SNORING IS ASSOCIATED WITH UNEXPECTED PATIENT HEAD MOVEMENT DURING MONITORED ANESTHESIA CARE VITREORETINAL SURGERY

Head-mounted surgical robots are an enabling technology for subretinal injections

Therapeutic protocols involving subretinal injection, which hold the promise of saving or restoring sight, are challenging for surgeons because they are at the limits of human motor and perceptual abilities. Excessive or insufficient indentation of the injection cannula into the retina or motion of the cannula with respect to the retina can result in retinal trauma or incorrect placement of the therapeutic product. Robotic assistance can potentially enable the surgeon to more precisely position the injection cannula and maintain its position for a prolonged period of time. However, head motion is common among patients undergoing eye surgery, complicating subretinal injections, yet it is often not considered in the evaluation of robotic assistance. No prior study has both included head motion during an evaluation of robotic assistance and demonstrated a significant improvement in the ability to perform subretinal injections compared with the manual approach. In a hybrid ex vivo and in situ study in which an enucleated eye was mounted on a human volunteer, we demonstrate that head-mounting a high-precision teleoperated surgical robot to passively reduce undesirable relative motion between the robot and the eye results in a bleb-formation success rate on moving eyes that is significantly higher than the manual success rates reported in the literature even on stationary enucleated eyes.

Anesthesia Techniques for Vitreoretinal Surgery in the United States: A Report from the Multicenter Perioperative Outcomes Group Research Consortium

PURPOSE

To explore the patterns of anesthesia use and their determinants during vitreoretinal (VR) surgeries in academic and community hospitals across the US, using data from the Multicenter Perioperative Outcomes Group (MPOG).

DESIGN

A retrospective, multicenter, cohort study.

METHODS

We queried the MPOG database of 107,066 patients undergoing VR surgeries. Patients (≥18 years) undergoing VR surgery with monitored anesthesia care (MAC) or general anesthesia (GA) from January 1, 2015 to December 31, 2021 were included. Patient-level, case-based, and institutional-level covariates were collected. We performed multivariable mixed-effects models to determine predictors of anesthesia type use. The primary outcome was the type of anesthesia (MAC or GA) used during VR surgeries. As a secondary outcome, MAC cases were further classified based on the additional use of sedation into MAC with or without sedation.

RESULTS

We found that 67.45% of VR surgery cases received MAC, and 73.63% of institutions administered MAC to more than half of cases. Random effect modeling revealed that 47.76% of the variation in MAC use was attributed to institutions. A trend toward increased use of MAC with increasing age was observed. Patients diagnosed with chronic pulmonary disease, liver disease, or a history of drug abuse were less likely to receive MAC. Conversely, we found that patients with reported alcohol abuse disorder, diabetes with complications, and those with American Society of Anesthesiologists (ASA) physical status of 4 (vs. 1, 2, or 3) were more likely to use MAC. Compared to non-complex VR surgeries, there was a notably decreased likelihood of MAC use in complex PPV (P = .004), PPV + scleral buckle (SB) for retinal detachment (P < .0001), and primary SB surgery (P < .0001).

CONCLUSIONS

Approximately 2/3 of VR anesthesia is under MAC, but GA is still preferred for SBs, complex vitrectomy, and younger patients. We show that large interinstitutional variation for using MAC in practice exists.

Eye-mounting goggles to bridge the gap between benchtop experiments and in vivo robotic eye surgery

A variety of robot-assisted surgical systems have been proposed to improve the precision of eye surgery. Evaluation of these systems has typically relied on benchtop experiments with artificial or enucleated eyes. However, this does not properly account for the types of head motion that are common among patients undergoing eye surgery, which a clinical robotic system will encounter. In vivo experiments are clinically realistic, but they are risky and thus require the robotic system to be at a sufficiently mature state of development. In this paper, we describe a low-cost device that enables an artificial or enucleated eye to be mounted to standard swim goggles worn by a human volunteer to enable more realistic evaluation of eye-surgery robots after benchtop studies and prior to in vivo studies. The mounted eye can rotate about its center, with a rotational stiffness matching that of an anesthetized patient's eye. We describe surgeon feedback and technical analyses to verify that various aspects of the design are sufficient for simulating a patient's eye during surgery.

Autonomous Needle Navigation in Retinal Microsurgery: Evaluation in ex vivo Porcine Eyes

Important challenges in retinal microsurgery include prolonged operating time, inadequate force feedback, and poor depth perception due to a constrained top-down view of the surgery. The introduction of robot-assisted technology could potentially deal with such challenges and improve the surgeon's performance. Motivated by such challenges, this work develops a strategy for autonomous needle navigation in retinal microsurgery aiming to achieve precise manipulation, reduced end-to-end surgery time, and enhanced safety. This is accomplished through real-time geometry estimation and chance-constrained Model Predictive Control (MPC) resulting in high positional accuracy while keeping scleral forces within a safe level. The robotic system is validated using both open-sky and intact (with lens and partial vitreous removal) ex vivo porcine eyes. The experimental results demonstrate that the generation of safe control trajectories is robust to small motions associated with head drift. The mean navigation time and scleral force for MPC navigation experiments are 7.208 s and 11.97 mN, which can be considered efficient and well within acceptable safe limits. The resulting mean errors along lateral directions of the retina are below 0.06 mm, which is below the typical hand tremor amplitude in retinal microsurgery.

Patients' attitudes towards the potential use of stability tape to minimize head movements during cataract surgery

INTRODUCTION

Head stabilization may reduce intra-operative risk during cataract surgery, but could be misinterpreted as "restraint." We wanted to establish patients' attitudes towards the potential use of stability-tape.

MATERIALS AND METHODS

One-hundred consecutive patients attending for local-anaesthetic cataract surgery were asked to complete a pre-operative questionnaire. This explored patient concerns and views regarding intra-operative head movement and the potential use of stability-tape.

RESULTS

All 100-patients completed the questionnaire. The median head movement concern score was 2 out of 10 (range 1-9, IQR 1-5). Eighty-four percent felt stability tape should be offered to all patients and 97% would consent for its' use. Only 6% voiced concern about the use of stability-tape (95% CI 2.2%, 12.6%).

CONCLUSION

Patients had low concern for moving their head during surgery. The concept of stability-tape to minimize head movements during cataract surgery was viewed positively by most patients. This strategy may promote safer surgery in selected cases.

Dexmedetomidine and Midazolam Sedation Reduces Unexpected Patient Movement During Dental Surgery Compared With Propofol and Midazolam Sedation

PURPOSE

Owing to its unpredictability, unexpected patient movement is one of the most important problems during surgery while under monitored anesthesia care with sedation. The purpose of this study was to compare unexpected patient movement during dental surgery while under dexmedetomidine and propofol sedation.

MATERIALS AND METHODS

The authors designed and implemented a prospective randomized controlled trial. Patients undergoing dental surgery requiring intravenous sedation were randomly assigned to dexmedetomidine and midazolam (dexmedetomidine group) or propofol and midazolam (propofol group) sedation. In each group, midazolam 0.02 mg/kg was administered in conjunction with continuous administration of dexmedetomidine or propofol to maintain a bispectral index value of 70 to 80. Unexpected patient movement interfering with the procedure was defined as acceptable, defined as no body movement or only 1 controllable movement, or unacceptable, defined as at least 2 controllable movements or any uncontrollable movement. The primary outcome was unexpected patient movement, and the secondary outcome was defined as snoring and cough reflex. Other variables included demographic and procedural characteristics. Continuous or ordinal variables were analyzed using the Student t test or Mann-Whitney test. Dichotomous or categorical variables were analyzed using the χ² test or Fisher exact test. A P value less than.05 was considered statistically significant.

RESULTS

Eighty-eight patients were enrolled in the study (dexmedetomidine group, n = 44; propofol group, n = 44). There were no relevant differences between groups for demographics and baseline variables. Intraoperative unacceptable patient movement occurred more commonly in the propofol group (n = 13; 30%) than in the dexmedetomidine group (n = 4; 9%; P = .015). Intraoperative snoring occurred more commonly in the dexmedetomidine than in the propofol group (P = .045). Incidence and number of cough reflexes were comparable between groups.

CONCLUSION

Dexmedetomidine and midazolam sedation decreases unexpected patient movement during dental surgery compared with propofol and midazolam sedation.

Intraoperative head drift and eye movement: two under addressed challenges during cataract surgery

PURPOSE

To objectively measure head drift during cataract surgery, and subjectively simulate eye movements and assess impact on surgical technique.

MATERIALS AND METHODS

Twelve consecutively recorded routine cataract operations in the Tennent Institute of Ophthalmology, Gartnavel General Hospital, Glasgow, were reviewed. The speculum was used as a fixed point and correlated with a superimposed virtual ruler to measure maximum head drift in each direction throughout the operations. To simulate intraoperative eye movement, we attached string to the cataract surgical simulator (Eyesi) eye and manually induced abduction and adduction. A calibrated scale secured to the Eyesi head ensured 5 mm eye movements were consistently created. Ophthalmology trainees performed the continuous curvilinear capsulorhexis (CCC) exercise without and with sequential eye movements. Movements were induced every three seconds. Scores were compared using a paired Student's T-test.

RESULTS

Mean head drift in the surgical recordings was 3.1 mm medially (range 2-7 mm), 2.9 mm laterally (range 2-4 mm), 2.6 mm superiorly (range 1-5 mm), and 1.9 mm inferiorly (range 1-4 mm). In 11 of 12 cases, the operating microscope had to be adjusted for head drift. Six junior trainees completed the CCC module on the Eyesi without then with eye movements. After introducing eye movements the mean Eyesi score reduced from 92.7 to 76.9 (P = 0.014), 'roundness of rhexis' score reduced from 89.4 to 57.5 (P = 0.020), and trainees operated 17 s faster (P = 0.016).

CONCLUSION

This study objectively demonstrates the under-reported clinical scenario of head drift during cataract surgery. By manipulating the Eyesi we have shown that eye movements reduce the quality of cataract surgery.

A Compact Telemanipulated Retinal-Surgery System that Uses Commercially Available Instruments with a Quick-Change Adapter

We present a telemanipulation system for retinal surgery that uses a full range of unmodified commercially available instruments. The system is compact and light enough that it could reasonably be made head-mounted to passively compensate for head movements. Two mechanisms are presented that enable the system to use commercial actuated instruments, and an instrument adapter enables quick-change of instruments during surgery. A custom stylus for a haptic interface enables intuitive and ergonomic telemanipulation of actuated instruments. Experimental results with a force-sensitive phantom eye show that telemanipulated surgery results in reduced forces on the retina compared to manual surgery, and training with the system results in improved performance.