Controversy surrounds the optimal prehospital management of the pediatric airway. Options include bag-mask ventilation (BMV), endotracheal intubation (ETI), and supraglottic devices, such as the laryngeal mask airway (LMA). However, the clinical effectiveness of these 3 modalities has not been adequately compared within the pediatric population.

Although ETI has been considered the criterion standard for airway management, failure and complications associated with prehospital ETI range from 5% to 50% [[1]x[1]Aijan, P., Tsai, A., Knopp, R., and Kallsen, G.W. Endotracheal intubation of pediatric patients by paramedics. Ann Emerg Med. 1989; 18: 489–494

Abstract | Full Text PDF | PubMed | Scopus (58)See all References, [2]x[2]Katz, S.H. and Falk, J.L. Misplaced endotracheal tubes by paramedics in an urban emergency medical services system. Ann Emerg Med. 2001; 37: 32–37

Abstract | Full Text | Full Text PDF | PubMed | Scopus (367)See all References, [3]x[3]Sayre, M.R., Sakles, J.C., Mistler, A.F., Evans, J.L., Kramer, A.T., and Pancioli, A.M. Field trial of endotracheal intubation by basic EMTs. Ann Emerg Med. 1998; 31: 228–233

Abstract | Full Text | Full Text PDF | PubMed | Scopus (137)See all References, [4]x[4]Bradley, J.S., Billows, G.L., Olinger, M.L., Boha, S.P., Cordell, W.H., and Nelson, D.R. Prehospital oral endotracheal intubation by rural basic emergency medical technicians. Ann Emerg Med. 1998; 32: 26–32

Abstract | Full Text | Full Text PDF | PubMed | Scopus (99)See all References, [5]x[5]Colwell, C.B., McVaney, K.E., Haukoos, J.S., Wiebe, D.P., Gravitz, C.S., Dunn, W.W. et al. An evaluation of out-of-hospital advanced airway management in an urban setting. Acad Emerg Med. 2005; 12: 417–422

CrossRef | PubMedSee all References]. Because ETI is used infrequently in prehospital pediatric resuscitation, it is difficult for Emergency Medical Services (EMS) personnel to maintain this skill [[3]x[3]Sayre, M.R., Sakles, J.C., Mistler, A.F., Evans, J.L., Kramer, A.T., and Pancioli, A.M. Field trial of endotracheal intubation by basic EMTs. Ann Emerg Med. 1998; 31: 228–233

Abstract | Full Text | Full Text PDF | PubMed | Scopus (137)See all References, [6]x[6]Burton, J.H., Bauman, M.R., Maoz, T., Bradshaw, J.R., and Lebrun, J.E. Endotracheal intubation in a rural EMS state: Procedure utilization and impact of skills maintenance guidelines. Prehosp Emerg Care. 2003; 7: 352–356

CrossRef | PubMedSee all References]. In fact, recent literature has questioned the safety and benefit of prehospital intubation in certain patient populations.

In 2000, Gausche et al [7x[7]Gausche, M., Lewis, R.J., Stratton, S.J., Haynes, B.E., Gunter, C.S., Goodrich, S.M. et al. Effect of out-of-hospital pediatric endotracheal intubation on survival and neurologic outcome: a controlled clinical trial. JAMA. 2000; 283: 783–790

CrossRef | PubMedSee all References][7] demonstrated equivocal neurologic outcome and survival to discharge with pediatric mask and endotracheal tube (ETT) ventilation in the prehospital setting. Emphasis has now been placed on providing sustained mask ventilation rather than prehospital ETI in pediatric patients. However, mask ventilation is difficult to sustain for long periods of time, particularly in a moving vehicle [8x[8]Davidovic, L., LaCovey, D., and Pitetti, R.D. Comparison of 1-versus 2-person bag-valve-mask techniques for manikin ventilation of infants and children. Ann Emerg Med. 2005; 46: 37–42

Abstract | Full Text | Full Text PDF | PubMed | Scopus (30)See all References][8].

Laryngeal mask airways are an attractive alternative to both ETI and mask ventilation because they do not require direct visualization, can be placed more quickly than an ETT [[9]x[9]Bosch, J., de Nooij, J., de Visser, M., Cannegieter, S.C., Terpstra, N.J., Heringhaus, C. et al. Prehospital use in emergency patients of a laryngeal mask airway by ambulance paramedics is a safe and effective alternative for endotracheal intubation. Emerg Med J. 2014; : 750–753

CrossRef | PubMed | Scopus (8)See all References, [10]x[10]Ruetzler, K., Gruber, C., Nabecker, S., Wohlfarth, P., Priemayr, A., Frass, M. et al. Hands-off time during insertion of six airway devices during cardiopulmonary resuscitation: a randomized manikin trial. Resuscitation. 2011; 82: 1060–1063

Abstract | Full Text | Full Text PDF | PubMed | Scopus (27)See all References, [11]x[11]Gatward, J.J., Thomas, M.J., Nolan, J.P., and Cook, T.M. Effect of chest compressions on the time taken to insert airway devices in a manikin. Br J Anaesth. 2008; 100: 351–356

CrossRef | PubMed | Scopus (81)See all References, [12]x[12]Hoyle, J.D. Jr., Jones, J.S., Deibel, M., Lock, D.T., and Reischman, D. Comparative study of airway management techniques with restricted access to patient airway. Prehosp Emerg Care. 2007; 11: 330–336

CrossRef | PubMed | Scopus (20)See all References, [13]x[13]Pennant, J.H. and Walker, M.B. Comparison of the endotracheal tube and laryngeal mask in airway management by paramedical personnel. Anesth Analg. 1992; 74: 531–534

CrossRef | PubMedSee all References], and may be easier to maintain than mask ventilation. Laryngeal mask airways have also been placed and used successfully while maintaining inline cervical spine stabilization [14x[14]Matioc, A.A. and Wells, J.A. The LMA-unique in a prehospital trauma patient: interaction with a semirigid cervical collar: a case report. J Trauma. 2002; 52: 162–164

CrossRef | PubMedSee all References][14], in chest compressions [[10]x[10]Ruetzler, K., Gruber, C., Nabecker, S., Wohlfarth, P., Priemayr, A., Frass, M. et al. Hands-off time during insertion of six airway devices during cardiopulmonary resuscitation: a randomized manikin trial. Resuscitation. 2011; 82: 1060–1063

Abstract | Full Text | Full Text PDF | PubMed | Scopus (27)See all References, [11]x[11]Gatward, J.J., Thomas, M.J., Nolan, J.P., and Cook, T.M. Effect of chest compressions on the time taken to insert airway devices in a manikin. Br J Anaesth. 2008; 100: 351–356

CrossRef | PubMed | Scopus (81)See all References], and in situations in which access to the airway is restricted as may occur during extrication after motor vehicle collision [12x[12]Hoyle, J.D. Jr., Jones, J.S., Deibel, M., Lock, D.T., and Reischman, D. Comparative study of airway management techniques with restricted access to patient airway. Prehosp Emerg Care. 2007; 11: 330–336

CrossRef | PubMed | Scopus (20)See all References][12]. Successful utilization of an LMA requires minimal training [[15]x[15]Morse, Z., Sano, K., Kageyama, I., and Kanri, T. The relationship of placement accuracy and insertion times for the laryngeal mask airway to the training of inexperienced dental students. Anesth Prog. 2002; 49: 9–13

PubMedSee all References, [16]x[16]Bickenbach, J., Schalte, G., Beckers, S., Fries, M., Derwall, M., and Rossaint, R. The intuitive use of laryngeal airway tools by first year medical students. BMC Emerg Med. 2009; 9: 18

CrossRef | PubMed | Scopus (15)See all References] and skill retention for LMA placement may also be better than that for ETIs [17x[17]Ruetzler, K., Roessler, B., Potura, L., Priemayr, A., Robak, O., Schuster, E. et al. Performance and skill retention of intubation by paramedics using seven different airway devices--a manikin study. Resuscitation. 2011; 82: 593–597

Abstract | Full Text | Full Text PDF | PubMed | Scopus (34)See all References][17].

Regardless of which advanced airway modality is used, confirmation of proper placement, adequate ventilation, and prompt recognition of device displacement are central to improving outcomes in prehospital pediatric advanced airway management. Pulse oximetry, a noninvasive measurement of arterial blood oxygenation, has become a standard measure of respiratory status in prehospital emergency medicine. However, pulse oximeters require adequate plethysmographic pulsations to distinguish arterial from background venous and tissue light absorption. The plethysmography may be affected by motion, hypothermia, vasoconstriction, and poor perfusion—all common complications during prehospital and emergency department (ED) care [[18]x[18]Trivedi, N., Ghouri, A., Lai, E., Shah, N.K., and Barker, S.J. Pulse oximeter performance during desaturation and resaturation: a comparison of seven models. J Clin Anesth. 1997; 9: 184–188

Abstract | Full Text PDF | PubMed | Scopus (51)See all References, [19]x[19]Silverston, P. Pulse oximetry at the roadside: a study of pulse oximetry in immediate care. BMJ. 1989; 298: 711–713

CrossRef | PubMedSee all References, [20]x[20]Trivedi, N., Ghouri, A., Shah, N., Lai, E., and Barker, S.J. Effects of motion, ambient light, and hypoperfusion on pulse oximeter function. J Clin Anesth. 1997; 9: 179–183

Abstract | Full Text PDF | PubMed | Scopus (68)See all References]. Measurement of carbon dioxide in the exhaled breath (ETCO₂) can be used to confirm both correct airway device placement and effectiveness of assisted ventilation. A prospective study by Silvestri et al found 100% recognition of ETT placement when paramedics used continuous ETCO₂ monitors [21x[21]Silvestri, S., Ralls, G.A., Krauss, B., Thundivil, J., Rothrock, S.G., Senn, A. et al. The effectiveness of out-of-hospital use of continuous end-tidal carbon dioxide monitoring on the rate of unrecognized misplaced intubation within a regional emergency medical services system. Ann Emerg Med. 2005; 45: 497–503

Abstract | Full Text | Full Text PDF | PubMed | Scopus (118)See all References][21]. Without the use of ETCO₂ monitors, 23% of misplaced ETTs went unrecognized. Attention and response to continuous ETCO₂ monitoring can also prevent hyper- and hypoventilation [22x[22]Helm, M., Schuster, R., Hauke, J., and Lampl, L. Tight control of prehospital ventilation by capnography in major trauma victims. Br J Anaesth. 2003; 90: 327–332

CrossRef | PubMed | Scopus (66)See all References][22], which has been shown to improve neurologic outcomes [23x[23]Davis, D.P., Dunford, J.V., Ochs, M., Park, K., and Hoyt, D.B. The use of quantitative end-tidal capnometry to avoid inadvertent severe hyperventilation in patients with head injury after paramedic rapid sequence intubation. J Trauma. 2004; 56: 808–814

CrossRef | PubMedSee all References][23].

Colorimetric ETCO₂ detectors are now routinely used to detect proper initial placement of ETTs in pediatric patients [24x[24]Kelly, J.S., Wilhoit, R.D., Brown, R.E., and James, R. Efficacy of the FEF Colorimetric end-tidal carbon dioxide detector in children. Anesth Analg. 1992; 75: 45–50

PubMedSee all References][24]. More advanced electronic capnometers display a single numerical value of detected ETCO₂ with each cycle of ventilation. “Capnography,” in contrast to “capnometry,” displays carbon dioxide levels over time. The terms capnogram and capnograph refer to the pictorial waveform associated with the ETCO₂ concentration as it changes throughout the respiratory cycle. Capnography has been shown to improve time to detection and correction of ETT dislodgement among paramedics and pediatric residents after minimal capnography training [[25]x[25]Langhan, M.L., Ching, K., Northrup, V., Alletag, M., Kadia, P., Santucci, K. et al. A randomized controlled trial of capnography in the correction of simulated endotracheal tube dislodgement. Acad Emerg Med. 2011; 18: 590–596

CrossRef | PubMed | Scopus (8)See all References, [26]x[26]Langhan, M.L., Auerbach, M., Smith, A.N., and Chen, L. Improving detection by pediatric residents of endotracheal tube dislodgement with capnography: a randomized controlled trial. J Pediatr. 2012; 160: 1009–1014

Abstract | Full Text | Full Text PDF | PubMed | Scopus (3)See all References]. Handheld capnometers have been shown to be effective in the prehospital setting in pediatric patients who undergo ETI [27x[27]Singh, S., Allen, W.D., Venkataraman, S.T., and Bhende, M.S. Utility of a novel quantitative handheld microstream capnometer during transport of critically ill children. Am J Emerg Med. 2006; 24: 302–307

Abstract | Full Text | Full Text PDF | PubMed | Scopus (21)See all References][27], and ETCO₂ values have been demonstrated during ETT and LMA ventilation [[28]x[28]Chhibber, A.K., Kolano, J.W., and Roberts, W. Relationship between end-tidal and arterial carbon dioxide with laryngeal mask airways and endotracheal tubes in children. Anesth Analg. 1996; 82: 247–526

PubMedSee all References, [29]x[29]Chhibber, A.K., Fickling, K., Kolano, J.W., and Roberts, W.A. Comparison of end-tidal and arterial carbon dioxide in infants using laryngeal mask airway and endotracheal tube. Anesth Analg. 1997; 84: 51–53

PubMedSee all References]. However, the continuous capnograph has not been studied with LMA or mask ventilation in the pediatric population.

The aim of this study is to describe capnographs obtained during effective ventilation of pediatric patients with a mask, ETT, and LMA. We hypothesized that the capnographs obtained with each of these modalities would be indistinguishable and that capnography could therefore be used to guide ventilation of pediatric patients, regardless of the airway modality used.

A total of 116 capnographs were captured in 29 patients. Fifty-five percent (16/29) received ETT ventilation and 45% (13/29) received LMA ventilation as their definitive airway. The median age for all patients enrolled was 4.5 years (2 months to 16.8 years), and the median weight was 15.3 kg (6.3-69.2 kg). Table 1Table 1 shows the demographics data arranged by advanced airway type. All study participants received ventilation with both bag types. Fig. 2Fig. 2 shows the weight distribution of our subjects based on LMA size.

Both anesthesiologists reviewed 107 of 116 (92.2%) capnographs. However, 9 of 116 (7.8%) were reviewed by only 1 anesthesiologist secondary to human error (pages unintentionally skipped by reviewer). Reviewers were unavailable for a secondary review. Table 2Table 2 depicts the ventilation ratings provided by each reviewer. Eighty-eight percent (196/223) of the capnographs were rated as “Some” or “Adequate Ventilation,” whereas 12% (27/223) were found to be “Inadequate.” Both anesthesiologists agreed on the adequacy of ventilation 77% of the time with a κ of 0.6 (P < .001). Reasons for “Inadequate” ventilation ratings were only provided in 7 cases. Five major categories of issues were identified: infrequent ventilation, incomplete ventilation, prolonged expiratory phase, obstruction, and inconsistent ventilation. More than one reason for “Inadequate” ventilation was listed in several capnographs. In 2 cases, the reviewer commented on issues in only part of the capnograph (the last breath, for example) that made them concerned that this type of ventilation was not sustainable if continued in this particular manner. Infrequency of ventilation and prolonged expiratory phase were the most common concerns identified. Too few comments were provided to enable meaningful statistical analysis.

We then compared the ventilation ratings as a function of airway modality (Fig. 3Fig. 3). Reviewer 1 was 4.5 times (0.6, 34) and reviewer 2 was 8.6 times (1.2, 62) more likely to rate mask ventilation as inadequate compared to the criterion-standard ETT. There was no appreciable difference noted between the ETT and LMA ratings, with the majority (78% and 88%, respectively) receiving an “Adequate” rating. There was greater variability in ventilation rating among the mask group in comparison to the ETT and LMA groups (45% Adequate, 34% Some Ventilation, 21% Inadequate). The mask capnographs were further analyzed by bag type (Fig. 4Fig. 4). No significant difference in evaluator ratings was appreciated between FI and SI bags.

Both reviewers had difficulty identifying which airway was used for each capnograph (Table 3Table 3). Both reviewers were better able to identify mask vs the ETT or LMA, but were still only able to do so 12.8%(14/109) (reviewer 1) and 21.1% (24/114) (reviewer 2) of the time. Reviewer 1 was more likely to choose “unsure,” selecting this answer 72% (83/109) of the time for the airway modality and 88% (102/109) of the time for the bag type. Reviewer 2 chose “unsure” only 1% (1/114) and 6% (7/114) of the time, respectively. Neither reviewer was able to differentiate between FI and SI bag type.

Finally, we chose to categorize our results in terms relevant to prehospital resuscitation and transport medicine. We therefore considered ratings of “Adequate” and “Some” ventilation to be clinically similar and significant in comparison to “Inadequate” ventilation ratings. Results were combined into “Good” (Adequate + Some ventilation) and “Poor” (Inadequate ventilation) dichotomous variables for subanalysis. In the ETT group, 97% (58/60) received a “Good” rating. In the LMA group, 98% (50/51) received a “Good” rating. Lastly, 79% (88/112) of the mask group capnographs were rated as “Good.”

Previous capnography studies that compare airway modalities describe quantitative numerical ETCO₂ data and have focused primarily on ETT and LMAs. This study is the first to describe capnographs for mask ventilation and the first to compare capnographs for these 3 airway modalities in the pediatric population. These data show not only that capnographs can be generated during mask ventilation but also that they are also similar enough in shape to those produced with ETT- or LMA-assisted ventilation to make them generally indiscernible to even a highly trained individual.

It remains unclear whether mask ventilation itself provides less optimal ventilation or whether capnography is a suboptimal measure of ventilation during mask ventilation. Numerical ETCO₂ and pulse oximetry data were analyzed as an additional measure of ventilation. Because the initial values of each of these data points were likely to reflect ventilation before the data measurement period, the change in ETCO₂ and pulse oximetry was calculated. Two capnographs with missing data points were excluded. The median change in ETCO₂ was 1 (IQ [Interquartile Range]−3, +3). The median change in pulse oximetry was 0 (IQ 0, 0). Both were similar for both the mask and the advanced airway groups; however, the time between these data points is too small to accurately detect a trend. Tidal volumes and peak pressure data were not useful for 2 reasons: they were not measureable when the SI bag was in use, and each of these measurements is related to a single ventilatory cycle, rather than continuous ventilation, and may vary widely within the time that the capnograph is generated, making 2 discrete measurements irrelevant. Ultimately, we hypothesize that slight changes in the position of the providers’ hands and mask seal on the subject’s face may not allow for absolute consistency in capnograph tracings and may offer some explanation for the poorer rating of the mask capnographs compared with the advanced airway capnographs. However, the clinical relevance of these subtle differences remains to be determined. Continuous ETCO₂ or arterial CO₂ measurement over a longer period of continuous ventilation with these airway modalities will be necessary to answer this question.

Despite the fact that our anesthesiologist reviewers were more likely to rate the mask ventilation capnographs poorly, they were unable to discern the airway type. We suspect that reviewer fatigue may have played a role in this result. Airway-type recognition may have been more definitive if reviewers were unable to opt for “unsure.”

Although all capnographs were generated during actual patient ventilations performed by a board-certified pediatric anesthesiologist and determined to be adequate in the moment, some of the capnographs were subsequently deemed as “Inadequate” ventilation by our similarly trained reviewers, regardless of type of airway or ventilation modality used. Truncated capnograph segments represent only a limited window into the overall care of the patient. Dynamic processes (such as adjustments in patient tidal volume, management of supraglottic airway obstruction, depth of anesthesia, manual excursion of gastric air, or provider response to other available patient data such as electrocardiogram and plethysmography) cannot adequately be appreciated during a limited recording. Secondly, interpretations made upon isolated, post hoc review may differ from those made in real time with a patient. For example, the comment “Prolonged expiratory phase” was associated with some of the capnographs rated as “Inadequate.” A prolonged expiratory phase may indicate a primary pulmonary problem, such as bronchospasm, vs ETT obstruction. The treating anesthesiologist can differentiate between these etiologies based upon medical history and assessment of the patient, whereas the reviewer cannot.

Our study results suggest that continuous capnograph waveforms may be clinically useful for the assessment of pediatric ventilation, regardless of airway type. As the literature supports the benefits of prehospital mask ventilation over ETI in the prehospital setting, utilization of a continuous capnograph may be a critical tool to ensure adequate ventilation. Bag-mask ventilation is often underappreciated in its difficulty. Mask seal, adequate chest rise, and breath sounds are significantly more difficult to assess in the prehospital setting, as providers are challenged with multiple tasks, continuous movement in the ambulance, environmental factors, and limited space. The use of continuous capnography allows actual evaluation of dynamic gas exchange that other surrogate clinical markers only suggest. Capnography may also be useful after only minimal training. Langhan et al [26x[26]Langhan, M.L., Auerbach, M., Smith, A.N., and Chen, L. Improving detection by pediatric residents of endotracheal tube dislodgement with capnography: a randomized controlled trial. J Pediatr. 2012; 160: 1009–1014

Abstract | Full Text | Full Text PDF | PubMed | Scopus (3)See all References][26] showed faster detection of ETT dislodgement by pediatric residents after less than 1 hour of didactic capnography education. We anticipate that familiarity with capnographs will improve recognition of airway device misplacement or displacement and will allow EMS providers, as well as in-hospital physicians and trainees, to administer more effective ventilations in the pediatric population, particularly during patient transport.

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.