Introduction

Pectus excavatum (PE) is the most common chest wall malformation and one of the most frequent major congenital anomalies, occurring in approximately one in every 300 births [1]. PE can be repaired by several approaches. The technique described by Ravitch [2] and modifications require exposure of the cartilages/sternal junctions, removal of abnormal cartilages, and fixation of the sternum in a more normal position. In 1998, a new technique of minimally invasive repair of PE (MIRPE) was first described by Nuss [3] to avoid several operative features of the modified Ravitch repair procedure. Today, the MIRPE technique is well established and represents a common used technique [4–9]. The shorter operating time, smaller incisions, and considerably less dissection have made the MIRPE procedure very appealing both to surgeons and patients, thereby resulting in a large increase of the number of patients requesting operative treatment, and consequently, an increase of the number of PE repairs. However, with the widespread use of the MIRPE procedure, the character and number of complications have increased [4, 6–8, 10–12]. Above all, recent studies report on an increasing number of near fatal complications [12–18]. Additionally, in many cases of PE, the degree of pectus deformity does not immediately warrant surgery. Some patients are reluctant to undergo surgery because of the pain associated with postoperative recovery and the risk of imperfect results. In this situation, the introduction of the vacuum bell for conservative treatment of PE has made this alternative therapy a focus of interest of patients.

The procedure of applying a vacuum to elevate the sternum was first used more than 100 years ago [19]. Despite the risks and unsatisfactory results after operative therapy for some patients, there has been little progress in the therapeutic use of the vacuum therapy during the last few decades. In the meantime, materials have improved and the vacuum devices can now exert strong forces. Our initial results using this method proved to be promising [20, 21]. Today, we report our ongoing experience using the vacuum bell for conservative treatment of PE. Note that a subset of these patients was reported previously [20, 21].

The vacuum bell

A suction cup is used to create a vacuum at the chest wall. The technique in detail is described previously [20]. Three different sizes exist allowing selection according to the individual patient’s age (Fig. 1a). The medium size model is available in a supplemental version with a reinforced silicon wall (type “bodybuilder”), e.g., for adult patients with a small deep PE. Additionally, a model fitted for young girls and women is available (Fig. 1b). Pilot studies performed by Schier and Bahr [22] showed that the device lifted the sternum and ribs immediately. We could also confirm this effect by thoracoscopy during the MIRPE procedure. We recommend using the vacuum bell for a minimum of 30 min, twice per day. The device may be used up to a maximum of several hours daily.

Fig. 1
figure 1

a Vacuum bell in three different sizes (left 16 cm, middle 19 cm, and right 26 cm in diameter). b Vacuum bell, model for adolescent girls/women

Full size image

Indication for conservative therapy with the vacuum bell includes patients who present with mild degree of PE, who want to avoid surgical procedure, and who are reluctant to undergo surgery because of pain associated with the operation. Additionally, patients’ concerns about imperfect results after surgery have to be noticed. Contraindications of the method comprise skeletal disorders, vasculopathies, coagulopathies and cardiac disorders [20]. To exclude these disorders, a standardized evaluation protocol was routinely performed before beginning the therapy. Complications and relevant side effects include subcutaneous hematoma, petechial bleeding, dorsalgia, and transient paresthesia of the upper extremities during the application.

Patients and methods

One hundred and thirty-three patients (110 males, 23 females) aged from 3 to 61 years (median 16.21 years) were treated with the vacuum bell for 1 to a maximum of 36 months. Standardized evaluation before starting the procedure included history of the patient and his family, clinical examination, cardiac evaluation with electrocardiogram, and echocardiography and photo documentation. The depth of PE was measured in a standardized supine position. Patients underwent follow-up at 3–6 months intervals including clinical examination and measurement of depth of PE.

The first application of the vacuum bell occurred under supervision of the attending doctor. The length of time of daily application of the vacuum bell varied widely between patients. Some patients followed the user instructions and applied the device twice daily for 30 min each. Patients under the age of 10 years used the device under supervision of their parents or caregivers. Some of the adult patients used the vacuum bell up to 8 h daily during office hours. Adolescent boys applied the device every night for 7–8 h. In fact, the duration and frequency of daily application depends on the patients’ individual decision and motivation.

Since 2006, in our institution, the vacuum bell was used routinely during the MIRPE procedure to elevate the sternum to allow a safer passage of the Lorenz® introducer as well as the pectus bar.

Results

During the first 1–5 applications, most of the patients experienced moderate pain in the sternum and reported a feeling of uncomfortable pressure within the chest. Adolescent and older patients developed moderate subcutaneous hematoma, which disappeared within a few hours. Temporary side effects like transient paresthesia of the upper extremities during the application and/or mild dorsalgia were reported by some patients. These symptoms disappeared when lower atmospheric pressure was used during application. Analgesic medication was not necessary in any patient. The application of the vacuum bell in children aged from 3 to 10 years was supervised by the parents. In this age group, no relevant side effects were reported.

While starting with the application, patients presented with a PE with depth from 2 to 5 cm. In 105 patients (79%), after 3 months of treatment, an elevation of more than 1 cm was documented. In 18 patients (13.5%), the sternum was lifted to a normal level after 18 months (Figs. 2 and 3). The longest follow-up after discontinuation is 5 years, and the success until today is permanent and still visible (Fig. 3). In three patients with asymmetric PE, the depth of PE has decreased after 9 months, but the asymmetry is still visible (Fig. 4). Three patients were dissatisfied with the postoperative result (2 patients after MIRPE and 1 patient after Ravitch procedure) and started treatment with the vacuum bell. Thirteen patients stopped the application after 19.9 months in average due to an unsatisfactory result (4 patients) and decreasing motivation (9 patients). Twelve patients underwent MIRPE. At follow-up, all patients were satisfied and expressed their motivation to continue the application, if necessary.

Fig. 2
figure 2

Forty-five-year-old patient, before (left: depth of PE = 2.5 cm) vacuum bell therapy and after 12 months (right: depth of PE = 0.5 cm)

Full size image
Fig. 3
figure 3

Nine-year-old boy, before (left: depth of PE = 2.8 cm) vacuum bell therapy, after 10 months (right: depth of PE = 1.6 cm) and 36 months after therapy (below)

Full size image
Fig. 4
figure 4

Ten-year-old boy with asymmetric PE, before (left) vacuum bell therapy, and after 12 months (right)

Full size image

Discussion

The vacuum method was used as early as 1910 by Lange [19]. The vacuum bell used in our patients group was developed by an engineer, who himself suffered from PE. We use this method since 2003. Long-term evidence of persistent effects of the treatment modality for more than 5 years is not yet available. However, initial results proved dramatic [20, 21], and the acceptance and compliance of patients seem to be good. Information on such new therapeutic modalities circulates not only among surgeons and pediatricians, but also rapidly among patients. In particular patients, who refused operative treatment by previously available procedures, now appear at the outpatient clinic and request to be considered for this method. From 1999 onwards, an increasing number of patients presented with PE at our department and asked to undergo the MIRPE procedure. In many cases of PE, the degree of pectus deformity does not immediately warrant surgery, yet patients may benefit from some type of nonsurgical treatment. Other patients are disinclined to undergo surgery due to possible complications after surgery, because of the pain associated with postoperative recovery and the risk of imperfect results. Thus, the introduction of the vacuum bell for conservative treatment of PE has generated much interest among patients with PE.

The success of a therapeutic procedure not only requires a good technique, but also depends on an appropriate indication. In our study patients who presented with symmetric and mild PE seemed to show a more successful outcome than those with asymmetric and deep PE. All patients except 13 were satisfied with the use of the vacuum bell, although objectively assessed improvement of PE varied among the individuals. All our patients were recommended to carry on undertaking sports and physiotherapy, so that the accompanying improvement of body control was an important factor in outcome. The participation of patients themselves in the “active” treatment of PE clearly increases motivation to maintain therapy. As demonstrated in the CT scan, the force of the vacuum bell is strong enough to deform the chest within minutes [22]. Therefore, especially in children younger than 10 years of age, the application of the vacuum bell has to be performed carefully and should be supervised by an adult.

While creating the vacuum, the elevation of the sternum is obvious and persists for a distinct period of time. Therefore, the vacuum cup may also be useful in reducing the risk of injury to the heart during the MIRPE procedure. As described previously [20, 21], we use the vacuum bell since 2006 routinely during the MIRPE procedure. In addition, the vacuum bell may be useful in a way of “pre-treatment” to surgery.

To estimate the “objective” success of this treatment modality is very difficult. The definition of success may vary considerably between individuals. Depth of PE, symmetric versus asymmetric deformity, as well as patients’ age and sex represent important variables. Various scales and measurement methods including X-rays and computed tomography have been used to quantify the degree of deformity. Our method of assessment of depth of PE is not exact enough, especially regarding the age specific differences. New methods for non-invasive assessment of chest wall growth may provide more detailed, objective information concerning the severity of PE [23]. Long-term results including 10 years and more are still missing. Further studies are necessary to elucidate these facts.

In conclusion, the vacuum bell may allow some patients with PE to avoid surgery. Especially, patients with symmetric and mild PE may benefit from this procedure. The application is easy, and we noticed a good acceptance by both pediatric and adult patients. However, the time of follow-up in our series is only 5 years, and further follow-up studies are necessary to evaluate the effectiveness of this therapeutic tool. Additionally, the intraoperative use of the vacuum bell during the MIRPE may facilitate the introduction of the pectus bar. In any case, the method seems to be a valuable adjunct therapy in the treatment of PE.