Methods of lung separation

Research and development of the sOLVe Tube™ dual lumen endobronchial tube: from concept to construct

Introduction

Dual lumen endobronchial tubes (DLTs) are frequently used for lung isolation and one lung ventilation in thoracic surgery and other specialized clinical scenarios. Modern DLTs are large and rigid, and account for half of all tracheobronchial injuries. Their 70 year old design has numerous flaws which limit their safety and clinical utility. Our research team set out to design a new and improved DLT to mitigate these shortcomings, and then test the proposed device to ensure proper function.

Methods

Using published airway anatomy data and computed tomography imaging from 195 thoracic surgery patients, we designed a new DLT with a single size/configuration that would fit into adult surgery patients. This single "Universal design" was intended to replace both left and right sided 35Fr-41Fr DLTs (8 total products), while remaining small in diameter (35Fr). Other design goals included: 1) making intubation easier and safer, 2) allowing full sized therapeutic bronchoscopes to fit into this tube, 3) making the DLT more resistant to dislodgement. After design process completion the proposed dimensions were tested against 195 patients' left and right mainstem bronchi for radiographic fit. Once production prototypes were manufactured, they were tested in large adult Yorkshire pigs and fresh human cadavers for anatomic fit and performance.

Results

The proposed design passed the radiographic fit test in all 195 patients for both left and right mainstem endobronchial placement. Intubation was successful and deemed atraumatic in all pigs and cadavers, and the device appropriately fit in both the right and left mainstem bronchi. Lung isolation was successfully achieved and the device proved resistant to axial force dislodgement.

Conclusion

We propose a new design for a novel DLT meant to replace 8 currently supplied adult configurations with a single, one size/configuration fits all product that allows for large bore bronchoscopy and resists axial force dislodgement.

[Current approaches to anesthetic management in thoracic surgery-An evaluation from the German Thoracic Registry]

BACKGROUND

While many hospitals in Germany perform thoracic surgery, anesthetic techniques and methods that are actually used are usually only known for individual departments. This study describes the general anesthetic management of three typical thoracic surgical procedures across multiple institutions.

MATERIAL AND METHODS

The German Thoracic Registry recorded 4614 patients in 5 institutions between 2016 and 2019. Hospitals with a minimum number of more than 50 thoracic procedures per year are eligible for inclusion in the registry. To analyze the anesthetic management, a matching process yielded three comparable patient groups (n = 1506) that differed solely in the surgical procedure. Three surgical procedures with varying degrees of invasiveness were selected: Group A = video-assisted thoracoscopic surgery (VATS) with wedge resection, group B = VATS with lobectomy, group C = open thoracotomy. Statistical analysis was performed descriptively using relative and absolute frequencies. Dichotomous variables were compared using the χ²-test.

RESULTS

The study enrolled patients with a median age of 65.6 years. The mean value of the American Society of Anesthesiologists (ASA) classification was 2.8. One lung ventilation was most commonly performed (group A = 98.2%, group B = 99.4%, group C = 98.0%) with double lumen tubes (DLT). Bronchial blockers (group A = 0.2%, group B = 0.4%, group C = 0%) were rarely used. Primary bronchoscopy was used to control double lumen tubes after insertion in the majority of cases (group A = 77.5%, group B = 73.1%, group C= 79.7%). Continuous positive airway pressure (CPAP, group A = 1.2%, group B = 1.4%, group C = 5.1%) and jet ventilation (group A = 1.6%, group B = 1.6%, group C = 1.4%) were rarely used intraoperatively. In group C, the administration of a vasopressor was also more frequently required (group A = 59.9%, group B = 77.8%, group C = 86%). A central venous catheter was established in 30.1% of all patients in group A, 39.8% in group B and 73.3% in group C. Patients in group A received an arterial catheter less frequently (71.7%) when compared to groups B (96.4%) and C (95.2%). Total intravenous anesthesia with propofol was used in most patients (group A = 67.7%, group B 61.6%, group C 75.7%). Propofol supplemented by volatile anesthetics was used less frequently (group A = 28.5%, group B = 35.5%, group C = 23.7%). With increasing invasiveness of the surgical procedure, placement of an epidural catheter was preferred (group A = 18.9%, group B = 29.5%, group C = 64.1%). Paravertebral catheters (group A = 7.6%, group B = 4.4%, group C = 4.8%) or a single infiltration of the paravertebral space were performed less frequently (group A = 7.8%, group B = 17.7%, group C = 11.6%). Postoperatively, some patients (3.4-25.7%) were transferred to the general ward. The largest proportion of patients transferred to a general ward underwent less invasive thoracic procedures (group A). When the extent of resection was greater (group B and group C) patients were mostly transferred to an intermediate care unit (IMC) or an intensive care unit (ICU). The insertion of invasive catheters was neither associated with the patients' ASA classification nor preoperative pathologic pulmonary function.

CONCLUSION

Our data indicate that less invasive thoracic operations are associated with a reduction of invasive anesthetic procedures. As the presented data are descriptive, further studies are required to determine the impact of invasive anesthetic procedures on patient-related outcomes. This evaluation of the anesthetic management in experienced thoracic anesthesiology departments represents the next step towards establishing national quality standards and promoting structural quality in thoracic anesthesia.

Videolaryngoscopy versus direct laryngoscopy for double-lumen endotracheal tube intubation in thoracic surgery - a randomised controlled clinical trial

Background

Double-lumen tube (DLT) intubation is necessary for thoracic surgery and other operations with the need for lung separation. However, DLT insertion is complex and might result in airway trauma. A new videolaryngoscopy (GVL) with a thin blade might improve the intubation time and reduce complexity as well as iatrogenic airway complications compared to conventional direct laryngoscopy (DL) for DLT intubation.

Methods

A randomised, controlled trial was conducted in 70 patients undergoing elective thoracic surgery using DLT for lung separation. Primary endpoint was time to successful intubation. The secondary endpoints of this study were number of intubation attempts, the assessment of difficulty, any complications during DLT intubation and the incidence of objective trauma of the oropharynx and supraglottic space and intubation-related subjective symptoms.

Results

65 patients were included (DL group [n  =  31], GVL group [n  =  34]). Median intubation time (25th–75th percentiles) in GVL group was 93 s (63–160) versus 74 (58–94) in DL group [p = 0.044]. GVL resulted in significantly improved visualisation of the larynx (Cormack and Lehane grade of 1 in GVL group was 97% vs. 74% in DL Group [p = 0.008]). Endoscopic examinations revealed significant differences in GVL group compared to DL group showing less red-blooded vocal cord [p = 0.004], vocal cord haematoma [p = 0.022] and vocal cord haemorrhage [p = 0.002]. No significant differences regarding the postoperative subjective symptoms of airway were found.

Conclusions

Videolaryngoscopy using the GlideScope®-Titanium shortly prolongs DLT intubation duration compared to direct laryngoscopy but improves the view. Objective intubation trauma but not subjective complaints are reduced.

Trial registration

German Clinical Trial Register DRKS00020978, retrospectively registered on 09. March 2020.

Effects of bronchial blockers on one-lung ventilation in general anesthesia: A randomized controlled trail

BACKGROUND

Double-lumen bronchial tubes (DLBT) and bronchial blockers (BB) are commonly used in the anesthesia for clinical thoracic surgery. But there are few systematic clinical comparisons between them. In this study, the effects of BB and DLBT on one-lung ventilation (OLV) are studied.

METHODS

The 200 patients with thoracic tuberculosis undergoing thoracic surgery, were randomly assigned to group A (DLBT) and group B (BB). Intubation time, hemodynamic changes (mean arterial pressure [MAP], heart rate [HR]), and arterial blood gas indicators (arterial partial pressure of carbon dioxide [PaCO2], arterial partial pressure of oxygen [PaO2], airway plateau pressure [Pplat], and airway peak pressure [Ppeak]) at 4 time points were recorded. Complications such as hoarseness, pulmonary infection, pharyngalgia, and surgical success rate were also evaluated postoperatively.

RESULTS

Intubation times were shorter in group B. Both MAP and HR in group A were significantly higher 1 minute after intubation than before, but also higher than those in group B. PaO2 levels were lower in both groups during (OLV) than immediately after anesthesia and after two-lung ventilation (TLV), with PaO2 being lower after 60 minutes of OLV than after 20 minutes of OLV. Furthermore, at both points during OLV, PaO2 was lower in group A than in group B. No significant differences in PaCO2 were found between the 2 groups. Ppeak and Pplat were increased in both groups during OLV, with both being higher in group A than in group B. The incidence of postoperative hoarseness, pulmonary infection, and pharyngalgia were lower in group B. There was no significant difference in the success rate of operation between the 2 groups.

CONCLUSIONS

Compare with using DLBT, implementation of BB in general anesthesia has less impact on hemodynamics, PaO2 and airway pressures, and achieves lower incidence of postoperative complication.

Right upper lobe anatomy revisited: a computed tomography scan study

BACKGROUND

The double lumen tube (DLT) has become the most popular way to isolate the lungs for thoracic surgery. The variable anatomy of the right main stem bronchus (RMSB) seems to be the main reason clinicians are unwilling to use the right-sided DLT (R-DLT). The factors that could compromise the adequate ventilation of the right lung are mostly the variable length of the RMSB and the misalignment of the lateral orifice of the R-DLT in regard to the right upper lobe bronchus (RULB). The objectives of this study were to validate an alternative method to estimate the RMSB length, and to determine the distribution of the angulation of the ostium of the RULB.

METHODS

From high-resolution computed tomography scans of the thorax of 106 consecutive patients, the length of the RMSB was measured using Kim's method and the carina-to-carina method. The angle between the RULB origin and the lateral aspect of the RMSB was also measured. All these measurements were correlated and inter-observer variation documented.

RESULTS

From the Kim's method, the mean (standard deviation [SD]) length of the RMSB was 25.5 (4.7) mm. From the alternative carina-to-carina method, the mean (SD) length of RMSB was 29.4 (4.6) mm. The inter-observer agreement was substantial with both methods (Kim's method: intraclass correlation coefficient [ICC] = 0.84; carina-to-carina method: ICC = 0.95). Both measures were closely related (ICC = 0.93; P < 0.001). The RULB presented a wide range angulation [mean (SD), 0.1 (9.5)°; range, -28.6 to 21.2].

CONCLUSION

These anatomic observations provide a better understanding of the variable anatomy of the right bronchial tree and may guide thoracic anesthesiologists in the choice of the best lung isolation device for their patients.

Comparison of McGRATH MAC and Macintosh laryngoscopes for double-lumen endotracheal tube intubation by anesthesia residents: a prospective randomized clinical trial

STUDY OBJECTIVE

This study aimed to compare the utility of McGRATH MAC (McG) and Macintosh (McL) laryngoscopes for double-lumen endotracheal tube intubation in patients undergoing elective surgery.

DESIGN

Randomized clinical trial.

SETTING

Operating room.

PATIENTS

Fifty adult patients scheduled for elective surgery under 1-lung ventilation with American Society of Anesthesiologists physical status 1 to 3.

INTERVENTIONS

Double-lumen endotracheal tube intubation was performed with the McG (McG group; 25 patients) or conventional McL (McL group; 25 patients) laryngoscope by anesthesia residents.

MEASUREMENTS

The number of attempts to successful intubation, intubation time, percentage of glottis opening score, and subjective difficulty of laryngoscopy and tube passage through the glottis were assessed.

MAIN RESULTS

The total numbers of intubation attempts were 1 (McG group, 24 patients; McL group, 16 patients), 2 (McG group, 1 patient; McL group, 8 patients), and 3 (McG group, 0 patient; McL group, 1 patient), with significant differences between the two groups (P = .018). Intubation time was significantly shorter in the McG group compared with the McL group (McG: 17.1 ± 4.6 seconds vs McL: 20.8 ± 5.9 seconds, P = .026). The percentage of glottis opening score was significantly higher in the McG group compared with the McL group (McG: 88.4% ± 13.7% vs McL: 71.4% ± 20.4%, P = .004).

CONCLUSIONS

The McG demonstrated a better intubation profile compared with the McL, possibly due to its ease of use for double-lumen endotracheal tube intubation. Clinical Trial registry number: UMIN000014636.

Tracheal laceration during intubation of a double-lumen tube and intraoperative fiberoptic bronchoscopic evaluation through an LMA in the lateral position -A case report-

A 76-year-old, 148-cm woman was scheduled for right upper lobectomy. A 32 Fr left-sided double lumen tube was placed using a conventional technique. Despite several attempts under fiberoptic bronchoscope-guidance, we could not locate the double lumen tube properly. We thus decided to proceed with the bronchial tube in the right mainstem bronchus. During surgery, 8-cm-long laceration was noted on the posterolateral side of the trachea. To check the possibility of laceration of the proximal trachea, the double lumen tube was changed to an LMA for use as a conduit for fiberoptic bronchoscopic evaluation in the lateral position. A plain endotracheal tube with the cuff modified and collapsed was re-intubated after evaluation. And then she was transferred to SICU.

[Placement of a bronchial blocker through the I-gel supraglottic airway device for single-lung ventilation: preliminary study]

To describe the use of the I-gel supraglottic airway device when placing a bronchial blocker for single-lung ventilation, as applied in a preliminary study to explore the feasibility of adopting the technique with appropriate, selected patients undergoing certain thoracic surgery procedures. We used the technique for single-lung ventilation in 25 patients who required isolation of a lung for a variety of thoracic surgical procedures. A bronchial blocker was placed under direct visualization through a fiberoptic bronchoscope and the I-gel supraglottic device. The I-gel mask allowed us to establish a reliable, safe seal of the airway. For an anesthetist with sufficient experience in managing a flexible fiberoptic bronchoscope, it was possible to carry out all procedures without remarkable anesthetic or surgical events. Single-lung ventilation achieved by introducing a bronchial blocker through the I-gel supraglottic device can facilitate safe, effective management of selected patients who must undergo certain thoracic surgery procedures.

Unilateral administration of a drug into the lung of a small animal

Background

The selective unilateral administration of drugs into a single lung of a rat is difficult because of the small airway diameter. Therefore, a simple method for unilateral administration into rat lung is needed.

Methods

Rats were assigned to 1 of 2 groups according to the direction of the catheter used for drug administration. Anesthetized rats were intubated, and curved epidural catheters were rotated up to a maximum of 90° toward the left lung (group L) or right lung (group R). Bronchial catheters were then inserted via a tracheal tube and fixed. Methylene blue (0.3 ml) was injected via the epidural catheter. Additionally, to compare survival rates, rats were assigned to one of two groups according to the drug administration route. In group T, bleomycin hydrochloride (20 mg/kg) in 0.3 ml of phosphate-buffered saline (PBS) was administrated into the lung intratracheally via a tracheal tube. In group B, the same dose of bleomycin was administrated into the lung intrabronchially via a bronchial catheter, targeting the left lung.

Results

Gross examination revealed that targeted administration was 100% successful. Methylene blue was observed in the right lung of all rats in the R group and in the left lung of all rats in the L group. The survival rate was higher in group B than in group T.

Conclusions

The intrabronchial method offers an advantage over tracheal administration as it decreases mortality and allows the administration of a drug unilaterally into a single lung or into a localized area without the need for double-lumen tubes or more invasive procedures.

Can ultrasound be useful for predicting the size of a left double-lumen bronchial tube? Tracheal width as measured by ultrasonography versus computed tomography

STUDY OBJECTIVE

To correlate tracheal width as measured by ultrasound with width measured by computed tomography (CT), and to evaluate the possible role of ultrasound in the selection of the proper size of left-sided double-lumen endotracheal tubes (LDLTs).

DESIGN

Two independent, prospective, observational clinical studies (Study 1 and Study 2).

SETTING

University hospital.

PATIENTS

Study 1 included 25 patients and Study 2 included 20 adult thoracic surgery patients who required a LDLT during anesthesia.

INTERVENTIONS AND MEASUREMENTS

In Study 1, CT measurements of tracheal width were made at the coronary plane 0.5 cm above the sternoclavicular joint; CT measurements of the left main bronchus diameter were made 1 cm below the carina. Ultrasound measurement of tracheal width was performed just above the sternoclavicular joint in the transversal section. In Study 2, patients' tracheas were intubated with a LDLT based on ultrasound measurements. The frequencies of incorrect selections of LDLT and unsatisfactory lung collapse were analyzed.

MAIN RESULTS

There was a strong correlation between tracheal width as measured by ultrasound and tracheal width (r=0.882, P<0.001) and left main bronchus width (r=0.832, P<0.001) as measured by CT. In 5 cases (25%), the incorrect LDLT by ultrasound was selected; and one (5%) was found to have an unsatisfactory lung collapse.

CONCLUSION

Measurement of the outer tracheal width by ultrasound can be a useful method for predicting the diameter of left main bronchus and for selecting a LDLT.

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.

Cardiopulmonary changes induced during one-lung ventilation in anesthetized dogs with a closed thoracic cavity

OBJECTIVE

To evaluate the effects of one-lung ventilation (OLV) on oxygen delivery (DO2) in anesthetized dogs with a closed thoracic cavity.

ANIMALS

7 clinically normal adult Walker Hound dogs.

PROCEDURE

Dogs were anesthetized. Catheters were inserted in a dorsal pedal artery and the pulmonary artery. Dogs were positioned in right lateral recumbency. Data were collected at baseline (Paco2 of 35 to 45 mm Hg), during two-lung ventilation, and 15 minutes after creating OLV. Hemodynamic and respiratory variables were analyzed and calculations performed to obtain DO2, and values were compared among the various time points by use of an ANOVA for repeated measures.

RESULTS

OLV induced a significant augmentation of shunt fraction that resulted in a significant reduction in Pao2, arterial oxygen saturation, and arterial oxygen content. Cardiac index was not significantly changed. The net result was that DO2 was not significantly affected by OLV.

CONCLUSIONS AND CLINICAL RELEVANCE

Use of OLV in healthy dogs does not induce significant changes in DO2, which is the ultimate variable to use when evaluating tissue oxygenation. One-lung ventilation can be initiated safely in dogs before entering the thoracic cavity during surgery. Additional studies are necessary to evaluate OLV in clinically affected patients and variations in age, body position, and type of anesthetic protocol.

Single-lung ventilation with a cuffed endotracheal tube in a child with a left mainstem bronchus disruption

IMPLICATIONS

We report a case of management of ventilation during operative repair of a traumatic left mainstem bronchial disruption in a pediatric patient. With the use of a conventional cuffed endotracheal tube, with the cuff partially in the right mainstem bronchus and partially in the trachea, we successfully managed the case with single-lung ventilation.