Abstract

The main objective of this systematic review and meta-analysis was to determine the safety and effectiveness of VivaSight double-lumen tubes (VS-DLTs) in one-lung ventilation (OLV) compared to conventional DLTs (c-DLTs). The study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement’s guidelines. From the database’s inception to December 2022, we searched seven different databases. We included 364 patients from six randomized controlled trials who were scheduled to undergo surgery requiring OLV. The Cochrane risk of bias assessment tool was utilized to determine the risk of bias. The odds ratio (OR) was estimated for categorical variables, while the mean difference was calculated for continuous variables. Patients were randomly assigned to the VS-DLT or c-DLT group. The results revealed that patients in the c-DLT group have longer intubation time than the VS-DLT patients (mean difference [MD] = –90.01; 95% confidence interval [CI], –161.33 to –18.69; P = 0.01). Significantly, more secretions were present in the VS-DLT group than in the c-DLT group (OR = 4.24; CI, 1.96 to 9.13; P = 0.0002). Also, the fiberoptic bronchoscope was used more frequently in the c-DLT group compared to the VS-DLT group (OR = 0.01 [0.00, 0.07]; P < 0.00001). We found that VS-DLT was safe as the pooled analysis showed no significant difference according to side effects such as hoarseness and sore throat. The other outcomes, such as dislodgement, the clearance of secretions, and the quality of lung deflation (excellent), were non-significant between the two groups.

Keywords

conventional double-lumen tube, double-lumen tube, lung isolation, one-lung ventilation, VivaSight double-lumen tube

---

Introduction

While lung isolation techniques were initially designed for lung resection surgeries, they are now widely used for one-lung ventilation (OLV) in patients undergoing oesophagal, aorta, and thoracic spine procedures. OLV has expanded to other specialities as the frequency of minimally invasive laparoscopic-thoracoscopic procedures for upper gastrointestinal surgeries has increased. Therefore, anesthetists must be well-versed in the numerous techniques for establishing and preserving OLV.¹ There are three approaches used to achieve lung isolation and OLV: double-lumen tubes (DLTs), bronchial blockers, and single-lumen tubes, which are inserted into the right or left mainstem bronchus; however, DLTs are the gold standard.^1-3 According to studies conducted in the Middle East, the United Kingdom, and Italy, more than 90% of thoracic anesthesiologists favor DLTs.^3-5

DLT can anatomically or physiologically isolate the lung; it can switch ventilation from two to one lung (or vice versa) and correct intraoperative hypoxia.⁶ DLT has numerous advantages, including preventing healthy lung contamination, as in lung abscesses. DLT also aids in managing ventilation distribution, as in bronchopleural fistula, and can permit the lavage of a single lung, as in cystic fibrosis.¹ There are two ways to insert DLTs, blind insertion and fiberoptic bronchoscope (FOB)-assisted.^7,8 The blind technique is associated with a high rate of DLT misplacement, particularly among non-thoracic anesthesiologists (30%–78%).^8,9 After intubation and patient positioning, it is strongly recommended to use a FOB to verify the correct location of DLT. FOB is an invasive method used for diagnostic and therapeutic purposes for a long time.¹⁰ Per procedure, reusable FOB costs range from 89.43 USD to 312.20 USD.^11,12 As a result of the constant advancement of technology, the VivaSight DLT (VS-DLT) emerged.

The VS-DLT is designed similarly to the conventional DLT (c-DLT), with the addition of a camera and a light source,¹³ enabling continuous observation and monitoring of endotracheal tube placement. Consequently, VS-DLT diminishes the FOB’s function and eliminates its negative consequences.¹⁴ VS-DLT also has an integrated flushing system for intratracheal cleansing of blood and secretions.¹³ VS-DLT placement is three times quicker than DLT.13 The current cost of VS-DLT ranges between 225 and 300 dollars,^11,12 and there is a link between VS-DLT and cost reduction compared to c-DLT.¹²

As discussed in multiple randomized clinical trials (RCTs), VS-DLT has several advantages over c-DLT; the present meta-analysis is based on RCTs to compare the efficacy and safety of VS-DLT and c-DLT.

Methods

Eligibility Criteria

The included studies were RCTs of patients undergoing procedures requiring OLV that compared the VS-DLT and the c-DLT. The measured outcomes were intubation time (seconds), the use of FOB, sore throat, hoarseness of voice, dislodgement, dislodgement occurrence time during positioning, dislodgement occurrence time during surgery, dislodgement occurrence time during both positioning and surgery, the presence of secretions during the case, and the effectiveness of clearance of secretions and the quality of lung deflation (excellent). Studies that were in different languages rather than English, observational studies, abstracts, reviews, editorials, case reports, and case series were excluded.

Search

The authors searched the following databases PubMed, Scopus, Web of Science, Embase via Elsevier, MEDLINE via Ebsco, CINAHL via Ebsco, and The Cochrane Library for clinical trials in CENTRAL from inception until December 2022. We used the following search strategy; ((One Lung Ventilation) OR (Ventilation, One-Lung) OR (Single-Lung Ventilation) OR (Single Lung Ventilation) OR (Single-Lung Ventilations) OR (Ventilation, Single-Lung) OR (Ventilations, Single-Lung) OR (Lung Separation Techniques) OR (Lung Separation Technique) OR (Separation Technique, Lung) OR (Separation Techniques, Lung) OR (technique, Lung Separation) OR (Techniques, Lung Separation)) AND ((A double-lumen endotracheal tube) OR (double-lumen endobronchial tube) OR (Double-lumen tube) OR DLT) AND (VivaSight OR (VivaSight-DL)). Only articles in English were included. We also carefully inspected the reference lists of included papers.

Study Screen and Selection

Screening

Three authors independently screened the titles and abstracts against the inclusion criteria. Once the initial title/abstract screening was completed, the full texts of the included studies from that stage were reviewed to determine if they should be included. Disagreements were settled by consensus. The screening process is summarized in Figure 1.

A standardized form was used for data extraction of characteristics of studies, outcomes, and risk of bias. Three authors conducted data extraction. The following data for study characteristics and summary were extracted for each included study: baseline characteristics like age, sex, body mass index, American Society of Anesthesiologists physical status, and Cormack & Lehane grade. The summary table includes the study design, title, inclusion and exclusion criteria, measured outcomes, and the main findings.

Risk of Bias Assessment

Three authors independently assessed the risk of bias for each study using the Cochrane Risk of Bias tool.¹⁵ A rating of “high,” “low,” or “unclear” was assigned to the following domains: random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, inadequate outcome data, selective reporting, and other biases. Trials with a high risk of bias were considered to have a high risk for one or more of these key domains. Trials with a low risk of bias in each area were deemed to have a low risk of bias. Otherwise, they were deemed to have an unclear risk of bias.¹⁶

Data Analysis

The overall intervention effect was calculated using RevMan 5. We used the odds ratio (OR) for dichotomous outcomes and mean difference (MD) for continuous outcomes. We planned to do a meta-analysis using a random effects model if there were two or more studies with the same outcome. We did not contact investigators or study sponsors to provide missing data.

Assessing the Heterogeneity

The Chi-square test (also known as the Cochrane Q test), I-squared (I²), and X2 tests were used to evaluate the heterogeneity of the studies. A P-value of < 0.1 shows significant heterogeneity. High heterogeneity is indicated by I-square values ≥ 50%.

Reporting Publication Bias

We did not assess publication bias because the included studies were less than 10.

Results

Results of the Search

The database search yielded 96 studies. We did backward and forward citations, but no results were found. The total number of publications found was 96. After duplicates were removed, the unique number of articles was 79. We screened those publications by title and abstract and excluded 21, leaving 58 screened in full text. We excluded 52 full-text studies for different reasons highlighted in the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) flow diagram. Of six included studies, data were extracted. The PRISMA flow diagram shows the selection of studies (Figure 1).

Characteristics of the Included Studies

The meta-analysis consists of six trials^11-13,17-19 with a total of 364 patients who had procedures necessitating OLV. Patients were randomized to receive either VS-DLT or c-DLT in all studies. Tables 1 and 2 provide baseline characteristics and a summary of the included studies. The risk of bias summary is in (Figure A1 in Appendix).

Outcomes

Intubation Time

Intubation time is measured from the introduction of the laryngoscope blade till visual confirmation of the DLT position.¹⁷ Five studies^11,13,17-19 assessed the intubation time (n = 311 participants), and the overall MD showed a statistically significant difference between the experimental and control groups favoring the VS-DLT to c-DLT (MD = –90.01; 95% confidence interval, –161.33 to –18.69; P = 0.01) as shown in (Figure 2). The pooled studies were heterogeneous (P < 0.00001; I² = 98%). We performed a leave-one-out sensitivity analysis, which did not resolve the heterogeneity, and no single study contributed most to the heterogeneity.

Four studies reported dislodgement occurrence during positioning^11,13,18,19 (n = 240 participants). There was no significant difference between the two groups (OR = 0.46 [0.18, 1.17]; P = 0.10), as shown in (Figure 3). The pooled studies were homogeneous (P = 0.16; I² = 42%).

Four studies^11,13,18,19 reported the dislodgment occurrence time during the surgery (n = 240 participants). The overall OR showed that there was no significant difference between the two groups (OR = 1.97 [0.74, 5.29]; P = 0.18), as shown in (Figure 4). The pooled studies were homogeneous (P = 0.90; I² = 0%).

Lung collapse was assessed as follows when the chest wall was opened: fully collapsed lung (excellent quality of lung deflation), non-collapsed lung with no evident ventilation, or fully ventilated lung (poor quality of lung deflation).¹⁹ Four studies^11,13,18,19 reported the quality of lung deflation (n = 240 participants). There was no significant difference between the two groups regarding the ratio of patients with excellent lung ventilation (OR = 0.82 [0.22, 3.05]; P = 0.77), as shown in (Figure 5). The pooled studies were homogeneous (P = 0.19; I² = 36%).

The incidence of sore throat was assessed in four studies^11,17-19 (n = 261 participants). The meta-analysis showed that there was no significant difference between the two groups (OR = 0.96 [0.44, 2.09]; P = 0.91), as shown in (Figure 6). The pooled studies were homogeneous (P = 0.31; I² = 17%).

Three studies^11,13,19 reported the effect of the VS-DLT on the frequency of the use of FOB compared to the standard method (n = 201 participants). The results revealed that the use of FOB among the VS-DLT group was significantly lower than in the c-DLT group (OR = 0.01 [0.00, 0.07]; P < 0.00001), as shown in (Figure A2 in Appendix). The pooled studies were homogeneous (P = 0.27; I² = 24%).

Three studies^17-19 reported the hoarseness of voice as an adverse effect of VS-DLT compared to c-DLT. The pooled analysis showed no significant difference between VS-DLT and c-DLT (OR = 1.05 [0.49, 2.23]; P = 0.90), as shown in (Figure A3 in Appendix). The pooled studies were homogeneous (P = 0.48; I² = 0%).

Two studies^11,13 investigated the presence of secretions during the surgery (n = 130 participants). The presence of secretions was significantly higher in the VS-DLT group compared to the c-DLT group (OR = 4.24 [1.96, 9.13]; P = 0.0002), as shown in (Figure A4 in Appendix). The pooled studies were homogeneous (P = 0.43; I² = 0%).

The effectiveness of clearance of secretions was examined in two studies^11,13 (n = 53 participants). The overall OR revealed that there was a non-significant difference between the two groups (OR = 0.15 [0.02, 1.35]; P = 0.09), as shown in (Figure A5 in Appendix). The pooled studies were homogeneous (P = 0.75; I² = 0%).

Discussion

Summary of the Outcomes

Our study includes six RCTs involving 364 participants split into two groups. The first group consists of OLV patients utilizing the VS-DLT, while the second group utilized the c-DLT. There was a significant difference between the two groups for the intubation time, the frequency of FOB use, and the number of times secretions were encountered during VS-DLT compared to the c-DLT. However, there was no significant difference between the two cohorts regarding the effectiveness of clearance of these secretions. In the meantime, certain complications remained negligible, such as dislodgement during patients’ positioning or the procedure itself. Notably, there was no difference between the two groups regarding the excellent quality of lung collapse.

Explanation of the Outcomes

Our analysis model showed that the time required for tracheal intubation using VS-DLT was significantly shorter than that for c-DLT. Onifade et al.¹³ attributed this difference because intubation with the VS-DLT typically does not necessitate using a second FOB to verify proper tube placement. Levy-Faber et al.¹⁷ addressed the same: the direct visualization of the distal tip of the DLT in relation to carina does not necessitate verification using the FOB. This marginal improvement in the time of intubation is beneficial in patients at risk of rapid desaturation.

A significant concern in this outcome is heterogeneity. Leave-one-out sensitivity analysis did not resolve it, and no single study contributed most to this heterogeneity. A possible explanation of this heterogeneity is the variability among different studies regarding the definition of intubation time, and we noticed that some studies clearly defined the timing for intubation, but others did not. Also, the definition of time to intubation was inconsistent; one study defined the time to intubation as the time from laryngoscopy blade introduction to visual verification,¹⁷ but a second study defined the time to intubation from blade introduction to DLT confirmation by auscultation.¹⁸

Dislodgement did not differ significantly between the two cohorts either during the patient positioning or surgery. However, the VS-DLT, compared to c-DLT, has many advantages regarding displacement and the need for tube repositioning; the camera allows for continuous visualization of the airway, which can warn the anesthetist of the possibility of displacement and early detection once it happens. Palaczynski et al.¹⁹ pointed out that there is a high rate of complications if there is no rapid detection with early intervention by tube repositioning. This was addressed by Inoue et al.²⁰, as prolonged malposition can disturb ventilation, causing hypoxia. The strength point here is that successful repositioning by tube advancement or withdrawal can be done under vision without the need for FOB; this will prevent complications.^11,18

Both VS-DLT and c-DLT provided excellent lung collapse and did not interfere with the surgical field, as both systems are more or less similar to each other and thus provide comparable results for lung deflation. The incidence of sore throat and hoarseness of voice was comparable between the two cohorts since the size and mechanical properties of the two different devices are similar.¹⁹ Tube size is the leading cause of postoperative sore throat and hoarseness of voice.²¹ However, several other confounding factors may contribute to a higher incidence of sore throat, as pointed out by Schuepbach et al.¹⁸; this includes the skills of anesthetists performing intubation, cuff pressure, and prolonged or forceful laryngoscopy.

The results of FOB use are statistically distinctive, favoring VS-DLT, as it allows continuous vision of the carina, permits vision of any tube displacement in real-time, and allows correcting it without the need for FOB.²² Because the airway is not always readily accessible to the anesthesiologist, particularly during the robotic, spine, or prone procedures, continuous visualization adds a layer of safety by allowing the physician to check the precise installation of the endobronchial tube.^11,13 As observed by Heir et al.¹¹, the most common reason for FOB use in the VS-DLT was poor picture quality due to inadequate secretion clearance.

The number of times secretions were encountered was significant for VS-DLT compared to the c-DLT. Since the external monitor makes noting secretions much easier than it would be with a DLT, Heir et al.¹¹ concluded that it is most likely a reporting bias. However, there was no statistical difference between the two groups regarding the effectiveness of the clearance of secretions. One reason secretions were never a problem in c-DLT was that the VS-DLT’s implanted camera is permanent, while the FOB is readily removed and cleaned.^11,13 However, VS-DLT also features an integrated flushing system that enables intratracheal cleaning of the camera lens if the lens becomes obstructed by secretions or blood, allowing the anesthetists to clear secretions in the vast majority of cases.¹³ Suctioning the large secretions can be difficult via the small calibre FOB suction port, necessitating the use of larger catheters blindly. Because the membranous and cartilaginous trachea is prone to injury from excessive or blind suctioning, the external monitor’s visibility in VS-DLT can aid in guiding suctioning, preventing unnecessary tracheal stress.¹¹

Compared to the approximate 300 USD cost of the VS-DLT, the regular DLT has a direct cost of approximately USD 150 as per Schuepbach et al..¹⁸ The expense of maintenance and cleaning a flexible bronchoscope is high and likely approaches 100 USD every instance. Larsen et al.¹² used an analytic decision model to analyze the effects and costs of using VS-DLT as an alternative to a c-DLT with a reusable bronchoscope in the Danish healthcare system. The base-case study found that using VS-DLT was more cost-effective, and sensitivity analysis confirmed the consistency of the findings and demonstrated that VS-DLT was more efficient and cost-effective.¹² Recent cost estimates imply that VS-DLT could be more expensive per procedure¹³; thus, there is no unanimity on VS-DLT versus c-DLT cost effectiveness.¹²

Strength Points

According to our knowledge, this is the first meta-analysis on this topic. We included only RCTs, considered the best design for controlling bias, and can measure multiple outcomes to obtain the best evidence quality in the literature. We reported nine outcomes aiming to detect any potential advantages or disadvantages of VS-DLT based on all the evidence already available.

Limitations

A few studies do not show the actual difference between the two groups. Based on included studies, two studies showed an unclear randomization process. Investigators were aware of the experimental and the control group, and it was difficult to blind them, which affected the outcomes measurements negatively, and all studies showed a high risk of bias in the measurement of the outcomes.

Recommendations

More research is required to provide enough context for the results. More economic analysis is needed to determine if VS-DLT is cost-effective in broader or worldwide clinical settings. Future research should standardize the nomenclature among different outcomes.

Conclusion

As the number of minimally invasive combined laparoscopic and thoracoscopic procedures for upper gastrointestinal surgery has increased, OLV has expanded its scope to encompass procedures in other specialities. This study included 364 patients separated into two groups. We found that VS-DLT was substantially favored over c-DLT, providing a shorter time for intubation, less FOB usage, and fewer number of times secretions were encountered. Even though VS-DLT shows promise for OLV, it cannot replace the occasional requirement for FOB use. As these devices differ amongst institutions, additional cost evaluations may reveal more persuasive economic considerations for using a VS-DLT. Additional multicenter trials with anesthetists of diverse skill levels are required to analyze the usage comparability of both devices in greater detail.

Conflict of Interest

All authors do not have any conflict of interest to declare.

---

References

Appendix