Background

Hospitalization for angioedema has increased since the introduction of angiotensin-converting enzyme (ACE) inhibitors for the treatment of hypertension. There are as many as 108,000 emergency department (ED) visits annually for angioedema. It can lead to critical airway obstruction and the need for intubation.

Importance

The intubation of a patient with severe angioedema can be extremely difficult because of swelling and distortion of airway anatomy, as well as pooling of airway secretions. Although described for cases outside of the ED, there are few descriptions of the methods, success rates, and complications of emergency airway management of angioedema in the ED.

Goals of This Investigation

We sought to characterize the methods, course, and outcomes of emergency airway management for patients treated for severe angioedema in our institution.

Study Design

We performed a retrospective, observational study, using video review as our primary method of data collection. This study was approved by our local institutional review board.

Setting

This study was conducted in Hennepin County Medical Center, a high-volume urban Level I trauma center treating approximately 100,000 patients per year. The ED is the setting for approximately 1,000 intubations per year. Emergency physicians manage all airways in our ED. Senior emergency medicine residents (postgraduate year 3 or higher) perform the majority of intubations under the supervision of the attending emergency physician. During the study period, there was no protocol for patients with difficult airways or angioedema.

Selection of Participants

Using the electronic medical record system (Epic Systems, Verona, WI), we identified all adults older than 17 years and with an ED or hospital diagnosis of angioedema ( International Classification of Diseases, Ninth Revision code 995.1) who underwent intubation in the ED between November 2007 and June 2015.

Methods of Measurement

We performed a structured review of resuscitation room videos recorded for each patient case. Critically ill or injured patients receive care in a 4-bay stabilization room. Each bay has 3 ceiling-mounted video cameras activated by motion sensors. Automated software combines the video streams with output from the patient cardiac and vital sign monitor, as well as audio recording of the room. The videos are stored on a secure database and are used for peer review and quality assurance purposes.

Both authors independently reviewed all selected videos, recording observations on a structured data collection form. Data points were defined by both investigators a priori, with refinement after review of the first 3 videos. One investigator (B.E.D.) recorded all data entry into Excel (version 14.0; Microsoft, Redmond, WA). Both investigators resolved discrepancies by consensus, including rereview of the relevant videos.

The medical record was used to identify patient demographics, ACE-inhibitor use, medications administered in the ED, and ED course before patient placement in the resuscitation bay.

Outcome Measures

Collected data included patient demographics, medications administered to facilitate intubation, the use of fiberoptic laryngoscopy before intubation, the course and methods of intubation, and complications of intubation. Elapsed times included time from ED arrival to start of intubation attempt, the duration of the first method, and time from the first attempt until successful intubation.

An intubation method was defined as the use of a single intubation approach (eg, blind nasal intubation, fiberoptic nasal intubation), without an intervening change to a different approach, regardless of the number of discrete attempts with that method. We defined the start of an airway attempt as the point at which the airway equipment (laryngoscope blade, oral intubating airway, endotracheal tube, or fiberoptic scope) entered the mouth or nose. We defined the end of an airway attempt as the point at which all airway equipment was removed from the patient, the method was changed (eg, from blind to fiberoptic nasal intubation), or the endotracheal tube was attached to a bag-valve device after successful intubation.

A patient was considered to have ACE inhibitor angioedema if the discharge summary stated that an ACE inhibitor was the most likely cause of angioedema. We were unable to assess the location and severity of angioedema because the overhead videos did not allow a detailed assessment of intraoral swelling, images from the video laryngoscopes were not routinely recorded, and descriptions in the medical record were not sufficiently detailed for most patients. Defined complications included hypoxemia (SpO ₂ less than 90% and SpO ₂ less than 90% for more than 60 seconds), esophageal intubation, epistaxis, vomiting, and hypotension (systolic blood pressure less than 90 mm Hg). Esophageal intubation was defined as advancement of the endotracheal tube into the esophagus with subsequent performance of bag-valve-mask ventilation before removal; if the endotracheal tube was passed into the esophagus during an attempt without bag-valve-mask ventilation, it was not considered to be an esophageal intubation. Epistaxis was defined as visible bleeding from either naris. We defined aspiration pneumonia as an infiltrate on chest radiography within 24 hours of admission that was believed by the treating physician to be a result of aspiration.

If a data point was unavailable or unclear from the video, it was considered to be missing for that subject.

Primary Data Analysis

We excluded all patients with missing videos. We analyzed the data with descriptive techniques. We used Stata (version 12.1; StataCorp, College Station, TX) for all data analyses.

Study Design

We performed a retrospective, observational study, using video review as our primary method of data collection. This study was approved by our local institutional review board.

Setting

This study was conducted in Hennepin County Medical Center, a high-volume urban Level I trauma center treating approximately 100,000 patients per year. The ED is the setting for approximately 1,000 intubations per year. Emergency physicians manage all airways in our ED. Senior emergency medicine residents (postgraduate year 3 or higher) perform the majority of intubations under the supervision of the attending emergency physician. During the study period, there was no protocol for patients with difficult airways or angioedema.

Selection of Participants

Using the electronic medical record system (Epic Systems, Verona, WI), we identified all adults older than 17 years and with an ED or hospital diagnosis of angioedema ( International Classification of Diseases, Ninth Revision code 995.1) who underwent intubation in the ED between November 2007 and June 2015.

Methods of Measurement

We performed a structured review of resuscitation room videos recorded for each patient case. Critically ill or injured patients receive care in a 4-bay stabilization room. Each bay has 3 ceiling-mounted video cameras activated by motion sensors. Automated software combines the video streams with output from the patient cardiac and vital sign monitor, as well as audio recording of the room. The videos are stored on a secure database and are used for peer review and quality assurance purposes.

Both authors independently reviewed all selected videos, recording observations on a structured data collection form. Data points were defined by both investigators a priori, with refinement after review of the first 3 videos. One investigator (B.E.D.) recorded all data entry into Excel (version 14.0; Microsoft, Redmond, WA). Both investigators resolved discrepancies by consensus, including rereview of the relevant videos.

The medical record was used to identify patient demographics, ACE-inhibitor use, medications administered in the ED, and ED course before patient placement in the resuscitation bay.

Outcome Measures

Collected data included patient demographics, medications administered to facilitate intubation, the use of fiberoptic laryngoscopy before intubation, the course and methods of intubation, and complications of intubation. Elapsed times included time from ED arrival to start of intubation attempt, the duration of the first method, and time from the first attempt until successful intubation.

An intubation method was defined as the use of a single intubation approach (eg, blind nasal intubation, fiberoptic nasal intubation), without an intervening change to a different approach, regardless of the number of discrete attempts with that method. We defined the start of an airway attempt as the point at which the airway equipment (laryngoscope blade, oral intubating airway, endotracheal tube, or fiberoptic scope) entered the mouth or nose. We defined the end of an airway attempt as the point at which all airway equipment was removed from the patient, the method was changed (eg, from blind to fiberoptic nasal intubation), or the endotracheal tube was attached to a bag-valve device after successful intubation.

A patient was considered to have ACE inhibitor angioedema if the discharge summary stated that an ACE inhibitor was the most likely cause of angioedema. We were unable to assess the location and severity of angioedema because the overhead videos did not allow a detailed assessment of intraoral swelling, images from the video laryngoscopes were not routinely recorded, and descriptions in the medical record were not sufficiently detailed for most patients. Defined complications included hypoxemia (SpO ₂ less than 90% and SpO ₂ less than 90% for more than 60 seconds), esophageal intubation, epistaxis, vomiting, and hypotension (systolic blood pressure less than 90 mm Hg). Esophageal intubation was defined as advancement of the endotracheal tube into the esophagus with subsequent performance of bag-valve-mask ventilation before removal; if the endotracheal tube was passed into the esophagus during an attempt without bag-valve-mask ventilation, it was not considered to be an esophageal intubation. Epistaxis was defined as visible bleeding from either naris. We defined aspiration pneumonia as an infiltrate on chest radiography within 24 hours of admission that was believed by the treating physician to be a result of aspiration.

If a data point was unavailable or unclear from the video, it was considered to be missing for that subject.

Primary Data Analysis

We excluded all patients with missing videos. We analyzed the data with descriptive techniques. We used Stata (version 12.1; StataCorp, College Station, TX) for all data analyses.