There is a compelling case for the medical community, including the device industry, to develop specific devices that are appropriate for paediatric patients. Paediatric interventional radiologists often have to “make do” and be creative in order to treat children whilst using devices that are designed for and tested on adults only. The need for appropriate devices for the paediatric population ranges from the common and simple, such as long-term feeding tubes and vascular access devices, to the expensive and biomechanically complex, such as bioabsorbable stent-grafts, say opinion leaders in the field.
There are many factors that make it difficult to tailor devices to paediatric patients (who range from neonates to teenagers) and who need devices that remain suitable and effective as the patients grow. Still, paediatric interventional radiologists see a real need for children-specific kits and are calling for incentives within the medical device industry to help drive testing and modifications for children, in order to improve patient care.
Alex Barnacle, consultant interventional radiologist, Department of Radiology, Great Ormond Street Hospital for Children, London, UK, told Interventional News: “There are almost no paediatric-specific interventional radiology devices available, other than intravenous access devices. There is a modified paediatric version of a transjugular liver biopsy set available, which is still too large for use in small children, and a paediatric transjugular intrahepatic portosystemic shunt (TIPS) set, but otherwise most devices are only available in adult sizes.”
Daniel Sze, professor, Interventional Radiology with his colleagues Matthew Lungren, assistant professor and F Glen Seidel, clinical professor from the Lucile Packard Children’s Hospital, Stanford University, Stanford, USA, said, “There are very few devices specifically tailored for children, and this is a glaring unmet need for paediatric interventional radiology. However, there has been significant movement in the interventional marketplace to optimise intravascular devices for smaller and smaller size vessels as the demand increases in the adult interventional marketplace (ie. below the knee and retrograde revascularisation procedures, radial artery access); in fact, some basic interventional tools are already maximally miniaturised (needles, wires, microcatheters). For the most part, however, adult devices continue to be the only available devices for use in children, leaving few, if any, paediatric specific device options.
Carlos J Guevara, Instructor of Radiology, Washington University School of Medicine, Mallinckrodt Institute of Radiology, St. Louis, USA, echoes their views. “Most devices are made for adult patients and therefore in many circumstances we have to get creative and use whatever tools we have available to us. I do not think there are enough adequate interventional radiology devices for use in paediatric patients and that includes common devices such as central vein catheters as well as more advanced devices such as transjugular biopsy needles and thrombolysis catheters,” he said.
Most needed devices
While there are several different types of devices that need to be tailored to provide better care for paediatric patients, some of the most apparent ones include devices for central vein access, transvenous biopsy, enteral access, fluid drainage, and endovascular procedures.
“One of the biggest challenges is finding suitable long-term feeding tubes for small children. The small calibre gastrojejunal tubes needed in young children are simply not available, and this means that small children have to either continue to have uncomfortable nasojejunal tubes for several years or we have to place large calibre 16Fr feeding devices, which are really unsuitable for children who are only a few kilograms in weight,” Barnacle pointed out.
In Guevara’s view, “Two of the most common procedures done in paediatric patients are central line placement for venous access and drain placement for abscesses. Most of the catheters are designed for adult patients and the lines or catheters have to be positioned and covered so that they are not at risk from being pulled out inadvertently by children. In some instances there is a lot of redundancy of the device outside of the body which makes it difficult for the patient, the family, and the healthcare workers who have to work with the catheters.”
Sze and colleagues also make the case for low dose (high quality) fluoroscopy. “Dose awareness has reached a peak in other modalities such as CT, but still lags somewhat in the interventional fluoroscopic suite. There are major advances on the horizon by the major manufacturers, who are close to achieving clinically advanced low-dose fluoroscopy and digital subtraction angiography without compromising image quality.
“For devices, one major area that the community hopes to see movement in is bioabsorbable medical device platforms, such as vascular stents. Other areas that need more attention include vascular access devices such as peripherally inserted central catheters (PICCs) and gastrostomy and gastrojejunal tubes. For vascular procedures, lower profile angiographic catheters of similar shapes and performance as adult models are needed,” they outlined.
Paediatric interventionalists expound that there are both inherent and external challenges to paediatric devices—for example, the biology of growing bodies is a taxing environment for permanent implantable devices. In addition, available data in adult patients may not accurately predict outcomes in children. From a technical point of view, it is their small size that can be a challenge. “The bodies of paediatric patients can be quite small and it can be challenging to adapt to carrying out a procedure in children for this reason. For example, some veins in children can be just a few millimetres wide and it can be difficult to get access. Also, since most of the equipment and devices are made for adults, this can add to the complexity of making these work when you have a small patient. For instance, when you have equipment that is designed for use in large adults (such as enteral access kits to place gastrostomy and gastrojejunostomy tubes), it is quite challenging to then use this same equipment for children,” said Guevara.
Another aspect to be considered is the type of anaesthesia needed to carry out interventional radiology procedures in children. “Most interventional radiology procedures in adults are done using moderate sedation, and that is not possible for most paediatric patients. Anaesthesia collaboration is necessary, which adds another layer of complexity,” he continued.
Barnacle agreed: “Many children are frightened when they come into hospital and can be uncooperative because of fear or because of their limited level of understanding of what is happening to them. So paediatric units have to have far more capacity for sedation and general anaesthesia cases, and this is not always easy to achieve.
Sze and colleagues point out that “With very few exceptions, paediatric patients require dedicated specialty care, not simply for the procedure alone, but for the entire care experience; this often translates into more clinic visits and family meetings, tailored patient experiences for the children with dedicated paediatric or child-life specialty ancillary or support staff, paediatric trained sedation or anaesthesia practitioners, and availability of paediatric specific subspecialty services such as intensive care units, surgery, etc.
“In terms of the procedure itself, because the cases often require general anaesthesia, communication with patients during the procedure is not possible, and depending on the age, can be difficult or impossible before and after procedures. Small body sizes render much of our existing equipment disproportionate, clumsy, or even useless. Limitations on intravascular contrast and radiation exposure can restrict or severely limit which procedures can be performed.
“Finally, the disease processes in children are generally very different from those in adults. This compounds the issues already mentioned and makes many adult interventionalists very uncomfortable treating paediatric patients, even if the interventional techniques themselves are used routinely in adults. Formal training in paediatric interventional radiology, including sub-subspecialty fellowships, is becoming more recognised and available, but is currently still quite limited,” they stated.
Improvisation can make for better care
Interventional radiology is characterised by its inventiveness and paediatric interventional radiologists are sometimes forced to apply this to their daily work in order to optimise devices for their patients.
Sze and colleagues maintain that there is often improvisation needed in paediatric interventions, mainly in intravascular procedures. “Cutting wires and catheters to length (with additional modifications on the table) is often needed, particularly in infants. Transjugular liver biopsies can be performed in infants with improvised percutaneous biopsy tools. Occasionally, cases are delayed or not feasible because of the lack of appropriately sized devices, which can sometimes be specially ordered or custom constructed, such as stent-grafts, but the FDA and local Institutional Review Boards may discourage improvisation that is perceived as risky,” they explained.
Sometimes paediatric interventionalists use miniaturised devices for other indications in order to proceed with the procedure. “Renovascular hypertension is pretty rare in children but we have a relatively large cohort of patients in our centre. We commonly use 2.5–4mm coronary artery stents to treat their renal artery stenosis, as standard stents are too large for paediatric cases,” Barnacle illustrated.
Guevara draws attention to liver biopsy patients who are at a high risk of bleeding, or ascites that require that the biopsy be obtained via a transjugular approach. “All the kits that are being manufactured are made for adults. If the patient is an infant, then these kits are too large. However in order to minimise the risk of bleeding, we sometimes have to use these large transjugular liver biopsy kits in small patients and be very careful not to injure the veins or to obtain a liver biopsy sample that traverses the liver out of the capsule,” he noted.
In May 2014, the US FDA released a guidance document stating that companies applying for premarket approval should also provide paediatric device use information. The document stated: “Section 515A requires submitters to FDA of premarket approval applications (PMAs), supplements to PMAs, humanitarian device exemptions), and product development protocols for new devices to include readily available information about paediatric subpopulations that suffer from a disease or condition that the device is intended to treat, diagnose, or cure.” The purpose of seeking this information, the US FDA said, was ultimately “to use these data to determine unmet paediatric needs in medical device development. Once unmet needs are identified, the FDA will be better able to coordinate efforts of stakeholders, device manufacturers and FDA staff to promote new device development and proper labelling of existing medical devices for paediatric use.”
“Medical technologies save lives, improve health and contribute to sustainable healthcare. Many of these products bring value to adults as well as children and newborns. In some cases, however, specific modified versions of the technology are developed to improve treatment outcomes or reduce adverse events. These range from diagnostic HIV-tests for foetuses over tracheostomy tubes for infants, to child-friendly blood-glucose meters. The medtech industry will continue to develop paediatric and child-friendly technologies in those scenarios where we can bring more value to patients in doing so,” noted MedTech Europe, an alliance of European medical technology industry associations European Diagnostic Manufacturers Association (EDMA) and Eucomed in a statement to Interventional News.
Sze and colleagues point out that the paediatric device market is very small. “Despite the fact that 25% of the US population is under 18 years of age, only about 5% of the overall healthcare expenses are applied to paediatric medical care. There is a developing consortium of interventionalists lobbying the governmental funding agencies and the device industry to invest in paediatric interventional tool development. Funding and profits are currently scant or nonexistent. We need to find a way to incentivise the development and manufacture of devices tailored for children. One possible strategy would be for the large children’s hospitals to collaborate around key needs for paediatric medical device development and research, so as to be able to reach the economies of scale needed to move the industry and the field forward.
“The FDA has been a significant barrier to new device development in general, and the small size of the paediatric market makes it nearly impossible to recoup the investments required to bring new devices to market in this space. However, this is beginning to change since the FDA has begun to address the concern of a lack of innovation in paediatrics by instituting a Pediatric Consortia Grant Program, whose goals are “to support the development of nonprofit consortia designed to stimulate projects which will promote paediatric device development.” Additionally, the FDA has removed the profit prohibition for humanitarian device exemption (HDE) devices used to treat children, which may incentivise ventures into this space,” they noted.
Barnacle concurs. “We should be taking our lead from the pharmaceutical industry, where there are often incentives for companies to extend trials into paediatric age groups. The same incentives do not seem to exist for devices, so most devices are not tested or modified for use in children,” she said.