Secondary confirmation of endotracheal tube position by ultrasound image

Basic concepts in the use of thoracic and lung ultrasound

PURPOSE OF REVIEW

Recent advances were made in the field of point-of-care ultrasound (POCUS). Thoracic and lung ultrasound have become a rapid and accurate method of diagnosis of hypoxic diseases. The purpose of this article is to review the recent literature on POCUS, emphasizing on its use in the operating room.

RECENT FINDINGS

Many international critical care societies published guidelines on the use of ultrasound in the installation of central venous access. More recently, evidenced-based guidelines on the use of POC lung ultrasound were published. Lung ultrasound has shown its superiority over conventional chest radiography in the diagnosis of many disorders of significant importance in anesthesiology, particularly the pneumothorax.

SUMMARY

POC thoracic and lung ultrasound is used in many critical medicine fields. The aim of this review is to describe the basic lung ultrasound technique and the knowledge required in order to diagnose and treat the hypoxic patient. Emphasis is on disorder such as pleural effusion, alveolar interstitial disease, as well as pneumothorax, which is of particular importance in the field of anesthesiology.

Novel device (AirWave) to assess endotracheal tube migration: a pilot study

INTRODUCTION

Little is known about endotracheal tube (ETT) migration during routine care among critically ill patients. AirWave is a novel device that uses sonar waves to measure ETT migration and obstructions in real time. The aim of the present study is to assess the accuracy of the AirWave to evaluate ETT migration. In addition, we determined the degree of variation in ETT position and tested whether more pronounced migration occurs in specific clinical scenarios.

METHODS

After institutional review board approval, we included mechanically ventilated patients from February 2012 to May 2012. A chest radiography (CXR) was obtained at baseline and 24 hours when clinically indicated. The ETT distance at the lips was recorded at baseline and every 4 hours. The AirWave system continuously recorded ETT position changes from baseline, and luminal obstructions.

RESULTS

A total of 42 patients (age: 61 [SD ±13] years, men: 52%) were recruited. A total of 19 patients had measurements of ETT migration at 24 hours by the 3 methodologies used in this study. The mean (SD) of the ETT migration at 24 hours was +0.04 (1.2), -0.42 (0.7) and +0.34 (1.81) cm when measured by portable CXR, ETT distance at the teeth and AirWave device, respectively. Bland-Altman analysis of tube migration at 24 hours comparing the AirWave with CXR readings showed a bias of 0.1 cm with 95% limit of agreement of -3.8 and +4.3 cm. Comparison of tube migration at 24 hours determined by AirWave with ETT distance at the lips revealed a bias of -0.4 with 95% limit of agreement -3.7 to +3 cm, similar to the values observed between CXR and ETT distance at the lips (bias of -0.3 cm, 95% limit of agreement of -3.4 to +2.8 cm). Factors associated with ETT migration at 24 hours were ETT size and initial measurement from ETT tip to carina by portable CXR. AirWave detected in eight patients some degree of ETT obstruction (30% ± 9.6%) that resolved with prompt ETT catheter suction.

CONCLUSIONS

The AirWave may provide useful information regarding ETT migration and obstruction in real time.

Dynamic anatomic relationship of the esophagus and trachea on sonography: implications for endotracheal tube confirmation in children

OBJECTIVES

Sonographic visualization of an empty esophagus to confirm endotracheal tube placement during intubation may be more reliable than identifying an endotracheal tube within the trachea. Our objective was to determine the frequency in which the normal empty esophagus can be identified at or below the level of the cricoid ring in children.

METHODS

A prospective cohort of children and young adults presenting to the emergency department were examined by sonography to determine the dynamic anatomic relationship of the trachea and esophagus at or below the level of the cricoid ring. For children with the esophagus behind or partially behind the trachea, cricoid pressure was applied using a linear array transducer to visualize the presence of lateral sliding of the esophagus from behind the trachea.

RESULTS

A total of 55 patients 21 years or younger were examined; 51% (28) were male. Sixty-two percent (34) had esophagi positioned partially to the left of the cricoid ring, 20% (11) completely to the left of the cricoid ring, 16% (9) behind the cricoid ring, and 2% (1) partially to the right of the cricoid ring. When cricoid pressure was applied using the ultrasound transducer, the esophagus was visualized lateral to the trachea in all patients (54 to the left and 1 to the right; n = 55 of 55; 95% confidence interval, 94%-100%).

CONCLUSIONS

With cricoid pressure applied using a linear transducer, the esophagus was visualized lateral to the trachea in all children and young adults. Visualizing an empty esophagus by point-of-care sonography may be feasible to confirm endotracheal tube placement by a process of elimination.

Ultrasound confirmation of endotracheal tube position in neonates

BACKGROUND

The placement of the endotracheal tube (ETT) in neonates is a challenging procedure that currently requires timely confirmation of tip placement by radiographic imaging.

OBJECTIVE

We sought to determine if bedside ultrasound (US) could demonstrate ETT tip location in preterm and term newborns and offer a quick alternative method of ETT positioning.

METHODS

We conducted a prospective pilot study of 30 newborns admitted to the UC San Diego Medical Center who had their ETT placement confirmed by chest radiographs. After a radiograph, each infant had a US exam with a 13-MHz linear transducer on a portable US machine. To assist localization, gentle longitudinal movement of the ETT of less than 0.5 cm was performed. Measurements from the tip of the ETT tip to the carina were made on chest radiograph and midsagittal US images.

RESULTS

Study infants had a mean gestational age of 30.2 ± 4.9 (SD) weeks and mean birth weight of 1,595.2 ± 862 g. US images were taken a mean 2.9 ± 2.2 h after radiographs. Data from 2 infants were excluded for poor radiograph image quality and extreme outlier values. The ETT was visualized by US in all newborns examined. We observed a good correlation between ETT tip-to-carina distance on US and radiograph (r(2) = 0.68) with minimal bias. Each study took less than 5 min to obtain without any clinical deterioration.

CONCLUSIONS

Bedside US can visualize the anatomic position of the ETT position in preterm and term infants but further validation is required before routine clinical implementation.

Ultrasonographic lung sliding sign in confirming proper endotracheal intubation during emergency intubation

AIM OF STUDY

Unrecognized one-lung intubations (also known as main-stem intubation) can lead to hypoventilation, atelectasis, barotrauma, and even patient death. Many traditional methods can be employed to detect one-lung intubation; however, each of these methods has limitations and is not consistently reliable in emergency settings. This study aimed to assess the accuracy and timeliness of ultrasound to confirm proper endotracheal intubation.

METHODS

This was a prospective, single-center, observational study conducted at the emergency department of a national university teaching hospital. Patients received emergency tracheal intubation because of respiratory failure or cardiac arrest. After intubation, bedside ultrasound was performed with a transducer placed on the chest bilaterally at the mid-axillary line, to identify lung sliding over the lungs bilaterally during ventilation. Chest radiography was used as the criterion standard for confirmation of endotracheal tube position.

RESULTS

One hundred and fifteen patients needing tracheal intubation were included, and nine (7.8%) had one-lung intubations. The overall accuracy of ultrasound to confirm proper endotracheal intubation was 88.7% (95% confidence interval (CI): 81.6-93.3%). The positive predictive value was 94.7% (95% CI: 87.1-97.9%) in the non-cardiac-arrest group and 100% (95% CI: 87.1-100.0%) in the cardiac-arrest group. The median operating time of ultrasound was 88 s (interquartile range [IQR]: 55.0, 193.0), and of chest radiography was 1349 s (IQR: 879.0, 2221.0) post intubation.

CONCLUSIONS

In this study, the positive predictive value of bilateral lung sliding in confirming proper endotracheal intubation was high, especially among patients with cardiac arrest. Considerable time advantage of ultrasound over chest radiography was demonstrated.

Ultrasonography in the management of the airway

In this study, it is described how to use ultrasonography (US) for real-time imaging of the airway from the mouth, over pharynx, larynx, and trachea to the peripheral alveoli, and how to use this in airway management. US has several advantages for imaging of the airway - it is safe, quick, repeatable, portable, widely available, and it must be used dynamically for maximum benefit in airway management, in direct conjunction with the airway management, i.e. immediately before, during, and after airway interventions. US can be used for direct observation of whether the tube enters the trachea or the esophagus by placing the ultrasound probe transversely on the neck at the level of the suprasternal notch during intubation, thus confirming intubation without the need for ventilation or circulation. US can be applied before anesthesia induction and diagnose several conditions that affect airway management, but it remains to be determined in which kind of patients the predictive value of such an examination is high enough to recommend this as a routine approach to airway management planning. US can identify the croicothyroid membrane prior to management of a difficult airway, can confirm ventilation by observing lung sliding bilaterally and should be the first diagnostic approach when a pneumothorax is suspected intraoperatively or during initial trauma-evaluation. US can improve percutaneous dilatational tracheostomy by identifying the correct tracheal-ring interspace, avoiding blood vessels and determining the depth from the skin to the tracheal wall.

Temporal comparison of ultrasound vs. auscultation and capnography in verification of endotracheal tube placement

BACKGROUND

This study compared the time consumption of bilateral lung ultrasound with auscultation and capnography for verifying endotracheal intubation.

METHODS

A prospective, paired, and investigator-blinded study carried out in the operating theatre. Twenty-five adult patients requiring endotracheal intubation were included. During intubation, transtracheal ultrasound was performed to visualize passage of the endotracheal tube. During bag ventilation, bilateral lung ultrasound was performed for the detection of lung sliding as a sign of ventilation simultaneous with capnography and auscultation of the epigastrium and chest. Primary outcome measure was time difference to confirmed endotracheal intubation between ultrasound and auscultation alone. Secondary outcome measure was time difference between ultrasound and auscultation combined with capnography.

RESULTS

Both methods verified endotracheal tube placement in all patients. In 68% of patients, endotracheal tube placement was visualized by real-time transtracheal ultrasound. Comparing ultrasound with the combination of auscultation and capnography, there was a significant difference between the two methods. Median time for ultrasound was 40 s [interquartile range (IQR) 35-48 s] vs. 48 s (IQR 45-53 s), P < 0.0001. Mean difference was -7.1 s in favour of ultrasound [95% confidence interval (CI) -9.4--4.8 s]. No significant difference was found between ultrasound compared with auscultation alone. Median time for auscultation alone was 42 s (IQR 37-47 s), P = 0.6, with a mean difference of -0.88 s in favour of ultrasound (95% CI -4.2-2.5 s).

CONCLUSIONS

Verification of endotracheal tube placement with ultrasound is as fast as auscultation alone and faster than the standard method of auscultation and capnography.

Tracheal rapid ultrasound exam (T.R.U.E.) for confirming endotracheal tube placement during emergency intubation

OBJECTIVES

This study aimed to assess the diagnostic accuracy and timeliness of using tracheal ultrasound to examine endotracheal tube placement during emergency intubation.

METHODS

This was a prospective, observational study, conducted at the emergency department of a national university teaching hospital. Patients received emergency intubation because of impending respiratory failure, cardiac arrest, or severe trauma. The tracheal rapid ultrasound exam (T.R.U.E.) was performed during emergency intubation with the transducer placed transversely at the trachea over the suprasternal notch. Quantitative waveform capnography was used as the criterion standard for confirmation of tracheal intubation. The main outcome was the concordance between the T.R.U.E. and the capnography.

RESULTS

A total of 112 patients were included in the analysis, and 17 (15.2%) had esophageal intubations. The overall accuracy of the T.R.U.E. was 98.2% (95% confidence interval [CI]: 93.7-99.5%). The kappa (κ) value was 0.93 (95% CI: 0.84-1.00), indicating a high degree of agreement between the T.R.U.E. and capnography. The sensitivity, specificity, positive predictive value, and negative predictive value of the T.R.U.E. were 98.9% (95% CI: 94.3-99.8%), 94.1% (95% CI: 73.0-99.0%), 98.9% (95% CI: 94.3-99.8%) and 94.1% (95% CI: 73.0-99.0%). The median operating time of the T.R.U.E. was 9.0s (interquartile range [IQR]: 6.0, 14.0).

CONCLUSIONS

The application of the T.R.U.E. to examine endotracheal tube placement during emergency intubation is feasible, and can be rapidly performed.

Use of sonography for rapid identification of esophageal and tracheal intubations in adult patients

OBJECTIVES

The aim of this study was to investigate the usefulness of sonography for verifying tracheal tube placement within 3 seconds in adult surgical patients.

METHODS

This was a blinded prospective randomized study. The anesthesiologist placed the tracheal tube randomly in the trachea (n = 75) or in the esophagus (n = 75) with direct laryngoscopy. A sonographer identified all tracheal and esophageal intubations. The transducer was placed transversely on the neck just superior to the suprasternal notch. The position of the tracheal tube was determined by the sonographer within 3 seconds of tracheal tube placement in the trachea or in the esophagus.

RESULTS

We successfully identified 150 correct tracheal tube placements in tracheas and esophagi, resulting in sensitivity of 100% (95% confidence interval, 84%-100%) and specificity of 100% (95% confidence interval, 84%-100%).

CONCLUSIONS

This investigation shows that sonography for confirming tracheal intubation is a fast and effective technique.

Ultrasound M-mode assessment of diaphragmatic kinetics by anterior transverse scanning in healthy subjects

The purpose of this study was to set an effective standardized method to assess diaphragmatic kinetics by ultrasound. Forty healthy volunteers were submitted to a B- and M-mode ultrasound study using a convex transducer positioned in the subcostal anterior area for transverse scanning. Ultrasound examination was completed in 38/40 cases (95%), spending on average <10 min for examination. The resting and forced diaphragmatic excursions were 18.4 ± 7.6 and 78.8 ± 13.3 mm, respectively, unrelated to demographic or anthropometric parameters: intraobserver variability on three successive measurements resulted in 6.0% and in 3.9%, respectively. An inexperienced sonographer completed the ultrasound examination in 37/40 cases, spending on average >15 min, with significant, although marginal, interobserver variability (31.9% and 14.7% for resting and forced diaphragmatic excursion, respectively). Bedside ultrasonography by an anterior subcostal transverse scanning on semi-recumbent patient proves to be a safe, feasible, reliable, fast, relatively easy and reproducible way to assess diaphragm movement.

Portable ultrasound for remote environments, part II: current indications

BACKGROUND

With recent advances in ultrasound technology, it is now possible to deploy lightweight portable imaging devices in the field. Techniques and studies initially developed for hospital use have been extrapolated out of the hospital setting in a wide variety of environments in an effort to increase diagnostic accuracy in austere or prehospital environments.

OBJECTIVES

This review summarizes current ultrasound applications used in out-of-hospital arenas and highlights existing evidence for such use. The diversity of applications and environments is organized by indication to better inform equipment selection as well as future directions for research and development.

DISCUSSION

Trauma evaluation, casualty triage, and assessment for pneumothorax, acute mountain sickness, and other applications have been studied by field medical teams. A wide range of outcomes have been reported, from alterations in patient care to determinations of accuracy compared to clinical judgment or other diagnostic modalities.

CONCLUSIONS

The use of lightweight portable ultrasound shows great promise in augmenting clinical assessment for field medical operations. Although some studies of diagnostic accuracy exist in this setting, further research focused on clinically relevant outcomes data is needed.

Confirmation of endotracheal intubation by combined ultrasonographic methods in the Emergency Department

OBJECTIVES

The objective of the present study was to investigate whether the combined use of transcricothyroid membrane ultrasonography and ultrasonographic evaluation for pleural sliding is useful for verifying endotracheal intubation in the ED.

METHODS

We performed a prospective clinical trial in the ED from January to July 2008. All patients enrolled in the present study had been admitted to the ED owing to severe airway problems. A linear probe was placed horizontally over the cricothyroid membrane (dynamic phase) during the intubation process. Endotracheal intubation was confirmed by ultrasonographic lung sliding. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated.

RESULTS

Thirty patients (17 men, 13 women; mean age 59.6 +/- 16.7 [SD] years) were enrolled in the study. Of the 30, 7 had a history of trauma. Four trauma patients were diagnosed with haemopneumothorax. The ratio of initial oesophageal-to-endotracheal intubation was 3:27. Sensitivity, specificity, PPV and NPV for endotracheal intubation were 96.3%, 100%, 100% and 75%, respectively. After verification by ultrasonographic lung sliding, sensitivity, specificity, PPV and NPV were each 100%.

CONCLUSIONS

The combination of transcricothyroid membrane ultrasonography and ultrasonographic lung-sliding evaluation could be useful in confirming endotracheal intubation in the ED.

Whole-body ultrasound in the intensive care unit: a new role for an aged technique

Management of critically ill patients requires rapid and safe diagnostic techniques. Ultrasonography has become an indispensable tool that supplements physical examination in the intensive care unit. It enables early recognition of neurological emergencies, assists the diagnosis of abdominal and lung pathologies, and provides real-time information on the cardiac performance of critically ill patients. Furthermore, it detects possible infectious sites and renders therapeutic invasive procedures more convenient and less complicated. Whole-body ultrasound in the hands of adequately trained intensivists has the ability to reinvigorate the physical examination, without subjecting the patient to excessive irradiation and the risks of transport.

Clinician performed resuscitative ultrasonography for the initial evaluation and resuscitation of trauma

BACKGROUND

Traumatic injury is a leading cause of morbidity and mortality in developed countries worldwide. Recent studies suggest that many deaths are preventable if injuries are recognized and treated in an expeditious manner - the so called 'golden hour' of trauma. Ultrasound revolutionized the care of the trauma patient with the introduction of the FAST (Focused Assessment with Sonography for Trauma) examination; a rapid assessment of the hemodynamically unstable patient to identify the presence of peritoneal and/or pericardial fluid. Since that time the use of ultrasound has expanded to include a rapid assessment of almost every facet of the trauma patient. As a result, ultrasound is not only viewed as a diagnostic test, but actually as an extension of the physical exam.

METHODS

A review of the medical literature was performed and articles pertaining to ultrasound-assisted assessment of the trauma patient were obtained. The literature selected was based on the preference and clinical expertise of authors.

DISCUSSION

In this review we explore the benefits and pitfalls of applying resuscitative ultrasound to every aspect of the initial assessment of the critically injured trauma patient.

Analytic Review: Confirmation of Endotracheal Tube Position: A Narrative Review

Endotracheal tube (ETT) insertion is the primary method of definitive airway protection and control in critically ill patients. Detection of ETT malposition in a timely fashion is crucial in both elective and emergent intubation. In this review, we describe classic tests and highlight several new technologies that may assist the practitioner in determining ETT position within the esophago-tracheal complex, namely ultrasonographic and impedance-based methods. Strengths and weaknesses of particular methods are highlighted. Although many physical examination maneuvers have been described, reliance on the physical examination alone is insufficient for confirmation. Touted methods that appear failsafe, such as direct visualization of the ETT traversing the vocal cords have limitations, especially when dealing in the emergency setting accompanying a difficult to visualize airway. While carbon dioxide detection is an excellent confirmatory method, it is not infallible. Esophageal detection devices are useful as an alternative means of confirmation. New methods such as ultrasonic location of the ETT show promise but require further study. The clinician performing ETT insertion should have multiple confirmation methods that allow the practitioner to adapt to a variety of clinical situations, depending on local costs and availability. Finally, when the clinician still has uncertainty, or multiple tests give conflicting results, the availability of bronchoscopy at the bedside to visualize the carina through the ETT is useful.

A prospective comparison of diaphragmatic ultrasound and chest radiography to determine endotracheal tube position in a pediatric emergency department

BACKGROUND

Investigators report endotracheal tube misplacement in up to 40% of emergent intubations. The standard elements of confirmation have significant limitations. Diaphragmatic ultrasound is a potentially viable addition to the confirmatory process. Our primary hypothesis is that ultrasound is equivalent to chest radiography in determining endotracheal tube position within the airway in emergent pediatric intubations.

METHODS

We enrolled a prospective, convenience sample from all intubated patients in our emergency department. The primary outcome was the agreement between diaphragmatic ultrasound and chest radiography for endotracheal tube position. On ultrasound, tracheal placement equaled bilateral diaphragmatic motion, bronchial placement equaled unilateral diaphragmatic motion, and esophageal placement equaled no or paradoxical diaphragmatic motion during delivery of positive pressure. Study sonographers were blind to radiographic results. Our secondary outcome was the timeliness of ultrasound versus chest radiography results. Our institutional review board approved this study with a waiver of informed consent.

RESULTS

One hundred twenty-seven patients were enrolled. In 24 (19%) patients, the endotracheal tube was in the mainstem bronchus on chest radiography. There were no esophageal intubations in the sample. Ultrasound and chest radiography agreed on endotracheal tube placement in 106 patients (94 tracheal and 12 mainstem), for an overall agreement of 0.83. The sensitivity of ultrasound for tracheal placement was 0.91. The specificity of ultrasound for mainstem intubation was 0.50. Thirty-four patients had a second ultrasound by a separate, blinded sonographer; 33 of 34 of the results of the second sonographer were in agreement with the initial sonogram, for an interrater agreement of 97%. Clinically useful chest radiography results took a median of 8 minutes longer to achieve than ultrasound results.

CONCLUSIONS

Diaphragmatic ultrasound was not equivalent to chest radiography for endotracheal tube placement within the airway. However, ultrasound results were timelier, detected more misplacements than standard confirmation alone, and were highly reproducible between sonographers.

Airway management in children: ultrasonography assessment of tracheal intubation in real time?

BACKGROUND

Pediatric tracheal intubation requires considerable expertise and can represent a challenge to many anesthesiologists. Confirmation of correct tracheal tube position relies on direct visualization or indirect measures, such as auscultation and capnography. These methods have varying sensitivity and specificity, especially in the infant and young child. Ultrasonography is noninvasive and is becoming more readily available to the anesthesiologist. In this study, we investigated the characteristic real-time ultrasonographic findings of the normal pediatric airway during tracheal intubation and its suitability for clinical use.

METHODS

Thirty healthy children with normal airways requiring tracheal intubation were studied. Ultrasonographic measurements of the pediatric airway during tracheal intubation under deep inhaled anesthesia were performed using a Sonosite Titan (Sonosite, Bothell, WA) scanner while recording characteristic images during this process. Correct tracheal tube placement was further confirmed using auscultation and satisfactory end-tidal capnography.

RESULTS

The mean (+/- sd) age of studied patients was 48 +/- 37 mo, weight was 19.7. +/- 8.6 kg and the sex ratio (m/f) was 1:2. Successful tracheal intubation was verified using the following criteria: 1) identification of the trachea and tracheal rings, 2) visualization of vocal cords, 3) widening of glottis as the tracheal tube passes through, and 4) tracheal tube position above carina and demonstration of movement of the chest wall visceroparietal pleural interface (i.e., sliding sign) after manual ventilation of the lungs. One esophageal intubation was readily recognized by visualization of the tube in the left paratracheal space.

CONCLUSION

This study describes characteristic ultrasonographic findings of the pediatric airway during tracheal intubation. It suggests that ultrasonography may be useful for airway management in children.

Ultrasound in the surgical intensive care unit

PURPOSE OF REVIEW

Critically ill patients are subjected to a variety of diagnostic and therapeutic procedures. It is desirable to make these interventions as timely, safe, and effective as possible. Bedside ultrasound and echocardiography are tools that allow for diagnosis of many conditions, without subjecting the patient to radiation, dye, and the risks of transport. In addition, ultrasound guidance of procedures may improve safety and efficacy. This review analyzes the literature on ultrasound and echocardiography use in the ICU.

RECENT FINDINGS

There is evidence supporting the use of bedside echocardiography and ultrasound for the diagnosis of chest, abdominal, and other pathologic conditions in the ICU. There is also evidence to support ultrasound guidance of vascular access and other procedures. There are multiple reports of novel uses of bedside echocardiography and ultrasound in the ICU.

SUMMARY

There is substantial literature supporting ultrasound and bedside limited echocardiography in the critical care setting. In addition, there are frequent reports of new applications for these technologies in the literature. The role of ultrasound and bedside limited echocardiography in the critical care setting is likely to expand in the future and become a part of daily care in every surgical intensive care unit.

Point-of-care sonographic detection of left endobronchial main stem intubation and obstruction versus endotracheal intubation

OBJECTIVE

Determining the correct position of endotracheal tubes in critically ill patients may be complicated by external factors such as noise, body habitus, and the need for ongoing resuscitation. Multiple detection techniques have been developed to determine the correct endotracheal tube position, recently including the use of sonography to evaluate lung expansion and diaphragmatic excursion. These techniques have also been applied to diagnosis of right endobronchial main stem intubation, which may be confused with a unilateral pneumothorax in some cases.

METHODS

We describe the sonographic findings in a case series of endobronchial main stem intubations and obstruction, highlighting the utility of this sonographic application. Previous literature and future applications are discussed.

RESULTS

Sonographic detection of the sliding lung sign, the lung pulse, and diaphragmatic excursion can accurately detect main stem bronchial intubation as well as bronchial obstruction.

CONCLUSIONS

Clinical use of lung sonography may decrease the need for chest radiography and may allow more rapid diagnosis of main stem intubation and bronchial obstruction.

Bedside ultrasound in pediatric emergency medicine

Bedside emergency ultrasound has been used by emergency physicians for >20 years for a variety of conditions. In adult centers, emergency ultrasound is routinely used in the management of victims of blunt abdominal trauma, in patients with abdominal aortic aneurysm and biliary disease, and in women with first-trimester pregnancy complications. Although its use has grown dramatically in the last decade in adult emergency departments, only recently has this tool been embraced by pediatric emergency physicians. As the modality advances and becomes more available, it will be important for primary care pediatricians to understand its uses and limitations and to ensure that pediatric emergency physicians have access to the proper training, equipment, and experience. This article is meant to review the current literature relating to emergency ultrasound in pediatric emergency medicine, as well as to describe potential pediatric applications.

Current Role of Emergency US in Patients with Major Trauma

In patients with major trauma, focused abdominal ultrasonography (US) often is the initial imaging examination. US is readily available, requires minimal preparation time, and may be performed with mobile equipment that allows greater flexibility in patient positioning than is possible with other modalities. It also is effective in depicting abnormally large intraperitoneal collections of free fluid, which are indirect evidence of a solid organ injury that requires immediate surgery. However, because US has poor sensitivity for the detection of most solid organ injuries, an initial survey with US often is followed by a more thorough examination with multidetector computed tomography (CT). The initial US examination is generally performed with a FAST (focused assessment with sonography in trauma) protocol. Speed is important because if intraabdominal bleeding is present, the probability of death increases by about 1% for every 3 minutes that elapses before intervention. Typical sites of fluid accumulation in the presence of a solid organ injury are the Morison pouch (liver laceration), the pouch of Douglas (intraperitoneal rupture of the urinary bladder), and the splenorenal fossa (splenic and renal injuries). FAST may be used also to exclude injuries to the heart and pericardium but not those to the bowel, mesentery, and urinary bladder, a purpose for which multidetector CT is better suited. If there is time after the initial FAST survey, the US examination may be extended to extra-abdominal regions to rule out pneumothorax or to guide endotracheal intubation, vascular puncture, or other interventional procedures.

Use of bedside ultrasonography for endotracheal tube placement in pediatric patients: a feasibility study

OBJECTIVE

The purpose of our study was to evaluate the usefulness of bedside ultrasonography in verifying endotracheal tube placement in the pediatric population.

METHODS

This study consisted of 2 phases. In phase I, subjects were examined while intubated and after extubation to determine the presence of the endotracheal tube by applying each of 2 ultrasound transducers to the cricothyroid membrane. In phase II, pediatric patients were examined in the emergency department during intubation or immediately after intubation to ascertain proper endotracheal tube placement by using bedside ultrasonography. These results were compared with the results obtained with a colorimetric end-tidal carbon dioxide detector and chest radiographs.

RESULTS

Forty-nine and 50 patients (age: 1 day to 17 years) were recruited in the first and second phases of the study, respectively. The endotracheal tube was detected in all 99 patients by using bedside ultrasonography. Two views were required to show accurately the presence of the endotracheal tube in the trachea. Visualization was obtained in all cases, although short necks and cervical collars made the procedure more challenging. The sniffing position allowed for the best acquisition of high-quality images. Our linear transducer provided the best images but, because of its size, it was not ideal when space was limited. Therefore, the curvilinear transducer was used exclusively for phase II. During phase II, the mean times to acquire bedside ultrasonographic images of the endotracheal tube through the cricothyroid membrane and to obtain a chest radiograph were 17.1 seconds and 14.0 minutes, respectively. In 3 cases, bedside ultrasonographic images proved to be invaluable when the colorimetric end-tidal carbon dioxide detector yielded false-negative or equivocal readings.

CONCLUSIONS

Bedside ultrasonography can be used to accurately and rapidly determine the presence of the endotracheal tube within the trachea in pediatric patients.

Clinician-performed focused sonography for the resuscitation of trauma

Traumatic death remains pandemic. The majority of preventable deaths occur early and are due to injuries or physiologic derangements in the airway, thoracoabdominal cavities, or brain. Ultrasound is a noninvasive and portable imaging modality that spans a spectrum between the physical examination and diagnostic imaging. It allows trained examiners to immediately confirm important syndromes and answer clinical questions. Newer technologies greatly increase the fidelity, accessibility, ease of use, and informatic manipulation of the results. The early bedside use of focused ultrasound as the initial imaging modality used to detect hemoperitoneum and hemopericardium in the resuscitation of the injured patient has become an accepted standard of care. Widespread dissemination of basic ultrasound skills and technology to facilitate this brings ultrasound to many resuscitative and critical care areas. Although not as widely appreciated, the focused use of ultrasound may also have a role in detecting hemothoraces and pneumothoraces, guiding airway management, and detecting increased intracranial pressure. Intensivists generally utilize a treating philosophy that requires the real-time integration of many divergent sources of information regarding their patients' anatomy and physiology. They are therefore positioned to take advantage of focused resuscitative ultrasound, which offers immediate diagnostic information in the early care of the critically injured.

Role of ultrasound in the airway management of critically ill patients

Ultrasound imaging of the upper airway in critically ill patients offers a number of attractive advantages compared with competitive imaging techniques or endoscopy. It is widely available, portable, repeatable, relatively inexpensive, pain-free, and safe. In this review article, I describe ultrasonographic anatomy of the upper respiratory organs and present the main potential applications of ultrasonography in airway management. The role of ultrasound in endotracheal tube placement, including preintubation assessment, verification of tube position, double-lumen intubation, and extubation outcome, are explained. Also, ultrasound-guided percutaneous tracheostomy, the role of ultrasound in using the laryngeal mask airway, and upper airway anesthesia are described.

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.

Pilot study to evaluate the accuracy of ultrasonography in confirming endotracheal tube placement

STUDY OBJECTIVE

Visualization of the vocal cords and end-tidal capnography are the usual standards in confirming endotracheal tube placement. Vocal cord visualization is, however, not always possible, and capnography is not 100% reliable and requires ventilation of the lungs to confirm placement. The goal of this study is to determine the accuracy of ultrasonography for detecting endotracheal tube placement into the trachea and esophagus in real time.

METHODS

This was a prospective, randomized, controlled study. Eligible patients were adults undergoing elective surgery requiring intubation. Exclusion criteria were a history of difficult intubation, abnormal airway anatomy, aspiration risk factors, and esophageal disease. Thirty-three patients were enrolled. After induction of anesthesia and neuromuscular blockade, the anesthesiologist placed the endotracheal tube in the trachea and esophagus in random order with direct laryngoscopy. During the intubations, a high-frequency, linear transducer was placed transversely on the neck at the suprasternal notch. Two emergency physicians, blinded to the order and performance of the intubations, independently recorded the location of the endotracheal tube according to the real-time ultrasonographic image. A 2-by-2 table was used to calculate sensitivity and specificity of the emergency physicians' ability to detect placement of the endotracheal tube.

RESULTS

For each physician, the sensitivity for identifying the first intubation as tracheal was 100% (95% confidence interval [CI] 77% to 100%) with a specificity of 100% (95% CI 82% to 100%). One endotracheal tube was unintentionally placed twice in the esophagus, but both tube placements were identified as esophageal by the emergency physicians.

CONCLUSION

In this pilot study, 2 emergency physicians experienced in ultrasonography accurately detected placement of endotracheal tubes during intubation with ultrasonography in select patients in the controlled environment of the operating room. Future studies should examine the use of ultrasonography to visualize endotracheal tube placement in real time by emergency physicians with less ultrasonographic training; use of the technique in the emergency department on a wider range of patients, including patients with difficult airways; and assessment of the utility of ultrasonography in confirmation of endotracheal tube position in already intubated patients.