Iatrogenic burn caused by an operating microscope: case report

Use of Microscope-Integrated Near-Infrared Fluorescence for Enhancing Deep Lymphatic Vessel Detection during Supermicrosurgical Lymphaticovenous Anastomosis: A Longitudinal Cohort Study

BACKGROUND

The default setting of microscope-integrated near-infrared fluorescence (MINIRF) using indocyanine green for locating superficial lymphatic vessels during lymphaticovenous anastomosis was limited to less than or equal to 70 percent intensity. The authors investigated whether maximizing the MINIRF intensity setting could increase the number of deep lymphatic vessels being found, thereby increasing the total number of lymphatic vessels for lymphaticovenous anastomosis.

METHODS

This longitudinal cohort study enrolled 94 patients (86 female and eight male patients) with lower limb lymphedema. Superficial lymphatic vessels were identified with the MINIRF default setting, before maximal intensity was used for deep lymphatic vessel detection. Primary/secondary endpoints included the number of superficial and deep lymphatic vessels identified. No control was used. Demographic data, intraoperative findings [including superficial and deep (indocyanine green-enhanced and non-indocyanine green-enhanced) lymphatic vessels], and severity of lymphosclerosis were recorded. Data in three regions of the lower limb (i.e., foot/above ankle, below knee, and thigh) were compared.

RESULTS

A total of 481 lymphatic vessels were identified, comprising 260 superficial and 221 deep lymphatic vessels. The median number of lymphatic vessels found per patient was five (interquartile range, four to six), and the median lymphatic vessel size was 0.63 mm (interquartile range, 0.5 to 0.8 mm). No difference was found in number (p = 0.360), size (p = 0.215), or severity of lymphosclerosis (p = 0.226) between the overall superficial and deep lymphatic vessels in the three lower limb regions.

CONCLUSIONS

Deep lymphatic vessel detection can be aided by maximizing MINIRF intensity. These deep lymphatic vessels are comparable to superficial lymphatic vessels in number, size, and functionality, making them potentially valuable for lymphedema improvement.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, II.

Resection of Intracranial Tumors with a Robotic-Assisted Digital Microscope: A Preliminary Experience with Robotic Scope

BACKGROUND

Magnified intraoperative visualization is of paramount importance during microsurgical procedures. Although the introduction of the operating microscope represented one of the most relevant innovations in modern neurosurgery, surgical vision and maneuverability can be limited in cases with unfavorable angles of attack. In such cases, the placement of the operating microscope can be difficult and result in significant discomfort to the surgeon. In previous decades, exoscopes were introduced as alternative tools to provide optimal ergonomics by decoupling the line of sight of the surgeon from the binocular lenses. However, exoscopic platforms entail interim manual adjustments of the camera position and setting. To overcome this limitation, robotic-assisted digital microscopy was developed. We have reported our preliminary experience with the RoboticScope to investigate the feasibility and safety of this novel digital system for intraoperative magnification.

METHODS

In September 2020, the RoboticScope was used to perform 3 cranial procedures for the resection of brain tumors. The surgeon's opinion was recorded to evaluate the quality of the intraoperative vision, the safety and efficacy of the surgical maneuverability, and the surgeon's personal comfort.

RESULTS

RoboticScope provided remarkable advantages in terms of enhanced workflow efficacy and increased comfort of the surgeon during the microsurgical phase of the cranial procedures. The overall quality of the intraoperative digital imaging was rated not inferior to that of traditional optical microscopes.

CONCLUSIONS

The RoboticScope is a promising device that might represent a valuable alternative to conventional tools for intraoperative visualization in the resection of intracranial tumors.

Comprehensive review of surgical microscopes: technology development and medical applications

SIGNIFICANCE

Surgical microscopes provide adjustable magnification, bright illumination, and clear visualization of the surgical field and have been increasingly used in operating rooms. State-of-the-art surgical microscopes are integrated with various imaging modalities, such as optical coherence tomography (OCT), fluorescence imaging, and augmented reality (AR) for image-guided surgery.

AIM

This comprehensive review is based on the literature of over 500 papers that cover the technology development and applications of surgical microscopy over the past century. The aim of this review is threefold: (i) providing a comprehensive technical overview of surgical microscopes, (ii) providing critical references for microscope selection and system development, and (iii) providing an overview of various medical applications.

APPROACH

More than 500 references were collected and reviewed. A timeline of important milestones during the evolution of surgical microscope is provided in this study. An in-depth technical overview of the optical system, mechanical system, illumination, visualization, and integration with advanced imaging modalities is provided. Various medical applications of surgical microscopes in neurosurgery and spine surgery, ophthalmic surgery, ear-nose-throat (ENT) surgery, endodontics, and plastic and reconstructive surgery are described.

RESULTS

Surgical microscopy has been significantly advanced in the technical aspects of high-end optics, bright and shadow-free illumination, stable and flexible mechanical design, and versatile visualization. New imaging modalities, such as hyperspectral imaging, OCT, fluorescence imaging, photoacoustic microscopy, and laser speckle contrast imaging, are being integrated with surgical microscopes. Advanced visualization and AR are being added to surgical microscopes as new features that are changing clinical practices in the operating room.

CONCLUSIONS

The combination of new imaging technologies and surgical microscopy will enable surgeons to perform challenging procedures and improve surgical outcomes. With advanced visualization and improved ergonomics, the surgical microscope has become a powerful tool in neurosurgery, spinal, ENT, ophthalmic, plastic and reconstructive surgeries.

Utility and safety of a novel surgical microscope laser light source

OBJECTIVE

Tissue injuries caused by the thermal effects of xenon light microscopes have previously been reported. Due to this, the development of a safe microscope light source became a necessity. A newly developed laser light source is evaluated regarding its effectiveness and safety as an alternative to conventional xenon light source.

METHODS

We developed and tested a new laser light source for surgical microscopes. Four experiments were conducted to compare xenon and laser lights: 1) visual luminance comparison, 2) luminous and light chromaticity measurements, 3) examination and analysis of visual fatigue, and 4) comparison of focal temperature elevation due to light source illumination using porcine muscle samples.

RESULTS

Results revealed that the laser light could be used at a lower illumination value than the xenon light (p < 0.01). There was no significant difference in visual fatigue status between the laser light and the xenon light. The laser light was superior to the xenon light regarding luminous intensity and color chromaticity. The focal temperature elevation of the muscle samples was significantly higher when irradiated with xenon light in vitro than with laser light (p < 0.01).

CONCLUSION

The newly developed laser light source is more efficient and safer than a conventional xenon light source. It lacks harmful ultraviolet waves, has a longer lifespan, a lower focal temperature than that of other light sources, a wide range of brightness and color production, and improved safety for the user's vision. Further clinical trials are necessary to validate the impact of this new light source on the patient's outcome and prognosis.

Thermal Variations of Operative Microscopes in Otology

Objectives (1) Measure temperature variations achieved by common otomicroscopes. (2) Raise awareness about possible thermal injury during otologic procedures with the advent of newer, high-powered otomicroscopes. (3) Describe optical technology that aims to reduce the potential for thermal injury. Methods A variety of otomicroscopes, with different light sources (ranging from 100W halogen to 300W xenon), were studied. Temperatures were recorded from human auricular skin with a noncontact infrared thermometer at various microscope light intensities and with use of irrigation. Multiple recordings were done at 5-minute intervals, and a working distance of 225 mm was maintained. Results Maximum skin temperatures were found to plateau relatively quickly, with higher-wattage xenon light sources reaching greater temperatures. One-way analysis of variance revealed significant differences in temperatures with decreased light intensities. High-wattage xenon light sources reached significantly higher temperatures when compared with halogen models. Discussion There is substantial variation in maximal skin temperatures reached by otomicroscopes. Temperatures can be decreased to safe levels by reducing light intensity and with use of irrigation. The maximum temperature obtained in our study was 41.4°C. Second-degree skin burns have been described with prolonged exposures to temperatures >44°C. Implications for Practice Given the described potential for burns, surgeons performing procedures on the ear and temporal bone should take precautions to diminish temperature in the operative field.

Iatrogenic surgical microscope skin burns: A systematic review of the literature and case report

Cutaneous burns associated with microscope-use are perceived to be uncommon adverse events in microsurgery. Currently, it is unknown what factors are associated with these iatrogenic events. In this report, we describe the case of a 1-year-old patient who suffered a full thickness skin burn from a surgical microscope after a L4-S1 laminectomy. Additionally, we present a systematic review of the literature that assessed the preoperative risk, outcome, and management of iatrogenic microscope skin burns. Lastly, a summary of the Food and Drug Administration's (FDA) Manufacturer and User Facility Device Experience (MAUDE) database of voluntary adverse events was reviewed and analyzed for clinical cases of microscope thermal injuries. The systematic literature review identified only seven articles related to microsurgery-related cutaneous burns. From these seven studies, 15 clinical cases of iatrogenic skin burns were extracted for analysis. The systematic review of the FDA MAUDE database revealed only 60 cases of cutaneous burns associated with surgical microscopes since 2004. Few cases of microscope burns have been described in the literature; this report is, to our knowledge, one of the first comprehensive reports of this iatrogenic event in the literature.

Using a new otologic operating microscope: unexpected complications

The present work report cases of auricular burns after routine otologic surgery possibly induced by the operating microscope. Single-center retrospective study. April 2013 to January 2014, eight children presented with auricular burns after otologic surgery. Median age was 10.1 years. Cheloid scar occurred in six cases. A small scar was present for the other two patients without any other sequelae. No patient had chondritis nor cartilage loss. There was no possibility of physical or electrical trauma in the pretragal or retroauricular cutaneous area during the operations. Therefore, the only remaining hypothesis to explain these burns was thermal damage induced by the operative microscope.

The illumination characteristics of operative microscopes

PURPOSE

Modern operative microscopes use light sources which possess the power to severely damage underlying tissue. Currently, manufacturers provide a safety warning of this possibility. However, they are unable to suggest specific settings due to a stated "lack of scientific publications on this topic". We aim to radiometrically evaluate multiple otologic microscopes at variables which effect irradiance in order to determine reference emissions levels and provide guidelines for improved intraoperative safety.

MATERIALS AND METHODS

The optical radiance of four otologic microscopes was evaluated at variable field illumination sizes (spot size), intensity settings and working distances. The spectral emission of each microscope was separately measured. The energy absorbed in skin with representative properties was then calculated as a function of time for each microscope by accounting for the emission spectrum of the microscope and the absorption spectrum of skin.

RESULTS

Microscopes showed a wide range of optical radiance based on model, spots size, intensity setting and working distances. Spectral emission of all four microscopes was centered in the visible spectrum with minimal ultraviolet or infrared contribution. A large amount of energy is absorbed by skin during usage of operative microscopes. The highest calculated absorption at 200 min of use was 736.26 J/cm(2).

CONCLUSIONS

Operative microscopes have the ability to cause patient morbidity secondary to the energy they impart. In an effort to decrease potential injury we recommend that physicians be aware of their microscopes properties and how to control variables which effect irradiance of the skin.

Auricular burns associated with operating microscope use during otologic surgery

OBJECTIVE

To raise awareness of the potential hazard of auricular burns associated with operating microscope use during otologic surgery.

STUDY DESIGN

Retrospective case series and summary of the Food and Drug Administration's (FDA) Manufacturer and User Facility Device Experience (MAUDE) database of voluntary adverse event reports pertaining to microscope related auricular thermal injuries.

PATIENTS AND SETTING

All patients who sustained auricular burns while using the operating microscope during otologic surgery at 2 tertiary academic referral centers.

MAIN OUTCOME MEASURES

Surgical procedure, microscope model, intensity of illumination, length of procedure, focal length, location and severity of burn, and patient outcome.

RESULTS

A total of 4 microscope-related auricular thermal injuries were identified from the authors' institutions. Additionally, 82 unique cases of soft tissue burns associated with the use of an operative microscope have been voluntarily reported to the FDA since 2004. A disproportionately large percent (∼ 30%) of these occurred within the field of otology, the majority of which were during tympanoplasty or tympanomastoidectomy procedures at focal length distances of 300 mm or less with xenon light source microscopes.

CONCLUSION

Simultaneous advancements in light delivery technologies and lens optics have continued to improve the efficiency of the operating microscope; however, these improvements also increase the potential for thermal injuries. Although rare, a review of the FDA MAUDE database suggests that microscope-related soft tissue burns occur more frequently in otology than any other surgical specialty. A variety of factors may help explain this finding, including the unique anatomy of the external ear with thin skin and limited underlying adipose tissue. Preventative measures should be taken to decrease the risk of thermal injuries including use of the lowest comfortable light intensity, adjusting the aperture width to match the operative field, frequent wound irrigation, and covering exposed portions of the pinna with a moist surgical sponge.