Transtracheal 2-d ultrasound for identification of esophageal intubation

This prospective, blinded, observational, efficacy study is one of the first to evaluate ultrasound in detecting esophageal intubation, a significant source of morbidity and mortality. We utilized a convenience sample of patients undergoing elective surgery during July 2004 in an urban teaching hospital. Trained Emergency Physician sonographers performed transtracheal ultrasounds of intubations to identify esophageal intubation. In 35 of the 40 patients enrolled, there was intubation of the trachea, whereas esophageal intubation occurred in five patients. Sonographers correctly identified all five esophageal intubations, for a sensitivity of 100% (95% confidence interval [CI] 48–100). Ultrasound correctly identified 34 of 35 tracheal intubations and misidentified one resulting in a specificity of 97% (95% CI 90–100). It seems that transtracheal ultrasound may be an efficacious adjunct for detecting esophageal intubation.     

Confirmation of Endotracheal Tube Placement after Intubation Using the Ultrasound Sliding Lung Sign

Objectives: To evaluate the performance of the ultrasound (US) sliding lung sign as a predictor of endotracheal tube (ETT) placement. Many other tools and examination findings have been used to confirm ETT placement; erroneous placement of the ETT has even been confirmed by US. Methods: This was a laboratory study using fresh, recently dead cadavers. Cadavers were obtained at a medical school anatomy laboratory on the basis of availability during a four‐month period. Subjects who died from significant trauma or after thoracic surgery were excluded. A numerical randomization tool was used to direct where the tube would be placed on intubation. Laryngoscopy was performed, and the ETT was placed in the esophagus, in the trachea, or in the right main stem (RMS) bronchus. Placement was confirmed by direct laryngoscopic visualization of ETT passage through vocal cords or with fiber optic visualization, as needed. US images of the sliding lung sign, sliding of visceral and parietal pleura past each other, were taken on both sides of the chest at the mid axillary line during ventilation with an ambu bag. Two board‐certified emergency physicians with hospital credentialing in emergency US used a 4‐2 MHz micro‐convex transducer on a Sonosite 180 Plus for imaging. The sonologists were blinded to the location of the endotracheal tube and imaged and recorded their results individually. A positive sliding lung sign was taken to signify lung expansion with ventilation in a hemithorax. Endotracheal versus esophageal ETT placement, as well as tracheal versus RMS, was determined on the basis of sliding lung findings on both sides of the chest. Interpreter agreement, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and likelihood ratios (LHR) were calculated for tracheal (including RMS) versus esophageal, as well as main trachea versus RMS intubation. Results: Nine cadavers yielded 68 intubations. For esophageal versus tracheal (including RMS) intubation, sonologist 1 (S1) had a sensitivity of 95.4% (95% CI = 84.2% to 99.4%), a specificity of 100% (95% CI = 86.3% to 100%), an NPV of 92.6% (95% CI = 75.7% to 99.1%), and a PPV of 100% (95% CI = 91.4% to 100%) with an LHR of 0.05 (95% CI = 0.01 to 0.2) for a negative test. Sonologist 2 (S2) had a sensitivity of 100% (95% CI = 91.8% to 100%), a specificity of 100% (95% CI = 86.3% to 100%), an NPV of 100% (95% CI = 86.3% to 100%), and a PPV of 100% (95% CI = 91.8% to 100%); agreement was 97% (κ= 0.94; 95% CI = 0.7 to 1.2). In RMS versus tracheal, S1 had a sensitivity of 69.2% (95% CI = 48.2% to 85.7%), a specificity of 93.3% (95% CI = 68.1% to 99.8%), a PPV of 94.7% (95% CI = 73.9% to 99.9%), and an NPV of 63.6% (95% CI = 40.7% to 82.8%) with an LHR for a positive test of 10.4 (95% CI = 2.2 to 59.1) and of 0.4 (95% CI = 0.2 to 0.6) for negative test. S2 had a sensitivity of 78.6% (95% CI = 59.1% to 91.7%), a specificity of 100% (95% CI = 78.2% to 100%), a PPV of 100% (95% CI = 84.6% to 100%), NPV of 71.4% (95% CI = 47.8% to 88.7%), with an LHR for a negative test of 0.2 (95% CI = 0.1 to 0.4); agreement was 85.9% (κ= 0.6; 95% CI = 0.4 to 0.9). Conclusions: These results show that US imaging of the sliding lung sign in a cadaver model is an accurate method for confirmation of ETT placement. Further, the technique may have some utility in differentiating RMS bronchus from main tracheal intubations.     

Assessment of a New Method to Distinguish Esophageal from Tracheal Intubation by Measuring the Endotracheal Cuff Pressure in a Porcine Model

Objectives: With the knowledge of differences in anatomic structures between the trachea and the esophagus, the authors conducted an animal study to evaluate the usefulness of endotracheal cuff pressure in distinguishing endotracheal and esophageal intubations. Methods: Six swine were anesthetized and endotracheally intubated with 7.5-mm cuffed endotracheal tubes. The intubations were confirmed by fiber-optic bronchoscopy. Each pilot balloon was connected to a 10-mL syringe and a manometer via a three-way stopcock. The cuff pressures were measured for each 1-mL incremental filling of air (1–10 mL). After removal of the endotracheal tubes, each swine was then intubated with the same endotracheal tubes into its esophagus. The cuff pressures of the esophageal intubation were measured with the same procedure. The cuff pressures and the pressure–volume relationships in both intubations were compared. Results: The cuff pressure increased significantly in the esophageal intubation in comparison with the endotracheal intubation in all the comparisons from 1 mL to 10 mL (p = 0.028 for all Wilcoxon signed-rank tests). The slope of the pressure–volume curve of the cuff pressure was also significantly higher in the esophageal intubation during the inflation of the cuff on average (0.047 vs. 0.032 cm H₂O/mL; p = 0.001), particularly in the first 5 mL of air inflation. Conclusions: The cuff pressure in the esophageal intubation was significantly higher than that in the endotracheal intubation under the same inflated volume from 1 to 10 mL. This may provide the basis for an adjunctive, simple, rapid, and reliable method to verify endotracheal intubation.     

A Comparison of GlideScope Video Laryngoscopy Versus Direct Laryngoscopy Intubation in the Emergency Department

Objectives: The first‐attempt success rate of intubation was compared using GlideScope video laryngoscopy and direct laryngoscopy in an emergency department (ED). Methods: A prospective observational study was conducted of adult patients undergoing intubation in the ED of a Level 1 trauma center with an emergency medicine residency program. Patients were consecutively enrolled between August 2006 and February 2008. Data collected included indication for intubation, patient characteristics, device used, initial oxygen saturation, and resident postgraduate year. The primary outcome measure was success with first attempt. Secondary outcome measures included time to successful intubation, intubation failure, and lowest oxygen saturation levels. An attempt was defined as the introduction of the laryngoscope into the mouth. Failure was defined as an esophageal intubation, changing to a different device or physician, or inability to place the endotracheal tube after three attempts. Results: A total of 280 patients were enrolled, of whom video laryngoscopy was used for the initial intubation attempt in 63 (22%) and direct laryngoscopy was used in 217 (78%). Reasons for intubation included altered mental status (64%), respiratory distress (47%), facial trauma (9%), and immobilization for imaging (9%). Overall, 233 (83%) intubations were successful on the first attempt, 26 (9%) failures occurred, and one patient received a cricothyrotomy. The first‐attempt success rate was 51 of 63 (81%, 95% confidence interval [CI] = 70% to 89%) for video laryngoscopy versus 182 of 217 (84%, 95% CI = 79% to 88%) for direct laryngoscopy (p = 0.59). Median time to successful intubation was 42 seconds (range, 13 to 350 seconds) for video laryngoscopy versus 30 seconds (range, 11 to 600 seconds) for direct laryngoscopy (p < 0.01). Conclusions: Rates of successful intubation on first attempt were not significantly different between video and direct laryngoscopy. However, intubation using video laryngoscopy required significantly more time to complete.     

The sensitivity and specificity of transcricothyroid ultrasonography to confirm endotracheal tube placement in a cadaver model

Confirmation of endotracheal (ET) tube placement is critical when performing emergency airway management. No single confirmation strategy has emerged as ideal in all circumstances. Our objective in this study was to assess the sensitivity and specificity of a novel approach to verify endotracheal intubation using transcricothyroid ultrasonography (US). We performed a prospective, randomized double-blinded trial in a human cadaver model. A 7.5-MHz curvilinear probe was placed longitudinally over the cricothyroid membrane as cadavers were randomly intubated in either the trachea or esophagus in two phases: 1) as the intubation was being performed (dynamic) and, 2) after intubation had been completed (static). Volunteer emergency medicine (EM) residents, blinded to tube placement, assessed for esophageal vs. tracheal ET placement using dynamic and static US views. Sensitivity, specificity, positive predictive value, and negative predictive value for detecting esophageal ET placement with 95% confidence intervals were calculated. Seven EM residents made a total of 70 dynamic and 70 static assessments of ET position using transcricothyroid US. Dynamic assessment resulted in 97% sensitivity and 100% specificity for detecting esophageal ET placement. Static assessment resulted in only 51% sensitivity and 91% specificity. This pilot study suggests that dynamic transcricothyroid US is a potentially accurate method of confirming ET placement during the intubation process. Further investigation in live humans is warranted to validate these data.     

急诊内科危重病人气管插管时机与方法的探讨

目的:总结急诊内科病人气管插管的特点,分析其治疗效果,并探讨其插管时机、方法与转归。方法:根据病人在急诊科治疗情况,将病人分成三组。第Ⅰ组23例,系到医院前已临床死亡;第Ⅱ组30例,经抢救无效在急诊科死亡;第Ⅲ组30例,经抢救病人在急诊科存活,后转入病房或急诊留观。结果:第Ⅰ组病人经口气管插管,抢救平均30分钟,无一例心跳呼吸恢复;第Ⅱ组虽经急诊CPR,但呼吸功能不能恢复正常,或因其原发病未能控制,最终在急诊科死亡;第Ⅲ组病人经口插管13例,经鼻插管17例,6例病人在急诊留观治疗后出院,12例病人经ICU或病房住院治疗后基本痊愈出院,另12例最终死亡。结论:急诊科所遇垂危病人,多数需气管插管者是由内科医师首诊实施。正确的插管方法和较高的成功率是直接影响病人转归的重要因素。     

光学喉镜在急诊气管插管中的临床价值

目的:评价光学喉镜在急诊气管插管中的临床应用价值.方法:将我院2011年1月至2011年7月急诊气管插管的58例患者随机分为观察组(应用Truview/TMEVO2光学喉镜进行气管插管)和对照组(普通喉镜进行气管插管)各29例,比较两组插管效果.结果:两组喉镜使用力量比较、建立有效气道的时间均差异不明显(P＞0.05);观察组气道声门的暴露C/L分级、IDS评分、气管插管过程中SpO2的最低下降值及气管插管后并发症发生率明显优于对照组(P＜0.05).结论:光学喉镜应用于急诊气管插管中可增加气管插管的成功率,减少并发症.     

Complications of a Retrograde Intubation in a Trauma Patient

The authors report the case of an elder woman involved in a motor vehicle collision (MVC) requiring emergent intubation using the technique of retrograde intubation (RI). Since RI is a blind technique, potential complications arising from its use are numerous and may result in increased morbidity and mortality. Such was the case of this RI that involved incorrect placement of the endotracheal tube (ETT), resulting in suboptimal ventilation and increased morbidity. Additionally, this case illustrates how the failure to detect this error in multiple settings (ambulance, helicopter, emergency department) led to unnecessary and potentially deleterious procedures and significant delay in providing the basics of trauma care, oxygenation and ventilation. Although theoretical complications of RI have been addressed in the past, there have been very few published reports of actual complications. The emergency physician must be aware of difficult airways, options available to establish alternative airways, and methods to confirm appropriate placement of the ETT. The authors also discuss the indications, procedures, and complications involved in performing an RI.     

Out-of-hospital Rapid-sequence Induction for Intubation of the Pediatric Patient

Objective: To determine the effectiveness and morbidity of out-of-hospital rapid-sequence induction (RSI) for endotracheal intubation (ETI) in the pediatric population.
Methods: The medical records were retrospectively reviewed for a consecutive series of pediatric patients undergoing out-of-hospital RSI by flight paramedics from July 1990 through July 1994. Patient demographics, pharmacologic agents, ED arterial blood gas data, pulmonary complications, and RSI-related complications were abstracted.
Results: Forty patients (31 injured, 9 medical) with a mean age of 8.1 years (range 0.5–17 years) underwent out-of-hospital RSI. Indications for intubation included hyperventilation ( n = 20), combativeness ( n = 16), apnea ( n = 5), and unknown ( n = 5). Intubation mishaps occurred in 13 patients (33%); these included multiple attempts ( n = 9), aspiration ( n = 8), and esophageal intubation ( n = 1). The success rate of ETI was 97.5% (one failed attempt). Hemodynamic side effects occurred in three patients (8%); all three had bradycardia, with one developing hypotension. Bradycardia was associated with failure to pretreat with atropine (p < 0.05). Sixteen pulmonary complications, seven pneumonia (18%) and nine atelectasis (22.5%), occurred in 13 patients within the first ten hospital days. Intubation mishaps were not associated with pulmonary complications. There were six deaths, none associated with RSI.
Conclusions: 1) Rapid-sequence induction is an effective method for obtaining airway control in the critically ill pediatric patient. 2) Intubation mishaps did not influence the rate of pulmonary complications. 3) Omission of atropine was associated with bradycardia during RSI in pediatric patients.     

Human Patient Simulation Is Effective for Teaching Paramedic Students Endotracheal Intubation

Objectives: The primary purpose of this study was to determine whether the endotracheal intubation (ETI) success rate is different among paramedic students trained on a human patient simulator versus on human subjects in the operating room (OR). Methods: Paramedic students (n= 36) with no prior ETI training received identical didactic and mannequin teaching. After randomization, students were trained for ten hours on a patient simulator (SIM) or with 15 intubations on human subjects in the OR. All students then underwent a formalized test of 15 intubations in the OR. The primary outcome was the rate of successful intubation. Secondary outcomes were the success rate at first attempt and the complication rate. The study was powered to detect a 10% difference for the overall success rate (α= 0.05, β= 0.20). Results: The overall intubation success rate was 87.8% in the SIM group and 84.8% in the OR group (difference of 3.0% [95% confidence interval {CI} =?4.2% to 10.1%; p = 0.42]). The success rate on the first attempt was 84.4% in the SIM group and 80.0% in the OR group (difference of 4.4% [95% CI =?3.4% to 12.3%; p = 0.27]). The complication rate was 6.3% in the SIM group and 4.4% in the OR group (difference of 1.9% [95% CI =?2.9% to 6.6%; p = 0.44]). Conclusions: When tested in the OR, paramedic students who were trained in ETI on a simulator are as effective as students who trained on human subjects. The results support using simulators to teach ETI.     

Ultrasound Image Quality Comparison between an Inexpensive Handheld Emergency Department (ED) Ultrasound Machine and a Large Mobile ED Ultrasound System

Questions have been raised regarding image quality (IQ) provided by portable ultrasound (US) machines. OBJECTIVES: To determine if a difference exists between images obtained with a common portable US machine and those obtained with a more expensive, larger US machine when comparing typical views used by emergency physicians. METHODS: The authors performed a cross-sectional, blinded comparison of images from similar sonographic windows obtained on healthy models using a SonoSite 180 Plus and a General Electric (GE) 400 US machine. Both machines were optimized by company representatives. Images obtained included typical abdominal and vascular applications using the abdominal and linear transducers on each machine. All images were printed on identical high-resolution printers and then digitized using a bitmap format at 300 dots-per-inch resolution (RES). Images were then cropped, masked, and placed into random order comparing each view per model by a commercial Web design company (loracs.com). Three credentialed emergency physician sonologists, blinded to machine type, rated each image pair for RES, detail (DET), and total IQ as previously defined in the literature using a ten-point Likert scale; 10 was the best rating for each category. Paired t-test, 95% confidence intervals (95% CIs), and interobserver correlation were calculated. RESULTS: A total of 49 image pairs were evaluated. Mean GE 400 RES, DET, and IQ scores were 6.8, 6.8, and 6.6, respectively. Corresponding SonoSite means were 6.3, 6.3, and 6.0, respectively. The difference of 0.5 (95% CI = 0.13 to 1.1) for DET was not statistically significant (p = 0.06). The differences of 0.5 (95% CI = 0.1 to 1.1) and 0.6 (95% CI = 0.2 to 1.2) for RES and IQ were statistically significant, with p = 0.01 and 0.01. There was good interobserver agreement (kappa = 0.71; 95% CI = 0.67 to 0.78). CONCLUSIONS: A statistically significant difference was seen between GE 400 and SonoSite in IQ and RES, but not DET.