Video-Assisted Thoracoscopy: Multiportal Uniportal




Video-Assisted Thoracoscopy: Multiportal Uniportal



Zerrin Sungur, Mert Şentürk



Abstract


Video-assisted thoracoscopic surgery (VATS) is beneficial for patients; but for the anesthetist, it can be even more difficult than an open thoracotomy. General challenges of airway management, one-lung ventilation, fluid management remain, with some additional conditions, like “no continuous positive airway pressure in VATS,” or “delayed treatment of bleeding.” Anesthesia for thymectomy in myasthenic patients, or an anesthetic approach in “nonintubated” VATS are some of the specific conditions. Analgesia is also still a challenge; new peripheral blocks offer new horizons.


Keywords


Video-assisted thoracoscopic surgery; one-lung ventilation; airway management; myasthenia gravis; nonintubated VATS; postoperative analgesia



Introduction


Video-assisted thoracoscopic surgery (VATS) is one of the major innovations in surgery. Within less than 30 years after its modern introduction, almost all of the operations, with only few exceptions, can be performed via VATS. It provides several benefits for the patients, as well as several challenges for the anesthetist. It is an “intentionally created” pneumothorax followed by the introduction of instruments into the cavity to perform the operation.



History


Though thoracoscopic surgery has prospered in the 1990s in terms of surgical spectrum and variability of patients, its history dates back to 19th century. Bozzini was the first to describe a primitive endoscope with a thin cannula and mirrors illuminated by candle in 1806 and named it “Lichleiter,” which is still exhibited in Josephinum of Vienna. However, this device was not largely adopted by the medical community because of low image quality and cumbersome access. Later, modifications, such as introduction of a lens to focus with a direct light source improved visualization,1 and endoscopes were developed to remove foreign bodies from the esophagus (esophagoscope) or diagnose and treat diseases of the bladder and urethra (cystoscope).


The ontogenesis of thoracoscopic procedures overlaps with the history of discovery and treatment of tuberculosis disease. Artificial pneumothorax was suggested and later published about in an Italian journal2 for phthisis by Forlany within the same year of the discovery of tuberculosis bacillus. The technique was based on insertion of a needle via and the anterior axillary line and insufflation of air or nitrogen, but the presence of adhesions in the chest wall seemed to limit the expected benefit of the technique. An internist in Sweden, Hans Christian Jacobaeus, who performed the initial step in thoracoscopic history by dividing these adhesions using the two cannula technique via fluoroscopy guidance: the first cannula was the thoracoscope and the second was galvanocautery to be heated at red glow. Ironically, the aforementioned first phases of thoracoscopy were established by pulmonologists and not by surgeons. However, thoracoscopic procedures soon lost their popularity, and thoracoscopy became mostly limited to diagnostic practices with the introduction of antituberculosis chemotherapy in the 1940s. Its rediscovery in trauma surgery was heralded by Branco from Brazil in the 1940s.1 During the transition period, Bloomberg from the United States continued to perform thoracoscopic procedures and shared his experience at the end of the 1970s. Meanwhile, in Europe, thoracoscopy was not totally abandoned and was applied in the treatment of empyema. During this time, scopes and staple devices further evolved yielding a breakthroughs in minimally invasive surgery, and the once-forgotten technique was revived. The thoracoscopic lobectomy was eventually performed in the 1990s, redefined as VATS, by Roviaro from Milan.3 Indications have extended beyond the diagnostic issues to achieve a surgical spectrum of thoracoscopic procedures of extended lung resections, including mediastinal mass, thoracic trauma, thoracic wall abnormalities, and esophageal operations. Today, VATS has evolved to subxyphoid, uniportal, or robotic procedures with the goal to minimize surgical injury.


Thoracoscopic surgery today is implemented worldwide. In the 1930s, Dr. Nissen, one of the Jewish academicians who left Germany for Istanbul University before the Second World War, has contributed to the advancement of thoracic surgery in Turkey. Historical progress was similar, starting with surgical treatment of tuberculosis in the 1940s to VATS in the late 1990s,4 and robotic and uniportal VATS in the 2010s.5 Today, in the institution of the authors, and in most other institutions worldwide, the majority of the thoracic surgical procedures are performed with VATS.



Techniques of Video-Assisted Thoracoscopic Surgery and Its Advantages


The classical (almost historical) approach of VATS is performed with the standard three-port (up to five ports) technique (camera port, utility port, and posterior/grasping port), in different degrees of lateral position. A video camera is introduced to allow for direct visualization of the entrance of trocars into the thorax.


Unlike laparoscopic procedures, insufflation of carbon dioxide (CO2) into the hemithorax to enhance the view of the working-space (better collapse of the lung; less adhesion etc.) is an uncommon approach in thoracoscopic operations; drawbacks exceeding the evidence of benefit. Insufflation of CO2 into the closed cage of the hemithorax can be associated with hemodynamic instability, hypercarbia, and hypotension. Although non routinely done, more spread during robotic thoracic procedures, the intrathoracic insufflation pressure should be kept below 10 cm H2O.


Following its introduction to clinical practice, VATS has been shown to be a reliable method to safely replace—almost—every possible open procedure: “medical thoracoscopies” are performed almost exclusively by pulmonologists for diagnostic purposes; “surgical thoracoscopies” can be diagnostic, where the traditional “diagnostic mini-thoracotomy” has become almost historical, or therapeutic. Because thoracoscopy is a less invasive approach, it has permitted that patients who were not considered to be operated because of their severe comorbidities, are now offered major resections.



Video-Assisted Thoracoscopic Surgery Versus Open Thoracotomy


Contrary to conventional incisions—such as posterolateral thoracotomy—port holes require smaller incisions which would be associated with reduced inflammatory response, better respiratory mechanics, improved respiratory muscle recovery, and certainly lesser pain. Thoracoscopic procedures have become more frequently comprising a wide range of procedures and represent a reliable minimal invasive alternative for high-risk patients.


Initial reports highlighted benefits of VATS in reducing overall complications and decreasing hospital stay.6 Furthermore, the thoracoscopic approach was found to be more favorable in terms of intensive care unit (ICU) stay time and postoperative pneumonia despite preoperative comorbidities.7 In several studies, it was shown that VATS minimized complications and enhanced the quality of life in the postoperative period,8 with less postoperative pain,9 better pulmonary function outcomes,10 shorter overall hospital length of stay, and faster return to normal activities.11,12 In 2010, the American College of Surgeons Oncology Group published data of approximately 1000 patients and found that thoracoscopic lobectomy was associated with lower pulmonary complications (atelectasis, chest tube drainage) and shorter length of stay.13 In 2016, the European Society of Thoracic Surgeons reported results from 235 centers which included 5500 patients (selected among 26,000 according to propensity score).14 Major cardiopulmonary complications were significantly lower in the VATS group compared with the thoracotomy group (15.9% vs. 16.9%; P = .0094). Length of stay was shorter among the thoracoscopic group as expected (P = .003). Mortality at discharge was also lower in the VATS group, which, however, needs to be cautiously commented according to authors because of some missing data. A more recent trial by Nwogu et al. has compared VATS with open thoracotomies as length of stay (LOS) for primary outcome. The VATS group had significantly lower LOS (5.4 vs. 8 days; P < .001). Moreover, incidence of complications was consistent with the primary outcome favoring the VATS group (6% vs. 16%; p = .0001). Thoracoscopic surgery is associated with reduced injury, stress response, and may enhance recovery of patients in thoracic surgery. The short-term outcome appeared favorable for thoracoscopic surgery.15


In the recently published: “Guidelines for enhanced recovery after thoracic surgery (ERATS),” VATS was recommended for lung resection for early-stage lung cancer with a “high” evidence level and “strong” recommendation grade, stating that “the benefits are even more marked in patients with poor respiratory reserve.”16


Long-term results are controversial; studies show either similar results of both approaches, or better results for VATS in terms of survival. Sugi et al. reported a similar oncologic outcome in VATS compared with conventional lobectomy for the following 5 years.17 Similarly, Whitson et al. did not find any difference in survival between thoracoscopy and thoracotomy.7 Recently, one center study by Oda et al. in patients with early lung cancer, reported better 5-year survival in patients undergoing thoracoscopic resection.18 Short-term variables (blood loss, hospital stay, C-reactive protein [CRP] levels) were also significantly advantageous in the thoracoscopy group. The authors speculated that it could be related to lesser tissue damage and inflammatory response screened by CRP values. Other studies confirm that the long-term (5 years) survival was better with VATS when compared with open surgery for early-stage lung cancer19,20 (Fig. 31.1). Another recent study comparing VATS to open thoracotomy for cT1–T2 N1 M0 nonsmall cell lung cancer (NSCLC) showed that VATS had no significant difference in long-term survival, with shorter LOS and similar nodal upstaging rates, considering it suitable for the treatment of NSCLC.21


image
• Fig. 31.1 Kaplan-Meier curve of the survival after open thoracotomy or VATS.CI, Confidence interval; HR, hazard ratio; VATS, video-assisted thoracoscopic surgery. (From Al-Ameri M, Bergman P, Franco-Cereceda A, et al. Video-assisted thoracoscopic versus open thoracotomy lobectomy: a Swedish nationwide cohort study. J Thorac Dis. 2018;10:34993506.)

Today, VATS is recognized by international guidelines as preferred over thoracotomy for treatment of early-stage NSCLC.22


An interesting retrospective study revealed similar costs for thoracoscopic or traditional lobectomies.23 Operative cost was significantly higher with VATS, whereas total hospital cost was similar with traditional lobectomy, but a shorter stay in the thoracoscopic group and increased patients’ turnover abolished the temporary economic issue of conventional approach.



Uniportal Video-Assisted Thoracoscopic Surgery


In a period of less than 20 years, there has been a rapid evolution in the surgical technique of VATS: the classical three-port approach was initially changed to a two-port strategy, and soon afterwards, there was a trend toward a one-port technique, where the camera was moved to the utility port, the camera’s port was abandoned, and the entire procedure was completed using just one incision. Uniportal VATS was first described in 2001, and then reported for simple procedures, such as lung biopsies and spontaneous pneumothorax in 2005.24


The expansion of the technique was achieved following the developments by Gonzalez-Rivas et al. in the next 10 years, where the technique was used for more complex procedures, such as pulmonary anatomic and complex resections for the treatment of lung cancer.25 This strategy achieves a direct vision of the targeted tissue and of the pulmonary hilum. This fact, together with the accession of parallel instrumentation, achieves an approach similar to the open surgery view and maneuvers, making the surgeons feel more comfortable while operating, compared with other VATS strategies. Today, the technique has been adopted, reproduced, and reinforced by the surgical community; however, it is limited by the significant learning curve.26,27


Compared with conventional VATS, UniVATS has been shown to be beneficial with shorter LOS in the hospital, duration of drainage, and reduced overall morbidity.28 One—instead of three—incision is associated with less inflammation and less pain, leading to reduced postoperative complications, with an overall better outcome. It has been used not only in operations like lobectomy or wedge resection but also in more complicated procedures like pneumonectomy, sleeve resection or tracheal and carinal resections.27


It should be noted that some trials report no difference between uniportal and multiport VATS lobectomy. Perna et al. have compared uniportal video-assisted lobectomy (group A; n = 51) and other video-assisted thoracoscopic lobectomy techniques (group B; n = 55). The median visual analog pain score in the first 3 days did not show statistically significant differences. Likewise, the median morphine use in the first 3 days did not show statistically significant differences. There was no difference in timing to remove the paravertebral catheter and the chest drain and the duration of the postoperative hospital stay. There was no difference in postoperative complications.29 In ERATS protocols, it has been stated that “The number of ports used does not appear to affect outcomes, and so, one VATS approach cannot be recommended over another.”16 As a matter of fact, more and more high quality studies are still necessary to evaluate the potential benefits of this technique. The anesthetic management, including ventilation, for uniportal VATS does not differ from that performed for classical VATS.30



Subxiphoid Uniportal Video-Assisted Thoracoscopic Surgery


The subxiphoid approach began its evolution in 1999.31 First implemented for mediastinal pathologies, in 2014, a subxiphoid UniVATS left upper lobectomy was reported.32 Following that, many procedures, such as wedge resections, segmentectomies, lobectomies, and even pneumonectomies have been performed by this approach. There are two major advantages of this technique: (1) intercostal nerve injury related to the incision and instrumentation is avoided, and (2) it will allow approaching bilateral lesions from a single incision without changing the patient’s position. Avoidance of intercostal nerve injury has been shown to be associated with significantly lower postoperative pain compared with intercostal UniVATS.33



Robotic-Assisted Thoracic Surgery


Robotic-assisted thoracic surgery (RATS) is covered in Chapter 52 in this book in detail. It should be considered as an important step of the rapid changes in the practice of thoracic surgery and anesthesia. A subcostal VATS approach (with or without robotic help) is also one of these promising steps.34



Preoperative Evaluation and Prehabilitation



Preoperative Risk Stratification


Preoperative evaluation with risk stratification and scoring systems are extensively explained in Chapter 8 of this book. Regarding VATS, it should be noted that some systems take also “operation-related” risk factors into consideration (e.g., considering pneumonectomy as “high-risk”); however, to our knowledge, none of these risk stratifications and scoring systems differentiated between open thoracotomy and VATS as different risk factors. The risk of a patient undergoing open thoracotomy with similar comorbidities and extent of resection is higher than the patient undergoing VATS. This part will therefore focus on “common” criteria.


Improvements of surgical techniques and advances in anesthesia have resulted in an overall improved outcome. But at the same time, those improvements allowed patients who previously were not considered surgical candidates to now be offered major resections. These patients are older, with multiple comorbidities which in many cases are uncontrolled or not treatable, making the perioperative period challenging, and probably leading to an increase in postoperative complications and decrease survival.35 Therefore preoperative evaluation and preparation of patients who will undergo a VATS procedure should be revised separately.


Perioperative mortality represents a serious worldwide public health problem. Thoracic surgery deserves special interest because postoperative complications are significantly high (up to 27% in a recent review) (Fig. 31.2).36 Preoperative assessment and screening of high-risk patients must identify the patient that would benefit from optimizing measures. Increase in patient comorbidities and an increase in awareness during the perioperative period is a relatively new topic which is part of the ERAS (enhance recovery after thoracic surgery) guidelines.16 A team approach makes sense for this population while assessing cardiac risk, planning optimizing measures, organizing oncologic follow-up, and judging operability. Thus an experienced team should be composed of a pulmonologist, oncologist, thoracic surgeon, and anesthesiologist as well as the patient and the relatives.


image
• Fig. 31.2 Incidence of postoperative complications after lung resection. Complications affect survival at different times in the postoperative period. ARDS, Acute respiratory distress syndrome; CVA, cerebrovascular accident. (From Pedoto A, Perrino AC Jr. Delayed recovery following thoracic surgery: persistent issues and potential interventions. Curr Opin Anesthesiol. 2019;32:39.)

The first step of preparation can be initiated with cardiac evaluation to determine preexisting risk factors and to treat before surgery. The revised cardiac risk index has been adapted for thoracic surgery (Table 31.1).37 Three to four subgroups are defined in this scoring system as A (0 point), B (1–1.5 points), C (2–2.5 points), or D (>2.5 points); the latter two described as high risk. The incidence of cardiac event varies in groups for A less than 1.5%, for B 5.8%, for C 19%, and for D 23%. The thoracic revised cardiac risk index (ThRCRI) can discriminate high-risk patients—groups C and D38—and may allow for identification of patients who would benefit from additional cardiac evaluation.



Table 31.1




















Thoracic Revised Cardiac Risk Index
  Point
History of coronary artery disease 1.5
Cerebrovascular disease 1.5
Creatinine >2 mg/dL 1
Pneumonectomy 1.5

A subsequent cardiac issue—generally neglected—is right ventricular (RV) function, which remains affected from the second postoperative day to the second month.39 Postthoracotomy impaired RV ejection fraction is a recognized phenomenon usually related to elevated pulmonary vascular pressures but also to reduced compliance. Thoracoscopic surgery compared with thoracotomy offers advantages in terms of RV function in the early postoperative course for elderly patients.40 Not surprisingly, the extent of lung resection directly affects RV changes. Pneumonectomy is found to be associated with more pronounced RV dysfunction compared with lobectomy.41 Further studies are needed to determine the best predictor for preoperative assessment of RV. Natriuretic peptides seem promising in thoracic patients to detect some CV complications, especially for prediction of postoperative atrial fibrillation.42,43


Pulmonary evaluation for lung surgery includes spirometry, diffusion capacity, and exercise tests if needed, as summarized in Fig. 31.3.37 Although patients with low risk can be cleared for surgery, in high-risk patients, cardiopulmonary exercise testing should be considered. In a newly introduced algorithm, a slope of minute ventilation to CO2 output ratio seems promising.44 A slope of more than 34 was associated with increased mortality. In fact, an increased ratio could be explained by respiratory inefficiency and appeared to be associated with increased mortality.45


image
• Fig. 31.3 Risk stratification for thoracic surgery. Note that this algorithm is defined for all thoracic operations, including both open thoracotomies and video-assisted thoracoscopic surgery (VATS). It could be considered that for a patient with similar risk factors, undergoing VATS would be less risky than an open thoracotomy. CPET, Cardiopulmonary exercise testing; DLCO, diffusing capacity for the lung for carbon monoxide; FEV1, forced expiratory volume in one second; ThRCRI, thoracic revised cardiac risk index; PPO, predictive post operative; VO2 max, maximum rate of oxygen consumption; VCO2, carbon dioxide output; VE, minute ventilation; VE/VCO2slope, minute ventilation/CO2 production.



Preoperative Optimization and “Prehabilitation” (See Chapter 9)


Besides risk stratification, the aim of a preoperative evaluation is optimization and rehabilitation. The anesthesiologist as perioperative physician has to manage treatable conditions to reduce complications. The initial measure should be smoking cessation, as it is a considerable risk factor in lung cancer for both short- and long-term outcomes.46,47 Smoking impairs mucociliary ability to remove pathogens or foreign bodies from the airway and alveolar macrophage activity. In a retrospective study performed with more than 20,000 subjects, smoking cessation was found to be associated with reduced in-hospital morbidity and mortality independent of time interval and amount of smoking.48 A prospective study affirmed similar results among thoracoscopic lung surgery patients; with incidence of postoperative pulmonary complications (PPCs) 10 times greater in active smokers compared with never smokers and 2 times compared with ex-smokers.49 Cessation of more than 6 weeks resulted in reduced LOS. However, optimal timing for cessation before surgery has yet to be determined.


Iron deficiency anemia is very common worldwide and affects surgical populations. Screening and treatment of anemia is recommended for expected blood loss greater than 500 mL before surgery. The target value of hemoglobin commonly accepted for preoperative iron therapy is 13 g/dL and replacement is achieved by intravenous (IV) iron if there is a window of less than 6 weeks to surgery.50 In case of chronic inflammation, diagnosis requires additional findings; serum ferritin levels less than 100 mcg/L or transferrin saturation less than 20% can be considered as inadequate iron stores. Anemia has been associated with worse survival in lung cancers.51 On the other hand, transfusion itself was related with early recurrence and shorter survival in a meta-analysis of 23 studies.52 The authors conclude with recommendation of stricter transfusion policy, especially for early stages. Supporting recent results from 15 years’ data of a single center with worse outcome and increased recurrence of blood transfusion.53 The difference seemed to appear with more than one unit of blood transfusion. Patient blood management, a concept that aims to rationalize blood transfusion, should be applied as possible also in VATS operations.


A relatively new issue of optimization is preoperative habilitation “prehabilitation,” which consists of training patients with respiratory or cardiopulmonary exercises before surgery. The expectation is to improve physical performance, to increase exercise tolerance, and to improve health-related quality of life for a well-conditioned patient. Types of exercise are endurance or high-intensity interval trainings (HIIT). The first one consists of moderate intensity efforts and 60 to 120 minutes in daily practice over 6 to 12 weeks. On the other hand, the second one is performed at a high intensity in relatively brief training periods. Licker et al. investigated effects of HIIT and conventional preoperative optimization (nutritional measures, smoking, and alcohol cessation) in patients undergoing lobectomy.54 The training group attained significantly better peak O2 consumption and 6-minute walking values. Pulmonary complications were significantly lower in the prehabilitation group because of decreased incidence of atelectasis. However, composite outcome, death, and in-hospital complications which was the primary outcome, were similar between groups. Moreover, beneficial effects of a rehabilitation program can be more prominent in patients with respiratory impairment during induction chemotherapy.55 Initial reports are encouraging with improved aerobic performance and respiratory volumes. Is this progress sufficient to prevent postoperative complications? An adequately powered randomized controlled trial (RCT) that is presently ongoing multicentric study (INSPIRE) hopefully will provide more concrete information.



Lung Isolation (See Chapters 16,17)


Airway management is a crucial topic of thoracic anesthesia and is covered in different chapters in this book. Here, we aim to inform about specific conditions in VATS operations within a range of general aspects.



History


Historically, lung isolation essays were started with physiologic animal studies by C. Bernard and E. Pflüger in the 19th century. The setup was adapted to volunteers by Loewe and von Schrotter at the beginning of the 1900s, again, for cardiopulmonary physiologic studies.56 Introduction of the endotracheal tube (ETT), by Gale and Waters, followed by the introduction of the double-lumen tubes (DLTs). The 1950s presented the first double-cuffed double-lumen tube described by Carlens. DLTs designed by Robertshaw were introduced first in red rubber in the 1960s; 20 years later, they are marketed as disposable polyvinyl chloride, and are used worldwide. A rubber bronchial blocker (BB) was first used (positioned by radiography) in the 1930s by Archibald.57 The use of the fiberoptic bronchoscope was considerably later in the 1980s and constituted a huge advancement in thoracic anesthesia.



Indications


The historical classification of indications for one-lung ventilation (OLV; namely, absolute vs. relative) is not target-oriented and sometimes confusing. From that historical point of view, every VATS operation should be considered as an “absolute” indication of OLV. Currently, thoracic anesthetists agree on the classification of lung isolation versus lung separation: the isolation of the lungs means a completed “anatomic” sealing (conditions like massive pulmonary bleeding, air leak as a result of bronchopleural fistulae, pneumonia with pus, etc.); whereas the separation of the lung means a “functional” sealing.58 Because most VATS operations require just lung separation and not isolation, both DLTs and BBs can be used. DLT is the most common device used in OLV, but it should be known that in some conditions, BBs can be a more rational alternative (Table 31.2).



Table 31.2



















Comparison of Tools for Lung Isolation

Indications Advantages Disadvantages
Double-lumen tube Lung separation (unilateral abscess or cyst; unilateral hemorrhage; bronchoalveolar fistula; unilateral giant bullae, lung transplantation; bronchoalveolar lavage lung isolation (all other indications of OLV, including all kinds of lung resections, and other operations, such as esophagectomy, orthopedic surgery etc.) Familiarity

Easy insertion


Malposition uncommon


Faster, effective lung collapse


Bronchoscopy possible for each lung (operative or other)


Feasible in absence of bronchoscope


Differential ventilation available if needed

Problematic in difficult airway

Not available for each size


Not suitable for postoperative ventilation


Risk of airway (tracheal or bronchial) trauma

Bronchial blocker (BB) Lung isolation (i.e., the majority of cases undergoing VATS) Patient with tracheotomy

Selective lobar placement


Difficult airway


Pediatric patients


Nasal intubation Postoperative ventilation

Experience required

Malposition more common


Bronchoscope mandatory


Difficult to alternate OLV for each lung (except EZ-Blocker)


OLV, One-lung ventilation; VATS, video-assisted thoracoscopic surgery.



Image




Double-Lumen Tubes Versus Bronchial Blockers (See Table 31.2)


Using the DLTs is the most common method for lung isolation; referred to as the “gold standard” by Cohen59: many anesthesiologists consider it as the easiest method, mainly because they are familiar with it. A left DLT is preferable for the vast majority of thoracic procedures because a right DLT is more difficult to place and it is more complicated to maintain the optimal position to ventilate the right upper lobe. There are some limited indications for use of a right DLT, such as left main bronchial lesions with associated surgery (e.g., left pneumonectomy or sleeve resection) or an external cause of obstruction of the left main bronchus by an aneurysm of the descending aorta.


Available sizes of DLTs for adults vary between 26 Fr and 41 Fr and smallest sizes can be selected in children over 8 to 10 years old. One of the major challenges of a DLT is the lack of an accurate method to select the proper size and also the optimal insertion depth.


*Proper size: For a left-sided DLT, it is recommended to measure the width of the left main bronchus and to choose the largest tube that can fit safely that bronchus60 (Table 31.3). For a right-sided DLT, this issue remains unsolved.



Table 31.3





































Double-Lumen Tubes With Size and Diameters
French Size Double-Lumen External Diameter (Fr) Bronchial Lumen Internal Diameter (mm)
26 8.7 3.2
28 9.3 3.4
32 10.7 3.5
35 11.7 4.3
37 12.3 4.5
39 13 4.9
41 13.7 5.4

*Optimal insertion depth: The depth of the DLT can be most accurately determined with fiberoptic bronchoscopy (FOB). A blind technique could easily be associated with 50% incidence of malposition.61 Formulas based on height have been proposed to estimate optimal DLT depth.62


A major concern regarding DLTs is airway trauma because of tube and stiffness and the larger diameter. Other risk factors are lack of flexibility (especially compared with BB), malposition (and multiple attempts to place), or rotation angle in one study (safer with 180 degrees instead of 90 degrees).63 A new meta-analysis comparing a DLT with BB affirmed that a DLT was more commonly associated with an increase in airway trauma presenting as sore throat.64 However, a DLT had significantly less malposition and was more rapidly inserted with a difference of 1 minute, which may be statistically significant but is obviously clinically irrelevant.


A relative new innovation of DLTs has an embedded camera at the tip of the tracheal lumen. This camera enables a continuous view of the carina and ensures the optimal position of the tube. The authors suggest that these types of DLTs can be a good choice especially for (but not excluded to) robotic VATS procedures, where the approach of the anesthetist to the patient can sometime be limited.



Bronchial Blockers


There are several types of BBs:



Details of these devices are covered in other chapters in this book.


It should be noted that in cases where a lung isolation is indicated, unless absolutely necessary, there is no place for BBs. In clinical practice, in most VATS cases, only lung separation is required; therefore if preferred, BBs can be used. Moreover, there are numerous clinical challenges where BBs have to be preferred to DLTs:



  1. 1. Patients with tracheotomy: in the largest tracheotomy series Arndt, Cohen, and EZ-Blockers were safe and effective.65
  2. 2. Patients with previous lung resections, where a lobar blockade is required.66
  3. 3. Difficult airway: a difficult intubation is even more difficult when using a DLT.
  4. 4. OLV in children: although small sizes of DLT can be used in children, their use is difficult; and only suitable for above 8 to 10 years of age. Uniblocker, and Arndt blockers have pediatric sizes of 5.0 mm.
  5. 5. Use in nasal intubation.
  6. 6. Patients arrived intubated to the operating room and/or planned for prolonged mechanical ventilation after the operation: Specific tube exchangers can also be used to switch from ETT to DLT or from DLT to ETT, but this can be complicated because of edema formation.
  7. 7. Intraoperative new indication of OLV: changing to a DLT may present a challenge.

There is a perception of slower or poor lung deflation with the BB. However, Buissière et al. obtained excellent lung collapse with BB and faster than the DLT group.67 Metaanalysis comparing DLT with BB did not find any difference for both tools in terms of lung collapse, most likely because of diverse evaluation of collapse.64 One possible complication of BBs (rarely also of DLTs) is that the malposition may push the tip of BBs into the stapling line.68 The position of the BB (and of DLT) should be controlled before bronchial stapling, and communication with the surgical team is crucial.


Among these alternatives, the choice would be based on a patient characteristics (airway anatomy, underlying disease, need to protect one lung, etc.), type of surgery (site of lesion, possibility of sleeve resection, need for sequential lung separation), and possible adverse effects of devices. The thoracic anesthesiologists should be skilled in different techniques and should have both in their “tool box”: courses and workshops are organized for these purposes.



Fiberoptic Bronchoscopy


Use of FOB in thoracic anesthesia, and especially during VATS, is crucial:



Although it is strongly suggested to use FOB, it may not be available, especially in hospitals with a low volume of thoracic operations. There can be some hints to avoid the drawbacks, as possible:



  1. 1. DLTs have to be preferred to Arndt, Cohen, and Uniblocker.
  2. 2. EZ-Blocker can be used because the resistance of the Y at the distal tip on carina can be positioned without FOB. In this case, careful auscultation would avoid the possibility that both ends of the blocker have been introduced to the same bronchus.
  3. 3. Position control of DLT should be performed with auscultation: first in two-lung ventilation, followed by the sequential blockade of both lumens.
  4. 4. New, but extensively introduced in anesthesia practice, ultrasound (US) was found to be useful in confirming adequate position of left DLT.71 It is feasible in the intercostal view to distinguish the ventilating lung from the collapsed one. To and from movement of ventilated lung is associated with pleura seen as “lung sliding,” whereas collapsed lung appears with “lung-pulse sign” because of pleural movement with heartbeat.
  5. 5. Electric impedance tomography (EIT) can be used to confirm the correct placement of a DLT.72
  6. 6. Finally, DLT and ETT with an embedded camera (VivaSight®). The DLT has the camera at the tip of the tracheal lumen to monitor the position of the bronchial lumen continuously. The ETT has the camera at the distal tip so that BBs (including the one of the same companies) can be positioned under continuous view.73,74


Total Collapse of the Nonventilated Lung


(Fig. 31.4)


image
• Fig. 31.4 A stapling device about to resect left upper lobe. Total collapse of the lung is necessary to avoid several problems including air leaks, limitations of exposure, removal of the resected tissue through a little hole, etc.

In open thoracotomies, some degree of “partial” collapse can be tolerated by the surgeons. On the contrary, in VATS, a total collapse of the lung is inevitable. Even apneic periods can be necessary to create an immobile surgical area for manipulation in the hilum or mediastinum.


Some maneuvers can help to create a total collapse:



  1. 1. Immediately after starting the OLV, open to air or suction to the lumen of DLT or BB to the nonventilated lung should be applied. A relatively low level of negative pressure (–20 cm H2O) is usually enough to improve the speed and quality of lung collapse. The negative pressure and the suction catheter itself achieve both the suction of air from the lung and the prevention of passive entrainment of air into the lung.
  2. 2. Although it is a general rule to keep the time of OLV as short as possible, it can make sense to start the OLV immediately after the positioning of the patient to the lateral position. This would not require a significantly long time, but can help to achieve a collapsed lung when the trocar enters the thorax. Moreover, this time can also be used for a positive end-expiratory pressure (PEEP)-titration in the patients (see the next part of this chapter). Remember that in “OLV with closed chest,” if the lumen of the DLT to the nonventilated lung is open to atmosphere, so-called “passive paradoxical ventilation” can occur, and a tidal volume (VT) of approximately 130 mL can be inhaled to the nonventilated lung (during expiration).75 This means, starting OLV earlier may lead to a delayed collapse, which can be avoided by applying the suction immediately after OLV.
  3. 3. During two-lung ventilation before OLV, lungs can be ventilated with a fraction of inspired oxygen (FiO2) of 1.0 for a period of some minutes. Nitrogen is the “natural CPAP” of the alveoli preventing/delaying the collapse. Wash-out of the pure oxygen from the denitrogenated lung would obtain a faster and better collapse of the lung. After the initiation of OLV, a recruitment maneuver (RM) to “open” the dependent lung would be necessary; adding some air (if the oxygen saturation [SpO2] >90%) would also prevent further atelectasis of the dependent lung.
  4. 4. To repeat one suggestion in this chapter that the use of CPAP during VATS is limited, however oxygen insufflation without expanding the lung may provide some improvement in oxygenation through apneic oxygenation.


One-Lung Ventilation During Video-Assisted Thoracoscopic Surgery



Challenges of One-Lung Ventilation


Although VATS is associated with better outcomes for the patient, it is by no means an “easier” or “simpler” procedure for the anesthetist, nor less invasive than thoracotomy. In some cases, the challenges of OLV can be even more complicated.


During OLV, one lung is excluded from ventilation, but the perfusion to the nonventilated lung continues, leading to a significant increase in intrapulmonary shunt (Qs/Qt) and consequently a higher risk of hypoxemia. In the 1970s, the incidence of hypoxemia during OLV was assumed to be between 20% and 25%. Therefore the historical (classical) recommendations for OLV have mainly focused on preventing and treating the hypoxemia (Table 31.4).76



Table 31.4






Historical and Current Recommendations for One-Lung Ventilation
4A: Historical Recommendation for One-Lung Ventilation (OLV) (to Avoid Hypoxemia)

4B: Current Recommendation for OLV (to Avoid Hypoxemia and Lung Injury)



CPAP, Continuous positive airway pressure; FiO2, fraction of inspired oxygen; PEEP, positive end-expiratory pressure; RM, recruitment maneuvers; TIVA, total intravenous anesthesia; VATS, video-assisted thoracoscopic surgery.


Several mechanisms (above all, hypoxic pulmonary vasoconstriction [HPV]) cause a decrease of blood flow to the nonventilated lung, resulting in a decreased Qs/Qt. For anesthesia and intensive care practitioners, the knowledge of the basic (patho) physiology of HPV is essential.77 This is also the reason why the historical guidelines suggest the use of IV anesthetics, as inhalational agents are known to inhibit HPV, leading to a further increase in pulmonary shunt.


Today, the incidence of hypoxemia has declined to less than 10%, but it should still be considered as an important challenge of OLV.


In the last decades, a growing number of studies have shifted the attention to lung injury (acute lung injury [ALI]) associated with/induced by the OLV.78 One can assume that the postoperative lung injury would be more likely because of the surgical trauma; however, it has been shown that the degree of radiologic density increase was significantly greater in the nonoperative lung compared with operative lung after lobectomy.79 This finding implicates that the intraoperative ventilation strategy is one of the factors that can lead to postoperative lung injury.


The mechanism of ALI and/or increased inflammation induced by the OLV has been explained recently.78,80 In fact, there are similarities between OLV and acute respiratory distress syndrome (ARDS): OLV can be assumed as a variation of ventilation in ARDS because they both deal with smaller ventilated volumes of lung (baby lung in ARDS, and the one-lung in OLV).81


Consequently, the ventilation strategy during OLV should deal not only with the maintenance of the adequate gas exchange, but also with the protection of the lung: “protect both the lung and its functions.” It should be noted that some methods of “prevention of hypoxemia” can be associated with postoperative ALI; and some methods of “protective ventilation” can increase the possibility of hypoxemia.




Mechanisms of Lung Injury During One-Lung Ventilation


(Fig. 31.5)


image
• Fig. 31.5 Mechanisms of lung injury during one-lung ventilation: application of older recommendations (such as “tidal volume of two lungs into one lung”) can be harmful to the ventilated lung. Note that inflammatory processes also occur in nonventilated lung. PEEP, Positive end-expiratory pressure; VT tidal volume.



Protective Ventilation


The protective ventilation was defined and determined in ARDS patients with a “bundle” of some parameters:



  1. 1. Low VT
  2. 2. Low ventilation pressures
  3. 3. RM
  4. 4. PEEP

This approach is also appropriate in healthy lungs undergoing mechanical ventilation for nonthoracic surgery.86 In this study by Severgnini et al., intraoperative protective ventilation (a combination of RM, low VT, and PEEP)—to both lungs—was associated with an improvement in oxygenation (higher SpO2), fewer alterations on chest x-ray, and a lower “modified Clinical Pulmonary Infection Score” during 5 postoperative days. However, note that during OLV, the classical guidelines controvert to all of the components of protective ventilation in some degree (RM and PEEP diverting the blood flow away from the dependent lung to nondependent; and low VT decreasing the ventilation). Therefore precise changes in the “classical” guidelines have been necessary (see Table 31.4B).


We can assume that the application of the combination of all components of protective ventilation can be beneficial for both oxygenation and lung protection during OLV.87 In healthy lungs, applying PEEP and recruitment maneuver does not improve the postoperative outcome and is even associated with intraoperative hemodynamic instability, as shown in the PROVHILO study.88 The debate about this so-called “permissive atelectasis” approach continues.89 New studies entitled PROTHOR and iPROVE are currently testing the effects of PEEP and recruitment maneuvers during OLV.90



Tidal Volume


The detrimental effects of high VT during OLV are well documented. High VT during OLV produces end-inspiratory lung overdistension, a recognized risk factor of lung injury from parenchymal stretching.78,91,92 Several clinical studies showed that low VT is associated with a lower incidence of postoperative ALI.92,93 Low VT compared with high VT decreases the proinflammatory systemic response.94,95 On the contrary, high VT during OLV induces diffuse alveolar damage.85


Low VT ventilation based on predicted body weight (pbw) should be routinely applied to avoid the use of ­excess VT. The pbw is calculated by a formula based on gender and height. VT should be restricted to 4 to 5 mL/kg pbw. The use of a VT of 4 mL /kg during OLV was associated with less lung water content than with larger VTs of 6 to 8  mL /kg.96


A meta-analysis has reported that low VT was associated with the reduced incidence of PPCs.97 Another recent metaanalysis has shown that the use of low VT can worsen gas exchange but reduces airway pressure. Preservation of postoperative oxygenation and reduction in infiltrates suggest a lung-protective modality with low VT.98 It is understandable that lower VT would lead to a decrease in ventilation (Fig. 31.6, left panel), but this problem can be addressed by adding an appropriate PEEP rather than increasing VT. In fact, it has been shown that low VT without adequate PEEP does not prevent postoperative respiratory complications. In the thoracic surgical patients, Blank et al. analyzed the data (medical records and the Society of Thoracic Surgery database) for postthoracic procedure complications. They found that a VT of 8 to 9 mL/kg was associated with fewer PPCs. In the large proportion of the patients, the large VT during OLV was inversely propositional to the incidence of respiratory complications.99 Thus use of physiologic VT may represent a necessary, but not independently sufficient, component of lung protective ventilation (LPV).99 This finding leads again to the recent question of how the different components of LPV should be combined to achieve the best results.


image
• Fig. 31.6 Effects of different tidal volumes and positive end-expiratory pressure (PEEP) on ventilation and lung injury: mechanical ventilation is associated with a decrease of functional residual capacity (FRC) so that the closing capacity (CC) can exceed the FRC. This would lead to a decrease in ventilation (only the grey area above the CC [dashed line] can contribute to ventilation) and to so-called cyclic opening-closing of alveoli. Increasing the tidal volume (left panel) can just improve the ventilation but cannot prevent the cyclic opening-closing of the alveoli (which in turn can lead to “atelectotrauma”). Instead, (right panel) application of an appropriate PEEP can both improve the ventilation (enlarged grey area) and prevent the atelectasis and atelectotrauma. However, this approach can also lead to exceed the limit of overinflation (dotted line), especially in upper zones of the ventilated lung: overinflation is another cause of lung injury. TV, tidal volume.

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Oct 6, 2021 | Posted by in ANESTHESIA | Comments Off on Video-Assisted Thoracoscopy: Multiportal Uniportal
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