Evaluation of AirXpanders for Breast Reconstruction: Early Experience from Sydney.

AIM: Two-staged prosthetic breast reconstruction has become a popular option involving a series of saline injections to expanders to create a pocket large enough for a permanent implant. This, however, requires frequent visits to the surgeon and numerous needle pricks with potential infection risk. A new form of tissue expander, the AirXpanders, has recently been trialed in Perth and the United States. It uses a remote-controlled release of compressed CO2 where needle punctures are avoided.
METHODOLOGY: Prospective data were collected on the first 10 patients to have the AirXpanders implant inserted for breast reconstruction at Western Sydney. The implants were inserted subpectorally as the saline expanders, and patients were instructed how to use the remote 4 weeks postoperation.
RESULTS: Ten patients (4 immediate and 6 delayed) aged between 30 and 65 (mean, 48.3 years) underwent 14 AirXpanders insertions. One patient passed away due to metastatic malignancy. With the remaining patients, the average period of active expansion was 15.8 days (r, 6-21). The average size of final implant used was 451 g (r, 195-685). The only complications were 2 seromas.
CONCLUSION: Our early results are consistent with the Perth trial. The new AirXpanders is safe to use and able to achieve satisfactory tissue expansion faster than saline expander. It also has the advantage of patient self-controlled without the need for multiple medical reviews and needle punctures.

Two-staged implant-based breast reconstruction is the commonest method of breast reconstruction.[1] Stage 1 involves saline expander insertion at subpectoral level with subsequent regular saline injections to achieve expansion. This process usually takes 3–6 months to complete.[2,3] During the expansion, patients have to go through multiple needle injections with risks of infection, psychological barrier, pain, discomfort, and sheer inconvenience. The AeroForm tissue expander (AirXpanders System; AirXpanders, Palo Alto, Calif.) was designed to circumvent these issues. Its aim was to convert the intermittent and painful boluses of saline injections in the traditional expanders to a more continuous and gentle air expansion. It is an anatomically shaped tissue expander with a tiny inner chamber reservoir of compressed carbon dioxide that can be released gradually into a preshaped nondistensible inner bag. There is an outer softer silicone shell surrounding the inner bag. The release process is controlled by a handheld remote control. The preliminary report published in 2011 showed promising results, with significant shortening of expansion time and tremendous patient satisfactory rate.[4] The AeroForm tissue expander completed the PACE (Patient Activated Controlled Expansion) trial in June 2013, and the product was subsequently approved by the Australian Therapeutic Goods Administration, which makes Australia to be the first commercial market for AirXpanders. The senior author (T.C.L.) was invited to participate in the premarket trial.

PATIENTS AND METHODS

This is a prospective study with 10 consecutive patients from Western Sydney during the period of May to November 2013.

The AirXpanders were placed in a subpectoral level same as the traditional saline expanders. Three sizes of expander implants were supplied, namely small (400 mL; width, 12.4 cm), medium (650 mL; width, 14 cm), and large (800 mL; width, 15.6 cm). The size of the expander used was based on the preoperative base width of the contralateral breast in conjunction with the intraoperative mastectomy weight. Minimal (10–20 mL) on-table inflation was administered to “pair” with a remote control. Once the pairing was established, only one remote could work with that implant. Therefore, 2 remote controls were required for a bilateral reconstruction.

Patients were instructed to start expanding from week 4 post stage 1 reconstruction. A maximum of 3 doses per day (daily maximum 30 mL) is allowed to be released by the patient. Each dose is limited to be at least 5 hours apart. The remote would automatically lock when the labeled volume was reached. Once it stopped, patients were allowed to dose once a week to compensate for air permeation until stage 2 reconstruction. Should the clinician determine additional volume was required, he/she could override and administer additional volume. Once dosing commenced in the “Clinician Fill” mode, patients would no longer be able to administer maintenance doses.

Patients were scheduled for follow-up within 1 month after the beginning of expansion. Like the traditional saline expanders, the AirXpanders patients could proceed to stage 2 reconstruction 1 month after the completion of expansion.

RESULTS

Over the 6-month period, 10 patients participated in the study with 14 AirXpanders inserted. One patient (bilateral reconstruction), unfortunately, was diagnosed with metastatic breast cancer and subsequently dropped out of the trial. Out of the remaining 12 AirXpanders (5 immediate and 7 delayed), 7 were small and 5 were medium. Average permanent implant size was 451 g (r, 195–685). The average days of active expansion was 15.8 days (r, 6–21). The average days of maintenance was 66 days (r, 26–88). Four out of 9 patients required clinician top-up at follow-up appointments where the surgeon bypassed the lock-out with an override key. The average distance to travel to visit the clinician was 177 km (r, 26–500). The only complication encountered was 2 seromas (Table 1).

Table 1.

Patient Data Chart

Most patients were very happy with the cosmetic outcomes. A representative example is shown in Figure 1.

Fig. 1.

This 48 year-old woman presented 9 years after left mastectomy for delayed breast reconstruction (A). She completed her active expansion in 11 days. Two months post stage 1 reconstruction (B, C). Her stage 2 postoperative appearance in 1 month is satisfactory (D).

DISCUSSION

The AeroForm tissue expander (AirXpanders) has unquestionably introduced a new dimension to 2-staged implant-based breast reconstruction. The advantages of needle-free, shorter expansion time and patient-controlled design have once again seen in our trial. With 30 mL/d of air inflation, the AirXpanders can reach 420 mL in 2 weeks. Hence, the average length of active expansion was merely 15 days in this group. This is significantly faster compared with the traditional saline fill expanders where our routine expansion is 60–120 mL every fortnight for 4–6 times, which in general takes about 3 months just to complete the expansion. Although the average maintenance days for the AirXpanders group was 66 days, this was largely related to both surgeons’ and patients’ availabilities for the stage 2 reconstruction. Otherwise, these patients could literally complete the breast reconstruction process within 2.5 months.

Previous radiotherapy is a relative contraindication for implant-based breast reconstruction.[5] We generally reserve implant-based reconstruction on selected patients who are not suitable for other forms of reconstruction and understand thoroughly the potential risks. There is only one patient in this group who underwent previous radiotherapy, but she did not have any complication during stage 1 reconstruction. Although the AirXpanders has been shown to be reliable with radiation,[6] it is not our protocol to give adjuvant radiotherapy during stage 1 reconstruction, and therefore, none of these AirXpanders were irradiated in our series.

The AirXpanders is particularly useful in a massive geographical location like Australia where on average this group of patients would have to drive 177 km every fortnight to visit their plastic surgeon for the traditional saline expansion. For patients taking flights, the AirXpanders manufacturer has advised patients to inform the airport security before the screening similar to any orthopedic implants or cardioverter defibrillator.[7] The patient is also given a medical card explaining the device that she has in place. In addition, like the traditional saline expanders, AirXpanders is not recommended for the use of magnetic resonance imaging as the magnetic field could potentially displace the implants.[7,8] Furthermore, the nature of CO2 being so light is another important contributing factor for patients’ comfort. When carbon dioxide is in gas form at normal atmospheric pressure, 1 L of such only weighs approximately 2 g.[9]

There are some other features which we observed but have not yet been described in the literature. During the trial, 3 sizes of AirXpanders were made available, namely small (400 mL), medium (650 mL), and large (800 mL). Both small and medium implants contain 1.3 L of CO2 in the reservoir, whereas large implant holds 2.1 L. The extra storage of CO2 in the reservoir was designed to replace and maintain the expansion in anticipation of permeation of CO2 through the AirXpanders shell. None of our patient required a large-size AirXpanders implant as all the regular commercially available breast implants are less than 800 mL. For traditional saline tissue expander, the manufacturer has a recommended fill volume but often surgeons would overexpand it to try and create a natural ptotic effect. In this study, 4 out of 9 patients required top-up of expansion at follow-up appointments. It was initially thought that this was either caused by excessive air permeation or the patients’ remote control ceased working before the “full” volume was achieved. However, we noticed that despite clinician top-up, the volume remained mostly unchanged. We later realized that this was due to 2 factors. First, the labeled volume of the AirXpanders is inclusive of the physical volume of the whole expander. It is the final total expander volume and the maximum volume of this object. For instance, a “400-mL” AirXpanders will be full when around 320 mL of CO2 is released as the implant itself constitutes around 75 mL of volume. Second, the AirXpanders contains a nondistensible inner bag that becomes rigid when the desired volume of air is released into. Hence, even when a clinician could override the lock-out, overexpansion could not be achieved as it was limited by the inner bag. All it did was simply increasing the intraluminal pressure. Because of these, it makes selecting the right size of the expander before first-stage breast reconstruction truly crucial.

It is always concerning to both patients and surgeons should the unlikely event occurs when the compressed CO2 is released totally at once. Recently, the company had to withdraw their expanders temporarily after a few instances where the valve containing the compressed air malfunctioned and the CO2 continued leaking out. However, it was reassuring to know that as the AirXpanders comprised a nondistensible inner bag, the size of the expander did not increase much beyond the allocated volume despite the intraluminal pressure rise. These patients described a feeling of the tension building up with a subsequent “pop” sensation not unlike that of a closed capsulotomy (personal communication with other surgeons participating in the trial). There was no skin issue related to the burst. One surgeon later identified a capsular tear at stage 2 reconstruction. Another surgeon immediately punctured the expander with a needle before it reached maximal pressure. No other physical harm related to this valve malfunction was reported. The company soon located the cause, which was due to stickiness of the valve from uncured sealant. They have since rectified the error.

CONCLUSIONS

In this short-term study, the AeroForm tissue expander was successfully used in patients undergoing 2-staged implant-based breast reconstruction with minimal complication. It manages to achieve satisfactory tissue expansion without the need for needle inflation. Although these preliminary data are promising and the manufacturer has expanded the range of expander implants available to breast reconstruction, a variety of sizes are needed to accommodate different requirements. It is hoped that in the near future, this tissue expander not only is used for breast reconstruction but also extends its application to other areas of plastic surgery.