The advance of medical technology has produced many significant benefits for science, medical health professionals, and patients. These advances have often improved the efficiency and efficacy of healthcare. However, new medical devices that are poorly designed or inadequately tested have also produced unwanted and dangerous consequences as well.
This is the case with medical devices designed to raise or lower the temperature of a patient, based on warming or cooling blood that is being circulated through a heart-lung machine used during cardiopulmonary bypass. Heater-cooler devices are often necessary for use during surgeries to warm or cool patients as part of their care. They are especially important tools for surgeries involving the heart and lungs (cardiothoracic surgeries). Heater-cooler devices include tanks that provide temperature-controlled water to external heat exchangers or to warming/cooling blankets through closed water circuits.
Heater-cooler devices are Class II devices that can be cleared under one of the following cardiovascular classification regulations:
870.4250 Cardiopulmonary Bypass (CPB) Temperature Controller
870.5900 Thermal Regulating System
There are a number of different heater-cooler devices approved for market use in the United States. They include the Maquet HCU 30, Sorin Stockert 3T, CardioquipMCH 1000(i), Terumo SarnsTMTCM II, and the Cincinnati Sub-Zero Hemotherm®400CE. The Sorin Stockert 3T is the most popular with the medical device enjoying 60-65% of the market. There are more than 250,000 procedures which employ this medical device in the US each year.
While the Sorin Stockert 3T is the most popular brand, medical device design experts have found significant flaws in the device including defects in the direction of airflow exhaust, a water circuit that is not airtight, original PVC tubing that promotes biofilm, an inability to access water tank & internal circuits leading to the production of biofilm, and problems with the force at which air is vented. Finally, this device has no risk analysis for contamination of the operating room or the patient.
In addition to these design defects, there have been manufacturing issues associated with the medical device. NTM (nontuberculous mycobacteria) M. Chimaera has been found at a manufacturing plant in Germany and the NTM was still present when the device was shipped to U.S.
In October 2015, the FDA issued its first communication regarding heater-cooler devices and noted that they found a connection between NTMs and the devices. Two months later, in December 2015, the FDA issued a letter to LivaNova banning imports of 3T due to violations. In June 2016, the FDA Safety Committee linked M. Chimaera to 3T heater-cooler devices and the FDA Circulatory Devices Panel determined 90% of reported device contaminations are 3T. LivaNova admitted existing devices retrofitted with new design features. In October 2016, the FDA warned hospitals that they should stop using 3T devices manufactured pre-Sept. 2014 and use caution with 3Ts manufactured post-Sept. 2014. That same month, the CDC linked the M. Chimaera in patients as genetically identical to M. Chimaera found in 3Tdevices.
According to the Centers for Disease Control, Invasive Mycobacterium chimaera infections after open-heart surgery have been reported internationally. These devastating infections result from aerosols generated by contaminated heater–cooler units used with extracorporeal circulation during surgery. Despite intensified cleaning and disinfection, surveillance samples from factory-new units acquired during 2014 grew nontuberculous mycobacteria after a median of 174 days. Mycobacterium chimaera is an emerging pathogen causing disastrous infections of heart valve prostheses, vascular grafts, and disseminated infections after open-heart surgery. Growing evidence supports airborne transmission resulting from aerosolization of M. chimaera from contaminated water tanks of heater–cooler units (HCUs) that are used with extracorporeal circulation during surgery. HCUs were previously associated with surgical site infections caused by nontuberculous mycobacteria (NTM).
The authors of the CDC study of the problem concluded, “HCUs seem to provide favorable environmental conditions for growth of NTM, in particular M. chimaera. An intensified cleaning and disinfection protocol failed to prevent growth of NTM entirely but succeeded in preventing detectable aerosolization of M. chimaera.
The contamination status of HCUs seems to be influenced by the intensity of maintenance, especially frequency of water changes. This hypothesis led to the development of the in-house maintenance protocol. The consistently negative air cultures for M. chimaera and the only intermittently positive water cultures support the benefits of our intensified protocol.
Our study design did not elucidate the origin of M. chimaera and other NTM in HCUs. The HCUs might have been already contaminated at time of delivery in a concentration below the detection threshold of mycobacterial cultures. A recent investigation confirmed the presence of environmental mycobacteria, including M. chimaera, in factory-new HCUs. In our study, 1 HCU tested positive for M. chimaera for the first time after being returned from repair at the manufacturer. Contamination from tap water is unlikely because the study HCUs used only filtered water.
Previous studies indicated the durability of mycobacteria against several disinfectants, likely because of the organisms’ complex cell wall. M. avium complex isolates were shown to have a high level of resistance against chlorine when grown in water. Corrosion, certain material characteristics, and dead-end spaces can favor biofilm formation and mycobacterial growth. Killing of NTM with heat may be promising; older studies reported a high efficacy with temperature exposure at 70°C. A recent report indicated complete suppression of M. chimaera in HCUs by intensified maintenance after a complex decontamination regimen, including replacement of plastic tubing; however, follow-up was limited to 3 months. Prolonged testing seems necessary for excluding presence of M. chimaera or other NTM.”
It is alarming that the most popular heater-cooler device, the Sorin Stockert 3T, has 15 versions of instructions for use and none of these instructions have validated cleaning & disinfection procedures.
The bacteria found in these heater-cooler devices can be lethal in post-operative patients. There are over 200 mycobacterium species which can be found in water, dust, and soil. They are generally not harmful to healthy people. Biofilm formation, which has been identified as a significant design flaw issue in these devices aids survival. Further complicating the problem, they are difficult to clean.
NTM adheres to implant materials making treatment difficult.
In 2004, a new subspecies within Mycobacterium AviumComplex was identified. It’s causing new issues for post-operative patients and specifically with problems related to the heater-cooler device. Symptom onset occurs long after the surgery is performed and is very difficult to treat with antibiotics.
The NTM bacteria are very difficult to treat in part because they are difficult to identify in a timely fashion. Symptomology can be vague including pain, unexplained fever, night sweats, muscle aches, joint pain, weight loss, fatigue, infection-site indications. Symptom onset for M. Chimaera can last up to 5-6 years post-exposure. Various clinical presentations can lead to misdiagnosis which allows the bacteria to spread throughout the body. Testing for the bacteria is a long process, taking up to more than eight weeks.
The medical issues associated with these infections can be lethal. Death has been reported in 50% of infected patients. In some cases, a second operation is required to replace the infected valve or graft and the side effects from treatment can be severe including hearing and vision loss as well as organ damage or failure.
If you or a loved one have had major heart, lung, or liver surgery within past 5 years and a heater-cooler device was used during the surgery, contact your physician immediately. You may also contact Attorney Joe Saunders for a free initial consultation.