Physiologically difficult airway in critically ill patients: winning the race between haemoglobin desaturation and tracheal intubation

Tracheal intubation in critically ill adults with a physiologically difficult airway. An international Delphi study

PURPOSE

Our study aimed to provide consensus and expert clinical practice statements related to airway management in critically ill adults with a physiologically difficult airway (PDA).

METHODS

An international Steering Committee involving seven intensivists and one Delphi methodology expert was convened by the Society of Critical Care Anaesthesiologists (SOCCA) Physiologically Difficult Airway Task Force. The committee selected an international panel of 35 expert clinician-researchers with expertise in airway management in critically ill adults. A Delphi process based on an iterative approach was used to obtain the final consensus statements.

RESULTS

The Delphi process included seven survey rounds. A stable consensus was achieved for 53 (87%) out of 61 statements. The experts agreed that in addition to pathophysiological conditions, physiological alterations associated with pregnancy and obesity also constitute a physiologically difficult airway. They suggested having an intubation team consisting of at least three healthcare providers including two airway operators, implementing an appropriately designed checklist, and optimizing hemodynamics prior to tracheal intubation. Similarly, the experts agreed on the head elevated laryngoscopic position, routine use of videolaryngoscopy during the first attempt, preoxygenation with non-invasive ventilation, careful mask ventilation during the apneic phase, and attention to cardiorespiratory status for post-intubation care.

CONCLUSION

Using a Delphi method, agreement among a panel of international experts was reached for 53 statements providing guidance to clinicians worldwide on safe tracheal intubation practices in patients with a physiologically difficult airway to help improve patient outcomes. Well-designed studies are needed to assess the effects of these practice statements and address the remaining uncertainties.

Hospital cohort study on survival predictors for intubated coronavirus disease 2019 patients

OBJECTIVE

The objective of this study was to assess the predictors of survival among patients with coronavirus disease 2019 who underwent tracheal intubation, as part of a hospital cohort study.

METHODS

This retrospective cohort study in the Rio do Sul County Hospital, Santa Catarina, Brazil, from April 2020 to May 2021, focused on patients aged 18 years or older intubated for coronavirus disease 2019. We assessed the 90-day survival of intubated patients by estimating the hazard ratio using a Cox proportional hazards regression model.

RESULTS

The study included 132 participants, with an average age of approximately 60 years. Tracheal intubation was successfully accomplished in 97% of cases within two attempts. The overall mortality rate was 62.9%. Notably, mortality rates were significantly higher in patients aged over 60 years (hazard ratio=2.57; 95%CI 1.54-4.29; p<0.001), those with blood oxygen saturation below 85% (hazard ratio=1.92; 95%CI 1.03-3.57; p=0.04), instances where tracheal intubation was carried out using a conventional laryngoscope (hazard ratio=2.59; 95%CI 1.22-5.48; p=0.013), and when performed by emergency physicians (hazard ratio=3.96; 95%CI 1.51-10.4; p=0.005).

CONCLUSION

Our analysis unveiled that the risk of death in intubated coronavirus disease 2019 patients is four times higher when an emergency physician, as opposed to an anesthesiologist, leads the tracheal intubation team.

Implementation of a Rapid Sequence Intubation Checklist Improves First-Pass Success and Reduces Peri-Intubation Hypoxia in Air Medical Transport

OBJECTIVE

Rapid sequence intubation (RSI) is a critical skill commonly performed by air medical teams in the United States. To improve safety and reduce potential patient harm, checklists have been implemented by various institutions in intensive care units, emergency departments, and even prehospital air medical programs. However, the literature suggests that checklist use before RSI has not shown improvement in clinically important outcomes in the hospital. It is unclear if RSI checklist use by air medical crews in prehospital environments confers any clinically important benefit.

METHODS

This institutional review board-approved project is a before-and-after observational study conducted within a large helicopter ambulance company. The RSI checklist was used by flight crewmembers (flight paramedic/nurse) for over 3 years. Data were evaluated for 8 quarters before and 8 quarters after checklist implementation, spanning December 2014 to March 2019. Data were collected, including the self-reported use of the checklist during intubation attempts, the reason for intubation, and correlation with difficult airway predictors (HEAVEN [Hypoxemia, Extremes of size, Anatomic disruption, Vomit, Exsanguination, Neck mobility/Neurologic injury] criteria), and compared with airway management before the implementation of the checklist. The primary outcome was improved first-pass success (FPS) when compared among those who received RSI before the checklist versus those who received RSI with the checklist. The secondary outcome was a definitive airway sans hypoxia improvement noted on the first pass among adult patients as measured before and after RSI checklist implementation. Post-RSI outcome scenarios were recorded to analyze and validate the effectiveness of the checklist.

RESULTS

Ten thousand four hundred five intubations were attempted during the study. FPS was achieved in 90.9% of patients before RSI checklist implementation, and 93.3% achieved FPS postimplementation of the RSI checklist (P ≤ .001). In the preimplementation epoch, 36.2% of patients had no HEAVEN predictors versus 31.5% after RSI checklist implementation. These data showed that before RSI checklist implementation, airways were defined as less difficult than after implementation.

CONCLUSION

The implementation of a standardized RSI checklist provided a better identification of deterring factors, affording efficient and accurate actions promoting FPS. Our data suggest that when a difficult airway is identified, using the RSI checklist improves FPS, thereby reducing adverse events.

Diagnosis and Management of Acute Respiratory Failure

Acute hypoxemic respiratory failure is defined by Pao2 less than 60 mm Hg or SaO2 less than 88% and may result from V/Q mismatch, shunt, hypoventilation, diffusion limitation, or low inspired oxygen tension. Acute hypercapnic respiratory failure is defined by Paco2 ≥ 45 mm Hg and pH less than 7.35 and may result from alveolar hypoventilation, increased fraction of dead space, or increased production of carbon dioxide. Early diagnostic maneuvers, such as measurement of SpO2 and arterial blood gas, can differentiate the type of respiratory failure and guide next steps in evaluation and management.

Derivation of the Difficult Airway Physiological Score (DAPS) in adults undergoing endotracheal intubation in the emergency department

BACKGROUND

Prediction of serious outcomes among patients with physiological instability is crucial in airway management. In this study, we aim to develop a score to predict serious outcomes following intubation in critically ill adults with physiological instability by using clinical and laboratory parameters collected prior to intubation.

METHOD

This single-center analytical cross-sectional study was conducted in the Emergency Department from 2016 to 2020. The airway score was derived using the transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD) methodology. To gauge model's performance, the train-test split technique was utilized. The discrete random number generation approach was used to divide the dataset into two groups: development (training) and validation (testing). The validation dataset's instances were used to calculate the final score, and its validity was measured using ROC analysis and area under the curve (AUC). By computing the Youden's J statistic using the metrics sensitivity, specificity, positive predictive value, and negative predictive value, the discriminating factor of the additive score was determined.

RESULTS

The mean age of the 1021 patients who needed endotracheal intubations was 52.2 years (± 17.5), and 632 (62%) of them were male. In the development dataset, there were 527 (64.9%) physiologically difficult airways, 298 (36.7%) post-intubation hypotension, 124 (12%) cardiac arrest, 347 (42.7%) shock index > 0.9, and 456 [56.2%] instances of pH < 7.3. On the contrary, in the validation dataset, there were 143 (68.4%) physiologically difficult airways, 33 (15.8%) post-intubation hypotension, 41 (19.6%) cardiac arrest, 87 (41.6%) shock index > 0.9, and 121 (57.9%) had pH < 7.3, respectively. There were 12 variables in the difficult airway physiological score (DAPS), and a DAPS of 9 had an area under the curve of 0.857. The accuracy of DAPS was 77%, the sensitivity was 74%, the specificity was 83.3%, and the positive predictive value was 91%.

CONCLUSION

DAPS demonstrated strong discriminating ability for anticipating physiologically challenging airways. The proposed model may be helpful in the clinical setting for screening patients who are at high risk of deterioration.

Factors Associated With Desaturation in Prehospital Rapid Sequence Intubation in a Helicopter Emergency Medical Service

OBJECTIVE

Desaturation during prehospital rapid sequence intubation (RSI) is common and is associated with patient morbidity. Past studies have identified oxygen saturations at induction, the grade of laryngoscopy, and multiple attempts to intubate as being associated with desaturation. This study aimed to investigate whether there are other factors, identifiable before RSI, associated with desaturation.

METHODS

This was a study of a physician-paramedic critical care team operating as Aeromedical Operations, NSW Ambulance. Prehospital RSIs (using paralysis) were studied retrospectively via patient case notes, monitor data, and an airway database. The review occurred between April 1, 2016, and December 31, 2018. Desaturation was defined as monitor recordings of saturations ≤ 92%. Logistic regression was performed for factors likely to be associated with desaturation.

RESULTS

Desaturation occurred in 67 of 350 (19.1%) RSIs. Factors significantly associated with desaturation included male sex, a chest injury, increased weight, and lower saturations pre-RSI.

CONCLUSION

Increased weight, chest injuries, and lower oxygen saturations are associated with desaturation at RSI. The variable male sex may be a surrogate for other as-yet unidentified factors.

Spanish Society of Anesthesiology, Reanimation and Pain Therapy (SEDAR), Spanish Society of Emergency and Emergency Medicine (SEMES) and Spanish Society of Otolaryngology, Head and Neck Surgery (SEORL-CCC) Guideline for difficult airway management. Part I

The Airway Management section of the Spanish Society of Anesthesiology, Resuscitation, and Pain Therapy (SEDAR), the Spanish Society of Emergency Medicine (SEMES), and the Spanish Society of Otorhinolaryngology and Head and Neck Surgery (SEORL-CCC) present the Guide for the comprehensive management of difficult airway in adult patients. Its principles are focused on the human factors, cognitive processes for decision-making in critical situations, and optimization in the progression of strategies application to preserve adequate alveolar oxygenation in order to enhance safety and the quality of care. The document provides evidence-based recommendations, theoretical-educational tools, and implementation tools, mainly cognitive aids, applicable to airway management in the fields of anesthesiology, critical care, emergencies, and prehospital medicine. For this purpose, an extensive literature search was conducted following PRISMA-R guidelines and was analyzed using the GRADE methodology. Recommendations were formulated according to the GRADE methodology. Recommendations for sections with low-quality evidence were based on expert opinion through consensus reached via a Delphi questionnaire.

Bed tilt and ramp positions are associated with increased first-pass success of adult endotracheal intubation in the emergency department: A registry study

OBJECTIVE

Successful endotracheal intubation in the ED requires optimum body positioning. In patients with obesity, the ramp position was suggested to achieve better intubating conditions. However, limited data are available on the airway management practices for patients with obesity in Australasian EDs. The aim of this study was to identify current patient positioning practices during endotracheal intubation and its association with first-pass success (FPS) at intubation and adverse event (AE) rates in obese and non-obese populations.

METHODS

Prospectively collected data from the Australia and New Zealand ED Airway Registry (ANZEDAR) between 2012 and 2019 were analysed. Patients were categorised into two groups according to their weight: <100 kg (non-obese) or ≥100 kg (obese). Four position categories were investigated; supine, pillow or occipital pad, bed tilt and ramp or head-up with relation to FPS and complication rate using logistic regression modelling.

RESULTS

A total of 3708 intubations from 43 EDs were included. Overall, the non-obese cohort had a greater FPS rate (85.9%) compared to the obese group (77.0%). The bed tilt position had the highest FPS rate (87.2%), whereas the supine position had the lowest (83.0%). AE rates were highest in the ramp position (31.2%) compared to all other positions (23.8%). Regression analysis showed ramp, or bed tilt positions and a consultant-level intubator were associated with higher FPS. Obesity, in addition to other factors, was independently associated with lower FPS.

CONCLUSION

Obesity was associated with lower FPS, which could be improved through performing a bed tilt or ramp positioning.

High-risk criteria for the physiologically difficult paediatric airway: A multicenter, observational study to generate validity evidence

BACKGROUND

Single-center studies have identified risk factors for peri-intubation cardiac arrest in the emergency department (ED). The study objective was to generate validity evidence from a more diverse, multicenter cohort of patients.

METHODS

We completed a retrospective cohort study of 1200 paediatric patients who underwent tracheal intubation in eight academic paediatric EDs (150 per ED). The exposure variables were 6 previously studied high-risk criteria for peri-intubation arrest: (1) persistent hypoxemia despite supplemental oxygen, (2) persistent hypotension, (3) concern for cardiac dysfunction, (4) post-return of spontaneous circulation (ROSC), (5) severe metabolic acidosis (pH < 7.1), and (6) status asthmaticus. The primary outcome was peri-intubation cardiac arrest. Secondary outcomes included extracorporeal membrane oxygenation (ECMO) cannulation and in-hospital mortality. We compared all outcomes between patients that met one or more versus no high-risk criteria, using generalized linear mixed models.

RESULTS

Of the 1,200 paediatric patients, 332 (27.7%) met at least one of 6 high-risk criteria. Of these, 29 (8.7%) suffered peri-intubation arrest compared to zero arrests in patients meeting none of the criteria. On adjusted analysis, meeting at least one high-risk criterion was associated with all 3 outcomes - peri-intubation arrest (AOR 75.7, 95% CI 9.7-592.6), ECMO (AOR 7.1, 95% CI 2.3-22.3) and mortality (AOR 3.4, 95% 1.9-6.2). Four of 6 criteria were independently associated with peri-intubation arrest: persistent hypoxemia despite supplemental oxygen, persistent hypotension, concern for cardiac dysfunction, and post-ROSC.

CONCLUSIONS

In a multicenter study, we confirmed that meeting at least one high-risk criterion was associated with paediatric peri-intubation cardiac arrest and patient mortality.

The impact of intravenous dodecafluoropentane on a murine model of acute lung injury

INTRODUCTION

Intravenous oxygen therapeutics present an appealing option for improving arterial oxygenation in patients with acute hypoxemic respiratory failure, while limiting iatrogenic injury from conventional respiratory management.

METHODS

We used an established two-hit murine model of acute lung injury (ARDS/VILI) to evaluate the effect of intravenous dodecafluoropentane (DDFPe) on oxygen saturation and bronchoalveolar lavage cell counts and protein levels. Twenty hours after challenge with intratracheal lipopolysaccharide, mice were intubated and ventilated with high tidal volumes (4 h) to produce acute lung injury. DDFPe (0.6 mL/kg) or saline was administered by IV bolus injection at the initiation of mechanical ventilation and again at 2 h. Oxygen saturation was measured every 15 min. Bronchoalveolar lavage was performed at the conclusion of the experiment.

RESULTS

The two-hit ARDS/VILI model produced substantial inflammatory acute lung injury reflected by markedly increased bronchoalveolar lavage (BAL) cell counts compared to BAL cell counts in spontaneous breathing controls (5.29 ± 1.50 × 10^-6 vs 0.74 ± 0.014 × 10^-6 cells/mL) Similarly, BAL protein levels were markedly elevated in ARDS/VILI-challenged mice compared with spontaneous breathing controls (1109.27 ± 223.80 vs 129.6 ± 9.75 ng/mL). We fit a linear mixed effects model that showed a significant difference in oxygen saturation over time between DDFPe-treated mice and saline-treated mice, with separation starting after the 2-h injection. DDFPe-treated ARDS/VILI-challenged mice also exhibited significant reductions in BAL cell counts but not in BAL protein.

CONCLUSION

DDFPe improves oxygen saturation in a murine model of ARDS/VILI injury with the potential for serving as an intravenous oxygen therapeutic.

Intubation first-pass success in a high performing pre-hospital critical care system is not associated with 30-day mortality: a registry study of 4496 intubation attempts

BACKGROUND

Lower intubation first-pass success (FPS) rate is associated with physiological deterioration, and FPS is widely used as a quality indicator of the airway management of a critically ill patient. However, data on FPS's association with survival is limited. We aimed to investigate if the FPS rate is associated with 30-day mortality or physiological complications in a pre-hospital setting. Furthermore, we wanted to describe the FPS rate in Finnish helicopter emergency medical services.

METHODS

This was a retrospective observational study. Data on drug-facilitated intubation attempts by helicopter emergency medical services were gathered from a national database and analysed. Multivariate logistic regression, including known prognostic factors, was performed to assess the association between FPS and 30-day mortality, collected from population registry data.

RESULTS

Of 4496 intubation attempts, 4082 (91%) succeeded on the first attempt. The mortality rates in FPS and non-FPS patients were 34% and 38% (P = 0.21), respectively. The adjusted odds ratio of FPS for 30-day mortality was 0.88 (95% CI 0.66-1.16). Hypoxia after intubation and at the time of handover was more frequent in the non-FPS group (12% vs. 5%, P < 0.001, and 5% vs. 3%, P = 0.01, respectively), but no significant differences were observed regarding other complications.

CONCLUSION

FPS is not associated with 30-day mortality in pre-hospital critical care delivered by advanced providers. It should therefore be seen more as a process quality indicator instead of a risk factor of poor outcome, at least considering the current limitations of the parameter.

Airway Management in the Critically Ill Patient

Purpose of Review

This paper will evaluate the recent literature and best practices in airway management in critically ill patients.

Recent Findings

Cardiac arrest remains a common complication of intubation in these high-risk patients. Patients with desaturation or peri-intubation hypotension are at high risk of cardiac arrest, and each of these complications have been reported in up to half of all intubations in critically ill patient populations.

Summary

There have been significant advances in preoxygenation and devices available for performing laryngoscopy and rescue oxygenation. However, the risk of cardiovascular collapse remains concerningly high with few studies to guide therapeutic maneuvers to reduce this risk.

Intubation Practices and Adverse Peri-intubation Events in Critically Ill Patients From 29 Countries

IMPORTANCE

Tracheal intubation is one of the most commonly performed and high-risk interventions in critically ill patients. Limited information is available on adverse peri-intubation events.

OBJECTIVE

To evaluate the incidence and nature of adverse peri-intubation events and to assess current practice of intubation in critically ill patients.

DESIGN, SETTING, AND PARTICIPANTS

The International Observational Study to Understand the Impact and Best Practices of Airway Management in Critically Ill Patients (INTUBE) study was an international, multicenter, prospective cohort study involving consecutive critically ill patients undergoing tracheal intubation in the intensive care units (ICUs), emergency departments, and wards, from October 1, 2018, to July 31, 2019 (August 28, 2019, was the final follow-up) in a convenience sample of 197 sites from 29 countries across 5 continents.

EXPOSURES

Tracheal intubation.

MAIN OUTCOMES AND MEASURES

The primary outcome was the incidence of major adverse peri-intubation events defined as at least 1 of the following events occurring within 30 minutes from the start of the intubation procedure: cardiovascular instability (either: systolic pressure <65 mm Hg at least once, <90 mm Hg for >30 minutes, new or increase need of vasopressors or fluid bolus >15 mL/kg), severe hypoxemia (peripheral oxygen saturation <80%) or cardiac arrest. The secondary outcomes included intensive care unit mortality.

RESULTS

Of 3659 patients screened, 2964 (median age, 63 years; interquartile range [IQR], 49-74 years; 62.6% men) from 197 sites across 5 continents were included. The main reason for intubation was respiratory failure in 52.3% of patients, followed by neurological impairment in 30.5%, and cardiovascular instability in 9.4%. Primary outcome data were available for all patients. Among the study patients, 45.2% experienced at least 1 major adverse peri-intubation event. The predominant event was cardiovascular instability, observed in 42.6% of all patients undergoing emergency intubation, followed by severe hypoxemia (9.3%) and cardiac arrest (3.1%). Overall ICU mortality was 32.8%.

CONCLUSIONS AND RELEVANCE

In this observational study of intubation practices in critically ill patients from a convenience sample of 197 sites across 29 countries, major adverse peri-intubation events-in particular cardiovascular instability-were observed frequently.

Evaluation and Management of the Physiologically Difficult Airway: Consensus Recommendations From Society for Airway Management

Multiple international airway societies have created guidelines for the management of the difficult airway. In critically ill patients, there are physiologic derangements beyond inadequate airway protection or hypoxemia. These risk factors contribute to the "physiologically difficult airway" and are associated with complications including cardiac arrest and death. Importantly, they are largely absent from international guidelines. Thus, we created management recommendations for the physiologically difficult airway to provide practical guidance for intubation in the critically ill. Through multiple rounds of in-person and telephone conferences, a multidisciplinary working group of 12 airway specialists (Society for Airway Management's Special Projects Committee) over a time period of 3 years (2016-2019) reviewed airway physiology topics in a modified Delphi fashion. Consensus agreement with the following recommendations among working group members was generally high with 80% of statements showing agreement within a 10% range on a sliding scale from 0% to 100%. We limited the scope of this analysis to reflect the resources and systems of care available to out-of-operating room adult airway providers. These recommendations reflect the practical application of physiologic principles to airway management available during the analysis time period.

Canadian Airway Focus Group updated consensus-based recommendations for management of the difficult airway: part 2. Planning and implementing safe management of the patient with an anticipated difficult airway

PURPOSE

Since the last Canadian Airway Focus Group (CAFG) guidelines were published in 2013, the published airway management literature has expanded substantially. The CAFG therefore re-convened to examine this literature and update practice recommendations. This second of two articles addresses airway evaluation, decision-making, and safe implementation of an airway management strategy when difficulty is anticipated.

SOURCE

Canadian Airway Focus Group members, including anesthesia, emergency medicine, and critical care physicians were assigned topics to search. Searches were run in the Medline, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL databases. Results were presented to the group and discussed during video conferences every two weeks from April 2018 to July 2020. These CAFG recommendations are based on the best available published evidence. Where high-quality evidence is lacking, statements are based on group consensus.

FINDINGS AND KEY RECOMMENDATIONS

Prior to airway management, a documented strategy should be formulated for every patient, based on airway evaluation. Bedside examination should seek predictors of difficulty with face-mask ventilation (FMV), tracheal intubation using video- or direct laryngoscopy (VL or DL), supraglottic airway use, as well as emergency front of neck airway access. Patient physiology and contextual issues should also be assessed. Predicted difficulty should prompt careful decision-making on how most safely to proceed with airway management. Awake tracheal intubation may provide an extra margin of safety when impossible VL or DL is predicted, when difficulty is predicted with more than one mode of airway management (e.g., tracheal intubation and FMV), or when predicted difficulty coincides with significant physiologic or contextual issues. If managing the patient after the induction of general anesthesia despite predicted difficulty, team briefing should include triggers for moving from one technique to the next, expert assistance should be sourced, and required equipment should be present. Unanticipated difficulty with airway management can always occur, so the airway manager should have a strategy for difficulty occurring in every patient, and the institution must make difficult airway equipment readily available. Tracheal extubation of the at-risk patient must also be carefully planned, including assessment of the patient's tolerance for withdrawal of airway support and whether re-intubation might be difficult.

Identification of the Physiologically Difficult Airway in the Pediatric Emergency Department

BACKGROUND

The risk factors for peri-intubation cardiac arrest in critically ill children are incompletely understood. The study objective was to derive physiologic risk factors for deterioration during tracheal intubation in a pediatric emergency department (PED).

METHODS

This was a retrospective cohort study of patients undergoing emergency tracheal intubation in a PED. Using the published literature and expert opinion, a multidisciplinary team developed high-risk criteria for peri-intubation arrest: 1) hypotension, 2) concern for cardiac dysfunction, 3) persistent hypoxemia, 4) severe metabolic acidosis (pH < 7.1), 5) post-return of spontaneous circulation (ROSC), and 6) status asthmaticus. We completed a structured review of the electronic health record for a historical cohort of patients intubated in the PED. The primary outcome was peri-intubation arrest. Secondary outcomes included tracheal intubation success rate, extracorporeal membrane oxygenation (ECMO) activation, and in-hospital mortality. We compared outcomes between patients meeting one or more versus no high-risk criteria.

RESULTS

Peri-intubation cardiac arrest occurred in 5.6% of patients who met at least one high-risk criterion compared to 0% in patients meeting none (5.6% difference, 95% confidence interval [CI] = 1.0 to 18.1, p = 0.028). Patients meeting at least one criterion had higher rates of any postintubation cardiac arrest in the PED (11.1% vs. 0%, 11.1% difference, 95% CI = 4.1 to 25.3, p = 0.0007), in-hospital mortality (25% vs. 2.3%, 22.7% difference, 95% CI = 11.0 to 38.9, p < 0.0001), ECMO activation (8.3% vs. 0%, 8.3% difference, 95% CI = 2.5 to 21.8, p = 0.004), and lower likelihood of first-pass intubation success (47.2% vs. 66.1%, -18.9% difference, 95% CI = -35.5 to -1.5, p = 0.038), respectively.

CONCLUSIONS

We have developed criteria that successfully identify physiologically difficult airways in the PED. Children with hypotension, persistent hypoxemia, concern for cardiac dysfunction, severe metabolic acidosis, status asthmaticus or who are post-ROSC are at higher risk for peri-intubation cardiac arrest and in-hospital mortality. Further multicenter investigation is needed to validate our findings.

Time to Loss of Preoxygenation in Emergency Department Patients

BACKGROUND

In patients requiring emergency rapid sequence intubation (RSI), 100% oxygen is often delivered for preoxygenation to replace alveolar nitrogen with oxygen. Sometimes, however, preoxygenation devices are prematurely removed from the patient prior to the onset of apnea, which can lead to rapid loss of preoxygenation.

OBJECTIVE

We sought to determine the elapsed time, on average, between removing the oxygen source and the loss of preoxygenation among non-critically ill patients in the emergency department (ED).

METHODS

We conducted a prospective, crossover study of non-critically ill patients in the ED. Each patient received two identical preoxygenation trials for 4 min using a non-rebreather mask with oxygen flow at flush rate and a nasal cannula with oxygen flow at 10 L/min. After each preoxygenation trial, patients underwent two trials in random order while continuing spontaneous breathing: 1) removal of both oxygen sources and 2) removal of non-rebreather mask with nasal cannula left in place. We defined loss of preoxygenation as an end-tidal oxygen (exhaled oxygen percentage; EtO₂) value < 70%. We measured EtO₂ breath by breath until loss of preoxygenation occurred.

RESULTS

We enrolled 42 patients, median age was 43 years (interquartile range [IQR] 30 to 54 years) and 72% were male. Median time to loss of preoxygenation was 20 s (IQR 17-25 s, 4.5 breaths) when all oxygen devices were removed, and 39 s (IQR 21-56 s, 8 breaths) when the nasal cannula was left in place.

CONCLUSIONS

In this population of non-critically ill ED patients, most had loss of preoxygenation after 5 breaths if all oxygen devices were removed, and after 8 breaths if a nasal cannula was left in place. These data suggest that during ED RSI, preoxygenation devices should be left in place until the patient is completely apneic.

High-Risk Airway Management in the Emergency Department. Part I: Diseases and Approaches

BACKGROUND

Successful airway management is critical to the practice of emergency medicine. Emergency physicians must be ready to optimize and prepare for airway management in critically ill patients with a wide range of physiologic challenges. Challenges in airway management commonly encountered in the emergency department are discussed using a pearl and pitfall discussion in this first part of a 2-part series.

OBJECTIVE

This narrative review presents an evidence-based approach to airway and patient management during endotracheal intubation in challenging cases that are commonly encountered in the emergency department.

DISCUSSION

Adverse events during emergent airway management are common, with postintubation cardiac arrest reported in as many as 1 in 25 intubations. Many of these adverse events can be avoided with the proper identification and understanding of the underlying physiology, preparation, and postintubation management. Patients with high-risk features including severe metabolic acidosis; shock and hypotension; obstructive lung disease; pulmonary hypertension, right ventricle failure, and pulmonary embolism; and severe hypoxemia must be managed with airway expertise.

CONCLUSIONS

This narrative review discusses the pearls and pitfalls of commonly encountered physiologic high-risk intubations with a focus on the emergency clinician.

Aerosol Risk with Noninvasive Respiratory Support in Patients with COVID-19

Objectives

This study evaluates aerosol production with high‐flow nasal cannula (HFNC) and noninvasive positive pressure ventilation (NIPPV) compared to 6 L/min by low‐flow nasal cannula.

Methods

Two healthy volunteers were randomized to control (6 L/min by low‐flow nasal cannula), NIPPV, or HFNC using block randomization. NIPPV conditions were studied using continuous positive airway pressures of 5, 10, and 15 cm H₂O with an FiO₂ of 1.0 delivered via full‐face mask. HFNC conditions included flow rates of 30 and 40 L/min with an FiO₂ of 1.0 with and without coughing. HFNC and low‐flow nasal cannula conditions were repeated with and without participants wearing a surgical mask. Six aerosol sizes (0.3, 1.0, 2.5, 5, and 10 µm) and total aerosol mass were measured at 2 and 6 ft from the participant's nasopharynx.

Results

There was no significant difference in aerosol production between either HFNC or NIPPV and control. There was also no significant difference with the use of a procedural mask over the HFNC. There was significant variation between the 2 participants, but in neither case was there a difference compared to control. There was an aerosol‐time trend, but there does not appear to be a difference between either flow rate, pressure, or control. Furthermore, there was no accumulation of total aerosol particles over the total duration of the experiment in both HFNC and NIPPV conditions.

Conclusions

HFNC and NIPPV did not increase aerosol production compared to 6 L/min by low‐flow nasal cannula in this experiment involving healthy volunteers.