Since the turn of the century, advancements in capability using minimally invasive surgical (MIS) techniques have been nothing short of miraculous. This article focuses on interventional procedures (involving transvascular anatomical access) within the minimally invasive surgical toolkit that includes endoscopy, laparoscopy, arthroscopy, and robot-assisted surgeries, although the primary physician is different in each case. Surgical skill sets coupled with impressive new technology and devices have enabled what were once extremely invasive procedures to now be conducted using minimal incisions, instrument/scope access (trocar or keyhole) ports, and sometimes just small diameter catheter vascular access.
The advantages that MIS brings to healthcare include reduced patient trauma and discomfort, less opportunity for infection, and faster procedural and recovery times, which usually means reduced healthcare costs. However, the need to perform highly skilled actions using specialized tools with limited visibility and ranges of motion has introduced higher levels of expertise for the surgical team, from endoscopic surgeons and robotic procedure specialists to interventional radiologists. Support equipment includes endoscopic cameras, visualization scanners, contrast injectors, nonmagnetic monitors, specialized instruments and catheters, and expensive robotic systems. Despite the setup overhead for MIS, there is no disputing the value these advances in surgical procedures bring to the industry, and today’s MIS infrastructure is pronounced and widespread in every sector of healthcare.
MIS Device Design Trends
The devices required to support MIS techniques continue to proliferate at impressive levels. Instruments have become highly specialized to do a specific task swiftly without requiring too much technique from the user such that the number of individual designs available today to surgeons is quite daunting. It is not uncommon for power users (key opinion leaders or KOLs) to develop their own version of a device based on their specific technique, which then becomes a unique offering by a partnering manufacturer. Miniaturized sensors and electronics can be integrated into the tips of these handheld instruments or within tiny catheters to monitor pressure, blood flow, and electrical fields, providing clinicians with vital anatomical feedback while working virtually blind. Combined with these sensors, some devices even provide synthesized feedback to the user, which may be in the form of haptic vibration and mechanical resistance, as well as visual and audible instructions.
Robot-assisted surgery has become a fast-moving technology that enhances the accuracy of complex surgeries while reducing patient trauma and recovery time because robots do not need direct visualization of the surgical site. Robots may be as simplistic as a smart guidance fixture for probes and cannula insertions, or as complex as a floor-standing multi-tool device that can operate remotely on patients from across the globe, controlled by skilled surgeons via advanced telemetry. Military leadership has aggressively pursued technology to enable this interoperability to vastly enhance the survivability of wounded servicemen in the field. Robots are now commonplace for orthopedic procedures such as knee and hip replacements, as well as prostate surgery where the level of precision provided by the robotic guidance far exceeds even the most skilled surgeon. Combined with 3D imaging and realtime interpolated anatomical modeling, robot-assisted surgical efficacy is driving the proliferation of targeted robotic platforms into most surgical and oncologic procedures.
MIS has its challenges — the cost of capital equipment such as imaging systems and robots can be prohibitive, and specialized training of personnel requires a team of dedicated clinicians and facilities. Cath labs have replaced many operating rooms as the value and effectiveness of interventional procedures has proven itself in the treatment of coronary disease. It is simply extraordinary to understand that today we can have our aortic valves replaced via femoral artery-accessed catheter delivery, requiring no thoracic surgical access. Tiny pumps integrated into the ends of catheters can help us pump blood from ventricle to atrium until our hearts can heal from a procedure and operate normally.
Visualization requirements associated with MIS relies on sophisticated technology to enable the clinician to see through anatomy. Without these advances, most MIS procedures would be impossible to perform with the required levels of accuracy and reliability. Camera CMOS sensors have become so small and affordable (thanks to the consumer products industry) that articulating scopes can now visualize anatomy in high-resolution video that was simply impossible just a decade ago. Features such as tissue texture and relative coloration can be assessed in real time due to HD-enhancing and color-correcting software, a performance upgrade vital to tasks such as abnormal tissue identification. Along with the physical hardware is software that can interpolate scanned anatomy to provide three-dimensional images, perhaps overlaying prescanned patient anatomy to help guide the user around tortuous pathways during device implantation.
Magnetic resonance imaging (MRI), computed tomography (CT), x-ray, ultrasound, fluoroscopy, etc. are all mature technologies, but recent advances in digital image enhancement coupled with computer processing power significantly enhance resolution for MIS applications. MRI imaging has a unique problem: any equipment in the MRI suite must be nonferrous in nature to resist the massive magnetic fields created by the scanner. Patients that require 24/7 hook-up to critical-care monitors and life-support devices such as ventilators, pumps, and monitors rely on these special MRI-compatible devices.
CT imaging requires the introduction of contrast solution into the patient’s vasculature to provide an appropriate image, with the ability to customize the consistency of the contrast solution to “match” the particular patient’s anatomy to optimize image clarity. Modern injectors provide a plethora of settings, including pre-set and custom ratios of contrast-to-saline fluid mix, pressure, and ramp profiles.
Ultrasound (U/S) imaging most recently has perhaps offered the greatest opportunity to caregivers as it is a compact (briefcase-sized), simple, safe, inexpensive technology. As a result, U/S is increasingly being paired up with a broad base of diagnostic and simple therapeutic procedures in outpatient and doctors’ office settings. An example of this is the imaging of air-infused saline for fallopian tube patency whereby the saline-based contrast medium and imaging system are far cheaper and inherently safer than other traditional methods of imaging. It is easy to extrapolate the transition of U/S imaging into home-health telemedicine (distancecare) in the future, including patient-operated fetal monitoring.
User-Centered Design in MIS Devices
Beyond the availability of cuttingedge instruments and devices, MIS specialists have to develop specific skill sets. While open-heart surgery certainly requires immense skill in its own right, performing a transcatheter aortic valve replacement entirely from a groin-area access site requires another level of training and skills. External grips at the end of long cannulae or worse, hub-located control interfaces at the proximal end of a two-meter-long, spaghettilike catheter must provide the ability to push, pull, turn, and activate features deep inside the body. Whether reviewing laparoscopic or interventional techniques, consider the lack of direct interface, low-to-zero tactile feedback coupled with compromised visualization.
It is easy to understand how important it is for these MIS devices to minimize error modalities due to poor ergonomics, repetitive stress, and nonintuitive control design. When the clinician’s eyes are the camera monitor, they should not have to refocus on the device in hand because they cannot find the actuator or adjustment feature. To assist with these challenges, some devices can be coupled to controllers that help provide feedback such as temperature, pressure and flow sensing, and high-precision deployment of miniature tools integrated within the distal tip of the embedded device to perform the procedure. These controllers can help the operator feel their way around the anatomy, providing continuous monitoring of critical parameters.
Device manufacturers are always searching for ways to de-skill the MIS process so that the average operator can likely succeed without requiring rigorous training. To this end, some designers have tried synthesizing feedback into their devices. This may involve adding electromechanically generated haptic (vibration, pulsing, resistance), audible, and visual feedback to denote various functional states during the procedure. Unfortunately, most of these devices are also single use in nature, so unit costs must also be contained, which adds to the challenges to optimize ergonomics. One strategy is to build these feedback features into a durable (reusable) part of the device so that the cost can be amortized over many cases. Miniaturization (nano) technology has also advanced to the point where the cost of medical-grade embedded sensors is becoming affordable while accurate enough to be useful.
What’s the Future for MIS Technology?
Despite the incredible growth in MIS advancements over the last two decades, these techniques are still in their adolescence, and there is much room for growth. As component performance increases and cost decreases, we can expect to see convergence of many technologies, particularly from the electronic and digital industries that will enable device manufacturers to deliver smaller, more accurate and less-expensive devices that are easier to operate for a growing range of procedures. Much in the same way that transcatheter aortic valve replacement has truly been a disruptive innovation, miniaturized robotics, nano-actuators, electronics and high-definition optics can provide even greater remote functionality at the end of a laparoscopic cannula or vascular catheter.
There has been speculation that tiny, preprogrammed robots may one day be injectable into the bloodstream or pulmonary airway where they autonomously do the job of surgeons with perhaps no trauma to the patient. Biologically engineered viruses (similar to recent mRNA COVID vaccines) may also be capable of functioning at the cellular level to obliterate cancer and other abnormalities throughout the human body. Although these scenarios may sound like they have been pilfered from the pages of scientific journals, one fact is clear — medical technology in the minimally invasive space is accelerating faster than ever in an effort to do more with less, which can only benefit across the entire healthcare continuum in the long run.
This article was written by Philip Remedios, Principal and Director of Design & Development, BlackHägen Design, Dunedin, FL. For more information, visit here .