The addition of a brief ultrasound examination to clinical assessment increases the ability to confirm placement of double-lumen endotracheal tubes

Comparison of lung ultrasound technique <em>versus</em> clinical method to evaluate the accuracy of size and placement of left endobronchial double lumen tube in patients undergoing elective thoracic surgery: a prospective observational study

Anthropometric measurements like height and gender have been frequently found to be inaccurate in prediction of size of double lumen tube (DLT). A tracheal ultrasonography (TUS) is a technique that can be used to predict the size of DLT and its correct placement for lung isolation. We aim to check the accuracy of ultrasound over clinical methods. This prospective study included 68 patients undergoing elective thoracic surgery requiring one-lung ventilation (OLV) with DLT. The groups were assessed for the size of DLT by either anthropometric measurement using height and gender (Group C) or ultrasound method (Group U). Further, the accuracy of placement of DLT was assessed through, either lung auscultation in group C or various ultrasonographic and ventilatory parameters such as lung isolation in the first attempt (lung sliding and lung pulse sign), oxygenation status and peak airway pressure, in group U. Surgeon satisfaction score was also compared in both the groups. The accuracy of predicted DLT size between Group C and Group U was statistically significant (p=0.044). In Group C, 56% of patients showed a mismatch between the predicted DLT size and the actual size required, while in Group U, the mismatch was only 32.4%. The accuracy of DLT placement through group C was 41% as compared to 79% in Group U. Surgeon satisfaction score was also significantly higher in Group U as compared to Group C (p=0.0028). Thus, our study suggests that tracheal and chest ultrasonography for DLT size selection and placement for lung isolation is superior to clinical methods.

Preoperative lung ultrasound for confirming the double-lumen endotracheal tube position for one-lung ventilation: A systematic review and meta-analysis

Objectives

Insertion of a double-lumen endotracheal tube (DLT) is the most commonly used method for one-lung ventilation (OLV). This meta-analysis was aimed at investigating the performance of lung ultrasound in assessing the DLT position in OLV.

Methods

Electronic databases were searched for related trials from inception to October 2022. The primary outcome was the performance of ultrasound or clinical evaluation in confirming the correctness of the DLT position, using fiberoptic bronchoscopy or intraoperative direct visualization of lung collapse as the gold standard. The secondary outcome was the time required to confirm or adjust the DTL position.

Results

Five randomized controlled trials and three observational studies involving 771 patients were included in the meta-analysis. The pooled sensitivity and specificity of ultrasound were 0.93 (95% confidence interval [CI]: 0.79-0.98) and 0.61 (95% CI: 0.41-0.77), respectively, while those of clinical evaluation were 0.93 (95% CI: 0.73-0.99) and 0.35 (95% CI: 0.25-0.47), respectively. The pooled procedure duration was 122.27 s (95% CI: 20.85-223.69) with ultrasound and 112.03 s (95% CI: 95.30-128.76) with clinical evaluation. The area under the curve for discriminating the DLT position was 0.86 (95% CI: 0.82-0.88) for ultrasound and 0.52 (95% CI: 0.48-0.57) for clinical evaluation.

Conclusions

Compared to clinical evaluation, ultrasound has a similar sensitivity but a better specificity for confirming the correctness of the DLT position. Ultrasound is an acceptable imaging tool for assessing DTL placement in OLV.

Role of Lung Ultrasound in Confirmation of Double Lumen Endotracheal Tube Placement for Thoracic Surgeries: A Prospective Diagnostic Accuracy Study

Background

In thoracic surgeries requiring thoracotomy incisions, correct positioning of the double-lumen endotracheal tube (DLT) is mandatory. After the pandemic of novel COVID-19, using simple, noninvasive technology such as lung ultrasound (LUS) can be important in avoiding the possibility of spreading infectious diseases or contagious infections that can follow using fiberoptic bronchoscopy (FOB).

Objectives

We aimed to assess the accuracy of auscultation and LUS in relation to FOB in the assessment of DLT placement and to identify the possibility of using LUS as an alternative to FOB during DLT insertion.

Methods

This diagnostic accuracy study was conducted according to STARD guidelines; enrolled 120 cases requiring DLT intubation. After DLT insertion, all patients were examined by stethoscope, then by LUS for determination of DLT position, and then confirmed by FOB in the same patient.

Results

Three patients dropped out due to failed intubation, and only 117 cases were analyzed. Time was significantly longer for LUS than for auscultation and FOB and was insignificantly different between auscultation and FOB. Auscultation had 76.14% sensitivity, 34.48% specificity, and 65.81% accuracy in the determination of correct DLT placement. LUS had 92.05% sensitivity, 79.31% specificity, and 88.89% accuracy in detecting correct DLT placement. There was substantial agreement between LUS and FOB (κ = 0.705) and poor agreement between auscultation and FOB (κ = 0.104).

Conclusions

LUS can be used as a simple, noninvasive tool for detecting DLT placement with a substantial agreement with FOB.

Lung ultrasound is non-inferior to bronchoscopy for confirmation of double-lumen endotracheal tube positioning: a randomized controlled noninferiority study

BACKGROUND

Appropriate placement of left-sided double-lumen endotracheal tubes (LDLTs) is paramount for optimal visualization of the operative field during thoracic surgeries that require single lung ventilation. Appropriate placement of LDLTs is therefore confirmed with fiberoptic bronchoscopy (FOB) rather than clinical assessment alone. Recent studies have demonstrated lung ultrasound (US) is superior to clinical assessment alone for confirming placement of LDLT, but no large trials have compared US to the gold standard of FOB. This noninferiority trial was devised to compare lung US with FOB for LDLT positioning and achievement of lung collapse for operative exposure.

METHODS

This randomized, controlled, double-blind, noninferiority trial was conducted at the Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand from October 2017 to July 2019. The study enrolled 200 ASA classification 1-3 patients that were scheduled for elective thoracic surgery requiring placement of LDLT. Study patients were randomized into either the FOB group or the lung US group after initial blind placement of LDLT. Five patients were excluded due to protocol deviation. In the FOB group (n = 98), fiberoptic bronchoscopy was used to confirm lung collapse due to proper positioning of the LDLT, and to adjust the tube if necessary. In the US group (n = 97), lung ultrasonography of four pre-specified zones (upper and lower posterior and mid-axillary) was used to assess lung collapse and guide adjustment of the tube if necessary. The primary outcome was presence of adequate lung collapse as determined by visual grading by the attending surgeon on scale from 1 to 4. Secondary outcomes included the time needed to adjust and confirm lung collapse, the time from finishing LDLT positioning to the grading of lung collapse, and intraoperative parameters such has hypotension or hypertension, hypoxia, and hypercarbia. The patient, attending anesthesiologist, and attending thoracic surgeon were all blinded to the intervention arm.

RESULTS

The primary outcome of lung collapse by visual grading was similar between the intervention and the control groups, with 89 patients (91.8%) in the US group compared to 83 patients (84.1%) in the FOB group (p = 0.18) experiencing adequate collapse. This met criteria for noninferiority per protocol analysis. The median time needed to confirm and adjust LDLT position in the US group was 3 min (IQR 2-5), which was significantly shorter than the median time needed to perform the task in the FOB group (6 min, IQR 4-10) (p = 0.002).

CONCLUSIONS

In selected patients undergoing thoracic surgery requiring LDLT, lung ultrasonography was noninferior to fiberoptic bronchoscopy in achieving adequate lung collapse and reaches the desired outcome in less time.

TRIAL REGISTRATION

This study was registered at clinicaltrials.gov, NCT03314519 , Principal investigator: Kasana Raksamani, Date of registration: 19/10/2017.

Lung Ultrasound for Detecting Tracheal and Mainstem Intubation: A Systematic Review and Meta-Analysis

Precise positioning of the left or right main bronchus is a prerequisite for effective lung isolation in thoracic surgeries. This study aimed to clarify the ability of lung ultrasound to detect tracheal and mainstem intubation. Studies that investigated the ability of lung ultrasound to detect tracheal and mainstem intubation were searched from PubMed and ScienceDirect databases from their inception to March 2021. The pooled accuracy of this method and its sensitivity and specificity were computed with a fixed-effects model using Stata 14.0. Nine eligible articles that involved a total of 617 participants were included in this systematic review and meta-analysis. Overall, the accuracy of lung ultrasound in detecting tracheal and mainstem intubation was 86.7%, with a sensitivity of 93.0% and a specificity of 75.0%. Subgroup analysis revealed that the accuracy remained high regardless of patient age, ultrasonic method, sample size, study design or ultrasonic skills training. Sensitivity analysis indicated that the results were stable. Deeks' test showed no publication bias. These findings imply that lung ultrasound is an effective method for detecting tracheal and mainstem intubation.

Ultrasonography for airway management

Ultrasonography (USG) allows a new approach to the airway in anaesthesia and intensive care. USG visualises the airway from the mouth to the lungs. By exploring the entire airway, USG proposes new criteria (1) to assess the risk of difficult laryngoscopy, (2) to anticipate the management of a difficult airway, (3) to confirm the position of the endotracheal tube (ETT), and (4) to confirm that the lungs are effectively ventilated. Intraoperatively, USG may also help to resolve acute ventilatory problems such as pneumothorax, delayed selective bronchial intubation after patient positioning (Trendelenburg, prone or lateral position) or acute pulmonary oedema.

Unmasking the Lung Pulse for Detection of Endobronchial Intubation

The ultrasound lung pulse for detecting endobronchial intubation was first described in 2003 in the only study to date assessing its accuracy. It refers to rhythmic movement of the visceral pleura along the stationary parietal pleura as cardiac vibrations transmit through a motionless, airless lung. Compared to delayed visualization on chest radiography, this artifact immediately detects physiologic atelectasis. There is a scarcity of studies assessing the lung pulse, while several others that encountered this artifact did not even identify it. The lung pulse is useful for immediate detection of endobronchial intubation, but it remains unrecognized and underused by physicians.

Lung sonography can improve the specificity of determination of left-sided double-lumen tracheal tube position in both novices and experts: a randomised prospective study

Objective

Lung sonography can be helpful to determine the position of a left-sided double-lumen tube (DLT). However, clinical experience is required for correct assessment. We investigated whether lung sonography can improve the diagnostic efficacy of determining the DLT position in novices and experts.

Methods

In this randomised prospective clinical study, 88 patients were allocated to two groups using auscultation or lung sonography for initial assessment of the DLT position. In each group, two repeated assessments were performed; the first was performed by a novice, and the second was performed by an expert. The final DLT position was confirmed by fibre-optic bronchoscopy. The primary outcome was the diagnostic efficacy (including overall accuracy, sensitivity, and specificity) in confirming the DLT position.

Results

In both the novices and experts, the specificity of determining the DLT position was significantly higher with lung sonography than auscultation (60.0% vs. 21.7% and 66.7% vs. 37.5%, respectively). Additionally, the predictability of an incorrect position was similar between the novices and experts using lung sonography (area under the curve of 0.665 and 0.690, respectively).

Conclusions

Lung sonography can improve the diagnostic efficacy of detecting an incorrect DLT position in both novices and experts.

Intraoperative Anesthetic Management of the Thoracic Patient

The intraoperative anesthetic management for thoracic surgery can impact a patient's postoperative course, especially in patients with significant lung disease. One-lung ventilation poses an inherent risk to patients, including hypoxemia, acute lung injury, and right ventricular dysfunction. Patient-specific ventilator management strategies during one-lung ventilation can reduce postoperative morbidity.

Tracheal Ultrasound for the Accurate Confirmation of the Endotracheal Tube Position in Obese Patients

OBJECTIVES

Obesity is a serious disorder that may lead to numerous difficulties in endotracheal tube (ETT) management. This study investigated the potential of tracheal ultrasound (TUS) for the accurate confirmation of the ETT position in obese patients.

METHODS

A total of 68 obese patients undergoing tracheal intubation were enrolled in this study from January 2017 to June 2018. All patients received auscultation and TUS to evaluate the ETT position, which was ultimately verified by bronchoscopy. A correct position of the ETT was defined as placement at the trachea, whereas placement at the right/left main bronchus was classified as an incorrect position.

RESULTS

We found 58 correct placements of the ETT at the trachea, 8 incorrect placements at the right main bronchus, and 2 incorrect placements at the left main bronchus. Compared with auscultation, TUS showed higher accuracy (85.29% versus 67.65%; P = .005), sensitivity (84.48% versus 67.24%; P = .005), and specificity (90.00% versus 70.00%; P < .001), as well as lower rates of false-positive (10.00% versus 30.00%; P < .001) and false-negative (15.52% versus 32.76%; P = .005) results for detecting the correct placement of the ETT, defined as placement at the trachea.

CONCLUSIONS

Tracheal ultrasound is highly sensitive and specific in confirming the ETT position in obese patients.

Getting to know a familiar face: Current and emerging focused ultrasound applications for the perioperative setting

Ultrasound technology is available in many pediatric perioperative settings. There is an increasing number of ultrasound applications for anesthesiologists which may enhance clinical performance, procedural safety, and patient outcomes. This review highlights the literature and experience supporting focused ultrasound applications in the pediatric perioperative setting across varied disciplines including anesthesiology. The review also suggests strategies for building educational and infrastructural systems to translate this technology into clinical practice.

A prospective randomized controlled double-blind study comparing auscultation and lung ultrasonography in the assessment of double lumen tube position in elective thoracic surgeries involving one lung ventilation at a tertiary care cancer institute

Background

As lung ultrasound (LUS) can be used to identify regional lung ventilation and collapse, we hypothesize that LUS can be better than auscultation in assessing lung isolation and determining double lumen tube (DLT) position.

Methods

A randomized controlled study was conducted in tertiary care cancer institute from November 2014 to December 2015, including 100 adult patients undergoing elective thoracic surgeries. Patients with tracheostomy, difficult airway and pleural-based pathologies were excluded. After anesthesia induction and DLT insertion, patients were randomized into group A (auscultation) and group B (LUS). Regional ventilation was assessed by experienced anesthesiologists using the respective method for each group. Final confirmation of DLT position with a bronchoscope was performed by a blinded anesthesiologist. Contingency tables were plotted to determine sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for each method.

Results

Data from 91 patients were analyzed (group A = 47, group B = 44). Compared with auscultation, LUS had significantly higher sensitivity (94.1% vs. 73.3%, P = 0.010), PPV (57.1% vs. 35.5%, P = 0.044), NPV (93.8% vs. 75.0%, P = 0.018), accuracy (70.5% vs. 48.9%, P = 0.036) and required longer median time (161.5 vs. 114 s, P < 0.001) for assessment of DLT position. Differences in specificity (55.6% vs. 37.5%, P = 0.101) and area under curve (0.748; 95% CI: 0.604–0.893 vs. 0.554, 95% CI: 0.379–0.730; P = 0.109) were not significant.

Conclusions

Compared to auscultation, LUS is a superior method for assessing lung isolation and determining DLT position.

Point-of-care ultrasound versus auscultation in determining the position of double-lumen tube

This study was designed to assess the accuracy of point-of-care ultrasound in determining the position of double-lumen tubes (DLTs).A total of 103 patients who required DLT intubation were enrolled into the study. After DLTs were tracheal intubated in the supine position, an auscultation researcher and ultrasound researcher were sequentially invited in the operating room to conduct their evaluation of the DLT. After the end of their evaluation, fiberscope researchers (FRs) were invited in the operating room to evaluate the position of DLT using a fiberscope. After the patients were changed to the lateral position, the same evaluation process was repeated. These 3 researchers were blind to each other when they made their conclusions. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were obtained by statistical analysis.When left DLTs (LDLTs) were used, the accuracy of ultrasound (84.2% [72.1%, 92.5%]) was higher than the accuracy of auscultation (59.7% [45.8%, 72.4%]) (P < .01). When right DLTs (RDLTs) were used, the accuracy of ultrasound (89.1% [76.4%, 96.4%]) was higher than the accuracy of auscultation (67.4% [52.0%, 80.5%]) (P < .01). When LDLTs were used in the lateral position, the accuracy of ultrasound (75.4% [62.2%, 85.9%]) was higher than the accuracy of auscultation (54.4% [40.7%, 67.6%]) (P < .05). When RDLT were used, the accuracy of ultrasound (73.9% [58.9%, 85.7%]) was higher than the accuracy of auscultation (47.8% [32.9%, 63.1%]) (P < .05).Assessment via point-of-care ultrasound is superior to auscultation in determining the position of DLTs.

Point-of-care ultrasound (POCUS) of the upper airway

Airway management is a critical skill in the practice of several medical specialities including anesthesia, emergency medicine, and critical care. Over the years mounting evidence has showed an increasing role of ultrasound (US) in airway management. The objective of this narrative review is to provide an overview of the indications for point-of-care ultrasound (POCUS) of the upper airway. The use of US to guide and assist clinical airway management has potential benefits for both provider and patient. Ultrasound can be utilized to determine airway size and predict the appropriate diameter of single-lumen endotracheal tubes (ETTs), double-lumen ETTs, and tracheostomy tubes. Ultrasonography can differentiate tracheal, esophageal, and endobronchial intubation. Ultrasonography of the neck can accurately localize the cricothyroid membrane for emergency airway access and similarly identify tracheal rings for US-guided tracheostomy. In addition, US can identify vocal cord dysfunction and pathology before induction of anesthesia. A rapidly growing body of evidence showing ultrasonography used in conjunction with hands-on management of the airway may benefit patient care. Increasing awareness and use of POCUS for many indications have resulted in technologic advancements and increased accessibility and portability. Upper airway POCUS has the potential to become the first-line non-invasive adjunct assessment tool in airway management.

A prospective comparative study to evaluate the utility of lung ultrasonography to improve the accuracy of traditional clinical methods to confirm position of left sided double lumen tube in elective thoracic surgeries

Background and Aims:

Traditional clinical methods like auscultation or inspection have been found to be inaccurate in confirmation of double-lumen tube (DLT) position. Lung ultrasonography (USG) reliably identifies the tidal movement (lung sliding) and the collapse of the lung (lung pulse). We intended to check whether the accuracy of clinical methods can be improved by the addition of USG in confirmation of left DLT (LDLT) position.

Methods:

A single centred, prospective, comparative study was conducted involving 70 patients undergoing thoracic surgeries requiring the use of LDLT. The patients were assigned to Group A - where LDLT position was assessed by using clinical methods alone, and Group B - where LDLT position was assessed by USG and clinical methods. The correct position was predicted when USG demonstrated the absence of lung sliding and the presence of lung pulse on the operative side, the presence of lung sliding on non-operative side, along with normal airway pressures and oxygenation. The final verification of LDLT position was done by direct observation of lung isolation by one surgeon who was blinded to the method of confirmation. Contingency tables were drawn to calculate sensitivity, specificity, positive predictive value, negative predictive value and accuracy of each method.

Results:

Compared to clinical methods alone, addition of lung USG improved sensitivity (75% vs. 88%), specificity (18% vs. 75%) and accuracy (57% vs. 85%) for correct prediction of LDLT position.

Conclusion:

USG is a useful addition to the armamentarium of anaesthesiologist for the confirmation of LDLT position.

The use of lung ultrasonography to confirm lung isolation in an infant who underwent emergent video-assisted thoracoscopic surgery: a case report

Video-assisted thoracoscopic surgery for pediatric patients has gained popularity due to better outcomes than open surgery. For this procedure, one-lung ventilation may be necessary to provide an adequate surgical field. Confirming lung isolation is crucial when one-lung ventilation is required. Recently, we experienced a case in which one-lung ventilation was confirmed by ultrasonography using the lung sliding sign and the lung pulse in an infant. Since lung ultrasonography can be performed easily and quickly, it may be a useful method to confirm lung isolation, particularly in emergency surgeries with limited time, devices, and experienced anesthesiologists.

Comparison between transthoracic lung ultrasound and a clinical method in confirming the position of double-lumen tube in thoracic anaesthesia. A pilot study

OBJECTIVE

To compare the ability of lung ultrasound and a clinical method in the confirmation of a selective bronchial intubation by left double-lumen tube in elective thoracic surgery.

MATERIAL AND METHODS

A prospective and blind, observational study was conducted in the setting of a university hospital operating room assigned for thoracic surgery. A single group of 105 consecutive patients from a total of 130, were included. After blind intubation, the position of the tube was confirmed by clinical and ultrasound assessment. Finally, the fiberoptic bronchoscopy confirmation as a reference standard was used to confirm the position of the tube. Under manual ventilation, by sequentially clamping the tracheal and bronchial limbs of the tube, clinical confirmation was made by auscultation, capnography, visualizing the chest wall expansion, and perceiving the lung compliance in the reservoir bag. Ultrasound confirmation was obtained by visualizing lung sliding, diaphragmatic movements, and the appearance of lung pulse sign.

RESULTS

The sensitivity of the clinical method was 84.5%, with a specificity of 41.1%. The positive and negative likelihood ratio was 1.44 and 0.38, respectively. The sensitivity of the ultrasound method was 98.6%, specificity was 52.9%, with a positive likelihood ratio of 2.10 and a negative likelihood ratio of 0.03. Comparisons between the diagnostic performance of the 2 methods were calculated with McNemar's test. There was a significant difference in sensitivity between the ultrasound method and the clinical method (P=.002). Nevertheless, there was no statistically significant difference in specificity between both methods (P=.34). A p value<.01 was considered statistically significant.

CONCLUSION

Lung ultrasound was superior to the clinical method in confirming the adequate position of the left double-lumen tube. On the other hand, in confirming the misplacement of the tube, differences between both methods could not be ensured.

Ultrasonography for confirmation of endotracheal tube placement: a systematic review and meta-analysis

OBJECTIVE

This study aimed to undertake a systematic review and meta-analysis to summarize evidence on the diagnostic value of ultrasonography for the assessment of endotracheal tube placement in adult patients.

METHODS

The major databases, PubMed, EMBASE, and the Cochrane Library, were searched for studies published from inception to June 2014. We selected studies that used ultrasonography to confirm endotracheal tube placement. The search was limited to human studies, and had no publication date or country restrictions. Exclusion criteria included case reports, comments, reviews, guidelines and animal studies. Two reviewers extracted and verified the data independently. We summarized test performance characteristics with the use of forest plots, hierarchical summary receiver operating characteristic (HSROC) curves, and bivariate random effect models. Meta-regression analysis was performed to explore the source of heterogeneity. The methodological quality of individual studies was evaluated using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool.

RESULTS

A total of 12 eligible studies involving adult patients and cadaveric models were identified from 1488 references. For detection of esophageal intubation, the pooled sensitivity was 0.93 (95% CI: 0.86-0.96) and the specificity was 0.97 (95% CI: 0.95-0.98). The area under the summary ROC curve was 0.97 (95% CI: 0.95-0.98). The positive and negative likelihood ratios were 26.98 (95% CI: 19.32-37.66) and 0.08 (95% CI: 0.04-0.15), respectively.

CONCLUSIONS

Current evidence supports that ultrasonography has high diagnostic value for identifying esophageal intubation. With optimal sensitivity and specificity, ultrasonography can be a valuable adjunct in this aspect of airway assessment, especially in situations where capnography may be unreliable.

Ultrasonography for clinical decision-making and intervention in airway management: from the mouth to the lungs and pleurae

OBJECTIVES

To create a state-of-the-art overview of the new and expanding role of ultrasonography in clinical decision-making, intervention and management of the upper and lower airways, that is clinically relevant, up-to-date and practically useful for clinicians.

METHODS

This is a narrative review combined with a structured Medline literature search.

RESULTS

Ultrasonography can be utilised to predict airway difficulty during induction of anaesthesia, evaluate if the stomach is empty or possesses gastric content that poses an aspiration risk, localise the essential cricothyroid membrane prior to difficult airway management, perform nerve blocks for awake intubation, confirm tracheal or oesophageal intubation and facilitate localisation of tracheal rings for tracheostomy. Ultrasonography is an excellent diagnostic tool in intraoperative and emergency diagnosis of pneumothorax. It also enables diagnosis and treatment of interstitial syndrome, lung consolidation, atelectasis, pleural effusion and differentiates causes of acute breathlessness during pregnancy. Patient safety can be enhanced by performing procedures under ultrasound guidance, e.g. thoracocentesis, vascular line access and help guide timing of removal of chest tubes by quantification of residual pneumothorax size.

CONCLUSIONS

Ultrasonography used in conjunction with hands-on management of the upper and lower airways has multiple advantages. There is a rapidly growing body of evidence showing its benefits.

TEACHING POINTS

• Ultrasonography is becoming essential in management of the upper and lower airways. • The tracheal structures can be identified by ultrasonography, even when unidentifiable by palpation. • Ultrasonography is the primary diagnostic approach in suspicion of intraoperative pneumothorax. • Point-of-care ultrasonography of the airways has a steep learning curve. • Lung ultrasonography allows treatment of interstitial syndrome, consolidation, atelectasis and effusion.

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.

Verification of endotracheal intubation in obese patients - temporal comparison of ultrasound vs. auscultation and capnography

BACKGROUND

Ultrasound (US) may have an emerging role as an adjunct in verification of endotracheal intubation. Obtaining optimal US images in obese patients is generally regarded more difficult than for other patients. This study compared the time consumption of bilateral lung US with auscultation and capnography for verifying endotracheal intubation in obese patients.

METHODS

A prospective, paired and investigator-blinded study performed in the operating theatre. Twenty-four adult patients requiring endotracheal intubation for bariatric surgery were included. During post-intubation bag ventilation, bilateral lung US was performed for detection of lungsliding indicating lung ventilation simultaneous with capnography and auscultation of epigastrium and chest. Primary outcome measure was the time difference to confirmed endotracheal intubation between US and auscultation alone. The secondary outcome measure was time difference between US and auscultation combined with capnography.

RESULTS

Both methods verified endotracheal tube placement in all patients. No significant difference was found between US compared with auscultation alone. Median time for verification by auscultation alone was 47.5 s [interquartile (IQR) 40-51 s], with a mean difference of -0.3 s in favor of US (95% confidence interval -3.5-2.9 s) P = 0.87. Comparing US with the combination of auscultation and capnography, there was a significant difference between the two methods. Median time for verification by US was 43 s (IQR 40-51 s) vs. 55 s (IQR 46-65 s), P < 0.0001.

CONCLUSION

In obese patients, verification of endotracheal tube placement with US is as fast as auscultation alone and faster than the standard method of auscultation and capnography.

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.