2Approaches to the thoracic cavity

2.1Introduction

2.2Thoracotomy

2.2.1Anterior thoracotomy

Anterior thoracotomies are mainly used to control emergency situations. This refers to both cardiac emergencies and severe lung bleeding, such as after penetrating trauma. Anterior thoracotomy facilitates access to both ventricles of the heart and to the descending aorta. Life-threatening lung bleeding may be controlled by hilar clamping via this approach. Moreover, anterior thoracotomy is widely used in lung transplantation. However, these indications are not within the scope of this book. Hereafter, posterolateral thoracotomy and the lateral approaches will be discussed in more detail.

2.2.2Posterolateral thoracotomy

Posterolateral thoracotomy provides superb exposure of the organs within the ipsilateral hemithorax. Though posterolateral thoracotomy is associated with more extensive tissue damage and supposed to contribute to negative postoperative sequelae [1], there is still uncertainty about the optimal location of the thoracotomy [1]. Standard posterolateral thoracotomy requires division of the latissimus dorsi muscle (LD), whereas the serratus anterior muscle (SA) can be mobilized without division. Although functional drawbacks of LD division are negligible, the loss of a major muscle for potential chest wall reconstruction in the future should be taken into consideration. In order to preserve the integrity of the LD a latissimus sparing thoracotomy has been described. The muscle is mobilized by blunt dissection and then retracted allowing for a nearly similar exposure of the respective hemithorax. During dissection of the LD care is taken not to divide penetrating vessels. An additional dissection of the inferior border of the SA, after retracting the LA posteriorly, allows for a total muscle sparing thoracotomy within the third to 7th intercostal space [2]. Despite a slightly longer operation time the muscle sparing approach potentially provides several advantages, such as better lung function in the early postoperative period with reduced need for opioids and less musculoskeletal sequelae.

A variety of musculoskeletal sequelae are attributed to thoracotomies, in particular to posterolateral thoracotomy, in younger children: weak elevation of the ipsilateral shoulder, winged scapula secondary to injury of the long thoracic nerve, thoracic asymmetry secondary to atrophy of the SA, fusion of ribs and to some extent thoracic scoliosis. An association between thoracotomy at a young age and scoliosis is discussed, especially in older publications. However, scoliosis may be associated with the underlying diseases, rather than to the thoracic incision itself. Concomitant spinal deformity in patients with esophageal atresia or an extensive fibrotic process due to esophageal leaks and the necessity of several thoracotomies in patients with tracheoesophageal fistulas could serve as examples. In contrast, chest wall resection is associated with a significant risk for scoliosis development. This is especially true for rib resection involving the fifth or more cranial ribs. A comparable risk exists in case of rib fusion following thoracotomy. However, a thoracotomy with uneventful postoperative healing does not seem to be associated with a higher risk of scoliosis [3].

2.2.3Lateral muscle sparing thoracotomy (anterolateral/anteroaxillary thoracotomy)

Recent research reveals evidence that higher pain scores after posterolateral thoracotomy compared to muscle sparing lateral approaches are triggered by more severe nerve damage [4]. Therefore, these neurophysiologic investigations support the authors preference for lateral/anterolateral approaches. A variety of different muscle sparing lateral approaches has been described, such as vertical thoracotomy. In fact, main differences are related to the angle and to the length of the skin incision. Despite the modern paradigm “small cut – big surgeon”, a too small skin incision should be avoided to prevent injury of the skin. Especially in case of excessive usage of the retractor, or even two retractors, impairment of skin healing is likely to occur. Landmarks for the skin incision in conventional lateral thoracotomy is a point somewhat above the inferior angle of the scapula and the inframammary crease (Fig. 2.2.1). The anterior border of the latissimus dorsi more or less predetermines the dorsal margin of the soft tissue preparation. Mobilization and dorsal retraction of the latissimus dorsi contributes little to extension of the approach, since the long thoracic nerve lies beneath the anterior border of the latissimus dorsi and injury to the long thoracic nerve should be avoided. To gain better exposure of the intrathoracic organs a steeper incision line is recommended. A gradually steeper incision results in anterolateral, anteroaxillary or vertical thoracotomies (Fig. 2.2.1). For vertical thoracotomies the skin incision follows the posterior axillary line slightly posterior to the anterior border of the LD.

Beside a better exposure of the intrathoracic organs, a steep incision line and according line of soft tissue preparation has another substantial advantage. In young female patients care must be taken to avoid breast and pectoral mal-development [5]. This risk can be limited with a steep line of the skin incision followed by meticulous preparation of the pectoralis major (Fig. 2.2.1), provided a thoracotomy not higher than in the fourth intercostal space. However, a higher thoracotomy is rarely necessary.

Alternatively, for younger children from birth until about 8 to 10 years the approach through the axillary skin crease (muscle sparing axillary skin crease incision (MSASCI) represents a promising option [6]. Especially in neonates and young infants this approach allows for a comprehensive operational exposure for a wide range of procedures including lower lobectomies [6]. In older children good access to the lung and the mediastinum via the third or fourth intercostal space is still possible.

Fig. 2.2.1: Schematic diagram of skin incisions for different muscle sparing lateral approaches. A: conventional lateral thoracotomy; B: anterolateral thoracotomy; C: anteroaxillary thoracotomy; D: vertical thoracotomy. LD, latissimus dorsi muscle; PM, pectoralis major muscle; LTN, long thoracic nerve.

2.2.4Closure of the thoracotomy with regard to postoperative pain

The appropriate technique of thoracotomy is the first step also in terms of avoiding post-thoracotomy pain syndrome (PTPS). However, closure of the thoracotomy seems of paramount importance regarding acute postoperative pain as well as long-term sequelae. The treatment of the PTPS is challenging even in the hands of specialized pain experts and with multimodal treatment schedules. Due to the difficulties in objectifying pain, data concerning the incidence of PTPS and the benefit of prophylactic and therapeutic measures strongly vary. In fact, thoracotomy is one of the surgical procedures with the highest rates of chronic postoperative pain. The incidence is as high as 30% or even 50% in adult patients. In children, acute postoperative pain plays a more prominent role while chronic pain is less common. The precise pathogenesis of PTPS is still under debate. It can be assumed with a high degree of certainty that both neuropathic and myofascial pain components play a decisive role. Actually, different factors contribute to an elevated risk of PTPS:

Different technical alternatives for the re-approximation of the ribs aiming at reduced long-term pain have been described (Fig. 2.2.2). In the edge closure technique the suture is placed between the caudal edge of the distal rib and the related neurovascular bundle. For safe preservation of the neurovascular structures usage of a large blunt needle is recommended. Before suturing the inferior edge of the rib and the back of the rib are carefully freed from intercostal tissue. Especially in infants and smaller children the distal suture may be placed subperiosteally (Fig. 2.2.2). Intracostal suture technique represents a third method to prevent strangulation of the neurovascular bundle beneath the distal rib (Fig. 2.2.2). The sutures are placed through small holes drilled through the bony part of the lower rib or of both ribs. The double edge technique allows for potential protection of both neurovascular bundles involved in a thoracotomy (Fig. 2.2.2). The sutures are placed through the thin area between neurovascular structures and the lower rib and similarly between neurovascular structures and the upper rib. Harvesting an intercostal muscle flap before inserting the retractor is another way to reduce the mechanic alteration of the upper and the lower intercostal neurovascular bundles.

For all the above mentioned techniques a significant advantage regarding reduced acute and/ or chronic postoperative pain could be demonstrated in case series or even small randomized trials. However, the benefit under controlled conditions could not be proven for larger series or in routine surgical practice. Therefore, it is difficult to give a definitive generally valid recommendation. Since post-thoracotomy pain syndrome is one of the major concerns in thoracic surgery, any effort should be made to reduce the risk of chronic pain through optimal closure of the thoracotomy. We feel that appropriate analgesia within the early postoperative period is of great significance. Moreover, we apply local anesthetics into the intercostal space prior to the incision. The concept behind this is a potential reduction or even elimination of the pain memory.

Fig. 2.2.2: Re-approximation of the ribs after thoracotomy – technical variants aiming at reduced impairment of the neurovascular bundle (NB): A – pericostal; B – edge technique; C – double edge technique; D – transcostal (drilling holes through the rib).

A second “pain issue” is the technique of opening and closing the intercostal space. Practising in adult thoracic surgery I observed a dramatic decrease in postoperative pain syndrome since I abandoned mid-line intercostal muscle incision with subsequent pericostal reconstruction on either side of the ICS with 4 to 5 thick single sutures. Often, in repeat surgery the respective ICS was blocked by substantial synossification of the ribs, hardly allowing for repat access to the thoracic cavity through the ICS of previous surgery.

2.3Sternotomy

2.3.1Median sternotomy

To avoid healing disorders of the sternum particular care should be taken to divide the sternum exactly in the midline. The midline can be easily identified by palpating the sternal borders with two fingers and marking the periosteum with electrocautery. Electrocautery is used for the division of the periosteum. The direction of sawing can be left to the surgeon’s preference, since according to the literature there is no evidence to favor either direction [7]. However, before sawing from cephalad to caudad, division of the interclavicular ligament is essential. Pulling the sternal saw upwards (from dorsal to ventral) helps to avoid injury to vessels located at the backside of the sternum, such as the brachiocephalic artery and innominate vein. Deflating the lungs by disconnecting the ventilator prior to sawing is standard of care particularly in cardiac surgery. This procedure is believed to avoid accidental pleurotomy and hence to facilitate postoperative recovery. However, according to the current literature this measure cannot be supported [7]. Interestingly, the rate of inadvertent pleurotomy seems to vary significantly from surgeon to surgeon [7]. Sternopericardial ligaments should be divided before further opening of the retractor in order to reduce tension and to avoid unintended opening of the pericardium and the pleura. Periosteal bleeding is controlled by pinpoint cautery. Excessive electrocautery may interfere with sternal healing. If bone wax is applied to treat profuse bleeding from the bone marrow, it should be used sparingly since bone wax is known to interfere with the healing process. Alternatively, vancomycin paste can be used.

Cervico-sternotomies allow a safe exposure of tumors involving the thoracic inlet, such as ganglio-neuromas localized within the upper third of the posterior mediastinum (Tab. 2.3.1).

Tab. 2.3.1: Types of sternotomy and related non-cardiac exposure.

2.3.2Partial median sternotomy (hemisternotomy, upper sternotomy)

The skin incision extends from the sternal notch down to about 2 cm below the angle of Louis. For the division of the sternum we prefer a sternal saw. The sternum is divided from the top down to usually the third intercostal space (Fig. 2.3.1, Tab. 2.3.1). Depending on the specific clinical situation, the sternotomy may extend to the second or sometimes even to the fourth intercostal space. The L-shaped sternal division is completed to the left or more often to the right side again depending on the concrete underlying pathology. It is also possible to omit the lateral sternal incision resulting in a so called I-shaped partial median sternotomy. Even if the sternum is divided down to the fourth or fifth intercostal space, this approach allows access almost exclusively to the heart and the aorta.

Fig. 2.3.1: Schematic diagram of different variants of partial sternotomy: (a) – L-shaped manubriotomy, (b) – inversed T-shaped manubriotomy, (c) – partial upper L-shaped sternotomy, (d) – partial upper I-shaped sternotomy.

The manubriotomy is a special version of the partial upper sternotomy. Usually, a lateral extension of the sternotomy is carried out in the second intercostal space. In older children, this allows for a 3 to 4 cm exposure width with an L-shaped incision (Fig. 2.3.1, Tab. 2.3.1) and for about 6 cm with bilateral inversed T-shaped incision (Fig. 2.3.1, Tab. 2.3.1). Examples for organs or pathologies approachable through the different sternotomy variants are summarized in Tab. 2.3.1.

2.3.3Closure of the sternotomy

Particularly in children, sternotomy closure using absorbable sutures, such as polydioxanone sutures, provides excellent results. Most studies, including several hundred pediatric patients from newborn to 17 years of age [8], confirmed good sternal stability. Advantages of these sutures compared to stainless steel wires are less chronic pain and discomfort as well as absence of an inflammatory reaction. The use of a continuous suture, figure of eight sutures or simple interrupted sutures is subject to the surgeon’s preference. Due to a suspected better distribution of the sharing forces figure-of-eight sutures are recommended by some authors [8]. Even if less common in thoracic surgery, the use of sutures facilitates the approach in case of emergency re-do sternotomy.

Carefull repair of the linea alba is recommended to avoid incisional hernias. Moreover, paraxiphoid extension of the sternotomy is believed to contribute to a lower incidence of incisional hernias.

2.3.4Extended approaches

In case of tumors involving the cervicothoracic junction or huge mediastinal tumors more extensive surgical approaches may be required such as “trap-door” and “clamshell” incisions [9] or the transmanubrial approach (TMA) [10]. Since these approaches do not fall within the scope of this textbook, the readers’ attention is drawn to the respective specialized literature. According to the authors experience the transmanubrial approach allows for excellent exposure the neurovascular structures of the cervicothoracic junction with minimial osteomuscular trauma.

Jens Dingemann, Benno Ure

2.4Video-assisted thoracoscopic surgery (VATS): Development of the operative technique

2.4.1Introduction

Utilization of thoracoscopy has been described as early as 1910. Jacobeus [11] used a cystoscope inserted through a rigid cannula to access the pleural cavity. In a patient with pulmonary tuberculosis, pleuropulmonary adhesiolysis was performed and complete lung collapse was achieved, representing the treatment of choice in these times. Only few years later (1921), the first patient series of more than 100 patients was published by the same author [11].

Over subsequent decades, the acceptance of thoracoscopy was limited and mainly diagnostic procedures were performed. The first thoracoscopic operations in children were described in the late 1970’s. Due to the limited availability of equipment suitable for minimally-invasive procedures in children, the number of procedures was still very low and mainly biopsies of intrathoracic masses were performed.

Along with the advent of laparoscopy in adults and children from the early 1990’s on, VATS developed as an emerging technique and was soon employed for more advanced diagnostic and therapeutic thoracic procedures. Today, improved optical devices, small instruments and sealing devices suitable for operating in confined spaces allow most sophisticated operations even in infants and newborns.

Why VATS?

The potential of improved cosmetic results, when compared to the corresponding open operation is a common advantage VATS shares with other minimally invasive approaches. The potential avoidance of rib fusion, scoliosis and chestwall deformity make the argument for VATS even more compelling. In a recent follow-up study investigating 62 infants, we have shown that the Manchester scar assessment scores and patient’s satisfaction were in favour of VATS as compared to thoracotomy. Furthermore, chest asymmetry in the horizontal plane was significantly less frequent after VATS, the incidence of scoliosis was lower after VATS and the intercostal spaces of the operated hemithoraces were narrower after thoracotomy [12].

Additionally, the technical advantages of the thoracoscopic operation including excellent visualization due to the optic magnification and collapse of the lung from the pressure of insufflation are obvious. Since the operation is performed through small incisions, ranging from 3 to 5 mm, also less postoperative pain can be anticipated. Considering these potential advantages, it is not surprising that VATS procedures represent an evolving technique in the pediatric surgical community and its acceptance for various indications is widespread today.

2.4.2Ventilatory and pathophysiological considerations for VATS

In a clinical setting, SLV and VATS are well tolerated even by neonates. However, we have recently demonstrated that single-lung ventilation combined with a capnothorax of 5 mmHg in piglets caused a significantly higher decrease of cardiac index in comparison with singe-lung ventilation alone. This decrease was due to deterioration of the cardiac preload. The intrathoracic carbon dioxide insufflation led also to a significantly higher arterial carbon dioxide partial pressure caused by carbon dioxide absorption [13]. In accordance, McHoney et al. found an increased endtidal carbon dioxide concentration in children undergoing thoracoscopy which was higher than during laparoscopy [14]. Changes were more pronounced in smaller children undergoing single-lung ventilation. These changes may aggravate the belowmentioned intraoperative hypercapnia and acidosis in newborns undergoing VATS CDH-repair [15, 16]. Thus, it has to be emphasized that SLV in combination with VATS needs an experienced anesthetic team and a close intraoperative communication between anesthetist and pediatric surgeon.

2.4.3Equipment

The instrumentation for VATS is basically not different from laparoscopy. We prefer 3- to 5-mm multiuse instrumentation. To introduce the instruments and the telescope, valved ports are recommendable as compared to simple non-valved trocars to maintain the positive intrathoracic CO2 pressure which keeps the lung compressed. We use 3- to 5-mm multiuse ports and – if needed – a 12-mm single-use valved port to introduce the 11-mm endostapler. Trocar displacement remains a problem, especially in small infants. Various trocar fixation techniques have been introduced. We fix reusable unscrewed trocars to the thoracic wall using a 2 cm sleeve of a Red Robinson catheter (27 F catheter for 5-mm trocars and 24 F catheter for 3.5-mm trocars). A 2/0 suture is passed through the catheter, the skin and through the underlying fascia to inhibit dislocation (Fig. 2.4.1 and Fig. 2.4.2). The grip of the sleeve prevents trocar dislocation and allows the trocar to slide within the sleeve [17].

Fig. 2.4.1: Trocar fixation by a suture through the catheter sleeve, skin and fascia. The grip of the sleeve prevents trocar dislocation, and allows the trocar to slide within the sleeve. The trocar can easily be readjusted by pushing the sleeve toward the skin while gently pulling the trocar.

Fig. 2.4.2: Intraoperative image of trocar positioning in left lower lobectomy in a 5-year-old boy. 5-mm multiuse valved port (red valve) for introduction of the telescope below the tip of the scapula (fifth intercostal space) and three 3.5-mm multiuse valved ports (blue valves) for instrumentation. Note fascial fixation of sleeved port as described in Fig. 2.4.1.

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