Pectus Excavatum Vacuum Bell Not Working? These 4 Factors Determine Success or Failure

Introduction

Using the same vacuum bell, some people see a significant rise in their sternum after six months, while others notice little change after a year – where does the problem lie?

This question appears very frequently in Pectus Excavatum parent groups:

“After eight months, my child’s sternum has come up a lot.”
“We’ve stuck with it for a year, but feel almost no difference.”

Why such a large difference in outcomes with the same method? This is not a matter of individual luck, but follows identifiable patterns. Several clinical studies have systematically analysed this issue and identified key variables that affect the effectiveness of vacuum bell therapy.

1. The Principle of Vacuum Bell Therapy Determines That It Is Not Suitable for All Cases

First, understand how a vacuum bell works: it uses external negative pressure to lift the sternum and costal cartilages outward, and sustained force promotes shape changes in the cartilage.

There is a core prerequisite for this mechanism: the chest wall cartilage must have sufficient elasticity and plasticity. If the cartilage has already ossified and hardened, the pulling force of negative pressure cannot push shape changes – no matter how long you persist, noticeable improvement is unlikely.

Austrian researcher Haecker and colleagues found in long‑term follow‑up that patient age correlates significantly with treatment success – the higher the chest wall cartilage plasticity, the more pronounced the shape improvement from negative pressure correction. This finding has been confirmed in subsequent clinical reports from several European medical centres [1].

2. Key Factors Affecting Effectiveness

Factor 1: Age and Cartilage Elasticity

Age is one of the core variables affecting vacuum bell effectiveness, but it is not the only deciding factor.

In children and adolescents, the costal cartilages are in the process of ossification, have relatively good elasticity, and respond more obviously to negative pressure. With age, cartilage gradually calcifies, plasticity decreases, correction difficulty increases, and the required time lengthens.

According to the Chinese Journal of Pediatric Surgery, the window for non‑surgical correction is generally before the peak period of skeletal growth ends. Intervening during this stage tends to achieve better shape improvement [2].

Age is only a reference – cartilage status is what really matters. Two 12‑year‑olds may differ greatly: one still has good cartilage elasticity, while the other has already begun significant calcification. Therefore, suitability for vacuum bell therapy should not be judged by age alone; a specialist evaluation is needed.

Factor 2: Depression Shape and Haller Index

Not all types of Pectus Excavatum respond equally to a vacuum bell. Clinical studies show that the following conditions tend to have better outcomes:

• Symmetric depression – the sternal depression is centred and regular in shape.

• Moderate depression depth – Haller Index in the 2.5–3.5 range.

• Thin soft tissue coverage – moderate thickness of chest muscles and subcutaneous tissue for good seal.

In contrast, outcomes tend to be weaker in asymmetric pectus excavatum, severe cases with Haller Index above 3.5, and situations where the vacuum bell cannot achieve a good seal.

CT measurement of the Haller Index (transverse diameter ÷ anteroposterior diameter) is a common method for assessing depression severity. ≥ 3.25 is usually considered moderate‑to‑severe; such patients need more cautious specialist evaluation before choosing vacuum bell therapy [3].

Factor 3: Daily Wear Time and Compliance

One pattern in clinical data surprises many parents: a considerable portion of the difference in outcomes comes from wear compliance.

Haecker’s follow‑up study showed that patients who wore the device for more than 2 hours per day had significantly better shape improvement at six months than those who wore it for less than 1 hour per day [1]. Vacuum bell therapy works by gradually changing cartilage shape through sustained physical force, not through short‑term high‑intensity pressure.

• Start with 30–60 minutes per day to let the skin adapt.

• Over 2–4 weeks, gradually increase to 1.5–2 hours or more per day as tolerated.

• Wear in multiple sessions or a single session – the key is meeting the total daily time.

• Keep a log and take regular photos to track shape changes.

Factor 4: Stability of Negative Pressure

If negative pressure is too low, the lifting force is insufficient to produce effective correction. If negative pressure is too high, local skin pressure becomes excessive, leading to redness, bruising, or even skin breakdown – which then forces interruption of treatment.

Traditional vacuum bells require parents to adjust pressure manually and cannot monitor pressure changes in real time during wear. When a child moves or changes posture, the actual negative pressure may deviate from the set value, affecting correction results.

Devices with smart constant‑pressure technology (such as the EMK Yikang smart vacuum bell) use sensors to monitor negative pressure in real time and automatically adjust to maintain an appropriate range, reducing fluctuations in effectiveness and skin injury risks. The companion app allows parents to view pressure data for each session, helping them track actual usage.

Factor 5: Regular Follow‑Up

Vacuum bell therapy is not a “fit‑and‑forget” process. As the child grows and develops, the chest shape changes continuously, and the correction plan needs corresponding adjustments.

Regular follow‑ups are important for:

• Assessing correction progress

• Adjusting the negative pressure plan

• Detecting skin problems early

• Determining whether to escalate treatment strategy

A follow‑up every 3 months is generally recommended; patients with severe depression may need shorter intervals.

3. Frequently Asked Questions (FAQ)

Q1: We’ve used it for 3 months with little change. Does this mean vacuum bell therapy is not suitable for our child?

A: Three months is a preliminary evaluation point, but it is not advisable to make a final judgment based solely on this. Consider daily wear time records and the results of a specialist follow‑up. If daily wear time is less than 1 hour, the lack of noticeable improvement may relate to compliance rather than the method being unsuitable.

Q2: If the Haller Index is high, is it still worth trying a vacuum bell?

A: Patients with a high Haller Index are not entirely unsuitable for vacuum bell therapy, but a comprehensive evaluation should consider age, cartilage elasticity, depression shape, and other factors. Some moderate‑to‑severe patients can still achieve some improvement if cartilage elasticity is reasonably good. A specialist assessment is recommended.

Q3: If the cartilage has already begun to ossify, is a vacuum bell still useful?

A: Cartilage ossification is a gradual process. Patients with partial ossification may still try vacuum bell therapy, but expectations need adjustment – it may take longer and the degree of improvement may be smaller. A specialist evaluation can confirm suitability.

Q4: How can I tell if the current negative pressure is appropriate?

A: Appropriate negative pressure should give a clear upward pulling sensation on the skin, without pain or excessive purple discoloration. Mild skin redness after wearing is normal and usually fades within 30 minutes. If there is persistent pain, skin breakdown, or significant bruising, reduce the pressure or stop use and consult a professional.

Q5: Is a vacuum bell effective for adult patients with pectus excavatum?

A: In adults, cartilage elasticity is significantly lower, and vacuum bell therapy is generally less effective than in children and adolescents. However, some adult patients do see some improvement with long‑term regular wear. It may be used as an adjunct rather than a primary treatment.

4. Summary

Whether a vacuum bell is effective for pectus excavatum is not a simple “yes or no” answer. It depends on multiple factors: age and cartilage elasticity, depression shape and severity, daily wear time and compliance, pressure stability, and regularity of follow‑ups.

Understanding these variables means that if results are not satisfactory, you do not have to give up immediately – often, adjusting the wearing method or upgrading the device can make a difference. At the same time, not every case of pectus excavatum is suitable for vacuum bell therapy alone. An individualised plan based on specialist evaluation is always recommended.

References

[1] Haecker FM, Mayr J. The vacuum bell for conservative treatment of pectus excavatum: the Basle experience[J]. Pediatric Surgery International, 2003, 19(4): 317-320.

[2] Liu WY, Wang G. Advances in non‑surgical treatment of pectus excavatum[J]. Chinese Journal of Pediatric Surgery, 2015, 36(5): 390-393.

[3] Sigalet DL, Montgomery M, Harder J. Pectus excavatum: a new severity index based on computed tomography[J]. Journal of Pediatric Surgery, 2003, 38(3): 431-435.

Disclaimer: This article is for general health information only and does not constitute medical advice or a treatment plan. If you have concerns, please consult a qualified physician.

EMK Yikang Medical  focuses on the development and promotion of non‑surgical treatment solutions for chest wall deformities (pectus excavatum and Pectus Carinatum). For product information, visit our official website:  https://www.emkmed.com