were available before anesthetic procedure. After we premedicated the patient with midazolam (0.06 mg/kg) and administered oxygen to him for 5 min, we induced anesthesia with propofol (2.5 mg/kg), atropine (0.1 mg/kg), and remifentanil (1 μg/kg). We administered rocuronium (0.6 mg/kg) for neuromuscular block. We maintained anesthesia with sevoflurane at 1%–2% end-tidal concentration and a remifentanil infusion at 0.2 μg/·kg−1·min−1. We inserted a size 3 ProSeal LMA with his head in neutral position. After emptying the patient's stomach, we inserted a thermistor temperature probe into the esophagus through the ProSeal LMA drain tube and located it in the lower quarter of the esophagus (the optimal location described by Mitchell et al.) (6). We monitored noninvasive arterial blood pressure, electrocardiogram, pulse oximeter, Fio2, ETco2, and esophageal core temperature. We did not find an increase of temperature, nor did we note any significant hemodynamic changes. We reversed the neuromuscular block with atropine (0.1 mg/kg) and neostigmine (0.3 mg/kg). Recovery was uneventful. We conclude that anesthesia with propofol, sevoflurane, and remifentanil provided hemodynamic stability and that the ProSeal™ LMA was a useful and easy method for securing the patient's airway and monitoring his core temperature continuously. M. Luisa Santos, MD Cristóbal Añez, PhD Ana Fuentes, MD Bárbara Méndez, MD Rocío Periñán, MD María Rull, PhD Department of Anaesthesiology Hospital Universitari de Tarragona Joan XXIII Tarragona, Spain [email protected]

Frenular Injury During Insertion of the ProSeal Laryngeal Mask Airway Using the Introducer Tool Technique

To the Editor: Microscopic mucosal injuries are common during laryngeal mask airway (LMA) insertion but macroscopic injuries are rare and few have been reported with the ProSeal™ LMA (1). We report a torn frenulum associated with ProSeal™ LMA insertion using the introducer tool technique. A 50-yr-old, 60-kg ASA physical status I male with no significant medical history was scheduled for a corneal transplant. Preoperative airway examination was normal. After induction of anesthesia, a size 5 ProSeal™ LMA was successfully inserted using the introducer tool technique. Some resistance was encountered at the back of the mouth, which was overcome by a slight increase in the force applied. The introducer blade was easily removed and the cuff was inflated with air 20 mL. The LMA was judged to be in its correct position as ventilation was easy, the bite block was between the teeth, and a 12F gastric tube was inserted at the first attempt. At the end of the procedure, the LMA was removed in the lateral position with the patient spontaneously breathing. There was a substantial amount of blood on the LMA. A torn frenulum was seen on examination (Fig. 1). The patient was re-anesthetized, tracheally intubated conventionally using a laryngoscope, and the laceration repaired by an oral surgeon (Fig. 2). Subsequent tracheal extubation and emergence were uneventful. There were no other sequelae.Figure 1.: Torn frenulum (tongue is retraced upwards, lower teeth are visible).Figure 2.: Repaired frenulum (lower teeth are visible).The injury was probably caused by accidental placement of the ProSeal™ LMA cuff between the tongue and base of the mouth, rather than the tongue and the roof of the mouth. Presumably the tongue was pushed back during insertion before slipping forward, allowing correct positioning. We strongly recommend that the LMA be placed between the tongue and the roof of the mouth under direct vision and that force is never applied during insertion. Such injuries may be less likely using the digital technique (as resistance is more easily detected) or the guided technique with a laryngoscope and gum elastic bougie (2) (as misplacement is rare). Zulkifli Mohamed Haris Wee Tze Loo Department of Anesthesia & Intensive Care Hospital Kuala Lumpur Kuala Lumpur, Malaysia Joseph Brimacombe Department of Anaesthesia and Intensive Care James Cook University Cairns Base Hospital Cairns, Australia [email protected]

The Size 1½ ProSeal™ Laryngeal Mask Airway in Infants: A Randomized, Crossover Investigation with the Classic™ Laryngeal Mask Airway

Many problems with the Classic laryngeal mask airway (CLMA) in infants are believed to be related to its inadequate cuff design. One of the main limitations of the CLMA is that the resulting low-pressure seal can be inadequate for positive pressure ventilation (PPV). The ProSeal LMA (PLMA), a new laryngeal mask airway with a modified cuff, has been shown to form a more effective seal than the CLMA in children. The first infant size PLMA, size 1(1/2), became available recently. We studied 30 anesthetized, nonparalyzed infants aged 15 mo (2-30 mo) and weighing 9 kg (5-12 kg). The CLMA and PLMA were inserted in random order into each patient. Airway leak pressure and maximum tidal volume were measured. Ease of insertion, quality of initial airway, and fiberoptic position were also determined. Gastric tube placement was assessed for the PLMA. The mean airway leak pressure in neutral head position (26.7 versus 18.9 cm H2O), maximum flexion (35.6 versus 28.2 cm H2O), and the mean maximum tidal volume (312 versus 260 mL) were significantly higher for the PLMA (P < 0.01). Air entered the stomach in eight patients with the CLMA but did not with the PLMA. Gastric tube placement was possible in all but one patient. In three patients, the use of the PLMA led to some degree of clinically relevant compression of the larynx. The size 1(1/2) PLMA seems to be a more suitable device for airway maintenance in infants than the same size CLMA. The ability to insert a gastric tube at the same time, and a significantly higher airway leak pressure than with the CLMA, may have important implications for its use for PPV in infants.

The Proseal™ LMA is a useful rescue device during failed rapid sequence intubation: two additional cases

We report two cases where the ProSeal laryngeal mask airway (PLMA) was successfully used as a rescue device, after failed tracheal intubation, during rapid sequence induction. The first case involved a 31-yr-old primigravida presenting for emergency Cesarean section for severe fetal distress. She had a grade 3 larynx and airway edema was observed during laryngoscopy. Attempts with a McCoy blade and gum elastic bougie failed to secure the airway. A size 4 PLMA was inserted with good airway control and surgery proceeded uneventfully. The second case involved a 51-yr-old man presenting for appendectomy. Following failed attempts at intubation, a size 5 PLMA was successful in securing his airway and surgery proceeded uneventfully. The correctly placed PLMA has potential advantages over the cLMA for airway rescue in the circumstance of failed emergency intubation in a patient with a potentially full stomach. In the two cases reported, the PLMA provided effective rescue of the airway.

The ProSeal™ Laryngeal Mask Airway Size Selection in Male and Female Patients in an Asian Population

The aim of this study was to investigate if size 5 compared with size 4 ProSeal laryngeal mask airway (PLMA) in Asian men and size 4 compared with size 3 ProSeal laryngeal mask airway (PLMA) in Asian women, would give a better glottic seal. We conducted a randomized crossover study involving 30 male and 30 female patients of Asian origin. Size 4 and size 5 PLMA were studied in men and size 3 and size 4 PLMA were studied in women. The patients were anaesthetized and paralysed and the PLMA was inserted with the introducer. The oropharyngeal leak pressure (OLP), ease of insertion, anatomical position, mucosal injury, visibility of cuff in the mouth and volume of air required to achieve an intracuff pressure of 60 cmH2O were studied. In male patients, oropharyngeal leak pressure was higher when size 5 PLMA was used (P < 0.001) and there was a higher incidence of mucosal injury (P = 0.025). For female patients, oropharyngeal leak pressure was higher with size 4 PLMA (P = 0.036) while the number of insertion attempts, anatomical position and mucosal injury were similar. The cuff was not visible in the oral cavity in any cases. The mean volume of air required to achieve an intracuff pressure of 60 cmH2O was less than the maximum recommended by the manufacturers. The size 5 PLMA in Asian men and size 4 PLMA in Asian women resulted in a more effective glottic seal. The use of size 5 PLMA in Asian men led to increased mucosal injury.

The ProSeal??? Has a Shorter Life-Span than the Classic??? Laryngeal Mask Airway

We tested the hypothesis that the life-span of the ProSeal laryngeal mask airway (LMA) is shorter than the Classic LMA. We also compared residual cuff volumes and changes in elastance and permeability with use. Six new size 4 ProSeal LMAs and 6 new size 4 Classic LMAs were tested. Each LMA underwent a simulated clinical use cycle until it failed the pre-use check tests. The simulated clinical use cycle comprised: i) inflating the cuff to the maximum recommended volume for 1 h; ii) immersion in an enzymatic solution for 3 min; iii) washing the external and internal surfaces; iv) automatic washing for 14 min (< or =85 degrees C); v) drying for 30 min (< or =75 degrees C); and vi) autoclaving at 134 degrees C for 4 min at 206 kPa. Before the first cycle and every 10 subsequent cycles, the cuff was inflated with 40 mL air and the intracuff pressure was measured immediately and 3 h later. The initial intracuff pressure was taken to be an inverse measure of the elastance or resistance to deformation, and the intracuff pressure change were taken as a measure of the permeability. The residual cuff volume was determined for 10 Classic and 10 ProSeal size 4 LMAs using a gas dilution technique. The mean +/- sd (range) longevity for the ProSeal LMA and Classic LMA was 82 +/- 23 (45-109) uses and 133 +/- 35 (76-176) uses, respectively. The ProSeal LMA has a shorter life-span than the Classic LMA (P = 0.01). For the ProSeal LMA, there was no change in elastance or permeability with use. For the Classic LMA, there was a decrease in elastance (P < 0.0001) and an increase in permeability (P < 0.0001) with use. The residual cuff volume was higher for the ProSeal LMA (2.6 +/- 1.3 mL versus 1.5 +/- 0.9, P = 0.04). We conclude that the life-span of the ProSeal LMA is shorter than the Classic LMA, but both exceed the manufacturer's recommendations of 40 uses. We recommend that reusable LMA devices be discarded when they fail the pre-use check tests, rather than after a specific number of uses.

Unilateral hypoglossal nerve injury following the use of a ProSeal™ laryngeal mask

We would like to report a complication following the use of a ProSeal™ laryngeal mask airway (PLMA) (Intavent Orthofix Ltd, Maidenhead, UK). A 28-year-old male required open reduction and internal fixation of a comminuted tibial plateau fracture. General anaesthesia was induced with infusions of propofol and remifentanil and his airway secured with a size 5 PLMA. The laryngeal mask was inflated with 40 ml of air. Anaesthesia was maintained with propofol, remifentanil, and nitrous oxide 70% in oxygen. Anaesthesia and surgery (which lasted 3.5 h) were uneventful. The PLMA was removed as the patient woke and was noted to be apparently overinflated. There were no immediate postoperative complications. The following day the patient complained of difficulty in swallowing and numbness on the left side of his tongue, present since shortly after waking up. Examination confirmed unilateral hypoglossal nerve injury. Throughout the rest of his time in hospital eating remained difficult. Full recovery of his hypoglossal nerve function was slow but complete at 4 months. Hypoglossal nerve, lingual nerve and recurrent laryngeal nerve injury have previously been reported during use of the classic laryngeal mask [1–4]. In most cases a full recovery was made. In one case hypoglossal nerve injury was accompanied by severe weight loss [1] and in another unilateral recurrent laryngeal nerve injury lead to permanent vocal cord paralysis [4]. The mechanism of injury is neuropraxia, due to pressure on the pharynx from the airway. In the case of the hypoglossal nerve this occurs at the medial side of the hyoid bone as the nerve crosses the greater cornu [5]. This is the first report of nerve injury associated with the PLMA. The PLMA has a larger cuff than the classic laryngeal mask airway and has a posterior extension. As a result the mask makes a larger area of contact with the pharynx and exerts lower pharyngeal pressures for the same intracuff volume [6]. The PLMA allows a better airway seal than the classic laryngeal mask airway for any given intracuff volume [6]. The rise in PLMA-airway seal is greatest for the first 10 ml of inflation, across the size range [6]. This, and other data suggest, that the PLMA is the least likely of the laryngeal masks to cause complications associated with increased pressure on pharyngeal mucosa, with the classic also better than the intubating laryngeal mask [7]. The 40 ml of air inserted into this PLMA represents the maximum volume that should be inserted into a size 5 PLMA. It is likely that the use of nitrous oxide and the long duration of surgery [8] both contributed to increased intracuff pressure, increased pharyngeal mucosal pressure and therefore neuropraxia. Audit elsewhere has shown that use of the maximum recommended volumes of air in all laryngeal masks routinely leads to intracuff pressures in excess of 120 cmH2O [9] and our own local audit has confirmed this. The practice of reducing the volume of air in the cuffs of laryngeal mask airways to half the recommended maximum has been shown not to interfere with mask function [10]. Brain has recommended both for the classic laryngeal mask airway and the PLMA that the maximum intracuff pressure should not exceed 60 cmH2O [11,12] and this information is contained in the instruction manuals of both devices [13,14]. At an intracuff pressure of 60 cmH2O, the pressure exerted on all areas of the mucosa by the PLMA is below that considered critical for mucosal perfusion [6]. Following this case, we have altered the practice in our hospital in order to try to prevent recurrence of this and similar complications. We have introduced cuff inflator/pressure gauges (VBM Mediztechnic, Sulz, Germany) to all areas where laryngeal mask airways are used allowing inflation to pressure of 60 cmH2O, and to enable monitoring of that pressure throughout anaesthesia. It appears that without use of such monitoring it is not possible to use the devices as recommended by the manufacturers. Dr Cook has received an honorarium from Intavent Orthofix Ltd, manufacturers of the laryngeal masks and has advised a number of airway companies.

Use of a gum elastic bougie in the oesophagus to guide the ProSeal™ LMA

During grade 3 or 4 laryngoscopy, blind mid-line insertion of the gum elastic bougie (GEB) will either ‘hold-up’ in the tracheo-bronchial tree or, if placed in the oesophagus, can be inserted up to its full length. If it is in the trachea, a tracheal tube may be inserted; if it is in the oesophagus, what does one do next, especially during a rapid sequence induction? If the GEB is withdrawn a little, a ProSeal™Laryngeal Mask Airway (Intavent Orthofix Ltd, Maidenhead, UK) with a well lubricated drain tube can be inserted along the GEB, preventing folding over of the laryngeal mask tip [1] and aiding optimum positioning. If ventilation is not possible, any cricoid pressure can be released prior to cricothyrotomy on a larynx now elevated by the ProSeal™ LMA. The drain tube acts as an exit route for gastric contents when the GEB is removed. Is this the simplest and easiest method to teach our trainees in their first 3 months, to deal with difficult laryngoscopy, intubation and ‘can’t intubate, can't ventilate' situations?