OBJECTIVE. Proficiency in airway management in children is difficult to acquire and maintain for prehospital providers. The laryngeal mask airway is a relatively new airway device. Its ease of use makes it an attractive potential alternative to endotracheal tubes in pediatrics. The objective of this study was to investigate whether, in simulated cardiopulmonary arrests in children, the use of laryngeal mask airway, compared with endotracheal tubes, results in shorter time to effective ventilation when performed by prehospital providers.
METHODS. A randomized, crossover study was conducted in a local paramedic training program. Fifty-two emergency medical technicians agreed to participate. After a 2-hour training session, an arrest scenario was presented to each participant by using an infant-sized human patient simulator. The participants were randomly assigned first to use 1 of the 2 devices. Time to successful ventilation was recorded. Number of attempts and results were recorded. After the airway was secured successfully, the scenario was repeated with the alternative device.
RESULTS. The mean ± SD length of time to effective ventilation was 46 seconds when using endotracheal tubes and 23 seconds when using laryngeal mask airway, with a mean difference of 23 seconds. The mean number of attempts to achieve effective ventilation was 1.27 when using endotracheal tubes and 1.1 when using laryngeal mask airway. There were 9 (17%) episodes of esophageal intubations and 14 (27%) episodes of right main-stem intubations in the endotracheal tube group, and there were 5 (9.5%) episodes of malposition in the laryngeal mask airway group.
CONCLUSIONS. In simulated pediatric arrests, the use of laryngeal mask airway, compared with endotracheal tubes, led to more rapid establishment of effective ventilation and fewer complications when performed by prehospital providers.
Respiratory and cardiac arrests are rare but devastating occurrences in children. When a pediatric arrest occurs in the prehospital setting, the odds for survival with good neurologic function are very poor.1,2 Studies of adult patients clearly demonstrated that early initiation of effective cardiopulmonary resuscitation is associated with survival. In children, respiratory failure usually precedes cardiac arrest.3
The optimal procedure to establish effective oxygenation and ventilation in children in the prehospital setting is still to be determined. Despite a lack of strong evidence for the utility of endotracheal tubes (ETTs) in the prehospital setting, the use of the device is widely taught to emergency medical services (EMS) personnel. Many inherent difficulties are associated with the use of ETTs in children. Research showed that the outcome in pediatric arrest was not improved by the use of ETTs, as compared with bag-valve-mask ventilation, yet was associated with more complications, some of which were severe.4
The laryngeal mask airway (LMA) is a relatively new addition to the armamentarium of airway devices (Fig 1). Both physicians and nonphysicians can acquire the skills necessary to insert the device properly with a minimal amount of training.5–7 Previous research suggested that it may be associated with a higher success rate and a lower rate of complications than ETTs.6 Despite the availability of the device, the use of LMA in the pediatric setting has been limited mostly to case reports.8,9 We report a study that systematically investigated the use of LMA in pediatric prehospital arrests by using a high-fidelity human patient simulator (HPS).
We hypothesized that in simulated settings of respiratory arrests in children, the use of LMA, compared with ETTs, would result in shorter time to effective ventilation when performed by EMS personnel. In addition, we hypothesized that there would be fewer complications when using LMA.
We conducted a randomized study with crossover comparing the use of LMA with ETTs in a local paramedic training program in New Haven, Connecticut. This project was approved by the human investigation committee of Yale University School of Medicine with consent waiver.
All EMS personnel who were undergoing initial training or recertification for paramedic status were eligible. The participants were blinded to the hypotheses of the project. In each session, pediatric emergency medicine attending physicians administered a 2-hour training session with lectures and hands-on time with both LMA and ETTs. On the same day, after a short recess after the training session, a cardiopulmonary arrest scenario was presented to each participant by using an infant-sized HPS, the SimBaby (Laerdal, Oslo, Norway). The participants were randomly assigned first to use 1 of the 2 devices. The selected equipment of the appropriate sizes was arranged next to the HPS, within easy reach. A 4.5mm OD noncuffed ETT (Mallinckrodt, St Louis, MO), a Miller 1 laryngoscope blade and handle, a size 1.5 LMA (LMA of North America, San Diego, CA), and a 150-mL infant-sized self-inflating bag-valve were provided. The SimBaby is a sophisticated HPS that permits real-time monitoring and recording of simulated physiologic parameters. The participant was instructed to secure the airway and initiate positive pressure ventilation with the bag-valve. The timer started as a blue light around the mouth of the Simbaby was lit, signifying cyanosis. Time to successful ventilation, as detected by the HPS, was recorded. The number of attempts to achieve success was recorded. An additional attempt was defined as when the device lost contact with the HPS. Success was defined when a breath was registered by the HPS. Complications, such as right main-stem intubations, esophageal intubations, and malposition were recorded by sensors on the HPS. The participants were informed whether the esophagus was intubated, and another attempt was made. After the participant successfully secured the airway by using the device, the procedure was repeated by using the alternative device. At the conclusion of the workshop, the participants were asked which of the 2 devices they preferred in pediatric arrests.
On the basis of previous data,6 presuming a 50% difference in times to effective ventilation with each device, to detect a significant difference between the groups with a 2-tailed α value of .05 and power of .90, ∼45 participants were required. The primary outcome was the time from the beginning of the simulation scenario to effective ventilation. The number of attempts with each device was recorded. For each participant, data with the 2 devices were compared by using the paired t test. We also compared the rates of complications (esophageal intubation, right main-stem intubation) of ETTs with LMA (air leak as a result of malposition) by using χ2 analysis.
The study was conducted during a 2-year period from June 2005 to June 2007. All 52 participants who were approached for the study agreed to participate. Their demographics are shown in Table 1. None of the participants had previous experience with LMA use in children, whereas all had experience with ETTs.
During the resuscitation scenarios, the mean ± SD length of time to effective ventilation was 46 ± 32 seconds when using ETTs and 23 ± 21 seconds when using LMA. The mean difference was 23 seconds (95% confidence interval: 13–34 seconds). The mean number of attempts to achieve effective ventilation was 1.27 ± 0.53 when using ETTs and 1.10 ± 0.36 when using LMA (P = .03).
There were 9 (17%) episodes of esophageal intubations and 14 (27%) episodes of right main-stem intubations when using ETTs. There were 5 (9.5%) episodes of air leak as a result of malposition while using LMA during the initial attempt. Total number of misplacement in the ETT group was 34%, compared with 9.5% in the LMA group. This difference was statistically significant (P < .0001). After the course, most (40 of 52) participants preferred LMA to ETTs as the airway device of choice in pediatric arrests.
Our study has several limitations. We used an infant-sized HPS for our study. There are several characteristics of the SimBaby that may not reflect reality. Specifically, the scenarios did not include airway trauma, vomiting, and airway secretions, which often occur in clinical situations. The lack of requirement for direct visualization should confer advantages to LMA in these situations.
The HPS that was used in the study can record only a subset of complications that result from the use of ETTs and LMA. Theoretically, because LMA does not produce a completely air-tight seal, gastric distension, vomiting, and aspiration may be more common in patients with intact airway reflexes, as compared with ETTs. This could not be evaluated with the equipment used in our study. The size of the SimBaby (18-month-old child) may limit the generalizability of our results to older children and adolescents.
Although the participants were blinded to the hypotheses of the study, we did not formally evaluate the effectiveness of the blinding. The HPS was operated by the investigators who were not blinded to the hypotheses. The timing by the HPS, however, was objective and not influenced by the operators.
In this pilot study, we demonstrated significant advantages of LMA over ETTs in pediatric arrest, as performed by prehospital personnel using a high-fidelity HPS. Most children who sustain cardiopulmonary arrests in the prehospital setting experience devastating consequences.2 Few data are available to help identify factors that influence outcome. Because respiratory arrests often precede cardiac arrests in children, it is reasonable to hypothesize that early establishment of effective ventilation and oxygenation may be associated with better outcomes.
Proficiency in airway management in children is difficult to acquire and maintain for prehospital personnel. This is presumably attributable to great variations in the airway anatomy in the pediatric population as well as the relative infrequency with which most prehospital medical personnel encounter pediatric arrests. The optimal procedure to establish effective oxygenation and ventilation in children in the prehospital setting is still to be determined. One study demonstrated a trend for increased return of spontaneous circulation when an ETT was placed.2 Conversely, another study found that the outcome in pediatric arrest was not improved by the use of ETTs, as compared with bag-valve-mask ventilation, yet was potentially associated with more complications.4 Despite a lack of strong evidence for the utility of endotracheal intubation in the prehospital setting in children, it is widely taught to EMS personnel. Because of relative infrequency of pediatric respiratory and cardiac arrest, prehospital personnel are generally poorly trained in performing ETT placement in children. Whatever skills they gain from training usually soon dissipates.10
The LMA is a relatively new airway device. It became commercially available in the United States in 1992. The device consists of a curved plastic tube with an elliptical inflatable mask at 1 end (Fig 1), which is inserted blindly into the posterior pharynx of the patient. The mask is inflated in the hypopharynx, creating an air-tight seal around the upper esophagus.
The device offers the intriguing possibility of rapid establishment of effective ventilation in arrest victims, even when performed by relatively inexperienced personnel. Previous research of adults demonstrated that LMA is superior to ETTs in experimental settings with nonphysician operators.7 To date, few data on the use of LMA in pediatrics exist in the literature. Most of the studies involved isolated case reports8,9 and use of the device in operating suites.11–13 One study assessed the feasibility of mannequin training for LMA placement in neonatal resuscitation.5 One recent study evaluated the feasibility of brief training of prehospital personnel in the use of LMA.14
We undertook this pilot project to study the practicability of using this alternative airway device and compare its use with the current standard, the ETT, with a limited amount of training. In our pilot study involving 52 participants in simulated settings, there were clearly advantages to using LMA in more rapid establishment of effective ventilation and fewer complications, as compared with the use of ETTs. The amount of training required was minimal, consistent with previous data.5,14
On average, the operators were able to place an LMA correctly in half the time that it took to place an ETT. Although the difference of 23 seconds is statistically significant, this may seem to be a relatively small advantage clinically. It must be kept in mind, however, that the simulation scenarios were conducted in well-lit, controlled settings with participants having ready access to equipment of the correct sizes. In real-life situations, multiple decisions need to be made in the selection of appropriate type and size of laryngoscopes and ETTs. With LMA, only 1 piece of equipment needs to be used. These time differences would likely be significantly amplified in actual clinical practice.
There were high numbers of complications while using ETTs. The rate of esophageal intubation at 17%, although high, is in line with previous data.4 Unrecognized esophageal intubation is associated with devastating results. The LMA, by design, is immobilized above the esophagus and therefore has significant advantages in this regard. In our study, malposition of LMA was immediately recognized by the operators and additional attempts were made.
Our study did not evaluate the retention of skills. Studies have shown significant erosion of pediatric knowledge and skills acquired in courses for prehospital providers.10,15 With relatively fewer steps involved in the use of LMA, it is likely that these skills will be better retained. Additional studies to evaluate the retention of LMA skills should be undertaken.
Our data lend support to the use of this device as an alternative in the field for pediatric patients. In simulated pediatric arrests, the use of LMA, as compared with ETT, led to more rapid establishment of effective ventilation and fewer complications, as performed by prehospital providers. Additional studies are needed to establish LMA as a potential first-line device in the prehospital setting.
This study was supported in part by an Ambulatory Pediatric Association Young Investigator grant and Clinical and Translational Science Award KL2 RR024138 from the National Center for Research Resources, a component of the National Institutes of Health, and National Institutes of Health Roadmap for Medical Research.
- Accepted April 9, 2008.
- Address correspondence to Lei Chen, MD, Yale University School of Medicine, Section of Pediatric Emergency Medicine, 840 Howard Ave, New Haven, CT 06504. E-mail:
This study was previously presented in abstract form at the Pediatric Academic Society meeting; May 2, 2006; San Francisco, CA.
The authors have indicated they have no financial relationships relevant to this article to disclose.
What's Known on This Subject
Respiratory and cardiac arrests are rare but devastating occurrences in children. The optimal airway device in the prehospital setting is not well established. The LMA is a relatively new device in pediatrics.
What This Study Adds
In simulated pediatric arrests, the use of LMA resulted in shorter time to effective ventilation and few complications, compared with ETTs, when performed by prehospital personnel.
- Copyright © 2008 by the American Academy of Pediatrics