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

An Algorithmic Approach to Prehospital Airway Management

Airway management, including endotracheal intubation, is considered one of the most important aspects of prehospital medical care. This concept paper proposes a systematic algorithm for performing prehospital airway management. The algorithm may be valuable as a tool for ensuring patient safety and reducing errors as well as for training rescuers in airway management.

Emergency airway management in critically injured patients: a survey of U.S. aero-medical transport programs

OBJECTIVE

Pre-hospital airway management represents the intervention most likely to impact outcomes in critically injured patients. As such, airway management issues dominate quality improvement (QI) reviews of aero-medical programs. The purpose of this study was to evaluate current practice patterns of airway management in trauma among U.S. aero-medical service (AMS) programs.

METHODS

The Association of Air Medical Services (AAMS) Resource Guide from 2005 to 2006 was utilized to identify the e-mail addresses of all directors of U.S. aero-medical transport programs. Program directors from 182 U.S. aero-medical programs were asked to participate in an anonymous, web-based survey of emergency airway management protocols and practices. Non-responders to the initial request were contacted a second time by e-mail.

RESULTS

89 programs responded. 98.9% have rapid sequence intubation (RSI) protocols. 90% use succinylcholine, 70% use long-acting neuromuscular blockers (NMB) within their RSI protocol. 77% have protocols for mandatory in-flight sedation but only 13% have similar protocols for maintenance paralytics. 60% administer long-acting NMB immediately after RSI, 13% after confirmation of neurological activity. Given clinical scenarios, however, 97% administer long-acting NMB to patients with scene and in-flight Glasgow Coma Scale (GCS) of 3, even for brief transport times.

CONCLUSIONS

The majority of AMS programs have well defined RSI and in-flight sedation protocols, while protocols for in-flight NMB are uncommon. Despite this, nearly all programs administer long-acting NMB following RSI, irrespective of GCS or flight time. Given the impact of in-flight NMB on initial assessment, early intervention, and injury severity scoring, a critical appraisal of current AMS airway management practices appears warranted.

Airway management for the uninitiated

The 21(st) century has witnessed burgeoning interest in airway management. Pertinent basic sciences are covered in numerous texts and lectures. This article presents clinical information required to perform airway management. It serves as a primer for those interested in learning airway management skills. It does not replace extensive practice under the tutelage of expert airway managers.

The difficult airway in adult critical care

INTRODUCTION

The difficult airway is a common problem in adult critical care patients. However, the challenge is not just the establishment of a safe airway, but also maintaining that safety over days, weeks, or longer.

AIMS

This review considers the management of the difficult airway in the adult critical care environment. Central themes are the recognition of the potentially difficult airway and the necessary preparation for (and management of) difficult intubation and extubation. Problems associated with tracheostomy tubes and tube displacement are also discussed.

RESULTS

All patients in critical care should initially be viewed as having a potentially difficult airway. They also have less physiological reserve than patients undergoing airway interventions in association with elective surgery. Making the critical care environment as conducive to difficult airway management as the operating room requires planning and teamwork. Extubation of the difficult airway should always be viewed as a potentially difficult reintubation. Tube displacement or obstruction should be strongly suspected in situations of new-onset difficult ventilation.

CONCLUSIONS

Critical care physicians are presented with a significant number of difficult airway problems both during the insertion and removal of the airway. Critical care physicians need to be familiar with the difficult airway algorithms and have skill with relevant airway adjuncts.

Emergency intubation for acutely ill and injured patients

BACKGROUND

Emergency intubation has been widely advocated as a life saving procedure in severe acute illness and injury associated with real or potential compromises to the patient's airway and ventilation. However, some initial data have suggested a lack of observed benefit.

OBJECTIVES

To determine in acutely ill and injured patients who have real or anticipated problems in maintaining an adequate airway whether emergency endotracheal intubation, as opposed to other airway management techniques, improves the outcome in terms of survival, degree of disability at discharge or length of stay and complications occurring in hospital.

SEARCH STRATEGY

We searched the Cochrane Injuries Group Specialised Register (December 2006), Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2006, Issue 4), MEDLINE (1950 to November 2006), EMBASE (1980 to week 50, December 2006), National Research Register (Issue 4, 2006), CINAHL (1980 to December 2006), BIDS (to December 2006) and ICNARC (to December 2006). We also examined reference lists of articles for relevant material and contacted experts in the field. Non-English language publications were searched for and examined.

SELECTION CRITERIA

All randomised (RCTs) or controlled clinical trials involving the emergency use of endotracheal intubation in the injured or acutely ill patient were examined.

DATA COLLECTION AND ANALYSIS

The full texts of 452 studies were reviewed independently by two authors using a standard form. Where the review authors felt a study may be relevant for inclusion in the final review or disagreed, the authors examined the study and a collective decision was made regarding its inclusion or exclusion from the review. The results were not combined in a meta-analysis due to the heterogeneity of patients, practitioners and alternatives to intubation that were used.

MAIN RESULTS

We identified three eligible RCTs carried out in urban environments. Two trials involved adults with non-traumatic out-of-hospital cardiac arrest. One of these trials found a non-significant survival disadvantage in patients randomised to receive a physician-operated intubation versus a combi-tube (RR 0.44, 95% CI 0.09 to 1.99). The second trial detected a non-significant survival disadvantage in patients randomised to paramedic intubation versus an oesophageal gastric airway (RR 0.86, 95% CI 0.39 to 1.90). The third included study was a trial of children requiring airway intervention in the prehospital environment. The results indicated no difference in survival (OR 0.82, 95% CI 0.61 to 1.11) or neurologic outcome (OR 0.87, 95% CI 0.62 to 1.22) between paramedic intubation versus bag-valve-mask ventilation and later hospital intubation by emergency physicians; however, only 42% of the children randomised to paramedic endotracheal intubation actually received it.

AUTHORS' CONCLUSIONS

The efficacy of emergency intubation as currently practised has not been rigorously studied. The skill level of the operator may be key in determining efficacy. In non-traumatic cardiac arrest, it is unlikely that intubation carries the same life saving benefit as early defibrillation and bystander cardiopulmonary resuscitation (CPR). In trauma and paediatric patients, the current evidence base provides no imperative to extend the practice of prehospital intubation in urban systems. It would be ethical and pertinent to initiate a large, high quality randomised trial comparing the efficacy of competently practised emergency intubation with basic bag-valve-mask manoeuvres (BVM) in urban adult out-of-hospital non-traumatic cardiac arrest.

A comparison of seal in seven supraglottic airway devices using a cadaver model of elevated esophageal pressure

BACKGROUND

Supraglottic airway devices are increasingly important in clinical anesthesia and prehospital emergency medicine, but there are only few data to assess the risk for aspiration. We designed this study to compare the seal of seven supraglottic airway devices in a cadaver model of elevated esophageal pressure.

METHODS

The classic laryngeal mask airway, laryngeal mask airway ProSeal, intubating laryngeal mask airway Fastrach, laryngeal tube, laryngeal tube LTS II, Combitube, and Easytube were inserted into unfixed human cadavers with an exposed esophagus that had been connected to a water column of 130 cm height. Slow and fast increases of esophageal pressure were performed and the water pressure at which leakage appeared was registered.

RESULTS

The Combitube, Easytube, and intubating laryngeal mask Fastrach withstood the water pressure up to more than 120 cm H2O. The laryngeal mask airway ProSeal, laryngeal tube, and laryngeal tube LTS II were able to block the esophagus until 72-82 cm H2O. The classic laryngeal mask airway showed leakage at 48 cm H2O, but only minor leakage was found in the trachea. Devices with an additional esophageal drain tube drained fluid sufficiently without pulmonary aspiration.

CONCLUSIONS

Concerning the risk of aspiration, the use of devices with an additional esophageal drainage lumen might be superior for use in patients with an increased risk of aspiration. The Combitube, Easytube, and intubating laryngeal mask Fastrach showed the best capacity to withstand an increase of esophageal pressure.

Comparative study of airway management techniques with restricted access to patient airway

OBJECTIVE

To determine which airway endotracheal tube (ET), Combitube (CT), or Laryngeal Mask Airway (LMA) has the shortest time to successful ventilation in three nontraditional prehospital airway scenarios.

METHODS

Prospective randomized cohort study of emergency medicine (EM) residents, faculty EM physicians, and paramedics (EMT-P). Subjects were instructed to place an airway in a mannequin in three scenarios: mannequin supine under a table with head abutting a wall, mannequin sitting upright with access from behind, and mannequin lying on its side with access facing the mannequin. The number of airway placement attempts and time to successful ventilation were recorded.

RESULTS

Twenty-five resident physicians, 9 faculty physicians, and 22 EMT-Ps participated. No significant difference was found between the different airways in the number of attempts to successfully ventilate. EMT-Ps demonstrated significantly faster times to successful ventilation for all scenarios versus physicians (e.g., supine scenario with ET, EMT-P median time 57 seconds, physician median time 96 seconds) except for the mannequin lying on its side where there was no significant difference. The time to ventilation for all scenarios was less with the LMA versus ET or CT versus ET, except in the sitting scenario where ET and CT were comparable.

CONCLUSIONS

In this mannequin model of restricted airway access, LMA resulted in significantly faster times to ventilation versus ET and CT in all but one scenario. Further consideration and study using airways other than ET are warranted for situations with restricted access to the patient's airway.

A comparison of the laryngeal mask airway with facemask and oropharyngeal airway for manual ventilation by critical care nurses in children

The laryngeal mask airway is included as a first line airway device during adult resuscitation by first responders. However, there is little evidence for its role in paediatric resuscitation. Using anaesthetised children as a model for paediatric cardiopulmonary arrest, we compared the ability of critical care nurses to manually ventilate the anaesthetised child via the laryngeal mask airway compared with the facemask and oropharyngeal airway. The airway devices were inserted in random order and chest expansion was measured using an ultrasound distance transducer. The critical care nurses were able to place the laryngeal mask airway and achieve successful ventilation in 82% of children compared to 70% using the facemask and oropharyngeal airway, although the difference was not statistically significant (p = 0.136). The median time to first successful breath using the laryngeal mask airway was 39 s compared to 25 s using the facemask (p < 0.001). In this group of nurses, we did not show a difference in ventilation via a laryngeal mask airway or facemask, although facemask ventilation was achieved more quickly.

Anesthesiologists on ambulances: where do we stand?

PURPOSE OF REVIEW

This manuscript provides a critical review of the literature regarding the staffing of emergency medical services, with particular emphasis on anesthesiologists.

RECENT FINDINGS

Significant anesthesiology contributions to prehospital care include introduction of new airway management tools and improved physiological monitoring. Contributions to quality of care include patient benefit in terms of life years gained and a specific reduction in mortality from acute myocardial infarction. Intuitive concepts regarding the advantage of anesthesiologists in intubation mishaps and management of the failed airway have yet to be proven. Personnel limitations may be regional, necessitating local evaluation of anesthesiologist availability to staff ambulances. Since a major part of cost-effectiveness research is performed in the US where only paramedics staff ambulances, insufficient data exist regarding the financial implications of such practice. Burnout may be an important factor for deciding whether anesthesiologists should work in the operating room or ambulances or on an alternate basis.

SUMMARY

Further research should be performed to evaluate the clinical and financial implications of staffing ambulances with anesthesiologists or other physicians. Randomized controlled studies using standardized intubation techniques are necessary to examine whether prehospital airway management is improved when delivered by anesthesiologists.

Alternative airway devices for use in children requiring prehospital airway management: update and case discussion

This manuscript reviews the latest literature on alternative airways for use in children requiring prehospital airway management. Case discussions serve as a springboard for discussion of alternatives to bag-mask ventilation and endotracheal intubation for management of ventilation in infants and children in the prehospital setting. Few airway procedures have been studied with any rigor in this setting, and most of the data that are available are extrapolated from adults. Laryngeal mask airway may be the best alternative airway with the most promise to add to the armamentarium of the prehospital provider, but no controlled trial to date has been conducted.

Does the type of out-of-hospital airway interfere with other cardiopulmonary resuscitation tasks?

BACKGROUND

Out-of-hospital rescuers often perform tracheal intubation (TI) prior to other cardiopulmonary resuscitation (CPR) interventions. TI is a complex and error-prone procedure that may interfere with other key resuscitation tasks. We compared the effects of TI versus esophageal tracheal combitube (ETC) insertion on the accomplishment of other interventions during simulated cardiopulmonary resuscitation.

METHODS

In this prospective trial using a human simulator, two-paramedic teams simulated resuscitation of a ventricular fibrillation cardiopulmonary arrest using standard Advanced Cardiac Life Support guidelines. In each of two trials, teams used either TI or ETC as the primary airway device. Following delivery of three rescue shocks, we measured time intervals to successful airway placement, intravenous (IV) line insertion, drug administration, delivery of fourth rescue shock and completion of all four tasks. We also measured the total time without chest compressions. We compared task completion times using non-parametric statistics (Wilcoxon signed-ranks test) with a Bonferroni-adjusted p-value of 0.008.

RESULTS

Twenty teams each completed two scenarios. Participants required a median of 172.5 s (IQR: 146.5-225.5) to accomplish all four tasks. Elapsed time to airway placement was significantly less for ETC than TI (median difference 26.5 s (IQR 13-44.5), p=0.002). Time without chest compressions was less for ETC than TI (median difference 8.5 s (IQR 2.5-23.5), p=0.005). There were no differences between ETC and TI in times to IV placement (median difference 23.5 s (IQR -20 to 61), p=0.11), drug delivery (39.5 s (IQR -18 to 63), p=0.07), delivery of fourth rescue shock (39.5 s (IQR -21.5 to 87.5), p=0.07) or completion of all four tasks (33 s (IQR -11 to 74.5), p=0.08).

CONCLUSION

Compared with TI, ETC reduced time to airway placement and time without chest compressions, but did not affect elapsed times to accomplish other interventions. Additional time differences may be realized if translated to clinical out-of-hospital conditions.

Feasibility of flexible lightwand-guided tracheal intubation with the intubating laryngeal mask during out-of-hospital cardiopulmonary resuscitation by an emergency physician

BACKGROUND AND OBJECTIVE

We tested the feasibility of using the intubating laryngeal mask airway Fastrach (ILMA) as a ventilatory device and for flexible lightwand-guided tracheal intubation for out-of-hospital cardiopulmonary resuscitation by an emergency physician.

METHODS

After completion of a training programme, a single experienced emergency physician used the technique for all patients requiring out-of-hospital tracheal intubation over a 10-month period. If access to the head and neck was limited, the intubating laryngeal mask airway was inserted from below and to the side, otherwise it was inserted from above the head. Data about the time for the ambulance to reach the patient, whether or not access to the head and neck was limited, whether or not circulation was successfully restored, and the insertion and intubation success rates were noted.

RESULTS

The mean (range) time for the ambulance to reach the patient was 12 (10-20) min. Access to the head and neck was limited in 8/37 (22%). Circulation was successfully restored in 10/37 (27%). The intubating laryngeal mask airway was successfully inserted at the first attempt in 35/37 (95%) and at the second attempt in 2/37 (5%). The tracheal tube was successfully inserted in 25/37 (67.5%) at the first attempt, 7/37 (19%) at the second attempt and 5/37 (13.5%) at the third attempt. There were no overall failures for intubating laryngeal mask airway insertion or tracheal intubation. There were no differences in success rate between positions. Oesophageal intubation was detected and corrected in 2/37 (5%).

CONCLUSION

The intubating laryngeal mask airway has a high success rate as a ventilatory device and as a flexible lightwand-guided airway intubator during out-of-hospital cardiopulmonary resuscitation by a well-trained emergency physician. This technique may be particularly useful when there is limited access to the head and neck.

Out-of-hospital endotracheal intubation: where are we?

While remaining prominent in paramedic care and beneficial to some patients, out-of-hospital endotracheal intubation has not clearly improved survival or reduced morbidity from critical illness or injury when studied more broadly. Recent studies identify equivocal or unfavorable clinical effects, adverse events and errors, interaction with other important resuscitation interventions, and challenges in providing and maintaining procedural skill. We provide an overview of current data evaluating the overall effectiveness, safety, and feasibility of paramedic out-of-hospital endotracheal intubation. These studies highlight our limited understanding of out-of-hospital endotracheal intubation and the need for new strategies to improve airway support in the out-of-hospital setting.

Comparison of airway management with the intubating laryngeal mask, laryngeal tube and CobraPLA by paramedical students in anaesthetized patients

BACKGROUND

Because of the importance of airway management in emergency care, alternative methods with shorter learning curves for inexperienced personnel have been looked for as a substitute for endotracheal intubation (ETI).

METHODS

We compared the success of insertion, oxygenation and ventilation of the intubating laryngeal mask (ILMA), laryngeal tube (LT) and CobraPLA (COB) in anaesthetized patients when used by paramedical students. After informed consent, 96 patients were monitored and anaesthetized for general surgery without the use of a muscle relaxant. After the induction of anaesthesia, 32 paramedical students inserted the ILMA, LT or COB in a random order and ventilated the patient for a 60-s period. The number of insertion attempts, the time needed for insertion, and oxygenation and ventilation parameters were recorded. The students gave a subjective evaluation of the airway devices after the test.

RESULTS

Twenty-four of the 32 students (75%) successfully inserted ILMA at the first attempt, compared with 14 of 32 (44%) for LT and seven of 32 (22%) for COB (P<0.001, ILMA vs. COB). One student failed to insert ILMA after all three attempts, compared with seven of 32 (21%) using LT and seven of 32 (21%) using COB (P=not significant). Oxygenation and ventilation parameters did not differ between the groups after successful insertion.

CONCLUSION

Clinically inexperienced paramedical students can successfully use ILMA in anaesthetized patients. Further investigations are warranted to study whether ILMA or LT can replace ETI in emergency airway management when used by inexperienced medical or paramedical staff.

Airway management in emergency situations

Securing and monitoring the airway are among the key requirements of appropriate therapy in emergency patients. Failures to secure the airways can drastically increase morbidity and mortality of patients within a very short time. Therefore, the entire range of measures needed to secure the airway in an emergency, without intermediate ventilation and oxygenation, is limited to 30-40 seconds. Endotracheal intubation is often called the 'gold standard' for airway management in an emergency, but multiple failed intubation attempts do not result in maintaining oxygenation; instead, they endanger the patient by prolonging hypoxia and causing additional trauma to the upper airways. Thus, knowledge and availability of alternative procedures are also essential in every emergency setting. Given the great variety of techniques available, it is important to establish a well-planned, methodical protocol within the framework of an algorithm. This not only facilitates the preparation of equipment and the training of personnel, it also ensures efficient decision-making under time pressure. Most anaesthesia-related deaths are due to hypoxaemia when difficulty in securing the airway is encountered, especially in obstetrics during induction of anaesthesia for caesarean delivery. The most commonly occurring adverse respiratory events are failure to intubate, failure to recognize oesophageal intubation, and failure to ventilate. Thus, it is essential that every anaesthesiologist working on the labour and delivery ward is comfortable with the algorithm for the management of failed intubation. The algorithm for emergency airway management describing the sequence of various procedures has to be adapted to internal standards and to techniques that are available.

A Comparison of the Laryngeal Tube and Bag-Valve Mask Ventilation by Emergency Medical Technicians: A Feasibility Study in Anesthetized Patients

Airway management is of major importance in emergency care. The basic technique for all health care providers is bag-valve mask (BVM) ventilation, which requires skill and may be difficult to perform. Endotracheal intubation, which is the advanced method for securing the airway, is a demanding technique that has been shown to be associated with infrequent success, even when used by experienced paramedical personnel. Therefore, alternative airway devices have been sought. The use of the laryngeal tube (LT) by experienced anesthesia personnel had been studied in anesthetized patients and manikins in emergency medical training. We decided to evaluate the ability of inexperienced firefighter-emergency medical technician students (fire-EMT) to insert the LT or perform BVM in anesthetized patients. Thirty fire-EMTs randomly inserted the LT (n = 15) and performed 1 min of ventilation or used the BVM (n = 15). We found that all students successfully (100%) inserted the LT. Those who inserted the LT on the first attempt (73%) required 48.2 +/- 14.7 s for the insertion. Both the LT and BVM provided adequate oxygenation and ventilation. In this study, we found that inexperienced fire-EMT students inserted LT and performed 1-min ventilation with a reasonable success rate and insertion time in anesthetized patients.

The laryngeal tube for difficult airway management

BACKGROUND AND OBJECTIVE

Since the introduction of the laryngeal mask into clinical practice, various additional supraglottic ventilatory devices have been developed. Although it has been demonstrated that the laryngeal tube is an effective airway device during positive pressure ventilation no clinical study has been performed thus far regarding its use in patients with predicted ventilation and intubation difficulties.

METHODS

The aim of this study was to prospectively evaluate the use of the laryngeal tube for temporary oxygenation and ventilation in adult patients with supraglottic airway tumours scheduled to undergo a pharyngeal-laryngeal oesophagoscopy and bronchoscopy under general anaesthesia. In addition to our standard airway management with face mask ventilation and rigid bronchoscopy, all patients were temporarily ventilated with an laryngeal tube. Also, in patients requiring laryngeal biopsies, endotracheal intubation was performed with a 6.0 mm microlaryngeal tracheal tube. Minute ventilation volumes, tidal volumes, ventilation pressures, end-expiratory CO2 concentration, oxygen saturation and arterial blood gas samples were measured.

RESULTS

From 54 enrolled patients only patients with relevant tumour masses were evaluated (n = 23). Mask ventilation was performed without difficulty in 15 of 23 patients. Mechanical ventilation with the laryngeal tube was possible in 22 of 23 patients with an audible leak present in three. Conventional endotracheal intubation was successfully performed in 19 of 23 patients. During face mask ventilation, minute volume, tidal volume, ventilation pressure, end-tidal CO2, oxygen saturation and arterial PO2 were significantly lower and PCO2 significantly higher (P < 0.05, paired t-test). No statistically significant differences were noted between the laryngeal tube and the microlaryngeal tracheal tube.

CONCLUSIONS

The possibility of difficult ventilation and intubation must always be considered, in patients with supraglottic airway tumours. In these cases, the laryngeal tube can be considered for routine airway management and may be useful in the 'cannot-intubate' situation although difficulties should be anticipated in patients with previous irradiation, specifically of the throat area.

Should there be a change in the teaching of airway management in the medical school curriculum?

OBJECTIVE

To evaluate the use of the Laryngeal Mask Airway (LMA), the oesophageal-tracheal combitube (ETC) and the tracheal tube (TT) by medical students, with a view to recommend changes to the medical school curriculum.

METHODS

A prospective cohort study of 93 third-year medical students were taught the use of LMA, ETC and TT on manikins and had their skills tested at 0 and 6 months.

RESULTS

Overall, LMA insertion was the fastest technique with a mean time taken for successful insertion of 32.2 s, compared to that for ETC (55.0 s, P = 0.000) and TT (71.5s, P = 0.000). There was a significant delay in the time taken for insertion at 6 months for all three devices: 13.5 s for the LMA (P = 0.000), 29.6 s for the ETC (P = 0.000) and 31.8 s for the TT (P = 0.001). Both the ETC and the TT had a significantly lower first-attempt success rate at 6 months (ETC: 91% versus 63%, P = 0.000 and TT: 80% versus 55%, P = 0.003) but not the LMA (96% versus 92%, P = 0.549). At 6 months, the overall success rate was 99% for the LMA, 100% for the ETC and 93% for the TT. Complication rate was higher for the ETC (9% versus 46%, P = 0.000) and the TT (38% versus 78%, P = 0.005) but not for the LMA (3% versus 10%, P = 0.688).

CONCLUSIONS

The use of the TT is difficult and the skills acquired by the medical students deteriorate significantly over time. The LMA and the ETC seem to have an advantage over the TT in that they are more easily learnt and the skills better retained. It is recommended that these alternative devices be included in the medical school curriculum for airway management.

Assessing resident skills in the use of rescue airway devices

STUDY OBJECTIVE

Airway control is a vital procedure for the specialty of emergency medicine. Although endotracheal intubation is the preferred method to obtain a definitive airway, several devices have been developed to help physicians handle a difficult or failed intubation. Using a bench model, we assessed the efficacy of an advanced airway training program.

METHODS

Residents of an Accreditation Council for Graduate Medical Education-accredited 3-year emergency medicine residency program participated in an advanced airway course. Psychomotor skills were assessed for the laryngeal mask airway, intubating laryngeal mask airway (Fastrac), and Combitube (esophageal-tracheal twin-lumen airway device). The outcome variable was the time necessary to successfully insert and ventilate an airway mannequin. The skills were assessed at 0, 6, and 12 months after training. Information including previous and interval experience with these devices was recorded.

RESULTS

The airway mannequin was successfully ventilated using the laryngeal mask airway, Fastrac, and Combitube in 6.9, 51.0, and 21.5 seconds, respectively. There was a modest interval increase in mean time required to place the laryngeal mask airway and Combitube at 6 and 12 months after training. A decrease was noted in the time to place the Fastrac. Previous and interval experience did not affect performance.

CONCLUSION

Airway competency is a key component of emergency medicine training. Training should include mastery of rescue devices for the failed or difficult airway. Our findings suggest that emergency medicine residents can learn and retain these airway skills.

Impact of informed consent requirements on cardiac arrest research in the United States: exception from consent or from research?

INTRODUCTION

Research in patients with life-threatening illness such as cardiac arrest is challenging since they can not consent. The Food and Drug Administration addressed research under emergency conditions by publishing new criteria for exception from informed consent in 1996. We systematically reviewed randomized trials over a 10-year period to assess the impact of these regulations.

METHODS

Case-control study of published trials for cardiac arrest (cases) and atrial fibrillation (controls.) Studies were identified by using structured searches of MEDLINE and EMBASE from 1992 to 2002. Included were studies using random allocation in humans with cardiac arrest or atrial fibrillation prior to enrollment. Excluded were duplicate publications. Number of American trials, foreign trials and proportion of trials of American origin were compared by using regression analysis. Changes in cardiac arrest versus atrial fibrillation trials were calculated as risk differences.

RESULTS

Of 4982 identified cardiac arrest studies, 57 (1.1%) were randomized trials. The number of American cardiac arrest trials decreased by 15% (95% CI: 8, 22%) annually (P = 0.05). The proportion of cardiac arrest trials of American origin decreased by 16% (95% CI: 10, 22%) annually (P = 0.006). Of 5596 identified atrial fibrillation studies, 197 trials (3.5%) were randomized trials. The risk difference between cardiac arrest versus atrial fibrillation trials being of American origin decreased significantly (annual difference -5.8% (95% CI: -10, -0.1%), P = 0.03).

INTERPRETATION

Fewer American cardiac arrest trials were published during the last decade, when federal consent requirements changed. Regulatory requirements for clinical trials may inhibit improvements in care and threaten public health.

The airway approach algorithm: a decision tree for organizing preoperative airway information

Anticipatory decision-making in airway management requires the integration of both history and physical examination findings. Though all airways can be managed along some branch of the American Society of Anesthesiologists' (ASA) Difficult Airway Algorithm, by predicting specific difficulties and integrating this information into an airway approach strategy, emergency branches of the ASA algorithm may be avoided. The Airway Approach Algorithm (AAA) consists of five clinical questions, with "yes" or "no" answers, to be addressed prior to the management of the airway. A positive answer to any question leads the clinician to the next, whereas a negative answer directs the operator to a root point of the ASA algorithm. The AAA is introduced with the anticipation that trainees in Anesthesiology, as well as others, will find it helpful in organizing preoperative information concerning the airway.

Laryngeal mask airway control versus endotracheal intubation by medical personnel wearing protective gear

The purpose of this study was to evaluate the rates of successful airway control using endotracheal tubes (ETs) or laryngeal mask airways (LMAs) and compare them between anesthetists and non-anesthetists wearing full antichemical protective gear. Anesthetists and non-anesthetists (n = 10 per group) twice attempted inserting ETs and LMAs on a mannequin model of airway management in a crossover, prospective manner. Times to successful insertion and failure rates were recorded. Non-anesthetists had a slightly higher failure rate inserting ETs compared with anesthetists (P = not significant). Respective mean times to successfully inserting ETs were 38 +/- 7.1 and 26.4 +/- 7.5 seconds (P < .05). Both groups inserted LMAs more rapidly than ETs (P < .05) and their failure rates in ET use were higher. In view of the relative rapidity by which LMAs were inserted as compared with ETs, by fully protected caregivers, the incorporation of LMA in algorithms dealing with emergency airway management in a nonconventional mass casualty scenario deserves further evaluation.

Evaluation of the oesophageal-tracheal double-lumen tube (Combitube) during general anaesthesia

OBJECTIVES

Evaluation of safety and effectiveness of the Combitube during general anaesthesia.

PATIENTS AND METHODS

250 patients undergoing general anaesthesia were enrolled in the study. The respective types and duration of surgery, ease of insertion of the Combitube, and potential complications were recorded. Maximum ventilatory pressures and leak fraction were also evaluated in this study.

RESULTS

Duration of surgery varied between 20 and 410 min. More than 96% of the blind Combitube insertions were successful at the first attempt, with a mean time of less than 18 +/- 5 seconds (range 12-24 seconds). In 99% of patients the Combitube worked well, and adequate oxygenation and ventilation was possible. All patients were haemodynamically stable during the entire duration of surgery. In all patients, pulse oximetry showed an oxygen saturation of 97 +/- 2% and an end-tidal carbon dioxide of 38 +/- 6 mmHg. Leak fraction, calculated as a fraction of the inspired volume, did not increase to more than 5% up to a ventilation pressure of 40 cm H2O. Superficial laceration occurred in 18 patients (7.2%) without further sequelae. No severe injuries were observed during the study period.

CONCLUSION

Ventilation via the Combitube appears to be safe and effective during general anaesthesia. Practice in elective cases is a requirement for successful use in an emergency situation.

Airway management in neurological emergencies

Several neurological conditions may present to the emergency department (ED) with airway compromise or respiratory failure. The severity of respiratory involvement in these patients may not always be obvious. Proper pulmonary management can significantly reduce the respiratory complications associated with the morbidity and mortality of these patients. Rapid sequence intubation (RSI) is the method of choice for definitive airway management in the ED and is used for the majority of intubations. The unique clinical circumstances of each patient dictates which pharmacological agents can be used for RSI. Several precautions must be taken when using these drugs to minimize potentially fatal complications. Noninvasive positive pressure ventilation may obviate the need for intubation in a select population of patients. This article reviews airway management, with a particular emphasis on the use of RSI for common neurological problems presenting to the ED.

Insertion of the LMA-Unique™ with and without digital intraoral manipulation by inexperienced personnel after manikin-only training

In a randomized, crossover study, we compared insertion of the LMA-Unique with and without digital intraoral manipulation by inexperienced personnel after manikin-only training. Ten registered nurses with no hands-on clinical experience of airway management and 100 anesthetized, paralyzed adults (ASA Status 1-2, aged 18-80 years) participated in the trial. Training comprised: 1) a 30-min didactic lecture; 2) a 3-min description of each of the insertion techniques; 3) a 3-min demonstration of each technique using a manikin; 4) 10 min of supervised training on the manikin with each technique. The time to achieve an effective airway (2 consecutive expired tidal volumes >/= 8 ml/kg; maximum 90 s or 3 attempts allowed) and the number of insertion attempts were determined by analysis of digital video recordings. Any blood staining on the first randomized device was noted at removal. The first attempt success rate (with digital intraoral manipulation, 84%; without digital intraoral manipulation, 87%) and overall success rate (with digital intraoral manipulation, 94%; without digital intraoral manipulation, 93%) were similar. Effective airway time was shorter without digital intraoral manipulation (43 +/- 17 vs. 33 +/- 15 s). Blood staining was detected in 12% (6/50) with and 16% (8/50) without digital intraoral manipulation (not significant). There were no differences in performance among nurses. We conclude that insertion of the LMA-Unique is equally successful with or without digital intraoral manipulation by inexperienced personnel in paralyzed adults after manikin-only training. Successful insertion of the LMA-Unique does not require insertion of the finger into the patient's mouth.

The Combitube as a salvage airway device for paramedic rapid sequence intubation

STUDY OBJECTIVE

The safety of out-of-hospital rapid sequence intubation depends on a reliable strategy when orotracheal intubation is unsuccessful. Here we describe our experience with the Combitube (esophageal-tracheal twin-lumen airway device) as a salvage airway device for paramedic rapid sequence intubation.

METHODS

The San Diego Paramedic Rapid Sequence Intubation Trial was performed to assess the effect of paramedic rapid sequence intubation on outcome in severely head-injured patients. Adults with severe head trauma (Glasgow Coma Scale score 3 to 8) who were unable to be intubated without medications were enrolled. Midazolam and succinylcholine were administered, and paramedics were allowed a maximum of 3 attempts at orotracheal intubation. If the attempts were unsuccessful, Combitube insertion was mandated. After confirmation of tube position, rocuronium was given and standard ventilation protocols were used. The primary outcome measure for this analysis was the success rate for Combitube insertion after unsuccessful orotracheal intubation. In addition, Combitube insertion and orotracheal intubation patients were compared with regard to demographic, clinical, and outcome data.

RESULTS

A total of 426 patients were enrolled in the trial, with 420 meeting inclusion criteria for this analysis. Orotracheal intubation was successful in 355 (84.5%) of 420; Combitube insertion was successful in 58 (95.1%) of 61 attempts, with no reported complications. Patients undergoing Combitube insertion had higher Face Abbreviated Injury Scale scores and were more likely to have oropharyngeal blood or vomitus. Arrival Pco(2) values were higher, and arrival Po(2) values were lower but still supranormal in patients undergoing Combitube insertion. There were no mortality differences between patients undergoing Combitube insertion and those undergoing orotracheal intubation.

CONCLUSION

The Combitube can be an effective salvage airway device for paramedic rapid sequence intubation in an urban/suburban, high-volume emergency medical services system with paramedics who are experienced in Combitube placement and with stringent protocols for its use. The device should be tested in other sizes and types of systems and under less medical scrutiny than was used in this study.

Effective use of the esophageal tracheal Combitube™ following severe burn injury

We present the case of a patient status post previous burn injury, undergoing elective surgery in which the Combitube was used because contractural formation of the mouth and tracheal stenosis precluded tracheal intubation. The Combitube proved to be highly successful in this patient who had a very limited mouth opening.

A comparison of the ProSeal and classic laryngeal mask airways for airway management by inexperienced personnel after manikin-only training

We compared the ProSeal (PLMA) and Classic (LMA) laryngeal mask airway for airway management by inexperienced personnel. Nine nurses from the post-anaesthesia care unit, with no prior experience of LMA or PLMA insertion, were observed inserting the LMA and PLMA in 60 ASA 1 to 2 anaesthetized, paralyzed adults following manikin-only training. The time to achieve an effective airway (2 consecutive expired tidal volumes (6 ml/kg; maximum 2 minutes allowed), the number of insertion attempts and the reasons for failure (inability to insert into pharynx or inadequate ventilation) were determined by analysis of digital video recordings. The first attempt success rate (LMA, 85%; PLMA, 83%), overall success rate (LMA, 88%; PLMA, 90%) and effective airway time (LMA, 39 +/- 13 s; PLMA, 43 +/- 19 s) were similar. Failure was from an inability to insert into the pharynx in five with the LMA and three with the PLMA, and inadequate ventilation with two from the LMA and three from the PLMA. Effective airway time and the number of failures were similar for the first and second device. Failure of both devices occurred in four patients. We conclude that airway management in anaesthetized, paralyzed adults is equally successful for the LMA and PLMA by inexperienced personnel following manikin-only training. The PLMA is worthy of consideration as a tool for emergency airway management by inexperienced personnel.

Management of the difficult airway: alternative airway techniques and adjuncts

Rapid-sequence intubation using conventional laryngoscopic technique remains the standard of airway management in emergency medicine and continues to have a success rate of approximately 98%. Preparation and proper intubation technique must be optimized at the initial attempt using direct laryngoscopy. Failure causes multiple repeated attempts, leading to a failed airway. Each repeated attempt increases the likelihood of bleeding, oral, pharyngeal, and laryngeal edema, and malposition, causing decreased visualization of the glottic opening, equipment failure, and hypoxia. Preparation must be an ongoing process. Faulty suction, no oxygen source, choice of the wrong laryngoscopic blade or ETT, poor light source, or misplaced equipment can domino into mechanical failure. Intubation equipment stations must be inventoried constantly, organized, and kept simple in their layout to decrease confusion during selection. Medication for sedation and paralysis should be readily available and not kept distant from the intubation station in a medication-dispensing unit that would require time for acquisition. Proper positioning of the patient remains paramount for alignment of the oral, pharyngeal, and laryngeal axis to provide optimal visualization of the vocal cords. Proper technique during insertion of the laryngoscope blade in the oral cavity for displacement of the tongue must be ensured. Without proper technique, even with proper positioning, the glottic opening cannot be visualized. Laryngeal pressure to maneuver the larynx into position should be exerted initially by the laryngoscopist's right hand and, when in view, maintained by an assistant to free the laryngoscopist's hand for ETT insertion. With preparation and proper technique, the first attempt is the best attempt, and the vicious cycle of multiple attempts and complications will be averted.

Comparison of a conventional tracheal airway with the Combitube in an urban emergency medical services system run by physicians

This prospective randomised study was performed to compare the use of the Esophageal-Tracheal Combitube(R) (ETC; Tyco Healthcare, Mansfield, MA; http://www.combitube.org) with a conventional tracheal airway (ETA) for airway management by experienced physicians of the Emergency Medical Services System of the City of Vienna in the prehospital setting. Access to the patient's head, time of arrival of the ambulance, ease of insertion, time of insertion, potential substitution by the alternate airway, efficacy of adrenaline (epinephrine) administered via the airway, survival to the intensive care unit (ICU) ward and survival to discharge from the hospital were evaluated. One hundred and seventy-two non-traumatic cardiac arrest patients (131 males, 41 females) were enrolled in this study during a 12 months period. In 83 patients (48.3%), the conventional ETA (group 1) was used for the initial intubation attempt which was successful in 78 patients (94%). The remaining five patients of group 1 could not be intubated with an ETA, but were successfully managed with the ETC. Eighty-nine patients (51.7%) were intubated with the ETC (group 2) as first choice (79 in oesophageal position (89%); eight in tracheal position: (9%)), which was successful in 87 (98%) patients. The remaining two patients in group 2 (2%) were successfully managed with the ETA. Success of intubation and ventilation with ETC was comparable to the ETA. Recorded time of insertion was shorter with the ETC versus ETA (P<0.05). The Combitube worked well in cases of difficult access to the patient's head and in bleeding and vomiting patients. Both devices served as successful substitutes for each other. Adrenaline (epinephrine) applied via ETC with a 10-fold dosage was as effective as via the conventional ETA. To our knowledge this is the first study using physicians comparing ETC and ETA in the prehospital setting.

Comparison of times to intubate a simulated trauma patient in two positions

BACKGROUND

The nature of the trauma patient's injuries may compromise the airway and ultimately lead to death or neurological devastation. The same injuries complicate protecting the airway in these patients by preventing manipulation of the cervical spine for direct laryngoscopy. A recent study has shown that misplaced endotracheal tubes occur significantly more often in trauma patients than in medical patients.

OBJECTIVES

The authors hypothesized that elevating the long spine board would reduce the amount of time required for paramedics to intubate a simulated trauma patient.

METHODS

Paramedics from an urban emergency medical services division were given up to two opportunities to intubate a manikin in a type I ambulance in each of two positions in random order: supine and with the head elevated. The manikin was secured to a long spine board with three straps, a semi-rigid cervical collar, and a cervical immobilization device. An investigator maintained cervical spine alignment and provided cricoid pressure. The elevated position was accomplished by raising the head of the stretcher 27 degrees, resulting in 7 degrees of spine board elevation. Each attempt was timed. If the first attempt was unsuccessful, the times for both the first and second attempts were totaled to determine the total time required for intubation. Times for successful intubation in each position were compared with a Mann-Whitney test. First-attempt success rates for each position were compared with chi2 analysis. Multinomial regression was used to determine whether experience, paramedic height, or previous intubation success influenced intubation time in either position.

RESULTS

Fifty-five paramedics provided informed consent and completed the study. Average time to intubate the supine manikin was significantly longer than needed to intubate the head-elevated manikin (35.6 +/- 19.0 seconds vs 27.9 +/- 12.8 seconds, p = 0.025). The manikin was successfully intubated on the first attempt 84% in the supine position and 95% in the head-elevated position (p = 0.200). Regression analysis identified intubation position as the only significant predictor of intubation time (p = 0.007).

CONCLUSIONS

Modest elevation of the head of an immobilized patient appears to allow more rapid intubation. With the spine board properly secured to the stretcher, this technique potentially offers improved intubation time without additional cost or equipment.

The Esophageal-Tracheal Combitube

The ETC is an easily inserted, double-lumen/double-balloon supraglottic airway device. The major indication of the ETC is as a back-up device for airway management. It is an excellent option for rescue ventilation in both in- and out-of-the-hospital environments and in situations of difficult ventilation and intubation. It is useful especially in patients with massive airway bleeding or limited access to the airway and in patients in whom neck movement is contraindicated. Continued airway management with an ETC that has been placed is a reasonable option in many cases. Having thus secured the airway, it may not be necessary to abort the anesthetic or to continue with further airway management efforts. In order to avoid serious trauma to the esophagus or airway, redesigning the ETC using a softer material for the tube is advisable.

Role of rapid sequence induction for intubation in the prehospital setting: helpful or harmful?

Use of rapid sequence induction for intubation was introduced to the prehospital environment in the hope of enhancing patient outcome by improving early definitive airway management. Varying success has been achieved in both air and ground transport emergency medical services systems, but concern persists about the potential to cause patients harm. Individual emergency medical services systems must determine the need for rapid sequence induction for intubation and their ability to implement a rapid sequence induction for intubation protocol effectively with minimal adverse events. Therefore, the value of rapid sequence induction for intubation is dependent on each emergency medical services system design in their ability to establish personnel requirements and ongoing training, expertise in airway management skills, medical direction and supervision, and a quality assurance program. If these principles are strictly adhered to, rapid sequence induction for intubation may be safely used as an advanced airway management technique in the prehospital setting.