A field comparison of the pharyngeotracheal lumen airway and the endotracheal tube

Prehospital Airway Management: A Systematic Review

Objective: To assess comparative benefits and harms across three airway management approaches (bag valve mask [BVM], supraglottic airway [SGA], and endotracheal intubation [ETI]) used by prehospital emergency medical services (EMS) to treat patients with trauma, cardiac arrest, or medical emergencies, and how they differ based on techniques and devices, EMS personnel and patient characteristics. Data sources: We searched electronic citation databases (Ovid® MEDLINE®, CINAHL®, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, and Scopus®) from 1990 to September 2020. Review methods: We followed Agency for Healthcare Research and Quality Effective Health Care Program Methods guidance. Outcomes included mortality, neurological function, return of spontaneous circulation (ROSC), and successful advanced airway insertion. Meta-analyses using profile-likelihood random effects models were conducted, with analyses stratified by study design, emergency type, and age. Results: We included 99 studies involving 630,397 patients. We found few differences in primary outcomes across airway management approaches. For survival, there was no difference for BVM versus ETI or SGA in adult and pediatric patients with cardiac arrest or trauma. For neurological function, there was no difference for BVM versus ETI and SGA versus ETI in pediatric patients with cardiac arrest. There was no difference in BVM versus ETI in adults with cardiac arrest, but improved neurological function with BVM or ETI versus SGA. There was no difference in ROSC for patients with cardiac arrest for BVM versus ETI or SGA in adults and pediatrics, or SGA versus ETI in pediatrics. There was higher frequency of ROSC in adults with SGA versus ETI. For successful advanced airway insertion, there was higher first-pass success with SGA versus ETI for all patients except adult medical patients (no difference), and no difference in overall success using SGA versus ETI in adults. Conclusions: The currently available evidence does not indicate benefits of more invasive airway approaches based on survival, neurological function, ROSC, or successful airway insertion. Strength of evidence was low or moderate; most included studies were observational. This supports the need for high-quality randomized controlled trials to advance clinical practice and EMS education and policy, and improve patient-centered outcomes.

Comparison of tracheal intubation and alternative airway techniques performed in the prehospital setting by paramedics: a systematic review

This systematic review included controlled clinical trials comparing tracheal intubation (TI) with alternative airway techniques (AAT) (bag-mask ventilation and use of extraglottic devices) performed by paramedics in the prehospital setting. A priori outcomes to be assessed were survival, neurologic outcome, airway management success rates and complications. We identified trials using EMBASE, MEDLINE, CINAHL, The Cochrane Library, Web of Science, author contacts and hand searching. We included 5 trials enrolling a total of 1559 patients. No individual study showed any statistical difference in outcomes between the TI and AAT groups. Because of study heterogeneity, we did not pool the data. This is the most comprehensive review to date on paramedic trials. Owing to the heterogeneity of prehospital systems, administrators of each system must individually consider their airway management protocols.

A meta-analysis of prehospital airway control techniques part II: alternative airway devices and cricothyrotomy success rates

BACKGROUND

Airway management is a key component of prehospital care for seriously ill and injured patients. Oral endotracheal intubation (OETI) is the definitive airway of choice in most emergency medical services (EMS) systems. However, OETI may not be an approved skill for some clinicians or may prove problematic in certain patients because of anatomic abnormalities, trauma, or inadequate relaxation. In these situations alternative airways are frequently employed. However, the reported success rates for these devices vary widely, and established benchmarks are lacking.

OBJECTIVE

We sought to determine pooled estimates of the success rates of alternative airway devices (AADs) and needle cricothyrotomy (NCRIC) and surgical cricothyrotomy (SCRIC) placement through a meta-analysis of the literature.

METHODS

We performed a systematic literature search for all English-language articles reporting success rates for AADs, SCRIC, and NCRIC. Studies of field procedures performed by prehospital personnel from any nation were included. All titles were reviewed independently by two authors using prespecified inclusion criteria. Pooled estimates of success rates for each airway technique were calculated using a random-effects meta-analysis model.

RESULTS

Of 2,005 prehospital airway titles identified, 35 unique studies were retained for analysis of AAD success rates, encompassing a total of 10,172 prehospital patients. The success rates for SCRIC and NCRIC were analyzed across an additional 21 studies totaling 512 patients. The pooled estimates (and 95% confidence intervals [CIs]) for intervention success across all clinicians and patients were as follows: esophageal obturator airway-esophageal gastric tube airway (EOA-EGTA) 92.6% (90.1%-94.5%); pharyngeotracheal lumen airway (PTLA) 82.1% (74.0%-88.0%); esophageal-tracheal Combitube (ETC) 85.4% (77.3%-91.0%); laryngeal mask airway (LMA) 87.4% (79.0%-92.8%); King Laryngeal Tube airway (King LT) 96.5% (71.2%-99.7%); NCRIC 65.8% (42.3%-83.59%); and SCRIC 90.5% (84.8%-94.2%).

CONCLUSIONS

We provide pooled estimates for prehospital AAD, NCRIC, and SCRIC airway interventions. Of the AADs, the King LT demonstrated the highest insertion success rate (96.5%), although this estimate is based on limited data, and data regarding its ventilatory effectiveness are lacking; more data are available for the ETC and LMA. The ETC, LMA, and PTLA all had similar-but lower-success rates (82.1%-87.4%). NCRIC has a low rate of success (65.8%); SCRIC has a much higher success rate (90.5%) and should be considered the preferred percutaneous rescue airway.

Advances in airway management

Emergency ventilation is an essential component of basic life support. Respiratory emergencies occur far more frequently than cardiac arrest and, if not treated promptly and effectively, may lead to cardiac arrest. Many respiratory emergencies require assisted ventilation to prevent the occurrence of hypoxemia, hypercarbia, and cardiac decompensation. Emergency assisted ventilation is often difficult to perform and is associated with several adverse complications, such as gastric inflation, regurgitation, and pulmonary aspiration. The American Heart Association sponsored conferences in 1999 and 2000 to review and revise guidelines for cardiopulmonary resuscitation. This article reviews the science behind guideline changes related to pulmonary resuscitation and discusses recent advances in emergency airway management, focusing on noninvasive techniques for ventilation (mouth-to-mouth ventilation, bag-mask ventilation) and alternative airway devices (laryngeal mask airway, the Combitube).

Airway and ventilation management

Airway management is fundamental to ACLS. Success with any airway device relies as much on the operator's experience and skill as on the device itself. The purpose of using an airway device is to provide a patent route for ventilating the lungs and to protect against pulmonary aspiration. Training should emphasize the importance of confirming that the airway device is positioned correctly and that the lungs can be ventilated effectively. If airway intervention is to have a positive effect on outcome, the choice of airway device is less important than thorough training, ongoing experience and review, and close attention to complications. Regardless of whether a provider chooses to use the LMA, the combitube, or the tracheal tube, providers must be familiar with more than one method of airway management because of the possibility of failure to insert or ventilate with their primary airway device of choice.

Use of the esophageal tracheal combitube by basic emergency medical technicians

The most appropriate airway device for use in EMS systems staffed by basic skilled EMTs with (EMT-Ds) or without (EMT-Bs) defibrillation capabilities is still a matter of debate. The purpose of this study was to assess the feasibility, safety and effectiveness of the Esophageal Tracheal Combitube (ETC) when used by EMT-Ds in cardiorespiratory arrest patients of all etiologies. The EMTs had automatic external defibrillator (AED) training but no prior advanced airway technique skills. The prehospital intervention was reviewed using the EMTs cardiac arrest report, the AED tape recording of the event and the assessment of the receiving emergency physician. The patients' hospital records and autopsy report were reviewed in search of complications. Eight hundred and thirty-one adult cardiac arrest patients were studied. Placement was successful in 725 (95.4%) of the 760 patients where it was attempted and ventilation was successful in 695 (91.4%). Immediate complications encountered, but not necessarily related to the use of the ETC, were; subcutaneous emphysema (18), tension pneumothorax (5), blood in the oropharynx (15), and swelling of the pharynx (three). An autopsy was done in 133 patients; no esophageal lesions or significant injury to the airway structures were observed. Our results suggest that EMT-Ds can use the ETC for control of the airway and ventilation in cardiorespiratory arrest patients safely and effectively.

Failed rapid sequence intubation in trauma patients: esophageal tracheal combitube is a useful adjunct

OBJECTIVE

To characterize the use of the esophageal tracheal combitube (ETC) in trauma patients who fail orotracheal rapid sequence intubation (RSI).

DESIGN

Prospective protocol design and retrospective chart review.

MATERIALS AND METHODS

Flight nurses were trained in the use of the ETC by mannequin simulation, videotape review, and didactic sessions. ETC insertion was attempted after failure of two or more attempts at orotracheal RSI. Over a 12-month period, 12 patients had ETC insertion, and 10 cases qualified for review. Injuries, number of failed orotracheal RSI attempts, definitive airway, initial arterial blood gas results, and outcome were recorded.

RESULTS

ETC insertion was successful in all 10 patients in whom it was attempted. Definitive airway control was achieved by conversion to orotracheal intubation in seven patients, emergency department cricothyroidotomy in one patient, and operative room tracheostomy in two patients. No patient died because of failure to control the airway. Seven patients requiring ETC had mandible fractures.

CONCLUSION

ETC insertion is an effective method of airway control in trauma patients who fail orotracheal RSI. It may be particularly useful in the patient with maxillofacial trauma and offers a practical alternative to surgical cricothyroidotomy in difficult airway situations.

The PTL, Combitube, laryngeal mask, and oral airway: a randomized prehospital comparative study of ventilatory device effectiveness and cost-effectiveness in 470 cases of cardiorespiratory arrest

PURPOSE

A prehospital study was conducted to assess and compare three alternative airway devices and the oral airway for use by non-Advanced Life Support emergency medical assistants (EMAs).

METHOD

A modified randomized crossover design was used. The Pharyngeal Tracheal Lumen Airway (PTL), the laryngeal mask (LM), and the esophageal tracheal Combitube (Combi) were compared objectively for success of insertion, ventilation, and arterial blood gas and spirometry measurements performed upon hospital arrival. Subjective assessment was carried out by EMAs and receiving physicians at the time of device use, and an eight-question comparative evaluation of all devices was completed by EMAs at study conclusion. A comparative cost analysis was performed. Operating room training was compared with mannequin training for the LM. Autopsy findings and survival to hospital discharge were analyzed. The study took place in four non-ALS communities over four and a half years, and involved 470 patients in cardiac and/or respiratory arrest. EMAs had automatic external defibrillator training but no endotracheal intubation skills.

RESULTS

Successful insertion and ventilation: Combi, 86%; PTL, 82%; LM, 73% (p = 0.048). No significant difference was found for objective measurements of ventilatory effectiveness (ABGs and spirometry). Significant comparative differences in subjective evaluation were found.

CONCLUSIONS

The PTL, LM, and Combi appear to offer substantial advances over the OA/BVM system. Although the most costly, the Combitube was associated with the least problems with ventilation and was the most preferred by a majority of EMAs.

Reporting approval by research ethics committees and subjects' consent in human resuscitation research

OBJECTIVE

To determine how frequently reports of research in human cardiopulmonary resuscitation mention approval by a research ethics committee and address subjects' consent.

METHODS

Retrospective review of published reports of interventional research in human cardiopulmonary resuscitation. Reports were retrieved from the MEDLINE database and selected according to pre-established criteria. Data were abstracted independently by the two authors with differences resolved by mutual agreement. Results were analyzed according to whether the research took place in the prehospital setting, the emergency department, or the hospital; whether it was conducted within or outside the United States; whether it received any funding from the US government; its randomization scheme; the year of publication; and whether the journal's instructions required mention of REC approval or subjects' consent.

RESULTS

Reports of 47 studies met our criteria for inclusion. Of these, 24 (51%) mentioned approval by a research ethics committee and 12 (26%) addressed subjects' consent. Significantly more studies reported ethics committee approval or addressed consent during more recent years. Authors were more likely to report consent, REC approval, or both when journal instructions required that REC approval be mentioned.

CONCLUSION

Reports of resuscitation research have not consistently mentioned approval from a research ethics committee or addressed subjects' consent for interventional studies using human subjects. However, they are doing so more frequently in recent years as journal requirements for reporting change. REC approval is now almost always being reported, but subjects' consent is often not addressed. Journal editors and reviewers should ensure that authors adhere to the journal's instructions about reporting ethical conduct of experiments.

Factors influencing successful intubation in the prehospital setting

OBJECTIVE

To explore the determinants influencing oral/nasal endotracheal intubation (OETI/NETI) and determine which cognitive, therapeutic, and technical interventions may assist prehospital airway management.

DESIGN, SETTING, AND PARTICIPANTS

Prospective review of run reports and structured interviews of paramedics involved in OETI/NETI attempts were conducted in a high-volume, inner-city, advanced life support (ALS) system during an eight-month period (July 1991 to February 1992). Data were abstracted from run reports, and paramedics were asked in structured interviews to describe difficulties in OETI/NETI attempts.

RESULTS

Of 236 patients studied, 88% (208) were intubated successfully. Success/failure rate was not related statistically to patients' ages (p = 0.78), medical or trauma complaint (89% vs 85%, p = 0.35), oral versus nasal route (88% vs 85%, p = 0.38), care time (scene+transport times: success, 18 minutes; failure, 20 minutes, p = 0.30), paramedic seniority (p = 0.13), or number of attempts per paramedic (p > 0.05). Increased level of consciousness (LOC) was associated with decreased success rate (p = 0.04). Paramedics reported difficulties in endotracheal intubation (ETI) attempts in 110 (46.6%) of patients. Factors reported to increase ETI difficulty were: 1) technical problems (35.6%); 2) mechanical problems (15.6%); and 3) combative patients (12.7%).

CONCLUSIONS

Oral endotracheal intubation and NETI success rates identified in this study are similar to those described in the literature, although innovative strategies could be used to facilitate prehospital airway management. Many of the factors found to increase ETI difficulty could be ameliorated by the administration of paralytic agents, that is, for combative patients. Focused training in cadaver and animal labs coupled with recurrence training in the operating suites should be used on a regular basis to decrease difficulties in visualization. Interventions directed at alleviating mechanical difficulties that should be explored include new-to-the-field techniques, such as retrograde intubation, fiber-optic technology, and surgical tracheal access.

Teaching basic EMTs endotracheal intubation: can basic EMTs discriminate between endotracheal and esophageal intubation?

HYPOTHESIS

Advanced airway intervention techniques are being considered for use by basic emergency medical technicians (EMTs). It was hypothesized that basic EMTs would be able to discriminate reliably between intratracheal and esophageal endotracheal tube placement in a mannequin model.

DESIGN

An airway mannequin with a closed chest cavity was intubated randomly either esophageally or tracheally, and the cuff was inflated. A stethoscope, bag ventilator, and laryngoscope were available next to the mannequin. Placement was assessed by auscultation or direct visualization at the discretion of the EMT. A blinded investigator graded the student.

SETTING

A classroom in a large, urban medical center.

PARTICIPANTS

Subjects were basic EMTs who volunteered to take part after the conclusion of a six-hour endotracheal intubation training course.

RESULTS

Thirty-three subjects were tested. Seventeen of 18 (94%) tracheal intubations and 11 of 15 (73%) esophageal intubations were identified correctly. Only 72% of the students listened to the epigastrium, 81% listened to the lungs, and 85% attempted ventilation. The 10 students who visualized the cords discovered all five esophageal intubations. The 23 students who did not visualize the cords missed four and found six esophageal intubations.

CONCLUSION

Basic EMTs had difficulty assessing endotracheal tube placement in a mannequin model. The 27% miss rate for identifying esophageal intubations suggests that basic EMTs will require additional training for safe field use of any airway that requires assessment of tube placement.

Invasive airway techniques in resuscitation

Although endotracheal intubation is still the most definitive technique for airway management in patients with cardiac or respiratory arrest, in some emergency care systems, use of endotracheal intubation by prehospital care personnel has been restricted by policy or statute. Therefore, alternative airway devices have been developed. These alternative airway devices include the Esophageal Obturator Airway (EOA) and Esophageal Gastric Tube Airway (EGTA), the Pharyngeotracheal Lumen Airway (PTL), and the Esophageal-Tracheal Combitube (ETC). By examining the available literature concerning these alternative airway devices, we sought to determine 1) if these devices are superior to basic, noninvasive airway techniques (eg, bag-valve-mask ventilation); 2) if they are comparable to endotracheal intubation in terms of ventilation, oxygenation, and potential complications; 3) what the role of these devices should be in prehospital care; and 4) what the best recommendations should be regarding these devices in terms of resuscitation training and future areas for research. The review involved a total of 837 EOA/EGTA, 304 PTL, and 159 ETC study patients. Although ventilation and oxygenation can, in some circumstances, be as good with the EOA/EGTA devices as it is with the endotracheal intubation, in some cases they can be inadequate, and the complication rate is relatively high. Preliminarily, the PTL and the ETC seem to provide adequate ventilation and oxygenation with few complications. However, for both devices, published clinical experience, especially in the prehospital setting, is still limited. Therefore, their use should be left to the discretion of accountable physician directors of applicable resuscitation teams. Regardless of the device used, recognition of proper placement remains the most important aspect of using any invasive airway device. Therefore, proper training and expert medical supervision probably have more influence on the successful use and impact of these devices than any other factors related to the devices themselves. Future training efforts would be most useful if directed at proper endotracheal intubation training and development of improved basic ventilatory skills. Nevertheless, additional controlled, direct-comparison studies of the PTL and ETC devices are recommended and should be conducted in properly supervised emergency medical services systems.