The PAxpress™ is an effective ventilatory device but has an 18% failure rate for flexible lightwandguided tracheal intubation in anesthetized paralyzed patients

PURPOSE: The PAxpress is a new, single-use, extraglottic airway device. We evaluate: 1) insertion success rates; 2) airway sealing pressure, ventilatory capability and calculated mucosal pressures (in vitro minus in vivo intracuff pressure) at 30-60 mL cuff inflation volume; 3) the feasibility of lightwand-guided tracheal intubation; and 4) the incidence of mucosal trauma. METHODS: Ninety anesthetized, paralyzed adults were studied. Airway management was by senior anesthesiologists with no prior experience with the PAX, but considerable experience with extraglottic airway devices and the flexible-lightwand. RESULTS: Insertion was successful at the first attempt in 95.5% (86/90) and at the second attempt in 4.5% (4/90). Mean +/- SD airway sealing pressure at 30, 40, 50 and 60 mL cuff inflation volume was 27 +/- 8, 29 +/- 9, 32 +/- 9 and 35 +/- 7 cm H(2)O respectively; expired tidal volume at airway sealing pressure was 16 +/- 6, 18 +/- 6, 19 +/- 5 and 19 +/- 6 mL.kg(-1); and calculated mucosal pressure was 38 +/- 14, 55 +/- 20, 56 +/- 19 and 57 +/- 20 cm H(2)O. Airway sealing pressure, expired tidal volume at airway sealing pressure and calculated mucosal pressures increased with cuff inflation volume (all: P < or = 0.0002). Esophageal leak was detected in 9% (8/90), but only at peak pressures > or = 35 cm H(2)O and cuff inflation volumes > or = 40 mL. Lightwand-guided intubation was successful in 82% (74/90) of patients. Mild, moderate and severe blood staining was detected in 40% (36/90), 15% (13/90) and 1% (1/90) respectively. Blood staining was more frequent after adjusting maneuvers (22/54 vs 32/36, P = 0.002). CONCLUSION: The PAX has a high insertion success rate and is an effective ventilatory device with a low risk of gastric insufflation, but has a moderately high failure rate for lightwand-guided intubation and is associated with a relatively high incidence of mucosal trauma. Mucosal pressures may exceed pharyngeal perfusion pressure.     

Emergency endotracheal intubation in pediatric trauma.

The purpose of this study was to determine the effectiveness and associated problems of emergency intubation in 605 injured infants and children admitted to the Children's Hospital of Pittsburgh in 1987. We identified 63 patients (10.4%) undergoing endotracheal intubation at the scene of injury, at a referring hospital or in our emergency department. Injuries were to the head (90.5%), abdomen (12.7%), face (11.1%), chest (6.3%), neck (3.2%); or were orthopedic (19%) or multiple (39.7%). Indications for intubation included coma (74.6%), shock (28.6%), apnea (22.2%), and airway obstruction (3.2%). Of 16 complications (25.4%), 13 were immediately life threatening: right mainstem intubation (5), massive barotrauma (2), failure of adequate preoxygenation (2), esophageal intubation (1), attempt at nasotracheal intubation in an open facial fracture (1), and extubation during transport (1). Three were late complications: vocal cord paresis (2) and subglottic stenosis (1). Airway complications led to PO2 less than 90 mm Hg in 7 of 12 on first ABG, compared to 9 of 44 in uncomplicated cases (p less than 0.05). Intubation attempts at the scene of injury were more often multiple, unsuccessful, and associated with airway complications. All four complication-associated fatalities were life-threatening scene complications. Nearly one half (44.4%, 28 of 63) had one of the following problems in respiratory management: major airway complication, PaO2 less than 90, or PaCO2 greater than 45 on either the first or second ABG after arrival at our emergency department. Head injury with coma is the most common setting for emergency intubation. Airway complications are common, and are more frequent in treatment attempt at the scene. Despite endotracheal intubation, injured children in our series remain at high risk for hypoxemia, elevated arterial PCO2, and major airway complications, all of which contribute to secondary brain injury.     

Crossover comparison of airway sealing pressures of 1.5 and 2 size LMA-ProSeal™ and LMA-Classic™ in children, measured with the manometric stability test

Objectives: To compare airway sealing pressures, air leak, optimal positioning of the LMA‐ProSeal? and LMA‐Classic? in children. Methods: A crossover, randomized study was conducted in children aged 6 months–7 years weighing <20 kg scheduled for minor elective surgery under GA with sevoflurane. Either a 1.5 or 2‐size LMA‐ProSeal? or LMA‐Classic? was inserted first. Optimal position of the devices was evaluated by fiberoptic bronchoscopy (FOB). Airway sealing pressures were determined under standardized conditions by the manometric stability test at the proximal end of the LMA device. Gas leak observed by auscultation over the neck and epigastrium was noted at these pressures. Results: Twenty‐seven children of mean ages 29.48 ± 19.81 months and mean weight 11.23 ± 3.28 kg were included for evaluation. Airway sealing pressures were noted to be similar: 23.11 ± 8.28 cm H₂O with LMA‐ProSeal? and 23.26 ± 8.21 cm H₂O with LMA‐Classic?. At these sealing pressures, air leak in the neck was observed in 21/27 children with LMA‐ProSeal? compared with 24/27 with LMA‐Classic? (P = 0.467). Optimal device positioning as viewed by FOB was seen in 14/27(51.8%) children with LMA‐ProSeal? and 15/27(55.6%) with LMA‐Classic?. Airway sealing pressures with suboptimal position of LMA‐ProSeal? was 22.23 ± 10.23 cm H₂O and with optimal position 23.93 ± 6.25 cm H₂O (P = 0.612). Conclusion: The LMA‐ProSeal? and LMA‐Classic? size 1.5 and 2 provide similar mean airway sealing pressures as assessed by the manometric stability test under standardized conditions, with similar air leak and optimal positioning.     

The LMA Fastrach™ facilitates fibreoptic intubation in oral cancer patients

PURPOSE: To compare ease of endotracheal intubation with the Intubating Laryngeal Mask Airway (ILMA) tracheal tube (TT; for LMA-Fastrach) and regular PVC TT (Portex) for nasotracheal fibreoptic intubation in oral cancer patients with a difficult airway. METHODS: 40 patients of physical status ASA I-II with a history of previous oral cancer surgery and/or postoperative radiotherapy scheduled for oral cancer surgery were randomly allocated by sealed envelopes to undergo tracheal intubation with either the ILMA TT or a standard TT. Ease of nasal passage of the TT and ease of tracheal intubation over the fibrescope was assessed. Peak airway pressures were assessed intraoperatively and postoperatively for 12 hr. RESULTS: The use of the ILMA TT increased the ease of nasotracheal intubation by increasing the percentage of successful tube placements at the first attempt (80%) in comparison with standard TT (35%); (P < 0.05). Peak airway pressures were found to remain low with the ILMA TT. None of the patients experienced any airway related complications. CONCLUSIONS: Use of a soft, flexible, nonkinking ILMA TT with a tapered tip design facilitates passage into the trachea over a fibreoptic bronchoscope and allows maintenance of lower airway pressures. The ILMA TT may be a useful adjunct for management of the difficult airway in oral cancer surgery.     

气管插管后静脉注射利多卡因可以减轻哮喘患者的支气管收缩

背景尽管预防性静脉注射利多卡因可以减轻气道对多种吸入刺激的反应性，但是其对哮喘患者插管后气道阻力的影响尚不清楚。本文旨在检验哮喘患者静脉注射利多卡因是否可以减轻插管诱发的支气管收缩。方法30例哮喘患者[年龄49．1±15．9岁（均数±标准差）]在常规麻醉诱导（依托咪酯0．3mg／kg，芬太尼5μg/kg，罗库溴铵0．6mg／kg，50％氧化亚氮）后行气管插管。分别在插管后即刻、5、10和15分钟测定气道阻力。插管后5分钟，静脉注射利多卡因（利多卡因2mg／kg在5分钟内静脉推注，并以3mg·kg^-1·h^-1的速度持续输注10分钟）或生理盐水。结果插管后即刻的气道平均阻力为23±12cmH2O·s·L^-1。注射盐水后气道阻力进一步增加38％，但是注射利多卡因后气道阻力较注射前下降（26％，P〈0．004）。结论气管插管后静脉注射利多卡因可以减轻哮喘患者的支气管收缩。     

Einsatz der ProSeal®-Kehlkopfmaske der Größe 3 bei Kindern

BACKGROUND: The low-pressure airway seal of the Classic laryngeal mask airway (CLMA) can be inadequate for positive pressure ventilation (PPV) in children. The ProSeal laryngeal mask airway (PLMA) forms a more effective seal of the airway than the CLMA and facilitates gastric tube placement in adults. The size 3 PLMA can be used in adults and children. METHODS: The CLMA and PLMA were studied in random order -- crossover -- in 30 anaesthetized, non-paralysed children (average age 10.6 years, average body weight 39 kg). Airway leak pressure, maximum tidal volume, ease of insertion, quality of initial airway and fiberoptic position were determined. Gastric tube placement was assessed for the PLMA. RESULTS: The mean airway leak pressure in neutral head position (27.0 vs. 16.8 cm H(2)O), maximum flexion (38.3 vs. 26.2 cm H(2)O) and maximum extension (21.1 vs. 14.2 cm H(2)O) as well as the mean maximum tidal volume (1432 vs. 1062 ml) were significantly higher (p<0.001) for the PLMA. Air insufflation into the stomach occurred with the CLMA but not with the PLMA. Gastric tube placement was possible in all patients. CONCLUSIONS: The high reliability of g-tube placement and the significantly increased airway leak pressure seem to make the size 3 PLMA a more suitable device for PPV in children than the same size CLMA.     

头颈位置对应用三种声门上通气装置时口咽部漏气压和套囊位置的影响

背景使用声门上通气装置时,例如引流型喉管（LTS）、食管引流型喉罩（PLMA）、喉周通气道（CobraPLA）,口咽部漏气压和套囊位置会随着头颈位置的变化而改变。本研究测试了使用上述3种喉罩时头颈位置改变目『起的口咽部漏气压和套囊位置的变化。方法139例接受择期小型手术患者（年龄为18—70岁）随机接受使用3种声门上通气装置中的一种。测量以下4种头颈部位置时的口咽部漏气压和套囊内压：头正中位、前屈45°、后仰45°以及右偏45°,同时评估不良反应（如通气困难和胃胀气）。结果PLMA漏气压最低,体位为头后仰时漏气压为18．5cmH2O,LTS和CobraPLA分别为23．9和26．8cmH2O（P〈0．001）;头颈偏转时PLMA漏气压为25．0cmH2O,LTS和CobraPLA分别为29．4和28．5cmH2O（P〈0．005）。使用CobraPLA时,45例患者中有37例在口咽部漏气之前出现胃胀气。在使用LTS的患者中有7例颈前屈的患者出现了通气困难,需要使用气管插管。结论在头后仰和偏转时,PLMA比LTS和CobraPLA显著降低口咽部漏气压。使用LTS和CobraPLA时要注意头颈部位置,可能会发生胃胀气和通气困难。     

An evaluation of the modified Airway Management Device

We evaluated the modified Airway Management Device (AMDTM) in 60 spontaneously breathing anaesthetised patients. The insertion and removal of the device was very easy and atraumatic. The airway was secured on the first attempt in 41 patients (70%; 95% CI 57-80%). The most important problem was loss of airway, which occurred in 11 patients (19%; 11-30%) during maintenance of anaesthesia. The AMD was dislodged during maintenance in one patient. There was a loss of the airway in 12 patients (20%; 12-31%); in 10, it was maintained with simple airway manoeuvres or a laryngeal mask airway and tracheal intubation was required in two patients. Ten of these patients were male and two were female; the failure rate was 33% (12-31%) among the male patients and 6% (2-22%) among the female patients. The cuff volumes ranged from 4 ml to 80 ml and cuff pressures from 6 cm H2O to 92 cm H2O. Blood was seen on removal in three patients (6%; 2-16%) and nine patients (18%; 10-30%) experienced sore throat after removal of the device.     

Comparison of laryngeal mask airway (LMA)-Proseal™ and the LMA-Classic™ in ventilated children receiving neuromuscular blockade

PURPOSE: To determine whether a functional difference exists between the size 2 laryngeal mask airway (LMA)-Classic (CLMA) and LMA-Proseal (PLMA) in anesthetized children who have received neuromuscular blockade. Airway leak during intermittent positive pressure ventilation (IPPV) and adequacy of fibreoptic laryngeal view were the primary study outcomes. METHODS: A randomized, controlled, single-blinded study of 51 ASA I or II children weighing 10-20 kg was undertaken. The anesthetic technique was standardized. Following insertion of the LMA and cuff inflation to 60 cm H(2)O, we measured oropharyngeal leak pressure and gastric insufflation and leak fraction during IPPV, and evaluated the adequacy of fibreoptic view. RESULTS: Oropharyngeal leak pressure measured by neck auscultation was higher for the PLMA compared to the CLMA (23.7 vs 16.5 cm H(2)O, P = 0.009) but, when measured by the inspiratory hold maneuver was not significantly different (24.8 vs 20.3 cm H(2)O, respectively, P = 0.217). Leak fraction values were similar for the CLMA and the PLMA (21.2%. vs 13.3%, respectively, P = 0.473). A satisfactory view of the larynx was obtained more frequently in the PLMA group (21/25 vs 10/25, P = 0.003). Gastric insufflation during leak determination was more common with the CLMA (12/26 vs 2/25 CLMA vs PLMA, respectively, P = 0.006). CONCLUSION: In children undergoing IPPV with neuromuscular blockade, the size 2 PLMA is associated with a higher leak pressure by auscultation and less gastric insufflation compared to the CLMA. Leak pressures assessed by manometric stability are similar with these two devices. The improved fibreoptic view of the larynx through the PLMA may be advantageous for bronchoscopy.     

Problems and complications in airway management by endotracheal intubation and laryngeal mask airway

The endotracheal intubation and laryngeal mask airway confer many advantages for surgical patients. However, a number of problems and complications with airway management by endotracheal intubation and laryngeal mask airway have been documented. In this report, several problems by using endotracheal intubation (e.g. hoarseness, arytenoids dislocation) and laryngeal mask airway (e.g. aspiration, oropharyngeal leak, gastric distension) are summarized.     

Vergleich von zwei Larynxmaskenmodellen zur Atemwegssicherung bei Patienten mit Immobilisation der Halswirbelsäule

BACKGROUND: Reduced cervical spine mobility can impair laryngoscopy and tracheal intubation. Supraglottic airway devices can be important alternatives for oxygenation under these circumstances. The Ambu laryngeal mask (ALM) and the LMA-Classic (LMA) are compared in patients with immobilization of the cervical spine.METHODS: In 60 patients scheduled for elective ambulatory interventions, ALM or LMA were inserted after cervical immobilization with an extrication collar and assessment of laryngoscopic view. Insertion time (removal of facemask until first tidal volume), number of insertion attempts, airway leak pressure (cuff pressure 60 cm H(2)O), intraoperative complications and postoperative complaints were assessed.RESULTS: Demographical data, insertion attempts, insertion time (ALM 15.6+/-4.4 s, LMA 15.5+/-4.9 s) and airway leak pressure (ALM 25.6+/-5.2 cm H(2)O, LMA 26.5+/-6.5 cm H(2)O) were comparable. Traces of blood were found in 6 LMAs and 3 ALMs after removal, mild trouble with swallowing (visual analogue scale, VAS 2-4) in the recovery room and after 24 h were complaints by 1 ALM and 2 LMA patients.CONCLUSIONS: LMA-Classic and Ambu laryngeal masks are suitable for rapid and reliable airway management in patients with cervical immobilization.     

A cohort evaluation of the Laryngeal Mask Airway‐Supreme™ in children

Objectives: To assess the clinical performance of the laryngeal mask airway‐Supreme in children. Aim: The purpose of this prospective audit was to evaluate the feasibility of the laryngeal mask airway‐Supreme in clinical practice and generate data for future comparison trials. Background: The laryngeal mask airway‐Supreme is a new second‐generation supraglottic airway that was recently released in limited pediatric sizes (sizes 1, 2). Methods: One hundred children, ASA I‐III, newborn to 16 years of age, and undergoing various procedures requiring a size 1, 2, or 3 laryngeal mask airway‐Supreme were studied. Assessments included insertion success rates, airway leak pressures, success of gastric tube insertion, quality of airway, and perioperative complications. Results: The first‐time insertion success rate was 97%, with an overall insertion success rate of 100%. The mean initial airway leak pressure for all patients was 22.3 ± 6.6 cm H₂O. Gastric tube placement was possible in 98% of patients. Complications were noted in six patients: coughing or laryngospasm (n = 3), sore throat (n = 1), and dysphonia (n = 2). Conclusions: The laryngeal mask airway‐Supreme was inserted with a high degree of success on the first attempt by clinicians with limited prior experience with the device. It was effectively used for a variety of procedures in children undergoing spontaneous and mechanical ventilation with minimal complications. The leak pressures demonstrated in this study, along with access for gastric decompression, suggest that the laryngeal mask airway‐Supreme may be an effective device for positive pressure ventilation in children.     

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.     

The size 1(1/2) 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.     

Die sichere Handhabung der Larynxmaske bei Augenoperationen

Background: We prospectively used the laryngeal mask airway (LM) in eye surgery to evaluate: 1) the limits of safe handling; 2) the feasibility of its use in long operative procedures, and 3) whether patients with higher anaesthetic risk (hypertension, asthma, children) may profit from the LM. Methods: In 792 patients leak pressure, cuff volume, duration of anaesthesia, and complications were noted; 33 were children under 10 years of age, 100 had hypertension or severe asthma. In 54 patients cuff volume was increased to measure its influence on leak pressure; in 241 leak pressure was also measured at the end of the procedure; in 31 cuff pressure was measured under standard conditions over time; in 7 dead space was evaluated with the BANALYZER program; and in 300 blind endotracheal suction was attempted through the LM. Results: Limits for the safe use of the LM were a leak pressure?<12?cm H₂O combined with insufficient spontaneous ventilation (CO₂et >7 vol.%; n=14), dislocation with gastric inflation (n=2), and bronchial secretions (n=1), as blind suctioning of the trachea through the LM was possible in only 1 out of 300 attempts. These limits could be recognised before the start of the operation in most cases. Laryngospasm or closure of the glottis (n=36, 4.5%) was treatable and did not necessitate abandoning the use of the LM. Mean leak pressure was 17.7±4.8?cm H₂O, showing a comparable distribution in adults and in children and being improved mainly by position changes of the LM, but not by changes in cuff volume. No gas leak occurred when the individual peak inspiratory pressure was equal to or lower than the measured leak pressure except in children. Dead space was almost halved by the LM compared to a face mask (90±13 vs. 162±31?ml; P<0.05), allowing spontaneous breathing to be adequate even when manual assistance of ventilation was not possible (n=14, 1.8%). In patients with sufficiently high leak pressures, the LM was safely used for long operations (up to 240?min), as leak pressure did not change over time. When only a low leak pressure could be achieved, deep breaths could be delivered by prolongation of the inspiratory time, thereby preventing atelectasis if tidal volume was limited. Cuff pressure rose to about 100?cm H₂O within 60?min and should be monitored. In children, air was aspirated intermittently out of the stomach in procedures longer than 30?min; in adults, we monitored and buffered gastric contents where necessary. In patients at risk, the LM stimulates the circulation and bronchial reactivity less than an endotracheal tube. Children could be discharged earlier from the recovery room (0.45–1.5?h vs. ≥2?h after neuromuscular relaxation and intubation). Conclusion: Limits for the use of the LM in eye surgery are delineated. Within these limits, the LM offers control over the airway comparable to that of an endotracheal tube with less stimulation. The LM has to be applied by an experienced user, and has advantages in eye surgery.     

Anterior skull base surgery without prophylactic airway diversion procedures.

OBJECTIVE: Although anterior skull base surgery has become a relatively safe and effective procedure, postoperative complications remain a serious problem. One of the most devastating complications of anterior skull base procedures is tension pneumocephalus (TP). In order to prevent TP, authors have recommended the use of prophylactic airway diversion procedures, such as prolonged endotracheal intubation or prophylactic tracheostomy. However, these procedures may mask neurologic deterioration, delay treatment, and prolong rehabilitation. The purpose of this study was to determine the need for airway diversion procedures in anterior skull base surgery. STUDY DESIGN: Eighty-five patients underwent anterior skull base operations through the subcranial approach without prophylactic airway diversion. Sixty-four patients underwent resection of tumors, 12 patients underwent repair of cerebrospinal fluid leak, 6 patients underwent surgery due to anterior skull base fungal infections, and 3 patients underwent anterior skull base reconstruction procedures. RESULTS: The complication rate of TP was 1.2% (1/85). This complication rate is similar to that previously reported for operations performed with airway diversion procedures. CONCLUSION: Prophylactic airway diversion procedures are unnecessary in routine anterior skull base operations. Airway diversion should be indicated only when factors that might predispose the patient to risk of TP have been identified (ie, chronic cough or obstructive pulmonary diseases).     

Monitoring airway pressure in pediatric anesthesia: an experimental model of intratracheal medication and pressure-volume loops

BACKGROUND: In the monitoring of anesthesia, airway pressure is measured in the ventilator or at the closest possible connection to the endotracheal tube. OBJECTIVE: To compare the airway pressures and pressure-volume loops obtained before connection to the endotracheal tube with those obtained in the trachea. MATERIAL AND METHODS: We carried out a single-blind prospective observational study on ASA 1 patients between the ages of 7 and 12 years ventilated in volume-control mode with an inspiration-to-expiration ratio of 1:2. Intratracheal and extratracheal peak and plateau pressures and pressure-volume loops were recorded. A special device was designed to monitor intratracheal pressure. Both sensors were connected to the same spirometric analysis system. The variables were measured on intubation and 5, 10, 15, 20, 30, 40, 50, and 60 minutes after intubation. The recorded pressures were compared using the t test, the Pearson product moment correlation coefficient (r), and the Spearman rank correlation coefficient (p), and regression models were fit to the data. RESULTS: Seventy-one patients were enrolled. The mean (SD) pressure difference between the 2 systems was 3.5 (0.35) cm H2O (P < .01) and no differences between the endotracheal peak pressures and the plateau pressures were observed. The intratracheal areas of the pressure-volume loops were 15% lower than the extratracheal areas. The value of r for the correlation between the intratracheal peak and plateau pressures was 0.998 (P < .01). The value of r for the correlation between the intratracheal and extratracheal peak pressures was 0.981 (P < .01). Analysis of variance confirmed the linear relationship. CONCLUSIONS: The difference between the intratracheal and extratracheal pressure measurements is due to the different locations at which the measurements are taken.     

An evaluation of the insertion and function of a new supraglottic airway device, the King LT, during spontaneous ventilation

Trials of the King LT trade mark (LT, King Systems, Noblesville, IN) in controlled ventilation of the lungs have shown that it is an effective supraglottic airway device. We designed this study to evaluate the King LT regarding ease of insertion, position within the airway, and anatomic sealing properties during spontaneous ventilation in 50 ASA physical status I-III, Mallampati I-III, adult patients undergoing routine general anesthesia. Anesthesia was induced with up to 2 microg/kg fentanyl and 1.5-2 mg/kg propofol and maintained with 70% N2O/30%O2 and isoflurane. Insertion time, oropharyngeal leak pressures, fiberoptic position, and spirometry and hemodynamic data were recorded. Any complications were noted. Insertion was determined to be easy and a patent airway was achieved in all patients. First, second, and third attempt insertion rates were 86%, 12%, and 2%, respectively. Time to place the King LT trade mark was <5 s in 90% of cases. Baseline leak pressures were 31 +/- 8.8 cm H2O (17-50 cm H2O). Complications included laryngospasm (1) and coughing (3) on extubation. The incidence of sore throat at 1 h and 24 h postoperatively was 22% and 15%, respectively. The King LT trade mark is a simple and reliable supraglottic airway device for airway management during spontaneous ventilation.     

Air leakage around endotracheal tube cuffs

BACKGROUND AND OBJECTIVE: To compare the recently introduced Microcuff endotracheal tube with conventional tubes in respect of the cuff pressures required to prevent air leakage. METHODS: The following tubes (ID 7.0mm) were compared: Microcuff HVLP ICU, Mallinckrodt HiLo, Portex Profile Soft Seal, Rüsch Super Safety Clear and Sheridan CF. Fifty patients undergoing endotracheal intubation with a cuffed tube of internal diameter 7.0 mm were studied. Tracheas were intubated using one of the endotracheal tubes in random order. Cuff pressure to prevent air leakage at standardized ventilator setting (peak inspiratory pressure 20 cmH2O/PEEP 5 cmH2O/respiratory rate 15 breaths min(-1)) was assessed by auscultation of audible sounds at the mouth. Patients characteristics and cuff pressures from each brand were compared to the Microcuff group using the Mann-Whitney U-test (P < 0.05 was chosen as the level of statistical significance). RESULTS: Patients' median age (range) was 14.2 (12.0-17.1) yr, body weight 57.5 (40.0-81.9) kg and length 164.9 (146.5-190.0) cm. No significant differences in patients' characteristics were found between groups. Mean cuff pressure (all tubes) required for air sealing was 19.1 (8-42) cmH2O. The Microcuff tube required significantly lower sealing pressures (9.5 (8-12) cmH2O) compared to the other brands of endotracheal tube (P < 0.05, Mann-Whitney U-test). CONCLUSION: The Microcuff endotracheal tube with its ultra-thin polyurethane cuff membrane required the lowest sealing pressure to prevent air leakage. These features are potentially of interest for long-term intubated patients and for cuffed endotracheal tubes in children, allowing tracheal sealing at lower cuff pressures implying less damage to the trachea.