Anesth Analg 2003;96:1214-1217
© 2003 International Anesthesia Research Society
GENERAL ARTICLES
A Comparison of the PAxpressTM and Face Mask Plus Guedel Airway by Inexperienced Personnel After Mannequin-Only Training
V. Dimitriou, MD DEAA*,
G. S. Voyagis, MD
,
C. Iatrou, MD*, and
J. Brimacombe, MB ChB, FRCA, MD
*Department of Anaesthesia, University of Thrace;
Department of Anaesthesia, Sotiria Hospital, Greece; and
Department of Anaesthesia and Intensive Care, University of Queensland and James Cook University, Cairns Base Hospital, Australia
Address correspondence and reprint requests to J. Brimacombe, MD, Department of Anesthesia and Intensive Care, Cairns Base Hospital, The Esplanade, Cairns 4870, Australia. Address e-mail to jbrimacombe{at}austarnet.com.au
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Abstract
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The PAxpressTM (PAX) is a new extraglottic airway device consisting of an anatomically curved tube, an inflatable circular cuff in the midsection, a noninflatable gilled conical cuff at the distal end, and an anterior-facing, rectangular hooded vent between the two cuffs. We compared the ability of nurses with no previous airway management experience to ventilate the lungs of 45 ASA physical status I and II anesthetized, paralyzed patients using either the PAX or face mask and Guedel airway (FM/GA) after mannequin-only training. Nurses were asked to ventilate the patient to an expired target tidal volume of 7 mL/kg and then to the maximum tidal volume achievable. The FM/GA was used first and the then the PAX. The target tidal volume was achieved in all patients with both devices. There were no differences in the time taken (PAX, 41 ± 15 s; FM/GA, 39 ± 25 s) or the number of insertion attempts to achieve the target tidal volume. There were no differences in the frequency of esophageal leaks at the target (PAX, 9%; FM/GA, 4%) and maximum tidal volume (PAX, 51%; FM/GA, 49%). The maximal tidal volume (1261 ± 306 versus 958 ± 220 mL; P < 0.0001) and peak airway pressure (37 ± 5 versus 28 ± 6 cm H2O; P < 0.0001) was larger for the PAX, but blood was detected more frequently (22% versus 0%; P = 0.001). We conclude that ventilation to a target tidal volume of 7 mL/kg in anesthetized, paralyzed adults is equally successful for the PAX and FM/GA by inexperienced nurses after mannequin-only training. However, the maximal tidal volume and peak airway pressure is larger and airway trauma more common with the PAX.
IMPLICATIONS: Ventilation to a target tidal volume of 7 mL/kg in anesthetized, paralyzed adults is equally successful for the PAxpressTM (PAX) and Face Mask/Guedel Airway by inexperienced nurses after mannequin-only training. However, the maximal tidal volume and peak airway pressure is larger and airway trauma more common with the PAX.
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Introduction
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The PAxpressTM (PAX; Vital Signs Inc, Augusta, GA) is a new, single-use, extraglottic airway device. It consists of an anatomically curved tube with an inflatable circular cuff in the midsection that forms a seal in the proximal pharynx for ventilation and a noninflatable gilled conical tip at the distal end that forms a no-pressure seal in the hypopharynx for prevention of regurgitation and gastric insufflation and anchors the PAX in the hypopharynx for a stable, hands-free airway (Fig. 1). Between the cuff and tip on the inner curve is a rectangular hooded vent that faces anteriorly towards the glottic inlet. The PAX is intended to function as a ventilatory device or airway intubator for anesthesia or cardiopulmonary resuscitation. In two preliminary studies, we found that the PAX had a high insertion success rate and was an effective ventilatory device with a low risk of gastric insufflation (1,2) , but there are no data about its use by inexperienced personnel. In the following study, we compared the ability of nurses with no previous airway management experience to ventilate patients using either the PAX or Face Mask/Guedel airway (FM/GA) after mannequin-only training.
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Methods
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Three nurses with no airway management experience attempted to ventilate the lungs of 45 ASA physical status I and II anesthetized, paralyzed patients undergoing elective surgery in the supine position using the PAX or FM/GA. Ethical committee approval and written informed consent were obtained. Patients were excluded if they were <18 yr old, had respiratory tract pathology, were at risk of aspiration, or had an intercisal distance <20 mm. Training consisted of supervised practice with mannequins (three sessions lasting 1 h each). The time given to training was equal between devices. Each nurse performed 15 insertions with each device.
Induction was with fentanyl 1 µg/kg followed by propofol 1.5–3.0 mg/kg. Maintenance was with O2 and sevoflurane 1%–3%. Neuromuscular blockade was achieved with cisatracurium 0.15 mg/kg. The fresh gas flow was 7 L/min. Monitoring was applied preinduction and included an electrocardiograph, pulse oximeter, gas analyzer, noninvasive blood pressure monitor, tidal volume monitor (Draeger digital tidal monitor, Draeger, Luebeck, Germany), and airway pressure monitor. The anesthesiologist ventilated patients via a face mask for 3–5 min. When the patient was stable, the face mask was disconnected from the circle anesthesia breathing system and placed beside the patient’s head alongside an appropriately sized FM/GA, a lubricated PAX, and a 60-mL syringe. The nurse, who was blinded to the performance of the anesthesiologist during face mask ventilation, was asked to ventilate the patient to a predetermined expired target tidal volume of 7 mL/kg and then to a maximum tidal volume. The nurse was given a maximum of 3 min to obtain the target tidal volume. The FM/GA was used first and the PAX second. The PAX was inserted with the head and neck in the neutral position and the cuff inflated with 50 mL of air. No assistance was received, and the anesthesiologist only intervened if the SpO2 decreased less than 95% or frank blood was seen on the PAX or FM/GA. A maximum of three attempts was allowed. A failed attempt was defined as removal of the PAX or FM/GA from the mouth.
The following data were collected by the anesthesiologist: (a) time taken from first picking up the airway device to achieving the target tidal volume, (b) the number of insertion attempts before achieving the target tidal volume, (c) the maximum tidal volume and peak airway pressure, (d) the presence or absence of an esophageal leak at the target tidal volume and at the maximum tidal volume, and (e) the presence or absence of blood on the FM/GA or PAX at removal. In addition, the nurses were asked to evaluate the procedure as easy or difficult. Esophageal leaks were detected by placing a stethoscope over the epigastrium (3).
Skill acquisition was determined by comparing the performance of the first 5, the second 5, and the last 5 patients. Statistical analysis was with one-way analysis of variance with Bonferroni post hoc test for multiple comparisons, paired or unpaired t-test, 
2 test, and Fisher’s exact test. Significance was taken as P < 0.05.
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Results
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The mean age (range), height, and weight was 53 yr old (22–80 yr), 165 cm (153–181 cm), and 73 kg (56–102 kg), respectively. The male-to-female ratio was 19:26. Comparative data are presented in Table 1. The target tidal volume was achieved in all patients with both devices. There were no differences in the time taken or the number of insertion attempts required to achieve the target tidal volume. There were no differences in the frequency of esophageal leaks at the target and maximum tidal volume. The maximal tidal volume (1261 ± 306 versus 958 ± 220 mL; P < 0.0001) and peak airway pressure (37 ± 5 versus 28 ± 6 cm H2O; P < 0.0001) was larger for the PAX, but blood was detected more frequently in the PAX (22% versus 0%; P = 0.001). There was no evidence for skill acquisition with either device other than for maximal tidal volume with the face mask plus FM/GA, which increased when comparing the first, middle, and last five cases (865 ± 186 mL versus 933 ± 186 mL versus 1076 ± 225; P = 0.02). There were no differences in performance among the three nurses.
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Discussion
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The time taken to achieve the target tidal volume and the number of insertion attempts were similar for the FM/GA and PAX. This suggests that both the FM/GA and PAX are equally effective ventilatory devices for inexperienced personnel after mannequin-only training. Interestingly, our success rate for the FM/GA was higher than usually reported for inexperienced personnel (4–7) . This may be related to the high level of training.
The incidence of esophageal leaks was similar for the FM/GA and PAX. This is surprising because the gilled conical distal portion should form a plug in the hypopharynx. This suggests that the PAX was not correctly positioned in many patients or the relatively good seal in the proximal pharynx allowed large airway pressures to develop that bypassed the hypopharyngeal seal. However, esophageal leaks were un- common, even at large airway pressures, in the preliminary studies by anesthesiologists (1,2) , suggesting malposition was the main contributing factor. Perhaps the pattern of manual ventilation was also different for nurses when squeezing the bag. Gastric insufflation is more likely with the classic laryngeal mask airway if it is malpositioned (8). The frequent incidence of esophageal leaks implies that the PAX cannot be relied on by nurses to prevent gastric insufflation or regurgitation after mannequin training.
We found that the maximum expired tidal volume and peak airway pressures were larger with the PAX than the FM/GA. This suggests that the PAX has greater capability as a ventilatory device than the FM/GA. This is probably related to the PAX forming a better seal with the proximal pharynx than the face mask forms, with the face or the PAX forming a clearer passage between the proximal pharynx and the glottic inlet than the FM/GA forms between the mouth and glottic inlet. We elected to compare the PAX with the FM/GA rather than another cuffed extraglottic airway device because most resuscitation algorithms still recommend the FM/GA as the first-line method.
We found that the incidence of bleeding was more frequent with the PAX. This is not surprising because the PAX penetrates further into the pharynx than the FM/GA and involves inflation of a proximal pharyngeal cuff. However, bleeding with the PAX would be easier to detect because of the cuff allowing blood to collect. The incidence of bleeding was similar to other extraglottic airway devices such as the classic laryngeal mask airway (9), cuffed oropharyngeal airway (10), and esophageal tracheal Combitube (11). The bleeding may be related to trauma on insertion or mucosal ischemia from the inflated cuff. Calculated mucosal pressures with the PAX may exceed pharyngeal mucosal perfusion pressure (2,12) . The presence of blood may have implications for pharyngolaryngeal complaints and cross-contamination.
We found no evidence of skill acquisition for the PAX and some evidence of skill acquisition with the FM/GA. A larger study is required to determine the extent to which FM/GA skills would continue to improve. However, it is likely that PAX skills will also improve but over a larger number of uses. Also, the capital cost of the PAX is approximately three times that of a single-use FM/GA.
Our study has a number of limitations. First, the order in which the airway devices were used was not randomized. This was because we anticipated that more trauma would occur with the PAX, and any bleeding would interfere with the performance of the FM/GA. It is possible that the FM/GA contributed to the trauma with the PAX. Second, data collection was not blinded to the device being used, which is a possible source of bias. Third, only three nurses participated in the study, making the results less applicable to the general nursing population. Fourth, our patients were anesthetized and paralyzed to provide ideal insertion conditions. Patients requiring cardiopulmonary resuscitation often have intact reflexes, and it is likely that success rates would decrease in this situation.
We conclude that ventilation to a target tidal volume of 7 mL/kg in anesthetized, paralyzed adults is equally successful for the PAX and FM/GA by inexperienced nurses after mannequin-only training. However, the maximal tidal volume and peak airway pressure is larger and airway trauma more common with the PAX.
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References
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- Voyagis GS, Iatrou C, Dimitriou V. Safety of the new pharyngeal airway (PAXexpress) as a ventilatory device: preliminary data (abstract). Eur J Anaesthesiol 2002; 19: A143
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Accepted for publication November 19, 2002.
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Abstract
Introduction
